Quarterly Journal

PAN-AMERICAN JOURNAL OF AQUATIC SCIENCES - PANAMJAS Executive Editor: Maria Cristina Oddone Scientific Editors: Gonzalo Velasco, Ana Cecília Giacometti Mai, Pablo Muniz, Ronaldo Angelini, Danilo Calliari, Samantha Eslava G. Martins and Bernardo Vaz. Honorary members: Jorge P. Castello, Omar Defeo, and Kirk Winemiller. Advisory committee: Júlio N. Araújo, André S. Barreto, Sylvia Bonilla S., Francisco S. C. Buchmann, Adriana Carvalho, Marta Coll M., César S. B. Costa, Karen Diele, Ruth Durán G., Gisela M. Figueiredo, Sergio R. Floeter, Alexandre M. Garcia, Ricardo M. Geraldi, Denis Hellebrandt, David J. Hoeinghaus, Simone Libralato, Luis O. Lucifora, Paul G. Kinas, Monica G. Mai, Rodrigo S. Martins, Manuel Mendoza C., Aldo Montecinos, Walter A. Norbis, Enir G. Reis, Getúlio Rincon Fo., Marcelo B. Tesser, João P. Vieira, and Michael M. Webster. PanamJAS is a non-profit Journal supported by researchers from several scientific institutions. PanamJAS is currently indexed in Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Aquatic Sciences and Fisheries Abstracts (ASFA) Directory of Open Access Journals (DOAJ) Online Access to Research in the Environment (OARE) IndexCopernicus International Thomson BiologyBrowser database Electronic Resources from Smithsonian Institution Libraries Divulgador Científico Ensenadense Sistema de Bibliotecas SISBI-UFU PAN-AMERICAN JOURNAL OF AQUATIC SCIENCES 2006, 1-2 2009, 4 (3) Quarterly Journal ISSN 1809-9009 (On Line Version) CDU 570 Cover photo of this issue: A juvenile of Southern Elephant Seal Mirounga leonina (Mammalia, Carnivora, Phocidae). Picture taken by Renato Lopes at the Peninsula Valdez, Argentine Patagonia. Pan-American Journal of Aquatic Sciences Research articles Confirmed occurrence of the longjaw snake eel, Ophisurus serpens(Osteichthyes: Ophichthidae) in Tunisian waters (Central Mediterranean). BEN AMOR, M. M., BEN SOUISSI, J., BEN SALEM, M. & CAPAPÉ, C. ................................................251 New records of Urobatis tumbesensis (Chirichigno & McEachran, 1979) in the Tropical Eastern Pacific. MEJÍA-FALLA, P. & NAVIA, A. F. ………………………………………………………………….255 Early developmental aspects and validation of daily growth increments in otoliths of Micropogonias furnieri (Pisces, Sciaenidae) larvae reared in laboratory. ALBUQUERQUE, C. Q., MUELBERT, J. H. & SAMPAIO, L. A. N. ........................................................259 Registro da predação de girinos de rã touro (Lithobates catesbeianus) pelo biguá (Phalacrocorax brasilianus) no estuário da Laguna dos Patos, Rio Grande do Sul, Brasil. XAVIER, J. A. A. & VOLCAN, M. V. ………………………………………………………………..267 Biologia populacional de Serrapinnus notomelas (Eingenmann, 1915) (Characiformes, Cheirodontinae) em um riacho de primeira ordem na bacia do rio Dourados, Alto rio Paraná. BENITEZ, R. S. & SÚAREZ, Y. R. ………………………………………………………………….271 New records of the brachyuran crabs Hepatus pudibundus (Aethridae) and Persephona mediterranea (Leucosiidae) in their southernmost Western Atlantic distribution. MARTINEZ, G., SCARABINO, F. & DELGADO, E. A. ………………………………………………..279 Ballast water and sustainability: identification of areas for unballasting by geoprocessing — case study in Todos os Santos Bay, Brazil. TELES, L. J. S. & SAITO, C. H. ..........................................................................................................283 Distribution of planktonic cladocerans (Crustacea: Branchiopoda) of a shallow eutrophic reservoir (Paraná State, Brazil). GHIDINI, A. R., SERAFIM-JÚNIOR, M. & PERBICHE-NEVES, G. .........................................................294 First report of larval Spiroxys sp. (Nematoda, Gnathostomatidae) in three species of carnivorous fish from Três Marias Reservoir, São Francisco River, Brazil. SANTOS, M. D., ALBUQUERQUE, M. C., MONTEIRO, C. M., MARTINS, A. N., EDERLI, N. B. & BRASILSATO, M. C. ......................................................................................................................................306 The nuisance of medusae (Cnidaria, Medusozoa) to shrimp trawls in central part of southern Brazilian Bight, from the perspective of artisanal fishermen. NAGATA, R. M., HADDAD, M. A. & NOGUEIRA JR., M. ....................................................................312 Pan-American Journal of Aquatic Sciences (2009) 4 (3): 251-382 Comportamento Predatório Ex situ do Caranguejo Menippe nodifrons Stimpson, 1859 (Decapoda, Brachyura) sobre Moluscos Gastrópodes. SANTANA, G. X., FONTELES FILHO, A. A., BEZERRA, L. E. A. & MATTHEWS-CASCÓN, H. ..............326 Aspectos fitosanitarios de los manglares del Urabá Antioqueño, Caribe colombiano. SÁNCHEZ-ALFÉREZ, A. S., ÁLVAREZ-LEÓN, R., LÓPEZ, S. G. B. C. & PINZÓN-FLORIÁN, O. P. …...339 Variação sazonal e mudanças ontogênicas na dieta de Menticirrhus americanus (Linnaeus, 1758) (Teleostei, Sciaenidae) na baía de Ubatuba-Enseada, Santa Catarina, Brasil. HALUCH, C. F., FREITAS, M. O., CORRÊA, M. F. M. & ABILHOA, V. ................................................347 Do fallen fruit-dwelling chironomids in streams respond to riparian degradation? ROQUE, F. O., SIQUEIRA, T. & ESCARPINATI, S. C. ...........................................................................357 Ecotoxicological analysis of cashew nut industry effluents, specifically two of its major phenolic components, cardol and cardanol. PIMENTEL, M. F., LIMA, D. P., MARTINS, L. R., BEATRIZ, A., SANTAELLA, S. T. & LOTUFO, L. V. C. .............................................................................................................................................363 Primeiro registro de nidificação de tartarugas marinhas das espécies Eretmochelys imbricata (Linnaeus, 1766) e Lepidochelys olivacea (Eschscholtz, 1829), na região da Área de Proteção Ambiental Delta do Parnaíba, Piauí, Brasil. DE SANTANA, W. M., SILVA-LEITE, R. R., DA SILVA, K. P. & MACHADO, R. A. .............................369 Composição e abundância de ovos e larvas de peixes na baía da Babitonga, Santa Catarina, Brasil. COSTA, M. D. P. & SOUZA-CONCEIÇÃO, J. M. ..................................................................................372 Software and Book Review The Scientific GNU/Linux option. FERREIRA, C. DOS S., VAZ, B. DOS S., VELASCO, G., TAVARES, R. A., HELLEBRANDT, D. & ALBERGONE, E. H. ................................................................................................................................I Pan-American Journal of Aquatic Sciences (2009) 4 (3): 251-382 Scientific Note Confirmed occurrence of the longjaw snake eel, Ophisurus serpens (Osteichthyes: Ophichthidae) in Tunisian waters (Central Mediterranean) MOHAMED MOURAD BEN AMOR1, JAMILA BEN SOUISSI2, MOHAMED BEN SALEM1 & CHRISTIAN CAPAPÉ3 1 Unité de Recherches Zoologie et Ecologie des Milieux aquatiques, Faculté des Sciences de Tunis, Université de Tunis El Manar, Le Belvédère, 2092 Tunis, Institut National des Sciences et Technologies de la Mer, port de pêche, 2060 La Goulette, Tunisia. Email: benamor7@yahoo.fr 2 Département des Ressources Animales, Halieutiques et des Technologies Agroalimentaires, Institut National Agronomique de Tunisie, 43 avenue Charles Nicolle, cité Mahrajène, 1082 Tunis 3 Laboratoire d’Ichtyologie, case 104, Université Montpellier II, Sciences et Techniques du Languedoc, 34095 Montpellier, cedex 05, France Abstract. The record of a juvenile female Ophisurus serpens in a Tunis Southern Lagoon confirms the occurrence of the species in Tunisian waters. This record constituted the southernmost extension range of O. serpens in the Mediterranean Sea, but also the first record of the species in a perimediterranean lagoon. Key words: Description, morphometric data, meristic counts, brackish area. Resumen. Confirmación de la ocurrencia de la anguila Ophisurus serpens (Osteichthyes: Ophichthidae) en aguas de Túnez (Mediterráneo Central). El registro de una hembra juvenil de Ophisurus serpens encontrada en una laguna al sur de Tunéz confirma la ocurrencia de la especie en aguas de la Túnez, constituyendo la extensión más al sur del rango de la especie en el Mar Mediterráneo y representando el primer registro de la especie en una laguna perimediterránea. Palabras clave: descripción, datos morfométricos, conteo merístico, ambient estuarino The longjaw snake eel, Ophisurus serpens (Linnaeus 1758) is widely distributed, reported off the eastern Atlantic coast, from the Bay of Biscay (Cappetta et al. 1985) to South Africa (McCosker & Castle 1986), including Madeira (Bauchot 1986). The species is also reported elsewhere, such as in western Indian Ocean (Southern Mozambique to South Africa) and western Pacific (Japan and Australasia). Ophisurus serpens is known in western and central Mediterranean marine (Tortonese 1970; Bauchot 1986). Additionally, the species is considered as very rare in the Adriatic Sea where it lives in marine, brackish and estuarine waters between 30 and 400 m depth, on sandy and sandymuddy bottom (Dulcic et al. 2005), buried with only the head exposed, looking for preys. The longjaw snake eel was reported off the Tunisian coast by Lubet & Azzouz (1969) in the Gulf of Tunis (northern Tunisia). However, no specimen was available for confirmation according to Bradaï (2000). Additionally, the species was not reported elsewhere in Tunisian waters (Bradaï et al. 2004). Investigations regularly conducted in Tunis Southern Lagoon (Fig. 1 and 2) since 2003 allow the capture of one specimen of the longjaw snake eel. Description and the first main morphometric measurements made on a Tunisian specimen are presented in this note. Additionally, the distribution of O. serpens in both Tunisian and Mediterranean waters is commented in this paper. The specimen was collected on 24 May Pan-American Journal of Aquatic Sciences (2009), 4(3): 251-254 252 M. M. BEN AMOR ET AL. 2006 by dragnet at 2.10 m of depth (Fig. 1 and 2), on sea grass beds concomitantly with ascidians, some juvenile gilthead sea breams Sparus aurata Linnaeus, 1758, and two invasive species, both lessepsian migrants, the mollusc Fulvia fragilis (Forsskål 1775) and the crab Eucrate crenata De Haan 1835. Measurements, counts and weights were carried out on the fresh specimen. Morphometric characteristics were determined following Dulcic et al. (2005): total length (TL), preanal length (LPA), predorsal length (LPD), prepectoral length (LPP), dorsal fin length (Ld), anal fin length (La), pectoral fin length (Lp), body depth (H), head length (C), eye-diameter (O), interorbital length (Io), preorbital length (PO), number of pores in linea lateralis and length of lower jaw are summarized in Table I. The specimen was preserved in 5% buffered formalin in the Ichthyological Collection of the Faculté des Sciences of Tunis with catalogue number FSTOPHI-serpens (Fig. 3). Description, measurements and percent in total length recorded in the Tunisian O. serpens are in agreement with Tortonese (1970), Böhlke (1981), Bauchot (1986), McCosker & Castle (1986), and Dulcic et al. (2005). Regarding the maximum size of Ophisurus serpens, Bauchot (1986) reported 2.40 m for the Mediterranean specimens and McCosker & Castle (1986), 2.50 m for the south African ones as maximum total length. Jardas (1996, in Dulcic et al. 2005) noted that usual length in catch is between 500 and 1500 mm with 2400 mm maximum in the Adriatic Sea, while in the same area, Dulcic et al. (2005) reported specimens having 2000 mm, 2100 mm and 2130 mm TL, respectively. The Tunisian longjaw snake eel, 333 mm TL, was a juvenile specimen, exhibiting inconspicuous genital duct and gonads. The number of pores in linea lateralis counted in the Tunisian specimen was 149, while Dulcic et al. (2005) reported 202 pores in a specimen having 2130 mm TL. Jardas (1996, in Dulcic et al. 2005) noted 173 pores, but no information was provided about the size of the specimen. No sufficient data are available to state, if there is a relationship between number of pores in linea lateralis and total length in O. serpens; however, such hypothesis could not be totally excluded. Figure 1. Map of the Tunisian coast showing the location of Tunis Southern Lagoon (TSL). Figure 2. Map of Tunis showing the capture site of Ophisurus serpens (black star) in Tunis Southern Lagoon (TSL), Tunis Northern Lagoon (TNL), and navigation channel (NC). The snake eel has an extremely elongate and cylindrical body, anus in anterior half of the body, snout long and slender, jaws elongate and extending posteriorly beyond the eye. Dorsal, anal and pectoral fins well-developed. Teeth in one-two series in jaws, canines in front, teeth on one row on womer, enlarged anteriorly. Colour reddish-brown dorsally, belly yellowish, snout ochred, dorsal and anal find edged with grey, lateral pore brownish. The record of Ophisurus serpens in Tunis Southern Lagoon confirmed the species occurrence in Tunisian waters. Additionally, according to information recently provided by fishermen, the species was captured in the navigation channel which separates Tunis Northern Lagoon from Tunis Southern Lagoon (see Fig. 2), without mention Pan-American Journal of Aquatic Sciences (2009), 4(3): 251-254 Confirmed occurrence of the longjaw snake eel, Ophisurus serpens in Tunisian waters related to number of recorded specimens. So the species O. serpens could be considered as very rare in Tunisian waters. Similar patterns were reported from other Mediterranean areas where O. serpens was considered as a rare species (Louisy 2002). For instance, recent observations carried out off the Languedocian coast (northern Mediterranean) from Michelat et al. (2004) to date did not record the species in the area. 253 recent environmental restoration that allowed a colonization of fish species previously unknown in the area, before restoration to date (Ben Souissi et al. 2004, 2005; Mejri et al. 2004), and 62 teleost species including O. serpens were recorded in the area. This shows that the environmental restoration was successful and that the area provided sufficient resources for fishes not only to inhabit these waters, but probably to develop and reproduce. Table I. Morphometric (in mm and as % TL) data and meristic counts of the specimen of Ophisurus serpens captured in Tunis Southern Lagoon. FST-OPHI-serpens Reference %TL Morphometric characters (mm) mm Total length (TL) 333 100.0 Preanal length (LPA) 143 42.9 Predorsal length (LPD) 48 14.4 Prepectoral length (LPP) 31 9.3 Dorsal fin length (LD) 225 67.6 Anal fin length (La) 177 53.2 Pectoral fin length (Lp) 5 1.5 Body depth (H) 8 2.4 Head length (C) 42 12.6 Eye diameter (O) 2 4.8 Preorbital length (PO) 4 1.2 Interorbital length (Io) 3 0.9 Length of lower jaw 20 6 Counts Number of pores in linea lateralis 149 Pectoral fin soft rays 13 Weights (g) Total weight 11.79 Eviscerated weight 10.36 Liver weight 0.20 Off Algeria, Ophisurus serpens was formerly reported as common by Dieuzeide et al. (1954), however, although investigations were regularly conducted since 1996 to date in the area, no record was reported by Hemida (2009 pers. comm.). O. serpens is unknown off the coast of Libya (Al Hassan & El Silini 1999, Shakman & Kinzelbach 2007), off the Mediterranean coast of Egypt (El Sayed 1994) and in the eastern Levant Basin (Golani 2005). The present record constituted the southernmost extension range of O. serpens not only in the Tunisian waters, but also in the Mediterranean Sea. It was also the first record of the species in a perimediterranean lagoon (sensu Quignard & Zaouali 1980). Tunis Southern Lagoon was the focus of a Figure 3. Ophisurus serpens collected in the Tunis Southern Lagoon (FST-OPHI-serpens), scale bar = 30 mm. Acknowledgements The authors wish to thank two anonymous referees for helpful and useful comments that allowed improving the manuscript. References Al Hassan, L.A.J. & El Silini, O.A. 1999. Check-list of bony fishes collected from the Mediterranean coast of Bengazi, Libya. Revista de Biologia Marina y Oceanografía, 34(2): 291-301. Bauchot, M.L. 1986. Ophichthidae (including Echelidae). p. 577-586. In: (P.J.P. Whitehead, E. Tortonese, M.-L. Bauchot, J.-C. Hureau & J. Nielsen, Ed.), Fishes of the North-eastern Atlantic and the Mediterranean, 1984-1986, Unesco 1, Paris. Ben Souissi, J., Mejri, H., Zaouali, J., El Abed, A., Guélorget, O., Capapé, C. 2004. On the occurrence of John Dory Zeus faber Linnaeus, 1758 (Osteichthyes: Zeidae) in a perimediterranean lagoon: the Tunis Southern Lagoon (Northern Tunisia). Annales, series Historia naturalis, 14(2): 219-224. Ben Souissi, J., Mejri, H., Zaouali, J., El Abed, A., Ben Salem, M., Guélorget, O. & Capapé, C. Pan-American Journal of Aquatic Sciences (2009), 4(3): 251-254 254 2005. Teleost species recorded in Tunis Southern Lagoon after its environmental restoration (northern Tunisia, central Mediterranean). Annales, series Historia naturalis, 15(2): 157-164. Böhlke, J.E. 1981. Ophichthidae. In: W. Fischer , G. Bianchi & W. B. Scott, Ed. FAO species identification sheets for fishery purposes. Central eastern Atlantic. Fishing area 34, 47 (in part). Vol. III, Bony Fishes, Malacanthidae to Scombridae. FAO, Rome, var. pag. Bradaï, M.N. 2000. Diversité du peuplement ichtyque et contribution à la connaissance des sparidés du golfe de Gabès (Diversity of ichthyological settlement and contribution to knowledge of sparids from the Gulf of Gabès). Thesis, University of Sfax (Tunisia), 600 p. Bradaï, M.N., Quignard., J.P., Bouaïn, A., Jarboui, O., Ouannes-Ghorbel., A., Ben Abdallah., L., Zaouali, J. & Ben Salem, S. 2004. Ichtyofaune autochtone et exotique côtes tunisiennes: recensement et biogéographie (Autochtonous and exotic fish species of the Tunisian coasts: inventory and biogeography). Cybium, 28(4): 315-328. Cappetta, H., Du Buit, M. H. & Quéro, J. C. 1985. Capture de cinq espèces de poissons en dehors de leur aire de distribution connue. Cybium, 9(4): 401-403. Dieuzeide, R., Novella, M. & Roland, J. 1954. Catalgue des Poissons des côtes algériennes. Bulletin de la Station d’Aquiculture et de Pêche de Castiglione (n.s.), 4, 1952 [1953]: 1-384. Dulcic, J., Matic-Skoko, S. & Kraljejic, M. 2005. New record of serpent eel Ophisurus serpens (Linnaeus, 1758) ( Ophichthidae) in the Adriatic waters with a review of recent Adriatic records. Annales, series Historia naturalis,15(2): 181-184. M. M. BEN AMOR ET AL. El Sayed, R.S. 1994. Check-list of Egyptian Mediterranean fishes. Institute of Oceanography and Fisheries. Alexandria, Egypt: ix + 77 pp. Golani, D. 2005. Checklist of the Mediterranean Fishes of Israel. Zootaxa, 947: 1-90. Louisy, P. 2002. Guide d'identification des poissons marins. Europe et Méditerranée. Paris, Les Éditions Eugen Ulmer. 430 pp. Lubet, P. & A. Azzouz, 1969. Etude des fonds chalutables du golfe de Tunis. Bulletin de l’Institut d’Océanographie et de Pêche de Salammbô, 1(3): 87-111. McCosker, J.E & Castle, P.H.J. 1986. Ophichthidae. p. 176-186. In: M.M. Smith & P.C. Heemstra (Ed.): Smiths’ sea fishes. Springer-Verlag, Berlin, 1047 p. Mejri, H., Ben Souissi, J. Zaouali, J., El Abed, A., Guélorget, O. & Capapé, C. 2004. On the recent occurrence of elasmobranch species in a perimediterranean lagoon: the Tunis Southern Lagoon (Northern Tunisia). Annales, series Historia naturalis, 14(2): 143-158. Michelat, M., Daudet, L. & Faliph, J. 2004. La faune marine de la côte du Languedoc: approche qualitative et quantitative. Ph D dissertation, University of Montpellier II, 41 p. Quignard, J.- P. & Zaouali, J. 1980. Les lagunes périméditerranéennes. Bibliographie icthyologique annotée. Première partie: les étangs français de Canet à Thau. Bulletin de l’Office national des Pêches de Tunisie, 4(2): 293360. Shakman, E. & Kinzelbach, R. 2007. Commercial fishery and fish species composition in coastal waters of Libya. Rostocker Meereskundliche Beiträge, 18: 65-80. Tortonese, E. 1970. Osteichthyes (Pesci ossei). Parte prima. In: Fauna d’Italia. Calderini, Bologna, 564 pp. Received May 2009 Accepted July 2009 Published online July 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 251-254 Scientific Note New records of Urobatis tumbesensis (Chirichigno & McEachran, 1979) in the Tropical Eastern Pacific PAOLA A. MEJÍA-FALLA & ANDRÉS F. NAVIA Fundación colombiana para la investigación y conservación de tiburones y rayas, SQUALUS. Carrera 79 No. 6-37, Cali, Colombia. Email: pmejia@squalus.org Abstract. This report confirms the presence of Tumbes round stingray Urobatis tumbesensis in the Colombian Pacific coast, increases the species richness of the Urobatis genus in the study zone, and considerably extends the known geographic distribution range of this species in the Tropical Eastern Pacific. Key words: Batoid fishes, American rounded-rays, distribution, Colombia. Resumen. Nuevos registros de Urobatis tumbesensis (Chirichigno & McEachran, 1979) en el Pacífico Oriental Tropical. Este reporte confirma la presencia de rayas redondas americanas de Tumbes Urobatis tumbesensis en la Costa Pacífica colombiana, incrementa la riqueza de especies del género Urobatis en la zona de estudio y extiende considerablemente el rango de distribución geográfica conocido de esta especie en el Pacífico Oriental Tropical. Palabras clave: peces batoideos, rayas redondas americanas, distribución, Colombia. The Family Urotrygonidae McEachran, Dunn & Miyake 1996, that includes the American rounded- rays, is represented in the Tropical Eastern Pacific by two genera (Urobatis and Urotrygon) and by 12 species (4 and 8, respectively) (Compagno 2005). A recent study about the elasmobranch richness in Colombia (Mejía-Falla et al. 2007) confirmed the presence of the two genera and five species: Urobatis halleri (Cooper 1863), Urotrygon aspidura (Jordan & Gilbert 1882), Urotrygon chilensis (Günther 1871), Urotrygon munda Gill 1863 and Urotrygon rogersi (Jordan & Starks 1895), on the coast of the Colombian Pacific Ocean. Such study also classified the record of Urobatis tumbesensis (Chirichigno & McEachran 1979) as “in doubt”, since collected specimens or visual records had not been registered and the only records of this species were based on two bibliographic references (Estupiñán et al. 1990, Arboleda 2002). The current record is based on two specimens (one male and one female) of the family Urotrygonidae captured in artisanal shrimp trawl fishery in El Tigre, Malaga Bay, Colombian Pacific coast (Fig. 1). The male was captured on November 23rd 2006 (3º 53’42’’N, 77º 19’25’’W) and the female on June 21st 2007 (3º 52’20’’N, 77º20’10’’W). These specimens were preserved, analyzed and later donated to the Reference Ichthyological Collection of the University of Valle (CIRUV, abbreviation in Spanish), Cali, Colombia (CIRUV 006-0063 and CIRUV 007-0094, respectively). The measurements of specimens were taken following the criteria of Chirichigno & McEachran (1979) and the specific identity of specimens was validated by comparing with the description and with the proportional measurements of the holotype (Chirichigno & McEachran 1979). Both specimens presented characteristics consistent with those of the genus Urobatis and to the specific identification of Urobatis tumbesensis (Fig. 2). These individuals have nearly rounded discs, slightly wider than long; pelvic fins with abruptly rounded tips; tail stout, bearing a serrated stinging Pan-American Journal of Aquatic Sciences (2009), 4(3): 255-258 256 spine, and with a rounded caudal fin; tail length near to 85% of disc length (female 85.94% and male 85.76%); tail and top of caudal fin uniformly covered with star-shaped dermal denticle bases, enlarging towards the midline of the disc; a row of thorns with star-shaped bases along midline of disc and tail; underside smooth. Dorsal surface and caudal fin covered with a bright pattern of coarse light brown and dark wriggly lines and eye-sized spots, becoming more distinct towards the margin of the disc and on the pelvic fins; creamy ventral surface with a reticulated pattern of pale spots on a dark background around the sides and rear of the disc and pelvic fins. Moreover, the proportional measurements matched those described for the holotype (Table 1). The male total weight was 273 grams and its calcified clasper was 2.9 cm long, indicating a mature state at this size (30 cm total length). The female total weight was 872 grams and its size corresponds to the maximum ever reported in the literature (at least 41 cm total length) (Robertson & Allen 2002, 2008). Figure 1. Distribution of Urobatis tumbesensis in the Tropical Pacific Ocean. ( ) Holotype, ( ) capture sites in Ecuador, ( ) new capture site in the Colombian Pacific coast. Urobatis tumbesensis is a little known species of round ray whose description is based on three specimens, two male specimens (40.4 and 15.7 cm total length) collected from estuarine waters at P. A. MEJIA-FALLA & A. F. NAVIA depths of 1-2 meters, and a third specimen collected in 2006 near mangroves (Chirichigno & McEachran 1979, Kyne & Valenti 2007). The capture depth of these individuals is within the registered range for the species (< 20 m) (Jiménez & Bearez 1994, Robertson & Allen 2002, 2008), and the capture zones are coincident with their habitats, specifically muddy bottoms (Robertson & Allen 2002, 2008). This species was originally registered in Puerto Pizarro, Tumbes, Northern Perú (Chirichigno & McEachran 1979) and later in Salango and Santa Rosa, Ecuador (Jiménez & Bearez 1994) (Fig. 1). Robertson & Allen (2002, 2008) proposed that the distribution of this species is restricted to an area between Northern Peru and Central zone of Ecuador. However, some books of marine fishes of Ecuador have not registered such species (Massay & Massay 1999, MICIP 2006). In this way, this record of U. tumbesensis as well as confirming the presence of this species in Colombia, it also increases its distribution in approximately 600 km from the record in Ecuador (Salango) and suggests a known distribution range in the Tropical Eastern Pacific of approximately 750 km (Fig. 1). Since Kyne & Valenti (2007) suggested only one known locality for this species (Tumbes, Perú), U. tumbesensis was included in the Deficient Data category of the IUCN Red List. Thus, this paper contributes with useful information for future evaluations of threat level of this species, based on geographic distribution, which allows to calculate the extent of occurrence (B1 Criterion, UICN 2001) and/or the area of occupancy (B2 Criterion, IUCN 2001) of the species. According to the cartographic method of areas (Cartan 1978) and based on the four localities registered for the species by this study and literature, an approximate area of occupancy of 220 km2 was estimated (using quadrants of 0.5º). Additionally, it is possible that in Colombia (pers. obs.), Ecuador and Peru (P. Bearez, pers. comm.) this species presents a low abundance and fragmented distribution through the described range. In this case, there are other useful indicators for a new evaluation of the conservation status of U. tumbesensis. However, it is necessary to evaluate whether the low number of recorded individual is due to sampling problems and/or to wrong identification of the species in the area of occurrence. Moreover, U. tumbesensis is a very low proportion in the artisanal trawl fisheries’ by-catch in Colombia (Gómez & Mejía-Falla 2008). Finally, two out of four species of Urobatis of the Tropical Eastern Pacific (Urobatis concentricus and U. maculatus) are restricted to the Pan-American Journal of Aquatic Sciences (2009), 4(3): 255-258 257 New records of Urobatis tumbesensis in the Tropical Eastern Pacific northern zone, especially Mexico (southern Baja California, Gulf of California and southern Mexico). Urobatis halleri is the species with the widest distribution, while U. tumbesensis presents the narrowest one, and both species are reported in the Colombian Pacific coast. Figure 2. Urobatis tumbesensis male of 300 mm total length, captured in the Colombian Pacific coast. Table I. Proportional morphometrics of holotype (Chirichigno & McEachran, 1979) and two specimens of Urobatis tumbesensis collected in the Colombian Pacific coast. The measurements are given as percentage of total length, except TL, which is in cm. Holotype Specimen 1 Specimen 2 Morphometrics parameters (Female) (Male) (Male) Total length (cm) Disc width Preoral length Preorbital length Disc length Prenasal length Snout to maximum disc width length Orbit diameter Inter-orbital width Interspiracular length spiracle length Mouth width Internasal width 1st gill width 3th gill width 5th gill width Distance between 1st gill slits Distance between 5th gill slits Anterior margin of pelvic fin Snout- cloaca length Cloaca - sting length Cloaca - caudal origin length Cloaca - caudal fin 40.4 59.4 10.2 12.2 58.4 9.0 27.7 4.1 5.3 9.5 4.2 5.3 4.7 2.5 2.4 1.6 14.8 10.9 11.1 51.2 27.5 40.6 49.5 42.0 60.7 10.3 13.2 54.8 8.8 28.6 3.0 8.4 9.5 3.3 7.8 4.7 2.1 1.9 1.4 15.7 11.8 14.9 53.6 31.0 40.0 47.1 30.0 62.3 11.3 14.1 58.3 8.6 30.0 2.4 8.3 9.8 2.6 6.7 5,1 2.0 1.7 1,3 16,6 11.6 11,9 48.3 25.7 41.7 50.0 Pan-American Journal of Aquatic Sciences (2009), 4(3): 255-258 258 Acknowledgments The authors wish to thank the artisanal fishermen of Juanchaco, especially to E. Angulo and H. Paredes, who captured the specimens and have collaborated with studies in this area; University of Valle and E. Rubio for his logistical assistance; S. Gómez for her cooperation during the fieldwork and taking of rays measurements; L. Lewis and V. Ramírez for the English revision. This note is one of the results of the research project “Biodiversity and vulnerability of rays of the Pacific coast of Valle of Cauca: biological and ecological contributions to their conservation” of the SQUALUS Foundation, which is co-financed by the Initiative for Threatened Species (IEA, Spanish abbreviation) and PADI Foundation. References Arboleda. E. 2002. Estado actual del conocimiento y riqueza de peces, crustáceos, decápodos, moluscos, equinodermos y corales escleractineos del océano Pacífico colombiano. Tesis de Biología Marina. Universidad Jorge Tadeo Lozano, Facultad de Ciencias del Mar. Bogotá, Colombia, 189 p. Cartan. M. 1978. Inventaires et cartographies de répartition d'espéces: faune et flore. CNRS, Paris, 127 p. Chirichigno, N. & McEachran. J. D. 1979. Urolophus tumbesensis, a new stingray from the coast of Peru (Batoidea: Urolophidae). Copeia, 4: 709-713. Compagno, L. J. V. 2005. Check list of living elasmobranches. Pp. 503-548. In: Hamlett. W. C. (Ed.). Reproductive Biology and Phylogeny of Chondrichthyes: Sharks, batoids and chimaeras. Science Publishers, Enfield, 515 p. Estupiñán, F., von Prahl, H. & Rubio, E. A. 1990. Ictiofauna de la Ensenada de Utría, Pacífico colombiano. Revista de ciencias Universidad del Valle, 8: 65-75. Gómez, L. S. & P. A. Mejía-Falla. 2008. Aspectos pesqueros de los batoideos capturados artesanalmente en las localidades de Juanchaco y la Bocana, Pacífico vallecaucano. En: Payán, L. F., Muñoz-Osorio, L. A., Ramírez-Luna, V. & Mejía-Ladino, L. M. (Eds.). Memorias del I Encuentro colombiano sobre condrictios. Fundación SQUALUS, Colombia, 66 p. P. A. MEJIA-FALLA & A. F. NAVIA IUCN. 2001. Categorías y criterios de la lista roja de la UICN: versión 3.1. Comisión de Supervivencia de especies de UICN, GlandCambridge, 33 p. Jiménez, P. & Bearez, P. 2004. Peces marinos del Ecuador continental. SIMBIOE/NAZCA/ IFEA, Quito, 530 p. Kyne, P. M. & Valenti, S. V. 2007. Urobatis tumbesensis. IUCN Red List Species - World Wide Web electronic publication, accessible at http://www.iucnredlist.org. (Accessed 03/25/2008). Massay, S. & Massay, J. 1999. Peces marinos del Ecuador. Boletín Científico y Técnico del Instituto Nacional de Pesca, 12(9): 1-64. McEachran, J. D. & di Sciara, N. 1995. Peces Batiodeos. Pp.746-792. En: Fischer, W., Krupp, F., Schneider, W., Sommer, C., Carpenter, K. E. & Niem, V. H. (Eds.). Guía FAO para la identificación de especies para los fines de la pesca, Pacífico Centro Oriental. FAO, Roma, 1813 p. McEachran, J. D., Dunn, K. A. & Miyake, T. 1996. Interrelationships of the Batoid fishes (Chondrichthyes: Batoidea). Pp. 63-83. In: Stiassny, M. L., Parenty, L. & Johnson, G. D. (Eds.). Interrelationships of fishes. Academic Press, San Diego, 496 p. Mejía-Falla, P. A., Navia, A. F., Mejía-Ladino, L. M., Acero, A. & Rubio, E. 2007. Lista revisada y comentada de las especies de tiburones y rayas (Pisces: Elasmobranchii) registradas en aguas colombianas. Boletín de Investigaciones marinas y costeras, 36: 745. Ministerio de Comercio Exterior, Industrialización, Pesca y Competitividad (MICIP). 2006. Plan de Acción Nacional para conservación y manejo de tiburones de Ecuador. Ministerio de Comercio Exterior, Industrialización, Pesca y Competitividad, Quito, 44 p. Robertson, D. R. & Allen, G. 2002. Peces costeros del Pacífico Oriental Tropical: Un sistema de información. Instituto Smithsonian de investigaciones tropicales, Balboa, CD. ROM. Robertson, D. R. & Allen, G. 2008. Shore fishes of the Tropical Eastern Pacific - World Wide Web electronic publication, accessible at http://www.neotropicalfishes.org/sftep (Accessed: 30/11/2008). Received March 2009 Accepted June 2009 Published online July 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 255-258 Early developmental aspects and validation of daily growth increments in otoliths of Micropogonias furnieri (Pisces, Sciaenidae) larvae reared in laboratory CRISTIANO QUEIROZ DE ALBUQUERQUE1, JOSÉ HENRIQUE MUELBERT2 & LUIS ANDRÉ N. SAMPAIO3 1 Programa de Pós-Graduação em Oceanografia Biológica, Universidade Federal do Rio Grande. Cx. Postal 474, 96201-900- Rio Grande / RS – Brasil. e-mail: doccqa@yahoo.com.br 2 Instituto de Oceanografia, Universidade Federal do Rio Grande, Cx. Postal 474, 96201-900, Rio Grande / RS – Brasil. E-mail: docjhm@furg.br 3 Instituto de Oceanografia, Universidade Federal do Rio Grande, Cx. Postal 474, 96201-900, Rio Grande / RS – Brasil. E-mail: sampaio@mikrus.com.br Abstract. The rate of growth increment deposition in otoliths and the early development of Micropogonias furnieri larvae were studied in laboratory under salinity and temperature of 30-35 and 23-25 oC respectively. Hatching occurred between 20 to 22 h after the in vitro fecundation. Larvae presented closed mouth, unpigmented eyes and average standard length at hatch about 1.85 mm. Larvae started to feed around the 2nd day after hatch, when the eyes became fully pigmented. Laird-Gompertz growth model was applied and average, maximum and minimum instantaneous growth rate were estimated as 0.36, 0.78 and 0.14 mm.d-1, respectively. First growth increment in the otoliths was observed at the 3rd day after hatch and the increment formation rate was 1.044 per day. Average percent error in increment reading was 13.75, and lower values were observed after age 5 d. Present results support the assumption of daily growth increments in otoliths of M. furnieri larvae. Keywords: Daily growth increments, ear stones, whitemouth croaker, fish larvae. Resumo. Aspectos do desenvolvimento inicial e validação da formação de anéis diários em otólitos de larvas de corvina Micropogonias furnieri (Teleostei, Sciaenidae) cultivadas em laboratório. O desenvolvimento inicial de larvas de corvina e a taxa de formação de anéis de crescimento em otólitos foram estudados em laboratório. A eclosão das larvas ocorreu aproximadamente 22 horas após a fecundação in vitro. As larvas eclodiram com boca fechada, olhos não pigmentados e comprimento padrão em torno de 1,85 mm. A boca abriu cerca de 24 horas após a eclosão e a alimentação iniciou-se quando os olhos tornaram-se pigmentados, no segundo dia após a eclosão. O modelo de crescimento de Laird-Gompertz foi aplicado e as taxas de crescimento média e instantânea máxima e mínima foram respectivamente 0,36, 0,78 and 0,14 mm.d -1. O primeiro anel de crescimento nos otólitos surgiu em média no terceiro dia após a eclosão e a taxa de formação de anéis foi de 1,044 anel por dia. O índice de erro médio percentual na contagem de incrementos foi 13,75, com valores menores a partir do quinto dia. Os resultados encontrados permitem validar a taxa diária de formação de anéis de crescimento em larvas de M. furnieri. Palavras-chave: anéis de crescimento, otólitos, corvina, larva de peixe. Introduction Whitemouth croaker, Micropogonias furnieri (Desmarest, 1823), is one of the most important fish species in the Southern Brazilian continental shelf. Together with Cynoscion guatucupa, supports both artisanal and industrial fisheries of the Argentinean, South Brazilian and Uruguayan coastal regions (Haimovici et al. 1989; Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 260 Jaureguizar et al. 2006). M. furnieri is considered an over-fished stock since the 90s (Paiva 1997, Vasconcelos & Haimovici 2006). It is an euryhaline species distributed from Gulf of Mexico, 20o N, to the Gulf of San Matias, 41o S (Chao 1978). In Southern Brazil, spawning occurs during summer (Ibagy & Sinque 1995), mainly in coastal waters of the Patos Lagoon estuary (32º 10.18’S and 52º 7.17’W). Eggs and larvae are passively transported into the estuary, where better environmental conditions favour their development (Muelbert & Weiss 1991). To analyze the effect of these estuarine conditions on larval development it is important to understand larval growth in the field. Besides, the comprehension of changes in growth and mortality of fish may improve the understanding of environmental factors that may affect fish survival and recruitment (Cushing 1988). One of the most used techniques for studying larval growth in the environment is the analysis of daily growth increments in otoliths (Power et al. 2000, Nakaya et al. 2008). Studying the growth of fish larvae in field through otoliths requires preliminary knowledge on the rate of increment formation in the otoliths (validation), and on the existing relationship between otolith and larval growth. Validation has been approached by analysing otolith marginal increment (Moku et al. 2005), following larval cohorts (Morley et al. 2005) and by rearing larvae in laboratory, that represents one of the most used validation techniques (Campana 2001). In this study we aimed to describe the periodicity of otolith increment formation and to evaluate the first increment deposition on sagittal otoliths of M. furnieri. Additionally we intended to describe some poorly known aspects of the early development of that species like size at hatch, growth rate and first feeding. The information presented here will be important to support ongoing studies approaching M. furnieri growth in the estuary of Patos Lagoon. Materials and Methods Wild broodstock of M furnieri were captured in the vicinity of Patos Lagoon estuary (South Brazil) during December 2002, and induced to spawn in the laboratory, with gonadotrophin injections (500 UI Kg-1). Eggs were artificially fertilized, and before hatching they were transferred to small larviculture tanks (15 L). After hatching started, cultured rotifers and the algae Tetraselmis tetrathele were added daily to the tanks to maintain a final concentration of 20 and 2000 ind mL-1, respectively. Seventeen days after hatch Artemia C. Q. ALBUQUERQUE ET AL. franciscana nauplii were also offered (2 – 3 ind mL-1). Salinity was held between 25 and 30, and temperature between 23 and 25 oC during the whole experiment. Initially, after hatch 7 to 10 larvae were fixed each day using an anaesthetic solution of benzocain, and placed in alcohol 98%. After 7 days of hatching larvae were fixed at intervals between one and five days up to the 29th day. Larval standard length was measured, and saggital otoliths were removed with surgical needles. After removal, sagitta otoliths were glued on glass slides with immersion oil. All otoliths were photographed with a digital camera coupled to a light microscope (200, 400, 500 and 1000 x). Otoliths of larvae older than 10 days were mounted in epoxy glue, sanded with fine silicon carbide paper (2000, 8000 and 12000) and polished with car wax. Otoliths were measured on screen using UTHSCSA Imagetool software (University of Texas Health Science Centre at San Antonio, Texas, http://ddsdx.uthscsa.edu/dig/itdesc.html) and growth increments were counted by two independent readers on the digital images. The rate of daily increment deposition was validated by comparing the number of increments counted in the otoliths to the known age of each larva. Otoliths from 82 larvae (from 132 examined) were successful read. The number of otolith increments was plotted against real age using each reading from the individual readers as one data point in order to consider the uncertainty between readers. Precision of counting was evaluated applying the Average Percent Error (APE) (Campana 2001): APE = 100 1 R |xij − x j | ∑ R i= j x j (1) where xij is the ith age determination of the jth fish, xj is the mean age estimate of the j fish and R is the number of times that each fish was aged. A linear regression model was used to verify increment formation rate, and the slope was compared to 1 using an f test (Zar 1984). The age of formation of the first increment was determined by the frequency of occurrence of known ages with one increment and confirmed by the intercept of the linear regression between real age and growth increment number. Growth analysis was performed using linear regression and the Laird-Gompertz growth model (Ricker 1979), fitted to the length at age data using a non-linear estimation. This model is described as: Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 S l = L0 e k( 1− e − αt ) (2) Early developmental aspects and validation of growth increments in otoliths of Micropoginias furnieri larvae where Sl is standard length (mm), L0 is the length at hatch (mm), k is a dimensionless parameter, α is the exponential decay rate and t is the time (days). To obtain the instantaneous growth rate the first derivative of equation (2) was considered: G´= α.k .L0 e k( 1−e − αt )−αt (3) where G’ is the instantaneous growth rate for each day t. Results Larvae hatched with a large yolk sac, unpigmented eyes and closed mouth. Average initial standard length (L0) in vivo was 1.85 mm (±1.17 S.D.). Mouth opened twenty-four hours after hatching, however feeding initiated only 24 hours later (2 day old larvae), when the eyes became fully pigmented. The yolk sac was totally reabsorbed by 261 the 9th day, with larval standard length of about 3.5 mm. Sagittal otoliths of M. furnieri were first observed no earlier than 24 hours after larval hatch, therefore, there was not hatching checks in otoliths of M. furnieri. Otoliths extracted from the youngest larvae measured 17 µm in diameter, were flat at the inner surface (Fig. 1A) and showed one single primordiun. Initial growth increments were easily observed (Fig. 1B) and the sulcus was not formed before the 19th day, when no differences between anterior and posterior edges were noticed (Fig. 1C). After 25 days, the rostrum, which defines the anterior margin of the sagitta (Secor et al. 1991) was evident, and the surface of otoliths became rugged and opaque and the first accessory primordium was observed (Fig. 1D). Figure 1. Saggital otolith photomicrography from M. furnieri larvae reared over 24 h (A), 7 days (B), 19 days (C), 25 days (D). Bar (A, B) = 6 µm; Bar (C) = 28 µm; Bar (D) = 35 µm. Note the round shape during the initial stages (A and B) and the presence of accessory nuclei (D). On day 29 the mean standard length was 12.99 mm (±3.61 S.D.), with a minimum of 6.58 and a maximum of 17.43 mm (Table I). Two stages with reasonably different growth rates were observed (Fig. 2). Laird-Gompertz growth model parameters were estimated as α = 0.018 and k = 4.66, while L0 Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 262 C. Q. ALBUQUERQUE ET AL. was fixed at 1.85 mm (Fig.3). Instantaneous growth rate (G’) showed increasing values, with minimum, average and maximum of 0.14, 0.36 and 0.78 mm.d-1, respectively (Fig. 3). Table I. Mean standard length (SL) of larvae of M. furnieri reared in laboratory from hatching to the 29th day. S.D. = Standard deviation. Day SL (mm) S.D. Range (mm) n 0 1.85 0.17 1.98 – 1.50 7 0.75 2.54 0.12 2.67 – 2.34 6 1 2.58 0.05 2.64 – 5.50 8 2 2.51 0.26 2.84 – 2.00 7 3 2.57 0.07 2.87 – 2.55 9 4 2.67 0.10 2.84 – 2.70 4 5 2.69 0.12 2.97 – 2.70 5 7 2.84 0.05 3.86 – 3.33 6 12 4.82 0.50 5.35 – 4.10 7 14 4.51 0.37 5.21 – 3.86 11 16* 4.99 0.6 6.24 – 4.28 12 18* 5.40 0.6 6.29 – 4.41 13 20* 6.43 0.5 7.40 – 5.39 12 21* 6.91 0.75 7.81 – 4.80 8 25* 10.72 0.75 12.00 – 9.86 9 29* 12.99 3.61 17.43 – 6.58 8 * Fed with Artemia salina and rotifers SL = 0.64 Age - 5,81 R2 = 0.75 20 2 18 Standard length (mm) 16 SL = 0.18 Age + 2,17 R2 = 0.88 14 12 1 10 8 6 4 2 0 0 5 10 15 20 25 30 Age (days) Figure 2. Age (days) and standard length (mm) for M. furnieri reared in laboratory. (1) Regression line for day 0 to 16; (2) for day 16 to 29. The relationship between real age and growth increment number showed a linear pattern (Fig. 4), with slope of 1.044 (±0.008 S.E.) being significantly different from one if based on P<0.05, or not significantly different when considered at P<0.1. Analyzed otoliths showed from 0 to 29 increments that began to appear at the 1st and 2nd days, but were most often observed at the 3rd day. This result associated with the regression intercept at 1.98 days indicated that, in average, two day old larvae have otolith with zero increments and, therefore, the first increment is deposited three days after hatch. Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 Early developmental aspects and validation of growth increments in otoliths of Micropoginias furnieri larvae 2 14 1,8 Growth Model ▲- Laird-Gompertz Sl = 1.85exp(9.077(1-exp(-0.008t))) 1,6 + Instantaneous Growth Rate 10 1,4 G' (mm/day) 12 1,2 8 Sl(mm) 263 1 6 0,8 0,6 4 0,4 2 0,2 0 0 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 Time (days) Figure 3. Laird-Gompertz growth model (▲) and instantaneous growth rate (+) for all reared M. furnieri larvae during the complete experiment. 35 30 Age (days) 25 20 15 Ag e = 1.04 4R + 1.98 R 2 = 0.9 9 10 5 0 0 5 10 15 20 25 30 35 Increment number Ring numb er (R) Figure 4. Linear regression between known age (days) and increment number (R) for otoliths of M. furnieri reared in laboratory. n = 164 (82 readings x 2 readers). Average APE for all ages of M. furnieri larvae was calculated as 13.7 (Table II). The highest APE values were present at initial ages, reaching 37.0 for age 3 days. Absolute age estimates calculated from the linear model agreed better with known ages for young larvae than for older ones. The error observed for estimates at the end of the experiment (29 days) was approximately 1 day (Table II). Discussion Growth of M. furnieri larvae in captivity can be separated in two stages. Initial slow growth, when fed only with rotifera, was followed by faster growth when A. franciscana was added to the tanks. This growth feature is reported for fish larvae and related to the onset of external feeding (Zweifel & Lasker, 1976). Additionally, it is already known that larger prey promote better growth conditions than small prey (Hunter 1981). We suggest that the addition of A. franciscana, or its combination with rotifers, improved the quality of the diet and consequently larval growth. Accelerated growth rates have also been observed for sciaenidae larvae after 20 days of hatch as a result of settlement (Rooker et al., 1999) which could explain variability on growth rates in Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 264 nature. Other experiments should be conducted with the specific objective of examining what promotes that differential growth and the effect of adding larger prey to the diet of larval white-mouth croaker. Except for the first 7-8 days, otoliths of M. furnieri larvae were not easy to read. Albuquerque & Muelbert (2004) used haematoxylin to improve contrast between growth bands in M. furnieri larvae collected from an estuary. We did some tests with haematoxylin following these authors but the visualization of growth increments from the larvae held in laboratory did not improve. Nevertheless, approximately 62% of the examined otoliths were successfully read. Most of the otoliths in our study presented the first increment completed three days after hatch. The time of first increment deposition is a species-specific feature (Ekau & Blay 2000) that allows to improve the accuracy in age and growth evaluations when it is correctly estimated C. Q. ALBUQUERQUE ET AL. (Campana 2001). The time of first increment deposition can be influenced by environmental conditions like temperature and food availability (Radtke & Fey 1996) and can be influenced or coupled to some important life change, like hatch (Humphrey et al. 2005), beginning of active swimming (Laroche et al. 1982) and complete absorption of yolk sac (Peñaillo & Araya 1996). Since M. furnieri larvae started to feed around the third day after hatch, it is reasonable to suppose that the first growth increment deposition is associated to beginning of feeding, as suggested by Campana & Mosksness (1991). The variability observed on the age of first increment deposition seems to be induced by different time of first feeding. Nevertheless, for practical purposes, two days must be added to the total growth increment number on each otolith analyzed in order to estimate the real age of the larvae. Table II. Average percent error (APE) for age determination of larval M. furnieri reared in laboratory from day one to 29. The estimated age was calculated using the linear model (eq. 6) and the 95% confidence intervals (CI) are presented. Expected Estimated age n Age (days) APE increment number (days ± CI) 1 0 37.50 5 2 0 14.29 4 3 1 37.04 3.02 (±0.13) 7 4 2 26.67 4.07 (±0.13) 8 5 3 10.00 5.11 (±0.15) 7 6 4 8.16 6.16 (±0.15) 9 7 5 12.04 7.20 (±0.16) 8 12 10 2.79 12.42 (±0.20) 8 19 17 1.91 19.73 (±0.26) 7 23 21 2.57 23.91 (±0.29) 6 25 23 4.86 26.00 (±0.30) 7 29 27 7.23 30.18 (±0.33) 6 Average = 13.75 Despite the fact that the age of first increment formation is apparently species specific, our results support the assumption made by FloresCoto et al. (1998) that added two days to the total growth increment number for three sciaenid species, meaning that the time of first increment deposition is assumed to be about the third day after hatch. At a previous study Nixon & Jones (1997) added five days to the number of increments in otoliths of M. undulatus based on the conclusions presented for a co-family species (L. xanthurus). Considering the results presented here, for a co-gender species, the five days assumed by those authors could promote some underestimation on the estimated growth rates, particularly for the younger fishes. In reference to age validation, the slope of the regression should be close to one since it is expected that one growth increment is deposited each day. Our results showed a slope of 1.044 (Fig. 4) which was significantly different from 1 when at a P-level of 0.05 or not significantly different at a Plevel of 0.1 (f-test). This result highlights an important paradox based on the acceptance of a statistical result against a biological meaning. The difference from unity found at our study (0.04) has little biological importance and can only be clearly observed at advanced ages. If larger larvae and a wider age range than that used had been examined in our samples, probably the slope would be closer to unity and this difference would have not occurred. Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 Early developmental aspects and validation of growth increments in otoliths of Micropoginias furnieri larvae There is a general acceptance for daily growth increment to occur on otoliths from larvae living in favourable environmental conditions (Campana & Neilson 1985), but it was suggested that starvation could disrupt the daily formation of increments (Method & Kramer 1979). According to Siegfried & Weinstein (1989) short periods of low food availability appear not to affect increment deposition in adults or large juveniles, but may change increment formation in otoliths of larval and early juvenile fish. Additionally, Campana et al. (1987) and Jones & Brothers (1987) argued that rough environmental conditions could induce the formation of narrower growth increments hardly resolved at common microscopy. In our experiment temperature, salinity and food were controlled and we do not believe that the experimental environment presented any restriction. Therefore, we conclude that in otoliths of M. furnieri larvae, increments deposition rate is one increment per day. There are only few available studies assessing validation of daily growth increments in otoliths of Sciaenidae larvae. Our results reinforce studies developed for other Sciaenid species, as Cynoscion nebulosus (McMichael & Peters 1989), L. xanthurus (Siegfried & Weinstein 1989) and Bairdiella chrysoura (Hales & Hurley 1991) and strengthen the premise that otoliths of Sciaenid fish present daily growth increments during their entire larval stage. This is the case for most species in nature, when good otolith preparation techniques are used and good environmental conditions for growth are available. Acknowledgements The authors would like to thank Dr. Manuel Haimovici for reviewing the manuscript and the technical support received at Laboratório de Ecologia do Ictioplancton and Estação Marinha de Aquicultura. Improvements to this paper were made possible by a SACC Visiting Fellowship to C.Q.A.. C.Q.A. and J.H.M. received financial support from CNPq-Brazil. References Albuquerque, C. Q., Muelbert, J. H. 2004. The use of haematoxylin stain to improve contrast of growth increments in otoliths of larval whitemouth croaker. Journal of Fish Biology, 64: 794-798. Campana, S. E. 2001. Accuracy, precision and quality control in age determination, including a review of the use and abuse of age validation methods. Journal of Fish Biology, 59: 197-242. 265 Campana S. E. & Mosksness, E. 1991. Accuracy and precision of age and hatch date estimates from otolith microstructure examination. ICES Journal of Marine Sciences, 48: 303-316. Campana, S. E. & Neilson, D. 1985. 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Biostatistical analysis. Prenticehall. New Jersey. 718p. Zweifel, J.R. & Lasker, R. 1976 Prehatch and posthatch growth of fishes-a general model. Fishery Bulletin, 74: 609-621. Received March 2009 Accepted June 2009 Published online July 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 259-266 Scientific Note Registro da predação de girinos de rã touro (Lithobates catesbeianus) pelo biguá (Phalacrocorax brasilianus) no estuário da Laguna dos Patos, Rio Grande do Sul, Brasil JOÃO ANTÔNIO AMARAL XAVIER1 & MATHEUS V. VOLCAN 2 1 Pós-Graduação em Aquicultura, Laboratório de Aquacultura Continental (LAC/FURG). BR 392, Km 22, vila da Quinta, Rio Grande-RS, Brasil. Email: joaoax@gmail.com 2 Instituto Pró-Pampa (IPPampa), Laboratório de Ictiologia. Gomes Carneiro, 1043. Bairro Centro, Pelotas-RS, Brasil. Email: matheusvolcan@hotmail.com Abstract: Record of predation of tadpoles of bullfrog (Lithobates catesbeianus) by biguá (Phalacrocorax brasilianus) in the estuary of the Patos Lagoon, Rio Grande do Sul, Brazil. We report here the predation of tadpoles of the bullfrog (Lithobates catesbeianus) by biguá in the estuary of the Patos Lagoon. Keywords: exotic species, environmental impact, Lithobates catesbeianus, Phalacrocorax brasilianus. Resumo: Registramos aqui a predação de girinos da rã touro (Lithobates catesbeianus) pelo biguá (Phalacrocorax brasilianus) no estuário da Laguna dos Patos. Palavras-chave: espécie exótica, impacto ambiental, Lithobates catesbeianus, Phalacrocorax brasilianus. A invasão de espécies exóticas pode afetar seriamente a biodiversidade de um determinado local, causando impactos ecológicos por competição, predação, propagação de doenças e até hibridizações, sendo considerada uma das maiores causas da perda de diversidade e extinção em escala global (Wilson 1988; Mack et al. 2000). A rã touro Lithobates castebeianus (Shaw 1802) é um anfíbio da ordem Anura da família Ranidae, cuja distribuição original ocorre no sul do Canadá, sul e leste dos Estados Unidos até o golfo do México (Hecnar & M’Closkey 1997, Ficetola et al. 2007), mas no último século foi introduzida em mais de 40 países em quatro continentes em virtude da sua utilização no controle biológico, na aquacultura e ornamentação (Jennings & Hayes 1985, Lever 2003, Barraso et al. 2009). No Brasil a L. catesbeianus ocorre principalmente em áreas de Mata Atlântica, mas existem registros de sua introdução desde a região Nordeste até o Uruguai, área considerada altamente suscetível à introdução desta espécie em virtude das características climáticas e hidrológicas (Ficetola et al. 2007, Giovanelli et al. 2008, Laufer et al. 2008, Instituto Hórus 2009). A introdução da rã touro é considerada uma das maiores responsáveis pelo declínio global das populações de anfíbios (Fisher & Shafer 1996, Alford & Richards 1999, Blaustein & Kiesecker 2002) e de várias outras espécies de vertebrados e invertebrados (Kats & Ferrer 2003, Wylie et al. 2003, Boelter 2004, Hirai 2004, Bühler & Barros 2007), entretanto, são poucos estudos que destaquem potenciais predadores desta espécie (Smith et al. 1999). O biguá Phalacrocorax brasilianus (Gmelin 1789) é uma ave de hábitos aquáticos, sendo encontrada da Tierra del Fuego, Patagônia, Pan-American Journal of Aquatic Sciences (2009), 4(3): 267-270 268 Argentina até a costa do Texas, E.U.A. (Del Hoyo et al. 1992). Alimenta-se principalmente de peixes, entretanto, ocorrem alterações temporárias na dieta em termos de itens alimentares, abundância e tamanho de presas, revelando uma elevada plasticidade alimentar (Silva 2006, Barquete et al. 2008). No dia 22 de outubro de 2008, três girinos de rã touro (Fig. 1) foram regurgitados por um exemplar de biguá em um trapiche localizado às margens do estuário do Saco do Justino, Laguna dos Patos, município de Rio Grande, Rio Grande do Sul, Brasil (32º01'40" S 52º05'40" W) (Fig. 2 e 3). Os girinos foram coletados logo após o bando, constituído apenas por biguás, abandonar o local. Os exemplares foram fotografados, fixados em formalina 10% e posteriormente transferidos para álcool 70%. Figura 1. Regurgito do biguá (Phalacrocorax brasilianus) contendo três girinos de rã touro (Lithobates catesbeianus) encontrado no trapiche do Saco do Justino, estuário da Laguna dos Patos. No entorno do estuário na Laguna dos Patos existem diversos cultivos de peixes, principalmente policultivo de carpas. Os peixes que povoam esses tanques são oriundos de diversos locais do Estado (principalmente da região Central e Norte), onde já há registro da introdução de rã touro nos ecossistemas naturais (Boelter 2004, Ficetola et al. 2007, Instituto Hórus 2009). Nesta região, muitos tanques de cultivo onde são produzidos alevinos também são habitados pela rã touro, que se reproduzem nestes locais. Muitas vezes ao comprar alevinos destas regiões, involuntariamente são capturados, juntamente com os alevinos, girinos de rã touro, que são transportados e conseqüentemente liberados junto com estes nos tanques de cultivo, sem que se realize uma triagem antes da soltura (Graeff et al. 2001). Além disso, o incorreto manejo realizado em ranários possivelmente esteja contribuindo para a introdução e propagação da rã J. A. A. XAVIER & M. V. VOLCAN touro na região. Figura 2. Localização da área do estuário do Saco do Justino, onde foi registrado o regurgito contendo os três girinos de Lithobates catesbeianus na Laguna dos Patos, município de Rio Grande, Rio Grande do Sul, Brasil. Autor: H. P. B. Neto. Fonte: Modificado de IBGE 2003 e Fepam 2005. Barquete et al. (2008), em estudo realizado na desembocadura do estuário da Laguna dos Patos, fizeram a análise de 287 regurgitos de P. brasilianus e 97% deles eram constituídos por peixes, não tendo encontrado girinos entre os itens alimentares da ave. Entretanto, pela proximidade de tanques de cultivos e pequenos banhados (ambientes que por serem lênticos proporcionam ótimo local para reprodução e criação da rã touro) ao estuário do Saco do Justino, é comum encontrar biguás forrageando nesses locais. Possivelmente o biguá alimentou-se em uma área úmida adjacente ao estuário e buscou repouso junto ao bando no trapiche (Fig. 3), onde foi encontrado o regurgito. Figura 3. Trapiche onde foi encontrado o regurgito, com bando de biguás pousados, localizado no Saco do Justino, estuário da Laguna dos Patos, município de Rio Grande. Pan-American Journal of Aquatic Sciences (2009), 4(3): 267-270 Registro da predação p de giirinos de rã toouro pelo biguuá no estuário da Laguna doos Patos, RS Atuualmente exeemplares aduultos da rã touro t já são encoontrados no entorno do estuário e do Saco do Justino, assim como girinos (J. A. A A. Xavier com. pess.), o quue evidencia a introduçãoo e a reproddução da espécie nos ecossisttemas da reggião. O reguurgito do biguá coontendo os trrês girinos dee L. catesbeiianus representa o primeiro registro da espécie paara o município de Rio Grande G e o seu pontoo de ocorrência mais m austral no Brasil. Agradecim mentos Som mos gratos ao Alexanddro Tozetti pela identificaçãão do materiial, à Alincaa Fonseca, Mario M Figueiredo e Luis Estebban Lanés pelas p sugestõões e revisão do texto, t aos trêês revisores não n identificcados pelas sugestões refereentes ao manuscrito, m e ao m da áreea de Hélio Bretttas pela connfecção do mapa estudo. Referências Bibliográfficas Alford, R. A. & Ricchards, S. J. J 1999. Global amphhibian declinnes: a probblem in appplied ecoloogy. Annual Review of o Ecology and Systeematics, 30: 133–165. Barquete, V., V Bugoni, L. & Vooreen, C. M. 2008. 2 Diet of neotropicc cormorantt (Phalacroccorax ment. brasiilianus) in an estuarinne environm Mariine Biology, 153: 431–4443. Barrasso, D. D A., Cajadee, R., Nendaa, S. J., Balooriani G. & Herrera R. R 2009. Intrroduction off the Amerrican Bullfrrog Lithobattes catesbeiianus (Anuura: Ranidaee) in Naturaal and Moddified Envirronments: An A Increasinng Conservation Probllem in Arrgentina. 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Changes inn the composition of a ranid frog communityy following bull-frog extinction. American n Midland Naturalist, 137: 145-150 0. Hiraai T. 2004. Diet com mposition off introducedd bullfrog, Rana ccatesbeiana, in thee Mizorogaiike Pond of Kyo oto, Japan.. Ecologicaal Research, 19: 375-380 0. Instiituto Hórus (2009) Base de dados de espéciess invasorras exóticas no Brasil.. http://ww ww.institutoh horus.org.brr/. Citadoo em 23 Junnho de 2009. Jenn nings, M. R. R & Hayes, M. P. 1985. Pre-19000 overharveest of Califfornia red-leegged frogss (Rana aurrora draytonnii): the ind ducement forr bullfrog (Rana cateesbeiana) introduction. i . Herpetoloogica, 41: 944–103. Katss L. B. & Feerrer R. P. 20003. Alien predators andd amphibiann declines: reeview of two o decades off science and a the trannsition to conservation. c . Diversity and Distrib butions. 9: 99 9-110. Leveer, C. 2003. Naturalized amph hibians and d reptiles of o the worrld. Oxford d Universityy Press, New w York, 280 p. Lauffer G., Canaavero A., N Nunes D. & Maneyro R.. 2008. Buullfrog (Lithobates ca atesbeianus)) invasion in Uruguay. Biologicall Invasions,, 10: 1183––1189. Macck, R. N.; Simberloff, D.; Lonsdaale, W. M.;; Evans, H..; Clout, M. N. & Bazzaazz, F. 2000.. Biotic invvasions: causes, epidemio ology, globall consequennces and conntrol. Issues in Ecology,, 5: 1-20. Silva, R. R. V. 2006. 2 Estruttura de uma comunidadee de aves em m Caxias do Sul, Rio Graande do Sul,, Brasil. Biociências, P Porto Alegre,, 14 (1): 27-- Pan-Americcan Journal off Aquatic Scieences (2009), 4(3): 4 267-2700 270 36. Smith, G. R., Rettig, J. E. & Mittelbach, G. G. 1999. The effects of fish on assemblages of amphibians in ponds: a field experiment. Freshwater Biology, 41: 829–837. Wilson, E. O. 1988. The current state of biological diversity. Pp 3-18. In: E. O. Wilson (Ed.), J. A. A. XAVIER & M. V. VOLCAN Biodiversity. Washington, DC: National Academic Press. 538 p. Wylie G., Casazza L. M. & Carpenter M. 2003. Diet of bullfrog in relation to predation on giant garter sanques at Colusa National Wildlife Refuge. California Fish and Game, 89: 139145. Received May 2009 Accepted June 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 267-270 Biologia populacional de Serrapinnus notomelas (Eingenmann, 1915) (Characiformes, Cheirodontinae) em um riacho de primeira ordem na bacia do rio Dourados, Alto rio Paraná ROSANGELA S. BENITEZ & YZEL R. SÚAREZ Universidade Estadual de Mato Grosso do Sul/Centro Integrado de Análise e Monitoramento Ambiental/Laboratório de Ecologia. Rod. Dourados-Itahum km 12. CEP 79804-970. Dourados-MS, Brazil. e-mail: yzel@uems.br Abstract: Population biology of Serrapinnus notomelas (Characiformes Cheirodontinae) in a first order stream of the Dourados river, Upper Paraná River. In the present study we analyzed the length/weight relationship, growth parameters, mortality, recruitment and we evaluated the influence of the seasonal variation on the individuals weight and recruitment pattern in the Chico Viégas stream, Mato Grosso do Sul. The samplings were accomplished monthly from october/2006 to september/2007, with a rectangular sieve of metallic frame (1.2 x 0.8 m) with 2 mm mesh size, in a portion of approximately 200 meters. We collected 464 individuals, varying from 12 to 34 mm of standard length. The equation that describes the length/weight relationship is: Total Weight=0.00000077*Standard Lenght 3.83. The asymptotic length estimated to S. notomelas was of 35.8 mm and the condition factor presented larger values in the spring and summer and the recruitment varying seasonally, with larger values in the autumn and winter. The growth rate for S. notomelas was elevated (k=1.05), also the natural mortality (Z=1.61), while the longevity was low (2.85 years). We observed that the species presented positive alometric growth, with seasonal influence in the recruitment, and condition factor. Key-Words: Populational ecology, Fishes, Growth parameters, Seasonality, Recruitment, Mortality. Resumo: No presente trabalho analisamos a relação peso/comprimento, parâmetros de crescimento, mortalidade, recrutamento e avaliamos a influência da variação sazonal sobre o peso dos indivíduos e padrão de recrutamento no córrego Chico Viegas, Mato Grosso do Sul. As amostragens foram realizadas mensalmente de outubro/2006 a setembro/2007, com uma peneira retangular de armação metálica (1,2 x 0,8 m) confeccionada com tela mosquiteiro (2 mm de abertura de malha), em um trecho de aproximadamente 200 metros. Coletamos 464 indivíduos, variando entre 12 e 34 mm de comprimento padrão. A equação que descreve a relação peso total/comprimento padrão é: Peso=0,00000077*Comprimento Padrão3,83. O comprimento assintótico estimado para S. notomelas foi de 35,8 mm e o fator de condição apresentou maiores valores na primavera e verão e o recrutamento variando sazonalmente foi maior no outono e inverno. A taxa de crescimento para S. notomelas foi elevada (k=1,05), assim como a taxa de mortalidade natural (M=1,61), enquanto a longevidade foi baixa (2,85 anos). Sendo assim, observou-se que a espécie apresentou crescimento alométrico, com influência sazonal no recrutamento e fator de condição. Palavras-Chave: Ecologia populacional, Peixes, Parâmetros de crescimento, Sazonalidade, Rrecrutamento, Mortalidade. Introdução A diversidade de espécies da ictiofauna neotropical, estimada em cerca de 8000 espécies (Vari & Malabarba, 1998; Lundberg et al. 2000), com cerca de 4500 já conhecidas (Lévêque et al. 2008), e com grande diversificação de grupos funcionais ainda é um dos grandes desafios da ictiologia, sendo que muitas espécies, Pan-American Journal of Aquatic Sciences (2009), 4(3): 271-278 272 principalmente de pequeno porte, são praticamente desconhecidas, tanto do ponto de vista taxonômico, quanto de suas características biológicas. A ordem Characiformes é o grupo de peixes neotropicais com maior diversidade de espécies (Lévêque et al. 2008), formas e comportamentos, com mais de 1500 espécies descritas até o momento. Apesar da sub-família Cheirodontinae ser um dos grupos de Characidae mais bem conhecidos, em termos de filogenia e taxonomia (Malabarba, 2003; Hirano & Azevedo, 2007; Bührnheim et al. 2008), o número de estudos analisando aspectos da ecologia ainda é escasso. Entre os estudos realizados sobre aspectos da biologia de espécies de Cheirodontinae destacamse os realizados na região sul do Brasil. Gelain et al. (1999) analisaram a biologia reprodutiva de Serrapinnus calliurus no arroio Ribeiro (RS); Oliveira et al. (2002) analisaram o período de desova e fecundidade de Cheirodon ibicuhiensis, também no arroio Ribeiro (RS); Silvano et al. (2003) analisaram a fecundidade e período reprodutivo de Serrapinnus piaba no rio Ceará Mirim, (RN); Hirano & Azevedo (2007) analisaram a alimentação de Heterocheirodon yatai na bacia do rio Uruguai. Diversos autores têm estudado espécies de pequeno porte na bacia do Alto Rio Paraná (Braga & Gennari-Filho 1990, Garutti & Figueiredo-Garutti 1992; Giamas et al. 1992; Benedito-Cecilio et al. 1997; Lizama & Ambrosio 1999; 2002; Piana et al. 2006), no entanto, poucos trabalhos foram realizados em riachos com espécies de Cheirodontinae. Ainda que, para Serrapinnus notomelas destacam-se alguns trabalhos, tais como os de Lizama & Ambrosio (1999, 2002) sobre a relação peso/comprimento e fator de condição na planície alagável do rio Paraná, bem como o trabalho de Piana et al. (2006) quantificando a importância de características bióticas e abióticas sobre a densidade populacional de S. notomelas, na planície de inundação do rio Paraná. Por outro lado, Súarez et al. (2007) quantificaram a importância das características hidrológicas sobre a ocorrência de S. notomelas e constataram que esta espécie tem preferência por locais com baixa velocidade da correnteza e profundidade. Lourenço et al. (2008) analisaram aspectos da relação peso/comprimento, mortalidade e recrutamento em riachos da porção inferior do rio Ivinhema. Desta forma, à despeito da ampla distribuição das espécies de Cheirodontinae os estudos das características populacionais destas espécies se restringe basicamente à alimentação e sazonalidade da reprodução e na bacia do rio Paraná restringem-se basicamente à planície alagável dos R. S. BENITEZ & Y. R. SUAREZ grandes rios. Assim, para melhor compreensão do papel das características ambientais sobre a ecologia destas espécies, que estão entre as mais comuns nos riachos da bacia do rio Paraná-MS, ainda são necessários mais estudos. O presente trabalho tem como objetivo fornecer informações sobre a estrutura em comprimento, a relação peso total/comprimento padrão, parâmetros de crescimento, mortalidade e analisar a influência da variação sazonal da precipitação sobre o peso médio dos indivíduos e o padrão de recrutamento em um riacho de primeira ordem na bacia do rio Dourados, Alto Rio Paraná, Mato Grosso do Sul. Material e Métodos As coletas foram realizadas mensalmente no córrego Chico Viégas, Dourados-MS (Fig. 1) entre outubro/2006 e setembro/2007, realizadas com uma peneira retangular de armação metálica (1,2 x 0,8 m) confeccionada com tela mosquiteiro (2 mm de abertura de malha), as amostragens foram realizadas no período diurno em um trecho de aproximadamente 200 m. O trecho amostrado encontra-se na área peri-urbana da cidade de Dourados, sem vegetação ciliar e com predomínio de gramíneas em suas margens e o esforço de amostragem não foi padronizado, visando obter número suficiente de indivíduos em todos os meses, mesmo quando a densidade da espécie era baixa. Em campo, os peixes foram fixados em formol a 10% e posteriormente foram levados ao laboratório e transferidos para álcool 70% para preservação e posterior obtenção do peso em balança analítica e do comprimento padrão, utilizando paquímetro com precisão de 1 mm. A relação peso total/comprimento padrão para S. notomelas foi obtida através do ajuste de um modelo de regressão não-linear, bem como o intervalo de confiança para o coeficiente angular “b” da regressão. O comprimento assintótico foi estimado a partir do maior individuo capturado utilizando a equação de Pauly (1983): L∞ = Lmax / 0,95 . O valor estimado da taxa de crescimento (k) foi obtido utilizando-se o método ELEFAN I (Eletronic Lengths-Frequency Analysis) (Pauly & David, 1981), inserido no programa FISAT. O índice de performance de crescimento (φ) foi obtido para a espécie através da equação proposta por Pauly & Munro (1984): ϕ = log k + 2 log L∞ enquanto a longevidade foi estimada segundo a equação proposta por Taylor (1958): t max = to + 2,996 / k . Pan-American Journal of Aquatic Sciences (2009), 4(3): 271-278 Biologia populacional de Serrapinnus notomelas na bacia do rio Dourados, Alto rio Paraná A mortalidade total (Z) aqui definida como igual à mortalidade natural (M), foi obtida segundo a fórmula empírica de Pauly (1980) que utiliza a informação dos parâmetros de crescimento (L ∞ e k) e a temperatura média (°C) do ambiente em que a espécie foi coletada ln M = −0,0152 − 0,279 ln L∞ + 0,6543ln k + 0,463ln T °C. Com o objetivo de analisar a influência da variação temporal sobre o peso dos indivíduos, foi realizada uma análise de variância do fator de condição (variável resposta) em função do mês da amostragem (variável explanatória). O fator de condição foi obtido através da equação FC=Peso 273 total/Comprimento padrãob. O padrão de recrutamento foi obtido através da distribuição de freqüência bimestral de comprimento padrão e dos parâmetros de crescimento (L ∞ e k) estimados para a espécie, e para tal utilizou-se a rotina incluída no FISAT (Gayanilo & Pauly, 1997). Tanto os dados de fator de condição ao longo do ano quanto o padrão de recrutamento foram contrastados graficamente com os dados de pluviosidade acumulada mensal, temperatura média do ar e comprimento do dia (horas com sol), com dados fornecidos pela EMBRAPA/CPAO. Figura 1. Mapa com a localização da área de estudo no córrego Chico Viégas, Bacia do rio Dourados, Alto rio Paraná, MS Resultados Foram obtidos dados de peso e comprimento de 464 indivíduos de Serrapinnus notomelas. O número de indivíduos coletados variou ao longo do ano, com menor número de indivíduos coletados no período seco (Média(outubro-março)=61,2±49,5; Média(abril-setembro)=16,2±8,1), apesar do aumento no esforço de captura. O comprimento padrão médio foi 26,2 mm (dp=4,31), variando entre 12 e 34 mm. O peso total médio foi 0,24 g (dp=0,14), variando entre 0,005 e 0,736g (Fig. 2). Utilizando os dados de comprimento padrão, foi possível prever com precisão de 81,1% o peso dos indivíduos, sendo que o modelo gerado para S. notomelas foi Peso total=0,00000077*Comprimento padrão3,83, como o intervalo de confiança estimado para o coeficiente angular da regressão variou entre 3,60 e 4,06 (α=0,05) constatou-se que a população estudada apresenta crescimento alométrico positivo (Fig. 3). Estimou-se o comprimento assintótico para S. notomelas em 35,8 mm, enquanto a mortalidade natural (Z) foi estimada em 1,61 ano-1 e taxa de crescimento (k) em 1,05 ano-1 com longevidade estimada em 2,85 anos. O Índice de performance de crescimento (φ) calculado para S. notomelas foi de 3,129. Constatou-se, através da análise de variância, que existe influência significativa da variação sazonal, sobre o fator de condição de S. notomelas (r2=0,438; F11,452=32,01; P<0,001), sendo que o fator de condição apresenta os maiores valores no início do período de seca (Abril a Junho). O pico de recrutamento para S. notomelas também ocorreu no mesmo período (Fig. 4), sugerindo maior intensidade na reprodução e, sendo assim, o aumento de peso indica o maior desenvolvimento gonadal, acompanhado da entrada de juvenis Pan-American Journal of Aquatic Sciences (2009), 4(3): 271-278 274 na população. Através da analise gráfica da variação no fator de condição e do padrão de recrutamento constatamos que ambos os parâmetros populacionais R. S. BENITEZ & Y. R. SUAREZ apresentaram correlação com a pluviosidade, sendo que ambos aumentaram no final do período chuvoso e com redução de temperatura e comprimento do dia. Figura 2. Histograma de freqüência para comprimento padrão (mm) e peso total (g) para S. notomelas no córrego Chico Viégas no período de outubro/2006 a setembro/2007. Figura 3. Relação Peso total/Comprimento padrão para S. notomelas no córrego Chico Viégas no período de outubro/2006 a setembro/2007. Pan-American Journal of Aquatic Sciences (2009), 4(3): 271-278 Biologia populacional de Serrapinnus notomelas na bacia do rio Dourados, Alto rio Paraná 275 Figura 4. Relação entre o fator de condição (*1.000.000) e o recrutamento de S. notomelas com a temperatura média do ar (°C), pluviosidade acumulada mensal (mm) e tempo médio diário de radiação entre outubro/2006 e setembro/2007 no córrego Chico Viégas, Alto rio Paraná, MS. Discussão A estrutura em comprimento de uma população varia devido ao regime de recrutamento e mortalidade dos indivíduos. As alterações na estrutura em comprimento podem resultar do efeito das variáveis abióticas e bióticas na taxa de natalidade e sobrevivência de cada população (Gurgel 2004), da variação dos atributos ambientais, que determina o estado nutricional da população (Bagarinão & Thayaparam 1986). Lizama & Ambrósio (1999) estimaram, na planície de inundação da bacia do rio Paraná, que S. notomelas apresentava o coeficiente angular da regressão “b” igual a 3,09, menor do que encontrado no presente estudo. Resultado similar foi encontrado por, Lourenço et al. (2008), em riachos da porção inferior da bacia do rio Ivinhema, onde o valor estimado foi de 3,08. Assim, ambos os trabalhos, e nossos dados, mostram que esta espécie apresenta crescimento alométrico positivo, o que é relativamente esperado dado o fato desta ser uma espécie forrageira, que deve alcançar o comprimento máximo o mais rápido possível visando minimizar a chance de serem predados (Reznick et al. 1996). Contudo, no presente estudo constatamos que a população analisada apresenta maior taxa de mortalidade e taxa de crescimento, bem como uma menor longevidade. Strauss (1990) analisando a influência das características ambientais e da intensidade da predação sobre os parâmetros de história de vida de Poecilia reticulata constatou que a elevada predação influenciou significativamente as características das populações analisadas, bem como a variabilidade ambiental. Neste sentido é plausível supor que diferenças hidrológicas entre as porções média e inferior da bacia do rio Ivinhema, como temperatura, variabilidade na vazão, características físicas e Pan-American Journal of Aquatic Sciences (2009), 4(3): 271-278 276 químicas da água, possam interferir nas características populacionais avaliadas, diminuindo a longevidade e conduzindo a uma maior taxa de crescimento e mortalidade para a população analisada. Assim, considerando a ampla distribuição desta espécie na bacia do Alto Rio Paraná, é esperado que esta apresente uma razoável plasticidade fenotípica, o que permite que diferentes sub-populações expressem diferenças nos estimadores dos parâmetros populacionais, como resultado de diferenças nas características hidrológicas entre as regiões estudadas. Durante as amostragens, duas espécies predadoras foram coletadas, sendo Hoplias malabaricus e Crenicichla britskii, o que, considerando o baixo volume do riacho amostrado permite sugerir que a taxa de predação sobre a população estudada deva ser elevada, corroborando a hipótese de rápido crescimento como estratégia de maximização do sucesso reprodutivo. De forma complementar, outra explicação para a elevada taxa de crescimento e mortalidade para a população estudada é a imprevisibilidade ambiental (estocasticidade) do riacho amostrado, uma vez que normalmente riachos de cabeceira são sujeitos a variações abruptas nas suas características hidrológicas, o que influencia inúmeras características evolutivas das comunidades de peixes (Castro, 1999) e poderia influenciar a dinâmica populacional das espécies aquáticas residentes e principalmente S. notomelas, dada a sua predileção por ambientes mais calmos, ou seja, menor velocidade da correnteza e menor profundidade (Súarez et al. 2007). O claro padrão sazonal no fator de condição para a população estudada de S. notomelas, pode ser resultado da sua predileção por menores valores de velocidade da correnteza (Súarez et al. 2007), que atuaria com maior intensidade sobre os juvenis, assim a concentração da reprodução neste período poderia maximizar o sucesso reprodutivo, por minimizar a mortalidade nos primeiros estágios de desenvolvimento dos juvenis. Como o pico de recrutamento também ocorre neste período, é provável que, apesar da redução do número de indivíduos, ocorra a interação entre a reprodução e a colonização do trecho amostrado por indivíduos juvenis provenientes de ambientes mais favoráveis à jusante, em pequenas área de planície alagável, muito comuns nos riachos da região. Lizama & Ambrósio (2003) evidenciaram que o recrutamento de Moenkhausia intermedia é continuo e presente durante todo o ano, na planície de inundação do rio Paraná, embora ocorram R. S. BENITEZ & Y. R. SUAREZ períodos de maiores intensidades. Este padrão de recrutamento observado é característico de espécies de pequeno porte que habitam ambientes de água doce em regiões tropicais. Além disso, os picos de recrutamento na sua grande maioria coincidem com o período de mudança no nível da água, o que é condizente com nossos resultados. Na porção inferior do rio Ivinhema, Lourenço et al. (2008) também constataram maior recrutamento de S. notomelas no período com menor pluviosidade, porém com dois picos no ano, uma vez que o mês de abril apresentou um pico de pluviosidade que diminuiu o recrutamento. Desta forma, a hipótese de correlação negativa entre a pluviosidade e recrutamento é corroborada mais uma vez. Desta forma, o presente trabalho sugere que no Córrego Chico Viégas, Alto Rio Paraná, S. notomelas apresenta crescimento alométrico positivo, maior taxa de crescimento e de mortalidade, quando comparado às porções inferiores da bacia, e clara variação sazonal no fator de condição e no padrão de recrutamento. Estes resultados parecem refletir alguns aspectos básicos da biologia da espécie: 1) Alta taxa de crescimento como estratégia de compensação da elevada taxa de mortalidade e baixa longevidade, possivelmente como decorrência da predação ou de eventos estocásticos sobre a população e 2) A variação no fator de condição e no padrão de recrutamento pode ser uma resposta à maior fragilidade dos juvenis à elevada velocidade da correnteza e a entrada de indivíduos juvenis na população, indicando ou a atividade reprodutiva neste período ou a colonização por juvenis provenientes de trechos a jusante. Agradecimentos: A UEMS pelo apoio logístico. A Edmara G. Barbosa, Sabrina B. 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Neotropical Ichthyology: An Overview. Pp. 1-12. In: Malabarba, L. R., Reis, R. E., Vari, R., Lucena, Z. M. S. & Lucena, C. A. S. (Eds.). Phylogeny and Classification of Neotropical Fishes. 1 ed. Porto Alegre, Brasil: EDIPUCRS, 603 p. Received April 2009 Accepted July 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 271-278 Scientific Note New records of the brachyuran crabs Hepatus pudibundus (Aethridae) and Persephona mediterranea (Leucosiidae) in their southernmost Western Atlantic distribution GASTÓN MARTÍNEZ1, FABRIZIO SCARABINO1, 2 & ESTELA DELGADO3 1 Dirección Nacional de Recursos Acuáticos, Constituyente 1497, P.O. Box 11200, Montevideo, URUGUAY. Email: gmartinez@dinara.gub.uy 2 Museo Nacional de Historia Natural y Antropología, C. C. 399, P.O. Box 11.000, Montevideo, URUGUAY. Email: fscara@gmail.com 3 Instituto de Investigaciones Pesqueras, Facultad deVeterinaria. Tomás Basañez 1160, P.O. Box 11300. Montevideo, URUGUAY. Email: estela@fcien.edu.uy Abstract. New findings as well as biological data on the presence of the brachyurans Hepatus pudibundus and Persephona mediterranea in the Uruguayan shelf are recorded and discussed. Both species have their southernmost limits there, where their occurrences have increased in the last 10 years. Keywords: Uruguayan shelf, subtropical species, Decapoda, Brachyura. Resumen. Nuevos registros de los cangrejos braquiuros Hepatus pudibundus (Aethridae) y Persephona mediterranea (Leucosiidae) en el extremo sur de su distribución en el Atlántico Occidental. Se registran y discuten nuevos hallazgos así como información biológica sobre la presencia de los cangrejos braquiuros Hepatus pudibundus y Persephona mediterranea en la plataforma uruguaya. Ambas especies tienen su límite sur de distribución aquí, donde su ocurrencia ha aumentado en los últimos 10 años. Palabras clave: Plataforma uruguaya, especies subtropicales, Decapoda, Brachyura. Living mostly in tropical waters, the brachyuran crabs of the families Aethridae and Leucosiidae are very scarcely represented south of Santa Catarina State, Brazil (28ºS) (Zolessi & Philippi 1995, Melo 1996, Spivak 1997, Boschi 2000). Hepatus pudibundus (Dana, 1851) (Brachyura, Aethridae) (see Ng et al. 2008) is found from Guinea to southern Africa in the East Atlantic Ocean; and from Georgia (USA) to Rio Grande do Sul (Brazil) in the West Atlantic Ocean (Melo 1996). Juanicó (1978) registered the first and yet only detailed record for Uruguayan waters. The geographic distribution range for Persephona mediterranea (Herbst, 1794) (Brachyura, Leucosiidae) is from New Jersey (USA) to Uruguay (Coelho & Torres 1980, Bordin 1987, Melo 1996). However, these reports did not provide detailed data about the material collected in Uruguayan waters. For both species there is no other available information on their southernmost Western Atlantic distribution. Here we report and discuss new findings of these species in Uruguayan waters based on several sources, including benthic surveys and occasionally collected material washed ashore. The first source includes a) fishing trip (June 2003) using a clam dredge, b) scientific survey using a beam trawl (November 2006) and a Spatangue dredge (April 2007) and c) fishing (October 2006) and scientific survey (January 2007) using a shrimp trawl. Incidentally captured specimens during the fisheries monitoring program of DINARA (Dirección Nacional de Recursos Acuáticos) (December 2002 and April 2007) using an Engel Pan-American Journal of Aquatic Sciences (2009), 4(3): 279-282 280 G. MARTINEZ ET AL. gonad development stage according to Reigada & Negreiros-Fransozo (2000). For H. pudibundus, juveniles were considered after Mantelatto & Fransozo (1994) who established the morphologic sexual maturity at 32 - 34 mm of CW. Total samples or voucher specimens were deposited in the Museo Nacional de Historia Natural y Antropología (MNHNM, Montevideo, Uruguay). Hepatus pudibundus, including adults and juveniles (Table II), was found washed ashore (8 dead specimens) and between 5 and 31 m depth (Fig. 1), and mainly occurring in fine sands. From 12 females dissected, one was immature, two has rudimentary gonads, three were in intermediary stage and six presented developed gonads; one ovigerous female was found (September). From 12 males dissected, one resulted immature, five presented rudimentary gonads, two had developing gonads and two presented already developed gonads. Two specimens (a male and a female) were found immature despite being larger than 34 mm. Morphometric and weight data registered here were in accordance with Mantelatto & Fransozo (1992, 1994) for Brazilian specimens. trawl were also considered (Table I). Bathymetric and sediment information was taken from scientific surveys. Table I. Number of crabs analyzed (collected) for H. pudibundus and P. mediterranea, washed ashore (dead) and by each sampling procedure. H. pudibundus P. mediterranea Washed ashore 8 3 Beam Trawl 9 13 Shrimp trawl 6 2 Engel Trawl 12 25 Clam Trawl 27 22 Total 62 65 Individual morphometric data (0.01 mm) and wet weight (0.001 g) were registered. Measures of carapace width (CW: greatest width), abdomen width (AW: width of fifth abdominal somite), and chela length (CHL: propodus length) were taken. All captured crabs in the fishing trip (June 2003) of H. pudibundus were dissected in order to assess their Table II. Ranges of individual morphometric data (mm) (CW: carapace width, AW: abdomen width and CWL: chela length) and wet weight (g) (WW), discriminated by sex for H. pudibundus and P. mediterranea and by state of maturity for H. pudibundus. The number of specimens is between parentheses. NA means not available. Hepatus pudibundus Females (22) Persephona mediterranea Males (35) Females (26) Males (38) Juveniles (2) Adults (20) Juveniles (12) Adults (23) CW 29.68 – 34.21 40.35 – 60.72 6.08 – 33.98 47.50 – 73.68 27.59 – 38.76 4.30 – 42.83 AW 5.68 – 9.36 11.27 – 18.51 0.50 – 4.30 6.41 – 11.13 17.81 – 28.84 0.80 – 8.87 CWL 11.84 – 13.74 17.30 – 26.15 2.60 – 14.42 21.53 – 39.13 20.87 – 30.02 1.10 – 38.72 WW 7.24 – 9.27 17.05 – 44.16 NA – 7.65 25.03 – 68.23 9.38 – 26.39 < 1.00 – 30.01 Persephona mediterranea was found washed ashore (3 dead specimens) and between 5 and 28 m depth (Fig. 1), including a wide range of sizes (Table II) and occurred in fine sands. Two ovigerous females were found (January). The morphology of this species makes difficult the macroscopic assessment of the gonad development stage of the individuals, which should be carried out based on histological studies. The bathymetric range and sediment preferences of H. pudibundus and P. mediterranea registered in the Uruguayan waters fits within the already known for these species (see Mantelatto et al. 1995, Melo 1996, Bertini et al. 2001). Hepatus pudibundus and P. mediterranea are very distinctive species, having singular morphological and chromatic features among the Uruguayan carcinofauna that diminishes the possibilities of being overlooked and enhances interest of occasional collections. In this sense, although being aware of the different effort of sampling, we detected a progressive colonization of both species into the Uruguayan coast. In fact, these were not cited by Barattini & Ureta (1961), which includes all distinctive brachyurans known to be washed ashore there, as are present cases. Furthermore, none were recorded by Itusarry (1984), who considered the decapod fauna of the zone inhabited by these species. Finally, no specimen was brought to the collections and/or researchers along the 80´ and 90’. Since a few years (2000-2001) H. pudibundus and P. mediterranea started to be Pan-American Journal of Aquatic Sciences (2009), 4(3): 279-282 281 New records of brachyuran crabs in their southernmost Western Atlantic distribution southern Brazil coast may account for at least part of the Uruguayan populations, which in turns is responsible for the colonization of these warm water species. Further research need to be done concerning abundance, life history and reproductive biology of these crabs at the edge of their southern distribution. Our findings further highlight the importance of monitoring the Uruguayan coast, which is the southernmost limit for many warm water species in accordance to the influence of Subtropical Waters (see e.g. Ortega & Martínez 2007). This is of particular interest here in a Global Warming scenario, where extreme oceanographic events (see e.g. Demicheli et al. 2006) may contribute not only to eventual colonization but to definitive establishment of a given species. 59º 33º 57º 55º 53º 33º BRASIL URUGUAY La Coronilla Santa Teresa DE Piriápolis Punta del Este LA PL AT A 5m 10 35º m ATLANTIC OCEAN ARGENTINA 20 37º 59º 57º m 50 m 55º 10 0m m RÍO 35º 20 0 usually collected in the Uruguayan coast, and even known by local fishermen whom already refer to these crabs using common names. In this sense, H. pudibundus and P. mediterranea are called “cofresito” (litlle coffer) and “San Antonio” (leaf beatle – Coleoptera-Chyrsomellidae) respectively, given the most remarkable morphological and chromatic features of each one. Furthermore, both species (especially H. pudibundus) has been brought to our attention in recent years during stomach content analysis of the Patagonian smoothhound (Mustelus schmitti) and loggerhead turtles (Caretta caretta) from the Uruguayan inner shelf (Karumbé and Gatuzo Projects, pers. comm.). Mañé-Garzón (1968) and Milstein et al. (1976) reported Persephona punctata (Linnaeus, 1758) for the Uruguayan coast based on two specimens collected in the inner shelf. This species was otherwise cited as having the coast of Rio Grande do Sul (Brazil) as it southern limit of distribution (Bordin 1987, Melo 1996). We examined those two specimens (MNHNM 409 and 1222, respectivelly), which are juveniles (CL: 11.63 and 11.83 mm) without traces of chromatic design of P. mediterranea. The distinguishing characters between P. punctata and P. mediterranea (see Melo 1996) are difficult to assess in juvenile fixed specimens. In fact, some of the juveniles we collected and positively identified alive as P. mediterranea, had their marmorations vanished only few weeks after being fixed in formaline and preserved in alcohol. However, Mañé-Garzón (1968) mentioned orange symetrical spots for his specimen, which must therefore be referred to P. mediterranea. The identity of the specimen listed by Milstein et al. (1976) remains uncertain, as the presence of P. punctata in Uruguayan coast. The reidentification of Mañé-Garzón´s specimen as Persephona mediterranea indicates the finding of this species in Uruguayan coast in 1963. The previous record of H. pudibundus is based on one specimen (MNHNM 1530) collected in 1976 (Juanicó 1978) and an additional specimen (MNHNM 1627) was found as being collected in the same opportunity; both are adult specimens. These findings indicate the presence, at least intermittently, of both species since that time. However, the material here reported confirms these species as established in the Uruguayan coast. Although we found ovigerous females, it is unknown if these finally implies successful recruitment for the local population. Given the ingression of subtropical water mixtured with coastal waters it is not unlikely that a larvae supply of slightly northern locations in 37º 53º Figure 1. Sampling areas: (U) for P. mediterranea, () for H. pudibundus, (●) for both species and (○) localities where carapaces and dead crabs were found washed ashore. Acknowledgements We are grateful to the following people and institutions for kind cooperation in the field or for put at our disposal material collected during their own projects: A. Carranza, C. Clavijo, E. Chiesa, J Chocca, J. P. Lozoya, P. Puig, G. Riestra, A. Segura, Karumbé and Gatuzo Projects, A. & F. Toscano and Centro de Estudios de Ciencias Naturales. For species identification we thank A. Franzoso. For kind reply to our inquires or requesting of literature we also thanks A. Franzoso, G. A. S. de Melo and M. Juanicó. We finally acknowledge the work of three anonymous reviewers who improved the text. References Barattini, L. P. & Ureta, E. H. 1961. La fauna de las costas del este (invertebrados). Publicaciones de Divulgación Científica. Museo “Damaso Antonio Larrañaga”, Montevideo. 195 p. Pan-American Journal of Aquatic Sciences (2009), 4(3): 279-282 282 Bertini, G., Fransozo, A. & Costa, R. C. 2001. Ecological distribution of three species of Persephona (Brachyura: Leucosiidae) in the Ubatuba region, São Paulo, Brazil. Nauplius, 9(1): 31-42. Bordin, G. 1987. Brachyura da plataforma continental do estado do Rio Grande do Sul, Brasil e áreas adjacentes (Crustacea, Decapada). Iheringia, Serie Zoologia, 66: 332. Boschi, E. E. 2000. Species of decapods crustaceans and their distribution in the American marine zoogeographic provinces. Revista de Investigación y Desarrollo Pesquero, 13: 7136. Coelho, P. A. & Torres, M. F. A. 1980. Zoogeografía marinha do Brasil. II – Considerações ecológicas e biogeográficas sobre a família Leucosiidae (Decapoda, Brachyura). Revista Nordestina de Biologia, 3(especial): 67-77. Demicheli, M., Martínez, A., Ortega, L., Scarabino, F., Maytía, S. & Demicheli, A. 2006. Mass stranding of Argonauta nodosa Lightfoot, 1786 (Cephalopoda, Argonautidae) along the Uruguayan coast (southwestern Atlantic). Revista de Biología Marina y Oceanografía 41(2): 147-153. Itusarry, E. 1984. Taxonomía y distribución de los crustáceos (Decápodos) en el Frente Marítimo Uruguayo para los meses de febrero y marzo de 1982 (Cruceros 8201-8205) del B/P Lerez. Tesis de Licenciatura en Oceanografía Biológica, Facultad de Humanidades y Ciencias (Universidad de la República) Montevideo (unpublished). Juanicó, M. 1978. Ampliación de la distribución geográfica de tres especies de Brachyura (Crustacea Decapoda) para aguas uruguayas. Iheringia, Série Zoologia, 51: 45-46. Mantelatto, F. L. M. & Fransozo, A. 1992. Relação peso/largura da carapaça no caranguejo Hepatus pudibundus (Herbst 1785) (Crustacea, Decapoda, Calappidae) na região de Ubatuba, SP, Brasil. Arquivos de Biologia e Tecnologia, 35(4): 719-724. Mantelatto, F. L. M. & Fransozo, A. 1994. Crescimento relativo e dimorfismo sexual em Hepatus pudibundus (Herbst, 1785) G. MARTINEZ ET AL. (Decapoda, Brachyura) no litoral norte paulista. Papéis Avulsos de Zoologia, 39(4): 33-48. Mantelatto, F. L. M., Fransozo, A. & Negreiros Fransozo, M. L. 1995. Distribuição do caranguejo Hepatus pudibundus (Herbst, 1785) (Crustacea, Decapoda, Brachyura) na Enseada da Fortaleza, Ubatuba (SP), Brasil. Boletim do Instituto Oceanográfico, 43(1): 51-61. Mañé-Garzón, F. 1968. Persephona punctata punctata (L) (Decapoda, Brachyura), de la costa oceánica uruguaya. Revista de la Sociedad Uruguaya de Entomología, 7: 6265. Melo, G. A. S. 1996. Manual de identificação dos Brachyura (Caranguejos e Siris) do litoral Brasileiro. Plêiade/FAPESP Ed., São Paulo, 604 p. Milstein, A., Juanicó, M & Olazarri, J. 1976. Algunas asociaciones bentónicas frente a las costas de Rocha, Uruguay. Resultados de la campaña del R/V Hero, viaje 72-3ª. Comunicaciones de la Sociedad Malacológica del Uruguay, 4(30): 143-164. Ng, P.K.L., Guinot, D. & Davie, P.J.F. 2008. Systema Brachyurorum: Part 1. An Annotated checklist of extant Brachyuran crabs of the world, Raffles Bulletin of Zoology, Supplement Series (17), 286 p. Ortega, L. & Martínez, A. 2007. Multiannual and seasonal variability of water masses and fronts over the Uruguayan shelf. Journal of Coastal Research, 23(3): 618-629. Reigada, A. L. D. & Negreiros-Fransozo, M. L. 2000. Reproductive cycle of Hepatus pudibundus (Herbst, 1785) (Crustacea, Decapoda, Calappidae) in Ubatuba, SP, Brazil. Revista Brasileira de Biologia, 60(3): 483-491. Spivak E. D. 1997. Los crustáceos decápodos del Atlántico sudoccidental (25º - 55º S): distribución y ciclos de vida. Investigaciones Marinas, 25: 69-91. Zolessi, L. C. & Philippi, M. E. 1995. Lista sistemática de Decapoda del Uruguay (Arthropoda: Crustacea). Comunicaciones Zoológicas del Museo de Historia Natural de Montevideo, 12(183): 1-24. Received April 2009 Accepted July 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 279-282 Ballast water and sustainability: identification of areas for unballasting by geoprocessing — case study in Todos os Santos Bay, Brazil LUIZ JORGE SILVA TELES1,2 & CARLOS HIROO SAITO3 1 Department of Life Sciences at the State University of Bahia (Universidade do Estado da Bahia — UNEB); Address: Universidade do Estado da Bahia - UNEB, Departamento de Ciências da Vida - DCV, Campus I, Rua Silveira Martins, 2555, Cabula. Salvador, Bahia, Brasil. CEP: 41.150-000. Email: ljteles@uneb.br 2 Graduate Program in Sustainable Development, Center for Sustainable Development, Unversity of Brasilia (Programa de Pós-Graduação em Desenvolvimento Sustentável, Centro de Desenvolvimento Sustentável, Universidade de Brasília) Campus Universitário Darcy Ribeiro - Gleba A, Bloco C - Av. L3 Norte, Asa Norte – Brasília, Distrito Federal, Brasil. CEP: 70.904-970 3 Department of Ecology at the University of Brasília (Universidade de Brasília — UnB); Address: Universidade de Brasília, Departamento de Ecologia, Instituto de Ciências Biológicas, Campus Universitário Darcy Ribeiro, CX. Postal 04457, Brasília, Distrito Federal, Brasil. CEP 70.904-970. Email: carlos.saito@pq.cnpq.br; carlos.h.saito@hotmail.com Abstract. This study focuses on the GIS identification of areas recommended for unballasting in exceptional circumstances, within the 200 nautical miles of the coast, when vessels and/or travelers are exposed to high-risk situations, as a preliminary attempt to implement in advance some guidelines of the International Convention for the Control and Management of Ships’ Ballast Water and Sediments – 2004 (BWM). The Todos os Santos bay, located in the state of Bahia, Brazil, was chosen as a case study. The work starts with the definition of areas of exclusion, based on the identification of potential risk to urban areas, mangroves swamps, and nature conservation units, using as a parameter the speed of the water movement inside the bay. Overlaying the maps of areas susceptible to contamination by ballast water with thematic maps of water velocity and bathymetry, it was created a final map containing the areas recommended for unballasting of ships in exceptional circumstances. There, it was identified two contiguous regions (Area 1 with 16.19 km2 and Area 2 with 15.20 km2), being Area 2 more recommended for unballasting than Area 1. Keywords: Geoprocessing, Ballast Water, Environmental Management, unballasting. Resumo. Águas de lastro e sustentabilidade: identificação de áreas para deslastre por geoprocessamento – estudo de caso na Baía de Todos os Santos-BA, Brasil. O estudo trata da identificação, por geoprocessamento, de áreas com potencial de risco de contaminação ambiental por águas de lastro e áreas recomendadas para desastre em situações excepcionais, dentro das 200 milhas náuticas da costa, numa tentativa de avançar na operacionalização das diretrizes gerais da Convenção Internacional sobre controle e gestão de Água de Lastro e Sedimentos (BWM 2004). A Baía de Todos os Santos, Bahia – Brasil foi escolhida como estudo de caso. Inicialmente, procedeu-se à definição de áreas de exclusão baseadas na identificação de potencial de risco a áreas urbanas, áreas de manguezais e Unidades de Conservação, tomando-se como parâmetro a velocidade de deslocamento das águas no interior da baía. Cruzando-se o mapa de potencial de risco à contaminação por água de lastro, com os mapas de velocidade das águas e a batimetria, chegou-se ao mapa final de áreas recomendadas para deslastre de navios, em situações excepcionais. Foram identificadas duas áreas contíguas (Area 1 com 16.19 km2 e Area 2 com 15.20 km2), sendo a Area 2 mais recomendada para realização de deslastre que a Area 1. Palavras-Chave: Geoprocessamento, Água de Lastro, Gestão Ambiental, deslastre Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 284 Introduction The issue of sea pollution caused by maritime traffic has been debated more intensely since the intensification of commercial exchange by the end of the last century (Goldberg 1995, Elliot 2003). Among the many types of sea pollution, the one that has been drawing most attention is pollution resulting from the ballast water of ships. During the procedures of ballasting and unballasting, there is a transfer from one locality to another of contaminants and species of living beings, which include everything from viruses and bacteria to invertebrates, at a rate of between three to five billion tons of ballast water every year (Pollard & Hutchings 1990, Thresher 1999, Hayes & Sliwa 2003). This lead to the fear of the spread of epidemic diseases — such as cholera — and the outbreak of new epidemic diseases associated with the transport of microorganisms in ballast water. The epidemiological and environmental risk associated with the uncontrolled discharge of ballast water has become a source of growing concern among the governments of many countries. Just like the chemical pollutants, exotic invasive species are considered biological pollutants by Elliot (2003), which makes government of many countries to be increasingly geared to a measurable and anticipated form of detection of the risks involved. Thus, in this paper, the term “contaminants” in general also includes exotic invasive species and other harmful aquatic organisms and pathogens. In this context, the International Convention for the Control and Management of Ships’ Ballast Water and Sediments – 2004 (BWM) adopted in a Diplomatic Conference in February of 2004, is a very significant fact in environmental management in recent history. The BWM Convention objectives are “prevent, minimize and ultimately eliminate the risks to the environment, human health, property and resources arising from the transfer of Harmful Aquatic Organisms and Pathogens through the control and management of ships’ Ballast Water and Sediments, as well as to avoid unwanted side-effects from that control and to encourage developments in related knowledge and technology”. About the control and management of ships' ballast water and sediments in maritime transport, the BWM Convention requires that the change of the content of ballast water tanks should be carried out in oceanic waters. In other special cases, when the vessel is caught up in an emergency situation and the navigability of the ship or safety of the crew is at stake, a competent authority should indicate an appropriate place for unballasting without any impact or risk to either human health or the L. J. S. TELES & C. H. SAITO ecosystem. (Regulation B-4, paragraph 4: “A ship conducting Ballast Water exchange shall not be required to comply with paragraphs 1 or 2, as appropriate, if the master reasonably decides that such exchange would threaten the safety or stability of the ship, its crew, or its passengers because of adverse weather, ship design or stress, equipment failure, or any other extraordinary condition”). Once Brazil has a coastline extension of nearly 8,500 km and an economic partner to countries all over the world with intense and constant maritime port movement, it is a country highly exposed to the possible environmental dangers resulting from the unballasting of commercial ships, with emphasis in the marine concern. In this context, the purpose of the present work is a preliminary attempt to use a methodology based on geoprocessing to identify areas for the unballasting of ships under special circumstances and for their own safety, as were previewed in Regulation B-4, paragraph 4 of BWM Convention, taking the Todos os Santos bay, in the state of Bahia, Brazil, as case study. Thus, this study can be seen as an effort to prepare Brazilian government staff to handle GIS perspective in the control and management of ships' ballast water and sediments, considering the future entry into force of BWM Convention. Study Area. The Todos os Santos bay (TSB) occupies an area of approximately 1,000 km2 and has 184 km of continental coastal extension. The bay appears as a recess in the coastline by which the sea penetrates the continent, in the form of a channel between the city of Salvador and the island of Itaparica, in the state of Bahia. It has a width of nearly 9 km and a maximum depth of approximately 50 m, free of silting (CRA, 2001). Characterized by a variety of estuary plains, small inland bays, flooded estuaries and mangrove swamps surrounding it, the bay has a complex tributary drainage network, with a total area of approximately 60,500 km2. In spite of the fact that it faces a number of serious environmental challenges at specific points, the TSB has 54 islands and countless beaches around it, including 320 km of rocky sandy beaches that offer an indisputable tourist potential, all in an area that is well-served by a mesh of paved roads and easy access to the surrounding cities (CRA, 2001). Material and Methods Geoprocessing is a set of processes designed to support decision-making, logically and physically based on a technology known as Geographic Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 Identification of areas for unballasting by geoprocessing - case study in Todos os Santos Bay, Brazil Information Systems (GIS), a computational structure that allows for the storing, retrieving, handling, and outputting of georeferenced data (Tomlinson & Boyle 1971, Aronoff 1991), supporting both quantitative and qualitative analysis (Pavlovskaya, 2006). In order to identify areas recommended for unballasting, a general criteria structure is 285 presented in Figure 1, similar to presented in Wood & Dragicevic (2007), based on Malczewski (1999). As a multicriteria evaluation (MCE), it was assumed there is no weight differences among the criterion layers and they were just normalized by defining the same amplitude of ordering theoretical axis (Malczewski, 1999). Figure 1. Flow chart of the procedures for identification of areas recommended for unballasting of ships inside the TSB. The map of areas susceptible to contamination was get by overlapping three maps: proximity to urban areas, proximity to mangrove swamps, and proximity to nature conservation units (NCU). In every these three maps it was established a risk zone, corresponding to the capacity of a contaminant to reach a sensitive target land use. Each risk evaluation was done separately before being assessed in a integrated analysis procedure to produce a Map of areas susceptible to contamination. The risk zone was determined based on physical data (water circulation speed), devised to express the spreading capacity of the contaminating load coming from the discharge of ballast water by a ship. The map of water circulation speed at rising spring tide with cold front winds, produced by the CRA, was chosen as the basis for this study, due to the fact that under such conditions the water circulation speed is maximized, sustaining a conservative analysis. The velocity of water circulation at the entrance to the bay at flood tide, multiplied by the time it takes for the tide waters to alternate between rising tide and ebb tide makes it possible to calculate the maximum reach of a contaminant during a complete period of spring tide with cold front winds, considering the fact that the tides alternate between their rising tide flux and ebb tide flux every 06:21h (six hours and twenty-one minutes). The width of the proximity buffer to urban areas, mangrove swamps, and NCU corresponds to this maximum reach of a contaminant during a complete period of spring tide with cold front winds. Because of the generic character of this modelling process, it was not considered the possible influence of self movement of certain species or their larvae forms. In the same way, once it was proposed to locate the risk zone by the reach of water circulation speed, it was assumed that the contaminants body form or weight is negligible and Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 286 every contaminant can be carried out at the same speed of the water in which it is immersed. The robustness of this modelling procedure is based on a heuristic evaluation of the risk, based on the uncertainty of the effective contamination, which is incorporated by mapping the buffering zones of the grades of probable risk. The urban areas were selected in view of the possible impact on public health as the result of the presence of contaminants such as pathogenic microorganisms contained in the ballast water, which could lead to the outbreak of diseases transmitted in water, such as cholera, typhoid fever, and hepatitis A. In TBS, the urban areas area characterized as the projection of this area to TBS coastline, where it is situated all the beaches where people use for swimming, and it was done no distinction among these projections, considering that all of them had direct or indirect human contact. The mangrove swamps were chosen due to the fragility of these ecosystems and to the fact that they often are the reproduction sites for several marine organisms. Chemical contaminants present in ballast water could cause a serious damage to this very fragile ecosystem, besides the fact that the exotic invasive species contained in ballast water could upset the balance of the intricate web of ecological relationship among the species therein. Furthermore, the mangrove swamps, in contrast to the urban areas or the on-land NCU, suffer the direct impact of the contaminants found in ballast water because mangroves exist in an environment where water is a component, not only a contact medium. This was one more reason for choosing protection areas in the form of nature conservation units, to be mapped and evaluated in terms of areas of their proximity to ship L. J. S. TELES & C. H. SAITO unballasting. By realizing the need to harmonize environmental interests with socioeconomic ones, studies must be conducted to identify areas recommended for unballasting within the range of the 200 nautical miles of the coast, under exceptional circumstances, excluding the areas which have been mapped for potential risk of contamination, to avoid arbitrary unballasting in any area near the coast. This anticipatory attitude meets the demands of planning based on a diagnostic approach to the real situation, according to a sustainable development point of view. Moreover, this proposition also meets the Regulation B-4, paragraph 2, of the International Convention for the Control and Management of ships’ ballast water and sediment – 2004, which states that “In sea areas where the distance from the nearest land or the depth does not meet the parameters described in paragraph 1.1 or 1.2, the port State may designate areas, in consultation with adjacent or other States, as appropriate, where a ship may conduct Ballast Water exchange, taking into account the Guidelines described in paragraph 1.1”. To this end, the target of these areas should consider the greatest water circulation speed at ebb tide on the way out of the TSB, allowing for the greatest dilution of the contaminants present in the discharged ballast water and its quickest carrying away to open sea, far away from the coastline. On the map showing the depth of the bay (bathymetric map), the deepest areas were positively selected, because they provide the maximum height of water columns and thus the greatest potential for dilution of the contaminants. The definitive criteria adopted are described in Table I. Table I. Criteria used for classification on the map of areas recommended for ship unballasting. Variables represented on the maps Criteria for classification Depth Above 30 meters Speed Above 0.5 m/s Potential risk Medium, Low-Medium, and Low Based on the map of water circulation speed, some areas were positively selected, those where the water velocity corresponded to the highest speed within the amplitude range of the locality. This circumstance favors the dilution of the contaminants present in the discharged ballast water and a quicker carrying away of these contaminants to the open sea, far from the coast. On the map showing the depth of the sea at the bay (bathymetric data), the deepest areas were positively identified. The selection of areas with the greatest depth allows for the contaminants present in unballasted water to be diluted more easily, due to the greater height of the water column, thus minimizing the contamination risk potential. The overlaying of these two maps, cross-checked against the former map showing the areas susceptible to contamination, once again using Boolean analysis, led to the final map which shows the areas recommended for ship unballasting. Results The velocity of water circulation at the entrance to the bay at flood tide was determined as Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 Identification of areas for unballasting by geoprocessing - case study in Todos os Santos Bay, Brazil 0.5 m/s and the maximum spread of a contaminant during a complete cycle of spring tide with cold front winds was defined as 11,430 meters. This value was divided into three equal parts of 3,810 meters, to establish the areas of high, medium, and low risk potential in each proximity map: proximity to urban areas, to mangrove swamps, and to NCU. Farther than 11,430 meters, the potential risk would be null. The quantitative results — in terms of 287 territorial extension of each proximity zone on each map — are consolidated on Table II. So, after having started based on secondary governmental data, it was possible to proceed with the manipulation of the database in order to generate intermediary maps in the analysis structure presented in Figure 1. Those three maps overlaid, each given equal importance and analyzed according to the Boolean method, yielded a map of areas susceptible to contamination (Fig. 2). Table II. Territorial extension of each proximity zone on the resulting maps of proximity (to urban areas, mangrove swamps, and nature conservation units) in the interior of Todos os Santos bay (Bahia state, Brazil). Area between Area between Area from Maps of proximity 7.61 km and 11.43 3.81 km and 7.61 km 0 km to 3.81 km (km2) km (km2) (km2) To urban areas 761.2 714.2 419.8 To mangrove swamps 457.5 364.4 143.1 To nature conservation units 891.1 486.6 406.2 Figure 2. Map of areas susceptible to contamination (potential risk of contamination). That is, at each point on the map five categories of potential risk were determined: very high, high, medium, low-medium, and low susceptibility to contamination. The most susceptible areas to contamination (very high risk) would be those which simultaneously ranked in the high risk categories on all three maps of proximity to urban areas, mangrove swamps, and nature Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 288 conservation units. Accordingly, those areas that ranked in the low risk category on the three proximity maps would be classified as the areas as the lowest susceptible areas to contamination (low risk). These are the extremes of an orderly classificatory vector, where the intermediary classes are found. The complete criteria can be found on Table III and the width of the potential risk zones can be seen in Table IV. To identify the areas recommended for ship unballasting, the greatest water circulation speed at ebb tide on the way out of the TSB should be found. L. J. S. TELES & C. H. SAITO The velocity range chosen was the one higher than 0.5 m/s, on the map of water circulation speed at neap tide with normal winds (when circulation velocity is minimized). Also, the deepest areas were searched to provide the maximum height of water columns and thus the greatest potential for dilution of the contaminants: the regions chosen were those with a depth greater than 30 meters, which represents the greatest depth within the amplitude range of that locality. The final map of the areas recommended for ship unballasting was shown in Figure 3. Table III. Criteria adopted for the map of areas susceptible to contamination. Potential risk Criteria for classification Very high When the zones of greatest potential risk according to proximity (from 0 km to 3.81 km) overlaid each other on all three maps. High When two of the greatest potential risk zones according to proximity overlaid one another (from 0 km to 3.81 km). Medium Overlaying indicated one component in the range of 0 km to 3.81 km and two components in the range of 3.81 km to 7.61 km, or overlay showing the three components in the range of 3.81 km to 7.61 km. Low-Medium Overlay showing at least one component in the range of 3.81 km to 7.61 km. Low Overlay showing all components to be in the categories above 7.61 km. Table IV. The territorial extension of the susceptible areas to contamination in the study area. Classes of potential risk Within TSB (km2) Outside TSB (km2) Very high potential risk 295.80 0.00 High potential risk 418.60 162.40 Medium potential risk 268.50 362.10 Low-Medium potential risk 42.48 145.20 Low potential risk 0.00 954.90 1,025.38 1,624.60 Totals: In reality, the selected area is composed of two contiguous regions (1 and 2), which were chosen individually, then ranked between them according to the risk they presented due to their proximity to the interior of the TSB. Area 1 totals 16.19 km2 and Area 2 totals 15.20 km2. The two areas together total 31.39 km2. Area 2 is more recommended for unballasting than Area 1. The precise geographical localization is presented in Table V. Discussion The map of proximity to urban areas locates the cities surrounding the TSB, including Salvador and the other cities in the metropolitan region under its direct influence. The map of proximity to mangrove swamps points out the sensitive areas of what still remains under the protection of the Área de Proteção Ambiental da Baía de Todos os Santos (Environmental Protection Area of Todos os Santos bay). These preliminary pieces of information make it possible to identify potential risk areas, and in the case of the bay of Iguapé, these data could serve as the primary risk assessment tool for the Marine Extractivist Reserve of the Iguapé Bay (ExRes), in the districts of Maragojipe and Cachoeira. The map of proximity to nature conservation units was made based on the location of the state NCU (environmental protection areas of Abaeté, TSB, Joanes/Ipitanga, and Bacia do Cobre) — under the management of the CRA — and on the location of the ExRes, a federal NCU for sustainable use. The delimitation of the proximity zones surrounding the NCU, identifying those which represent potential risk of contamination to the coastal areas by ballast water, could provide valuable information for the preparation of the Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 289 Identification of areas for unballasting by geoprocessing - case study in Todos os Santos Bay, Brazil respective NCU management plan. This plan, despite being land-related, could help define “buffer zones,” including the contiguous marine portions therein, as areas regulated from the point of view of anthropic activities in order to minimize the impact on biodiversity within the NCU. Figure 3. Map showing the areas recommended for ship unballasting. Table V. The geographical localization of areas recommended for ship unballasting (UTM, SAD-69, zone 24). Geographical localization of Area 1 (UTM) Geographical localization of Area 2 (UTM) N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 X 546.765 547.255 548.679 549.253 549.318 549.017 548.966 548.408 548.253 548.157 547.926 548.381 548.326 548.476 546.765 Y 8.562.945 8.564.481 8.566.627 8.567.763 8.568.121 8.568.590 8.568.398 8.568.313 8.568.217 8.568.582 8.569.215 8.569.905 8.570.671 8.571.640 8.562.945 N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 X 545.416 546.094 547.661 547.598 547.492 547.515 547.282 546.965 546.945 547.009 547.243 547.519 547.561 547.985 548.303 545.416 Y 8.555.092 8.554.606 8.553.866 8.554.288 8.554.688 8.555.256 8.555.615 8.556.100 8.556.605 8.556.921 8.557.300 8.557.510 8.557.826 8.557.846 8.557.614 8.555.092 Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 290 Specifically in the case of the ExRes of Iguapé, the NCU management plan and the kinds of use of marine resources by the communities there settled depend on an evaluation of the potential risks to which they are susceptible. The vigilance exercised and even the social negotiation concerning the location of ship unballasting areas depend on the mapping of the zones of potential risks to which the marine resources of the ExRes and in particular the mangrove swamps therein are exposed. The map of areas susceptible to contamination (Fig. 2) clearly shows the fragility of the TSB in regard to contamination by ballast water. Inside it, there is no area free from the risk of contamination in limit-situations — that is to say, in the extreme case of quickest contaminant spread, as would occur at spring tide with cold front winds. The most critical areas, which are shown on this resultant map, are the ones which require the highest level of vigilance by competent authorities, in order to restrain the practice of ship unballasting. It must be emphasized that the study area comprises a large region outside the TSB, including the coastal portions to the south — close to the island of Itaparica — and to the north of the bay. According to these data, the greatest part of the interior of TSB is categorized as high or very high risk, whereas no region inside it could be classified as low risk, thus revealing the fragility of the bay in regard to the discharge of ballast water by ships. The large low risk areas in the region of the study are located outside of the TSB. The information generated by the study also provides valuable data for a coastal and marine ecological zoning; the areas in dark blue on the map of areas susceptible to contamination (Fig. 2) — a 3.81 km extension starting from the coastline — serve to outline the forbidden area, within which under no circumstances should the vessel perform unballasting. The areas in light blue constitute a moderate risk zone for unballasting. After having chosen the appropriate site for the unballasting procedure based on Figure 3, and following the parameters decided upon for this purpose, it is believed that the process should cause the minimum possible risk of environmental contamination to the interior waters of the TSB. In the recommended area, the vessels will only be able to carry out the unballasting at ebb tide, so that the possible contaminants are taken away by the sea currents towards the deeper waters away from the coastline, where there is a higher degree of resilience and no risk of contamination to inland TSB. Moreover, since the chosen water circulation speed is moderate, the vessels can function normally at the L. J. S. TELES & C. H. SAITO moment of unballasting, without fearing the sea currents that circulate with a greater force of the tide which might jeopardize the safety of the ship. The location of these areas should be previously communicated to the ships by the competent authorities, so that the ships that still have not followed the correct procedure — performing the unballasting process gradually during the journey — do so in the area specifically designated for unballasting with the minimum environmental impact possible. In fact, at the moment that the ships communicate the coordinates of their trajectory and/or of the scheduled unballasting, it is possible to compare those coordinates with the ones on the final map showing the areas recommended for ship unballasting. Then to judge, ad hoc, whether or not the ships have been operating according to the proper norms. Finally, the necessary adjustments regarding the location of the ship, by the retransmission of the correct coordinates with the location of the recommended areas for ship unballasting. It is hoped that there can be a conciliation of environmental concerns with prevention procedures at the time of unballasting in locations considered safe outside the TSB. In this way, the vessels which have not carried out the procedure during the journey can continue their trip performing their duty of transporting goods. Also, they can go on integrating national and international economies, within the perspective of sustainable development, independently of the application of the adequate punishments to those who have violated the IMO norms. Although this study was concluded in 2005, it seems still valid nowadays, even after the Resolution MEPC.151(55) – Guidelines on designation of areas for ballast water exchange (G14), adopted on 13 October 2006, which are created to support the already identified necessity for additional guidance on the designation of areas for ballast exchange, as stated by the Regulation B-4, paragraph 2, of the International Convention for the Control and Management of ships’ ballast water and sediment – 2004. According to this complementary guidelines, the identification of potential sea areas for ballast water exchange by a Port State requires consideration of legal aspects, important resources and protected areas, and navigational constraints. The G-14 is very clear in saying that “the location and size that provide the last risk to the aquatic environment, human health, property or resources should be selected for designation” (9.1). The identified ballast water exchange area(s) should be Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 Identification of areas for unballasting by geoprocessing - case study in Todos os Santos Bay, Brazil assessed in order to ensure that the designation will minimize any threat of harm to the environment, human health, property or resources taking into account but not limited to the following criteria: oceanographic (currents, depths), physico-chemical (salinity, nutrients, dissolved oxygen, chlorophyll 'a'), biological (presence of Harmful Aquatic Organisms and Pathogens, including cysts; organisms density), environmental (pollution from human activities), important resources (fisheries areas, aquaculture farms), ballast water operations (quantities, source, frequency). This assessment step follows the preliminary indication of area(s) promoted by this study and should be done by Port State to confirm the adoption of identified area(s) as official ballast water exchange area(s). Also, after the conclusion of the present manuscript, the Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) just recently adopted in its 56th session (9-13 July 2007) guidelines for additional measures regarding ballast waters management, including emergency situations (G13). In this guidelines, it is required the precise co-ordinates where and applicable date when additional measures are applicable by a Party to prevent, reduce, or eliminate the identified potential harm from the introduction of harmful aquatic organisms and pathogens in the area to be covered by the additional measures. This study in a certain way fits this guidelines, as gives the motivations to improve environmental protection, the conditions (emergency situations, at ebb tide, and inside the recommended areas 1 and 2) and the precise localization where the orientation should be performed. Conclusions and Recommendations In an attempt to locate geographically the susceptible areas to contamination from ballast water in the Todos os Santos bay, a wide range of data that were dispersed have been collected, organized, and presented, regarding urban areas and mangrove swamps, the location of federal and state nature conservation units, water circulation conditions, and bathymetry in the TSB. Geoprocessing has made it possible, through the cross-checking of several spatialized variables, to delimit an area of minimum environmental impact to be recommended to the competent authorities as the most suitable for ship unballasting, within the range of 200 nautical miles from the Brazilian coastline, in exceptional risk situations when the international norm of ship unballasting outside of the 200 nautical miles range cannot be followed. This work has also demonstrated that an 291 integrated management of both the coastal and marine zones, with regard to the challenge of ship unballasting, requires a coordinated, interdisciplinary effort, with the participation of sanitation, maritime, port, and environmental authorities, including environmentalists and NCU managers. Such a joint effort should result in a great accomplishment for the protection of the environment, while taking into account the operational expenses of the vessels, in order to avoid a negative economic impact on loading and unloading operations. Since the focus of this study has been on the Todos os Santos bay, the results apply locally and constitute the main source of data for both Agência Nacional de Vigilância Sanitária (Anvisa — National Sanitary Vigilance Agency) and the local port authority. Nevertheless, since the methodology can be extended to other port regions, it is hoped that it will serve as a starting point for a qualified and effective dialogue with Anvisa in order to prove that, besides the procedures adopted by the countries which have progressed in this area of environmental awareness, new contributions arising from the fundamentals of geoprocessing can be applied not only in the state of Bahia, but in other Brazilian ports as well. Further, the modelling procedure based on GIS, described in this study, can be continuously refined by the addition of new map layers or parameters, giving more accurate locations, reinforcing the directions described in the Guidelines on designation of areas for ballast water exchange (G14), adopted by IMO on 13 October 2006. It is now recommended that experimental field studies be conducted, in order to confirm the velocity of tide movements and the consequent transport of contaminants, as well as dispersion and dilution effects. These studies can contribute to the refining of the adopted model, to more accurately delineate the classification of the areas recommended in this study for ship unballasting. In addition, it is recommended to promote strategies for informing the social actors involved, so that the data about the location of the areas recommended for ship unballasting can be fully understood and assimilated. A wide but specific environmental education program shall be developed for all the social actors involved, complementary to the adoption of this kind of recommendation. This environmental education program can include themes about sustainability, individual and collective responsibility an ethics, besides the technical aspects of the ship unballasting and the prevention and minimization of the risks to the Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 292 environment, human health, property and resources arising from the transfer of Harmful Aquatic Organisms and Pathogens. It can also be recommended a special emphasis onto the vessels commanders, because of the Brazilian experience with informations received about the ballast water exchange performed by vessels. This information is based on an exploratory study intended to identify pathogenic agents in ballast water (General Management of Ports, Airports and Borders Project – GGPAF 2002, Brazil) carried out by the Agência Nacional de Vigilância Sanitária (Anvisa — National Sanitary Vigilance Agency) in 2002, involving nine Brazilian ports and a sample of 99 vessels of several nationalities with maritime transit in national and international ports. This study found that 62% of the vessels whose commanders declared to have performed ballast water exchange in oceanic waters probably did not actually do so, or did it only partially, which means an environmental risk (Anvisa 2003). This conclusion was reached based on the adoption of salinity measurements, which indicated that the salinity found in the ballast water of those ships did not correspond to the levels which were to be expected in oceanic waters. According to Anvisa, the salinity levels, which were less than 35%, pointed to the probability that there was a substitution of the ballast water near the coast, or near river estuaries, which results in a reduction of salinity because of the addition of fresh water. This means they can be aware of the recommendations to perform the replacement of ballast water in oceanic waters or even to perform the ballast water exchange in areas recommended for ship unballasting in emergency situations. Finally, the identification of possible unballasting areas near the coastline does not preclude the recommendation that, ideally, this procedure should be performed more than 200 nautical miles away from the coast, following the international guideline; nor should it hinder the search for alternative procedures, such as the installation of receptors of residuals like oil, ballast water, and other contaminants at the terminals, or the development of technologies for the decontamination of ballast tanks, ensuring both efficiency and safety, especially for the environment. Cautionary Notes. It is important to say that the present Brazilian governmental management capability is limited by the lack of disposal data and communication due to the state organization based on federalism and the divisions on civil and military (in this case, navy force) data access, and this had reflections on the profoundity of this study: there L. J. S. TELES & C. H. SAITO were several difficulties to get hands on data, specially maps of water circulation and ships's movement routes. The land use map and the nature conservation unit map (both scaled at 1:250,000) were provided by the Center for Environmental Resources of the State of Bahia (Centro de Recursos Ambientais — CRA). According to this structure, it was determined the areas of exclusion, that is, those considered to be risk areas, where ship unballasting would be neither recommended nor permitted. The criteria used to define the areas of exclusion were based on the potential risks to the environment or to public health resulting from the unballasting. It also could be previously cut out those area where ships cannot circulate by shallow waters where the navigation did not occur. In the present case study, because of the bay format, this previous exclusion was not done and this would not affect the final result, which is to match areas with minimum risks where ballast water exchange could be occur, differently of those area where ships presently discharges ballast water under normal conditions without any environmental concern. Any way, reviewing the methodological procedure, it can be said that in theory, this previous exclusion should be done at first. Finally, a fuzzy logic approach could be applied as an improved assessment to this study and can be a strong suggest for further studies with this same goal, as can be seen in Peche and Rodríguez (2009). Acknowledgements We are grateful to Agência Nacional de Vigilância Sanitária (Anvisa — National Sanitary Vigilance Agency), specially the section responsible for the Salvador port vigilance, for their logistical support to this study. We also wish to thank Ana Lúcia Aragão for her help in creating the maps. References Anvisa. 2003. Projetos GGPAF-2002 (ANVISA. Projects – GGPAF 2002). Brasília, Anvisa, 10 p. (also available at <http://www.anvisa.gov. br/divulga/public/index.htm>). Aronoff, S. 1991. Geographic Information System: A Management Perspective. Otawa, WDL Publ. CRA. Modelamento e Avaliação Ambiental. Relatório de estudos básicos. Salvador, BA. março/2001. 263 p. Elliot, M. 2003. Biological Pollutants and Biological Pollution – An Increasing Cause for Concern. Marine Pollution Bulletin, Hull, UK. vol. 46, Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 Identification of areas for unballasting by geoprocessing - case study in Todos os Santos Bay, Brazil p. 275-280. Goldberg, E. D. 1995. Emerging Problems in the Coastal Zone for the Twenty-first Century. Marine Pollution Bulletin. California, USA, v. 31, n. 4-12, p. 152-158. Hayes, K. R. & Sliwa, C. 2003. Identifying Potential Marine Pests – A Deductive Approach Applied to Australia. Marine Pollution Bulletin, Australia, v. 46, p. 91-98. Malczewski, J. 1999. GIS and Multicriteria Decision Analysis. John Wiley & Sons, Inc. pp392. Pavlovskaya, M. 2006. Theorizing with GIS: a tool for critical geographies? Environment and Planning A, 38:2003-2020. Peche, R.; Rodríguez, E. 2009. Environmental impact assessment procedure: a new approach based on fuzzy logic. Environmental Impact Assessment Review, 29: 275-283. 293 Pollard, D. A. & Hutchings, P. A. 1990. A Review of Exotic Marine Organisms Introduced to the Australian Region. II Invertebrates and Algae. Asian Fisheries Science, Australia, vol. 3, p. 223-250. Thresher, R. E. 1999. Diversity, Impact and Option for Managing Introduced Marine Species in Australian Water. Australia’s Journal of Environmental Management, Australia, v. 6, p. 137-148. Tomlison, R. & Boyle, R. 1971. The State of Development of Systems of Handling Natural Resources Inventory Data. Reprinted from Cartographica, v. 18, n. 4, p. 65-95. Wood, L. J. & Dragicevic, S. 2007. GIS-based multicriteria evaluation and fuzzy sets to priority sites for marine protection. Biodiv. Conserv. 16:2539-2558. Received April 2009 Accepted July 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 283-293 Distribution of planktonic cladocerans (Crustacea: Branchiopoda) of a shallow eutrophic reservoir (Paraná State, Brazil) ANDRÉ RICARDO GHIDINI1; MOACYR SERAFIM-JÚNIOR2; GILMAR PERBICHE-NEVES3 & LINEU DE BRITO4 1 Programa de Pós-Graduação em Biologia Tropical e Recursos Naturais, Instituto Nacional de Pesquisas da Amazônia/Universidade Federal do Amazonas. André Araújo Avenue, nº 2638, Manaus, Amazonas, Brazil. CEP: 69060-001. Email: arghidini@yahoo.com.br. 2 Universidade Federal do Recôncavo da Bahia, Centro de Ciências Agrárias, Ambientais e Biológicas – Núcleo de Estudos em Pesca e Aqüicultura (NEPA), CEP 44380-000, Cruz das Almas, BA. Email: moa.cwb@gmail.com 3 Curso de Pós Graduação em Zoologia, Universidade Estadual Paulista “Júlio de Mesquita Filho” - UNESP, Distrito de Rubião Jr., s/nº, Botucatu, São Paulo, Brazil, CEP: 18618-000. Email: gilmarpneves@yahoo.com.br 4 Universidade Federal do Paraná, Centro de Estudos do Mar, Beira-Mar Avenue, s/no, Pontal do Sul, Paraná, Brazil. CEP: 83255-000. Email:lineubrito@yahoo.com.br Abstract. This study focused the spatial and temporal distribution of the composition, abundance, and diversity of planktonic cladocerans from eutrophic, Iraí Reservoir, as well as their relationships with some biotic and abiotic variables. The tested hypothesis was that cladocerans present higher variation in a temporal than in a spatial scale. The samples were taken monthly in 6 stations, from March/02 to July/03. Twenty-four taxa were identified, distributed in 7 families, the richest families being Daphniidae (6 spp.), Chydoridae (6 spp.), and Bosminidae (5 spp.). The most frequent and abundant species were Bosmina hagmanni, Moina minuta, and Ceriodaphnia cornuta. The highest abundances were found in September/2002. Temporally, rainfall influenced organism’s distribution, while spatially cladocerans were more affected by reservoir hydrodynamics and wind action. The low species richness could be a reflection of the trophic state of the reservoir, in which a dominance of Cyanobacteria was observed during that study period. Both scales showed high variation, but only the temporal scale showed significant difference to richness and abundance. Nearby the end of this study, higher stable values of species richness were recorded, which could suggest an increase in the water quality due to des-pollutions actions. Keywords: Cladocera, Iguaçu River basin, Iraí Reservoir, eutrophication, Cyanobacteria. Resumo. Distribuição de cladóceros planctônicos (Crustacea: Branchiopoda) em um reservatório eutrófico raso (Paraná, Brasil). Esse estudo enfocou a distribuição espacial e temporal da composição, abundância e diversidade de cladóceros planctônicos em um reservatório eutrófico, reservatório do Iraí, bem como suas relações com variáveis bióticas e abióticas. A hipótese testada foi que os cladóceros apresentam maior variação em escala temporal do que espacial. As amostragens foram realizadas mensalmente em seis estações, entre março/02 e julho/03. Vinte e quatro táxons foram identificados, distribuídos em sete famílias, sendo Daphniidae (6 spp.), Chydoridae (6 spp.) e Bosminidae (5 spp.) as que ativeram maior número de espécies registradas. As espécies mais freqüentes e abundantes foram Bosmina hagmanni, Moina minuta e Ceriodaphnia cornuta. A maior abundância foi registrada em setembro/02. Temporalmente a pluviosidade influenciou a distribuição dos organismos, enquanto espacialmente os cladóceros foram mais afetados pela hidrodinâmica do reservatório e pela ação do vento. A baixa riqueza de espécies pode ser um reflexo do estado trófico do reservatório, no qual a dominância de Cyanobacteria foi observada quase que constantemente. Ambas as escalas apresentaram elevadas variações, porém somente a temporal apresentou diferença significativa para a riqueza e abundância. Próximo do final deste estudo, maiores valores estáveis de riqueza de espécies foram verificados, a qual pode sugerir uma melhoria na qualidade de água devido a ações de despoluição. Palavras-chave: Cladocera, rio Iguaçu, reservatório do Irai, eutrofização, Cyanobacteria. Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 Distribution of planktonic cladocerans of a shallow eutrophic reservoir Introduction The importance of continental aquatic ecosystems as a source of freshwater to human populations is unquestionable. However, anthropogenic activities have been degrading these environments and the water quality, altering its physical, chemical, and biological properties, a phenomenon called eutrophication (Bollmann & Andreoli 2005). Changes in the nutrients dynamics of a water body alter the decomposition and production processes that directly affect the consumption. This fact can be evidenced studying planktonic microcrustaceans since its life cycle, development, and reproduction are influenced by biotic and abiotic factors of the environment (Branco & Cavalcanti 1999, Bini et al. 2008). In tropical environments, rain and wind action are the major forces influencing cladocerans population structure, promoting the water column mixing, and stimulating nutrient cycling (Lopes et al. 1997, Sampaio et al. 2002). Factors as pH, dissolved oxygen, and nutrients (especially P and N) directly affect these organisms, because they strongly influence phytoplankton development (Bonecker et al. 2001, Matsumura-Tundisi & Tundisi 2003, 2005). Furthermore, cladocerans populations can oscillate in response to predation by other groups, like insect’s larvae and small fishes (Meschiatti & Arcifa 2002). Most cladocerans are herbivorous and phytoplankton feeders, transferring energy to higher trophic levels (Melão 1999). This is the reason why generalist’s cladocerans species are able to develop in a high number of environments, like species of the Bosminidae family. Some large cladocerans (Sididae and Daphniidae families) have preference on the food item ingested, and they became more selective when there is food limitation (DeMott & Kerfoot 1982, Ferrão-Filho et al. 2003). Filamentous algae and presence of toxins affect cladocerans growth and filtering rates, besides to increase mortality and polymorphism, which in a spatialtemporal scale influences the composition, distribution and species succession (Ferrão-Filho & Azevedo 2003). This is particularly important in eutrophic reservoirs where food availability from cladocerans changes with time since cyanobacteria blooms, which occur during almost the whole annual cycle, can develop toxicity (Ferrão-Filho et al. 2003). Temporal-spatial variations of microcrustaceans in Brazilian reservoirs have been extensively studied (Bonecker et al. 2001, Sampaio et al. 2002, Matsumura-Tundisi & Tundisi 2003, 295 2005, Corgosinho & Pinto-Coelho 2006). However, in small and eutrophic reservoirs, as the case of Iraí Reservoir and which is the aim of this study, the relationships between cladocerans assemblages and limnological factors (biotic and abiotic) are poorly known besides they can affect population structure. Lansac-Tôha et al. (2005), Velho et al. (2005), Serafim-Júnior et al. (2005) and Perbiche-Neves et al. (2007) studied this reservoir and attributed the homogeneity of zooplanktonic assemblages to the low depth, long residence time and elevated production, with the dominance of cyanobacteria. Pinto-Coelho et al. (1999) made similar observations to Pampulha Reservoir (MG), which is small, eutrophic and located in a region of strong urbanization. In small, shallow and polymictic reservoirs, Henry (1999) highlighted the wind action effects on the water column, where daily or temporary stratifications can occur, but they are subjected to the vertical homogenization in most part of the year. The comprehension of the relationship between cladocerans assemblages and environmental conditions are important to the development of ecological tools used in management techniques and environmental restoration of eutrophic reservoirs. Also, the knowledge of those relations could be useful to understand Cladocera ecology in sub-tropical reservoirs, nevertheless used to water supply to the city of Curitiba and metropolitan region, composed of ca. 3.5 million habitants. The hypothesis tested in this study was that cladocerans variation occurs mainly in a temporal than in a spatial scale, associated to the small size of the reservoir, being a homogeneous assemblage, due the its relation to some limnological variables and specially to phytoplankton community, because their food item selectivity. The aim of this work was to describe: (i) the temporal-spatial distribution of some ecological attributes of cladocerans populations and the major limnological variables influencing them; (ii) the intensity of eutrophication that affect these organisms, and (iii) the relation between cladocerans and the phytoplankton community. Material and Methods Study area. The Iraí Reservoir (25º 25’49’’S and 49º 06’40’’W) is located in the basin of higher Iguaçu River among the cities of Pinhais, Piraquara, and Quatro Barras. It occupies an area of 14 km2 in the alluvial plain of Iraí River. The mean water volume is 58x106 m-3, the theoretical residence time is 300 to 450 days, and the mean depth is 4 m. (Zmax=10 m). The margins are not vegetated, being Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 296 A. R. GHIDINI ET AL. composed mainly by pastureland (Andreoli & Carneiro 2005). Iraí Reservoir was built in 2001 and its morphometrical and hydrological features have been causing Cyanobacteria proliferation since its filling, complicating water treatment and reducing water quality (Andreoli & Carneiro 2005). One of the four main tributaries (Timbú River) is characterized by an elevated nutrient load, especially of phosphorus and nitrogen, due to the disordered urban occupation of the drainage basin. This fact, associated to the high residence time and low dept of the reservoir favored the development of blooms of Cyanobacteria, as Anabaena sp., Cylindrospermopsis sp., and Microcystis sp., promoting significantly changes in the water quality of the reservoir (Bollmann & Andreoli 2005). Field work, samples and data analyses. The samples were obtained monthly from March/2002 to July/2003 in six stations in the reservoir, totalizing 102 samples. Stations 1, 2 and 3 were located in the dam axis (stations 1 and 3, Zmax= 4 m; station 2, Zmax= 8 m), and the others were in the main body the reservoir (stations 4, 5, and 6, Zmax= 3 m) (Fig. 1). Two-hundred liters of sub surface water (due to low depth) were filtered in a conical plankton net (55 µm mesh size), using a motorized pump. The samples were narcotized with 4 % buffered formalin. Countings were made through subsamples of 1 mL using Stempel pipette, and a minimum of 200 individuals were counted per sample in a Sedgewick-Rafter chamber under optical microscope. Cladocerans are usually quantified in acrylic gridded Petri dishes using stereomicroscope. However, in this study, countings in SedgewickRafter were possible due to the elevate number of small organisms. Identification of species was based in specialized literature, as Matsumura-Tundisi (1984), Elmoor-Loureiro (1998; 2007), Hollwedel et al. (2003) and Elmoor-Loureiro et al. (2004). Abundance data were expressed as individuals.m-3. Figure 1. Localization of Iraí Reservoir (Paraná State) and of sampling stations Non-parametric tests were used after Shapiro-Wilk normality test have indicated a not normal distribution. Organism’s richness and abundance were analyzed using H Kruskal-Wallis ANOVA test (p < 0.05) to detect significant variations between sampling stations and months. Biotic and abiotic variables for limnological characterization were not different among the stations (p > 0.05). It was used data of station 2, in middle dam zone. Biotic and abiotic variables were related to the cladocerans abundance. Phytoplankton species abundance and cladocerans abundance interactions were analyzed using the Spearman correlation (p < 0.05). Due to the elevate number of statistical analyses applied, multiple comparisons tests between the means of analyzed categories were used to avoid error type I on null hypothesis. Multiple comparisons analyses of “p” values (Z, p > 0.05) were performed on the significance tests of H Kruskal-Wallis ANOVA and Bonferroni correction (β, p > 0.05) on Spearman correlations. Despite the corrections, infringements about null hypothesis Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 297 Distribution of planktonic cladocerans of a shallow eutrophic reservoir were not significant. Biotic and abiotic variables were correlated with Cladocera using Factorial Analysis (p < 0.05) with extraction by Principal Component Analysis. Mantel test with 1000 permutations for dissimilarity matrices between cladocerans data versus phytoplankton data (also with Bray Curtis distances) versus abiotic data (with Euclidian distances) was performed, but a significant correlation was not obtained. Factorial Analysis was performed using Statistic 6.0 software (Statsoft 2002), and the other analyses were carried out using “R Development Core Team” (2009). Data of abundance, composition and phytoplankton biomass, and water physical-chemical parameters (chlorophyll-a, pH, temperature, dissolved oxygen, electric conductivity, turbidity, organic nitrogen and total phosphorus) were obtained in same stations and months through the data base of "Projeto multidisciplinar de pesquisa em eutrofização de águas de abastecimento público”. For further details of sampling methodologies and analyses, as well as the responsible authors, see Andreoli & Carneiro (2005). Monthly mean pluviosity was obtained from data base of Technological Institute SIMEPAR. Results Species richness (S) values varied significantly during the studied months (H=71.23, p < 0.00), with lower mean value in March/2002 (S = 4.2), and higher mean value in December/2002 (S = 12) and November/2002 (S = 11.5). From November/2002 to February/2003 (rainy season), the highest means, maximum values and variation (standard deviation and min/max) in species richness were observed among the stations (Table I). After this, richness tended to stability from July (S: 7.510; mean: 8.7). Significant spatial variation of richness was not observed (H = 1.59, p = 0.97, Z = p > 0.05). Table I. Cladocerans richness species (Mean, Standard deviation - SD and Minimum/Maximum - Min/Max) at Iraí Reservoir from March/2002 and July/2003 (N = 102). 2002 Mean SD Min/Max 2003 Mean SD Min/Max Mar 4.2 ±1.17 3-6 Jan 10.8 ±2.64 8-15 Apr 6.0 ±1.26 4-8 Feb 9.5 ±1.64 7-12 May 5.5 ±1.52 4-8 Mar 7.5 ±1.05 6-9 Jun 6.7 ±0.82 6-8 Apr 8.3 ±2.16 5-11 Jul 6.5 ±1.38 6-8 May 9.3 ±1.63 9-12 Aug 6.3 ±1.63 4-9 Jun 10.0 ±0.63 9-11 Sep 7.7 ±1.51 6-10 Jul 7.7 ±2.07 8-11 Oct 8.8 ±1.47 7-11 Nov 11.5 ±1.87 9-14 Dec 12.0 ±1.79 9-13 A total of 24 species was identified (Table II). The most frequent cladocerans species in the samples were Bosmina hagmanni (94%), followed by Moina minuta (84%), Ceriodaphnia cornuta (70%), Bosmina longirostris (67%), and Ceriodaphnia silvestrii (64%). Bosmina hagmanni was also the most abundant species during the whole study period (relative abundance = 65 %). Chydoridae and Daphniidae families presented higher richness (six species), and the last family was the most abundant. Five Bosminidae species were recorded (Table II). In a temporal scale, a significant difference in cladoceran abundance was observed along the studied months (p < 0.00, H = 70.68), but with no distinguished pattern of variation. Lower abundances were found in March/2002 and 2003, and in June and July/2003. A peak of abundance was observed in September/2002, and to the following months, elevated densities were observed until January/2003. In May/2003 values also increased (Fig. 2). Most cladocerans species, mainly the more abundant, followed the variation showed in Figure 2. The variation was especially evident to smaller cladocerans, as B. hagmanni responsible for the density peak during September/2002, when densities were more than 12 fold higher compared to previous Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 298 A. R. GHIDINI ET AL. months (≈ 600,000 org.m-3). In October/2002, abundance of that species decreased progressively until its absence in March and April/2003. Moina minuta higher densities were found in May/2002 (≈ 55,000 org.m-3), and population declined in August and September/2002. A peak of Ceriodaphnia cornuta was observed in October/2002 (≈ 60,000 org.m-3). Table II. Recorded species at Iraí Reservoir, relative abundances (Ab %), and frequency of occurrence (Fr %) in the samples, from March/2002 to July/2004. Taxa Ab% Fr% Taxa Ab% Fr% Bosmina hagmanni Stingelin, 1904 65.4 94.1 Ilyocryptus spinifer Herrick, 1882 <0.1 3.3 Bosmina huaronensis Delachaux, 1918 2.3 40.3 Macrothricidae Bosmina longirostris Müller, 1785 4.8 58.8 Macrothrix squamosa Sars, 1901 <0.1 0.8 Bosmina tubicen Brehm, 1953 <0.1 2.5 Moinidae Bosminopsis deitersi Richard, 1895 1.5 40.3 Moina micrura Kurz, 1874 <0.1 3.3 Moina minuta Hansen, 1899 6.6 84.0 10.0 Moinodaphnia macleayi King, 1853 <0.1 0.8 Bosminidae Ilyocryptidae Chydoridae Alona guttata Sars, 1862 <0.1 Alona intermedia Sars, 1862 <0.1 2.5 Sididae Alona monocantha Sars, 1901 0.1 15.1 Diaphanossoma birgei Korineck 1981 0.4 35.2 Alonella dadayi Birge, 1910 <0.1 3.4 Diaphanossoma brevireme Sars 1901 0.1 11.7 Chydorus eurynotus Sars, 1901 1.3 37.8 Diaphanossoma spinulosum Herbst, 1967 0.1 11.7 Chydorus nitidulus Sars, 1901 0.2 11.7 Ceriodaphnia cornuta Sars, 1886 5.0 73.1 Ceriodaphnia cf. laticaudata Müller, 1867 0.6 24.3 Ceriodaphnia reticulata Jurine, 1820 2.7 43.7 Ceriodaphnia silvestrii Daday, 1902 3.7 72.2 Daphnia gessneri Herbst, 1967 <0.1 8.4 Daphniidae Considering larger cladocerans (> 1.00 mm), their densities were less representative compared to smaller species. Diaphanosoma birgei reached a peak in November/2002 (≈ 2,000 org.m-3) and was always recorded since then. This species was absent in the previous samples (June, August, and September/2002). Daphnia gessneri was not found in the first months, appearing in the samples in October/2002, with increasing populations densities in the following months. Figure 2. Cladocerans mean densities (individuals.m-3 x103) from March/2002 to July/2003, at Iraí Reservoir (N=102). Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 Distribution of planktonic cladocerans of a shallow eutrophic reservoir Inside Iraí Reservoir, B. hagmanni population densities were, generally, slightly higher in stations 1 and 3, located in the left and right margins of the dam, while C. cornuta was more abundant at station 5, followed by stations 1 and 3. Some larger species, like D. birgei, presented elevated maximum abundances in stations 4 and 5, and D. gessneri in station 6 (Fig. 3). It was not detected any significant difference between total and species abundance among sampling stations 299 (H = 4.54, p = 0.60, Z = p > 0.05). Significative Spearman correlation (R) between dominant cladocerans abundance and phytoplankton densities showed positive correlation with two Ceriodaphnia and two Chydoridae species with densities of Microcystis aeruginosa, one of the most abundant Cyanobacteria present in the reservoir in this study. There were no positive correlations between cladocerans and the other algae genera (β = p > 0.05) (Table III). Figure 3. Spatial distribution of some cladocerans species inside Iraí Reservoir. Dark paths represent higher mean abundances from March/2002 to July/2003. For localization of stations sampling, see Figure 1. Table III. Significative Spearman correlations between cladocerans and phytoplankton considering the mean population density during the studied period (p<0.05). Aual- Aulacoseira alpigena, Miae- Microcystis aeruginosa, Momi- Monoraphidium minutum, Peum- Peridinium umbonatum, Scen- Scenedesmus sp., TetrTetraedon sp, Uros- Urosolenia sp. Aual Miae Momi Peum Scen Tetr Uros 0.72 -0.63 -0.72 C. cornuta -0.63 -0.69 C. reticulata 0.73 -0.76 -0.64 C. silvestrii 0.73 -0.79 -0.67 C. eurynotus 0.79 -0.69 -0.71 -0.72 C. nitidilus -0.79 -0.77 -0.66 D. gessneri -0.79 D. birgei -0.75 D. brevireme Spearman correlations were not significant (p < 0.05) among environmental variables (dissolved oxygen, pH, electric conductivity, total phosphorus, organic nitrogen, water transparency, and chlorophyll-a) and cladocerans population densities (β = p > 0.05). Results from Factor Analysis (Factor 1: 31.59%, Factor 2: 22.10%) indicated a close relation between cladoceran abundance and mean pluviosity (Fig. 4). Slightly correlation among Cladocera with phytoplankton and turbidity in the second factor were observed. The pluviometric means at Iraí Reservoir region showed an increase in rainfall episodes in September/2002, indicating the beginning of rainy period (Fig. 5). In the same month, the peak of B. hagmanni density was observed in station 2, calling attention a peak in phytoplankton abundance one month before (August/2002). In dry period of 2002 (May from August) were recorded a decrease in the pluviometric indexes, as to April to June of 2003, when cladocerans abundances were also low, except in May/2003. Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 300 A. R. GHIDINI ET AL. Figure 4. 2D loadings for factors 1 and 2 of the Factor Analysis of station 2. ac: a-chlorophyll; Clad: cladocerans total density; Cond: electrical conductivity; O: dissolved oxygen; OrgN: organic nitrogen; Phyto: phytoplankton’s species richness; TotP: total phosphorus; Rain: mean rainfall for each month; Transp: Secchi’s transparency; Turb: turbidity; Tw: water temperature. Figure 5. Mean pluviosity, total Cladocera and phytoplankton abundance in station 2 between June/2003. Discussion Most species recorded in this study are commonly found in the basin of Paraná River, especially the dominant planktonic, as B. hagmanni, M. minuta, and C. cornuta (Nogueira et al., 2008). These species were also found in other aquatic Brazilian environments (Robertson & Hardy 1984, Santos-Wisniewski et al. 2000). In general, Bosminidae, Moinidae, and Daphniidae families are dominant in lenthic aquatic ecosystems like reservoirs as verified by Sampaio et al. (2002). Lansac-Tôha et al. (2005) also found the dominance of these families at Iraí Reservoir. Representants of Macrothricidae and April/2002 and Ilyocryptidae families were less common in this study. They living in the littoral zone or nearby (Serafim-Júnior et al. 2003), and their presence in limnetic zone is accidental. The same consideration can be done to the Chydoridae family, but C. eurynotus and C. nitidilus were found in relatively high abundances compared to the other species of this family. Records of Chydoridae in the limnetic zone were found by Paggi & José de Paggi (1990) that considered some Alona species as pseudoplanktonic since its abundance was higher in the limnetic zone compared to the littoral zone of river channel and floodplain lakes. Cladocerans are affected by several factors Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 Distribution of planktonic cladocerans of a shallow eutrophic reservoir at Iraí Reservoir, mainly due to its shallowness, presenting a large superficial area as shown in Figure 1. In the beginning of the rainy season, increased nutrients availability to the water column allowed their incorporation by the aquatic communities (Nogueira et al. 2008, Serafim-Júnior et al. 2005). The low depth and the geomorphology of the reservoir induce organic matter and nutrients accumulation, and consequently, phytoplankton presence in areas next to the margins, favoring the development of small cladocerans. Larger species, however, are distributed in areas far from the dam. The great amplitude variation of species richness in the rainy season can be related to two factors. First, the spatial heterogeneity of cladocerans, which explore the environment in different ways (Pinel-Alloul 1995), searching for adequate conditions for their development, for example, when an increase in altimetric quote and volume of the reservoir raises food availability and alter the phytoplankton community. Second, rain effect is noticeable because it causes the transport of autochthonous (from littoral zone) and allochtonous materials (from tributaries and other smaller lakes in the same basins). Lansac-Tôha et al. (2005) found slightly higher cladocerans richness at Iraí Reservoir during the rainy period. Generally, there was an increase in cladocerans species richness during this study, possibly reflecting the processes of colonization and stabilization of the water column, a fact also observed in other reservoirs (Esteves & Camargo 1983). A trend of cladoceran temporal variation was observed after November/2002, when a richness peak was observed, followed by stable values, with a mean of 8.7 species. In contrast, in the same period, considering other plankton communities, Fernandes et al. (2005) did not find a pattern of species richness variation and abundance of the phytoplankton in Iraí Reservoir, as well as PerbicheNeves et al. (2007) studying copepods. Also despollution actions were made in Iraí drainage basin and it can reflect in better quality water conditions. Elmoor-Loureiro et al. (2004) verified similar conditions in Paranoá Reservoir (Brazil), with new cladoceran records after a long period of water quality treatment of this reservoir. Spatial variation of the most limnological features of the reservoir was very similar and homogeneous (Andreoli & Carneiro 2005), except by the concentration of nitrogenates and phosphates forms due to the tributaries rivers. Except the nutrients, homogeneous conditions can be associated to the constant cladocerans species numbers among sampling stations, probably related to the carrying 301 capacity of the reservoir. Begon (2007) comments about this for ecological communities in general. Generally, in small and shallow reservoirs, two important parameters that promote water column mixing in reservoirs are the tributaries water velocity and wind dynamics. At Iraí Reservoir, wind effect is very important because its action on water surface causes accumulation of nutrients and algae in areas next to the dam (Gobbi et al. 2005), also influencing, as an example, the phytoplankton community (Fernandes et al. 2005) and the spatial distribution of copepods (Perbiche-Neves et al. 2007). Wind can also affect cladocerans spatial distribution, but a significant difference was not detected in the total abundance of cladocerans assemblages, as well as of species richness in this study. Considering cladoceran temporal abundance peaks, was noticed the dominance of small organisms, especially B. hagmanni. In contrast, Elmoor-Loureiro (1988) states that to B. longirostris, B. hagmanni have never been associated to eutrophic environments and that elevated densities of these species were found in lakes with low nutrients. Thus, B. hagmanni dominance can be related with other variables not favorable to the dominance of B. longirostris, but detailed studies, as laboratory bioassays must be carried out to evaluate this relations. Dominance of small cladocerans like bosminids in eutrophic reservoirs was also found in other Brazilian studies (Branco & Cavalcanti 1999, Pinto-Coelho et al., 1999, Sendacz et al., 2006). It can be suggested that the dominance of B. hagmanni was favored by the eutrophication of Irai Reservoir, because this species corresponded to more than half of the total relative abundance. On the other hand, other species of the Daphniidae, Sididae, and Moinidae families were dominant in oligo/mesotrophic environments like some reservoirs of high Paranapanema River (Nogueira et al., 2008). Although not so abundant as B. hagmanni, M. minuta and C. cornuta elevated abundances can be explained by the adaptation of these species to food resources. They fed not only on phytoplankton, but also on detritus and bacteria (DeMott & Kerfoot 1982, Dole-Olivier et al. 2000). Furthermore, they have a fast development, associated to the high water temperature in the rainy season and to the great offer of food during the whole year at Iraí Reservoir, represented by Cyanobacteria. According to Monakov (2003), predation of cladocerans on bacterioplankton is one of the reasons of the development success of these organisms in adverse conditions. Success of this species was verified in Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 302 many reservoirs in Paranapanema River (Brazil) (Nogueira et al., 2008). Generally, large cladocerans abundance is low when compared to small cladocerans, however, their biomass is high, balancing the contribution of these organisms to the community (Sendacz et al., 2006; Corgosinho & Pinto-Coelho, 2006). Studies indicate that large cladocerans fed on algae, few species are detritivorous, and most species are selective to food quality (DeMott & Kerfoot 1982, de Bernardi et al. 1987). Other studies show that herbivory on large phytoplankton, as large colonies of Cyanobacteria by zooplanktonic filter feeders is difficult and energetically poor, especially if it involves algae toxicity (Ferrão-Filho & Azevedo 2003). Considering Ceriodaphnia cornuta, a dominant cladoceran in this study, the explanation of the high correlation with M. aeruginosa could be the great niche variety that this species could occupy, feeding, in this case, on Cyanobacteria early associated with cyanotoxins in Iraí Reservoir (Fernandes et al. 2005). Ferrão-Filho & Azevedo (2003) found that feeding on colonial (Microcystis) and filamentous algae is difficult to small cladocerans and that they feed mainly on individual or in decomposition cells. Apparently, only large cladocerans, as Daphnia, are able to feed on individual cells or colonies of Microcystis (Rohrlack et al. 1999, Nandini 2000). Kobayashi et al. (1998) also state that large cladocerans are able to feed efficiently on large Microcystis colonies and that this can be influenced not only by alga toxicity, but also by colony disaggregation. The same was observed in Trabeau et al. (2004) experiments, that rising alga biovolume and microcystin production observed a decline of Daphnia populations, associated to an increase in energetic costs of feeding. Conversely, AlvaMartinez et al. (2001) detected an increase of population growth of one species of Daphnia and one of Ceriodaphnia when fed with increasing concentrations of Microcystis aeruginosa. Similar results could be expected in Iraí Reservoir, but laboratory bioassays are needed to test the influence of food on cladocerans populations. Other phytoplankton species demonstrated negative correlation with cladocerans, as D. gessneri, that showed a negative correlation with A. alpigena, M. minutum, and Tetraedon sp. Lampert (1987) states that Daphnia feeding apparatus is specialized to feed on nanoplankton (5-60µm, according to Hutchinson 1967), and that ingested algae species can vary with the animal body size. Considering the three cited algae species, they are too large to be consumed by D. gessneri, explaining A. R. GHIDINI ET AL. the negative correlation found in this study. Diaphanosoma birgei and D. brevireme showed a negative correlation with the diatomacean Urosolenia sp. Despite baccilariophyceans are considered an indispensable food item to cladocerans that feed on periphyton, they are not commonly ingested by planktonic cladocerans (Nogueira et al. 2003). In the other hand, for copepods, Perbiche-Neves et al. (2007) found a high positive correlation with the diatomaceans during the same period of the present study at Iraí Reservoir. After B. hagmanni peak in September/2002 there was a subsequent decline of Bosmina population’s densities, when Microcystis aeruginosa cells densities was higher within chlorophyll-levels until January/2003. This decline could be related to the difficult of cladocerans in feeding on Cyanobacteria colonies, or due to the toxicity of the alga. The fact that M. aeruginosa and cladocerans densities decreased in October/2002 and that cladoceran species richness raised after October can indicate an increase in the food offered to cladocerans. M. aeruginosa blooms can also be associated with the population increase or appearance of the larger cladocerans Daphnia and Diaphanosoma in the lake that could be favored by the development of this alga. Pinel-Alloul et al. (1988), studying the spatial distribution of zooplankton suggests that developmental stage, body size, and periodicity are factors that can influence data obtainment of population density horizontal variation and zooplankton species richness. However, tropical lakes are generally small, shallow, and it is difficult to establish a large scale of spatial heterogeneity (Rocha et al. 1995, Sarma et al. 2005). In these cases, density and species richness spatial variation can only be determined when adjacent regions of lenthic zones are included in the sampling program. Areas next to the margins, where detritus and cyanobacterians accumulate due the low water flux and wind direction, favor the development of small cladocerans, while larger species find better habitat conditions and greater food diversity in areas far from the dam. Through the studied months, elevated rain episodes promoted water column mixing, occasioning slightly relation with turbidity in factor analysis, returning nutrients and organic matter to the water column, causing the abundance peak of B. hagmanni in September/2002. The water column mixing increased the nutrients availability to the primary producers, and, in this case, high abundance of cyanobacterians favored the appearance and Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 Distribution of planktonic cladocerans of a shallow eutrophic reservoir development of larger cladocerans. This can also be associated to an increase of the food quantity and quality available, promoting the development of more species, explaining the elevated cladoceran species richness during the summer of 2002 and 2003 years. But in the absence of higher pluviosity, it was also verified a peak of phytoplankton abundance, like in August/02, represented by strategic cyanobacterians that can development in such conditions. Both spatial and temporal variations were relevant but the first was not significant, rejecting in part the hypothesis that the temporal variation was more probable. Spatial variation was influenced mainly by morphometrical characteristics of the reservoir, and temporal variation by climatic changes in the sampling period, especially pluviosity and water temperature, very contrasting events in sub-tropical regions. Seasonal and temporal variation of species richness and population densities described in this study probably is due to alterations in the hydrological and biological characteristics of the reservoir. 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Received April 2009 Accepted July 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 294-305 First report of larval Spiroxys sp. (Nematoda, Gnathostomatidae) in three species of carnivorous fish from Três Marias Reservoir, São Francisco River, Brazil MICHELLE D. SANTOS1, MÁRCIA C. ALBUQUERQUE1, CASSANDRA M. MONTEIRO1, AMANDA N. MARTINS1, NICOLE B. EDERLI1, MARILIA C. BRASIL-SATO2 1 Curso de Pós-Graduação em Ciências Veterinárias, Universidade Federal Rural do Rio de Janeiro, RJ, Brasil. Email: michelledaniele@yahoo.com.br 2 Departamento de Biologia Animal, Universidade Federal Rural do Rio de Janeiro, Caixa Postal 74.539, 23851970, Seropédica, RJ, Brasil. Abstract. The objective of this paper was to evaluate the parasitism by nematode larvae at three species of carnivorous fish in the Três Marias Reservoir, Brazil. It was verified 108 individuals of Pygocentrus piraya (Cuvier, 1819), 168 Serrasalmus brandtii Lütken, 1875, and 112 Cichla kelberi Kullander & Ferreira, 2006. A total of 59 individuals of nematode larvae were found in the three hosts and identified as third stage (L 3 or infective larvae of definitive host) Spiroxys sp.. The parasitic indexes were more elevated in the P. piraya and S. brandtii, although the prevalence and abundance of Spiroxys sp. were higher in smaller specimens of S. brandtii. This may be explained since these juveniles feed some arthropods, that serve as intermediate hosts and fish parasitized by larvae of Spiroxys sp. while foraging. Just two individuals of C. kelberi were parasitized by Spiroxys sp. and this rare occurrence was shown to be accidental. This record adds to the current knowledge of this nematode’s life cycle and provides evidence that these carnivorous fish serve as paratenic hosts of Spiroxys sp. larvae in that Reservoir. Key words: Pygocentrus piraya, Serrasalmus brandtii, Cichla kelberi, paratenic host fish. Resumo: Primeiro registro de larvas de Spiroxys sp. (Nematoda, Gnathostomatidae) em três espécies de peixes carnívoros do Reservatório de Três Marias, Rio São Francisco, Brasil. O objetivo deste trabalho foi avaliar o parasitismo de larvas de nematóides em três espécies de peixes carnívoros no Reservatório de Três Marias, Minas Gerais. Foram examinados 108 indivíduos de Pygocentrus piraya (Cuvier, 1819), 168 de Serrasalmus brandtii Lütken, 1875 e 112 de Cichla kelberi Kullander & Ferreira, 2006. Um total de 59 indivíduos de nematóides larvais encontrados nas três espécies de hospedeiros foram identificadas como Spiroxys sp., no terceiro estágio (L3 – larva infectante ao hospedeiro definitivo), cujos índices parasitários foram mais elevados em P. piraya e S. brandtii. Contudo, a prevalência e a abundância de Spiroxys sp. foram mais elevadas em espécimes menores de S. brandtii, pois os juvenis desta espécie se alimentam de artrópodes (com hospedeiros intermediários) e peixes parasitados pelas larvas de Spiroxys sp.. Apenas dois indivíduos de C. kelberi hospedaram larvas de Spiroxys sp. o que pode ter sido acidental. Os resultados encontrados neste trabalho associados ao conhecimento do ciclo de vida dos nematóides evidenciam que estes peixes carnívoros atuam como hospedeiros paratênicos das larvas de Spiroxys sp. no Reservatório de Três Marias. Palavras-chave: Pygocentrus piraya, Serrasalmus brandtii, Cichla kelberi, hospedeiros paratênicos Introduction Três Marias Reservoir is located on the Upper São Francisco River, São Francisco River Basin, in the central region of the State of Minas Pan-American Journal of Aquatic Sciences (2009), 4(3): 306-311 First report of larval Spiroxys sp. in fishes from Três Marias Reservoir, Brazil Gerais, Brazil. It was inundated in 1961 and at its maximum level has a surface area of roughly 100 thousand hectares and volume of 21 billion cubic meters (Britski et al. 1988). It is important to regulate the level of water in the River San Francisco for navigation, control of floods, irrigation and electric power production (Sampaio & López, 2003). The endemic serrasalmines Pygocentrus piraya (Cuvier, 1819) and Serrasalmus brandtii Lütken, 1875 and the allochtonous cichlid Cichla kelberi Kullander & Ferreira, 2006, are important fishes in fisheries along the São Francisco River. Pygocentrus piraya is commonly known as “piranha”. It can reach a total length of 51 cm (Pinkguni 1997) and weigh over 6 kg (Ferreira et al. 1996). It is carnivorous, preferentially feeding on other fish (Britski et al. 1988, Alvim 1999), behaves opportunistically (Gomes 2002) and gregariously and generally inhabits lentic environments (Braga 1975). It is abundant in the Três Marias Reservoir (Britski et al. 1988). Serrasalmus brandtii is commonly known as “pirambeba” or “white piranha” (Jegú 2003), and can reach a total length of 31 cm and weight of 700 g (Braga 1975). According to Gomes & Verani (2003), S. brandtii is generally smaller than P. piraya. It is also carnivorous, preferentially feeding on other fish (Alvim 1999, Gomes 2002) and can tear pieces from its prey with its sharp cutting teeth (Britski et al. 1988). Alvim (1999) concluded that S. brandtii is a piscivore that feeds mainly on the fins of smaller fish. Pompeu & Godinho (2003) classify S. brandtii as a piscivoreinsectivore species. Cichla kelberi, known commonly as “tucunaré” is a species originally from the Tocantins River Basin (Kullander & Ferreira 2006) that lives in lentic environments where it reproduces mainly during the rainy season (Zaret 1980). Tucunarés have been caught by professional fishermen in Três Marias Reservoir since 1982, but it is not known how the species was introduced (Magalhães et al. 1996). Moreira (1994) reported Procamallanus (Spirocamallanus) inopinatus Travassos, Artigas & Pereira, 1928 in P. piraya from the Três Marias Reservoir. Moravec et al. (2008) redescribed and reported Cystidicoloides fischeri (Travassos, Artigas & Pereira, 1928) in P. piraya and S. brandtii from the same locality. Santos (2008) found Spinitectus rodolphiheringi Vaz & Pereira, 1934 in P. piraya., Philometra sp. in S. brandtii., Rhabdochona sp. in C. kelberi, as well as Hysterothylacium sp., Goezia. sp. and Capillostrongyloides sp. from these carnivorous hosts. This work constitutes the first about the 307 various parasitological studies of the carnivorous fish from the Três Marias Reservoir. The aim of this study was to evaluate the ecological-parasite descriptors of the nematode larvae (prevalence, intensity and mean abundance) with the biotic aspects of the hosts (sex and total length), feeding behavior and collection period (dry and wet period) of these important carnivorous fish from the Três Marias Reservoir. Materials and Methods The collection of hosts was as follows: 108 specimens of P. piraya were caught between July and August, 2004 (dry season) and December, 2004 and January, 2005 (wet season); 168 specimens of S. brandtii were caught between July to August, 2004 and July, 2005 (dry season) and January, 2004 and January, 2005 (wet season); and 112 specimens of C. kelberi were collected between August, 2004 and July to August, 2005 (dry season) and between December to January, 2004 and January, 2005 (wet season). The fishes were collected in the Três Marias Reservoir, in the area of influence of the Borrachudo River (18º12'59"S, 45º17'34"W), Upper São Francisco River, in the municipality of Três Marias, State of Minas Gerais, Brazil by fishermen from the Estação de Hidrobiologia e Piscicultura of the Companhia de Desenvolvimento dos Vales do São Francisco e do Parnaíba (EPT/CODEVASF). The specimens of P. piraya and S. brandtii were identified and classified according to Britski et al. (1988) and Jegú (2003), while the specimens of C. kelberi according to Kullander & Ferreira (2006). The nominal taxa of fish followed FishBase (Froese & Pauly 2007). The larval specimens of Nematoda were collected, fixed and processed according to Amato et al. (1991) and identified and classified according to Moravec (1998). The ecological descriptors utilized in the parasitological results followed Bush et al. (1997). The statistical tests were only applied for the larval nematodes of fish species with prevalence of 10% or higher, following the recommendation of Bush et al. (1990). All the statistical analyses applied to the infrapopulations followed Zar (1996), at a significance level of p<0.05. Voucher specimens of P. piraya, S. brandtii and C. kelberi, were deposited in the Museu de Zoologia of the Universidade de São Paulo, São Paulo, Brazil (MZUSP: 95150, 95148 and 95149). Voucher specimens of nematode larvae from the three hosts were deposited in the Coleção Helmintológica do Instituto Oswaldo Cruz (CHIOC: 36959, 35557, 36953, respectively), Rio de Janeiro, Brazil. Pan-American Journal of Aquatic Sciences (2009), 4(3): 306-311 308 Results and Discussion Of the 108 specimens of P. piraya collected, 56 were males with average total length of 18.1 ± 4.4 cm (11.1 to 30.5 cm) and average weight of 169.8 ± 180.1 g (21.0 to 835.0 g), and 52 were females with average total length of 21.4 ± 6.0 cm (13.0 to 34.0 cm) and average weight of 323.4 ± 308.4 g (40.0 to 1225.0 g). Of the 168 specimens of S. brandtii collected, 55 were males with average total length of 16.2 ± 3.5 cm (9.5 to 27.0 cm) and average weight of 96.9 ± 96.4 g (11.0 to 500.0 g), and 113 were females with average total length of 16.9 ± 4.6 cm (8.5 to 29.5 cm) and average weight of 125.5 ± 142.9 g (7.0 to 657.0 g). Of the 112 M. D. SANTOS ET AL. specimens of C. kelberi collected, 59 were males with average total length of 29.6 ± 6.2 cm (18.0 to 48.0 cm) and average weight of 419.2 ± 285.3 g (85.0 to 1540.0 g), and 53 were females with average total length of 28.4 ± 4.4 cm (20.0 to 35.5 cm) and average weight of 366.9 ± 179.7 g (85.0 to 684.0 g). A total of 59 specimens (27 in P. piraya, 30 in S. brandtii and two in C. kelberi) of nematode larvae found in the three hosts were identified as third stage (L3) Spiroxys sp.; prevalence was higher in S. brandtii and the mean intensity and mean abundance were higher in P. piraya (Table I). Table I. Prevalence (P), intensity range (IR), mean intensity (MI) and mean abundance (MA), with the respective standard deviation (SD), and site of infection (C = coelome, IC = intestinal cecum, E = stomach, AG = anterior gut, MG = middle gut, GB = gall bladder) of Spiroxys sp. from three hosts, piscivorous fish from Três Marias Reservoir, Upper São Francisco River, Brazil. Parasitic indexes of Spiroxys sp. Hosts P (%) IR MI±SD MA±SD Site of infection 12.9 1-6 1.93±1.49 0.25±0.83 C, IC, AG, GB Pygocentrus piraya 13.1 1-4 1.36±0.85 0.18±0.55 C, E, AG, MG Serrasalmus brandtii 1.8 1 1.0 0.018±0.13 C, MG Cichla kelberi The prevalence and mean abundance of Spiroxys sp. were not influenced by sex, total length and collection period of P. piraya. The prevalence and mean abundance of these larvae were also not influenced by either sex or collection period of S. brandtii. On the other hand, the prevalence and mean abundance of Spiroxys sp. were higher in smaller fish (Table II). As only two specimens of C. kelberi were parasitized by Spiroxys sp., it was not possible to conduct the statistical analyses for these specimens. Table II. Analysis of the parasitic indexes (P= prevalence, A= abundance) of Spiroxys sp. under the possible influence of sex, total length and collection period of two serrasalmine fish from Três Marias Reservoir, Upper São Francisco River, Minas Gerais, Brazil. Pygocentrus piraya Serrasalmus brandtii P A P A Χ2= 0.02 U= 1425.00 Χ2= 0.68 U= 2922.00 Sex p= 0.89 p= 0.84 p= 0.40 p= 0.52 r= -0.14 rs= 0.001 r= -0.94 rs= -0.25 Total length p= 0.74 p= 0.99 p= 0.0003* p= 0.001* 2 2 Χ = 0.62 U= 1318.00 Χ = 0.75 U= 3304.50 Collect period p= 0.43 p= 0.37 p= 0.38 p= 0.47 *Significant values: p<0.05; Χ2: Chi-square with Yates correction; U: Mann Whitney test; r: Pearson’s correlation; rs: Spearmann’s correlation rank. According to Moravec (1998), Spiroxys Schneider, 1866 is represented by seven species that infect freshwater chelid turtles of Central and North America. Of these, four have been reported in Mexico: Spiroxys contortus (Rudolphi, 1819), S. corti Caballero, 1935, S. susanae Caballero, 1941 and S. triretrodens Caballero & Zerecero, 1943. Because the morphological characteristics at the species level only become evident in adult specimens, it was only possible to identify the larvae to the genus level. Freshwater fishes are paratenic hosts of these larvae. Moravec (1998) suggested the possibility that the larvae of Spiroxys found in fish are S. contortus, a well-distributed and common species. Moravec et al. (1995) inventoried the Pan-American Journal of Aquatic Sciences (2009), 4(3): 306-311 First report of larval Spiroxys sp. in fishes from Três Marias Reservoir, Brazil Spiroxys present in the coelomic cavity, mesentery and intestines of Cichlasoma meeki (Brind, 1918), C. urophtalmus (Günther, 1862), Poecilia velifera (Regan, 1914), Poecilia sp. and Astyanax fasciatus (Cuvier, 1819) in the state of Yucatan, Mexico. Mendoza et al. (2004) reported these species in Dormitator maculatus (Bloch, 1792) (paratenic host) from Alvarado Lake, Mexico. In Brazil, Isaac et al. (2004) found larvae of Spiroxys in Gymnotus spp. caught in the Baía River in the State of Mato Grosso do Sul. In the present work, these larvae were found in the stomach, intestinal cecum, anterior and middle gut and gall bladder of the three host carnivores examined, two of them endemic serrasalmines of the São Francisco River Basin and one an allochtonous cichlid native to the Tocantins River Basin. Therefore, besides the possibility that smaller “piranha” ingest greater quantities of arthropods, our findings suggest that carnivorous fish also prey on foraging fish parasitized by larvae of Spiroxys sp. (one of the authors of this study previously found Spiroxys larvae in foraging fish in the Três Marias Reservoir) and are thus acting as paratenic hosts of these nematodes in Três Marias Reservoir. Despite the possibility of behavioral differences between male and female fish, mainly during the spawning season when females generally become stressed and vulnerable to infections, there was no difference in the parasitic indexes of the larvae of Spiroxys sp. between the male and female carnivorous fishes studied here. Spiroxys sp. was significantly more prevalent and abundant in smaller specimens of S. brandtii. This can be explained by the piscivorousinsectivorous feeding habit of juvenile “pirambebas”, as reported by Pompeu & Godinho (2003), including the intermediate host species of this nematode among the various arthropods eaten. According to Moravec (1998), fish act as paratenic hosts of these larvae (L3 or infective larvae of the definitive host), when feeding on infected aquatic insects (intermediate hosts), and the definitive hosts are freshwater chelid turtles. This study, besides the finding that smaller “pirambebas” can ingest greater quantities of arthropods, suggests that they also feed on foraging fish parasitized by larvae of Spiroxys sp., meaning these fish act as paratenic hosts of these nematodes in Três Marias Reservoir. According to Paperna (1996), if nematode larvae are not eliminated by the host’s immune system or by some regulatory system of the parasite intensity, they can remain viable for a long time until reaching their definitive hosts. The low intensity of Spiroxys sp. found in the three hosts analyzed, particularly in C. kelberi (where only two 309 specimens were parasitized), can be explained by the elimination of these larvae by the immune system of these hosts, or also by the sporadic feeding on these larvae by the fish species studied. The three carnivorous species were all infected by Spiroxys sp. larvae, but the parasitism pattern between the two serrasalmines endemic to the São Francisco River Basin was similar, that is, there was no quantitative difference between them. However, in C. kelberi these larvae were rare and the parasitism was probably accidental in this cichlid. Despite the results found in this study, it is probable that the diets of the serrasalmine fish (based on arthropods infected with Spiroxys larvae) were similar throughout the year in the Três Marias Reservoir since the prevalence and abundance of these larvae were not influenced by the fish collection period. Besides being considered definitive hosts of some parasite species, these findings indicate that the carnivorous fish from the Três Marias Reservoir analyzed in this study can be classified as paratenic hosts of Spiroxys larvae, indicating the complexity of the host-parasite relationship in the aquatic system in question. Acknowledgements The authors are grateful to Dr. Frantisek Moravec (Institute of Parasitology, Academy of Sciences of the Czech Republic) for identification of the nematode larvae; to Dr. Yoshimi Sato (EPT/CODEVASF) for the resources; to CEMIG/CODEVASF for the working arrangement; and the UFRRJ/IBAMA (MG) technical-scientific co-operative agreement for providing logistical and material support. We are also grateful to Dr. Philip Jon Scholl for the English revision of this manuscript. Michelle D. Santos was supported by a student fellowship from Conselho Nacional de Pesquisa e Desenvolvimento Tecnológico (CNPqBrazil); Marcia C. Albuquerque, Cassandra M. Monteiro and Nicole B. Ederli are grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes-Brazil) for their study grant. References Alvim, M. C. C. 1999. Caracterização alimentar da ictiofauna em um trecho do Alto rio São Francisco, município de Três Marias – MG. Master Thesis. Universidade Federal de São Carlos, São Carlos, Brazil, 83 p. Amato, J. F. R., Boeger, W.A. & Amato, S.B. 1991. Protocolos para laboratório – coleta e processamento de parasitos de pescado. Pan-American Journal of Aquatic Sciences (2009), 4(3): 306-311 310 Imprensa Universitária, Seropédica, 81 p. Braga, R. A. 1975. Ecologia e etologia das piranhas do nordeste do Brasil (Pisces – Serrasalmus Lacépède, 1803). DNOCS, Fortaleza, 268 p. Britski, H. A., Sato, Y. & Rosa, A. B. S. 1988. Manual de identificação de peixes da região de Três Marias (com chaves de identificação para os peixes da Bacia do São Francisco). 3a ed., CODEVASF, Brasília, 115 p. Bush, A. O., Aho, J. M. & Kennedy, C. R. 1990. Ecological versus phylogenetic determinants of helminth parasite community richness. Evolutionary Ecology, 4: 1-20. Bush, A. O., Lafferty, J. M. & Shostak, A. W. 1997. Parasitology meets ecology on its own terms: Margolis et al. revisited. Journal of Parasitology, 83: 575-583. Ferreira, R. M. A., Bazzoli, N., Rizzo, E. & Sato, Y. 1996. Aspectos reprodutivos da piranha Pygocentrus piraya (Teleostei, Characiformes), espécie nativa da bacia do rio São Francisco. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 48: 7176. Froese, R. & Pauly, D. 2007 (Eds.). FishBase – World Wide Web electronic publication, accessible at http://www.fishbase.org. (Accessed 01/18/2007). Gomes, J. H. C. 2002. Ecologia trófica de espécies de peixes do reservatório de Três Marias (MG). PhD. Thesis. Universidade Federal de São Carlos, São Carlos, Brazil, 142 p. Gomes, J. H. C. & Verani, J. R. 2003. Alimentação de espécies de peixes do reservatório de Três Marias. Pp. 195-227. In: Godinho, H. P. & Godinho, A. L. (Eds.). Águas, peixes e pescadores do São Francisco das Minas Gerais. Puc Minas, Belo Horizonte, 458 p. Isaac, A., Guidelli, G. M., França, J. G. & Pavanelli, G. C. 2004. Composição e estrututa das infracomunidades endoparasitárias de Gymnotus spp. (Pisces: Gymnotidae) do rio Baía, Mato Grosso do Sul, Brasil. Acta Scientiarum. Biological Sciences, 26: 453462. Jegú, M. 2003. Subfamily Serrasalminae. Pp. 182196. In: Reis, R. E., Kullander, S. O. & Ferraris, C. J. (Eds.). Checklist of the freshwater fishes of South and Central America. EDIPUCRS, Porto Alegre, 729 p. Kullander, S. O. & Ferreira, E. J. G. 2006. A review of the South American cichlid genus Cichla, M. D. SANTOS ET AL. with descriptions of nine species of Teleostei: Cichlidae. Ichthyological Exploration of Freshwaters, 17: 289-398. Magalhães, A. L. B., Sato, Y., Rizzo, E., Ferreira, R. M. A. & Bazzolli, N. 1996. Ciclo reprodutivo do tucunaré Cichla ocellaris (Schneider, 1801) na represa de Três Marias, MG. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 48: 85-92. Mendoza, J. M., Sarabia, D. O., López, R. C. & López, J. F. 2004. Helmintos del pez Dormitator maculatus (Osteichthyes: Eleotridae) de Alvarado, Veracruz, México. Revista de Biologia Tropical, 52: 393-396. Moravec, F. 1998. Nematodes of freshwater fishes of the Neotropical Region. Academy of Sciences of the Czech Republic, Praha, 464 p. Moravec, F., Vivas-Rodríguez, C., Scholz, T., Vargas-Vásquez, J., Mendoza-Franco, E., Schmitter-Soto, J. J. & Gonzáles-Solís, D. 1995. Nematodes parasitic in fishes of cenotes (= sinkholes) of the Peninsula of Yucatán, Mexico. Part 2. Larvae. Folia Parasitologica, 42: 199-210. Moravec, F., Santos, M. C. & Brasil-Sato, M. C. 2008. Redescription of Cystidicoloides fischeri based on specimens from piranhas in Brazil, and erection of a new genus (Nematoda: Cystidicolidae). Journal of Parasitology, 94: 889-897. Moreira, N. I. M. 1994. Alguns nematódeos parasitos de peixes na represa de Três Marias, Bacia do Rio São Francisco, Minas Gerais. Master Thesis. Universidade Federal de Minas Gerais, Minas Gerais, Brazil. 102 p. Paperna, I. 1996. Parasites, infections and diseases of fishes in África – An update. CIFA Technical Paper, 211 p. Pinkguni, M. 1997. Pirañas: cuidados – crianza – especies. Editorial Hispano Europea, Barcelona, 64 p. Pompeu, P. S., Godinho, H. P. 2003. Ictiofauna de três lagoas marginais do médio São Francisco. Pp. 167-181. In: Godinho, H. P. & Godinho, A. L. (Eds.). Águas, peixes e pescadores do São Francisco das Minas Gerais. PUC Minas, Belo Horizonte, 458 p. Sampaio, E. V., López, C. M. 2003. Limnologia física, química e biológica da represa de Três Marias e do São Francisco. Pp. 71-92. In: Godinho, H. P. & Godinho, A. L. (Eds.). Águas, peixes e pescadores do São Francisco das Minas Gerais. PUC Minas, Belo Horizonte, 458 p. Santos, M. D. 2008. Comunidades parasitárias de Pan-American Journal of Aquatic Sciences (2009), 4(3): 306-311 First report of larval Spiroxys sp. in fishes from Três Marias Reservoir, Brazil três espécies de peixes carnívoros do Reservatório de Três Marias, Alto Rio São Francisco, Minas Gerais, Brasil. PhD. Thesis. Universidade Federal Rural do Rio de Janeiro, 243 p. 311 Zar, J. H. 1996. Biostatistical Analysis. Prentice Hall, New Jersey. 662 p. Zaret, T. M. Life history and growth relationships of Cichla ocellaris, a predator South American Cichlid. Biotropica, 12: 144-157, 1980. Received February 2009 Accepted June 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 306-311 The nuisance of medusae (Cnidaria, Medusozoa) to shrimp trawls in central part of southern Brazilian Bight, from the perspective of artisanal fishermen RENATO M. NAGATA, MARIA A. HADDAD & MIODELI NOGUEIRA JR. Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, PR, Brasil, CEP: 81531-990. Email: renatonagata@gmail.com Abstract. Large aggregations of medusae hinder trawl fishing in coastal waters of several locations worldwide by clogging nets. In Paraná, scyphozoan medusae reach biomass peaks during springtime, when they saturate shrimp trawl nets. In order to assess possible disturbances to trawling caused by species of medusa, 48 fishermen who regularly use fishing trawls from 10 communities in the states of Paraná and Santa Catarina, southern Brazil, were interviewed. The general attitude of the respondents toward jellyfishes was found to be negative. Fishermen associated medusae, particularly the scyphomedusa Lychnorhiza lucerna, with net clogging. Two cubomedusa species, Chiropsalmus quadrumamus and Tamoya haplonema, and the hydromedusa Olindias sambaquiensis were singled out for the painful stings they cause. Large aggregations of medusae in fisheries shorten the duration of trawl hauls, displace hauls to areas further away from the landing ports and prompt fishermen to shift to other fishing gears such as anchored gillnet and drift net, amongst others. The fishermen hold a body of ethnobiological knowledge about jellyfish, such as the identification of toxic species and their seasonal occurrence, and have designed gimmicks to prevent medusae from entering the nets. Key words: Bloom, shrimp, Lychnorhiza lucerna; Olindias sambaquiensis; jellyfish Resumo. O entrave de medusas (Cnidaria, Medusozoa) aos arrastos de camarões na parte central do embaiamento sul do Brasil, pela perspectiva de pescadores artesanais. Ao entupirem redes de arrasto, grandes populações de macromedusas atrapalham a pesca de arrasto em águas costeiras de vários locais do mundo. No Paraná, as macromedusas Scyphozoa, quando atingem os picos de tamanho e biomassa durante a primavera, podem encher completamente redes de arrastos camaroeiros. Para verificar possíveis distúrbios gerados pelas espécies de medusas locais aos arrastos, 48 pescadores atuantes nessa arte de pesca foram entrevistados em 10 comunidades do litoral do Paraná e Santa Catarina. A visão geral dos entrevistados em relação às medusas é negativa. Os pescadores associaram principalmente a cifomedusa Lychnorhiza lucerna ao entupimento de redes. Duas espécies de cubomedusas (Chiropsalmus quadrumamus e Tamoya haplonema) e a hidromedusa Olindias sambaquiensis foram responsabilizadas por dolorosas queimaduras. Grandes agregações de medusas nos locais de pesca diminuem o tempo dos lances de arrastos, deslocam essas operações e causam a evasão para outras artes de pesca como o fundeio e o caceio. Os pescadores detêm um vasto conhecimento etnobiológico sobre as medusas, como o reconhecimento de espécies tóxicas, conhecimento sobre a sazonalidade das ocorrências e artifícios para evitar a entrada de medusas nas redes. Palavras-chave: Floração, camarão sete-barbas, Lychnorhiza lucerna; Olindias sambaquiensis; zooplâncton gelatinoso Introduction The occurrence of medusa or jellyfish (Cnidaria, Medusozoa) in high densities is a common phenomenon in coastal waters around the world and, occasionally, these animals completely dominate the planktonic biomass (e.g. Pagès et al. 1996, Benovic & Lucic 2001, Mills 2001). Due to their large size and the accidents with toxic species, Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 The nuisance of medusae to shrimp trawls from the perspective of artisanal fishermen the presence of jellyfish on beaches and shallow coastal waters is readily noticed by the public perception (review in Purcell et al. 2001, Haddad Jr. 2002, Purcell et al. 2007, Neves et al. 2007). Large medusa aggregations can interfere with fishing activities in two ways: 1) via food chain, either competing for food with commercial species (Ishi & Tanaka 2001, Purcell & Sturdvant 2001, Uye & Ueta 2004; Barz & Hirche 2005) or directly preying upon eggs and larvae of commercial fishing resources (review in Purcell & Arai 2001); 2) via clogging of nets, when large numbers of medusae are caught in a short period, causing stinging accidents (Guest 1959), damaging fishing gear (Brierley et al. 2001) and obstructing or displacing local fishing activities (Russell 1970, Brodeur et al. 2002, Uye & Ueta 2004; Kawahara et al. 2006a). Over the last decades, disturbances of fishing operations caused by large medusae appear to be correlated with recent population increases (Brierley et al. 2001, Brodeur et al. 2002, Uye & Ueta 2004; Kawahara et al. 2006a) and/or with the introduction of exotic species (Mills, 2001; Galil and Zenetus 2002; Graham et al. 2003). Such disturbances may be much more frequent than reported in the literature, as remarked by Purcell et al. (2007). In Brazil, Mianzan and Guerrero (2000) reported high biomass of the large hidrozoans Olindias sambaquiensis F. Müller, 1861 and Rhacostoma atlantica L. Agassiz, 1850, in Cabo de Santa Marta upwelling (28ºS), but quantitative data 313 on scyphomedusae is yet to be published. It is known, however, that macromedusae such the Hydrozoa O. sambaquiensis, the Cubozoa Chiropsalmus quadrumamus (F. Müller, 1859) and the three Scyphozoa Lychnorhiza lucerna Haeckel, 1880, Phyllorhiza punctata von Lendenfeld, 1884 and Chrysaora lactea Eschscholtz, 1829 occur in large numbers in trawl nets, stranded on the beach or floating on the water surface (Vannucci, 1951; Silveira and Cornelius 2000, Morandini et al. 2005; Haddad and Nogueira, 2006; Nogueira and Haddad 2006). On shallow waters (<20 m) of the South Brazilian Bight (SBB), small-scale shrimp trawls can be filled up with medusae and their biomass exceed that of all other animal groups (Graça-Lopes et al. 2002, Branco and Verani 2006). Recent investigations on the biology of medusae on the coast of Paraná, comprising more than eight years of monthly sampling, revealed that short ten-minute trawls could catch dozens of kilograms (Fig.1) of the scyphomedusa L. lucerna, mainly in springtime (Nogueira, Haddad and Nagata unpublished data). In the present study, face-to-face interviews with artisanal fishermen from 10 communities of Paraná and north of Santa Catarina were conducted in order to ascertain whether such high scyphomedusae biomass represents a nuisance to shrimp trawls. Only Uye & Ueta (2004) used the same method to report fishery losses caused by gelatinous plankton. Based on a fishermen poll, these authors analyzed the increase of Aurelia aurita populations in the Island Sea of Japan during the last 20 years. Figure 1. Catch of a small-scale shrimp trawl haul of 15 minutes, with abundance of Lychnorhiza lucerna in Paraná coast, Brazil. Courtesy of Cláudio D. Natividade. Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 314 Desspite increaseed attention given to meedusa disturbances to fishing worldwide (e.g. Mills 2001, 2 e al. 2006a,, Purcell et al. a 2007) andd the Kawahara et great abunddance of jelllyfish on thee Brazilian coast, c which cann potentiallly interferee with fisshing operations, no study haas investigateed the sociall and commerciall impacts in i Brazil. This T paper also documents, for the first f time, informationn on fishermen’ss ethnobiological knowlledge concerrning these gelatinnous animalss. Material and a Method ds Study Site. Thhe continenttal shelf is well R. M. NAGATA ET AL. deveeloped alonng the Souuthern Brazzilian Bightt (SBB B), reachingg 175 to 190 km width h. Along thee coasstline of the States of Parraná and San nta Catarina,, betw ween the beaaches of Ponntal do Sul and a Itapemaa do Norte N – SC (Fig. ( 2), locaal fishermen target moree than n 70 speciess of fish annd shellfish. The mainn fishiing resource in the area, however, is the sea-bobb shrim mp Xiphopeenaeus kroyeeri Heller, 1862, caughtt prim marily by boottom trawlinng carried out o by smalll traw wling vessels (Natividade et al. 2004). 2 Thiss pracctice is limitted to ca. 220 km off shore, wheree deptths are 6 metters in averagge. (Andrigu uetto-Filho ett al. 2006). 2 Figure 2. Sitte of interview wed fishing coommunities onn Paraná and Santa Catarinna states. 1- Poontal do Sul; 2 – Atami; 3–– Barranco;4- Shangrilá; 5– Ipanema; 6– Praia de Lestee; 7- Caieiras;; 8- Brejatuba; 9- Barra do S Saí; 10- Itapem ma do Norte. Coollection. Standarddized Datta questionnaires and opeen interviewss (Table I) were given to 48 trawl fishermen active in 10 communitiees of Paraná and northerrn Santa Catarina (Fig. 2), ovver given perriods from 2003 2 to 20044 and from 2006 to t 2007. Thhe following informationn was asked in thee questionnaaire: I) age of o the fisherm man; II) time off experiencee on fishingg activities; III) whether traw wling gear iss used exclussively or nott; IV) whether thhey report economic e loosses causedd by jellyfish; V) V whether large numbbers of jellyyfish cause an im mpediment too trawling; annd VI) amouunt of timee wasted when w trawlinng results in massivee jelly yfish captuures. Wheen answerss to thee quesstionnaire suggested s thhe presencee of largee med dusae concenntrations in tthe trawls, th he followingg information was also gathhered: A) reeferences too jelly yfish as a nuisance n to trawls; B)) reports off accidents causedd by toxic sspecies; and C) whetherr w shortenned in perio ods of largee timee of hauls was jelly yfish abundannce. For the category c of oopen intervieews, 20 locall expeert fishermenn, very experrienced in the practice off traw wl fishing, weere recommeended by reseearchers andd Pan-Americaan Journal of Aquatic A Sciennces (2009), 4(3): 312-325 315 The nuisance of medusae to shrimp trawls from the perspective of artisanal fishermen members of the communities (Table I). Formalin-fixed individuals of seven species of medusa frequently caught in trawl nets in the area (Lychnorhiza lucerna, Phyllorhiza punctata, Chrysaora lactea, Chiropsalmus quadrumamus, Tamoya haplonema F. Muller, 1859, Olindias sambaquiensis and Rhacostoma atlantica,) were displayed to the fishermen. After observing the material, the fishermen were asked the following questions about the various species: I) popular names and diagnostic characteristics; II) toxicity and treatments; III) seasonality, occurrence patterns and atypical occurrences; IV) biological aspects of medusae; and V) methods employed to prevent nuisance to trawl caused by large populations of medusae. The data was analyzed according to the model of union of all individual competences. Every piece of information concerning the subject was taken into account, and a quali-quantitative treatment of the data was conducted (Marques 1991). Table I. Number of fishermen interviewed on each fishing community from Paraná (PR) and north Santa Catarina (SC) coast. Community sampled Standardized interviews Opened interviews Pontal do Sul (PR) 8 4 Atami (PR) 2 1 Barranco (PR) 1 Shangrilá (PR) 7 6 Ipanema (PR) 1 Praia de Leste (PR) 7 1 Caieiras (PR) 5 2 Brejatuba (PR) 9 3 Barra do Saí (SC) 7 2 Itapema do Norte (SC) 1 1 Total 48 20 Results Standardized interviews with trawl fishermen. Among the 48 interviewed fishermen, ages varied from 26 to 70 years (mean of 44, standard deviation of ± 12.98). Half of them had been in the fishing trade for more than 30 years and 22.9% made exclusive use of trawling gear. Most fishermen (70.8%) claimed financial losses caused by high densities of medusae. A smaller percentage (29.17%) failed to correlate medusae with economic loss, but acknowledged time wasted and regarded the medusae as natural nuisances to the fishing activity (Table II). Table II. Answers about the jellyfish effect on fishing, following interviews (n = 48) to fishermen. Questions Do jellyfish cause economic losses to trawlers? Have you ever avoided fishing because of the large amount of jellyfish? Have you ever hurried your return from a fishery because of the large number of jellyfish? Among 34 respondents who claimed some economic loss, 73.5% reported a concomitant scarcity of shrimp in the same period (n=25) and 58.8% referred to extra fuel expenses to avoid medusae aggregations (n=20). Whenever a dramatic amount of large medusae was caught, 29.4% of the respondents (n=10) conveyed that they opened the cod-end, releasing all catches, including the shrimps. When the same 34 respondents were asked about what measures they took to mitigate the losses, 25% (n=8) answered none. Those who replied affirmatively (75%, n=26) said that they had Yes No 70,83% 58,33% 68,75% 29,17% 41,67% 31,25% changed their regular trawl activities to: I - fishing with gill nets (n=17); II - fishing at night, when the jellyfish move up to the surface (n=10); III - make use of gimmicks to reduce the amount of jellyfish during shrimp trawls (n=9); IV - explore other, more distant places such as Superagüi Island (n= 2). There was marked similarity in the following reports from the respondents (n=48): I – Influence on trawling – A view of medusae as pests, a cause of clogging of trawl nets, reduction in trawling time and time wasted. II - Accidents with toxic species – All Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 316 R. M. NAGATA ET AL. fishermen reported frequent accidents that cause pain in the arms and trunk, making work extremely arduous. III - By-catch – Medusae are more abundant in trawl nets than in other gears and can take up almost all the net space. IV – Seasonal Occurrence – All respondents observed the seasonality of medusae and reported inter-annual fluctuations. They did not report any recent frequency increase in massive occurrences of medusae. V – The duration of hauls - was significantly affected in periods of large amounts of medusae (Mann-Whitney, Z corrected = -8.47; p < 0.001; n=48), when shorter hauls were performed (Fig. 3). Figure 3. Maximum time of hauls performed by fishermen in periods of few medusae and in periods of many medusae (n=48). Open interviews with local experts. Even though distinct names were not assigned to all species displayed, the fishermen showed familiarity with the jellyfish. The characteristics used to define the species and their respective popular names are summarized in Table III. Table III. Popular names assigned by fishermen to the local large medusae and characteristics used for identification. Species Tamoya haplonema água-viva relojinho água-viva água-viva copo água-viva, bolota, cabeça d’água água-viva Rhacostoma atlantica Phyllorhiza punctata água-viva água-viva Olindias sambaquiensis Chrysaora lactea Chiropsalmus quadrumanus Lychnorhiza lucerna Characteristic according to interviews and frequency allocation of this feature. (n =20) Common name All species were referred to as “água-viva” (jellyfish). Other popular names such as medusa or “mãe d`água” were not mentioned. Only O. sambaquiensis was recognized by all respondents as “água-viva relojinho” (little watch jellyfish) or “relojinho”; however, five respondents also gave these same popular names to another species, R. Yellow radial canals (20) Cuboid bell, palmate pedalium very toxic (5) Hemispherical bell and cross-shaped stomach (11) Pedalium with a single long tentacle very toxic, called cords (11) Flat bell and consistent mesoglea (1) Brown hemispherical bell with white spots (8) atlantica. Some less careful fishermen confused Scyphozoa and Cubozoa species, simply assigning the name “água-viva” to them all, but such generalization was quite infrequent. Phyllorhiza punctata was pointed out as an unknown jellyfish until the years 2000-2001 by fishermen of Pontal do Sul, Caieiras and Brejatuba (n=11; 55%). The Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 The nuisance of medusae to shrimp trawls from the perspective of artisanal fishermen pedalia and tentacles of C. quadrumanus and T. haplonema, known as strings, were singled out as structures that cause painful stings by 5 and 11 respondents, respectively. Knowledge concerning the toxicity of 317 medusae to human skin was consistent with literature. Only three out of 20 respondents stated that all species cause stings, while the remaining associated toxicity with selected species only (Table IV). Table IV. Trawl fishermen’s knowledge on the toxicity of the species occurring in local trawls and a comparison with records in the literature (Haddad Jr. et al., 2002; Morandini et al. 2005).* Accidents according to the literature. Species Olindias sambaquiensis* Chrysaora lactea Chiropsalmus quadrumanus* Lychnorhiza lucerna Tamoya haplonema* Rhacostoma atlantica Phyllorhiza punctata Number of fishermen who attributed stings to the species (N=20) 20 3 9 3 16 4 3 According to 90% of the respondents (n=18), the peak of large jellyfish abundance occurs in late winter to early summer (September to January). Due to the open character of the interviews, some informants reported four months of abundance, while others reported only one. In order to equalize the weight of the answers in the analysis, to each answers was attributed a weight of 1 (one), and this value was then divided by the total number Toxicity for humans following literature High Moderate High Low (only at oral arms filaments) High Low Low of months mentioned in each interview. Thus, when only one month of high jellyfish concentrations was reported, a weight of 1 was attributed to this month; when two months were reported, the weight was 0.5; three months, mentioned, each one received 0.33; and four months, 0.25. Figure 4 shows the frequency of reports for each month of large abundance of medusae, as informed by the interviewers. Figure 4. Periods of greater abundance of jellyfish, as the open interviews (N=18). Throughout the open interviews, consensual biological knowledge emerged spontaneously from the accounts of various informants, highlighting their knowledge about interactions between medusae and fishing: (1) Medusae concentrate on the surface during the night and in the bottom during the day (N=14; 70%). According to the respondents, even though large numbers of medusae can be seen on the water surface at night, they are either rare or absent in night trawls. (2) Use of the crab Ocypode quadrata Fabricius 1787 (the Atlantic ghost crab, popularly known as “guaruçá” or “maria farinha”, flour mary) in the treatment of stings (N=14; 70%). The respondents reported the application of a macerate of this crab over the sting to relieve pain, especially in accidents involving children and sea bathers. Some of them stated that it is an effective medicine and they have made use of it in many occasions. This information was given by fishermen of all communities and also by local residents not involved in fishing activities. (3) Use of gimmicks in the trawl nets to reduce the catch of medusae was reported by 55% of the respondents (N=11). In order to avoid hauling Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 318 medusae, three types of modifications in the trawl nets were suggested, all of them reducing the vertical opening of the trawl to force the catch to concentrate in the bottom. They are: I – remove floats from the upper panel of the trawl (reported in Atami and Shangrilá); II - remove floats from the upper panel and set weights (reported in Pontal do Sul and Itapema do Norte); III – tie a rope between the upper and lower panels, restricting the opening of the mouth (reported in Shangrilá, Brejatuba and Barra do Saí). Discussion Standardized interviews with trawl fishermen. Some authors have briefly documented the presence of high concentrations of medusa in trawl catches in Brazil (Vannucci, 1954; GraçaLopes et al. 2002), but knowledge about the dynamics of small-vessel trawls is still more restricted in the area studied. Consequently, several aspects addressed in this paper had not been mentioned in previous contributions (AndriguettoFilho 2003; Chaves et al., 2002; Chaves and Robert 2003; Robert and Chaves, 2006; Andriguetto-Filho et al. 2006). Few respondents use trawling exclusively. Alternative fishing gear can be important in periods of large jellyfish aggregations, as for example setnets, which are not compromised by asggregarions. However, in the Sea of Japan, set-nets failed to avoid medusa nuisance (Kawahara et al. 2006a). Medusae reduce the amount of time spent on trawl fishing, as they either make fishermen return sooner (68.75%), or discourage their activity (58.3%) altogether. A behavioral model for the fishing daily routine of factory trawlers in the west coast of North America was described by Dorn (2001), who pointed out some hierarchical levels of decisions-making such as: 1) go out fishing or not; 2) select a patch or fishing ground on which to operate. As detected during the interviews, these decisions are also relevant to the fishing dynamics of the communities studied in this research. When jellyfish are in high concentrations, trawlers either avoid fishing altogether (58.3%) or target other fishing resources by using gillnets (35.4%). Scyphomedusa blooms also disrupt fisheries, such as those of Nemopilonema nomurai (Kishinouye 1922) in the Sea of Japan (Kawahara et al. 2006a) and Rhopilema nomadica Galil, Spanier, R. M. NAGATA ET AL. and Ferguson, 1990, in the Mediterranean Sea (Galil and Zenetus 2002). Some examples of the direct impact of medusae on trawling fisheries worldwide are summarized in Table V. Colonies of the bryozoan Membraniporopsis tubigera (Osburn, 1940) have been clogging trawl nets in southern Brazil (Gordon et al. 2006), apparently, in a similar manner to medusae. Dorn (2001) remarks that a trawl fisherman controls fuel expenditure by minimizing his transits between fishing locations. This behavior is equivalent to that of a predator foraging in his territory. During the interviews, fishermen reported that they can avoid hauling over medusa aggregations by communicating with each other by radio or visually, tracing the outline of a medusa umbrella with hand gestures. In addition, they tend to trawl at different depths to escape the aggregations. This locomotion between fishing grounds may result in waste of time and fuel. In the opinion of the respondents, the obliteration of trawl nets by medusae is noticeable in the power boost needed for pull of the boat. Also the net tends to float, failing to catch the shrimp as a demersal species, and the clogging causes a layer of water in the front of the mouth, which precludes the catching of other organisms. Consequently, hauls are compromised by the reduction in trawling time, similarly to what was observed by Kraeuter and Setzler (1975) in the estuaries of Georgia. Along the coast of Paraná, large catches of L. lucerna (>100kg) during 10 to 20 minute trawls either result in a major waste of time sorting out the catch, or end up with the entire volume of the trawl being discharged. L. lucerna causes fishing troubles also in the northern coast of Argentina, in summertime (Schiariti et al. 2008). Open interviews with local experts. Fishermen's knowledge about the toxicity of different species of medusa was consistent with scientific literature. In the Brazilian coast, the medusae responsible for the most painful envenomations, two cubozoan and the hydrozoan O. sambaquiensis, are the only species recorded in accidents with bathers by Haddad Jr. et al. (2002). Guest (1959), for instance, mentions that C. quadrumanus was a painful obstacle to fishermen of Matagorda Bay in Texas in some years where blooms occur. O. sambaquiensis is regarded as a nuisance to tourism in some regions of Argentina (Mianzan and Zamponi, 1988). Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 Species⁄ Class Local Year (months) Nuisiance to trawling Source - Clog fishing nets. - Fishing vessels shunned areas with high jellyfish biomass - Stings to fishermen. Brodeur et al. (2002) North America Chrysaora melanaster (Brandt, 1835) Scyphozoa Bering Sea 1990-1999 (Jun-Sep) Chiropsalmus quadrumanus Cubozoa Matagorda Bay (Texas, USA) 1955 and 1956 (Aug - Sep) Stomolophus meleagris (L. Agassiz 1862) Scyphozoa Estuaries of Georgia - USA 1972 (Abr-May) - Clog fishing nets. - Reduction of trawling time. Kraueter & Setzler (1975) Phyllorhiza punctata Scyphozoa Gulf of México 2000 (May – Sep) - Clog fishing nets. - Losses to comercial shrimp as high as US$ 10 million in 2000. Graham et al.(2003) Guest (1959) South America Southern Brazil coast Sep-Nov - Clog fishing nets. - Shorten the duration of trawl hauls. - Displacing these hauls to areas further away from the landing ports. - Fishermen temporarily shift the fishing gears to anchored gillnet and drift net. Present work L. lucerna Northern Argentina coast Dec-May - Clog⁄Damage fishing nets. - Reduce total fishing captures and catch quality. - Prevent fishermen to operate. Schiariti et al. (2008) Olindias sambaquiensis Hydrozoa Southern Brazil – Northern Argentina coast Jul-Oct - Clog fishing nets. - The author cite that shrimp move off shore from the aggregation of jellies. - Stings to fishermen. Vannucci (1951) Present work Aug.-Sep. - Clog⁄Burst fishing nets. - Collapse of pilchard fishery. Brierley et al. (2001) Africa Chrysaora hysoscella Linne, 1766 Namibian Benguela Scyphozoa 319 Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 Lychnorhiza lucerna Scyphozoa The nuisance of medusae to shrimp trawls from the perspective of artisanal fishermen Table V. Published reports of cnidarian jellyfish interfering with trawling operations around the world. 320 Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 Table V. Published reports of cnidarian jellyfish interfering with trawling operations around the world (continued). Species⁄ Class Local Year (months) Nuisiance to trawling Source Europe Periphylla periphylla (Perón & Lesueur, 1810) Scyphozoa Lurefjorden Fjord , Norway Late 1940´s , - Clog fishing nets. since 1973 (Oct- - Impeding trawl operations in the Nov and Aprperiod of high biomass. May) Fossa (1992) Aurelia sp. Scyphozoa North Atlantic of U.K. Abr-Aug Russell (1970) Rhizostoma octopus Vanhöffen 1906 Scyphozoa Black Sea - Clog⁄Burst fishing nets. - Displace hals to other areas. - Cod-end is open due to the weight. - Fishermen think that fish move away from the aggregation No available date - Clog fishing nets. Rhopilema nomadica autor? Scyphozoa Mediterranean coast of Israel Since mid 1980´s - Clog fishing nets. Lotan et al. (1992) (Jun-Sep) - Impeding trawl operations in periods of high biomass. Galil & Zenetos (2002) Netchaerff & Neu 1940 apud Russel (1970) Asia - Decreased catches in artisanal and industrial fisheries. Daryanabard & Dawson (2008) - Damage to fishing gear. Crambionella orsini (Vanhöffen 1888) Scyphozoa Gulf of Oman and Persian Gulf Cyanea capillata (Linnaeus, 1758) Scyphozoa Yangtze Estuary, China Since 2004 (May) - Clog fishing nets. Xian et al. (2005) Aurelia sp. Scyphozoa Seto inland Sea, Japan Summer Uye & Ueta (2004) Uye & Shimauchi (2005) Nemopilonema nomurai Scyphozoa Along coast of Japan 2002 – 2006 (Aug-Dec) - Clog⁄Burst fishing nets. - Declining catches of zooplanctivorous fishes. - Reducing catches quality. - Stings to fishermen. - Increased labor to remove medusae from the nets. - Clog⁄Burst fishing nets. - Lower catches of finfish. - High mortality of finfish by nematocyst venom, and lower commercial value. - Increased labor to remove medusae from the nets. - Higher risk of capsizing trawl boats - Stings to fishermen. Kawahara et al. (2006) R. M. NAGATA ET AL. The nuisance of medusae to shrimp trawls from the perspective of artisanal fishermen Accidents with fishermen happen during sorting of the catch, when urticating substances are released from the nematocysts or when they inadvertently touch certain parts of the animal’s body, especially the tentacles. Structures such as tentacles and pedalia of cubomedusae, especially of T. haplonema, called “strings”, are avoided for their high toxicity, which is justifiable by the greater concentration of nematocysts on those structures (Arai, 1997). Fishermen interviewed in this study did not associate the abundant L. lucerna with stings, eruptions or pain symptoms, although its oral arms filaments, when healthy, can cause little pain to hand human skin (Haddad personal observation). The absence of tentacles in Rhizostomeae scyphozoan medusae, like L. lucerna, generally results in reduced stings. However, three species of this same group, Rhopilema hispidum, R. esculentum and Nemopilema nomurai, highly exploited for human consumption as a delicacy in China, Japan and other Asian countries, have been attributed to accidents by fishermen in Japan (Kawahara et al. 2006b). Nematocyst toxins may diminish the market value or even preclude the commerce of exploitable species (Kawahara et al. 2006a; Purcell et al. 2007). The seasonality in the life cycle of large medusae is a widely known phenomenon (Russell 1970; Arai 1997) and empiric observations along decades of trawl fishing provided the respondents with knowledge about the temporal fluctuation in medusa biomass. The months of large medusa biomass peaks indicated by the fishermen (Fig. 4) are the same cited in the literature of great abundance of the scyphomedusa L. lucerna (Silveira and Cornelius 2000; Morandini 2003; Nogueira and Haddad, unpublished data). This observation suggests that trawlers are aware not only of the periodicity of their target resources, but also of the other conspicuous elements of fishery. Although the bathymetric distribution of L. lucerna is not known, aggregations of this species possibly overlap with the occurrence zone of the shrimp X. kroyeri, which is limited to a maximum depth of 20 m (Andriguetto Filho et al. 2006). As revealed by the fishery experts, the use of a macerate made with the crab Ocypode quadrata is a form of treatment against stings commonly practiced by the communities in the coast of Paraná. Fishermen from Cananéia and Guarujá, southern coast of São Paulo, make a similar use of it (Sérgio Stampar, personal communication). There is no mention of such treatment for cnidarian’s stings in the literature. However, an adequate treatment can be conducted with a cold compress of saltwater or cold packs, and intramuscularly dipirona for pain 321 control (Haddad Jr. et al. 2002). Diel vertical migration (DVM) is documented for the great majority of zooplankton taxa, including medusae (Youngblouth and Blanstedt, 2001; Hays 2003; Sparks et al., 2005). Common migration patterns usually involve individuals staying in deeper regions of the water column during the day and moving closer to the water surface at night. This behavior was reported for the medusae by 70% of the respondents and 30% of them pointed out that the ascent to the surface would be favorable for trawling during the night. The species that display such behavior were not distinguished in the interviews. In the area studied, large medusae aggregations have not been recorded on the water surface, at least during the day, with the exception of the zooxanthellate P. punctata (Haddad and Nogueira, 2006). All modifications in the trawl nets, believed to reduce the intake of jellyfish, are based on the fishermen’s perspective about the position of the animals in the water column. According to them, the shrimp X. kroyeri is a demersal species, while medusae would be found in mid-water. Thus, upon restricting the vertical opening of the trawl net – by removing the floats, placing weights or bringing the upper and lower panels close together with ropes – fewer medusas would be caught and the shrimp catch would not be affected. Contrary to the respondents' perception of medusae occurring in the mid-water position, acoustic surveys in Rio de la Plata estuary demonstrated aggregates of L. lucerna close to the bottom (Alvarez-Colombo et al. 2003). Along the coasts of Paraná and north of Santa Catarina, several trawl nets operating without floats have been observed, but other modifications have not. Jellyfish-exclusion devices of the “blubberchute” type (Broadhurst and Kennelly 1996) or Jellyfish Excluder for Towed Fishing Gear “JET” (Matsushita and Honda 2006) have been developed in Australia and Japan. Such devices, set inside the trawl net, filter away larger organisms, excluding them through an exit window in the back of the net. Many reports on trawl net clogging concern introduced medusae (Galil et al. 1990; Graham et al. 2003), a fact not observed in this study. The scyphomedusa P. punctata reappeared in the coast of Paraná in 2001, occurring in great abundance during summer and early autumn (Haddad and Nogueira 2006). The respondents noticed the appearance of this species, previously unknown to them (55%), but stated that it does not interfere with local trawls, because this scyphomedusa is more often encountered on the superficial layer of water (Haddad and Nogueira 2006). Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 322 Large Scyphozoa medusae (around 18 species, mainly in the Order Rhizostomeae) are a culinary delicacy in Southeast Asia, and over a thousand of years they have been locally exploited (Omori & Nakano, 2001, Schiariti 2008). The jellyfish market is steadily increased, particularly in Japan, Taiwan, South Korea, Indonesia, Malaysia and China. Commercial catches have increased since the 1970´s and regularly exceed 300 000 tons⁄year in wet weight (Omori and Nakano 2001). Medusae are fished in many places and countries of Southeast Asia, like Philippines, Vietnam, Malaysia, Thailand, Indonesia, Singapore and Myanmar and, more recently, small-scale exploitation has begun in Australia, India, Mexico, Turkey and the United States (Hsieh et al. 2001). By adding value to jelly discards, important benefits to fisheries and environment may be created. A trawl-clogger, Stomolophus meleagris (L. Agassiz 1862) in the coastal waters of U. S. A. is a successful commercial example (Kraueter and Setzler, 1975, Hsieh, 2001). Recent investigations on the development of jellyfish fisheries in the north of Argentina revealed that the costs involved in harvesting and processing L. lucerna are relatively low (Schiariti, 2008). The seasonal high biomass of this medusa in the south of Brazil and north of Argentina, the world requirements to attenuate pressure on individual fishing stocks and the increasing demand for this kind of food products points L. lucerna as a potential new resource to future sustainable exploration. According to the results obtained by this study, the scyphomedusa L. lucerna is responsible for clogging trawl nets in the coast of Paraná due to its large spring biomass, causing a variety of disturbances to the routine of that fishing gear. The hydromedusa O. sambaquiensis and the cubomedusae T. haplonema and C. quadrumamus are the main species responsible for accidents with fishermen. The records of local knowledge on large medusae prompt other studies to evaluate the effectiveness of modifications in trawl nets suggested by fishermen to exclude medusae. 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Received February 2009 Accepted July 2009 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 312-325 Comportamento Predatório Ex situ do Caranguejo Menippe nodifrons Stimpson, 1859 (Decapoda, Brachyura) sobre Moluscos Gastrópodes GIVANILDO XIMENES SANTANA1, ANTÔNIO ADAUTO FONTELES FILHO1, LUIS ERNESTO ARRUDA BEZERRA2 & HELENA MATTHEWS-CASCON1,3 1 Pós-Graduação em Ciências Marinhas Tropicais, Instituto de Ciências do Mar (LABOMAR), Universidade Federal do Ceará, Av. da Abolição, 3207 - Meireles - CEP: 60165-081, Fortaleza, Ceará - Brasil. Email: biogil@gmail.com 2 Pós-Graduação em Oceanografia, Departamento de Oceanografia, Universidade Federal de Pernambuco, Av. da Arquitetura, S/N, Cidade Universitária. 50670-901 Recife, Pernambuco – Brasil. 3 Departamento de Biologia, Universidade Federal do Ceará, Campus do Pici, Fortaleza, Ceará - Brasil 60455-760. Abstract. Predatory Behaviour Ex situ of the Stone Crab Menippe nodifrons Stimpson, 1859 (Decapoda, Brachyura) on Gastropods in Laboratory. Laboratory experiments were used to study the effect predation of the crab Menippe nodifrons Stimpson, 1859 on gastropods Stramonita haemastoma Linnaeus, 1758 Tegula viridula Gmelin, 1791 and Neritina virginea Linnaeus, 1758. The observed aspects had been of prey preference, handling time, predation techniques, prey critical size and chelal biomechanic analysis of the crabs. The crabs and the clams had been collected in the beach of the Pacheco, located in the city of Caucaia-Ce. Menippe nodifrons preferred Neritina virginea over both S. haemastoma and Tegula viridula, and S. haemastoma was strongly preferred over T. viridula. The males crabs preyed more heavily upon Neritina virginea than on both gastropods Stramonita haemastoma and Tegula viridula, while the females had eaten indistinctly the three gastropods. There were differences in hadling times between Neritina virginea, Stramonita haemastoma and Tegula viridula. The mean critical size for Neritina virginea was significantly smaller than for Stramonita haemastoma, which in turn was smaller than for Tegula viridula. The claws of the crab Menippe nodifrons are well designed for breaking shells. Differences in the morphological and mechanical features of crab claws reflect their function and account for many of the observed differences in prey handling techniques and foraging behaviour. Key words: Prey preference, Predation, Molluscs Resumo. Foi realizado experimento em laboratório para observar a predação do caranguejo Menippe nodifrons sobre três espécies de moluscos gastrópodes: Stramonita haemastoma, Tegula viridula e Neritina virginea. Foram obervados a preferência pela presa, tempo de predação e manipulação da presa, tamanho crítico da presa, e análise biomecânica das quelas. Os caranguejos e os moluscos foram coletados na praia do Pacheco, localizada no município de Caucaia-Ce. Menippe nodifrons alimentou-se das três espécies de gastrópodes, com uma maior preferência alimentar por N. virginea em relação aos outros moluscos oferecidos S. haemastoma e T. viridula. A predação pelos caranguejos foi maior sobre S. haemastoma, do que em T. viridula. Os machos predaram mais ativamente Neritina virginea, enquanto as fêmeas não tiveram preferência por nenhuma das presas oferecidas, predando-as indistintamente. O tempo de manipulação foi menor para N. virginea do que para S. haemastoma e T. viridula. O tamanho crítico da presa foi menor para N. virginea, seguida por S. haemastoma e T. viridula respectivamente. As quelas são desenhadas para quebrar conchas dos moluscos. O comportamento predatório do caranguejo Menippe nodifrons está diretamente relacionado ao nível de especialização de suas quelas, das características morfológicas e vulnerabilidade de suas presas. Palavras-Chave: Preferência pela presa, Predação, Moluscos Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 Comportamento predatório Ex situ do caranguejo Menippe nodifrons sobre Moluscos Gastrópodes Introdução Entre as espécies de caranguejos observadas por Vermeij (1977) como importantes predadores de moluscos gastrópodes, destacam-se as pertencentes às famílias Xanthidae, Menippidae e Carpilidae, em especial os dos gêneros Carpilius Leach, 1823; Eriphia Latreille, 1817; Ozius H. Milne Edwards, 1834; Lydia Gistel, 1848; Galene de Haan, 1833 e Menippe de Haan, 1833. Caranguejos do gênero Menippe são considerados excelentes predadores por serem animais de médio a grande porte (Bert 1992) e, principalmente, por possuírem quelas especializadas em quebrar e abrir conchas de muitos moluscos (Lindberg & Marshall 1984). Os caranguejos quebram as conchas de suas presas de duas maneiras, por tritura/esmagamento (“crushing”), e por descascamento (“peeling”). A primeira consiste em comprimir a concha entre duas superfícies duras, como por exemplo, entre os dedos fixo e móvel das quelas. O segundo tipo de quebra consiste no descascamento, no qual a borda de crescimento da concha (o lábio externo nas conchas de gastrópodes e a superfície livre das valvas de bivalves) é atacada pelo caranguejo. Começando pelo lábio, o caranguejo quebra a concha pedaço por pedaço em direção ao ápice, até os tecidos serem expostos para o consumo (Palmer 1979, 1999). Crustáceos decápodos moluscívoros têm mostrado possuir um importante papel no processo de evolução das conchas através da predação utilizando a técnica de esmagamento (Berteness & Cunningham 1981). O caranguejo Menippe nodifrons Stimpson, 1859 é uma espécie encontrada no litoral brasileiro, ocorrendo em quase toda a sua extensão, desde o Maranhão até a costa de Santa Catarina, podendo ser encontrado ainda na Florida, Antilhas, Norte da América do Sul, Guianas, Atlântico Oriental e África Tropical (Coelho 1967, 1972; Melo 1996). Esse caranguejo, característico de costões rochosos, recifes de arenito e estuários, pode ser encontrado no médio-litoral em praias de águas rasas e nas poças de marés; sob as rochas, entre fendas e pilares de atracadouros ou, ainda, na base de plantas de mangue, madeira podre no solo e bancos de ostras (Coelho 1967; Furtado-Ogawa 1972; Fausto-Filho 1976; Melo 1996). Apesar da abundância e relativa facilidade de coleta, trabalhos realizados com a espécie M. nodifrons no Brasil são escassos (Castro & Araújo 1978; Oshiro 1999, Fransozo et al. 1999), e os aspectos de sua biologia e ecologia são pouco conhecidos, particularmente aqueles relativos à sua dieta e ao seu comportamento predatório (Turra et 327 al. 2005; Madambashi et al. 2005). Com isso, esse trabalho teve como objetivo estudar o comportamento predatório do caranguejo M. nodifrons em condições de laboratório, sobre três espécies de moluscos gastrópodes: Stramonita haemastoma (Linnaeus, 1758), Tegula viridula (Gmelin, 1791) e Neritina virginea (Linnaeus, 1758), observando sua preferência alimentar, tempo de predação que o caranguejo investe em cada espécie de presa, análise biomecânica das quelas e do tamanho crítico das presas e técnicas de manipulação empregadas. Materiais e Métodos Coleta dos caranguejos e moluscos. Os caranguejos e moluscos foram coletados manualmente nos meses de março e julho de 2004, na zona entre-marés da Praia do Pacheco, Município de Caucaia, Ceará (3°44’S, 38°39’W). Caranguejos machos e fêmeas foram capturados aleatoriamente, enquanto no caso dos moluscos, apenas espécimes que não possuíam conchas danificadas foram coletados. Os animais foram acondicionados em recipientes contendo água marinha e levados ao Laboratório de Invertebrados Marinhos do Departamento de Biologia, da Universidade Federal do Ceará. Os caranguejos foram aclimatizados em aquários individuais de 5 litros e os moluscos em aquários de 20 litros, ambos com aeração artificial, contendo água do mar, em temperatura ambiente (37°C) e salinidade de 35. Todos os animais coletados foram medidos com o auxílio de um paquímetro (± 0,01mm de acurácia). No caso dos caranguejos, foram medidos comprimento (do sulco entre os pedúnculos oculares na margem anterior até o final da margem posterior) e largura do cefalotórax (entre as margens ântero-laterais na altura do 3º espinho); além do comprimento (da ponta do própodo ou dedo fixo até a linha de junção entre o carpo) e largura das quelas (porção mais alargada da palma). Já as presas foram mensuradas da seguinte forma: Stramonita haemastoma da espira ao canal sifonal anterior; Tegula viridula e Neritina virginea da espira até o lábio externo. Experimento de preferência alimentar. Um total de 23 caranguejos, sendo 9 machos e 14 fêmeas, com comprimento do cefalotórax variando de 20-40mm, foram colocados individualmente em um aquário de 5L e deixados por 48h sem alimento. Após esse período foram acrescentadas em cada aquário, as três espécies de presas. Para cada molusco retirado após a predação, era verificado se a concha fora danificada ou se apresentava cicatrizes. Esse experimento teve duração de um Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 328 mês. As presas tinham os seguintes intervalos de classes de tamanho: S. haemastoma (10-25 mm); T. viridula (10-20 mm) e N. virginea (10-15 mm). Para as análises de preferência alimentar por M. nodifrons, foi utilizado o pacote estatístico Bioestat 2.0 (Ayres et al. 2000), sendo aplicado nesse tratamento o teste χ2 (qui-quadrado) nãoparamétrico para cálculo de proporções. Foram consideradas as seguintes hipóteses para o experimento de preferência alimentar: Ho: Não existe preferência alimentar da espécie M. nodifrons por uma das presas S. haemastoma, T. viridula ou N. virginea. Ha: Existe preferência alimentar da espécie M. nodifrons por uma das presas S. haemastoma, T. viridula ou N. virginea. Entre os sexos as hipóteses testadas para a preferência alimentar foram: Ho: Não existe preferência alimentar em machos de M. nodifrons por S. haemastoma, T. viridula ou N. virginea. Ha: Existe preferência alimentar em machos de M. nodifrons por S. haemastoma, T. viridula e N. virginea. Ho: Não existe preferência alimentar em fêmeas de M. nodifrons por S. haemastoma, T. viridula ou N. virginea. Ha: Existe preferência alimentar em fêmeas de M. nodifrons por S. haemastoma, T. viridula ou N. virginea. Experimento de tempo de predação e Manipulação das presas. O experimento foi realizado com 16 espécimes de M. nodifrons, (10 fêmeas e 6 machos). Assim como no experimento de preferência, os caranguejos foram acondicionados em aquários individuais, nas mesmas condições descritas anteriormente. A duração do experimento foi de um mês e as observações realizadas a cada duas horas. Cada uma das espécies de molusco foi oferecida por 10 dias aos caranguejos até o final do experimento. Para a determinação do tempo de predação das presas por parte do caranguejo, foi observado o tempo de inicio da captura até a dispensa da concha. Em seguida, as conchas eram examinadas para se observar a efetividade da predação pelos caranguejos, ou seja, o consumo das partes viscerais dos moluscos. Somente foram analisadas as conchas vazias ou parcialmente consumidas. O tempo foi marcado com o uso de cronômetro e calculado através da diferença entre os intervalos inicial e final da predação. Todos os tempos foram transformados de horas para minutos. Para avaliar se houve diferença entre os sexos de Menippe nodifrons em relação ao tempo de G. X. SANTANA ET AL. predação sobre os três tipos de presas oferecidas, foi realizado o teste t de Student (Zar 1999). A variável sob teste é o tempo de predação, em minutos, medido separadamente entre machos e fêmeas de M. nodifrons sobre as três espécies de presa. Para o experimento de tempo de predação foram testadas as seguintes hipóteses: Ho = machos e fêmeas utilizam o mesmo tempo de predação sobre S. haemastoma Ha = machos e fêmeas utilizam tempos de predação diferentes sobre S. haemastoma Ho = machos e fêmeas utilizam o mesmo tempo de predação sobre T. viridula Ha = machos e fêmeas utilizam tempos de predação diferentes sobre T. viridula Ho = machos e fêmeas utilizam o mesmo tempo de predação sobre N. virginea Ha = machos e fêmeas utilizam tempos de predação diferentes sobre N. virginea Também foi realizado o teste de KruskallWallis (Zar 1999) para avaliar se o tipo de presa interfere no tempo de predação pelo caranguejo Menippe nodifrons. A variável sob teste é o tempo de predação, medido em minutos, da espécie M. nodifrons sobre as três espécies de presa. As seguintes hipóteses foram testadas: Ho = o tempo de predação é igual sobre S. haemastoma, T. viridula e N. virginea Ha = o tempo de predação é diferente sobre S. haemastoma, T. viridula e N. virginea Tamanho crítico da presa e Espessura das conchas O tamanho crítico foi calculado através de uma razão simples entre a média dos tamanhos da largura (tamanho da volta corporal) das presas (LP) e dos comprimentos da quelas maiores (QM) dos caranguejos (Vermeij 1976; Berteness & Cunningham 1981; Boulding 1984; Smallegange & Van Der Merr 2003). Segundo Smallegange & Van Der Merr (2003), esse valor indica quantas vezes a largura da presa é maior que o comprimento da quela e o quanto esse parâmetro é importante na escolha das presas e na manipulação das mesmas. O tamanho crítico será usado para auxiliar na caracterização das técnicas aplicadas pelos caranguejos diante da forma da concha das três presas oferecidas. As espessuras das conchas foram verificadas através da mensuração das espessuras dos lábios interno (medida do lábio adjacente a columela) e externo (medida do lábio oposto a columela) das conchas em cada espécie de gastrópodo. Foi utilizado um paquímetro de ± 0,01mm de acurácia para anotação das medidas. No total foram amostradas 20 conchas de cada presa e Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 Comportamento predatório Ex situ do caranguejo Menippe nodifrons sobre Moluscos Gastrópodes resistentes à predação por caranguejos moluscívoros (Seed & Hughes, 1995, 1997; Yamanda & Boulding, 1998). Considera-se um valor de VM > 0,3 para espécies de caranguejos com quelas especializadas em quebrar conchas duras e resistentes. Quando a VM é menor que 0,3 os caranguejos são considerados pouco especialistas na quebra de conchas mais duras (Warner & Jones, 1976; Bronw et al., 1979; Elner & Campbell, 1981). Foi calculado o valor da vantagem mecânica nas quelas de 18 caranguejos, entre machos (n = 09) e fêmeas (n = 09), em seguida calcularam-se as médias dos valores obtidos. Resultados Preferência alimentar. A espécie Menippe nodifrons consumiu as três espécies de presas oferecidas (Fig. 1) por ordem de preferência: Neritina virginea (44,9%); Stramonita haemastoma (29,7%) e Tegula viridula (25,4%), o teste χ2 mostrou significância com valor igual a 8,73 (g.l. = 2) para α = 0,05 e p = 0,0127. Dessa forma, aceitase a hipótese alternativa (Ha), de que existe preferência alimentar do caranguejo M. nodifrons por uma das presas. Neritina virginea Presas Thais haemastom a Tegula viridula calculada as médias das medidas dos lábios interno e externo para cada espécie conforme Trussell (1996). As médias das medidas do lábio externo foram analisadas estatísticamente usando ANOVA: 1 critério, seguido do teste de Tukey HSD para comparações múltiplas (Zaar, 1999), para testar a hipótese nula (H0), de que as médias das espessuras das conchas das presas são similares (μ1 = μ2 = μ3), ou a alternativa (Ha), no qual as médias são diferentes (μ1 ≠ μ2 ≠ μ3). Análise biomecânica das quelas. Foram observadas as características morfológicas e biomecânicas das quelas de M. nodifrons. As análises consistiram em descrever a forma da dentição localizada na superfície dos dedos fixo e do dátilo (móvel). Também foi realizado cálculo da vantagem mecânica das quelas. A vantagem mecânica (VM) é um valor adimensional calculado através de uma razão simples L1/L2, onde L1 é a distância entre o ponto de rotação do dátilo (no eixo fixo) até o ponto de inserção do apodema (tendão dos grandes músculos das quelas) e L2 a distância do ponto de rotação até a ponta do dátilo. Esse parâmetro está associado com o nível de especialização das quelas em quebrar conchas 329 0 10 20 30 40 50 Freqüência (%) Figura 1. Frequência de consumo das presas Stramonita haemastoma, Tegula viridula e Neritina virginea pelo caranguejo Menippe nodirons. Entre os sexos a preferência alimentar (Fig. 2) observada em machos de M. nodifrons mostrou alta significância estatística com o teste χ2, para o valor calculado igual a 16,28 (g.l. = 2); p < 0,01. Dessa forma, aceita-se a hipótese alternativa (Ha) de que machos de M. nodifrons preferem uma das três presas oferecidas. A ordem de preferência alimentar entre machos de M. nodifrons por uma das presas foi: N. virginea (n = 34), S. haemastoma (n = 15) e T. viridula (n = 10). Para as fêmeas de M. nodifrons, não houve significância para o teste χ2, sendo o valor calculado (χ2 = 0,17, g.l = 2, α = 0,05) menor que o valor esperado. Sendo assim, aceita-se a hipótese nula (Ho), onde fêmeas do caranguejo M. nodifrons não tiveram preferência alimentar por nenhuma das três presas oferecidas, selecionando-as igualmente durante a predação, S. haemastoma (n = 26), T. viridula (n = 25) e N. virginea (n = 28). Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 330 G. X. SANTANA ET AL. NÚMERO D E PRESAS CONSUMIDAS 40 34 35 Machos Fêmeas 30 28 26 25 25 20 15 15 10 10 5 0 Neritina virginea Stramonita haemastoma Tegula viridula PRESAS Figura 2. Preferência alimentar do caranguejo Menippe nodifrons pelas presas oferecidas em relação ao sexo. Tempo de Predação. Os resultados do teste t mostraram que entre machos e fêmeas de M. nodifrons não houve diferença significativa em relação ao tempo de predação sobre S. haemastoma (t = 0,505; p = 0,620), T. viridula (t = - 0,088; p = 0,932) e N. virginea (t = 0,056; p = 0,956). Dessa forma, aceita-se a hipótese nula (Ho), onde machos e fêmeas de M. nodifrons utilizam o mesmo tempo de predação para capturar e consumir S. haemastoma, T. viridula e N. virginea. Considerando-se o teste de Kruskall-Wallis para avaliar se o tipo de presa interfere no tempo de predação do caranguejo M. nodifrons, os resultados expressos na Figura 3 mostram que a espécie utiliza tempos de predação diferentes (hipótese alternativa) sobre S. haemastoma, (106,1 min), T. viridula (120,7 min) e N. virginea (44,2 min), com base no valor de H = 39,85 com elevada significância estatística, ao nível de 1% (p< 0,01); g.l. = 2. 140 120,7 120 TEMPO DE PREDAÇà O (min ) 106,1 100 80 60 44,2 40 20 0 Neritina virginea Stramonita haemastoma Tegula viridula PRESAS Figura 3. Tempo de manipulação requerido pelo caranguejo Menippe nodifrons sobre as três presas oferecidas. A Figura 4 mostra a relação entre a preferência alimentar e o tempo de manipulação das presas conforme os resultados obtidos para o caranguejo M. nodifrons. O tempo de manipulação aumenta enquanto a preferência alimentar diminui para as diferentes presas oferecidas. Manipulação das presas. Menippe nodifrons manipulou as três espécies de presas usando técnicas de esmagamento e também de descascamento (Fig. 5). A técnica de esmagamento Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 331 Comportamento predatório Ex situ do caranguejo Menippe nodifrons sobre Moluscos Gastrópodes consistiu em capturar a presa pela sua volta corporal (Fig. 5c, 5d) e abraçá-la, empurrando-a contra seu corpo. Enquanto isso, os primeiros e segundos pares de pereiópodos (patas locomotoras) auxiliavam na manipulação da presa e levavam os moluscos até os apêndices bucais (maxilípedes). A quela maior quebrava a concha dos gastrópodes entre o dedo fixo e o dátilo no meio da volta corporal, ou então, como ocorreu algumas vezes em S. haemastoma (Fig. 5a, 5b), a concha dos moluscos era quebrada com essa quela através do ápice. Quando a presa era capturada, a quela menor era inserida na abertura labial da concha, enquanto o caranguejo tentava quebrá-la com a maior quela através da técnica de esmagamento. O esmagamento ocorreu em todas as presas, porém em Neritina virginea essa técnica foi predominante, não ocorrendo descascamento. 50 14 0 44,9 120,7 45 Freqüência 12 0 10 0 35 29,7 30 25,4 80 25 60 20 44,2 15 TEMPO DE PREDAÇÃO (min) FREQÜÊNCIA DE PREDAÇÃO (%) Tempo 106,1 40 40 10 20 5 0 0 Neritina virginea Stramonita haemas toma Tegula viridula PRESAS Figura 4. Relação entre tempo de manipulação e preferência alimentar do caranguejo Menippe nodifrons sobre as três espécies de presas oferecidas. Por outro lado, em S. haemastoma e T. viridula a técnica predominante foi o descascamento, ocorrendo o esmagamento poucas vezes (Fig. 5c, 5d, 5e, 5f). Ao fazerem uso da técnica de descascamento, os caranguejos reposicionavam a concha, inseriam o dedo fixo e o dátilo da quela maior entre a abertura do lábio externo da concha, apoiando a concha com a quela menor e os primeiros pares de pereiópodos. Algumas vezes, os caranguejos faziam uso da quela menor para aplicar o descascamento. Em seguida, eles raspavam e cortavam essa região do lábio externo da concha para facilitar a exposição do conteúdo visceral do gastrópode, que podia ser consumido total ou parcialmente pelos apêndices bucais. Quando as presas eram S. haemastoma e T. viridula, caranguejos menores sempre realizavam a técnica de descascamento, já os caranguejos maiores fizeram uso, algumas vezes, do esmagamento. Tanto os caranguejos grandes, como os pequenos utilizaram a técnica de esmagamento para predar N. virginea (Fig. 5g, 5h). Tamanho crítico da presa e Espessura das conchas. Os valores abaixo mostram as médias para largura das presas Stramonita haemastoma, Tegula viridula e Neritina virginea e comprimento da quela maior do caranguejo Menippe nodifrons. O gastrópode Neritina virginea foi a espécie que apresentou o menor tamanho crítico (TCP = 0,34), em seguida obteve-se os respectivos valores para S. haemastoma (TCP = 0,38) e T. viridula (TCP = 0,50). No quadro I observa-se os resultados para os valores das médias calculadas para as espessuras do lábio interno e para o lábio externo. A espessura da concha para o lábio externo (região onde ocorre a manipulação por peeling e mais susceptível ao ataque pelo caranguejo) foi menor em Neritina virginea (μ1 = 0,22), seguida pelas médias de Tegula viridula (μ2 = 0,95) e Stramonita haemastoma (μ3 = 1,15), bem como as médias para o lábio interno também foram respectivamente menores em N. virginea (μ1 = 0.66), seguida de T. viridula (μ2 = 1.97) e S. haemastoma (μ3 = 4.40). Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 332 G. X. SANTANA ET AL. Figura 5. Cicatrizes nas conchas predadas por Menippe nodifrons através das técnicas de esmagamento (crushing) e descascamento (peeling): (A, B, C, D) Stramonita haemastoma; (E, F) Tegula viridula; (G, H) Neritina virginea. Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 333 Comportamento predatório Ex situ do caranguejo Menippe nodifrons sobre Moluscos Gastrópodes Quadro I. Espessuras do lábio interno e externo em conchas de Neritina virginea, Tegula viridula e Stramonita haemastoma. Presas Lábio interno Lábio externo Média Erro Padrão N Média Erro Padrão N Neritina virginea 0,66 0,02 20 0,22 0,02 20 Tegula viridula 1,97 0,07 20 0,95 0,04 20 Stramonita haemastoma 4,40 0,18 20 1,15 0,08 20 As médias da espessura do lábio externo diferiu estatisticamente entre as três espécies de presas (ANOVA, F = 79.90, gl = 2, p = 0.000) rejeitando-se a hipótese nula (H0). O teste de Tukey mostrou as médias significativamente diferentes (HSD0.05 = 0.19 e HSD0.01 = 0.24) conforme a Tabela I. Tabela I. Teste de Tukey HSD para comparação múltipla entre as médias do lábio externo das presas: Neritina virginea, Tegula viridula e Stramonita haemastoma. Médias μ2 μ3 μ1 p < 0.01 p < 0.01 μ2 p < 0.05 Análise biomecânica das quelas. As quelas de Menippe nodifrons são dimórficas e apresentam dentições distintas em suas superfícies internas dos dedos fixos (própodo) e dos dátilos (dedo móvel). Na base do dedo fixo da quela maior é observado um tubérculo bastante proeminente em forma de molar, o qual é chamado de dente molariforme, seguido de outros tubérculos menores não pontiagudos. A superfície interna do dátilo (dedo móvel) também apresenta tubérculos menores e menos proeminentes do que aqueles encontrados no dedo fixo da quela maior (própodo). A quela menor apresenta dentições em forma de serra, tanto na parte interna do dátilo, como na superfície basal do dedo fixo. Os dentes são pequenos e pontiagudos. Nas quelas menores não se formam tubérculos em forma de molar como nas quelas maiores. M. nodifrons também apresentou diferenças no valor da vantagem mecânica (VM) calculado para as duas quelas (Tabela II). Os resultados, considerando-se o total entre machos e fêmeas da espécie, foi de VM = 0,38 para a quela maior (QM) e VM = 0,32 para a quela menor (Qm). Dessa forma, o valor numérico da vantagem mecânica das quelas de M. nodifrons são maiores que 0,3 caracterizando-os como especialistas em quebra de conchas duras e resistentes. Tabela II. Valores mínimos da vantagem mecânica (L1/L2; onde L1 = segmento do eixo fixo ao ponto de inserção no tendão do músculo maior; L2 = segmento do eixo fixo a ponta do dátilo) das duas quelas do caranguejo Menippe nodifrons. QM = quela maior; Qm = quela menor Vantagem mecânica QM Qm Machos 0,41 0,33 Fêmeas 0,36 0,31 Média VM 0,38 0,32 A Tabela III mostra a relação das características morfológicas das quelas de M. nodifrons e suas respectivas vantagens mecânicas. As técnicas de manipulação descritas anteriormente caracterizam a ação das quelas sobre as conchas dos moluscos predados. Tabela III. Características morfológicas e biomecânicas das quelas do caranguejo Menippe nodifrons. Morfologia dos dentes Tipo de quela Vantagem mecânica Quela maior (QM) Molariformes Esmagadora 0,38 Quela menor (Qm) Pontiagudos Cortadora 0,32 Discussão Preferência alimentar. No presente estudo o caranguejo M. nodifrons mostrou ter uma Ação sobre conchas de moluscos Esmagamento “crushing” Corte “peeling” preferência maior por Neritina virginea nos experimentos realizados, em relação às outras duas presas oferecidas Stramonita haemastoma e Tegula Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 334 viridula. A ocorrência desse comportamento, provavelmente, está relacionada ao fato de N. virginea possuir características morfológicas, como espessura da concha mais fina (ver Tabela 2) e lisa (sem ornamentações espinhosas), que a tornam mais susceptível e vulnerável ao caranguejo quando comparada a S. haemastoma e T. viridula. Estes dois gastrópodes possuem um lábio externo mais espesso, concha mais dura e ornamentada com pequenos espinhos. A concha de S. haemastoma possui uma espira mais alta do que a concha de Tegula viridula, essa característica pode aumentar a vulnerabilidade do molusco ao ataque pelo caranguejo, conforme foi observado na preferência maior de M. nodifrons por S. haemastoma em relação a T. viridula. Outra característica favorável ao menor ataque do caranguejo sobre T. viridula em relação a S. haemastoma, se dá pela presença de uma abertura menor da concha naquela, dificultando a manipulação das partes viscerais do molusco pelo predador. Turra et al. (2005) estudaram o comportamento predatório do caranguejo Menippe nodifrons sobre os gastrópodes S. haemastoma e Tegula viridula, e verificaram que esse caranguejo predava mais ativamente sobre S. haemastoma do que em T. viridula, essas observações estão de acordo com os resultados observados no presente estudo. A seleção do tamanho da presa é um importante componente no processo pelo qual as comunidades são estruturadas através da predação (Sammerson & Perteson 1984; Hines et al. 1990). Alguns estudos sobre predação de moluscos por caranguejos têm mostrado que existe uma preferência, destes últimos, por presas de tamanhos menores ou intermediários, em relação às presas de tamanhos maiores (Sanches-Salazar et al. 1987; Coombes & Seed 1992; Juanes & Hartwick 1990; Juanes 1992; Brown & Haihgt 1992). Existem fatores que possuem importante papel na seleção da presa por caranguejos entre os quais, pode-se citar a relação entre tamanho do caranguejo e da presa, nível de saciedade, dentição, abertura e força da quela e tempo de manipulação da presa (Yamada & Boulding 1998). Sih (1987) reporta que muitos predadores evitam atacar presas que dificultam claramente a captura, manipulação ou ingestão através dos mais variados mecanismos de defesas. Diversas características da morfologia, como espessura, ornamentação e diminuição da abertura das conchas de gastrópodes têm sido relatadas como responsáveis por reduzir diretamente a vulnerabilidade dos moluscos ao ataque de seus G. X. SANTANA ET AL. predadores, como, por exemplo, caranguejos moluscívoros. Entre os machos de M. nodifrons houve uma preferência maior por N. virginea em relação às espécies S. haemastoma e T. viridula. Em contraposição, as observações realizadas com fêmeas não foram estatisticamente significantes o suficiente para apontar alguma preferência por uma das presas. Esse comportamento entre machos pode ter como possível causa, o fato deles evitarem danificar suas quelas atacando uma presa mais fácil de ter a concha quebrada, pois, caso contrário, as quelas poderiam perder sua funcionalidade em outras atividades importantes na vida desses animais como, por exemplo, a reprodução (Juanes & Hartwick 1990; Juanes 1992). Muitos crustáceos decápodos evitam o risco de danificarem suas quelas durante a predação de moluscos de conchas mais resistentes escolhendo presas de tamanhos menores (Juanes 1992). Para Lee (1995), do ponto de vista evolutivo, a importância funcional das quelas nos decápodos (principalmente os braquiúros), é regida por três grandes forças seletivas: comportamento alimentar, interações competitivas e hábitos reprodutivos. Juanes (1992) observa que para a maioria dos crustáceos decápodos, principalmente entre os braquiúros, a danificação parcial ou total das quelas pode vir a ter um efeito ecológico de alta importância ao longo da vida desses animais. Esses efeitos implicam em mudanças nos hábitos alimentares, no comportamento predatório, no crescimento, nas trocas do exoesqueleto (ecdises), na regeneração de partes perdidas, nas taxas de mortalidade e no sucesso reprodutivo (Davis et al. 1978; Savage & Sullivan 1978; Sekkelsten 1988; Juanes & Hartwick 1990). Estudos prévios corroboram o fato de que caranguejos moluscívoros preferem se alimentar de presas menores e que ofereçam menos riscos de danos às quelas, principalmente no caso dos machos, onde a mesma é usada no processo copulatório (Davidson 1986; Juanes & Hartwick 1990; Juanes 1992; Brown & Haight 1992; Richardson & Brown 1992; Vermeij 1995; Brousseau et al. 2001; Smallegange & Van Der Meer 2003). O tempo de manipulação foi menor na espécie N. virginea quando comparado às duas outras espécies de moluscos, sendo essa, aliado ao tamanho e morfologia da concha, uma das prováveis razões da preferência de M. nodifrons por N. virginea. A frágil concha de N. virginea permitiu que o caranguejo fizesse uso do “crushing” para expor seus tecidos, o qual é uma técnica mais rápida do que o descascamento, usado para predar conchas Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 Comportamento predatório Ex situ do caranguejo Menippe nodifrons sobre Moluscos Gastrópodes mais resistentes como as de S. haemastoma e T. viridula. De acordo com Davidson (1986) em seus estudos sobre o comportamento predatório do caranguejo Ovalipes catharus sobre moluscos, a variação no tempo de predação ocorreu quando os caranguejos empregaram, para abrir as conchas, técnicas diferentes que dependiam, sobretudo, do tamanho da presa, da resistência da concha e provavelmente da vulnerabilidade da presa. De acordo com os estudos realizados por Brown & Haight (1992) sobre aspectos predatórios do caranguejo Menippe adina o handling time dos caranguejos sobre S. haemastoma e Crassostrea virginica aumentou com o tamanho da presa. Esse aumento no tempo de predação, provavelmente, ocorreu devido às técnicas de “crushing” e “peeling” utilizadas nos diferentes tamanhos de presas oferecidas; os caranguejos levam mais tempo para manipular as presas quando o “peeling” é utilizado no lugar do “crushing”. Lawton & Hughes (1985) reportam que o método de descascamento para quebrar conchas de paredes espessas em gastrópodes aumenta substancialmente com o tamanho da concha. Para M. nodifrons as observações encontradas estão de acordo com os estudos citados acima e também conforme os relatados para o caranguejo Ovalipes catharus (Davidson 1986) e para a espécie de siri azul Callinectes sapidus (Seed & Hughes 1997). Manipulação das presas e Análise Biomecânica das quelas. O caranguejo Menippe nodifrons manipulou as presas usando principalmente as técnicas de esmagamento e descascamento. O “crushing” (Zisper & Vermeij 1978; Palmer 1979) ou esmagamento foi uma técnica de ataque mais eficiente e mais rápida para quebrar as conchas. Enquanto que o “peeling” (Palmer 1979) técnica que consistia em raspar e cortar foi utilizada quando os caranguejos tinham dificuldades maiores em quebrar as conchas. Esta última técnica foi predominante em conchas de Stramonita haemastoma e Tegula viridula. O uso desta técnica pelos caranguejos pode ter uma relação direta com as características morfológicas das conchas desses gastrópodes, pois quando os caranguejos utilizaram esse método o tempo de manipulação aumentou e as dificuldades de manipulação eram maiores. A técnica de esmagamento ou “crushing” foi predominante em Neritina virginea. Esse fato por ter implicação na maior vulnerabilidade desse gastrópode diante da eficiência de M. nodifrons em capturá-la e consumíla. Bertness & Cunnigham (1981) estudando os 335 métodos de predação dos caranguejos moluscívoros Eriphia squamata e Ozius verreauxii mostraram que entre as duas espécies de caranguejos os métodos de predação foram similares, com o “crushing” sendo usado pelos caranguejos de forma bem sucedida sobre conchas de tamanhos relativamente menores, e o “peeling” em conchas de tamanhos maiores ou valores próximos ao tamanho crítico da presa. O descascamento é uma tática de predação usualmente mais comum quando as presas são mais resistentes ao esmagamento (Du Preez 1984; Seed & Hunghes 1995). Para Menippe nodifrons as técnicas e métodos empregados sobre as três espécies de presas são similares aos encontrados para outras espécies de braquiúros (Berteness & Cunningham 1981; Boulding 1984; Davidson 1986). As características morfológicas das quelas do caranguejo Menippe nodifrons são muito similares às observações realizadas para as quelas dos caranguejos da família Xanthidae (Vermeij, 1995) e dos gêneros Eriphia e Ozius (Bertness e Cunningham 1981; Seed e Hughes 1995) e principalmente com as quelas de Menippe mercenaria e Menippe adina (Lindberg & Marshall 1984; Brown & Haight 1992). As quelas de M. nodifrons são biomecanicamente especializadas para quebrar moluscos de conchas duras e resistentes, essas características estão conforme estudos realizados para a morfologia das quelas de decápodos (Yamada & Boulding 1998). Nesse estudo, o caranguejo Menippe nodifrons apresentou vantagem mecânica das duas quelas acima de 0,3 (V.A. = 0,38 para quela maior e V.A. = 0,32 para a quela menor). Além disso, M. nodifrons possui duas quelas dimórficas que apresentam características distintas quanto a função em quebrar as conchas de moluscos. A quela maior possui características de estruturas fortes e dentições molariformes usadas para esmagar as conchas, já as quelas menores são estruturas mais delicadas, com dentes em forma de serra especializadas em raspagem, corte e captura da presa. Essas características estão de acordo com observações realizadas por Seed & Hughes (1995, 1997), para estudos descritos sobre a morfologia das quelas em algumas famílias de caranguejos moluscívoros (Parthenopidae, Xanthidae, Grapsidae, Calappidae, Cancridae e Portunidae). Tamanho Crítico das presas e Espessuras das conchas. O tamanho crítico das presas Neritina virginea, Stramonita haemastoma e Tegula viridula pode ter influenciado na escolha da presa preferida e na técnica de manipulação observada para cada uma delas. Neritina virginea foi a presa com menor tamanho crítico e também a Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 336 única a ter a concha quebrada por “crushing”. Para as outras duas espécies de presas, em S. haemastoma o tamanho crítico foi menor do que em Tegula viridula. Nessas duas presas os caranguejos manipularam muito mais vezes através de “peeling” do que por “crushing”. Esse fato pode ter relação com as características das conchas desses gastrópodes e também pode ser efeito da limitação mecânica das quelas imposta pelo tamanho crítico das presas. Smallegange & Van Der Meer (2003) reportaram que o tamanho crítico em caranguejos da espécie Carcinus maenas tem influência não só na escolha do tamanho de suas presas, como também nas técnicas utilizadas. Ou seja, eles observaram que os caranguejos mudavam de técnica quando o tamanho da presa apresentava um valor (tamanho crítico da presa), no qual a largura dos moluscos forçou os caranguejos a trocarem o método de “crushing” pelo de “peeling”. 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Journal of Experimental Marine Biology and Ecology. 220: 191-211. Zar, J. H., 1999. Biostatistical analysis. Prentice Hall, Englewood Cliffs, NJ. Zisper, E.; Vermeij, G. J. , 1978. Crushing Behaviour of tropical and temperate crabs. Journal of Experimental Marine Biology and Ecology. 31: 155-172. Received September 2008 Accepted November 2008 Published online August 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 326-338 Aspectos fitosanitarios de los manglares del Urabá Antioqueño, Caribe colombiano ANA SOLEDAD SÁNCHEZ-ALFÉREZ1, RICARDO ÁLVAREZ-LEÓN2, SONIA GODOY BUENO CARVALHO LÓPEZ 3 & OLGA PATRICIA PINZÓN-FLORIÁN4 1 Corpourabá. Turbo (Antioquia). Colombia.Email: anasol54@hotmail.com Fundación Maguaré. Manizales (Caldas). Colombia.Email: alvarez_leon@hotmail.com 3 Univ. de Sao Pablo. Sao Pablo (Brasil).Email: sonialopes@ups.br 4 Univ. Distrital Francisco José de Caldas. Bogotá D. C. (Colombia).Email: opatriciap@udistrital.edu.co 2 Resumen. Se presenta una síntesis del estado del conocimiento de la presencia de Agrobacterium sp. y Neoteredo reynei asociados a diferentes estructuras de los manglares del Urabá antioqueño en la costa Caribe de Colombia. Palabras clave: manglares, moluscos teredos, bacterias, impactos, Caribe, Colombia Abstract. Phytosanitary aspects of the mangroves the Urabá Antioqueño, Colombian Caribbean. A synthesis of the state of the knowledge of the presence of Agrobacterium sp. is presented. and Neoteredo reynei associated to different structures of the mangroves of the Uraba antioqueño in the coast Caribbean of Colombia. Key words: mangroves, shipworms molluscs, bacterias, impacts, Caribbean, Colombia Introducción En el desarrollo de las actividades realizadas para la elaboración del Diagnóstico de los Manglares del Caribe Colombiano, objetivo de la primera fase del Proyecto PD 171/91 Rev 2 Fase I, se logró el reconocimiento de los manglares desde Cabo Tiburón en el Urabá chocoano hasta Castilletes en el Departamento de la Guajira, identificando tanto los aspectos técnicos generales de éste ecosistema, como las entidades y comunidades relacionadas. Los manglares del Golfo de Urabá están siendo afectados por diversos problemas fitosanitarios, causando el deterioro del bosque y en consecuencia afectando a las comunidades que hacen uso de sus productos. El reconocimiento indicó que dentro de los problemas encontrados el de mayor incidencia es la presencia de un barrenador de raíces y tronco, que afecta el mangle rojo o canillón (Rhizophora mangle), no obstante, adicionales reconocimientos comprobaron el ataque en árboles del mangle blanco o bobo (Laguncularia racemosa). Mediante las observaciones preliminares y la consulta de información sobre el tema, se logró determinar que el agente causante es un molusco teredínido Neoteredo reynei (Sánchez-Alférez & Álvarez-León, 2000), que afecta, en especial, a R. mangle, y en menor proporción a L. racemosa, ascendiendo por las raíces, hasta perforar el fuste logrando en algunos casos debilitar la estructura provocando el volcamiento. La mayoría de investigaciones en el país, se centran en los daños que se presentan por ataque de moluscos, entre ellos el teredo, en árboles, muertos o apeados, del Pacífico y en menor porcentaje en el Caribe. La revisión se amplió al campo internacional, encontrándose registros de ataque de teredo en árboles vivos en los manglares de Brasil, la Florida y en la costa de Kerala (Arabia), información que sirvió de base para proponer el estudio realizado por el Proyecto Manglares de Colombia y la Corporación para el Desarrollo Sostenible de Urabá (CORPOURABA), con el objeto de conocer mas de cerca la problemática fitosanitaria de los manglares del Golfo y plantear alternativas para nuevas investigaciones. Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 340 Antecedentes. La presencia del barrenador fue detectada por el Proyecto Manglares de Colombia, en sus diferentes recorridos, en las bocas del río Atrato en el Urabá antioqueño, mas exactamente en las Bahías de El Roto, Tarena, Hierbazal, y Marirrio, al igual que en la Ensenada de Rionegro. Adicionalmente en otros Departamentos como en Sucre: Ciénaga de la Caimanera, Guacamayas y Bahía de Barbacoas, en Bolívar: Bahía de Cartagena. Finalmente y de acuerdo con los campesinos de la zona, se puede también encontrar en los manglares de la Bahía de Cispatá (Córdoba). De acuerdo con Turner (1966), algunos organismos marinos pueden causar, al menos en una de las etapas de su ciclo de vida, deterioro (erosión, descomposición, transformación) de los sustratos donde habitan. Se conocen como biodeterioradores y pueden colonizar sustratos orgánicos o inorgánicos. Sandoval et al. (1995) indican que los principales sustratos orgánicos donde habitan los biodeterioradores son las maderas, principalmente troncos y raíces muertas de mangle u otras especies vegetales. Los moluscos bivalvos que actúan como biodeterioradores de madera son ampliamente conocidos como plagas de muelles, pilotes y otras estructuras civiles construidas en madera (Turner, 1984). Los primeros registros sobre teredos en Colombia datan de agosto de 1499, en los relatos que Américo Vespucio realizó sobre algunos sitios de la Guajira, “vale la pena recordar esos nombres que dicho navegante dio a los accidentes geográficos que encontró durante el recorrido por la costa, a saber: Cabo de la Esperanza (tal vez Punta Espada en la Guajira); almadraba, que es un lugar para la pesca de atunes; lago, lugar de aguas tranquilas que bien puede ser la Bahía de Portete o Bahía Honda; aguada, donde por causa de la broma o teredo, el terrible gusano destructor de la madera de las embarcaciones, las carabelas hicieron agua...” (Anónimo, 1996). En general en Colombia, la mayoría de registros de teredos como biodeterioradores de madera han sido realizados en el Pacífico, teniendo en cuenta el daño económico que ha representado al sector maderero de la zona. Jaime R. Cantera, Biólogo docente de la Universidad del Valle ha sido uno de los pocos estudiosos de éstos bivalvos a nivel nacional, sin haber llegado a mencionar en sus publicaciones el ataque de teredo en las raíces superiores o fustes de árboles de mangle en pie, aspecto que ha llamado la atención de los conocedores del manglar y que ha sido la principal razón por la cual, la Corporación Autónoma Regional de Urabá CORPOURABA y el Proyecto A. S. SANCHEZ-ALFEREZ ET AL. Manglares de Colombia (MMA / OIMT), decidieran realizar el primer acercamiento al conocimiento sobre la incidencia del teredo como hospedero en raíces y troncos de los manglares en pie en el Urabá antioqueño. El objetivo general del trabajo se centro en la realización de un muestreo en los manglares de Urabá, para obtener información sobre la incidencia del ataque del teredo y proponer con mayor conocimiento trabajos puntuales que aseguren el manejo fitosanitario de los manglares a nivel nacional. Para el cumplimiento de dicho objetivo, se plantearon los siguientes objetivos específicos: (1) Realizar una adecuada identificación del teredo que ataca individuos vivos de mangle en Urabá. (2) Determinar si las agallas observadas en los manglares de Urabá, están relacionadas con el ataque del teredo. (3) Determinar las zonas con mayor presencia de teredo en las bocas del río Atrato, plantear hipótesis sobre los posibles factores que inciden o favorecen su presencia. (4) Determinar la incidencia y severidad del ataque de teredo en las zonas muestreadas. (5) Recomendar acciones para el mayor conocimiento de los problemas fitosanitarios detectados y su posible control. (6) Dar las pautas generales para la continuidad de los estudios e investigaciones en favor de mejorar las condiciones sanitarias de los manglares, como contribución a las Corporaciones Autónomas Regionales (CAR’s) para iniciar sus programas de manejo. Materiales y Metodos Se planteó la aplicación de una estrategia de intervención ágil que asegurara la optimización de los recursos tiempo y presupuesto, procurando obtener información mediante la cual se lograran los objetivos planteados. Inicialmente se pretendió la adecuación de metodologías de muestreo diseñadas para estudios fitosanitarios en plantación, pero se descartaron, teniendo en cuenta que la toma de datos por observación y medición de parámetros estructurales no eran suficientes para lograr la información requerida, por lo tanto se planteó una metodología, que además de incluir la toma de información de estructura para el conocimiento del bosque, mediante el apeo de árboles precisara las variables severidad e intensidad del ataque. La metodología planteada se aplicó en los manglares de las bocas del río Atrato y en la Ensenada de Rionegro. Inicialmente sobre cartografía reciente se definieron unas zonas preliminares de trabajo, las cuales se replantearon con la revisión física en campo, de acuerdo con la incidencia observable del ataque. Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 Aspectos fitosanitarios de los manglares del Urabá Antioqueño, Caribe colombiano Diseño del muestreo. Con base en los trabajos realizados para manglares, incluyendo el diagnóstico efectuado por el Proyecto Manglares de Colombia, el muestreo se realizó mediante el levantamiento de líneas base, perpendiculares a la 341 línea de costa en las cuales se ubicaron dos parcelas para toma de información con un área individual aproximada de 25 m2 cada una y distanciadas entre si aproximadamente 80 m. La parcela número 1 se ubicó lo más cerca posible de la línea de costa. Figura 1. Ubicación de la zona de muestreo en el Golfo de Urabá (Colombia). (1) Bocas del Atrato, (2) Ensenada de Rionegro; con la localización de las parcelas establecidas. En la línea base se levantó un perfil de vegetación, en cada parcela de muestreo se realizaron las correspondientes mediciones para evaluar los parámetros estructurales, en especial para el estado de latizal y fustal y se incluyó el muestreo de la regeneración natural, adaptando los conceptos de Falla (1970) en: fustales (diámetro superior a 15 cm), latizales (diámetro entre 5 y 15 cm) y brinzales establecidos (diámetro entre 2,5 y 5 cm). Para la regeneración natural se realizó el muestreo dentro de la misma parcela de 25 m2 un área de 1m2, seleccionada al azar. En la parcela de 25 m2, se midieron el total de fustales, latizales y brinzales establecidos. Además de los parámetros estructurales se realizaron las mediciones sobre el ataque del teredo. Daño causado por Neoteredo reynei. Para el análisis de ésta información, se realizó el apeo de tres árboles, tomados al azar dentro de la parcela. En cada árbol, se contabilizó el número total de raíces incluyendo la base del tronco o raíz principal. El fuste del árbol apeado y con el ataque visible del barrenador, se cortó en secciones de un metro y en cada una de ellas se cuantificó el área afectada, mediante el conteo de galerías, así como el porcentaje del área afectada con base en el total del corte, de igual forma se evaluó el daño en las raíces. En cada estructura (raíz o fuste) cortada se realizó la observación sobre la presencia o no del teredo, con base en la obtención de éste, ya fuera completo o por partes, esto teniendo en cuenta que los cortes fueron realizados con motosierra, la cual seccionaba el animal de encontrarse en la galería cortada. Variables analizadas. (1) Número de árboles afectados en cualquiera de sus estructuras (raíces o fuste) con relación al cien por ciento de los individuos de la parcela. (2) Número de raíces atacadas por árbol y promedios por parcela y por línea, esto con base en el porcentaje del área afectada y en el número de galerías, con la misma salvedad en el caso de galerías múltiples. (3) Número de fustes atacados y altura de presencia de galerías, tomada a partir de la altura de la última raíz. (4) Área del daño, se evaluó con relación al cien por ciento del área total de la sección cortada, diferenciando entre raíces y fuste y se domina en los resultados como grado de afectación. (5) Número de galerías, en cada una de las estructuras cortadas, raíces y fuste, se contabilizó el número de galerías Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 342 A. S. SANCHEZ-ALFEREZ ET AL. presentes. En algunos casos, el conteo no fue posible, debido al alto grado de deterioro a causa del ataque, para éste caso se incluyó en el cuadro de toma de información el resultado de número de galerías con la letra “M” de múltiples, para efecto del análisis, no se tuvo en cuenta la letra M realizando la correspondiente aclaración. (6) Presencia o no del teredo, ésta variable se consideró si se observaba el animal ya fuera entero o cortado. Metodologia para analizar las agallas. En el campo dentro de un bosque localizado en Apartado (Ant.) se tomaron muestras de agallas de varios tamaños tratando de incluir lesiones jóvenes y adultas, las cuales fueron analizadas en el laboratorio de Sanidad Forestal de la Universidad Distrital “Francisco José de Caldas”. En el laboratorio se hicieron observaciones macro y micrsocópicas buscando la presencia de signos del posible agente causal. Así mismo de hicieron siembras en medios semisólidos específicos para Agrobacterium. El cubrimiento del trabajo se extendió en las bocas del río Atrato, desde la Bahía de Marirrio al sur de las mismas bocas, hasta Boca Tarena, pasando por las Bahías de la Paila, la Burrera y Matuntugo, al igual que en la Ensenada de Rionegro. Las observaciones sin aplicación de la metodología se realizaron al sur de Turbo en los bosques de manglar de la boca del río Currulao, preservados por la influencia de grupos al margen de la ley. De las ocho líneas establecidas, seis se ubicaron en las bocas del Río Atrato y dos en la Ensenada de Rionegro. En el Atrato se procuró una distribución uniforme hacia el norte y sur cubriendo una extensa zona distribuida en cuatro (4) líneas hacia el sur de Bocas del Atrato o Turbito así: la línea número 1 en el Brazo La Burrera, las líneas 2 y 3 en la Bahía de Marirrio y la línea 4 en la Bahía la Paila. Hacia el norte se establecieron la línea 7 en el Caño Matuntugo y la línea 8 en Boca Tarena. (Figura 2) Metodología para analizar el molusco. Se tomaron muestras de N. reynei y se enviaron a la Universidad de Sao Pablo en Brasil, en donde se realizó la correspondiente identificación además de algunos análisis adicionales sobre la estructura interna del molusco. Se tomaron seis N. reynei de diferentes tamaños, obtenidos con extrema dificultad, teniendo en cuenta que el molusco expande su cuerpo ocupando la galería y al menor corte o pinchazo vacía los líquidos contenidos en su estructura y por lo tanto reduciendo el diámetro con el inminente peligro de cortarlo al mínimo tirón, igualmente no fue posible obtener un animal halando alguno de sus extremos ya que presenta resistencia y a la menor presión se rompe. Metodología para determinar la salinidad y la temperatura. Para determinar los niveles de salinidad y de temperatura del agua dentro y fuera de las parcelas, se utilizo un refractómetro de campo y un termómetro de cubeta, los cuales permitieron conocer las variaciones de estos parámetros durante el periodo de observación. Resultados Generales. Se logró la aplicación de la metodología en ocho líneas de muestreo completas incluyendo el levantamiento de información en las respectivas 16 parcelas. Adicionalmente se realizaron observaciones en algunos sitios de los cuales se obtuvo información sin aplicar la metodología, debido a las condiciones externas de sanidad de los árboles. Línea de Costa Figura 2. Diagrama de las parcelas establecidas y monitoreadas, en el bajo río Atrato (Caribe colombiano). Las 16 parcelas cubrieron un área total de 400 m , distribuida uniformemente tanto a la orilla de manglar, sobre el cuerpo de agua, como a 80 metros hacia el interior del mismo. En total en el área de parcela se inventariaron 57 árboles en los tres estados de crecimiento dados: fustal, latizal y brinzal establecido. La altura promedio en las parcelas vario entre 6.1 m en la parcela 2 de la línea La Burrera y 20 m en las parcelas 2 de las líneas La Paila, Matuntugo y Rionegro II. Dichos promedios se ven disminuidos en las parcelas 2 debido a la mayor presencia de las categorías latizo y brinzal establecido. De los 57 árboles totales el 96 % correspondió a R. mangle y 4% a L. racemosa. De estos 57 árboles se evaluaron mediante la aplicación de la metodología de apeo y corte de raíces un total Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 2 Aspectos fitosanitarios de los manglares del Urabá Antioqueño, Caribe colombiano de 37 árboles, correspondiendo al 65 % del total de la población encontrada en el área muestreo. De los 37 árboles evaluados, 11 (29.7%) se encontraron afectados a nivel de los fustes, con un grado de afectación o daño en promedio del 18.2%, lo que correspondió a un promedio de 3.5 galerías por árbol. Se detecto un caso de galería múltiple en la parcela 1 de la línea 3 Marirrio (árbol 2). El 54% (20 árboles) de los árboles evaluados, se encontraron afectados a nivel de raíz. De las 349 raíces cortadas, estaban infectadas 39 (11%). El grado de afectación en promedio es del 20%, en las raíces infectadas con un promedio de 2.7 galerías. Cabe destacar que en dos raíces se encontraron galerías múltiples (Marrirrio I y II parcela 1 árboles 3 y 2 respectivamente).< Se detectó la presencia de siete N. reynei en seis árboles, lo cual equivale al 16,2 % del total de árboles evaluados (37), encontrando un teredo en las raíces y seis a nivel de fuste. Resultados a nivel de líneas de muestreo. Comparando los resultados entre las ocho líneas de muestreo se encontró que las líneas que presentaron mayor cantidad de árboles afectados a nivel de raíces fueron: Marirrío 1 con seis y Marirrío 2 con cinco, lo que corresponde respectivamente al 30 y 25 % del total de los árboles afectados a nivel de raíces; el menor resultado se encontró en La Paila con cero árboles afectados. Con relación al daño a nivel de raíces se encontró que las líneas con mayor cantidad de raíces afectadas fueron Marirrio II, con 15 y Marirrio I con 14 y la de menor fue la Paila con cero raíces afectadas, correspondiendo respectivamente al 38,5, al 35,9 y al 0 % del total de las raíces afectadas. El mayor grado promedio de afectación correspondiente al porcentaje de área afectada en la sección del corte, se presentó en las líneas Rionegro I y II con el 50% de afectación para cada una y el menor se obtuvo en la Línea 4 La Paila, con 0%. La línea con mayor promedio de galerías encontradas fue Marirrio 2 con 6,2 galerías, y la de menor promedio fue La Paila con cero galerías; cabe destacar que en las líneas Marirrio 1 y 2, se encontró una raíz en cada línea con galería múltiple. La evaluación de daño a nivel de fuste, indicó que la mayor cantidad de fustes afectados se encontraron en las líneas Marirrio 1 y 2 con 4 fustes cada una, correspondiendo al 72,8 % del total y las menores fueron Rionegro I y II, y Boca Tarena con cero. La línea la Burrera presento el mayor grado promedio de afectación con un 30%. La mayor cantidad de galerías promedio se encontró en la línea Marirrio II con 5 galerías, destacando que un fuste de la línea Marirrio II presento galerías múltiples. 343 La mayor presencia de N. reynei ocurrió en la línea Marirrio 2 con cuatro ejemplares, lo cual equivale al 57% del total; seguida por la línea Marirrio 1 con dos ejemplares, lo que equivale al 28,6% del total y por último la línea la Burrera con un ejemplar, lo cual corresponde al 14,4 % de la presencia total de teredos. Relación entre las parcelas y la distancia de la costa. La mayor cantidad de árboles se evaluaron en la Parcela 1, con un total de 22 árboles o 59,4%, el restante 46 % (15 árboles) se ubicó en la Parcela 2. La mayor cantidad de raíces afectadas se encontró en las parcelas ubicadas a 80 m de la costa, con un porcentaje del 51.3 % en relación con el total de raíces afectadas. El mayor grado promedio de afectación, ocurrió en las Parcelas 1, al igual que el mayor número promedio de galerías con un 41,1% y 3 galerías respectivamente; cabe anotar que dos raíces presentaron galerías múltiples. El análisis de los fustes indicó que las parcelas ubicadas a cero metros de la costa presentaron la mayor número promedio de fustes afectados, con un total de 7 o 63,7% del total. El mayor grado de afectación promedio se encontró en las parcelas ubicadas a cero metros de la costa con 24,6%, al igual que el mayor promedio de galerías con 4,8; destacándose que un fuste presento galería múltiple. Se encontraron cuatro N. reynei en las parcelas ubicadas a 0 m y 3 ejemplares en las parcelas ubicadas a 80 m de la costa. Los análisis micro y macroscópico de las agallas no mostraron signos de hongos, bacterias o nemátodos. En los cultivos en medios semisólidos no se pudo aislar Agrobacterium sp. Salinidad y temperatura. En la Tabla I, se relacionan los parámetros obtenidos dentro del área de la parcela de muestreo. Discusión De acuerdo con los objetivos planteados se resalta el hecho de haber logrado la primera clasificación del agente causal de los daños a los manglares del Urabá Antioqueño, reportes que hasta la fecha no había sido realizado y el cual nos acerca al conocimiento del comportamiento anormal del molusco ascendiendo en los árboles a niveles poco comunes para su especie. Aspecto interesante y el cual es objeto de mayores estudios que analicen los diversos factores que han propiciado el actual comportamiento. El resultado de los análisis numéricos ha indicado que la zona más afectada es la Bahía de Marirrio y en especial los árboles que se localizan Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 344 sobre la línea de costa o playa. Así mismo las zonas de menor observación y presencia del N. reynei se localizan al extremo norte o Boca Tarena. Un aspecto que llamó la atención fue no haber detectado en el estudio la presencia del ataque en la ensenada de Rionegro, sitio en el cual las observaciones A. S. SANCHEZ-ALFEREZ ET AL. preliminares indicaron un alto índice de ataque, corroboradas por los pescadores, moradores permanentes del sector. Este resultado se atribuye tanto a la aleatoriedad del muestreo como a la premura del tiempo que impidió localizar con mayor exactitud todas las áreas afectadas. Tabla I. Salinidad y temperatura en las aguas adyacentes a las parcelas. P = Parcelas 1 y 2 Salinidad Temperatura (°C) Hora (ups) (H-M) Línea No. Zona P1 P2 P1 P2 P1 P2 T1 La Burrera 5 3 28 23 10:10 11:45 T2 Marirrio I 14 5 24 23 12:18 13:35 T3 Marirrio II 5 5 25 23 12:15 14:00 T4 Bahía Paila 5 0 26 26 13:40 14:00 T5 Rionegro I 15 15 28 20 11:30 12:25 T6 Rionegro II 14 12 26 26 13:45 14:35 T7 Matuntugo 3 2 27 27 13:40 14:10 T8 Boca Tarena 3 3 27 27 10:50 11:30 De acuerdo con información adicional compilada en el desarrollo del trabajo, las variables salinidad y temperatura, al parecer tienen poca incidencia con la presencia del ataque de teredo y menos con el hecho de que el animal logre ascender en los fustes llegando a alturas poco comunes en la especie. Las variables que al parecer tiene algún grado de incidencia podrían estar relacionadas con la descarga sedimentaria que se vierte al Golfo, al igual que los factores que inciden en la adhesión y cantidad de larvas del molusco. Además, N. reynei se adapta muy bien a vivir en las áreas de manglar poco influenciadas por las aguas marinas. La ocurrencia de N. reynei principalmente en las áreas internas de bosque del mangle y viviendo incluso en áreas degradadas de manglar han sido registrado por Lopes & Narchi (1993, 1997) en el mangle de Praia Dura (São Paulo) Brasil y por Rancurel (1971) en los mangles del río de Bandama (África). Los caracteres anatómicos de N. reynei descritos por Turner (1966), Rancurel (1971) y Lopes et al. (2000) sugieren que esta especie usa la madera como fuente principal de su alimentación, mientras sólo depende del plancton disponible, durante las pleamares. En líneas generales la incidencia del ataque a nivel de raíz es alta en relación al total de la muestra, teniendo en cuenta que de 37 árboles evaluados el 57 % se encontró afectado y en especial llama la atención que los cortes fueron en su totalidad aéreos, arriba de 30 cm sobre el nivel medio del suelo, indicando que el molusco, aunque normal su presencia en las raíces de R. mangle, si asciende anormalmente en la zona objeto de la evaluación. La incidencia a nivel de fuste se considera numéricamente baja, con un promedio de 29.7% con relación al total de fustes evaluados, aunque este porcentaje ecológica y económicamente puede considerarse alto, si se tiene en cuenta adicionalmente la calidad de los árboles afectados y los costos económicos de presentarse este ataque en bosques objeto de aprovechamiento. En cuanto a la severidad al nivel de raíces, el análisis numérico indica que de un total promedio de 9.5 raíces por árbol, 1,95 fueron atacadas, este resultado es bajo teniendo en cuenta que en cada una de éstas raíces el área promedio afectada fue del 20 %, lo que puede indicar un bajo porcentaje de inestabilidad del árbol si se consideran las fuerzas físicas que lo mantienen en pie. Aspecto por analizar mas detenidamente ya que estos resultados son generales, al particularizar se podría observar que el porcentaje de raíces afectadas se dio con mayor incidencia en los árboles ubicados en las parcelas número 1 o sea, a cero metros de la costa, sitios en los cuales se presenta por observación el mayor porcentaje de árboles caídos por efecto de la pérdida de estabilidad. La severidad de ataque al nivel de árbol es de 55% si se tiene en cuenta que de los 20 árboles afectados en las raíces en 11 ascendió el ataque al fuste. Lo que indica un alto grado de daño por árbol. Esto quiere decir que el árbol que logra ser objeto de ataque por teredo tiene una alta probabilidad de sufrir daños en sus estructuras. Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 Aspectos fitosanitarios de los manglares del Urabá Antioqueño, Caribe colombiano Un análisis detallado de otros parámetros tales como la salinidad y temperatura de los sitios de muestreo, indica una leve variación, poco representativa para el análisis en cuestión, aspecto que debe analizarse con mayor profundidad con base en los resultados hasta ahora obtenidos y con muestreos secuenciales en el tiempo para lograr determinar variación, ya que se considera que un dato puntual no es representativo. Estudio sobre agallas. En la realización del diagnóstico de los manglares en las bocas del Atrato, las observaciones generales indicaron inicialmente la presencia en los árboles de unas formaciones a modo de agallas en todas sus estructuras (fuste, ramas, raíces). Dichas formaciones se presentan como un afloramiento de la madera como si explotara y quisiera salir de la corteza, su consistencia es fuerte y no presenta ningún tipo de secreción. Desde el golfo las formaciones de mayor tamaño se asemejan a los nidos del comején y por tal razón se ha dicho que los manglares de Urabá, están siendo afectados por éstos insectos. Al detectar la presencia y ataque de los teredos, se consideró que dichas estructuras o afloramientos de la madera pueden ser también una respuesta visible a la presencia de teredo en las raíces del árbol, hipótesis que se pretendió comprobar con la realización de un muestreo paralelo al trabajo del teredo. Las observaciones macroscópicas en campo y laboratorio confirman la ocurrencia de agallas o tumores de los cuales no fue posible evidenciar estructuras de organismos patógenos. La sintomatología observada y la ausencia de signos de bacterias, hongos o nemátodos, indica que se trata de lesionas ocasionadas por Agrobacterium tumefasciens, patógeno comúnmente registrado en especies forestales y que causa esta sintomatología. La biología de este patógeno hace difícil su aislamiento a partir de lesiones desarrolladas, ya que se conoce que penetra principalmente por heridas e induce la formación del tumor alterando la información genética a nivel del núcleo de la célula sin que se requiera su presencia para la posterior proliferación del tejido. Otra forma de tratar de aislar Agrobacterium seria a partir de muestras de suelo circundante a los árboles afectados; en este caso sería a partir de muestras de suelo o acumulaciones superficiales de materia orgánica pero estos análisis no se realizaron. La bacteria penetra por heridas, principalmente, aunque algunas pueden hacerlo por aberturas naturales. Agrobacterium sp. es muy específico de heridas, así mismo es una bacteria 345 aerobia, por lo que se presume que el sitio de entrada debe corresponder inicialmente a zonas expuestas al aire, descartando el hecho de que el daño por teredos incida en favorecer la entrada de la bacteria, considerando que la larva del molusco normalmente penetra por la base de la raíz. La bacteria es aerobia, pero existe la inquietud de si el ataque ha podido iniciarse por las raíces cuando estas están expuestas debido a cambios en la altura de la marea Una vez éste es inducido, la bacteria no necesita estar allí para que siga produciendo el sobre-crecimiento. Esta es la razón por la cual solamente es posible aislarla de lesiones muy jóvenes. Viendo las agallas desde éste punto de vista, se puede concluir que no necesariamente existe relación entre el ataque del N. reynei y el Agrobacterium sp. Conclusiones En líneas generales se recomienda que los próximos estudios sobre el tema, se relacionen con la profundización del conocimiento sobre el N. reynei, y en especial con lo relacionado con el tipo de larva, los factores que inciden en su arraigo y las cantidades de las mismas en las aguas del Golfo, al igual que los predadores y condiciones que han generado cambios en su comportamiento. Así los resultados del presente estudio indiquen la sectorización del ataque en zonas con mayor vulnerabilidad, se recomienda profundizar el conocimiento del ataque con el animo de garantizar que el N. reynei no se especialice colonizando mayor cantidad de hospederos y por ende amplíe su radio de acción. El posible control del ataque debe estar relacionado con los resultados obtenidos sobre el conocimiento de la larva y su comportamiento. Es importante aclarar que adicionalmente a cualquier resultado de manejo y control de agentes destructores como el molusco bivalvo en cuestión, debe proyectarse el área del conocimiento de manglares hacia el ordenamiento y manejo silvicultural de los mismos garantizando de éste modo bosques de calidad genética, sanidad fitosanitaria y económicamente rentables. Agradecimentos. A la Universidad Distrital “Francisco José de Caldas” y a la Universidad Nacional de Colombia-Sede Bogotá, en Colombia y a la Universidad de São Pablo en Brasil, las cuales a través de sus investigadores y laboratorios aportaron valiosa información para los resultados de la presente contribución Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 346 Referencias Anónimo. 1996. Revista Credencial Historia. Edic. 82: 3-5. Falla-Ramírez, A. 1970. Definición de términos silviculturales. Proy. INDERENA / PNUD-FE / FAO / COL 14. Boletim Técnico, 3 (1): 120. Lopes, S. G. B. C. & Narchi, W. 1993. Levantamento e distribuição das espécies de Teredinidae (Mollusca, Bivalvia) no manguezal da Praia Dura, Ubatuba, São Paulo, Brasil. Boletim do Instituto Oceanográfico, 41: 29-38. Lopes, S. G. B. C. & Narchi, W. 1997. Recrutamento larval e crescimento de Teredinidae (Mollusca - Bivalvia) em região entremarés de manguezais. Revista Brasileira de Oceanografia, 45: 77-88. Lopes, S. G. B. C., Domaneschi, O., de Moraes, D. T., Morita, M. & Meserani, G. L. C. 2000. Functional anatomy of the digestive system of Neoteredo reynei (Bartsch, 1920) and Psiloteredo healdi (Bartsch, 1931) (Bivalvia: Teredinidae), pp. 257-271 In: Harper, E. M., J. D. Taylor & J. A. Crame (eds.) The Evolutionary Biology of the Bivalvia. The Geological Society of London. London (U. K.). A. S. SANCHEZ-ALFEREZ ET AL. Rancurel, P. 1971. Les Teredinidae (Mollusques Lamellibranches) dans les lagunes de Cóte d' Ivoire. Memóries of Recherche Science Techenologie Outre-Mer, 47: 1-235. Sánchez-Alférez, A. S. & Alvarez-León, R. 2000. First report of Neoteredo reynei (Bivalvia: Teredinidae) in the mangrove swamps of the Colombian Caribbean. UCR-Revista de Biologia Tropical, 48 (2/3): 720. Sandoval, F., Cantera-Kintz, J. R. & Bolívar, G. A. 1995. Bivalvos biodeterioradores de la madera en la Bahía de Buenaventura, Pacífico Colombiano. Tomo I pp. 214-244 In: CanteraKintz, J. R. & J. D. Restrepo-Angel (eds.) Delta Río San Juan, Bahías de Málaga y Buenaventura, Pacífico colombiano. Univ. EAFIT / Univ. del Valle / COLCIENCIAS. Medellín (Ant.) Colombia, 337 p. Turner, R. D. 1966. A survey and illustrated catalogue of the Teredinidae (Mollusca, Bivalvia). The Museum of Comparative Zoology, Harvard University. Cambridge (Mas.) USA, 262 p. Turner, R. D. 1984. An overview of research on marine borers: past progress and future direction, pp. 1-16 In: Marine biodeterioration, an interdisciplinary study. Annapolis (Maryland) USA. Received April 2009 Accepted July 2009 Published online September 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 339-346 Variação sazonal e mudanças ontogênicas na dieta de Menticirrhus americanus (Linnaeus, 1758) (Teleostei, Sciaenidae) na baía de Ubatuba-Enseada, Santa Catarina, Brasil CAROLINA F. HALUCH1, MATHEUS O. FREITAS2, MARCO F. M. CORRÊA3, VINÍCIUS ABILHOA2 1 Programa de Pós-graduação em Zoologia, Departamento de Zoologia, Universidade Federal do Paraná (UFPR), Centro Politécnico, CP 2936, 69083-000 Curitiba, PR, Brasil. Email: carolzinha_h20@hotmail.com 2 GPIc – Grupo de Pesquisas em Ictiofauna. Museu de História Natural Capão da Imbuia. Rua Prof. Benedito Conceição, 407, 82810-080, Curitiba, PR, Brasil. Email: serranidae@gmail.com, vabilhoa@uol.com.br 3 Centro de Estudos do Mar, Setor de Ciências da Terra, Universidade Federal do Paraná. Av. Beira Mar, s/n, 83255-000, Caixa Postal 50002, Pontal do Sul, PR, Brasil. Email: mfmcorrea@ufpr.br Abstract. Seasonal variation and ontogenetic shifts in the diet of Menticirrhus americanus (Linnaeus, 1758) (Teleostei, Sciaenidae) in Ubatuba-Enseada Bay, Santa Catarina, Brazil. Ontogenetic and seasonal changes in the diet of the southern kingfish Menticirrhus americanus sampled at Ubatuba-Enseada, Santa Catarina northern coast, were investigated. Trawl nets were used for the monthly surveys during October (2003) and September (2004). Stomachs of 137 individuals between 4.2 and 31.8 cm were analyzed. The species showed a carnivorous and benthic food habit, composed mainly by crustaceans, fishes and polychaetes. According to the similarity analyses, the use of food resources was influenced by seasonal and ontogenetic variations. Juveniles and adults share the same resources, but in different ways. Crustaceans showed higher representativeness in all the size-classes. Polychaetes were the most important items ingested by small individuals (up to 12.1 cm), decreasing this importance with M. americanus sexual maturity, when fishes were more important in the diet. Crustaceans were the most important items in spring and winter, substituted by fishes in summer. Hypothesis concerning diet shift and prey availability were discussed. Key words: coastal region, feeding, food habits, food items Resumo. Foram investigadas as variações ontogênica e sazonal na dieta da betara Menticirrhus americanus coletadas na baía de Ubatuba-Enseada, no litoral norte de Santa Catarina. Redes de arrasto com porta foram utilizadas para as coletas mensais, entre outubro de 2003 e setembro de 2004. Foram analisados 137 estômagos provenientes de indivíduos entre 4,2 e 31,8cm. O hábito alimentar da espécie é carnívoro e bentófago, composto principalmente por crustáceos, peixes e poliquetas. As análises de similaridade revelaram que o uso de recursos foi influenciado pelas variações sazonais e ontogênicas. Juvenis e adultos compartilharam os mesmos recursos, porém de formas diferentes. Em todas as classes de tamanho os crustáceos apresentaram alta representatividade. Poliquetas foram os itens mais importantes para os indivíduos pequenos (até 12,1cm), diminuindo sua importância com a chegada da maturidade sexual da betara, quando os peixes passam a adquirir elevada importância na dieta. Entre as estações do ano, os crustáceos foram importantes como itens alimentares na primavera e inverno, substituídos por peixes no verão. Hipóteses relativas a mudanças na dieta e a disponibilidade de presas são discutidas. Palavras chaves: alimentação, hábitos alimentares, região costeira, itens alimentares Introdução Menticirrhus americanus (Linnaeus, 1758) distribui-se desde Cape Cod (Estados Unidos) até Buenos Aires (Argentina) (Menezes & Figueiredo Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 348 C. F. HALUCH ET AL. 1980), e é conhecida popularmente como betara ou papa-terra, sendo encontrada sobre fundos arenosos e areno-lodosos em águas costeiras de pouca profundidade e em regiões estuarinas (Rondineli et al. 2007). Na ictiofauna registrada na baía de Ubatuba-Enseada em Santa Catarina, esta espécie apresenta grande freqüência nos arrastos de fundo, ocorrendo de forma abundante com outros representantes das famílias Sciaenidae, Paralichthyidae e Tetraodontidae (Freitas et al. 2005, Freitas et al. 2007). Os sciaenídeos são comumente citados como os principais componentes do bay-catch nas pescarias de arrasto direcionadas para o camarão sete-barbas, sendo que a abundância de M. americanus sugere que a mesma desempenha papel importante na dinâmica deste sistema (Coelho et al. 1986, Andrigueto-Filho 2002, Chaves et al. 2003). Apesar disto, e do fato que a partir dos estudos sobre a alimentação podem ser obtidas importantes informações para a administração dos recursos pesqueiros (Zavala-Camin 1996, Hahn et al. 1997), poucos estudos que abordam diretamente a dieta da espécie foram realizados. Os principais trabalhos se restringem ao sudeste e sul do Brasil (LunardonBranco et al. 1991, Rodrigues 2003, Rondineli et al. 2007). A ausência de estudos que abordem a composição detalhada e utilização dos recursos alimentares por M. americanus no litoral de Santa Catarina vem de encontro à necessidade de se obter informações biológicas básicas que subsidiem propostas de manejo mais abrangentes para a espécie, tendo em vista seu valor comercial para a pesca artesanal. Em função disso, este trabalho foi realizado com o objetivo de fornecer informações sobre a variação ontogênica e sazonal na alimentação da espécie, contribuindo assim para um melhor entendimento sobre a interação da fauna de peixes com o ambiente costeiro. Material e Métodos Foram realizadas amostragens mensais entre outubro de 2003 e setembro de 2004 na baía de Ubatuba-Enseada (26º11’ S e 48º29’O), litoral norte do estado de Santa Catarina, Brasil (Figura 1). Os exemplares foram coletados mensalmente por meio de nove arrastos consecutivos, com duração de cinco minutos cada, realizados por embarcação artesanal denominada de “arrasteiro”. A embarcação possui oito metros de comprimento, e é equipada com redes de arrasto com portas, contendo sete metros de comprimento, três metros de altura e com malha de três centímetros entre nós consecutivos na região do ensacador. Após a coleta, os indivíduos foram fixados em formol 10% e, posteriormente, conservados em álcool 70%. Em laboratório, os mesmos foram medidos (comprimento padrão), pesados e dissecados para a retirada do estômago. No laboratório de Ictiologia do Museu de História Natural Capão da Imbuia, os conteúdos estomacais foram analisados sob microscópio estereoscópico e realizada a identificação dos itens alimentares com auxílio de bibliografia específica e consulta a especialistas (Melo 1996, Amaral et al. 2005). Para auxiliar nas análises e discussões, os itens macroscópicos identificados na dieta natural da espécie foram posteriormente agrupados em categorias taxonômicas mais amplas (Decapoda, Dendrobranchiata, Caridea, Anomura, Brachyura, Stomatopoda, Amphipoda, Isopoda, Polychaeta, Sipuncula, Osteichthyes e restos de Crustacea). Brasil Figura 1. Localização da área de estudo na baía de Ubatuba-Enseada, São Francisco do Sul, SC, Brasil. Os asteriscos representam os locais dos arrastos. Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 Variação sazonal e mudanças ontogênicas na dieta de Menthichirrus americanus em Santa Catarina, Brasil Para as análises da dieta foram utilizados dois métodos: o método da Freqüência de Ocorrência (FO), que corresponde à freqüência percentual do número de estômagos em que ocorre determinado item alimentar em relação ao número de estômagos com alimento (Zavala-Camin 1996) e o método Volumétrico, pelo qual o volume é expresso em forma percentual, considerando o volume de dado item alimentar em relação ao volume de todos os itens alimentares presentes nos estômagos, permitindo informações sobre a participação de cada item na alimentação (Hyslop 1980, Zavala-Camin 1996). A integração dos dois métodos escolhidos para a análise da alimentação foi realizada através do Índice Alimentar (IAi) de Kawakami & Vazzoler (1980). Neste estudo, assumiu-se que não ocorrem diferenças significativas entre a alimentação de machos e fêmeas, fato esse já verificado para a espécie (Castillo 1986). Para a análise das variações ontogênicas foram determinadas classes de comprimento pelas diretrizes de Sturges (Vieira 1980), a partir da qual foram estabelecidas sete classes de comprimento com intervalos de 3,9 cm, sendo eles 4,2─8,1(classe 1), 8,2─12,1(classe 2), 12,2─16,1(classe 3), 16,2─20,1(classe 4), 20,2─24,1(classe 5), 24,2─28,1(classe 6), 28,2─32,1(classe 7). Para o estudo das variações sazonais e ontogênicas da dieta da espécie foram efetuadas análises de escalonamento multidimensional não métrico (MDS) com sobreposição de cluster de ligação completa. Para estas análises foram utilizados os Índices Alimentares dos itens registrados, sem qualquer transformação dos dados de freqüência. As estações do ano foram definidas da seguinte forma: primavera, de setembro a novembro; verão, de dezembro a fevereiro; outono, de março a maio e inverno, de junho a agosto. As matrizes de similaridade entre as amostras (sazonais e ontogênicas) foram geradas por meio do coeficiente de Bray-Curtis. As análises foram realizadas através do pacote Primer-E Ltd (Clarke & Warnick 2001). Resultados Dentre os 137 tratos digestórios analisados foram identificados 35 itens na dieta da espécie, os quais foram agrupados em 13 categorias taxonômicas, listadas na Tabela I. Os itens alimentares com maior freqüência de ocorrência nos estômagos foram os restos de Crustacea (48,9%), Polychaeta (46%) e Osteichthyes (29,9%) e os menos freqüentes foram Isopoda 349 (2,9%), Anomura (2,2%) e Sipuncula (0,7%), este último ocorrendo em apenas um estômago. As categorias mais representativas na dieta, por ordem de importância alimentar, foram: Crustacea (que incluiu Decapoda não identificados, Dendrobranchiata, Caridea, Anomura, Brachyura, Stomatopoda, Amphipoda, Isopoda e restos de Crustacea) com 51,8%, Osteichthyes com 27,8% e Polychaeta com 14,1%. Este mesmo índice mostrou a pouca importância dos Isopoda (0,01%) e Sipuncula (0,05%) (Tabela II). Os poliquetas constituíram a categoria alimentar mais importante para indivíduos entre 4,2 e 8,1 cm (41,6%) e entre 8,2 e 12,1 cm (36,7%). Entre 12,2 e 16,1 cm, Dendrobranchiata foi a categoria com maior representatividade nos estômagos (28,7%), seguido por Polychaeta (22,8%) que também ocorreu em alta freqüência nos estômagos (57,1%). Entre 16,2 e 20,1 cm, os restos de Crustacea representaram a categoria mais importante (28,2%) e freqüente (64,7%). Também teve alta freqüência de ocorrência Polychaeta (47,1%) e os peixes (35,3%), porém com menores IAi, 25,5% e 25,3% respectivamente. Na classe 20,2 e 24,1 cm, a importância dos crustáceos na dieta foi dada principalmente por Dendrobranchiata (32,7%), muito embora Polychaeta e Osteichthyes tenham sido categorias freqüentes (52% e 40%, respectivamente). Na classe 28,2 e 32,1 cm, as categorias mais freqüentes foram os restos de Crustacea (75%), Decapoda e peixes (50%), este último com a maior representatividade (62,6%) entre as categorias alimentares analisadas (Tabela III). Nas análises de agrupamento, as maiores similaridades foram encontradas entre as classes de comprimento 1-2, 3-4 e 5-6 em função dos valores dos Índices Alimentares (IAi) observados. A similaridade entre as classes 1, 2, 3 e 4 ocorreu em função da representatividade de restos de Crustacea (com maior representatividade nas classes 3-4) e Polychaeta (com maior importância nas classes 1-2). Nas classes 5 e 6, a similaridade verificada ocorreu principalmente em função dos itens Decapoda e Dendrobranchiata. Entre as classes de tamanho consideradas, a menor similaridade foi observada para a classe 7, o que ocorreu em função da representatividade de Osteichthyes na dieta (Figura 2). O agrupamento das classes 1-2 com 3-4 se deve à participação dos poliquetas (com maior importância nas classes 1-2 e com certa representatividade nas classes 3-4) e crustáceos (com maior representatividade nas classes 3-4 e importantes também nas classes 1-2). Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 350 C. F. HALUCH ET AL. Tabela I. Lista dos itens alimentares identificados e agrupamentos taxonômicos (em negrito), obtidos a partir dos conteúdos estomacais de M. americanus analisados. Filo Arthropoda Subfilo Crustacea Ordem Decapoda (Dec) Subordem Dendrobranchiata (Den) Superfamília Penaeoidea Família Penaeidae - Xiphopenaeus kroyeri Família Ogyrididae - Ogyrides alphaerostris Subordem Pleocyemata Infraordem Caridea (Car) Infraordem Anomura (Ano) Superfamília Talassinoidea Superfamília Hippoidea Família Albuneidae - Albunea sp. Lepidopa sp. Infraordem Brachyura (Bra) Família Xanthidae - Pimlumnus sp. Família Portunidae - Callinectes sp. Ordem Stomatopoda (Sto) Família Squillidae - Squilla neglecta Ordem Amphipoda (Amp) Família Gammaridae Família Caprellidae Restos Amphipoda Ordem Isopoda (Iso) Restos Crustacea (RCr) Filo Annelida – Polychaeta (Pol) Família Eunicidae Família Lumbrimeridae Família Sigalionidae Família Glyceridae Restos Polychaeta Filo Sipuncula (Sip) Filo Chordata – Osteichthyes (Ost) Família Engraulidae Ordem Pleuronectiformes Família Paralichthydae Ordem Anguiliformes Família Ophictidae - Ophichthus gomesii Restos Osteichthyes Material não identificado (NI) Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 351 Variação sazonal e mudanças ontogênicas na dieta de Menthichirrus americanus em Santa Catarina, Brasil Tabela II. Freqüência de Ocorrência (%FO), Percentagem Volumétrica (%V) e Índice Alimentar (IAi) das categorias alimentares presentes na dieta de M. americanus. Categorias %FO %V IAi Restos Crustacea 48,9 8,6 15,6 Decapoda não identificados 23,4 14,1 12,2 Dendrobranchiata 21,2 22,8 17,8 Caridea 8,8 1,5 0,5 Anomura 2,2 3,8 0,3 Brachyura 21,2 5,6 4,4 Stomatopoda 7,3 1,6 0,4 Amphipoda 19,0 0,8 0,6 Isopoda 2,9 0,1 0,01 Polychaeta 46,0 8,3 14,1 Sipuncula 0,7 2,0 0,05 Osteichthyes 29,9 25,1 27,8 NI 29,2 5,7 6,2 Tabela III. Freqüência de ocorrência (%FO) e Índices Alimentares (IAi) das categorias alimentares identificadas entre as classes de comprimento padrão (cm) de M. americanus. Em negrito estão destacadas as categorias com maior Freqüência de Ocorrência e sublinhadas aquelas de maior importância alimentar. n = número de indivíduos. Classes de comprimento padrão (cm) 1 2 3 4 5 6 7 n=24 n=32 n=28 n=17 n=25 n=7 n=4 FO IAi FO IAi FO IAi FO IAi FO IAi FO IAi FO IAi RCr 50 25 31,3 14,8 53,6 20,5 64,7 28,2 48 6,9 57,1 11,9 75 4,3 Dec 8,3 0,8 12,5 1,4 25 6,2 23,5 10,1 40 15,5 42,9 21,8 50 22 Den 0 0 9,4 6,9 35,7 28,7 11,8 5 36 32,7 42,9 40,4 0 0 Car 4,2 0,4 9,4 1,5 14,3 0,8 5,9 0,3 4 0,03 28,6 3,2 0 0 Ano 0 0 0 0 0 0 0 0 12 3,9 0 0 0 0 Bra 16,7 3,8 15,6 1,4 14,3 1,0 23,5 1,6 36 9,0 28,6 10,1 25 0,5 Sto 0 0 15,6 1,7 3,6 0,01 5,9 0,4 8 0,7 0 0 25 0,3 Amp 25 7,9 28,1 3,9 17,9 0,6 11,8 0,2 20 0,2 0 0 0 0 Isso 0 0 9,4 0,3 3,6 0,01 5,9 0,07 0 0 0 0 0 0 Pol 41,7 41,6 50,0 36,7 57,1 22,8 47,1 25,5 52 8,9 14,3 0,08 0 0 Sip 0 0 0 0 0 0 0 0 0 0 14,3 6,4 0 0 Ost 16,7 15,9 28,1 18,5 28,6 17,5 35,3 25,3 40 18,0 28,6 2,1 50 62,6 NI 20,8 4,7 34,4 13 25,0 1,9 23,5 3,4 36 4,0 28,6 4 50 10,4 Classe 1 (de 4,2–8,1 cm); Classe 2 (8,2 – 12,1 cm); Classe 3 (12,2 -16,1 cm); Classe 4 (16,2 – 20,1 cm); Classe 5 (20,2- 24,1 cm); Classe 6 (24,2 – 28,1 cm) e Classe 7 (28,2 - 32,1 cm). Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 352 C. F. HALUCH ET AL. Figura 2. Representação R gráfica bidim mensional dass classes de taamanho, com m base no Índice Alimentarr (IAi) de M. americanus, obtida por meio m da análisee de escalonam mento multid dimensional nãão-métrico (M MDS) com sob breposição dee cluster de liggação compleeta. Os traços representam os diferentess graus de sim milaridade obttidos através da análise dee cluster. Classes de tamanhho: 1 (de 4,2––8,1 cm); Claasse 2 (8,2 – 12,1 1 cm); Claasse 3 (12,2 -16,1 cm); Claasse 4 (16,2 – 2 cm); Classe 6 (24,2 – 28,1 2 cm) e Classe 7 (28,2 - 32,1 cm). 20,1 cm); Claasse 5 (20,2- 24,1 Varriações sazonnais entre as importânciass dos itens alim mentares forram observvadas. O item Crustacea Decapoda representtou 32% da alimentaçãoo na primavera, seguuido pelo item Dendrobrannquiata (22,77%). No verrão o item mais representatiivo foi Osteiichthyes (peiixes), seguiddo do item Restoss de Crustaccea. No outono foi verifiicada uma lata predominânc p cia de Polyychaeta (48% %) e Resttos de Crustáácea (27%), eenquanto que no invernoo Den ndrobranquiatta (31,6%)) foi o item maiss representativo, seguido poor Polychaeeta (19,2%)) (Tab bela IV). Na análise dee agrupamen nto sazonal,, umaa maior simillaridade entree os Índices Alimentaress (IAii) foi observvada entre a primavera e o inverno,, em função do item Denddrobranquiataa (22,7% e 31,6 6%, respectivvamente) (Figg. 3). Tabela IV.. Índice Alim mentar (IAi) sazonal dass categorias alimentares de M. amerricanus. PRII=primavera,, VER=verãoo, OUT=outoono, INV=invverno. (n=núúmero de ind divíduos). VER Categorias Alimentarees PRI R OU UT INV n=30 n=366 n=30 n=41 Restos Crusstacea 10,2 16,33 277,0 10,8 Decapoda não n identificaados 31,7 4,7 0,,6 11,8 Dendrobrannchiata 22,7 4,6 1,,8 31,6 Caridea 1,7 <0,11 - 0,8 Anomura - - - 3,3 Brachyura 7,7 6,5 1,,1 1,1 Stomatopodda - 0,5 0,,2 1,3 Amphipodaa 1,0 0,2 0,,1 0,8 Isopoda <0,1 - - <0,1 Polychaeta 5,4 4,5 488,0 19,2 Sipuncula 0,6 - - - Osteichthyees (peixes) 8,4 54,77 166,1 18,6 NI 10,5 8,1 5,,2 0,5 Pan-Americaan Journal of Aquatic A Sciennces (2009), 4(3): 347-356 Variação sazonal e mudanças ontogênicas na dieta de Menthichirrus americanus em Santa Catarina, Brasil 353 Figura 3. Representação gráfica bidimensional de distribuição das amostras sazonais dos Índices Alimentares (IAi) de M. americanus, obtidas por meio da análise de escalonamento multidimensional não-métrico (MDS) com sobreposição de cluster de ligação completa. Os traços representam os diferentes graus de similaridade obtidos através da análise de cluster. PRI=primavera, VER=verão, OUT=outono e INV=inverno. Discussão Menticirrhus americanus apresentou hábito alimentar predominantemente carnívoro e bentófago, apesar da presença de organismos bentopelágicos (Dendrobranchiata) e pelágicos (Engraulidae). A dieta foi representada principalmente por crustáceos, peixes e poliquetas, organismos pertencentes tanto à epifauna como à infauna. A preferência pelos itens registrados já foi constatada por muitos autores para diversos representantes da família Sciaenidae (Amaral & Migotto 1980, Haimovici et al. 1989, Chaves & Vendel 1998, Vendel & Chaves 1998, Camargo & Isaac 2004), sendo que a espécie M. americanus é conhecida por ter hábitos demersais (Smith & Wenner 1985, Rondineli et al. 2007). A boca inferior, típica para a ingestão de organismos que vivem junto ao substrato (Chao & Musick 1977), e o barbilhão utilizado para detecção química e tátil das presas (Vazzoler 1975, Castillo et al. 2000), são estruturas que facilitam a atividades de forrageamento, quando a espécie pode localizar e predar organismos que costumam permanecer enterrados ou semi-enterrados no substrato (Almeida et al. 1997, Zahorcsak et al. 2000). A importância de Crustacea na alimentação da betara foi registrada em diversas localidades ao longo da costa Sudeste/Sul do Brasil (Franco 1959, Castillo 1986, Lunardon-Branco 1990, LunardonBranco et al. 1991, Chaves & Umbria 2003, Rondineli et al. 2007). De fato a importância de crustáceos na alimentação de peixes bentófagos da costa sul do Brasil já foi reportada por Haimovici et al. (1989) e, segundo Edgar & Shaw (1995), a disponibilidade desses organismos é responsável por regular a produção de peixes no Oeste da Austrália. Além dos crustáceos, peixes e poliquetas também apresentam relativa importância na alimentação da espécie (Castillo 1986, Lunardon-Branco et al. 1991, Chaves & Umbria 2003, Rondineli et al. 2007), assim como de outras congêneres (Bearden 1963, Castillo et al. 2000). Com relação aos poliquetas, muito embora este item já tenha sido considerado como preferencial na dieta de espécimes estudados por Amaral & Migotto (1980) no litoral de Ubatuba (SP), eles apresentaram maior importância apenas para indivíduos de menor porte (<12,1 cm) (quando comparados com os itens crustáceos e peixes). Isto pode ter ocorrido em função da facilidade de digestão destes animais (Bregnballe 1961 apud Almeida et al. 1997). Além disso, deve-se também considerar que as carapaças e pereiópodes dos crustáceos podem permanecer por mais tempo no estômago que outros itens, tendendo assim a uma superestimativa da sua real ingestão (Chaves & Vendel 1996). No presente estudo foi observada uma mudança nas presas preferenciais entre as classes de tamanho menores (4,2 a 8,1 cm) e maiores (28,2 a 32,1 cm). Nas demais classes, notou-se a variação na importância de itens secundários, demonstrando que a espécie é capaz de responder a mudanças na utilização ou disponibilidade das potenciais presas. A mudança na dieta das espécies de peixes carnívoros está de fato relacionada com mudanças Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 354 ontogênicas (Wootton 1990, Zavala-Camin 1996), as quais estariam relacionadas com a ocupação de diferentes ambientes (ou estratos) de acordo com seu desenvolvimento (Nikolski 1963), ou com a dificuldade de captura de algumas presas em função de sua grande mobilidade e de flutuações verticais na massa d’água (Carqueija et al. 1995). Os resultados aqui encontrados corroboram os obtidos por Bearden (1963), que constatou uma maior freqüência de poliquetas e anfípodas em indivíduos menores de 13,4 cm. Os poliquetas ocorreram em altas freqüências no presente estudo em exemplares menores (entre 4,2 e 12,1 cm), constituindo a categoria de maior importância, e de importância secundária até 20,1 cm. A preferência por esses organismos em exemplares menores já havia sido constatada por outros autores (Chaves & Umbria 2003, Almeida et al. 1997, Vendel & Chaves 1998). Tal diferenciação no hábito alimentar de uma espécie durante o desenvolvimento é uma adaptação para melhor aproveitamento do alimento disponível, que visa diminuir a competição intraespecífica por alimento ou suprir necessidades fisiológicas que o peixe possa ter em função de migração, maturação sexual e reprodução (Braga & Braga 1987). Muito embora o ambiente pareça não apresentar variações acentuadas no padrão de ocorrência para a maioria dos itens alimentares, alterações sazonais entre os itens principalmente no que diz respeito à importância alimentar foram observadas. A preferência de peixes, principalmente em indivíduos adultos, pode estar associada ao aumento da atividade alimentar dos adultos nos meses do verão. Este aumento na preferência pelo hábito alimentar ictiófago no verão também foi constatado por Vendel & Chaves (1998) na dieta de Bairdiella ronchus no litoral do Paraná. Já a importância dos poliquetas constatada no outono pode estar relacionada principalmente ao fato de que 90% dos exemplares analisados estão contidos nas quatro primeiras classes (entre 4,2 e 20,1 cm) nas quais os poliquetas apresentaram elevada importância na alimentação. Tal plasticidade na dieta das espécies de acordo com a estação pode estar associada à disponibilidade de alimento e aos movimentos migratórios da fauna (Zavala-Camin 1996). Associações entre as mudanças nos itens da dieta e a disponibilidade de invertebrados foram encontradas por Wakabara et al. (1993) e Chaves & Umbria (2003). A partir dos resultados obtidos verificou-se que a espécie possui hábito alimentar bastante diversificado, com a dieta baseada essencialmente em crustáceos, peixes e poliquetas. Juvenis e adultos (machos > 15 cm e fêmeas > 18 cm de comprimento C. F. HALUCH ET AL. total, sensu Muniz & Chaves 2008) compartilharam os mesmos recursos, porém, de formas diferentes. Esse fato pode estar relacionado tanto à redução da competição intra-específica como a diferentes necessidades energéticas, além da acessibilidade do predador à presa. 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Ecology of teleost fishes. Chapman & Hall, London, 404p. Zahorcsak, P., Silvano, R. A. M. & Sazima, I. 2000. Feeding biology of a guild of benthivorous fishes in a sandy shore on south-eastern Brazilian coast. Revista Brasileira de Biologia, 60 (3): 511-518. Zavala-Camim, L. A. 1996. Introdução aos estudos sobre alimentação natural em peixes. EDUEM, Maringá, 129p. Received June 2009 Accepted July 2009 Published online September 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 347-356 Do fallen fruit-dwelling chironomids in streams respond to riparian degradation? FABIO DE OLIVEIRA ROQUE1; TADEU SIQUEIRA2 & SUZANA CUNHA ESCARPINATI3 1 Faculdade de Ciências Biológicas e Ambientais, Universidade Federal da Grande Dourados – UFGD, Unidade II, Rodovia Dourados Ithaum, Km 12, Caixa Postal. 533, CEP 79804-970, Dourados, MS, Brasil. Email: roque.eco@gmail.com.br 2 Programa de Pós-Graduação em Ecologia e Recursos Naturais, Universidade Federal de São Carlos – UFSCar, Rodovia Washington Luis, Km 235, CEP 13564-905, São Carlos, SP, Brazil. Email: tsiqueira.bio@gmail.com 3 Programa de Pós-Graduação em Entomologia e Conservação da Biodiversidade, Universidade Federal da Grande Dourados – UFGD, Unidade II, Rodovia Dourados Ithaum, Km 12, Caixa Postal. 533, CEP 79804-970, Dourados, MS, Brasil. Email: scescarpinati@yahoo.com Abstract. There is little information on the impacts of deforestation on the aquatic insects associated with fallen-fruits in Neotropical streams. Given the argumentation that fallen-fruit dwelling insects may depend on the availability of fruits in streams and consequently on the riparian forest condition, we hypothesized that fallen-fruit dwelling chironomid Endotribelos would differ in streams whose catchments differed in land use, particularly riparian forest conditions. To test this hypothesis we experimentally placed fruits in streams characterized by a gradient of riparian forest degradation We applied correlation analysis between Endotribelos mean density by fruit, number of colonized fruits, and environmental variables. All results evidenced that fallen-fruit chironomid Endotribelos were affected by riparian degradation. Key words: Chironomidae, Endotribelos, lotic systems, anthropogenic impacts, deforestation Resumo. Chironomidae em frutos caídos em córregos respondem à degradação da mata ripícola? Existem poucas informações sobre repostas de insetos que vivem em frutos caídos em córregos frente ao desmatamento e à degradação da mata ripícola na região Neotropical. Considerando a argumentação que insetos vivendo em frutos caídos podem depender da disponibilidade de frutos em córregos e, consequentemente, da condição da floresta ripícola, nós hipotetizamos que Chironomideos Endotribelos seriam diferentes em córregos em diferentes usos do solo, particularmente na condição de mata ripícola. Para testar essa hipótese, experimentalmente colocamos frutos em córregos caracterizados por gradiente de degradação de mata ripícola. Nós avaliamos relações entre a densidade média de Endotribelos por frutos, número de frutos colonizados e variáveis ambientais. Todos os resultados evidenciaram que Chironomidae, particularmente Endotribelos, em frutos respondem previsivelmente à condição da mata ripícola. Palavras-chave: Chironomidae, Entotribelos, sistema lótico, impacto antropico, desmatamento Introduction The effects of land use on aquatic insects have been documented in different parts of the world, but there is still much debate regarding the predictability of the responses of different taxa under different terrestrial disturbances (Bonada et al. 2006). In general, it has been suggested that aquatic insects respond to point source pollution in a very predictable way, but respond to diffuse pollution in a more complex and variable manner (e.g. Allan 2004, Downes et al. 2005). Tropical forests host intriguing interactions between fruits and fruit-eating animals in both terrestrial and aquatic habitats (Janzen 1974, AraujoLima & Goulding 1997, Wantzen & Junk 2006). In these areas, there is a great amount of fruits Pan-American Journal of Aquatic Sciences (2009), 4(3): 357-362 358 falling into streams. This fruit input may occur continuously over the year, and consists mostly of large, fleshy fruits that are of high nutritional value. Therefore, fallen fruits potentially represent an important resource for stream macroinvertebrates (Larned et al. 2001, Roque et al. 2005). Among aquatic insects inhabiting fallen fruits, the larvae of the chironomid Endotribelos Grodhaus, 1987, are the most common insects inside fallen-fruits in Neotropical streams (Roque et al. 2005, Roque & Trivinho-Strixino 2008). Endotribelos larvae have also been reported living in macrophytes, detritus, wood, leaves, and freshwater sponges (Grodhaus 1987; Roque et al. 2005). Endotribelos larvae are a potentially useful group for assessing diffuse anthropogenic impacts on streams, because of their dependence on resources from the riparian forests. Furthermore, there are advantages in using fallen fruits as a natural ecological unit in sampling designs due to their ephemeral, patchy distribution and discrete character that allow testing hypotheses that explicitly address influence of landscape use, habitat, and resources on distribution of aquatic insects. This is particularly worthwhile because in most studies on aquatic systems, the delineation of sampling units is arbitrary, which result, in many cases, in problems with statistical assumptions and biological meanings. There are several mechanisms through which riparian degradation may affect insects inhabiting fallen fruits in aquatic systems. These include a reduction in the number of fallen fruits in the stream, an increase in sediments, and an increase in primary productivity. In this study we hypothesized that riparian degradation may lower the availability of primary resources for chironomids, either directly (i.e. reduce the number of fallen fruits) or indirectly (i.e. reduce the accessibility of fruits by insects, through sedimentation). To test the stated hypothesis, we experimentally placed fruits in streams and evaluated whether abundance and frequency of Endotribelos is related to riparian forest degradation. Considering that (i) resource may be defined as an organism requirement for its survival, growth and reproduction; (ii) the availability of resources can influences the structure and dynamics of ecological systems; (iii) in general the primary resources limit the community productivity (Nowlin et al. 2008), we expect that fallen fruit-dwelling chironomids would differ in streams whose catchments differed in land use, particularly riparian forest conditions. F. O. ROQUE ET AL. Material and Methods Study area. We conducted the experiment in six streams in São Carlos city, southeastern Brazil (22°01’S, 47°53’W). The region was characterized in the past by extensive areas of Cerrado (savanna) and Atlantic semi-deciduous forest (Soares et al. 2003), both considered hot spots of biodiversity (Myers et al. 2000). Currently, the area is dominated by sugar cane plantations, pastures, small forest fragments, and riparian buffer strips along the streams with different levels of connectivity, size and preservation. Regional climate is Cwa (Köppen classification), with wet summer and dry winter. All study sites were first and second order streams with similar topographic gradients (<5o), but located in pasture areas with varied condition of riparian forest. Stream and riparian forest variables. We measured environmental variables at each site to characterize habitat conditions and degree of human disturbance. Conductivity and pH were measured in 3 different sections of each site using a Horiba U-10 or a Yellow Springs-556 water checker equipped with multiple probes. We used the mean of these measures in the statistical analyses. Predominant substrates were estimated visually as the proportion of the stream bottom covered by boulder and cobble (>256 mm), gravel (2-255 mm), sand (0.125-2 mm), and mud (<0.125 mm). To assess physical and biological conditions of the riparian zone and stream channel morphology at the local scale, we applied 7 metrics and their respective scores from the “Riparian Channel and Environmental Inventory” (RCE) for small streams (Petersen Jr. 1992). The RCE scores were applied to each sampling site, which consisted of 100m of stream. These metrics were: 1) land-use pattern beyond the immediate riparian zone, 2) width of riparian zone from stream edge to field, 3) completeness of riparian zone, 4) vegetation of riparian zone within 10m of channel, 5) retention devices, 6) channel sediments, and 7) stream-bank structure. Thus, our RCE final score for each stream refers to the sum of scores of these 7 metrics and higher RCE scores are associated with more intact riparian areas. Selected fruits. Syagrus romanzoffiana (Chamisso) Glassman, popularly called Jerivá, is a common palm in semi-deciduous forest and riparian forests in South-eastern Brazil and their fruits are considered important resources to terrestrial fruiteating animals. The fruit is an ovoid drupe 15cm in diameter with a soft endocarp and woody endocarp. Individuals of these plants produce fruit all the year round. We collected fruits of S. romanzoffiana from Pan-American Journal of Aquatic Sciences (2009), 4(3): 357-362 359 Do fallen-fruits dwelling chironomids in streams respond to riparian degradation? tree individuals in the campus of the Universidade Federal de São Carlos, São Carlos, following three criteria: similar size, ripeness and level of herbivory. Sampling design. We threaded a nylon line through 21 fruits from which we made three “necklaces” with 7 fruits each. These were randomly placed in pool areas of each stream. The insertion of the nylon line in the fruits likely did not influence the larval colonization process, because decomposition starts from the top of the fruit and most of the larvae occupy these areas (personal observation). The fruits were placed in the streams on 1011 August 2006 and removed after seven days. Each fruit was isolated and transported to the laboratory. This period of exposure (seven days) was defined after a preliminary experiment conducted by the authors (unpublished data). No large rainfall event occurred in our study area during this period. Data analysis. We sorted and identified all insects of each fruit. Some fruits were lost during the experiment, so we standardized the number of fruits used in the analyses by those found not completely embedded by sediments. We did not analyze the number of lost fruits and fruit embeddedness as a surrogate measure of anthropogenic impacts, because in two low impacted streams (Canchim and Aeroporto stream), despite having a wide forest buffer, the stream-banks had been disturbed by foraging pigs which covered many fruits by sediments and some fruits were eaten by terrestrial frugivores. Larval densities were expressed as the mean number of larvae per fruit and the proportion frequency of colonized fruits (number of fruit with larvae/total of number). To choose meaningful noncorrelated environmental predictors we carried out a Principal Component Analysis on all measured stream and riparian forest variables. The BrokenStick method (Jackson 1993) was used as a stopping-rule in the PCA. After that we performed correlation analysis for the (Endotribelos) chironomid mean density (log x+1) and frequency of colonized fruits (response variables) against the selected axes of PCA (predictor variables). We report R2 for each correlation. Because geographical data such as these are generally spatially autocorrelated (Legendre 1993), so that degrees of freedom are inflated and Pvalues for R are underestimated. To correct for spatial autocorrelation, we calculated for each correlation the effective number of degrees of freedom according to Dutilleul’s method (Dutilleul 1993). We report adjusted P-values based on the effective degrees of freedom. The analyses were performed using the package Spatial Analysis Macroecology v. 3.0, SAM (Rangel et al. 2006). Results Endotribelos mean density and frequency of colonized fruits varied considerably among streams and the values were highest at conserved areas (Table I). The first principal component axis accounted for 63% of the variability in stream environmental variables and it was the only one selected by Broken stick model. PC1 evidenced a gradient of riparian degradation. Sites with lower PC1 scores were degraded areas (most correlated with high values of conductivity and smaller values of RCE scores) while those with higher PC1 scores were located in conserved areas (correlated with high values of RCE and DO scores) (Tables I and II). Endotribelos mean density and frequency of colonized fruits seem to increase with increasing PCA scores (good condition of riparian forest), as evidenced by positive values of correlations (r2 = 0.77; Padj = 0.06 and r2 = 0.79; Padj = 0.05, respectively). Table I. Endotribelos mean density, frequency of colonized fruits, and environmental variables across different streams in the State of São Paulo, Brazil. Streams 1 2 3 4 5 6 7 8 Mean density 0.00 1.80 0.18 0.61 0.50 0.07 21.80 2.90 Frequency 0.00 0.80 0.18 0.38 0.40 0.07 1.00 1.00 RCE 28 135 65 115 175 24 160 185 pH 6.60 6.70 6.00 7.20 7.00 6.80 6.60 5.40 Conductivity 94 13 12 12 16 16 14 10 DO 2.50 5.70 6.00 7.20 7.30 6.40 5.20 7.90 Canopy 1 3 2 2 3 1 3 3 Lat (Y) -22.039 -21.882 -21.019 -21.954 -21.926 -22.038 -22.044 -21.951 Long (X) -47.829 -47.906 -47.836 -47.837 -47.911 -47.780 -47.824 -47.838 Pan-American Journal of Aquatic Sciences (2009), 4(3): 357-362 360 F. O. ROQUE ET AL. Table II. Summary of the environmental variables and of the results of Principal Component Analysis across different streams in the State of São Paulo, Brazil, and correlation coefficients between principal component scores and the environmental variables. Streams Principal Components Variables Mean SD PC-1 RCE 92 63.99 0.825 6.45 0.64 -0.473 26.16 33.28 -0.879 5.95 1.87 0.938 pH -1 Conductivity (µS cm ) -1 DO (Mgl ) Variance explained % Discussion The negative effects of degradation of riparian cover caused by deforestation, overgrazing and other land use practices on macroinvertebrate communities have been reported worldwide (e.g. Iwata et al. 2003, Allan 2004, Sweeney et al. 2004, Couceiro et al. 2007). Although researchers report that row crop and other forms of intensive cultivation strongly affect stream condition, the influence of pasture agriculture (Strayer et al. 2003) and forest fragmentation (Nessimian et al. 2008) may be less pronounced. Fallen-fruit dwelling insects may depend on the availability of fruits in streams and consequently on the riparian forest condition, and regarding the advantages in using them as indicators of less pronounced and diffuse impacts, it would be expected that the distribution of these animals could be predict based on environmental variables related to anthropogenic impacts. Our results support this expectation. The negative effects of the riparian degradation on frequency of colonized fruits and on Endotribelos mean density by fruit may be attributable to a number of interacting reasons. The principal reasons, by which forest degradation influences stream macroinvertebrate densities, are sedimentation, hydraulic alteration, and loss of large organic matter inputs (Allan 2004). Environmental disturbances in degraded streams, such as sedimentation, have long been suggested to be one of the most important causes for loss of species and reduction in density of some macroinvertebrate groups. The principal mechanisms behind are: (i) increasing turbidity, scouring and abrasion, (ii) impairing substrate suitability for biofilm production, (iii) decreasing food quality causing bottom-up effects through food webs, (iv) in-filling of interstitial habitat that harms crevice-occupying invertebrates (v) coating of gills and respiratory surfaces and (vi) reducing stream habitat heterogeneity (Cordone & Kelly 1961, Quinn et al. 63% (Broken stick 52%) 1992, Wood & Armitage 1997, Wantzen 1998, Allan 2004). An increase in primary productivity is also expected to occur in some deforested small streams, with consequences in macroinvertebrate communities. The most common effect is a positive and food related association between macroinvertebrate abundance and periphyton biomass, and also functional changes characterized by higher dominance of collectors and grazers (Vannote et al. 1980, Bojsen & Jacobsen 2003). In our study, we could observe high amounts of periphyton on the surface of the fruits in the most degraded streams and occurrence of non-specialists fruit dwelling chironomids (e.g. Chironomus) living around the fruits. This observation, associated with the smaller frequency of colonized fruits by Endotribelos, indicates a replacement of “typical dwelling fruit chironomids” by more tolerant taxa. Moreover, animals influenced by or depend on basal food resources from riparian vegetation can suffer additional negative effects on its occurrences and densities due to direct losses, changes and decreases of the basal resources (Benstead & Pringle 2004). From a bioassessment perspective, despite the potential application of fallen-fruit dwelling insect information, we consider that before using Endotribelos as an indicator group of forest degradation, at least for non extreme situations that are more difficult to assess, we need to know threshold levels of disruption involving linkages between terrestrial and stream habitats and resources that affect fallen-fruit dwelling insect abundances. Acknowledgements We thank Dr Karl M. Wantzen (University of Konstanz, Limnological Institute), Dr Luis M. Bini (Universidade Federal de Goiás, Instituto de Ciências Biológicas, Departamento de Biologia Geral) and Ingrid Ng (University of Guelph) for suggestions that improved earlier versions of this Pan-American Journal of Aquatic Sciences (2009), 4(3): 357-362 Do fallen-fruuits dwelling chironomids c inn streams resppond to ripariaan degradationn? manuscript.. 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" " -*(( '1, ,+'% '(+'% '%)'% *Y '-L ,(&$%/+'% " '(($ (+.)'( )' $02,1+' ), <$3-'2,2$6'0,+'(* *0 "&*6'%$, 0?),( H AC *(+.)$%*( "&*6'%$$),* & H%$7*-($),)* )* :' ,.6' :' ,.6' -,($6 2 ,%+'( W C (2*1+'( ), 3$'6'/$, -*2-').+$7, )* , < * *(+.)$%*( "&*6'%$$),* %' 6$+'-,6 (.6 )' $' K-,%)* )' '-+* -,($6 & = H%$7*-($),)* N*)*-,6 )' $' K-,%)* )' '-+* ,+,6 -,($6 A 2 $67, " " ), D ",(+$6&'( W " )* D '2*> K K ! ,-,+, " *(+$%/ 3$'6'/? ,%) 1'%(*-7,+$'% '< +&* '6$7* -$)6*? (*, +.-+6* = 5 , < $% -,>$6 S +' S @ = ( $ 2 8 C T A H" *1*$7*) W.6? 11*2+*) *2+*03*.36$(&*) '%6$%* 1+'3*- Composição e abundância de ovos e larvas de peixes na baía da Babitonga, Santa Catarina, Brasil MICHELI D. P. COSTA1 & JOSÉ MARIA SOUZA-CONCEIÇÃO2 1,2 Universidade da Região de Joinville (Univille) – Unidade São Francisco do Sul, Rodovia Duque de Caxias Km 8, Iperoba – São Francisco do Sul, CEP: 89240.000. Email: 1 midudu_bio@yahoo.com.br; 2 zzze.maria@yahoo.com.br Abstract. Composition and abundance of fish eggs and larvae in the Babitonga Bay, Santa Catarina, Brazil. Estuaries are high biological productivity areas and play an important role as nursery grounds for early life stages of fishes. The aim of this work was to describe the spatial and temporal distribution of ichthyoplankton composition and abundance in the main channel of the Babitonga bay. The mean surface temperature and salinity were 24.3°C and 28.2, respectively. Throughout the study period 4079 fish eggs and 1779 larvae were collected. Higher egg and larval densities were observed in spring, summer, and in the innermost channel area where salinity was lowest. Eighty-one percent of the eggs were Engraulidae. Twenty-five taxa of fish larvae were represented, 7 of which were identified to species. Most abundant families were Sciaenidae, Engraulidae, Gobiidae, Haemulidae, Mugilidae, Sparidae, Blenniidae and Carangidae. Sciaenidae larvae from taxa with economic importance were represented by Bairdiella ronchus, Cynoscion sp., Umbrina sp., Stellifer sp., Menticirrhus sp., Pogonias cromis and Micropogonias furnieri. Spatial and temporal distribution of Lycengraulis grossidens larvae were wide, and it was registered in all sampling sites and seasons, except winter. This study shows the role of Babitonga Bay as a nursery for species of estuarine and coastal fish assemblage. In that area the knowledge on ichthyoplankton is sparse and further studies are recommended. Key words: plankton, ichthyoplankton, subtropical bay, coastal environment, South Atlantic Resumo. Os estuários são áreas altamente produtivas e exercem papel fundamental como berçário para os estágios iniciais de peixes. O objetivo desse trabalho foi descrever a distribuição espacial e temporal da composição e abundância do ictioplâncton no canal principal da baía da Babitonga. A média de temperatura foi 24,3ºC e de salinidade foi 28,2. Durante o período de estudo foram coletados 4079 ovos e 1779 larvas. Na primavera, no verão e na área mais interna onde a salinidade foi menor ocorreram as maiores densidades tanto de ovos quanto de larvas. 81% dos ovos eram de Engraulidae. As larvas foram identificadas como 25 taxa, dos quais 7 até espécie. As famílias mais abundantes foram Sciaenidae, Engraulidae, Gobiidae, Haemulidae, Mugilidae, Sparidae, Blenniidae e Carangidae. Larvas de Sciaenidae de taxa com importância econômica foram representadas por Bairdiella ronchus, Cynoscion sp., Umbrina sp., Stellifer sp., Menticirrhus sp., Pogonias cromis e Micropogonias furnieri. Espacialmente e temporalmente larvas de Lycengraulis grossidens ocorreram amplamente, foram encontradas em todos os pontos amostrais durante o estudo e ausentes apenas no inverno. Este estudo demonstrou o papel da baía da Babitonga como criadouro para espécies da assembléia de peixes estuarina e costeira. O conhecimento sobre o ictioplâncton na área de estudo é escasso e mais estudos são recomendados. Palavras-chave: plâncton, ictioplâncton, baía subtropical, ambiente costeiro, Atlântico Sul Introdução Os estuários são economicamente importantes devido a sua alta produtividade biológica ser associada à ocorrência de estágios iniciais de muitos organismos, ou seja, apresentarem importância como áreas de desova e berçário para muitas espécies (Able 1978, Muelbert & Weiss 1991, Mann & Lazier 1996, Keller et al. 1999, Thayer et al. 1999, Fujita et al. 2002, Pérez-Ruzafa et al. 2004). Os estuários da costa do Atlântico Sul Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 Composição e abundância de ovos e larvas de peixes na baía da Babitonga, Santa Catarina, Brasil são áreas importantes para desova e desenvolvimento de muitos peixes, e essa função merece especial atenção dos cientistas (Sinque & Yamanaka 1982). A dinâmica ictioplanctônica em estuários brasileiros ainda encontra-se sob a ameaça da carência de informações. Embora já existam resultados de trabalhos realizados nas regiões norte e nordeste (Castro & Bonecker 1996, Mafalda Jr. & Silva 1996, Barletta-Bergan et al. 2002, Mafalda Jr. et al. 2004, Bonecker et al. 2007, Bonecker et al. 2009), na região sudeste (Soares et al. 1991, Andreata et al. 1998, Joyeux et al. 2004, Castro et al. 2005, Coser et al. 2007) e na região sul (Muelbert & Weiss 1991, Souza-Conceição et al. 2005, SouzaConceição 2008, Macedo-Soares et al. 2009), ainda é possível verificar ecossistemas com informações escassas a este respeito. Neste contexto, sem ter sido devidamente estudada em relação ao ictioplâncton e sob a ameaça de alterações pela pressão antrópica de entorno, destaca-se a baía da Babitonga, um dos principais complexos estuarinos do Sul do Brasil. Localizada no litoral Norte de Santa Catarina, possui volume aproximado de 7,8 x 108 m3 de água, amplitude de maré de 1,30 m com duração aproximada de seis horas (IBAMA 1998, Knie 2002). A oeste, a baía limita-se na porção setentrional com a Serra do Mar e a leste com a ilha de São Francisco do Sul (IBAMA 1998, Knie 2002, Cremer 2006). Assim a baía pode ser dividida em três grandes segmentos: a região do Canal do Linguado, que contorna a ilha na sua porção sul; a região do Rio Palmital, ao norte e com características estuarinas em boa parte de sua extensão; e o corpo central da baía propriamente dito (Cremer 2006). Um aspecto importante a ser destacado é o grande número de comunidades pesqueiras presentes na baía da Babitonga, as quais conforme dados do Instituto Brasileiro do Meio Ambiente e Recursos Naturais Renováveis (IBAMA 1998) compreendem mais de mil pescadores e respectivas famílias. Esta área estuarina está ligada a base da renovação do sustento destes pescadores, no papel de criadouro de muitas espécies de peixes exploradas na área. Entretanto, este papel ou função da área em questão ainda precisa de informações de base como a distribuição espaço-temporal do ictioplâncton. A informação sobre a composição de espécies e a abundância do ictioplâncton auxilia na localização e descrição de áreas e padrões de distribuição de desovas para espécies não-residentes e locais, servindo também para determinar áreas importantes com a função de berçários (Chute & Turner 2001). Do ponto de vista econômico, o 373 ictioplâncton é o componente mais importante da comunidade zooplanctônica pela relevância na renovação de estoques pesqueiros. Seu estudo é importante para avaliar o potencial comercial de recursos pesqueiros existentes em áreas pouco conhecidas, determinar a susceptibilidade dos mesmos e estabelecer medidas para o aproveitamento sustentável (Navarro-Rodríguez et al. 2006). A baía da Babitonga possui elevado potencial de renovação das populações de peixes para sua área interna e plataforma adjacente. Esta área estuarina possui três quartos de todo o ecossistema manguezal presente em Santa Catarina (Cunha et al. 1999), o que potencializa a função de criadouro de peixes. Desta maneira, o principal objetivo do presente trabalho foi estudar a distribuição espacial e temporal da composição e abundância do ictioplâncton ao longo do canal principal do complexo estuarino da baía da Babitonga durante o transcorrer de um ciclo anual. Material e Métodos A baía da Babitonga está situada no norte do litoral catarinense entre as coordenadas geográficas de 26º02’ - 26º28’S e 48º28’ - 48º50’W, a qual apresenta uma superfície de 130 km² e profundidade média de 6 metros (IBAMA 1998). Neste importante ambiente estuarino foi realizada a aquisição dos dados biológicos e ambientais em quatro pontos amostrais (Fig. 1), sendo um ponto próximo à barra, um na área adjacente ao porto do município de São Francisco do Sul, um intermediário (Ilha do Araújo) e um ponto mais interno (Ilha da Rita). Foram realizadas coletas nos meses de abril, julho, setembro e novembro de 2004, e janeiro e abril de 2005. As amostras foram obtidas com uma rede de plâncton cônica de 40 cm de diâmetro, 200 μm de abertura de malha e equipada com fluxômetro para medir o volume de água filtrado. A rede utilizada no trabalho foi escolhida para abranger os estágios de desenvolvimento de menores classes de tamanho dentro do ictioplâncton conforme Matsuura & Nakatani (1980), Johnson & Morse (1994) e Chute & Turner (2001), reduzindo assim o escape e a extrusão. As coletas ocorreram durante o dia e para reduzir problemas de evasão foi utilizada cor de malha clara. Os arrastos foram oblíquos, integrando toda a coluna d’água e duraram 2 minutos devido à colmatação da rede, sendo repetidos caso isto ocorresse. Foram registradas, por ponto amostral em superfície, a temperatura (°C) através de termômetro de mercúrio (precisão de 0,1°C) e a salinidade através de refratômetro de campo (precisão de 1,0). As amostras foram fixadas em solução Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 374 formalina a 4%. M. D. P. COSTA & J. M. SOUZA-CONCEIÇÃO diferentes (p<0,05) foi utilizado o teste SIMPROF. Os dados de densidade foram transformados através da função Log (x+1), utilizado como coeficiente de distância a similaridade de Bray-Curtis e método de agrupamento pela média de seus valores de similaridade (UPGMA) (Clark & Warwick 1994). Resultados Figura 1. Área de estudo e localização dos pontos amostrais (1: barra; 2: porto; 3: ilha do Araújo; e 4: ilha da Rita) no canal principal da baía da Babitonga. No laboratório foi determinado o biovolume zooplanctônico através do método volumétrico, em mililitros, e posteriormente calculado por cem metros cúbicos (mL.100m-3). Em seguida, o ictioplâncton foi triado sob microscópio estereoscópico binocular, sendo posteriormente calculadas as densidades de ovos e larvas de peixe por cem metros cúbicos (n°.100 m-3). Para a análise qualitativa, os ovos foram identificados em dois grupos, os pertencentes à Engraulidae e outros, e as larvas de peixes foram identificadas ao menor táxon possível de acordo com referências bibliográficas especializadas (Colton & Marak 1969, Russel 1976, Johnson 1978, Matsuura & Nakatami 1979, Fahay 1983, Leis & Rennis 1983, Leis & Trnski 1989, Órtiz-Galindo et al., 1990, Moser 1996, Matsuura & Suzuki 1997, Ré 1999, López et al. 2002, Cuartas et al. 2003, Mata et al. 2004, Richards 2006). A variação dos parâmetros de temperatura e salinidade entre coletas e pontos amostrais foi testada pelo teste não-paramétrico de KruskallWallis (p<0,05). Em caso de significância foi aplicado teste de Dunn (p<0,05). Os testes citados foram realizados através do programa Statistica 6.0. Para o estudo de padrões de distribuição do ictioplâncton uma análise de agrupamento foi realizada através do programa PRIMER 6.1.7 (Plymouth Marine Laboratory, Inglaterra). Para separar os agrupamentos significativamente No transcorrer do estudo a temperatura da água variou de 18 a 28°C, com média de 24,3ºC (Fig. 2) e não apresentou variação significativa (p<0,05) entre os pontos amostrais, porém houve variação significativa (p<0,05) entre as coletas (Tabela I). A salinidade variou de 23 a 36, com média de 28,2 (Fig. 2) e não apresentou variação significativa tanto entre as coletas quanto entre os pontos amostrais. Para a densidade do biovolume zooplanctônico, obteve-se os maiores valores no mês de julho, nos pontos do porto e da barra, quando foi observada grande quantidade de gelatinosos nas amostras. Menores valores ocorreram nas coletas de abril de 2004 e abril de 2005 (Fig. 3), quando foram registrados valores para as características físicas e químicas correspondentes ao fim do verão na área de estudo. No total foram coletados 4079 ovos e 1779 larvas ao longo do período de estudo. Os ovos foram identificados como 3319 de Engraulidae e 760 de outras famílias. Entre as larvas foram identificados 25 taxa ao todo, 8 ao nível de família, 10 de gênero e 7 de espécie (Tabela II). O pico da abundância de ovos ocorreu para todos os pontos amostrais no mês de novembro, sendo que a maior densidade registrada ocorreu na Ilha da Rita. Em relação às larvas, a abundância também foi maior no mês de novembro em todos os pontos amostrais, porém o maior valor de densidade de larvas foi encontrado na Ilha do Araújo (Fig. 3). Ao longo do período de estudo a maior densidade de ovos registrada refere-se a Engraulidae, porém com ocorrência concentrada em setembro, novembro e janeiro. Em novembro foi registrada sua maior abundância para todos os pontos amostrais. Os ovos de outras famílias ocorreram durante todo o estudo, com as maiores densidades em setembro e novembro na Ilha da Rita e em janeiro na Ilha do Araújo (Fig. 3). As famílias Engraulidae, Sciaenidae, Gobiidae, Haemulidae, Mugilidae, Sparidae, Blenniidae e Carangidae foram as mais abundantes (Tabela II). Nos meses de setembro e novembro de 2004 e janeiro de 2005 foi encontrado o maior número de taxa, enquanto que em julho de 2004 foram identificadas somente larvas de Sciaenidae e Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 375 Composição e abundância de ovos e larvas de peixes na baía da Babitonga, Santa Catarina, Brasil variedade de sub-estágios de desenvolvimento entre os ovos e as larvas. 40 40 30 30 Salinidade Temperatura (ºC) Blenniidae. Nas identificações, embora não quantificada, foi observada a presença de grande 20 20 10 10 0 0 A J S N J A A J S N J A Figura 2. Variação média e desvio padrão da temperatura (ºC) e da salinidade nos meses de coleta na baía da Babitonga, Santa Catarina (A: abril, J: julho, S: setembro, N: novembro e J: janeiro). Tabela I. Resultado dos testes não-paramétricos de Kruskall-Wallis (p<0,05) e de Dunn (p<0,05) para as variáveis de salinidade e temperatura (°C) entre os pontos amostrais e entre as coletas (n.s.: não significativo; Ab: abril; Jul: julho; Set: setembro; Nov: novembro; Jan: janeiro). Comparações Parâmetros Pontos Amostrais Coletas Salinidade n.s. n.s. n.s. Ab/04 x Jul/04; Ab/04 x Set/04; Ab/04 x Jan/05; Ab/04 x Ab/05; Jul/04 x Set/04; Jul/04 x Nov/04; Jul/04 x Jan/05; Jul/04 x Ab/05; Set/04 x Nov/04; Set/04 x Jan/05; Set/04 x Ab/05; Nov/04 x Jan/05; Nov/04 x Ab/05 1200 Barra 1000 Porto 800 I.Araújo 600 I.Rita 400 200 1200 Outros (n°.100m-³) Biovolume (mL.100m-³) Temperatura (°C) 800 600 400 200 0 0 A J S N J A 12000 A J A J S N J A 6000 Larvas (n°.100m-³) Eng (n°.100m-³) 1000 10000 8000 6000 4000 2000 5000 4000 3000 2000 1000 0 0 A J S N Meses J A S N Meses J A Figura 3. Variação da densidade do biovolume zooplanctônico (mL.100m-³), ovos de Engraulidae (n°.100m-³), ovos de outras famílias (n°.100m-³) e larvas de peixes (n°.100m-³) para os pontos amostrais no período entre abril de 2004 e abril de 2005 (A: abril, J: julho, S: setembro, N: novembro, J: janeiro). Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 376 M. D. P. COSTA & J. M. SOUZA-CONCEIÇÃO pontos amostrais e meses um gradiente de época mais fria e seca (com baixa abundância de larvas) para época caracterizada por meses mais quentes e úmidos, nos quais foram obtidas as maiores abundâncias de larvas e também o maior número de taxa (Fig. 4). Na análise de agrupamento dois pontos amostrais do mês de julho não foram agrupados aos demais devido a não captura de larvas. Os demais pontos levaram a formação de três grupos (Fig. 4), distinguidos pela sazonalidade da abundância das larvas de peixes. O resultado evidenciou entre 0 Similaridade de Bray-Curtis (%) 20 40 60 Set IA 04 Set P 04 Nov B 04 Set IR 04 Jan B 05 Abr IR 05 Jan IA 05 Jan P 05 Jan IR 05 Nov P 04 Frio e seco Nov IA 04 Nov IR 04 Set B 04 Abr P 04 Abr B 05 Abr P 05 Abr IR 04 Abr IA 05 Abr B 04 Jul IR 04 Jul P 04 Jul B 04 Abr IA 04 100 Jul IA 04 80 Quente e úmido Figura 4. Dendograma de similaridades entre as amostras coletadas na baía da Babitonga nos meses de Abril (Abr), Julho (Jul), Setembro (Set) e Novembro (Nov) de 2004 e Janeiro (Jan) e Abril (Abr) de 2005. As amostras foram agrupadas pela similaridade de Bray-Curtis e método de agrupamento UPGMA sobre a matriz de densidades de larvas transformadas em Log (x+1). Discussão O registro de temperatura exibiu homogeneidade entre os pontos, sem diferenças significativas (p<0,05), porém entre os meses observou-se variação significativa (p<0,05). Os resultados indicaram a importância da variação temporal da temperatura na área de estudo e a ocorrência de dois períodos distintos ao longo do ano. Em estudo pretérito os resultados para estas variáveis físicas e químicas foram semelhantes e o estuário classificado como homogêneo, ou seja, sem a ocorrência de gradientes verticais físico-químicos significativos (IBAMA 1998). A variação com tendência inversa da temperatura com a salinidade está relacionada ao balanço hídrico anual na área da baía da Babitonga, ou seja, principalmente pela sazonalidade das chuvas. A distribuição espaço-temporal do zooplâncton tem forte relação com muitas das propriedades físicas e químicas de um estuário (Lopes 1996, Zucon & Loyola-e-Silva 1993). O biovolume de zooplâncton ocorreu em densidades mais elevadas de julho a janeiro, em paralelo ao aumento observado das densidades de ovos e larvas de peixe. No entanto a maior elevação do biovolume ocorreu em julho, principalmente em decorrência da grande quantidade de gelatinosos observada nas amostras do presente estudo. Segundo Freitas & Muelbert (2004) esta elevação do biovolume em paralelo a do ictioplâncton estaria estrategicamente ligada a maior disponibilidade de alimento para as larvas de peixe geradas. Fatores ambientais como luz, temperatura, salinidade e pressão, e fatores biológicos como concentração de alimento, apresentam importantes gradientes espaçotemporais. Estes gradientes justificam o comportamento de organismos planctônicos que realizam migrações diárias, proporcionando desta forma importantes variações no volume do plâncton no decorrer do tempo (Lopes 2006). A baía da Babitonga está inserida em uma região com evidente sazonalidade, o que proporciona grande variação nas densidades do ictioplâncton ao longo do tempo. Este fato fica evidente ao observar coletas com maiores densidades nos meses de primavera e de início do Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 Composição e abundância de ovos e larvas de peixes na baía da Babitonga, Santa Catarina, Brasil verão em comparação com as demais estações. Macedo-Soares et al. (2009) registraram padrão semelhante na laguna de Ibiraquera e Muelbert & Weiss (1991) para o estuário da Laguna dos Patos, sendo que os autores associaram à variação sazonal da temperatura. A temperatura é uma importante variável ambiental que além de influenciar a distribuição sazonal do ictioplâncton, pode controlar a taxa de crescimento larval (Hakala et al. 2003). A composição de assembléias larvais em águas costeiras pode ser relacionada com o regime das correntes locais, os tipos de habitats e as massas d’água que ocorrem em uma região (Vélez et al. 2005). Os mesmos autores, Weiss & Krug (1977) e Castello & Krug (1978), sugerem para baías estuarinas que as larvas em pré-flexão refletem os padrões espaciais, temporais e as localidades de desova dos adultos, sendo que nas áreas onde as larvas de peixes eram predominantemente espécies residentes, teriam sido retidas pelo padrão de circulação interno destas baías e pelo comportamento larval. O mesmo padrão foi encontrado na baía da Babitonga para espécies residentes como L. grossidens, uma vez que houve maior abundância destas larvas nos dois pontos mais internos (predominantemente em pré-flexão), indicando que são retidas neste ambiente devido à dinâmica do sistema e por sua própria ecologia, além destas áreas serem propícias ao desenvolvimento. Esta constatação permite sugerir em estudos futuros, envolvendo diferentes amostradores, a análise espaço-temporal detalhada de classes de tamanhos e sub-estágios do ictioplâncton na baía da Babitonga. A estrutura da assembléia ictioplanctônica indica resultar da combinação da seleção do local de desova pelos adultos, processos físicos e adaptações biológicas das larvas em relação a estes processos (Powles et al. 1984). Quando se compara as assembléias de larvas de peixes em regiões estuarinas deve ser levada em conta a metodologia empregada, esforço amostral, a extensão dos corpos de água e as condições ambientais (Barletta-Bergan et al. 2002). O método empregado no presente estudo, conforme esperado de acordo com outros autores (Johnson & Morse 1994, Chute & Turner 2001), proporcionou a captura proporcionalmente maior de menores larvas (estágios mais iniciais) e permitiu a análise comparativa de sua distribuição em relação às prováveis áreas de desovas dos adultos conforme Vélez et al. (2005), Weiss & Krug (1977) e Castello & Krug (1978). Este fato, associado a elevadas densidades de ovos nas ilhas do Araújo e da Rita, evidenciou a importância da área mais interna da baía da Babitonga como sítio de desovas de componentes da assembléia de peixes, 377 especialmente daqueles registrados no presente estudo (Tabela II, Fig. 3). Vásquez-Yeomans & Richards (1999) encontraram Engraulidae, Gobiidae e Carangidae entre as dez famílias dominantes para a baía de Ascensión. Castro et al. (2005) registraram em grande abundância Engraulidae, Clupeidae, Sciaenidae, Blenniidae e Gobiidae na baía de Guanabara. Em comparação, excluindo-se Clupeidae que deve ser resultado de uma maior proximidade com o mar no referido estudo, as demais famílias estiveram também entre as mais abundantes na baía da Babitonga (Tabela I). Na baía da Guanabara, as famílias de larvas de peixes pelágicos foram as mais abundantes, com dominância de Engraulidae (Castro et al. 2005). No presente estudo a mais abundante foi Engraulidae, representada por L. grossidens, o qual foi o principal representante pelágico encontrado e o único componente registrado desta família. Os engraulídeos são pequenos, primariamente peixes planctófagos, recrutam em águas costeiras e produzem ovos planctônicos (Moser 1996), sendo que a maioria das espécies possui larvas pelágicas (Richards 2006). As larvas de L. grossidens preferem águas rasas e de menor salinidade, condição encontrada em estuários. Na laguna dos Patos os ovos ocorrem durante todo o ano, principalmente na primavera e verão, desovados em águas costeiras e transportados para a laguna (Weiss & Krug 1977). Esta espécie se desenvolve e cresce neste estuário até a fase de juvenil, quando as larvas se encontram em áreas mais internas da laguna devido a características favoráveis ao término da metamorfose (Weiss & Krug 1977). As larvas desta espécie são mais abundantes em águas de menor salinidade e altas temperaturas, os autores complementam ainda que no caso de larvas com tamanho inferior a vinte milímetros a abundância decresce em direção a altas salinidades e baixas temperaturas (Castello & Krug 1978). A abundância e ampla distribuição espaçotemporal de estágios iniciais de sciaenídeos registrada no presente estudo ressaltam a importância da baía da Babitonga como criadouro de peixes importantes para a pesca. Sciaenidae compreende espécies que habitam ambientes tropicais-temperados marinhos, salobros e de água doce, com integrantes de grande importância comercial (Moser 1996). Muitas espécies desta família usam os estuários como berçários, que devido às suas características aumentam as taxas de sobrevivência, de alimentação e de crescimento, onde sazonalmente dominam o nécton (Sardiña & Carzola 2005). Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 378 Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 Tabela II. Lista taxonômica e densidade em 100m³ dos taxa obtidos para as larvas no canal principal da baía da Babitonga (SC) por mês de coleta em cada ponto amostral (B: barra, P: porto, IA: ilha do Araújo e IR: ilha da Rita). Abril 2004 Taxa Julho 2004 Setembro 2004 B P IA IR B P IA IR Lycengraulis grossidens - 113,0 - 76,2 - - - Gobiesocidae - - - - - - Carangidae - 508,7 - - - Trachurus lathami - - - - 71,2 - - Orthopristis ruber - - Sparidae - Sciaenidae Novembro 2004 P IA IR - 5,5 185,6 194,6 8,8 - - - - - - - - - - 5,5 - - 8,8 - - - - - - - 76,2 - - - - 27,8 25,3 - - - - - - - - - - - - - - - - - - - - 9,2 - - Bairdiella ronchus - - - - - - - - - - - - - Cynoscion sp. - 56,5 - - - - - - - 101,2 171,3 - Umbrina sp. - - - - - - - - - - - Stellifer sp. - 56,5 - - - - - - - - Menticirrhus sp. - - - - - - - - - Pogonias cromis - - - - - - - - Micropogonias furnieri - - - - - - - Kyphosus sp. - - - - - - Mugilidae - - - - - Mugil curema (gaimardianus) - - - - - Blenniidae - - 54,9 - - 18,4 - 8,5 11,1 Gobiidae - 56,5 Sphyraena sp. - - - Citharichthys sp. - - Etropus sp. - Achirus sp. Sphoeroides sp. Haemulidae P IA IR - - - 6,5 - - - - - - - - - - - - IR B 3635,3 144,8 - - - 5,3 - - - 8,1 - 26,8 - - - - - 43,6 - - - 7,7 70,8 85,7 16,3 21,8 59,0 115,5 - - - 9,5 - - 5,3 - - - - - - - - 67,4 93,4 70,8 38,1 16,3 32,7 - - - - - - - - - 1441,0 880,0 22,0 82,1 28,2 13,9 - - 73,4 534,9 305,8 22,0 27,3 75,4 125,7 - - - 13,1 57,1 - 54,5 - - 27,3 - 69,8 - 6,6 - - - - 8,1 54,5 - - 27,3 9,4 - - - - 19,6 15,5 - - - - - - - - - - - - - - - - - - - 10,7 - - - - - - - - - - 7,7 - - - - - - - - - - - - - - - - - - - 8,1 - - - - - - - - - - - - - 16,8 15,5 - - - - - - - - - - - - - - - - - - 7,7 8,8 9,5 - 109,1 375,6 - - - - - - - 6,5 - - - - - - - - - - - 5,5 - - - - - - - - 7,7 - 9,5 32,6 10,9 32,1 27,5 18,2 - - - - - 45,8 121,0 255,5 310,2 111,8 120,7 13,2 - 124,5 33,3 194,0 381,5 168,1 P 400,1 514,4 209,5 179,6 P IA IR B IA B 82,1 47,0 69,8 - - 18,8 13,9 - - 45,6 56,4 27,9 186,6 72,9 54,1 45,8 6,7 19,6 54,9 228,6 - - - - 5,5 278,4 155,7 44,2 19,0 16,3 32,7 37,5 - - - - - - - - 17,7 - - - 32,1 - - - - - - - - - - - - - - 22,2 - - - 9,5 - - - - - - - - - - - - - - - - - - - - - - 9,5 - - - - - - - - - - - - - - - - - - - - - - - 9,5 16,3 10,9 16,0 5,5 - - 27,9 - - - - - - - - - - - - - - - - - - - - - 9,1 9,4 13,9 - - - - M. D. P. COSTA & J. M. SOUZA-CONCEIÇÃO B Abril 2005 Janeiro 2005 Composição e abundância de ovos e larvas de peixes na baía da Babitonga, Santa Catarina, Brasil Foram registradas larvas de Cynoscion sp., Menticirrhus sp., Stellifer sp., M. furnieri, , B. ronchus, Umbrina sp., e P. cromis. Sinque (1980) em seu trabalho com larvas de Sciaenidae na região estuarino-lagunar de Cananéia registrou a presença em menores densidades dos 3 primeiros citados acima e maior para M. furnieri, entretanto para todos os quatro a ocorrência ao longo do ano foi correlata para épocas mais quentes. Gêneros como Cynoscion, Pogonias, Micropogonias e Menticirrhus possuem importância comercial e recreacional (Ditty 1989, Ibama 1998). Na pesca artesanal realizada na área e adjacências da baía da Babitonga um item muito capturado é B. ronchus, a qual foi a mais representativa dentre as larvas registradas. Neste gênero os adultos e juvenis são usualmente encontrados em baías, nos fundos lodosos e arenosos, e a desova ocorre preferencialmente em estuários (Johnson 1978). Além de Sciaenidae, muitos dos organismos identificados são descritos como freqüentes nas capturas da pesca na área de estudo (IBAMA 1998), principalmente os vários exemplos de importância para a categoria artesanal (e.g.: Mugil curema, Citharichthys sp., Sphoeroides sp. e outros) O número de taxa identificados para a baía da Babitonga evidencia sua importância como criadouro de muitos componentes da assembléia de peixes, fato também registrado por vários outros autores em diversos sistemas estuarinos brasileiros (Muelbert & Weiss 1991, Barletta-Bergan et al. 2002, Joyeux et al. 2004, Castro et al. 2005, Bonecker et al. 2007, Coser 2007, Bonecker et al. 2009, Macedo-Soares et al. 2009). No presente estudo foi registrada a ocorrência de ovos e larvas de peixes em todo o canal e em todos os meses amostrados, principalmente na primavera e verão, o que indica que este ambiente estuarino representa uma área de desova e crescimento larval para estes organismos. A alta abundância, variedade e diferentes estágios de peixes observados no ictioplâncton reforçam o importante papel de criadouro da baía da Babitonga, a necessidade de propostas para sua conservação e a sugestão de mais estudos. Agradecimentos Os autores gostariam de agradecer a M. J. Cremer, M. A. Castro-Silva, F. Hardt . À todos os acadêmicos do Laboratório de Planctologia do curso de Biologia Marinha (UNIVILLE) que contribuíram nas coletas. Ao apoio estrutural, logístico e financeiro da Universidade da Região de Joinville (UNIVILLE), do Fundo de apoio à Pesquisa da Univille (FAP/UNIVILLE) e da Fundação de 379 Amparo à pesquisa do Estado de Santa Catarina (FAPESC) para a viabilização deste trabalho. 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A., Watson, W., Arntz, W., Wolff, M. & M. D. P. COSTA & J. M. SOUZA-CONCEIÇÃO Schnack-Schiel, S. B. 2005. Larval fish assemblages in Independencia Bay, Pisco, Peru: temporal and spatial relationships. Marine Biology, 147: 77–91. Weiss, G. & Krug. L. C. 1977. Características do desenvolvimento e metamorfose de Lycengraulis olidus (Engraulidae) e Brevoortia pectinata (Clupeidae) no estuário da lagoa dos Patos, Brasil. Atlântica, 2(1): 83-117. Zucon, M. H. & Loyola-e-Silva, J. 1993. Distribuição espacial de foraminíferos e tecamebas do estuário do rio Piauí, Sergipe. Nerítica, 7(1-2): 57-69. Received April 2009 Accepted July 2009 Published online December 2009 Pan-American Journal of Aquatic Sciences (2009), 4(3): 372-382 Software & Book Review Section Poseidon Linux 3.x - The Scientific GNU/Linux option CHRISTIAN DOS S. FERREIRA1, BERNARDO DOS S. VAZ2, GONZALO VELASCO3, RAFAEL A. TAVARES2, DENIS HELLEBRANDT4 & EDUARDO H. ALBERGONE3 1 IFM-Geomar, Leibniz Institute of Marine Sciences, Kiel, Germany (christian@poseidonlinux.org) Universidade Federal de Pelotas (UFPEL), Pelotas, RS, Brazil 3 Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil. 4 School of Development Studies, University of East Anglia, Norwich, UK 2 Abstract. This software review is about the newest version of Poseidon Linux (3.x). The current Poseidon Linux is a remastering from Ubuntu LTS family (Long Term Support), with extra specific software applicable to many areas of scientific research and education. It contains specialist software for GIS/Mapping, bathymetry, numerical modeling, 2D/3D/4D visualization, bioinformatics, chemistry, statistics, as well as tools for creating simple and complex graphics and programming languages. It also includes basic packages as would be expected on a normal desktop, such as a complete office suite, internet browser, e-mail client, instant messaging, chat, multimedia and many other tools. Poseidon Linux can run in two modes, as a live-DVD or installed on the hard disk. There are versions for 32 and 64 bit computers, and support for Brazilian Portuguese, English, Spanish, French, Greek, Italian and German languages. Resumo. Poseidon Linux 3.x – A opção científica GNU/Linux. Esta resenha trata da nova versão do software Poseidon Linux (3.x). A versão atual é uma remasterização a partir do sistema operacional Ubuntu, família LTS (Suporte de Longo Prazo), com pacotes extras para várias áreas da ciência e educação. Contém programas específicos para SIG/mapeamento, batimetria, modelagem numérica, visualização 2D/3D/4D, bioinformática, química, estatística, bem como ferramentas para elaboração de gráficos simples e complexos e linguagem de programação. Inclui também os programas necessários encontrados num sistema operacional desktop, tais como suporte completo para escritório, navegador de internet, programas para envio e recebimento de mensagens instantâneas, multimídia e várias outras ferramentas. O Poseidon Linux pode ser utilizado de duas formas: diretamente do DVD, sem instalá-lo, ou instalando-o no disco rígido do computador. É apresentado nas versões 32 e 64 bits e pode ser totalmente configurado em Português do Brasil, Inglês, Espanhol, Francês, Grego, Italiano e Alemão. History The Poseidon Linux project started in Brazil, in September 2004 with the goal of building a GNU / Linux distribution for academic and scientific use. It was originally based on Knoppix/Kurumin until 2006, because of the live-CD and Portuguese language support (Ferreira et al. 2006). Three versions were publicly released then (1.2, 1.3 and 2.0). Version 2.0 (from late 2005) was extremely popular within Brazil, receiving excellent reviews from Brazilian press and it was recognized and supported by people like John "Maddog" Hall (Linux International), government institutions like Pan-American Journal of Aquatic Sciences (2009), 4(3): I-VI the Brazilian National Spatial Research Institute (INPE – http://www.inpe.br/), among others. However, requests from scientists and students outside of Brazil pointed out the need for a version with greater language support. By early 2008, a new version was ready. This version (3.0) was a complete redesign, based on Ubuntu 8.04 with Long Term Support – LTS (Canonical Ltd., 2008), which represents a mature Linux distribution, for the first time supporting multiple languages. This helped Poseidon Linux (3.0) to achieve a wider distribution being used in many universities and research institutes around the II world. Along with the release of Poseidon Linux 3.1, a 64 bit version had also debuted, altogether with the "standard" 32 bit version. Advantages of this GNU/Linux distribution As it was created by young scientists for scientific use, this ensures that Poseidon Linux reflects, in most cases, the needs and wishes of this community. It contains several must-have programs for daily use at any college, school or within the laboratory (see Table I). Scientists are able to make suggestions and requests for additional bundled software or additional features by contacting the team at http://www.poseidonlinux.org. This encourages users to take an active interest in their software and should ensure that Poseidon Linux continues to improve and provide for the needs of this community. Poseidon Linux is composed of free, and open source software (with some rare exceptions), that mean that the users are assured of the four principles of GNU General Public License or just GNU-GPL (GNU Project, 2007): freedom to run the program, for whatever purpose; freedom to study how the program works, and adapt it to their needs; freedom to redistribute copies; freedom to improve the program, and release their improvements to the public. This assures the right to employ Poseidon Linux for any kind of use: academic, professional, and of course, personal home use. Following the trend started by Knoppix (Knopper, 2003), Poseidon Linux comes as a LiveDVD that allows the potential user to evaluate the software by running it directly from the optical drive, without installing it on to the hard-drive of his/her computer. Most of the software included runs well from the DVD, but slower than when installed on a hard-drive. If the user likes Poseidon Linux then it is highly recommended to install it on the hard-drive for maximum performance. One possibility is to install Poseidon Linux in parallel with another operating system, such as Windows or Mac OS X, and choosing which system to use from a boot-manager (included). Being open source software, Poseidon Linux has zero cost. Within the current financial global situation, governments and academic institutions have a higher need to reduce expenditure. One option, then, is the use of open source - free software. The saving to a department in software costs becomes particularly apparent when we Pan-American Journal of Aquatic Sciences (2009), 4(3): I-VI C. S. FERREIRA ET AL. analysis the costs of common scientific software needed today in academic work. By using such a system as Poseidon Linux, an institution may save several thousand Euros in software costs and/or licenses. The following table (Table I) shows partially the current software included, and is also used to illustrate an estimated saving by using Poseidon Linux compared to "proprietary" software (prices may vary, but the idea is still valid). Some real cases of Use, to exemplify the usability GIS example. Seabed relief maps in three dimensions from off the Brazilian coast (and some oceanic islands) were produced by Ferreira et al. (2005) and Madureira and Ferreira (2007), using open source software included in Poseidon Linux (Fig. 1). The analysis and visualization was carried out using bathymetric data collected along several scientific acoustic fisheries surveys conducted between 11° and 34°S in the South Western Atlantic. Additional data was obtained from data sets made available on the Internet and used to increase the resolution showing in greater detail many undersea features. These structures were named following the guidelines of GEBCO’s SubCommittee on Undersea Feature Names (SCUFN). These 3D maps show a real application of open source software in Oceanography/Bathymetry. The main software used was: GMT (for filtering and grid interpolation) and GRASS (for grid manipulation and visualization in 3D). This was proven to be a robust, fast and stable combination, allowing analysis and visualization of really large data-sets. Bioinformatic example. Poseidon Linux and its included software were used extensively by Vaz et al. (2008). Part of the work involved sequencing a specific gene from the catfish Rhamdia quelen (GH - growth hormone) and development of 3D models of the tertiary structure from the resulting protein (Fig. 2). Specific software used: ClustalX: was used to align sequences of Growth Hormone (GH) gene querying obtained from Genbank; PerlPrimer: was used to design degenerated primers; Sequin: DNA Sequence Submission Tool was used for submission of the gene sequence to Genbank; PyMol Molecular Graphics System: was used to analysis 3D molecular models of proteins. Proprietary Software Estimated Price (US$) Area GRASS ArcInfo + modules 3D and Spatial + ENVI + Fledermaus 30,000 GIS SPRING ArcEditor 10,000 GIS QGIS / Terraview Arcview 1,500 GIS GMT Surfer 600 GIS PROJ + GDAL + OGR ArcToolbox (in ArcGIS) MB System Caraibes 25,000 Bathymetry and Multibeam processing OpenDX BYVision 3,500 Visualization in 2D/3D/4D Octave Matlab + modules for finance, signal analysis and statistics 4,400 Numerical Modeling Maxima Mathematica 2,495 Math R + Rcmdr + RKward STATISTICA ADVANCED 12,120 Statistics/Math Gperiodic The Elements and Isotopes 300 Chemistry GPSDrive and GPSMan Microsoft MAPPOINT GPS 2009 343.19 GPS maping Dia MS Visio Professional 7 559.95 Diagram QTIPlot OriginPro 8 1,875 Graphics Lyx or Kile Scientific Word 875 Professional Typesetting GChemPaint Symyx Draw 777 Draw Chemical Molecules Fityk PeakFit 575 Curve Fitting QCAD or SAGCAD AutoCAD LT 900 CAD/Engineering GIS III Pan-American Journal of Aquatic Sciences (2009), 4(3): I-VI Free Software Poseidon Linux 3.x – The Scientific GNU/Linux option Table I. Estimated costs of proprietary software compared to some software included in Poseidon Linux. Proprietary Software Estimated Price (US$) Area Virtualbox Vmware 189 Desktop Virtualization Blender Maya or 3D Studio 3,500 Computer Graphics and Animation Audacity Sound Forge 300 Multimedia PostegreSQL or MySQL Oracle 10g (Enterprise) 40,000 Database PostGIS ArcSDE 1,800 Database for GIS GCC Intel C Compiler 400 Programing G77 Intel FORTRAN Compiler 700 Programing ClustalX, NCBI Tools, TreePuzzle, TreeView, and others Vector NTI Advance + Sequence Analysis Software Ruo 4,800 + 10,000 Bioinformatic Cn3D Hyperchem 1,494 Bioinformatic Softwares for a normal desktop (internet, mail,office, etc) Windows, Antivirus, Office, Corel Draw, Photoshop, DVD, CD Burner, Firewall, PDF, HTML, Publishing, etc... 15,000 Softwares for Workstation MapServer ArcIMS 10,000 Webmapping TOTAL (in US$) 168,859.95 For 1 license of each proprietary software C. S. FERREIRA ET AL. Free Software IV Pan-American Journal of Aquatic Sciences (2009), 4(3): I-VI Table I. Estimated costs of proprietary software compared to some software included in Poseidon Linux (continued). V Poseidon Linux 3.x – The Scientific GNU/Linux option Figure 1. Map from the South Brazilian coast (Ferreira et al. 2005). Figure 2. 3D model from Rhamdia quelen Growth Hormone (two disulfide bonds in detail) performed - from modeling to drawing - under Poseidon Linux. Conclusions and Remarks The philosophy behind Poseidon Linux is the same as mainstream science: free access to new technologies and the freedom to exchange knowledge between scientists and the general public. This allows people from developed to developing countries to have the same access to high quality scientific software. Born out of a local effort (in Brazil), to initiate and encourage the use of high quality free software for academic and scientific purposes, Poseidon Linux has evolved and gone far beyond the original aims of the project. Even when there was only a single Portuguese language website, it scored Pan-American Journal of Aquatic Sciences (2009), 4(3): I-VI VI the millionth access hit in 2006 (after only two years of existence), with hits recorded from all over the world. Today’s version 3.1 has support for 7 languages and websites in three languages (check http://www.poseidonlinux.org/). Poseidon Linux has confirmed users in North and South America, several countries in Europe, and Asia. Many of these users are using Poseidon Linux as their main tools and operating system for scientific computing. With these facts in hand, we can conclude that Poseidon Linux has filled an existing gap to provide scientists an alternative to proprietary software and proprietary operating systems (like MS Windows, Mac OS X and UNIX). But Poseidon Linux is not just for scientists; it offers a stable, mature and secure platform for everyday computing. Being Open Source software it offers the student high quality software of the same standard as the academic department they are studying without undue financial burden. Also, for the home user, it offers all the ordinary software for communication, internet, multimedia experience, production packages, and even some games. For more advanced users, it may be a chance to study and improve the tools, since the source code is readily available, and a chance to take open source tools to new and unexplored areas of science and knowledge. Finally the Poseidon Linux team sees it as a solution to avoid the use of pirate software, and all the potential problems that this causes to the academic world. Poseidon Linux can be downloaded from: http://g3pd.ufpel.edu.br/mirrors/poseidon/ Acknowledgements To Dr. Kevin Brown for helping with the text and valuable comments. To Prof. Gilberto Griep (FURG, Brazil) for his support since the beginning of this project. To our mirrors for hosting Poseidon Linux, in special to Adenauer Yamin (UFPEL, Brazil). And of course, to our users around the world. Pan-American Journal of Aquatic Sciences (2009), 4(3): I-VI C. S. FERREIRA ET AL. References Canonical Ltd. 2008. Ubuntu Home Page. World Wide Web eletronic publication, accessible at http://www.ubuntu.com. Accessed 18/08/2009. Ferreira, C. S., Madureira, L. S., Klippel, S., Weigert, S., Habiaga, R. G. P. & Duvoisin, A. C. 2005. Mapas do Relevo marinho das regiões sudeste, sul e central do Brasil: acústica e altimetria. Série documentos REVIZEE: Score Sul. São Paulo. 40p. ISBN 85-98729-10-8. Also accessible at: http://www.mma.gov.br/estruturas/revizee /_arquivos/revizee_relevo.pdf Ferreira, C. dos S., Velasco, G., Vaz, B. dos S., Albergone, E. H. & Hellebrandt, D. 2006. Poseidon Linux – uma distribuição Linux voltada para público acadêmico e científico. PanamJAS, 1(2): III-VI. ISSN 1809-9009. Available at http://www.panamjas.org/published.php GNU Project. 2007. GNU General Public License. World Wide Web eletronic publication, accessible at http://www.gnu.org/copyleft/gpl.html. (Acessed 18/08/2009). Knopper, K. 2003. Knoppix Linux Live CD. World Wide Web eletronic publication, accessible at http://www.knoppix.org. (Accessed 18/08/2009). Madureira, L. S. & Ferreira, C. S. 2008. Mapa 3D da costa brasileira e ilhas oceânicas. Atlas National Geografic, v.2: 91-92, São Paulo, ISBN 978-85-364-0391-5. Vaz, B. S., Cerqueira, G.M., Moreira, C.G.A., Manzke, V.H.B., Andre, J.S. & Moreira, H.L.M. 2006. Rhamdia quelen growth hormone precursor (gh) gene, complete cds. ® GenBank : NIH genetic sequence database. Wide Web eletronic publication, accessible at http://www.ncbi.nlm.nih.gov/entrez/viewe r.fcgi?db=nuccore&id=118498502. (Accessed 18/08/2009).