Books (Libros) by Diego Rodriguez
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Todos los mamíferos de los ríos y mares de América del Sur, más todos los mamíferos marinos de la... more Todos los mamíferos de los ríos y mares de América del Sur, más todos los mamíferos marinos de la Antártida 74 Especies 500 fotografías color 110 ilustraciones 80 mapas Con espectaculares fotos de los más destacados fotógrafos marinos del mundo, este libro explica claramente las características de cada especie: peso, talla, área de distribución, nombre vulgar y científico, clave de identificación para avistajes y varamientos, biología, ecología y conservación. Auspiciado por PNUMA Programa Naciones Unidas para el Medio Ambiente UNESCO Census of Marine Life South America CONICET FONCYT Agencia Nacional de Promoción Científica y Tecnológica Universidad Nacional de Mar del Plata Departamento de Ciencias Marinas UNMdP Departamento de Oceanografía FURG Instituto Nacional de Pesquisas da Amazonia
Bookmarks Related papers MentionsView impact
Papers (Artículos científicos) by Diego Rodriguez
The present study provides information about the diet composition of franciscana dolphin, Pontopo... more The present study provides information about the diet composition of franciscana dolphin, Pontoporia blainvillei, from southern Buenos Aires coast, Argentina. From 2003 to 2011 we collected 66 franciscana dolphins that were incidentally entangled in artisanal fishing nets. We analyzed the stomach contents and estimated the prey size in order to evaluate the diet composition and the overlapping with fisheries. We identified 11 prey species in the stomach contents; only two of
them were important in the diet, the striped weakfish, Cynoscion guatucupa, and the squid, Loligo sanpaulensis. Almost all the prey found in the diet of franciscana dolphins are of commercial interest. The overlapping of target species and prey that are subject to overfishing could enhance the vulnerability of franciscana by reducing food availability.
Bookmarks Related papers MentionsView impact
POLIZZI,P.S., M.B. ROMERO, L.N. CHIODI BOUDET, K. DAS, P.E. DENUNCIO, D.H. RODRÍGUEZ, M.S. GERPE. 2014. Metallothioneins pattern during ontogeny of coastal dolphin, Pontoporia blainvillei, from Argentina. Marine Pollution Bulletin, 80 (1-2): 275-281 Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolp... more Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation.
Bookmarks Related papers MentionsView impact
Bio-energetic models used to characterize an animal's energy budget require the accurate estimate... more Bio-energetic models used to characterize an animal's energy budget require the accurate estimate of different variables such as the resting metabolic rate (RMR) and the heat increment of feeding (HIF). In this study, we estimated the in air RMR of wild juvenile South American fur seals (SAFS; Arctocephalus australis) temporarily held in captivity by measuring oxygen consumption while at rest in a postabsorptive condition. HIF, which is an increase in metabolic rate associated with digestion, assimilation and nutrient interconversion, was estimated as the difference in resting metabolic rate between the postabsorptive condition and the first 3.5 h postprandial. As data were hierarchically structured, linear mixed effect models were used to compare RMR measures under both physiological conditions. Results indicated a significant increase (61%) for the postprandial RMR compared to the postabsorptive condition, estimated at 17.93 ± 1.84 and 11.15 ± 1.91 mL O2 min− 1 kg− 1, respectively. These values constitute the first estimation of RMR and HIF in this species, and should be considered in the energy budgets for juvenile SAFS foraging at-sea.
Bookmarks Related papers MentionsView impact
Larvae of the genus Pseudoterranova constitute a risk for human health when ingested through raw ... more Larvae of the genus Pseudoterranova constitute a risk for human health when ingested through raw or undercooked fish. They can provoke pseudoterranovosis in humans, a fish-borne zoonotic disease whose pathogenicity varies with the species involved, making their correct specific identification a necessary step in the knowledge of this zoonosis. Larvae of Pseudoterranova decipiens s.l. have been reported in several fish species from off the Argentine coasts; however, there are no studies dealing with their specific identification in this region. Here, a genetic identification and morphological characterization of larval Pseudoterranova spp. from three fish species sampled from Argentine waters and from Notothenia coriiceps from Antarctic waters was carried out. Larvae were sequenced for their genetic/molecular identification, including the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2), the first (ITS-1) and the second (ITS-2) internal transcribed spacers of the nuclear ribosomal DNA, and compared with all species of the P. decipiens (sensu lato) species complex (sequences available in GenBank). Further, adults of Pseudoterranova spp. from the definitive host, the southern sea lion, Otaria flavescens, from Argentine and Chilean coasts were sequenced at the same genes. The sequences obtained at the ITS-1 and ITS-2 genes from all the larvae examined from fish of Argentine waters, as well as the adult worms, matched 100% the sequences for the species P. cattani. The sequences obtained at mtDNA cox2 gene for Antarctic larvae matched 99% those available in GenBank for the sibling P. decipiens sp. E. Both MP and BI phylogenetic trees strongly supported P. cattani and P. decipiens sp. E as two distinct phylogenetic lineages and depicted the species P. decipiens sp. E as sister taxon to the remaining taxa of the P. decipiens complex. Larval morphometry was similar between specimens of P. cattani from Argentina, but significantly different from those of P. decipiens sp. E, indicating that larval forms can be distinguished based on their morphology. Pseudoterranova cattani is common and abundant in a variety of fish species from Chile, whereas few host species harbour these larvae in Argentina where they show low levels of parasitism. This pattern could arise from a combination of factors, including environmental conditions, density and dietary preferences of definitive hosts and life-cycle pathways of the parasite. Finally, this study revealed that the life-cycle of P. cattani involves mainly demersal and benthic organisms, with a marked preference by large-sized benthophagous fish.
Bookmarks Related papers MentionsView impact
Deep Sea Research II
The stocks of Southern sea lions (Otaria flavescens, SSL) and South American fur seals (SAFS) tha... more The stocks of Southern sea lions (Otaria flavescens, SSL) and South American fur seals (SAFS) that breed on coastal islands of Uruguay constitute the most important focal concentration of pinnipeds in South America, with a significant increase in SAFS and a steady decrease of SSL over the past decades. Because females are a key element of population dynamics and no information exists on the post-breeding pup rearing period, we studied the foraging patterns of SSL females in the La Plata River Estuary (LPRE) during mid and late lactation (late austral autumn and winter), analyzing the foraging performance, geographic coverage and ontogenetic differences in foraging strategies for a period of 1-5 months. At-sea movements of 22 SSL females (6 subadults and 16 adults) from Isla de Lobos (IL, 35°01’28”S - 54°52’59”W, Uruguay) were monitored using satellite transmitters (SPOT4, SPOT5 and STDR-S16, Wildlife Computers) in 2007 and 2010. An algorithm (McConnell et al., 1992) with a maximum transit speed of 3 m sec-1 was applied to the Argos information, resulting in a total of 2,522 filtered locations. A daily mean of 3.5 ± 1.74 filtered locations per animal was received. One hundred and eighty three foraging trips (FT) were recorded with no significant differences (p< 0.05) between subadults and adults in the duration of FT (6.1 ± 3.15 days), distance travelled per FT (237.2 ± 105.25 km), mean distance from IL (57.2 ± 25.90 km), maximum straight line (Spider) distance (100.2 ± 41.40 km) and transit speed (1.1 ± 1.04 m sec -1). SSL showed directional fidelity to foraging sites, indicated by high mean vector (r) values (0.74 ± 0.14) calculated from FT mean bearings. Kernel ranges for 50% and 95% of all FT locations were 5,420 km2 and 36,222 km2, respectively, and the extension of the foraging areas appeared to be influenced by a combination of bathymetry and ecological boundaries within LPRE. Regardless of their reproductive condition, females showed a strong fidelity to IL, and their foraging activity was restricted to relatively shallow areas (10-100 m) on the continental shelf. During autumn and winter, SSL females made significantly longer FTs than during the breeding season, when lactating females decrease FT duration by increasing transit speed but maintain a similar spatial coverage compared with FT later in lactation. Although several aquatic areas of high priority for conservation in LPRE have been identified and proposed, only 15% of the foraging habitat of SSL females is currently included in these areas. This emphasizes the importance of the inclusion of the at-sea foraging distributions of central point foragers in marine protected areas. If conservation efforts focus only on coastal breeding concentrations, key elements of the life cycle are excluded with potential unpredictable effects.
Bookmarks Related papers MentionsView impact
Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified a... more Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified as Vulnerable A3d by the International Union for Conservation of Nature. Cadmium accumulation was assessed in two geographic groups from Argentina; one inhabits the La Plata River estuary, a high anthropogenic impacted environment, and the other is distributed in marine coastal, with negligible pollution. Despite the environment, marine dolphins showed an increase of renal Cd concentrations since trophic independence; while in estuarine dolphins was from 6 years. This is associated with dietary Argentine anchovy which was absent in the diet of estuarine dolphins, being a trophic vector of cadmium in shelf waters of Argentina. Cluster analysis also showed high levels of cd in association with the presence of anchovy in the stomach. The difference in the fine scale distribution of species influences dietary exposure to Cd and, along with other data, indicates two stocks in Argentina.
Bookmarks Related papers MentionsView impact
Aquatic Mammals
Bookmarks Related papers MentionsView impact
Journal of Experimental Marine Biology and Ecology
We measured the metabolic rate of nineteen wild and three captive, trained Southern sea lions (Ot... more We measured the metabolic rate of nineteen wild and three captive, trained Southern sea lions (Otaria flavescens, Shaw 1800) during three behavioral states: resting in air (V . O2 rest air), resting in water (V . O2 rest water) and submerged swimming (V . O2 subswim) using open flow respirometry. We then used these values to estimate total cost of transport (COT) and cost per stroke (CPS) during submerged swimming. Wild animals were placed in a metabolic chamber, and captive animals were trained to breathe under a plexiglass dome mounted at the end of a pool. General linear modeling was used to determine whether the incidence of each type of response variable (V . O2, CPS, COT, swim speed and stroke rate) could be associated with several explanatory variables (sex, age, animal identity, behavioral state, swimming distance and body mass). The overall mean V . O2 rest air was 6.8 ± 1.1 ml O2 min-1 kg-1 (n= 20 animals; 7 subadult males, 10 sub-adults females, 3 adults females), which was 2.1 times greater than the predicted basal metabolic rate (BMR) for terrestrial mammals of similar size, and neither body mass nor sex had a significant influence. The mean V . O2 rest air when only adults were considered (6.3 ± 0.3 ml O2 min-1 kg-1; n= 3 females) was similar to the overall value. The mean ¬ V . O2 rest water (9.0 ± 0.8 ml O2 min-1 kg-1) and the mean V . O2 subswim (21.2 ± 7.4 ml O2 min-1 kg-1) estimated from repeated measurements in two adult females were 2.9 and 6.8 times greater than the predicted BMR, respectively. Both ¬ V . O2 rest water and V . O2 subswim were significantly greater (1.4 and 3.4 times respectively) than the mean V . O2 rest air estimated in this study, when only adults were compared. The mean COT was 0.14 ± 0.1 ml O2 kg-1 m-1 (2.6 ± 1.0 J kg-1 m-1), and the mean CPS was 0.38 ± 0.3 ml O2-1 kg-1 stroke-1; none of these values were significantly different among animals.
Bookmarks Related papers MentionsView impact
"At-sea behavior and effects of hydrographic conditions on the pelagic habitat use of South Ameri... more "At-sea behavior and effects of hydrographic conditions on the pelagic habitat use of South American fur seals (Arctocephalus australis) seasonally inhabiting the surrounding waters of shallow rocky reefs off Punta Mogotes (Mar del Plata, Argentina) were analyzed integrating geographic locations of fur seal groups (FSGs) with coastal hydrographic conditions and behavioral data in a Geographic Information System. Punta Mogotes rocky reefs represent a potentially high quality patch foraging area, crucial to a
central place foraging species during their pelagic dispersion at sea. Fur seal behavior at-sea was strongly influenced by hydrographic conditions such us bathymetry, Beafourt sea state and sea surface current direction. Fur seals General Use Area (GUA) was associated with the 10m isobaths, whereas Critical Use Area (CUA) was almost completely enclosed within the 5misobaths. A concentration-dispersion dynamic trend according to sea state was evident (GUA Beafourt ≤3 = 3.3km2 vs. GUA Beafourt >3 = 1.7km2), with
a “use area displacement” according to sea surface current direction. A general prevalence of long, at sea resting periods (passive floating was the most frequently performed behavior, and usually for long periods) and a differential occurrence of each behavior associated with Beafourt sea states were detected. During calm seas (Beafourt ≤3), fur seals exhibit passive floating, occupying extended areas, and drifting according to sea surface current direction. With increasing sea states (Beafourt sea state >3), fur seals
tended to perform shallow prolonged immersion and directional movements, and concentrated in restricted areas weakly affected by currents. The importance of floating periods at-sea, probably associated with
resting and digestion, was interpreted as an energy conserving strategy that would allow an increase overall foraging efficiency. Results suggested that the ability of fur seals to perform certain behaviors that will allow completing physiological process and ultimately determine reproduction and survival success, would be conditioned by the hydrographic regime at foraging areas. This last could be extrapolated to other fur seal species spending long times at-sea, both as part of migration movements or during typical long foraging round trips."
Bookmarks Related papers MentionsView impact
Natura Neotropicalis, 2011
Patterns of sutural closure and its variability in the skull of the South American fur seal Arcto... more Patterns of sutural closure and its variability in the skull of the South American fur seal Arctocephalus australis were studied based on the analysis of 73 Arctocephalus australis skulls. The order and pattern of 12 skull sutures closure were determined using a closure criteria degree: from 1 to 4 (1: open, 2: less than 50 % closed, 3: more than 50 % closed, 4: closed). The sutures showed differences in their closure patterns, according to the functional regions of the skull. Sutures of the braincase region were the first to show partial and total closure. The rostral region (e.g. sutures of the facial, rostral and palatal bones) was the last to close, although some of the sutures remained open. Based on the studied sutures, the closure advance of the skull has posterior– anterior and dorsal–basal direction. The sexual dimorphism in pinnipeds is widely studied based on craneometrical methods; however, the skull sutures do not show differences between males and females
in the pattern and order of closure during the skull growth. The
studied sutures could be considered of two types: informative and
non–informative of the physical development in the species, being
the basioccipital–basisphenoid and the basisphenoid–presphenoid the
best sutures indicating the physical maturity of the skull.
Bookmarks Related papers MentionsView impact
"Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) ... more "Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) incidentally captured in artisanal fisheries of the northern coast of Argentina. Twenty-eight percent of the dolphins presented PD in their stomach, but no ulcerations or obstructions were recorded in the digestive tracts. PD ingestion was more frequent in estuarine (34.6%) than in marine (19.2%) environments, but the type of debris was similar. Packaging debris (cellophane, bags, and bands) was found in 64.3% of the dolphins, with a lesser proportion (35.7%) ingesting fishery gear fragments (monofilament lines, ropes, and
nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after
trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina."
Bookmarks Related papers MentionsView impact
The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three ... more The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains—the Caribbean, the Pacific, and the Atlantic— ranging in latitude from 12uN to 55uS. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current, the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution. These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends, and will also provide relevant information for science based policies.
Bookmarks Related papers MentionsView impact
"ABSTRACT
1. The common dolphins (genus Delphinus) have one of most problematic taxonomies and c... more "ABSTRACT
1. The common dolphins (genus Delphinus) have one of most problematic taxonomies and complex distribution patterns of all cetaceans. Although the taxonomy and the distribution seem to have been clarified somewhat in the eastern North Pacific and Indo-Pacific Oceans, many questions remain in the Southwestern Atlantic Ocean (SWA). We review the biogeography of Delphinus in the SWA.
2. We reviewed data from strandings, incidental catches and sightings since 1922. Systematic surveys were conducted in five major areas. Twenty-one natural history collections were examined, and 135 skulls were measured.
3. A total of 184 records of common dolphins were compiled. Delphinus apparently occurs in three stocks in the SWA: one located in northern Brazil and two from southeastern Brazil (~22°S) to central Argentina (~42°S). Two distinct patterns in habitat use were observed by depth: in southeastern Brazil, sightings were restricted to coastal waters with water depths ranging from 18m to 70m. On the other hand, in the area that extends from southern Brazil to Central Argentina (from 28°S to 42°S), sightings were recorded in deeper waters, ranging from 71m to 1435m, with the exception of occasional coastal sightings. The cranial analyses demonstrated that both short-beaked common dolphins Delphinus delphis and long-beaked common dolphins Dephinus capensis occur in the SWA.
4. In the SWA, Delphinus seems to occur near areas of high productivity. One stock is associated with the productive waters discharged by the Amazon River and possibily with the coastal upwelling system off the coast of Venezuela, while the other stocks are associated with the Cabo Frio upwelling system and the Subtropical Convergence. Our results indicate that the current taxonomy does not adequately reflect the amount of variation within the genus in the world."
Bookmarks Related papers MentionsView impact
In marine mammals, the transition period between lactation and independent feeding provides
an o... more In marine mammals, the transition period between lactation and independent feeding provides
an opportunity to evaluate the influence of the first solid food on heavy metal concentrations in
their tissues at early stages of their life cycle. The aim of the present study was to compare mercury, cadmium,
zinc and copper levels in lactating and recently weaned South American fur seal Arctocephalus
australis pups from Uruguay and northern Argentina, in order to evaluate the heavy metal intake
through solid food shortly after weaning. Heavy metal concentrations in liver, muscle and kidney were
determined by atomic absorption spectroscopy. Mercury levels in suckling pups reached up to 0.60 and
0.40 μg g–1 wet weight in liver and kidney tissues, respectively. This group presented lower levels of
cadmium, with maximum concentrations of 0.11 μg g–1 and 0.17 μg g–1 in liver and kidney tissues, respectively.
Weaned pups showed significantly higher levels of both cadmium (liver = 6.93 ± 4.73 μg g–1;
kidney = 20.89 ± 5.00 μg g–1) and mercury (liver = 3.91 ± 1.16 μg g–1, kidney = 0.57 ± 0.15 μg g–1). These
significantly higher levels, and a clear distributional pattern between organs, strongly suggest a rapid
intake of heavy metals during the first months after weaning. The presence of mercury and cadmium in
weaned pups also indicates relevant early predation on fish and squid, representing a considerable contribution
of both metals, but mainly cadmium, for South American fur seal pups. This sharp accumulation
could be used as an indicator of the weaning process. Furthermore, heavy metal levels of pups
would constitute a relevant baseline level in the early life of the South American fur seal.
Bookmarks Related papers MentionsView impact
"Copper, zinc, mercury, and cadmium were studied
in the muscle, liver, and kidney of three adult... more "Copper, zinc, mercury, and cadmium were studied
in the muscle, liver, and kidney of three adults and
one juvenile Southern sea lion (Otaria flavescens)
found dead on the beaches of Argentina. Heavy
metal concentrations were determined by Atomic
Absorption Spectrophotometry; cold vapor and
air/acetylene flame techniques were applied for
mercury and for the rest of the metals, respectively.
Previous acid digestion was made with nitric/sulphuric
(Hg) and perchloric/nitric (Cd, Zn, Cu)
mixtures. Quality was checked with a Certified
Reference Material. Mercury concentrations were
highest in the liver, whereas cadmium levels were
highest in the kidney. The juvenile and adults presented
the same tissue distribution pattern for all
studied metals. Hepatic mercury concentrations
ranged from 23.3 mg/g (juvenile female) to 47.6
mg/g (adult male), with renal cadmium concentrations
between 0.8 mg/g and 5.7 mg/g, respectively"
Bookmarks Related papers MentionsView impact
Genetic and morphological studies were carried out on acanthocephalans belonging to Corynosoma Lu... more Genetic and morphological studies were carried out on acanthocephalans belonging to Corynosoma Lu¨ he,
1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which
were recovered from both definitive and intermediate hosts in Argentinian waters. The aims were to estimate
the level of genetic differentiation between the two taxa at any stage of their life-cycle, to provide genetic
(allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans
were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of
Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D’Orbigny (definitive
hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for
C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were
identified, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of
both A. australis and M. leonina as C. australe. A high level of genetic differentiation (DNei=¥: INei=0.00)
between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the
two species from the body-cavity of the fish Cynoscion guatucupa (Cuvier) collected from the same geographical
area were identified genetically. Morphological patterns, such as the number of hooks and hook
rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and
meristic differences, in addition to ecological data, enabled the identification of these two species at cystacanth,
juvenile and adult stages. However, a number of morphological and morphometric features of the
Argentinian material were different to those of C. australe and C. cetaceum described from other regions of
the world.
Introduction
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Uploads
Books (Libros) by Diego Rodriguez
Papers (Artículos científicos) by Diego Rodriguez
them were important in the diet, the striped weakfish, Cynoscion guatucupa, and the squid, Loligo sanpaulensis. Almost all the prey found in the diet of franciscana dolphins are of commercial interest. The overlapping of target species and prey that are subject to overfishing could enhance the vulnerability of franciscana by reducing food availability.
central place foraging species during their pelagic dispersion at sea. Fur seal behavior at-sea was strongly influenced by hydrographic conditions such us bathymetry, Beafourt sea state and sea surface current direction. Fur seals General Use Area (GUA) was associated with the 10m isobaths, whereas Critical Use Area (CUA) was almost completely enclosed within the 5misobaths. A concentration-dispersion dynamic trend according to sea state was evident (GUA Beafourt ≤3 = 3.3km2 vs. GUA Beafourt >3 = 1.7km2), with
a “use area displacement” according to sea surface current direction. A general prevalence of long, at sea resting periods (passive floating was the most frequently performed behavior, and usually for long periods) and a differential occurrence of each behavior associated with Beafourt sea states were detected. During calm seas (Beafourt ≤3), fur seals exhibit passive floating, occupying extended areas, and drifting according to sea surface current direction. With increasing sea states (Beafourt sea state >3), fur seals
tended to perform shallow prolonged immersion and directional movements, and concentrated in restricted areas weakly affected by currents. The importance of floating periods at-sea, probably associated with
resting and digestion, was interpreted as an energy conserving strategy that would allow an increase overall foraging efficiency. Results suggested that the ability of fur seals to perform certain behaviors that will allow completing physiological process and ultimately determine reproduction and survival success, would be conditioned by the hydrographic regime at foraging areas. This last could be extrapolated to other fur seal species spending long times at-sea, both as part of migration movements or during typical long foraging round trips."
in the pattern and order of closure during the skull growth. The
studied sutures could be considered of two types: informative and
non–informative of the physical development in the species, being
the basioccipital–basisphenoid and the basisphenoid–presphenoid the
best sutures indicating the physical maturity of the skull.
nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after
trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina."
1. The common dolphins (genus Delphinus) have one of most problematic taxonomies and complex distribution patterns of all cetaceans. Although the taxonomy and the distribution seem to have been clarified somewhat in the eastern North Pacific and Indo-Pacific Oceans, many questions remain in the Southwestern Atlantic Ocean (SWA). We review the biogeography of Delphinus in the SWA.
2. We reviewed data from strandings, incidental catches and sightings since 1922. Systematic surveys were conducted in five major areas. Twenty-one natural history collections were examined, and 135 skulls were measured.
3. A total of 184 records of common dolphins were compiled. Delphinus apparently occurs in three stocks in the SWA: one located in northern Brazil and two from southeastern Brazil (~22°S) to central Argentina (~42°S). Two distinct patterns in habitat use were observed by depth: in southeastern Brazil, sightings were restricted to coastal waters with water depths ranging from 18m to 70m. On the other hand, in the area that extends from southern Brazil to Central Argentina (from 28°S to 42°S), sightings were recorded in deeper waters, ranging from 71m to 1435m, with the exception of occasional coastal sightings. The cranial analyses demonstrated that both short-beaked common dolphins Delphinus delphis and long-beaked common dolphins Dephinus capensis occur in the SWA.
4. In the SWA, Delphinus seems to occur near areas of high productivity. One stock is associated with the productive waters discharged by the Amazon River and possibily with the coastal upwelling system off the coast of Venezuela, while the other stocks are associated with the Cabo Frio upwelling system and the Subtropical Convergence. Our results indicate that the current taxonomy does not adequately reflect the amount of variation within the genus in the world."
an opportunity to evaluate the influence of the first solid food on heavy metal concentrations in
their tissues at early stages of their life cycle. The aim of the present study was to compare mercury, cadmium,
zinc and copper levels in lactating and recently weaned South American fur seal Arctocephalus
australis pups from Uruguay and northern Argentina, in order to evaluate the heavy metal intake
through solid food shortly after weaning. Heavy metal concentrations in liver, muscle and kidney were
determined by atomic absorption spectroscopy. Mercury levels in suckling pups reached up to 0.60 and
0.40 μg g–1 wet weight in liver and kidney tissues, respectively. This group presented lower levels of
cadmium, with maximum concentrations of 0.11 μg g–1 and 0.17 μg g–1 in liver and kidney tissues, respectively.
Weaned pups showed significantly higher levels of both cadmium (liver = 6.93 ± 4.73 μg g–1;
kidney = 20.89 ± 5.00 μg g–1) and mercury (liver = 3.91 ± 1.16 μg g–1, kidney = 0.57 ± 0.15 μg g–1). These
significantly higher levels, and a clear distributional pattern between organs, strongly suggest a rapid
intake of heavy metals during the first months after weaning. The presence of mercury and cadmium in
weaned pups also indicates relevant early predation on fish and squid, representing a considerable contribution
of both metals, but mainly cadmium, for South American fur seal pups. This sharp accumulation
could be used as an indicator of the weaning process. Furthermore, heavy metal levels of pups
would constitute a relevant baseline level in the early life of the South American fur seal.
in the muscle, liver, and kidney of three adults and
one juvenile Southern sea lion (Otaria flavescens)
found dead on the beaches of Argentina. Heavy
metal concentrations were determined by Atomic
Absorption Spectrophotometry; cold vapor and
air/acetylene flame techniques were applied for
mercury and for the rest of the metals, respectively.
Previous acid digestion was made with nitric/sulphuric
(Hg) and perchloric/nitric (Cd, Zn, Cu)
mixtures. Quality was checked with a Certified
Reference Material. Mercury concentrations were
highest in the liver, whereas cadmium levels were
highest in the kidney. The juvenile and adults presented
the same tissue distribution pattern for all
studied metals. Hepatic mercury concentrations
ranged from 23.3 mg/g (juvenile female) to 47.6
mg/g (adult male), with renal cadmium concentrations
between 0.8 mg/g and 5.7 mg/g, respectively"
1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which
were recovered from both definitive and intermediate hosts in Argentinian waters. The aims were to estimate
the level of genetic differentiation between the two taxa at any stage of their life-cycle, to provide genetic
(allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans
were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of
Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D’Orbigny (definitive
hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for
C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were
identified, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of
both A. australis and M. leonina as C. australe. A high level of genetic differentiation (DNei=¥: INei=0.00)
between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the
two species from the body-cavity of the fish Cynoscion guatucupa (Cuvier) collected from the same geographical
area were identified genetically. Morphological patterns, such as the number of hooks and hook
rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and
meristic differences, in addition to ecological data, enabled the identification of these two species at cystacanth,
juvenile and adult stages. However, a number of morphological and morphometric features of the
Argentinian material were different to those of C. australe and C. cetaceum described from other regions of
the world.
Introduction
them were important in the diet, the striped weakfish, Cynoscion guatucupa, and the squid, Loligo sanpaulensis. Almost all the prey found in the diet of franciscana dolphins are of commercial interest. The overlapping of target species and prey that are subject to overfishing could enhance the vulnerability of franciscana by reducing food availability.
central place foraging species during their pelagic dispersion at sea. Fur seal behavior at-sea was strongly influenced by hydrographic conditions such us bathymetry, Beafourt sea state and sea surface current direction. Fur seals General Use Area (GUA) was associated with the 10m isobaths, whereas Critical Use Area (CUA) was almost completely enclosed within the 5misobaths. A concentration-dispersion dynamic trend according to sea state was evident (GUA Beafourt ≤3 = 3.3km2 vs. GUA Beafourt >3 = 1.7km2), with
a “use area displacement” according to sea surface current direction. A general prevalence of long, at sea resting periods (passive floating was the most frequently performed behavior, and usually for long periods) and a differential occurrence of each behavior associated with Beafourt sea states were detected. During calm seas (Beafourt ≤3), fur seals exhibit passive floating, occupying extended areas, and drifting according to sea surface current direction. With increasing sea states (Beafourt sea state >3), fur seals
tended to perform shallow prolonged immersion and directional movements, and concentrated in restricted areas weakly affected by currents. The importance of floating periods at-sea, probably associated with
resting and digestion, was interpreted as an energy conserving strategy that would allow an increase overall foraging efficiency. Results suggested that the ability of fur seals to perform certain behaviors that will allow completing physiological process and ultimately determine reproduction and survival success, would be conditioned by the hydrographic regime at foraging areas. This last could be extrapolated to other fur seal species spending long times at-sea, both as part of migration movements or during typical long foraging round trips."
in the pattern and order of closure during the skull growth. The
studied sutures could be considered of two types: informative and
non–informative of the physical development in the species, being
the basioccipital–basisphenoid and the basisphenoid–presphenoid the
best sutures indicating the physical maturity of the skull.
nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after
trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina."
1. The common dolphins (genus Delphinus) have one of most problematic taxonomies and complex distribution patterns of all cetaceans. Although the taxonomy and the distribution seem to have been clarified somewhat in the eastern North Pacific and Indo-Pacific Oceans, many questions remain in the Southwestern Atlantic Ocean (SWA). We review the biogeography of Delphinus in the SWA.
2. We reviewed data from strandings, incidental catches and sightings since 1922. Systematic surveys were conducted in five major areas. Twenty-one natural history collections were examined, and 135 skulls were measured.
3. A total of 184 records of common dolphins were compiled. Delphinus apparently occurs in three stocks in the SWA: one located in northern Brazil and two from southeastern Brazil (~22°S) to central Argentina (~42°S). Two distinct patterns in habitat use were observed by depth: in southeastern Brazil, sightings were restricted to coastal waters with water depths ranging from 18m to 70m. On the other hand, in the area that extends from southern Brazil to Central Argentina (from 28°S to 42°S), sightings were recorded in deeper waters, ranging from 71m to 1435m, with the exception of occasional coastal sightings. The cranial analyses demonstrated that both short-beaked common dolphins Delphinus delphis and long-beaked common dolphins Dephinus capensis occur in the SWA.
4. In the SWA, Delphinus seems to occur near areas of high productivity. One stock is associated with the productive waters discharged by the Amazon River and possibily with the coastal upwelling system off the coast of Venezuela, while the other stocks are associated with the Cabo Frio upwelling system and the Subtropical Convergence. Our results indicate that the current taxonomy does not adequately reflect the amount of variation within the genus in the world."
an opportunity to evaluate the influence of the first solid food on heavy metal concentrations in
their tissues at early stages of their life cycle. The aim of the present study was to compare mercury, cadmium,
zinc and copper levels in lactating and recently weaned South American fur seal Arctocephalus
australis pups from Uruguay and northern Argentina, in order to evaluate the heavy metal intake
through solid food shortly after weaning. Heavy metal concentrations in liver, muscle and kidney were
determined by atomic absorption spectroscopy. Mercury levels in suckling pups reached up to 0.60 and
0.40 μg g–1 wet weight in liver and kidney tissues, respectively. This group presented lower levels of
cadmium, with maximum concentrations of 0.11 μg g–1 and 0.17 μg g–1 in liver and kidney tissues, respectively.
Weaned pups showed significantly higher levels of both cadmium (liver = 6.93 ± 4.73 μg g–1;
kidney = 20.89 ± 5.00 μg g–1) and mercury (liver = 3.91 ± 1.16 μg g–1, kidney = 0.57 ± 0.15 μg g–1). These
significantly higher levels, and a clear distributional pattern between organs, strongly suggest a rapid
intake of heavy metals during the first months after weaning. The presence of mercury and cadmium in
weaned pups also indicates relevant early predation on fish and squid, representing a considerable contribution
of both metals, but mainly cadmium, for South American fur seal pups. This sharp accumulation
could be used as an indicator of the weaning process. Furthermore, heavy metal levels of pups
would constitute a relevant baseline level in the early life of the South American fur seal.
in the muscle, liver, and kidney of three adults and
one juvenile Southern sea lion (Otaria flavescens)
found dead on the beaches of Argentina. Heavy
metal concentrations were determined by Atomic
Absorption Spectrophotometry; cold vapor and
air/acetylene flame techniques were applied for
mercury and for the rest of the metals, respectively.
Previous acid digestion was made with nitric/sulphuric
(Hg) and perchloric/nitric (Cd, Zn, Cu)
mixtures. Quality was checked with a Certified
Reference Material. Mercury concentrations were
highest in the liver, whereas cadmium levels were
highest in the kidney. The juvenile and adults presented
the same tissue distribution pattern for all
studied metals. Hepatic mercury concentrations
ranged from 23.3 mg/g (juvenile female) to 47.6
mg/g (adult male), with renal cadmium concentrations
between 0.8 mg/g and 5.7 mg/g, respectively"
1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which
were recovered from both definitive and intermediate hosts in Argentinian waters. The aims were to estimate
the level of genetic differentiation between the two taxa at any stage of their life-cycle, to provide genetic
(allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans
were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of
Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D’Orbigny (definitive
hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for
C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were
identified, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of
both A. australis and M. leonina as C. australe. A high level of genetic differentiation (DNei=¥: INei=0.00)
between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the
two species from the body-cavity of the fish Cynoscion guatucupa (Cuvier) collected from the same geographical
area were identified genetically. Morphological patterns, such as the number of hooks and hook
rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and
meristic differences, in addition to ecological data, enabled the identification of these two species at cystacanth,
juvenile and adult stages. However, a number of morphological and morphometric features of the
Argentinian material were different to those of C. australe and C. cetaceum described from other regions of
the world.
Introduction
working on the subjects of marine biodiversity and oceanography. When the idea of the Census of Marine Life (CoML)
was proposed following the Symposium held during the IAPSO-IABO conference in Mar del Plata in October 2001,
there was a wide response from the marine scientific community. Information about current research projects, as well
as plans for future work in the context of the CoML, were then obtained from about 70 scientists (Appendix I) belonging
to 12 institutions located along the Argentinean coast (Appendix II, Figure 1). This has been used to illustrate what
is currently being pursued in marine biodiversity in Argentina and which subjects are considered as priority for future
research in the area. This paper is, thus, not an historical update of the knowledge of marine biodiversity, but it attempts
to give an idea of the current situation and what is planned for the future. The development of an extensive database of
what is known on marine biodiversity in the region is considered to be a necessity, but it constitutes a complete project
on its own; as such it is included in the proposals for future work (see Future Work in this paper). It is emphasised that
this synthesis is not exhaustive in the content of the topics being studied or in the number of researchers working in
marine biodiversity in the country. It is, though, considered to be a representative sample of the knowledge in marine
science in Argentina today. This is a starting point for the CoML project in South America and it is hoped that, as it
develops, it will be improved by the active participation, advice and experience of many other scientists in the region.