FITOPLANCTON

ABSTRACT
The Araguari and Falsino rivers are located in eastern Amazon, State of Amapá, the most preserved state of the country. The stretch chosen for the development of this research is characterized by an aquatic ecosystem that is under anthropogenic pressure due to activities such as, mining, hydroelectric power generation and urbanization, which contrast with the surrounding areas designed for biodiversity conservation. The aim of this work was to study the phytoplankton of the rivers Araguari and Falsino in a stretch of 87km in different hydrological periods during the year 2011, and also to identify patterns of distribution of phytoplankton biomass (chlorophyll-a) and richness in the longitudinal and time axis of those rivers. Another purpose was to investigate which factors influence the formation of these patterns, and also test whether the algal biomass increases towards the river – reservoir gradient. For this purpose plankton samples were collected in quarterly samplings (February to November) through plankton net for later identification by optical microscopy. Likewise, water samples were collected and preserved for the detection of physical-chemical parameters as well as for the quantification of chlorophyll-a. Multivariate statistical methods were used to investigate the factors that influence the dynamics of phytoplankton in the study area. During the study it was registered 185 taxa, 49 genus and 136 species. The Chlorophyta showed a higher number of taxa, whereas Rhodophyta contributed with only 1% of the taxa recorded. Regarded the frequency, most of the phytoplankton (69%) was considered to be sporadic. The greatest richness of taxa occurred in lentic stretches (reservoir) and in the dry season (November). The biomass concentration was always less than 10µg / L and was also higher in this period. Statistical analysis indicated that the factors that had greater influence on the phytoplankton were temperature and flow velocity. These results may explain the maximum richness and biomass in the dry season when there are higher temperatures and lower intensity of the flow velocity. However, the greatest richness occurred in the reservoir regardless of the seasonal period. Moreover, for the chlorophyll-a it was not observed a consistent spatial gradient. Of the total number of taxa found, 152 are new records for the state of Amapá.
Keywords: Amapá, chlorophyll-a, floristic survey, hydrodynamics, potamoplankton.

O estudo da composição do fitoplâncton torna-se essencial quando se percebe a importância e
influência deste na dinâmica da vida aquática. Conhecer os seus componentes, sua frequência e a
relação com os processos físico-químicos ocorrentes no meio traduz-se no conhecimento da
biodiversidade e do sistema ecológico que ali se desenvolve. Desta forma, este ensaio busca
demonstrar o estado da arte das pesquisas fitoplanctônica no Brasil, bem como o desenvolvimento
destas na região Amazônica e no Estado do Amapá. Observa-se que os estudos sobre fitoplâncton
no Brasil vêm crescendo com o decorrer do tempo, principalmente, em função da formação de novos
profissionais na área. Entretanto na Amazônia tais estudos ainda apresentam-se de forma
insuficiente. No estado do Amapá, estudos ficológicos (pesquisas sobre fitoplâncton) ainda são
pouco desenvolvidos. A geração de dados e informações acerca de sua biodiversidade é primordial
para sua conservação e preservação, como também para subsidiar o desenvolvimento de pesquisas
aplicadas na área.

During the various hydrological periods in 2011, we studied the phytoplankton along an 87-km stretch of the Araguari
and Falsino rivers, which are located in the eastern Brazilian Amazon, in the state of Amapá, Brazil, the most
ecologically preserved state in the country. In the study area, the aquatic ecosystem is under pressure from human
activities such as, mining, hydroelectric power generation and urbanization, which contrast with the surrounding
areas that are designated for biodiversity conservation. The aim of this study was to characterize the composition,
frequency and richness of algae species and also to identify spatial-temporal patterns of taxa distribution. During the
study period, we identified 185 taxa (136 species in 49 genera). The division Chlorophyta (class: Zygnematophyceae)
presented the greatest number of taxa, whereas the division Rhodophyta accounted for only 1% of the taxa recorded.
Most of the species identified (69%) were classified as sporadic in occurrence. The few taxa that were classified as
common belonged mainly to the group Bacillariophyta. Species richness was greatest richness in the lentic stretches
(in a reservoir) and in November (during the dry season). Of the 185 taxa identified, 174 are new records for the
state of Amapá.

El Lago Cajititlán, enfrenta severos problemas de salud ambiental; por ello se emprendió un estudio de biodiversidad del
ftoplancton, con la fnalidad de detectar indicadores biológicos de contaminación y determinar la abundancia relativa de los
géneros en dicho ecosistema. Las algas en el medio ambiente producen benefcios: como el oxígeno y la conversión de energía
luminosa en química, reflejada en la acumulación de biomasa por medio de la fotosíntesis, o bien, daños colaterales como la
producción de toxinas por algas cianóftas. Se establecieron 5 puntos de monitoreo y se recolectaron muestras con frecuencia
mensual durante 2014. La identifcación y clasifcación morfológica se realizó por microscopia óptica. Este documento es el
primero en describir las comunidades predominantes en el lago: cloróftas, seguido por cianóftas y la correlación evolutiva de los
géneros, mediante el empleo de árboles flogenéticos.
El estudio proporcionó expectativas en el área de investigación ya que se identifcaron especies con aplicación en salud ambiental
y salud humana, Scenedesmus spp. y Chlorella spp. Especies que son fuente de biomoléculas de alto valor nutricional como
proteínas y vitaminas, como Monoraphidium spp. De aplicación en la síntesis de biocombustibles, Botryococcus spp. Con aplicación
terapéutica como productoras de antioxidates, inmunomoduladores o productoras de toxinas, como Pseudanabaena spp. Se ha
observado una fuerte relación entre las especies de cianóftas encontradas Microcystis spp.; Anabaena spp. y la muerte de peces
durante el verano.

El fitoplancton es un indicador excelente de la calidad del agua y de la condición del ambiente. Con la finalidad de identificar las especies de microalgas indicadoras de las condiciones hidrográficas de la zona marina y costera de una playa ubicada en la zona central de Venezuela y la variabilidad espacial y temporal de su estructura comunitaria, se realizaron 13 muestreos mensuales durante el período entre abril de 2010 – abril de 2011. Se recolectaron muestras de fitoplancton y se estimaron variables fisicoquímicas de interés para la calidad del agua. La comunidad fitoplanctónica estuvo representada por 168 especies o morfotipos distribuidos en 94 diatomeas, 55 dinoflagelados, ocho clorofitas, cinco euglenofitas y un flagelado, y se evidenciaron cambios temporales en su estructura comunitaria, relacionados con el aporte de aguas continentales durante las épocas de máximas precipitaciones y un ascenso de aguas profundas durante los primeros meses del año. Se evidencia una diversid...

En el presente trabajo se estudiaron las variaciones espaciales y temporales del fitoplancton y su relación con los datos fisicoquímicos, en ríos y arroyos de la Alta Cuenca del Río Bermejo. Se observaron diferencias en las variables fisicoquímicas medidas y la abundancia del fitoplancton espacialmente y a lo largo del ciclo hidrológico. Los promedios de oxígeno disuelto, velocidad de la corriente de agua, nitratos, turbidez y sólidos suspendidos disminuyeron desde febrero a octubre. Bacillariophyceae y Cyanobacteria aumentaron en octubre, en tanto que Chlorophyta, Cryptophyta, Chrysophyceae y Euglenophyta fueron superiores durante la transición lluvia-estiaje. Se registraron relaciones significativas entre las características fisicoquímicas de las aguas y la abundancia de cada uno de los grupos algales.

Phytoplankton constitutes the primary producers of aquatic ecosystems and represents the food chain base that supports the commercial fisheries of most water bodies. Nowadays, there is lack of information on phytoplankton assemblages of most reservoirs in Africa. To contribute with this knowledge, this study was carried out to determine the density and diversity of seasonal variations of phytoplankton species in the Bui dam area of the Black Volta, during the pre-(2011) and post-impoundment (2012) periods. For this, a three-level stratified random sampling approach was adopted for 22 months. Phytoplankton samples were obtained by towing a 0.5m diameter phytoplankton net (35μm mesh size and 0.25m 2 mouth surface area) from a non-motorized canoe through a distance of about 100m against the current from downstream to upstream of the river. In 2011, 35 species of phytoplankton belonging to four classes, Bacillariophyceae (7.6%), Chlorophyceae (43%), Cyanophyceae (48.6%) and Euglenophyceae (0.8%) were identified. In the 2012 sampling, 18 species belonging to three classes, Bacillariophyceae (2.2%), Chlorophyceae (26.1%) and Cyanophyceae (71.7%) were observed. A total of 17 species of phytoplankton, including sp. and Spirulina sp., were absent during the late post-impoundment period. Mean monthly total phytoplankton abundance decreased from June (7 384 cells/m 3) to August (106cells/m 3) in 2011. In 2012 however, mean total phytoplankton decreased from February (1 237cells/m 3) to August (4cells/m 3). The results also showed that variations occurred between seasons among some phytoplankton groups. The dry and pre-wet seasons had significantly (p<0.05) higher mean phytoplankton abundance than the wet season during the 22 months of sampling period. The biotic indices of Shannon-Wiener (H 1) were homogenously distributed in the four hydrological seasons of the two years. The phytoplankton groups, Bacillariophyceae, Chlorophyceae, Euglenophyceae and total phytoplankton differed significantly (p<0.05) between the pre-and post-impoundment periods. The total phytoplankton was also significantly (p<0.05) higher in the upstream station than the downstream station indicating the impact of the impoundment on the downstream ecology. Hence, river management strategies should be implemented by hydro-biologist to lessen the impact of the dam on the downstream ecology. Rev. Biol. Trop. 63 (1): 13-22. Epub 2015 March 01.

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The increased bacterial resistance to antibiotics has caused global concern, prompting the search for new compounds. Because of their abundance and diversity, marine phytoplankton are an important potential source of such compounds. Research on dinoflagellates has led to the discovery of inhibitors of bacterial growth. The marine dinoflagellate Lingulodinium polyedrum blooms in different regions of the world, including Mexico, and is also known to regulate the growth of other species in coastal waters. Here, we investigated the taxonomy of this dinoflagellate and characterized the ability of its extracts to inhibit the growth of two bacteria of medical importance (Vibrio vulnificus and Staphylococcus aureus). Taxonomic characterization was performed by PCR and gene amplification of ITS, and confirmed that the species isolated off the Pacific coast of Mexico was L. polyedrum. To prove the inhibitory effect of L. polyedrum extracts, cultures were harvested by centrifuga-tion. Pellets ...

Este trabajo es parte de un proyecto general que incluye el estudio de la dinámica de las algas en los ecosistemas acuáticos en la provincia de La Pampa (Argentina). El objetivo de esta contribución es citar las especies registradas para Arocena y determinar la calidad saprobiana y de agua del lago. Desde octubre de 2006 hasta agosto de 2007, se tomaron muestras de la temporada en el lago poco profundo de Arocena (departamento de Maracó), La Pampa. Las muestras se recolectaron en seis sitios prefijados con una abertura neta de fitoplancton de malla de 25 micrones. Las variables fisicoquímicas (T ° C, pH, conductividad, nitritos, nitratos, oxígeno disuelto, entre otros) se obtuvieron utilizando sensores portátiles y técnicas de laboratorio posteriores. Estos parámetros proporcionaron una caracterización autecológica de las especies estudiadas y algunas de ellas extendieron el rango de tolerancia de la literatura. De todas las especies incluidas en la lista (251), el 40% eran clorofíc...