Estrutura sazonal e espacial do microfitoplâncton no estuário tropical do rio Formoso, PE, Brasil

Abstract

Recebido em 5/11/2007. Aceito em 15/07/2008 RESUMO -(Estrutura sazonal e espacial do microfitoplâncton no estuário tropical do rio Formoso, PE, Brasil). Este trabalho teve como objetivo determinar as variações espaço-temporal do microfitoplâncton e variáveis ambientais no estuário do rio Formoso, litoral sul do estado de Pernambuco. As coletas ocorreram em três pontos, no período chuvoso (maio a julho/2002) e estiagem (outubro a dezembro/2002). As amostras do plâncton foram obtidas através de arrastos horizontais superficiais, com rede de abertura de malha de 64¼m. Foram registrados in situ dados sobre temperatura e transparência e, concomitantemente, coletadas amostras de água utilizando a garrafa tipo Kitahara para a análise de salinidade, pH, oxigênio dissolvido, sais nutrientes e biomassa. Foram identificados 204 táxons predominando o grupo das diatomáceas (75%), destacando-se como dominantes Chaetoceros costatus Pavillard, Chaetoceros curvisetus Cleve, Chaetoceros sp., Coscinodiscus centralis Ehrenberg, seguidas dos dinoflagelados (10,79%), cianofíceas (6,37%), clorofíceas (3,92%), euglenofíceas (3,43%) e silicoflagelados (0,49%). As concentrações de oxigênio demonstraram uma alta capacidade de renovação do ambiente devido ao aporte de águas marinhas; maiores concentrações de nutrientes e biomassa algácea ocorreram durante o período chuvoso e nas baixa-mares. A pluviometria e o aporte marinho foram os parâmetros que mais influenciaram na hidrologia e na distribuição da comunidade fitoplanctônica com reflexo na riqueza taxonômica. Palavras-chave: distribuição espacial, ecologia, estuários, fitoplâncton, sazonalidade, taxonomiaABSTRACT -(Seasonal and spatial structure of microphytoplankton in the tropical estuary of Formoso River, Pernambuco State, Brazil). This work aimed to evaluate spatial and temporal variations of the microphytoplankton and environmental variables in the Formoso River estuary, southern coast of Pernambuco state. The samples were collected at three stations, in the rainy season (May to July/2002) and dry season (October to December/2002). The plankton samples were obtained through horizontal superficial hauls, with a 64ìm-mesh net. Temperature and transparency were recorded in situ and, at the same time, water samples were collected using a Kitahara bottle to analyze salinity, pH, dissolved oxygen, nutrients and biomass. A total of 204 taxa were identified with the diatom group (75%) ranking first; dominant species were Chaetoceros costatus Pavillard, Chaetoceros curvisetus Cleve, Chaetoceros sp., Coscinodiscus centralis Ehrenberg, followed by the dinoflagellates (10.79%), cyanophycea (6.37%), chlorophycea (3.92%), euglenophycea (3.43%) and silicoflagellates (0.49%). Oxygen concentrations evidence a high capacity of environment renewal due to sea-water input; higher concentrations of nutrients and microalgae biomass occurred during the rainy season and at low tide. The parameters rainfall and sea-water input influenced hydrology and phytoplankton community distribution to the greatest ...

Influence of river discharge on phytoplankton structure and nutrient concentrations in four tropical semiarid estuaries

“…This is in agreement with findings for other tropical estuaries in northeastern Brazil where the phytoplankton composition in the rainy season is strongly influenced by the input of freshwater species (SILVA et al, 2009;SANTIAGO et al, 2010).…”

“…The pattern observed in PAC, with higher nutrient concentrations (N-NO 3 -, N-NO 2 -and SRP) in the rainy season, was similar to that of the Formoso estuary, a tropical system also in northeastern Brazil (SILVA et al, 2009). The same pattern has also been observed after storms in tropical systems in Australia and has been attributed to increased leaching of materials from watersheds and river channels (EYRE; TWIGG, 1997).…”

Spatial–temporal variation ofAchiruslarvae (Actinopterygii: Achiridae) in mangrove, beach and reef habitats in north-eastern Brazil

“…However, comparing the larval density data in the present study with peak primary production reported in studies by Silva et al (2004Silva et al ( , 2009 carried out in the same estuary, this synchrony is not apparent. Thus, plankton production may not be a limiting factor for these larvae in the area in question, likely due to the fact that it is a quite productive estuary (Silva et al, 2009) and has a high amount of biomass throughout the year.…”

Alpha and beta diversity of phytoplankton in two subtropical eutrophic streams in southern Brazil

“…According to Silva et al (2009), Chlorophyceae encompasses some of the most widely distributed phytoplankton groups, occurring in all types of continental waters, whereas Luzia (2009) reports that they typically occur in rivers, lakes and shallow reservoirs with turbulence. These observations corroborate the results of current study since the greatest richness of Chlorophyceae occurred at the sampling sites P8 and P2, which are shallow and with few rapids.…”