Phytoplankton assemblages in lateral lagoons of a large tropical reservoir
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Data
2013-02-01
Autores
Ferrareze, M. [UNESP]
Nogueira, MG. [UNESP]
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Editor
Instituto Internacional de Ecologia
Resumo
O objetivo deste estudo foi analisar a composição e os atributos ecológicos das assembleias fitoplanctônicas de quatro lagoas marginais e canal principal do Reservatório de Rosana (SE, Brasil). Os trabalhos de campo foram realizados em setembro e novembro de 2004, e janeiro, março, maio e agosto de 2005. O número total de táxons identificados foi de 283. Zygnemaphyta foi o grupo com maior número de espécies, seguido por Chlorophyta e Bacillariophyta. Maior riqueza, abundância e biomassa foram observadas nas lagoas, quando comparadas ao canal do rio-reservatório, especialmente durante o período chuvoso. Cryptophyceae e Bacillariophyceae dominaram numericamente as assembleias. Cryptomonas brasiliensis Castro, Bicudo e Bicudo foi a principal espécie do fitoplâncton, em termos de abundância e frequência de ocorrência. Os resultados mostraram que as assembleias fitoplanctônicas são influenciadas principalmente pelos fatores meteorológicos e nutrientes (funções de força). Análises de correlação mostraram que a abundância do fitoplâncton foi limitada por nutrientes (nitrogênio e fósforo). Por sua vez, a abundância fitoplanctônica influenciou positivamente a abundância do zooplâncton, o que indica a predominância de mecanismos de controle ascendente no sistema de lagoas laterais. Os resultados validaram a hipótese, assim como já havia sido demonstrado para peixes e zooplâncton, de que as lagoas laterais têm um proeminente papel na diversidade do fitoplâncton. A incorporação das lagoas laterais em programas ambientais seria uma boa estratégia para a conservação da biota aquática regional, minimizando o impacto negativo do represamento.
This study aimed to analyse the composition and ecological attributes of the phytoplankton assemblages in four lateral lagoons and in the main channel of Rosana Reservoir (Paranapanema River, SE Brazil). Fieldwork was carried out in September and November/2004 and January, March, May and August/2005. A total of 283 taxa was identified. Zygnemaphyta was the most specious group, followed by Chlorophyta and Bacillariophyta. Higher richness, abundance and biomass were observed in the lagoons when compared with the river-reservoir sampling point, especially during the rainy period. Cryptophyceae and Bacillariophyceae dominated numerically. Cryptomonas brasiliensis Castro, Bicudo and Bicudo was the main species of the phytoplankton in terms of abundance and frequency of occurrence. The dynamics of the most important taxa are discussed and the results showed that the phytoplankton assemblages are mainly influenced by meteorological factors and nutrient availability (the main driving forces). Correlation analyses indicated that the assemblage abundance was limited by nutrient (nitrogen and phosphorus). The phytoplankton abundance influenced positively the zooplankton abundance, what indicates the prevalence of bottom-up control routes in the lateral lagoons system. The results validate the hypotheses that lateral lagoons have a prominent ecological role on the phytoplankton diversity, as already previously demonstrated for fish and zooplankton. Therefore, the incorporation of the lateral lagoons in environmental programmes should be a target strategy for the conservation of the regional aquatic biota, minimising the negative impact of the dam.
This study aimed to analyse the composition and ecological attributes of the phytoplankton assemblages in four lateral lagoons and in the main channel of Rosana Reservoir (Paranapanema River, SE Brazil). Fieldwork was carried out in September and November/2004 and January, March, May and August/2005. A total of 283 taxa was identified. Zygnemaphyta was the most specious group, followed by Chlorophyta and Bacillariophyta. Higher richness, abundance and biomass were observed in the lagoons when compared with the river-reservoir sampling point, especially during the rainy period. Cryptophyceae and Bacillariophyceae dominated numerically. Cryptomonas brasiliensis Castro, Bicudo and Bicudo was the main species of the phytoplankton in terms of abundance and frequency of occurrence. The dynamics of the most important taxa are discussed and the results showed that the phytoplankton assemblages are mainly influenced by meteorological factors and nutrient availability (the main driving forces). Correlation analyses indicated that the assemblage abundance was limited by nutrient (nitrogen and phosphorus). The phytoplankton abundance influenced positively the zooplankton abundance, what indicates the prevalence of bottom-up control routes in the lateral lagoons system. The results validate the hypotheses that lateral lagoons have a prominent ecological role on the phytoplankton diversity, as already previously demonstrated for fish and zooplankton. Therefore, the incorporation of the lateral lagoons in environmental programmes should be a target strategy for the conservation of the regional aquatic biota, minimising the negative impact of the dam.
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Palavras-chave
Rio Paranapanema, Reservatório de Rosana, Cryptophyceae, Chlorophyceae, Bacillaryophyceae, Paranapanema River, Rosana Reservoir, Cryptophyceae, Chlorophyceae, Bacillaryophyceae
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 73, n. 1, p. 163-171, 2013.