Inter-relações entre zooplâncton e fitoplâncton mediante herbivoria na Lagoa do Camargo (zona de desembocadura do Rio Paranapanema na Represa de Jurumirim)
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Data
2011-07-19
Autores
Alves, Rachel Cristina Prehl [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os organismos planctônicos são a base das cadeias alimentares no ecossistema aquático e os herbívoros zooplanctônicos, em particular, são importantes para o fluxo de energia nos ecossistemas aquáticos, sendo um elo entre os produtores primários e níveis tróficos mais elevados. Este estudo se propôs a ampliar o conhecimento da herbivoria do zooplâncton sobre o fitoplâncton em uma lagoa marginal ao rio Paranapanema. Foi realizado um experimento in situ, com instalação de enclosures com paredes de polietileno fechados no fundo que permitiram a realização de quatro tratamentos: 0% da densidade natural de zooplâncton (apenas fitoplâncton), 50 % (metade da densidade natural), 100% (densidade natural) e 150% (densidade acima da natural). A variação da densidade do zooplâncton foi conseguida por meio de filtração da água por rede de abertura de malha de 50μm. Água da lagoa também foi coletada. Todos os tratamentos foram realizados em tréplica. O experimento durou 18 dias. As coletas foram realizadas a cada seis dias (quatro coletas). A temperatura foi obtida em campo e água foi coletada para análise de oxigênio dissolvido, saturação, pH, condutividade elétrica, concentrações de fósforo total, nitrogênio total, material em suspensão total, material em suspensão orgânico, material em suspensão inorgânico, clorofila-a e feofitina-a. Foram coletadas também amostras de zooplâncton e fitoplâncton que foram contadas e identificadas, normalmente, até ao nível de espécie. Rotifera teve sua abundância relativa alterada em todos os tratamentos, com o favorecimento de Keratella cochlearis e Polyarthra vulgaris provavelmente porque o enclosure as protegeu de predadores. Cladocera foi dominado em todos os tratamentos por Bosmina freyi e B. hagmanni, bioindicadores de eutrofização...
The planktonic organisms are the basis of food chains in the aquatic ecosystems, and the grazer zooplankton, specifically, are very important to energy flow in the aquatic ecosystems, being a link between primary producers and higher trophic levels. The aim of this study is enhance the knowledge of zooplankton grazing over phytoplankton in a lateral lake by Paranapanema River, Brazil. The experiment was conducted in situ, with installation of enclosures of polyetilene walls, closed at the bottom, which allowed the manipulation of four treatments: 0% of the natural density of zooplankton (phytoplankton only); 50% (half of natural density); 100% (natural density) and 150% (a higher density than the natural). The zooplankton density range was obtained by water filtration in zooplankton web with 50μm mesh. The water of the lake was collected either. All the treatments were made using three replications each one. The experiment was carried out for 18 days. The samplings were made each six days (four samplings). The water temperature was measured at field, and a water sample was collected for dissolved oxygen, saturation, pH, conductivity, and concentrations of total phosphorus, total nitrogen, total suspended matter, organic suspended matter, inorganic suspended matter, chlorophyll-a and pheophytin-a analyses. Samples of zooplankton and phytoplankton were also taken. They were counted and identified until specie level, mostly. Rotifera had its relative abundance changed in all treatments, showing the increasing of Keratella cochlearis and Polyarthra vulgaris, probably because the enclosures protected them from predators. Cladocera dominated all treatments by Bosmina freyi and B hagmanni, which are bioindicators of water euthophication. The absolute abundance of this group was the one that best responded... (Complete abstract click electronic access below)
The planktonic organisms are the basis of food chains in the aquatic ecosystems, and the grazer zooplankton, specifically, are very important to energy flow in the aquatic ecosystems, being a link between primary producers and higher trophic levels. The aim of this study is enhance the knowledge of zooplankton grazing over phytoplankton in a lateral lake by Paranapanema River, Brazil. The experiment was conducted in situ, with installation of enclosures of polyetilene walls, closed at the bottom, which allowed the manipulation of four treatments: 0% of the natural density of zooplankton (phytoplankton only); 50% (half of natural density); 100% (natural density) and 150% (a higher density than the natural). The zooplankton density range was obtained by water filtration in zooplankton web with 50μm mesh. The water of the lake was collected either. All the treatments were made using three replications each one. The experiment was carried out for 18 days. The samplings were made each six days (four samplings). The water temperature was measured at field, and a water sample was collected for dissolved oxygen, saturation, pH, conductivity, and concentrations of total phosphorus, total nitrogen, total suspended matter, organic suspended matter, inorganic suspended matter, chlorophyll-a and pheophytin-a analyses. Samples of zooplankton and phytoplankton were also taken. They were counted and identified until specie level, mostly. Rotifera had its relative abundance changed in all treatments, showing the increasing of Keratella cochlearis and Polyarthra vulgaris, probably because the enclosures protected them from predators. Cladocera dominated all treatments by Bosmina freyi and B hagmanni, which are bioindicators of water euthophication. The absolute abundance of this group was the one that best responded... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Ecossistema aquático, Zooplâncton, Fitoplâncton, Aquatic ecosystems
Como citar
ALVES, Rachel Cristina Prehl. Inter-relações entre zooplâncton e fitoplâncton mediante herbivoria na Lagoa do Camargo (zona de desembocadura do Rio Paranapanema na Represa de Jurumirim). 2011. 142 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2011.