Influência de tanques-rede na comunidade fitoplanctônica e na qualidade da água em um reservatório tropical: avaliação em duas dimensões espaciais

• Ano de defesa: 2015
• Autor(a) principal: Gabriela Lage Melo
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Ecologia; Conservação e Manejo da Vida Silvestre; Fitoplancto Ecologia; Manejo Ecologia; Agua Qualidade; Tilapia (Peixe) Criação; Peixes Cutura
• Link de acesso: http://hdl.handle.net/1843/BUBD-A3FEH4

This study aims to evaluate the effects of fish cages on water quality of a large tropical reservoir. We have studied the impacts by obtaining samples along two spatial dimensions (horizontal and vertical) in the vicinity of installed net cages. The study was conducted in the reservoir of the Furnas Hydroelectric Plant, (Minas Gerais, Brazil). The samplings were performed in two different periods (April 2013 and June 2014) and samples were obtained along a horizontal and a vertical gradient around the net cages. The sampling stations were located in both major axes that form this reservoir (Sapucaí River and Grande River). To make a more general evaluation, the sampling performed on June/2014 had also included six bays containing no fish farm. The water quality was analyzed based on physical, chemical and the structure of the phytoplankton community. The two axes were naturally distinct in relation to phytoplankton community, and trophic state. There were no phytoplankton horizontal or vertical gradients surrounding the tanks, which could result from water circulation or the short distances between the sampled points. However, the bays with and without cages differed significantly different. The bays containing cages showed higher concentrations of nutrients and higher phytoplankton biomass. The major axes of the reservoir are naturally different, but chemical and physical aspects became more uniform as a consequence of the net cages installation. This could be expected, since the axes were subject to the same type of impact from fish farming activities, which drive the system to eutrophication. However, despite the similar response of phytoplankton biomass increasing on both axes, the differences in the structure of this community were amplified by the presence of cages. This suggests that not just the niche, but also dispersion of these microorganisms, could be fundamental to explain the responses to net cage instalation.