Bacterioplâncton em reservatórios tropicais de geração de energia: variação no espaço e no tempo da estrutura bacteriana em sete reservatórios de Furnas Centrais Elétricas S.A.

Abstract

Density, diversity, biomass and activity of heterotrophic microorganisms have an unquestioned importance on aquatic food web. These attributes have been evaluated in the following energy generation reservoir of FURNAS Centrais Elétricas S.A.: Serra da Mesa (GO), Manso (MT), Itumbiara (GO), Corumbá (GO), Mascarenhas de Moraes (MG), Furnas (MG) e Luis Carlos Barreto (SP). First, bacterial community structure and bacterial carbon supply were estimated in these seven reservoirs at different seasons. Highest bacterial densities were found before the rainy period in all the reservoirs and were correlated with turbidity in all periods. Although the biggest reservoir (Serra da Mesa) presented the highest bacterial carbon supply, it was not always proportional to the reservoir size. After, the bacterial community composition in these reservoirs was evaluated in biogeography context. Specific distribution characteristics were found inside and between the reservoirs. The bacterial density, biomass and composition were evaluated in comparison to the water dilution factor in the reservoirs of Serra da Mesa, Manso, Itumbiara and Corumbá in rainy and dry periods. The influence of dilution effect was not observed in the same way for all variables and nor for all reservoirs. Finally, bacterial community structure and production were studied throughout a vertical profile in the deepest reservoir (Serra da Mesa). Distinct communities were found in the depths relating with dissolved oxygen concentration and nitrogen compounds. Thus, the studied reservoir presented distinct and variations in the space and in the time of bacterial community structure.