Dinâmica fitoplanctônica relacionada às condições ambientais em reservatório de abastecimento público do semiárido brasileiro.

This study investigated the structure and dynamics of phytoplankton in Bitury Reservoir (Pernambuco, Brazil), over two season periods, relating the variations of density to physicochemical characteristics (pH, water temperature, electrical conductivity, turbidity, total phosphorus and total nitrogen). Samples were taken in August and October/2008 (dry period), February and April of 2009 (rainy period) in two seasons and depths. 92 taxa were identified. Bacillariophyceae showed higher densities, while Chlorophyceae showed greater diversity. During the dry period, Melosira varians was dominant, whereas in the rainy period, Aulacoseira granulata, Geitlerinema amphibium and Cylindrospermopsis raciborskii were more abundant. The Canonical Correspondence Analysis showed high correlation between the biotic and abiotic data, in which the temperature and pH were the significant variables. Turbidity and total nitrogen are responsible for light and nutrients availability and affect the specific composition and population densities. [ABSTRACT FROM AUTHOR]