Seasonal effects on zooplanktonic community in a temporary lagoon of northeast Brazil
CRISPIM1, M.C. & FREITAS1, G. T. DE P.
1 Universidade Federal da Paraíba, Centro de Ciências Exatas e da Natureza, Departamento de Sistemática e Ecologia. Cidade Universitária 58039-970. João Pessoa-PB, Brazil.
ccrispim@dse.ufpb.br; gleciatrinta@ig.com.br
ABSTRACT: We describe the influence of the seasonal effects on the zooplankton community in a temporary lagoon (Panati lagoon) of Northeast Brazil. Samples of zooplankton were collected monthly for two years in the littoral zone, by filtering 40 liters of water through a plankton net with 45 mm mesh size. During this study, we characterized rainy and dry seasons in the region. The non-parametric Sperman test was used to determine any correlations between rainfall rate and densities of the most frequent zooplankton species. Rotifers were the dominant members of the zooplankton. The rotifer and cladoceran communities basically did not change qualitatively from one year to the next. Among the constant rotifer species the majority was composed by those common of aquatic vegetation (Lecane, Colurella and Lepadella genera), probably due the large quantity of macrophytes in Panati lagoon. Some zooplankton organisms showed quantitative changes related to dry and rainy seasons. Zooplankton species such as the rotifers Polyarthra dolichoptera, Brachionus patulus, Hexarthra mira, the cladoceran Diaphanosoma spinulosum, and cyclopoid copepods demonstrated a significant negative correlation with rainfall rate. Calanoid copepodites showed a significant positive correlation to rainfall rate in Panati lagoon. The rotifer Conochilus natans and calanoid copepods were also favoured in the rainy season.
Key-words: zooplankton, semi-arid, temporary lagoons.