Zooplankton community composition and abundance of two
Brazilian semiarid reservoirs
LEITÃO1, A. C.; FREIRE2, R. H. F.; ROCHA3, O. & SANTAELLA4, S. T.
1 Dep. de Botânica, Ecologia e Zoologia, Centro de Biociências, Universidade Federal do Rio Grande do Norte, CEP 59.072-970, Natal/RN, Brazil. acarrha@yahoo.com
2 Dep. de Hidráulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo, Caixa Postal 359, CEP 13560-250, São Carlos/SP, Brazil. herlon@sc.usp.br
3 Departamento de Biologia Evolutiva, Universidade Federal de São Carlos, Caixa Postal 676, CEP 13.565-905, São Carlos/SP, Brazil. doro@power.ufscar.br
4 Dep. de Engenharia Hidráulica e Ambiental, Universidade Federal do Ceará, Fortaleza/CE, CEP 60455-760, Brazil. sandra@ufc.br
ABSTRACT: Zooplankton communities from Pacajus and Gavião reservoirs of Ceará state (northeast Brazil) were sampled in dry and rainy periods in order to correlate the composition and abundance of zooplankton species with environmental factors. A total of 32 taxa were identified: 19 of Rotifera, 7 of Cladocera and 6 of Copepoda. In the Pacajus reservoir, 25 species were recorded in the dry period and 24 in the rainy period. In the Gavião reservoir, 10 species were recorded in the dry and 24 in the rainy periods. According to Shannon- Weaver index, the diversity of species was lower during the dry season for both reservoirs, which can be related to the higher trophy status presented by these lakes in that time. There was an evident dominance of Copepoda Cyclopoida over Copepoda Calanoida, mainly caused by high densities of Thermocyclops decipiens, particularly in December/ 1998. Diaphanosoma spinulosum and Ceriodaphnia cornuta were important among Cladocera, while Keratella and Brachionus were the most conspicuous genera in the Rotifera assembly. The most abundant rotifer species were Keratella tropica, K. americana, Brachionus calyciflorus, B. havanaensis, and Polyarthra vulgaris. Opportunistic species such as T. decipiens, D. spinulosum, C. cornuta, B. calyciflorus, and K. tropica, found in the two studied reservoirs, can be associated with hypereutrophic waters and disturbed environments.
Key-words: reservoirs, zooplankton, bioindicators, water quality, eutrophication, seasonal changes, semiarid, Brazil.