Meiofauna structure in Tramandaí-Armazém estuary (South of Brazil)
KAPUSTA1, S.C., WÜRDIG1, N.L., BEMVENUTI2, C.E.& OZORIO1, C.P.
1 Universidade Federal do Rio Grande do Sul (UFRGS), Programa de Pós-Graduação em Ecologia, Laboratório de Invertebrados Bentônicos I, Av. Bento Gonçalves, 9500, Bloco 4, Prédio 43.435, Sala 204, Porto Alegre, RS, CEP: 91501-970, Brasil.
2 Fundação Universidade Federal do Rio Grande (FURG), Departamento de Oceanografia, Laboratório de Ecologia de Invertebrados Bentônicos, Caixa postal 474, Rio Grande, CEP: 96203-000, Brasil.
ABSTRACT: The meiofauna spatial and temporal distribution at Tramandaí-Armazém estuary was investigated through 4 seasons (summer, autumn, winter, spring), in 2000, in three environments: Tramandaí lagoon, with constant fresh water inflow; Armazém lagoon, where saline wedge is more frequent; the channel between the lagoons and the Atlantic Ocean. Nematoda was the dominant taxonomic group in the samples, but there was a differentiation in the second most abundant group, being Copepoda co-dominat in Armazém lagoon, Ostracoda and Copepoda in Tramandaí lagoon, and juveniles of Gastropoda (Heleobia australis) in the channel. The meiofauna structure in Armazém, characterized by higher densities (mean 916 ind/10cm2), was different from the other environments, in all seasons. The meiofauna collected samples from Tramandaí (mean 259 ind/10cm2) and channel (mean 373 ind/10cm2) were similar in almost every station, except in spring. Density peaks were evidenced in the summer. The results suggest that the environmental variables considered important in a meso-scale, such as salinity, hydrodynamic, stability of the sediment and temperature are the main conditioners of variability found in the sampled environments.
Key-words: meiofauna, Nematoda, estuary, spatial-temporal distribution.