Spatial and temporal distribution of Nematoda in a subtropical estuary
KAPUSTA1, S.C., WURDIG1, N.L., BEMVENUTI2, C.E. & PINTO2, T.K.
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, Brazil. sikarieck@yahoo.com.br
2 Fundação Universidade Federal do Rio Grande (FURG), Dept. de Oceanografia, Laboratório de Ecologia de Invertebrados Bentônicos, Rio Grande, 96203000, Brazil.
ABSTRACT: The spatial and temporal distribution of Nematoda communities was analysed in three environments: in the Tramandaí lagoon, where there is a constant input of fresh water, in the Armazém lagoon, where saline water enters more often, and in the Channel which links the lagoons to the Atlantic Ocean. A total of 27 genera of Nematoda were recorded. In the Armazém lagoon the Terschellingia, Pseudochromadora, Anoplostoma, Theristus and Metalinhomoeus were more representative. Daptonema and Viscosia were dominant in the Channel and Anonchus, Theristus and Oncholaimellus in the Tramandaí lagoon. Multivariate analysis showed that nematode community structure differs among environments. The density, diversity and number of genera were significantly higher in the Armazém lagoon. A simplified community structure of the Nematoda in the Channel and in the Tramandaí lagoon probably reflects the largest instability found in both environments. This distinction was also visualized in relation to the feeding groups, in the Armazém lagoon there was a dominance of epigrowth feeder and microvores, while the deposit feeders and facultative predators prevailed in the Channel and Tramandaí lagoon. A temporal variation was detected in the Nematoda genera and feeding groups. The highest densities of organisms occurred in the summer. In the Tramandaí-Armazém estuary, the interaction between the salinity, hydrodynamic, availablity of food and temperature conditions influence Nematoda community structure.
Key-words: nematoda, estuary, feeding group, spacial and temporal distribution.