TROPHIC RELATIONS BETWEEN POLYCHAETA AND ACHIRUS DECLIVIS (CHABANAUD, 1940) (TELEOSTEI : SOLEIDAE) IN THE RIVER SERGIPE ESTUARY (NORTHEASTERN, BRAZIL)
Farias, M. C. V. 1,2 & Couto, E. C. G. 2
1PRODEMA, Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, 58000-000, João Pessoa, PB, Brazil
2Departamento de Biologia, Universidade Federal de Sergipe, J. Rosa Elze, 49100-000, São Cristóvão, SE, Brazil
The Class Polychaeta are an important prey resource for several species of benthic and demersal marine fishes. The group are of particular interest because, by identification to the family level, it is possible to glean information about their feeding behaviour and whether they are of a sessile or errant habit. Detritivores (deposit- and suspension-feeders) are generally sessile or occasionally motile whereas carnivores and omnivores tend to have greater locomotion capabilities. The inter-relationships between species of these forms are fundamental to our understanding of local trophic web. With the specific objective of evaluating the contribution of polychaetes to the diet of demersal and benthic fishes from the Sergipe estuary, otter-trawl catches were carried out on the channel of Sergipe River (between 5 and 12 metres depth) in the winter of 1980 and summer of 1981. In this study, the contribution of polychaetes to sole (Achirus declivis) diet was studied. 30 % of stomachs were found to be empty but the remaining 65 % contained polychaetes. From these, 6 families, 7 genera and 5 species were identified. 29 % of the polychaetes found were carnivores, mainly Eunicida; 14 % were omnivores (family Nereididae) and 57% were deposit-feeders, mainly Capitellidae, Opheliidae and Spionidae. Capitella capitata was present in 60 % of the stomachs examined. In the sole´s mid-size classes, polychaetes may represent 100 % of the stomach contents. The deposit-feeders (the most abundant polychaete trophic group in the area) were the commonest food item for Achirus declivis.