Effects of substratum type on fish assemblages in shallow areas of a tropical estuary

摘要: While there is already a comprehensive understanding of the effects environmental variables, such as dissolved oxygen, temperature and salinity, on structure, biomass metabolism aquatic biota in estuarine habitats, effect sedimentation, harmful underlying factor, remains unclear. The aim this study was to assess differences fish assemblages along freshwater salt water gradient large tropical estuary, evaluate them habitat disturbance associated with shallow sedimentation intertidal areas. Fish variables were recorded upper, middle lower salinity zones estuary at ebb tide both dry wet seasons. Sediment samples different levels analysed using granulometry, their organic content oxygen quantified. Water temperature, pH also measured. Habitat found be correlated density, richness assemblages. A total 77 species recorded, forming two distinct assemblages, Eleotridae family dominating upper zone, Gerreidae, Gobiidae Tetraodontidae most common estuary. Changes structure including reductions richness, natural features, where muddy sediment replaced by sandy quantity matter fell. Atherinella brasiliensis which showed preference for disturbed areas zones, while Dormitator maculatus They may taken indicators due sedimentation.