Temporal Patterns in Fish Community Structure: Environmental Perturbations from a Well-Mixed Tropical Estuary

The composition of fish communities in tropical coastal ecosystems is regulated by seasonal patterns in the oceanographic environment. In the present study, the authors have studied the temporal variation of fish assemblages and environmental variables in a tropical coastal ecosystem, Zuari estuary in Goa located along the west coast of India. The species abundance and environmental data were subjected to multivariate analysis (canonical correspondence analysis and non-metric multidimensional scaling) and showed seasonal differences in fish communities. The second canonical axis was loaded with salinity, temperature, dissolved oxygen, transparency and depth separating the seasons into discrete groupings. The authors also found that the species diversity is significantly less during the monsoon season in comparison to pre- and post-monsoon seasons. Moreover, season-specific diagnostic species were identified using SIMPER analysis. The seasonal migration of species mediated by environmental factors seems to be an important element which determines the temporal pattern in fish communities. The results of the study have implications on fish diversity, conservation and coastal fisheries management.