Characterization of fish community structure and an estuarine fish community index for temporarily closed estuaries (TCEs) from India's south-western coast

We present for the first time, data on fish assemblage structure for ten temporarily closed estuaries (TCEs) along the south-western coast of India. Fish community structure differed significantly between TCEs based on species presence/absence, estuarine use and feeding mode. Marine migrant and freshwater stragglers dominated the 'fish guilds', while piscivores and zoobenthivores were the major feeding guilds, in all estuaries. We used the Estuarine Fish Community Index (EFCI) and a Combined Anthropogenic Pressure Index (CPI) to determine the ecological quality of TCEs. The application of functional guilds and EFCI successfully represented the use of TCEs by fish communities, and also the functional similarities existing between fish assemblages of these estuaries, despite considerable taxonomic, physical and chemical differences. EFCI indicated that the ecological health of TCEs in south-western India ranges from 'poor' to 'good'. We also established a significant relationship between CPI, EFCI and ecological quality in various TCEs using the Generalized Linear Model (GLM).

Automated summary

This study presents, for the first time, data on the fish assemblage structure of ten temporarily closed estuaries (TCEs) along the south-western coast of India. The findings indicate significant differences in fish community structure among the TCEs based on species presence/absence, estuarine use, and feeding mode. The use of functional guilds and the Estuarine Fish Community Index (EFCI) successfully represent the ecological quality of TCEs, revealing functional similarities between fish assemblages despite taxonomic, physical, and chemical differences. The study also establishes a significant relationship between anthropogenic pressure, EFCI, and ecological quality of the TCEs using the Generalized Linear Model (GLM).