Environmental Factors Associated with Fish Diversity in Two Tributaries of River Chittar, Southern Western Ghats, Tamil Nadu, India

In the present research, we examined Ichthyofaunal diversity, habitat preferences, and environmental variables in the Chittar River tributaries in Tamilnadu, India. The species composition is comprised of 14 species representing 4 orders, 6 families, and 12 genera. Cyprinids were the most abundant group in the assemblage composition of fishes, which was approximately 61.5%-83.33%. According to the Shannon-diversity index of fish populations in the study streams, the upstream of New Falls and the Harihara river reveal a high species richness. Among the recorded fish species, Puntius arenatus, belonging to the family Cyprinidae, is in the vulnerable categories of the IUCN List. However, the fish species exhibited a higher density in the headwaters upstream and the density decreased in the downstream. However, bedrock and boulders were observed as the predominant substrates in upstreams (sites 1 and 3) throughout the seasons. The results of Principal Component analysis of water quality factors and fish abundance and species richness revealed that dissolved oxygen, total hardness, and alkalinity have less impact on fish abundance, whereas TDS and conductivity had a substantial correlation in all downstreams. Fish were influenced by a diverse natural and anthropogenic longitudinal pattern, as well as regional disturbances induced by adjacent land users.