Species diversity, distributions and conservation implications of Ichthyofauna of hill streams of Anamalai Tiger Reserve, Southern Western Ghats, India

Abstract

Abstract The increasing human accomplishments on inland waterways have an impact on species reduction and displacement worldwide. The study investigated the diversity, distribution, and conservation needs of freshwater fish in Anamalai Tiger Reserve, Southern Western Ghats, and was conducted from October 2012 to May 2019. It covers 53 sites, spread along the upstream and downstream parts of the Chalakudy river system and the Cauvery river system of Anamalai Tiger Reserve, and has documented a total of 69 species of fish belonging to 7 orders, 19 families, and 41 genera. Cypriniformes is the dominant order, with 23 genera and 44 species (63.7%), followed by the catfishes of the order Siluriformes, with 5 families, 5 genera, and 10 species (14.4%). Among the 69 recorded species, 33 are endemic, 34 are non-endemic to the Western Ghats, 3 are introduced exotic species, 1 is critically endangered (CR), 11 are endangered (EN), and 3 are vulnerable (VU) in IUCN red list categories. The result explains that species abundance, dominance, and richness are influenced by factors like altitude (68.832), area (7.049), and volume. Fish species richness and abundance showed a direct relationship with increasing stream order, with maximum values downstream in low-elevation regions. The Karuneer river site has the greatest number of threatened fish species and falls under an evergreen forest of undisturbed human pressure. Three exotic species were recorded from several sampling sites. Many of these species are under extreme pressure due to habitat changes and other human-induced impacts. Creating awareness about threatened species and the river system of Chalakudy and Cauvery upstream areas is needed to declare them fish sanctuaries for conserving the existing threatened species.