Towards building conservation prioritization strategies for tropical freshwater systems: A case study based on fish assemblages from the Western Ghats, India

Abstract

Freshwater ecosystems of the Western Ghats (comprised primarily of rivers, lakes, and wetlands; less than 0.01% of the total water on Earth) harbor diverse communities of flora and fauna which are among the most threatened in the world. It is projected that habitat loss will lead to significant decline in freshwater fish diversity. Many rivers that are expected to lose fish species are located in tropical and sub-tropical countries. The freshwater diversity of the Western Ghats (one of the global biodiversity hotspots) is particularly vulnerable to recent expansion of human population and development in the region. The present study is an example of how baseline data on fish assemblages in disturbed and undisturbed river systems of the Western Ghats can be employed in developing conservation prioritization plans for tropical river systems. Analyses of beta diversity patterns along river gradients indicated the sensitivity of species turnover to altered habitats and polluting industries near study sites. Null model analyses was used to investigate assemblage structure across disturbed and undisturbed sites on the rivers, which revealed that structure of species co-occurrences depended on the extent of human disturbance in the rivers. A method of ranking based on the Index of Biotic Integrity (IBI) was used to categorize disturbance levels of different sites. A combination of approaches of assemblage structure together with ranking of the IBI will help in developing conservation strategies for the region and prioritization plans for management at local and regional scales.