Spatial Distribution Patterns and Beta Diversity of Fish Communities in a Tropical River Basin of Deccan Plateau

Riverine ecosystems exhibit significant spatial variations in their communities, and understanding of these variances is vital to comprehend the mechanisms that maintain biodiversity. This study was conducted to understand pattern of distribution and beta diversity of fish communities in the Bhima River basin in the Deccan Plateau region of India. Fish distribution data from 59 sites across 11 rivers of the Bhima River basin were collected, and pair-wise beta(Dissimilarity) and site-wise local contribution to beta diversity (LC beta D-Sorensen) and its components (LC beta D-Turnover and LC beta D-Nestedness) were calculated. Power function regression was analysed to understand the decay in community similarity with geographical and environmental distances. Redundancy analysis was performed to investigate the relationship between fish distribution and environmental variables. Results indicated that species richness declined with increasing longitude from west to east. A negative relationship was observed between species richness and LC beta D-Sorensen. LC beta D-Turnover formed boolean AND-shaped curve at both ends of the species richness gradient, while LC beta D-Nestedness values exhibited boolean OR-shaped curve. No significant difference between mean LC beta D-Turnover and mean LC beta D-Nestedness across the sites was observed. The distance decay relationship between community similarity and both geographical and environmental distances follows the power law shape, and the slope of this relationship flattened with increasing distance. Precipitation, topography, temperature variation and dissolved oxygen played a pivotal role in shaping fish assemblages. This study provides insight into the spatial distribution of fish communities in the Bhima River basin, which will be helpful to comprehend the ordination of biodiversity in the riverine ecosystem of the Deccan Plateau region.