Aquatic Beetle (Coleoptera) assemblages and their relationship with water quality variations across freshwater habitats in Bankura District, West Bengal, India

This study, conducted across 26 sites in Bankura district, West Bengal—a region that forms a transitional zone between the plains of Bengal and the Chota Nagpur plateau—aimed to document the diversity, distribution, and richness of aquatic beetle species, as well as to assess key water quality parameters. Sampling was carried out using a D-shaped aquatic insect collecting net between February 2024 and March 2025, and water quality was evaluated by measuring pH, Total Dissolved Solutes (TDS), and Electrical Conductivity (EC). A total of 33 species belonging to five families were recorded, with the family Dytiscidae (15) showing the highest species richness, followed by Hydrophilidae (13), Noteridae (3), Gyrinidae (1), and Haliplidae (1). Canthydrus laetabilis (92.3%)was identified as the most abundant species among the assemblages, whereas Dineutusindicusindicus (2.03%) was recorded as the least abundant. Results indicated that sites with moderate pH (pH 6) and lower TDS (22 ppm) levels supported higher species richness, while higher pH (pH 11) and TDS (249 ppm) were associated with a marked decline in species diversity. Multivariate analyses, including PERMANOVA (pseudo-F = 3.25, p < 0.01, R² = 0.25) and PCA, confirmed that water quality parameters significantly structure these communities, as evidenced by distinct site clusters associated with varying water chemistry. Overall, the findings highlight the complex interplay between environmental factors and aquatic beetle assemblages, emphasizing the need for integrated water quality management to preserve freshwater biodiversity in the context of climatic and anthropogenic changes.