Diversity of Macroinvertebrates in the River Kankai, Eastern Nepal

Abstract

The River Kankai in eastern Nepal, shaped by various human activities, presents a significant opportunity to examine freshwater macroinvertebrate diversity, which indicates ecosystem health and environmental conditions. This study aims to investigate the macroinvertebrate diversity of the River Kankai. Macroinvertebrate species were collected using plankton nets, gloves, and forceps from January 2023 to December 2024 across six sampling stations, identifying 20 species. The assemblage was dominated by Arthropoda (13 species), followed by Mollusca (5 species) and Annelida (2 species). Diversity indices, such as Shannon-Wiener, Simpson, and Margalef, revealed spatial variations: while species evenness increased downstream, species richness declined, likely due to anthropogenic pressures such as irrigation, hydropower, and cultural practices. One-way analysis of variance (ANOVA) indicated no significant differences (p < 0.05) in diversity indices among the sampling stations. Principal Component Analysis (PCA) identified environmental gradients and site-specific factors influencing biodiversity. The high inter-station correlation (r > 0.99) suggested consistent environmental influences, although unique diversity patterns were observed upstream. Arthropods, the dominant group, displayed adaptability to a range of ecological conditions, while molluscs and annelids indicated the presence of less disturbed habitats. The findings underscore the importance of targeted conservation efforts, including pollution control, habitat restoration, and community engagement, to protect biodiversity and inform policy development. This pioneering research establishes baseline data for the long-term monitoring and management of the River Kankai’s ecosystem, serving as a reference point for riverine biodiversity studies in Nepal. Future research should focus on integrating molecular and functional diversity to enhance understanding of ecosystem dynamics and resilience.