Macroinvertebrates Diversity and Seasonal Dynamics in the Streams of Southwest Bhutan: Preliminary Findings and Implications for Future Research

Abstract

Traditionally, assessing stream and river health in the Hindu Kush-Himalayan (HKH) region has relied primarily on physical and chemical data, which offer limited insights into aquatic ecosystems. The recent Assessment System to Evaluate the Ecological Status of Rivers in the Hindu Kush-Himalayan region (ASSESS-HKH) project marks a significant advancement by developing robust bio-assessment tools. This initiative was crucial for addressing the region’s unique ecological challenges, characterized by its rich biodiversity and essential freshwater resources. In Bhutan, however, the use of macroinvertebrates as bioindicators for water quality assessment has been limited. This study aimed to enhance stream health evaluation in southwest Bhutan by utilizing macroinvertebrates. Two representative streams were sampled using detailed techniques, revealing a diverse range of macroinvertebrate families - 39 families in one stream and 34 in the other - with notable variations in abundance among key taxa. Seasonal changes in community composition reflected ecological dynamics influenced by factors such as water temperature, flow regime, and substrate composition. HKH biotic scores indicated minimal stream impairment. The study highlights the need for sustainable monitoring and management of stream health in southwest Bhutan. Future research should investigate the effects of monsoonal patterns on macroinvertebrate diversity, conduct long-term monitoring, and assess the impact of anthropogenic activities to further refine conservation strategies.