Chitralekha Sinha*
P.G. Department of Zoology, M.S. College, Motihari, B.R.A.B. University, Muzaffarpur, Bihar, India
Received : 08th April, 2024 ; Revised : 07th May, 2024
DOI:-https://doi.org/10.5281/zenodo.15009269
Abstract– Arthropods were the dominant group among macroinvertebrates, surpassing molluscs and annelids in abundance. Among arthropods, insects were the most dominant subgroup. In total, 85 species of macroinvertebrates were recorded in this study, classified into three major groups: arthropods, molluscs, and annelids. Arthropods occupied the highest position, comprising 66 species and accounting for 78.17% of the total. Molluscs followed with 11 species (12.64%), while annelids were the least represented, with 8 species (9.19%). Within arthropods, 66 species were identified, including 3 species of decapods. The insect subgroup was the most diverse, with 63 species. Among them, coleopterans (beetles) and hemipterans (true bugs) were equally dominant, each with 24 species. Odonates (dragonflies and damselflies) accounted for 8 species, dipterans (flies) for 4 species, and ephemeropterans (mayflies) for only 3 species. The density of arthropods varied throughout the year, ranging from 170 individuals per cubic meter in August to 980 individuals per cubic meter in February. Their population showed an increasing trend during winter and late monsoon and a decreasing trend during summer and early monsoon. Overall, macroinvertebrate populations were highest in winter, followed by summer and monsoon. The decline in summer is attributed to low water levels and the decomposition of macrophytes (aquatic plants). The monsoon decline is likely due to heavy rainfall, which disrupts habitats. In contrast, the winter increase is linked to the abundant growth of macrophytes, which provide shelter, food, and diverse spawning sites. The biotic index of insects suggests that the water quality is fair, with minor disturbances. The highest monthly and daily net production of aquatic insects was observed during summer and monsoon, while negative growth was recorded during the post-monsoon and winter months.
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