Aquatic insect community of River Brahmaputra near Dibru Saikhowa National Park, Assam, North East India

Abstract

A seasonal study was conducted on aquatic insect community of Brahmaputra River at three sites, Balijan ghat (BS1), Oakland (BS2) and Maijan ghat (BS3) of Dibrugarh district after its confluence with Dibru River near Dibru Saikhowa National Park. The sampling of insects and water was done in replicates during September 2014 to 2015. The study recorded 4 orders, 10 families, 12 genera and 12 species of aquatic insects. Highest density of order Hemiptera was found across the sites and seasons. Seasonal variations of environmental variables of water were found moderate. Density of aquatic insects showed significant negative relationship with Electrical conductivity, Total dissolved solid and Rainfall. The study revealed low Shannon Weiner Diversity Index values of aquatic insects (Shanon H՛< 1) in all the sites indicating perturbed condition of the water. Canonical Correspondence Analysis (CCA) showed that the species environment correlations of axis 1 and axis 2 were high and some of the species responded negatively to total alkalinity. This study though of preliminary nature contributed to the knowledge of faunal diversity of the area around Dibru Saikhowa National park.