Ecosystem Health of Lake Tamrangabeel, Bongaigaon District, Assam, India with Special Reference to Aquatic Insect Assemblage

This study investigated the ecosystem health of a floodplain lake, Tamrangabeel of Bongaigaon district, Assam, India using aquatic insects as bioindicator. The aquatic community of Tamrangabeel was represented by 37 species belonging to 19 families and 5 orders. Shannon –Wiener diversity index (Shannon H') values were recorded less than 1 in all the sites of the lake which indicated perturbed condition of the lake. Order Hemiptera was found to be the largest order with highest number of species. Eudominant species recorded in this lake were Micronecta siva (order Hemiptera) and Cloeon sp. (order Ephemeroptera). Biological Monitoring Working Party (BMWP) Score, Average Score per taxon (ASPT), and Stream Invertebrate Grade Number-Average Level (SIGNAL) Score reported from the study reflected good ecological potential as well as slightly impacted nature of the water body. The values of different environmental variables of water of all the sites of the lake were found conducive for aquatic life. This study provided an early warning of perturbation of the lake which is to be addressed before it is too late.