To Determine the Structure and Function of Bhagar Oxbow Lake in Dumraon, Buxar, South Bihar, India

The paper deals with the structure, function, and fisheries resources of Bhagar lake, South Bihar, one of the oxbow lakes in Dumraon (un-reported and un-described), from February 2018 to January 2020 under the state non plan research project. This lake is spread from Nauki par (Chakki) to Nainijore (Brahampur), Dumraon, (Buxar) with a large size wetland in dimension of 20 km length & 1 km width. Bhagar oxbow lake is U shaped, hydrological closed lentic type meander of the Ganga river, it is fed by the monsoon runoff and ingress of flood water from the river Dharmawati. The water depth of lake ranges between 1.5 to 3 meters in summer and depth 4 to 6 meters during the Monsoon months. Water temperature ranged from 16°C (January) to 30°C (August) whereas the pH value of lake water was found within 7.0 to 7.8. In aspect of biological properties of the lake, it was highly infested with submerged vegetation with dominancy of Hydrilla cillata and floating aquatic weeds (water hyacinth) such as Eichhormia crassipes with approximately 30 percent area coverage. This lake is rich sources of fishes with identified forty four species with example of annual fishes like Mystus spp., Puntius spp., Channa spp., Carps spp., small Macrobrachium spp. and several seasonal fishes, providing livelihood support to more than sixty five household, socio-cultural importance. It also gives protection to many wild mammals like Blackbucks (Antelope cervicapra), swamp deer (Rucervus duvaucelii) and Nilgai (Boselaphus tragocamelus) during summer time. This lake is also wintering ground of the migratory birds such as Heron and Crane.