KAMAL CHOUDHURY AND SIKHA RANI KALITA
Abstract
The present investigation deals with the seasonal variations in physico-chemical characteristics and abundance of zooplankton population in Dora Beel, Kamrup District of Assam. The survey was undertaken from March, 2022 - February, 2023 and done in four different seasons viz. Monsoon, Pre-monsoon, winter and post-monsoon. The physico-chemical studies include the seasonal study of water temperatures, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), pH and Free Carbon dioxide (CO2). The result of water analysis reveals that in winter season water temperature and free CO2 were minimum but dissolved oxygen was maximum. In the monsoon season water temperature and BOD were maximum but DO was in minimum level. Free carbon dioxide was maximum but BOD was minimum in post-monsoon. The pH level was minimum in pre-monsoon season and maximum in post-monsoon. A total 24 numbers of zooplankton species were recorded belonging to five different planktonic groups such as Protozoa, Rotifera, Cladocera, Ostracoda and Copepoda. The post-monsoon season observe as peak abundance season for all the zooplanktons and pre-monsoon as low abundance season. Protozoa is the dominant group (based on abundance) followed by Rotifera, Cladocera and Copepoda. But the number of species was highest in Rotifera group. The Copepoda and Ostracoda were the lowest abundant group.