ABSTRACT

Zooplanktons are the grazers on a freshwater ecosystem. The present study was conducted in five stations of the tail race of River Dikhow, a southern tributary of River Brahmaputra, to establish a relationship of water quality of the river with the zooplankton diversity. Collected samples of zooplankton were identified using standard references. A total of 10 zooplankton species belonging to four classes (Cladocera, Copepoda, Rotifera and Protozoa) were recorded. The diversity of the zooplankton indicated that Cladocera and Copepoda were dominant groups in the tail race of the Dikhow River with 33.54 % and 30.32% respectively. The percentage composition was found to be least for Protozoa with 7.74 %. The detailed aspects of monthly variation along with percentage composition of zooplankton species recorded during the study are discussed herein. Abundance of Cladocera and Copepoda may be indication of organic pollution level in the river.

Key words: Zooplankton, freshwater, ecosystem, Cladocera, Copepoda, pollution