Available online at www.pelagiaresearchlibrary.com Pelagia Research Library European Journal of Experimental Biology, 2012, 2 (5):1451-1456 ISSN: 2248 –9215 CODEN (USA): EJEBAU 1451 Pelagia Research Library Rotifer diversity of Mirik Lake in Darjeeling Himalaya Debashri Mondal 1 , Joydeb Pal 2 , Tarun Kanti Ghosh 3 and Arun Kanti Biswas 4 1 Department of Zoology, Raiganj Surendranath Mahavidyalaya, University of Gaur Banga, Raiganj- 733134, West Bengal, India 2 Departmentment of Zoology, University of North Bengal, Siliguri-734013, West Bengal, India 3 Environmental Impact and Risk Assessment Division, National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur-440020, India 4 NEERI Kolkata Zonal Laboratory, 1-8, Sector C, East Kolkata Area Development Project, East Kolkata Township, Kolkata-700107, India _____________________________________________________________________________________________ ABSTRACT Rotifer diversity was studied in Mirik Lake, Darjeeling Himalaya, for a period of two years during October, 2005 to September, 2007 from the surface water samples of seven selected sampling locations. A total of seventeen varieties of rotifers were recorded during the whole study period, of which Asplancha sp. and Brachionus sp. were the most common genera in the lake. While the density varied from 24 to 8530/m 3 it was relatively higher during summer months. The highest diversity was recorded at sampling location 6. Key words: Rotifer, Mirik Lake, density, diversity _____________________________________________________________________________________________ INTRODUCTION Rotifers are important ecological group occupying a wide range of habitats in aquatic ecosystem [1]. They are first order consumers drawing energy directly from primary producers of the ecosystem, viz., phytoplankton, and in turn form the food of a large number of planktivorous fishes and other invertebrates and thereby help in transferring energy to higher trophic levels. Thus population of rotifer is sensitive indicators of aquatic ecosystem. Rotifer diversity has been studied by various workers in different freshwater bodies of India [2, 3, and 4]. However, study on rotifer diversity in the freshwater bodies of Darjeeling Himalaya is scanty. Till now there is no report found on rotifer diversity of Mirik Lake of Darjeeling Himalaya. Therefore the present investigation was aimed at finding out the diversity in Mirik Lake of Darjeeling Himalaya. MATERIALS AND METHODS Study site Mirik is one of the famous hill resorts in the Darjeeling Himalaya at an altitude of 1767 meters. It extends between 26 0 53 ' N and 88 0 10 ′ E and covers an area of 135.9 ha. “Sumendu Lake” or “Mirik Lake” is an artificial reservoir of