International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 12, December 2014 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Diversity of Cyanophyceae in the Mirik Lake of Darjeeling Himalaya, India Debashri Mondal 1 , Joydeb Pal 2 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 Abstract: The present investigation was carried out for two years from October, 2010 to September, 2012 to study the Cyanophycean diversity in Mirik Lake of Darjeeling Himalaya, West Bengal, India. During the whole study period a total of eleven genera of Cyanophyceae were recorded, of which Spirulina sp., Arthrospira sp. and Anacystis sp. were found to be most frequent. The density varied from 33 to 1844/ml and the highest diversity was recorded at the point where waste water entering into the lake mainly from the market area. Keywords: Cyanophyceae, Mirik Lake, density, diversity 1. Introduction Cyanophyceae are colonizing microorganisms that are found throughout the world. They are oxygenic photosynthetic and some of them are able to fix atmospheric nitrogen. Ecologists started giving them importance as primary producers and realized that without them no animal population exists. Cyanophyceae are by far the largest group of photosynthetic prokaryotes as judged by their widespread occurrence, frequency, abundance and morphological diversity. During the recent past, studies on Cyanophyceae have emphasized their important role in ecosystem. They grow at any place and in any environment where moisture and sunlight are available. However, specific algae grow in specific environment and therefore their distributional pattern, ecology, periodicity, qualitative and quantitative occurrence differ widely 1 . The Cyanophycean density and diversity of surface waters of various fresh water bodies have been studied by a number of investigators 1 2, 3, 4 . However a very few literature 5,6 has been found on the study of the plankton communities of freshwater bodies of Darjeeling Himalaya like Mirik Lake. Till date the density and diversity of Cyanophyceae population in the Mirik Lake was not reported elsewhere. Thus the present study was done to find out the density and diversity of Cyanophyceae in Mirik Lake of Darjeeling Himalaya. 2. Materials and Methods “Sumendu Lake” which is popularly known as “Mirik Lake” is an artificial reservoir of Mirik Town, the famous hill resort in the Kurseang subdivision of Darjeeling Himalaya at an altitude of 1767 meters. It extends between 26 0 53 ' N and 88 0 10 ′ E. The lake was constructed in 1979 under “Mirik Tourist Project” for the facilitation of commercial tourism in Darjeeling. This lake has been included under National Lake Conservation Programme, formulated by the Ministry of Environment and Forests, Government of India. The lake covers an area of about 16.19 ha with approximate length of 1.25 km and the peripheral road is about 3.5 km. The arch-type over bridge across the lake is 24.38 m long. The maximum and minimum depths of the lake were recorded to be 7.92m and 1.83 m 7 respectively at the initial stage. The lake is fed by both perennial streams and rainwater. Since the lake is situated in a valley encircled by hill ridges with extensive natural drainage network, it receives wastewater from human settlements through numerous inlets. There is one out-fall point through which the spillover water of the lake is discharged into the river Mechi, situated to the Western side of the lake. The catchment area consists of residential areas, vacant lands and commercial centers comprising of hotels, restaurants and other shops. Mirik Lake and its surroundings, as a whole, contain multifarious recreational features like boating, jogging, organizing fair, picnic and many others. This is the most beautiful lake of Darjeeling district where visitors come from different parts of the world. Besides attracting tourists, the lake water also serves as a major source of drinking water to the local people. Density and diversity of Cyanophyceae collected from the surface water samples of Mirik Lake was studied for two years from October 2010 to September 2012. Seven sampling points were identified in the Lake considering the length of the lake as well as point and non-point sources of pollution. All the sampling points are shown in figure-1. Monthly basis sampling was done from these sites with the help of paddle-boat. The brief descriptions of the sites (S-1 to S-7) are as follows: S-1 (26 0 53 ' 08.49 " N and 88 0 11 ' 08.32 " E): This site is situated at the point where wastes from hotels and residential area join into the lake. Car washing also takes place at this site. S-2 (26 0 53 ' 16.80 " N and 88 0 11 ' 14.95 " E): It is located at the flank of the lake where tourists assemble to observe the fishes that agglomerate specifically here for consuming various food items thrown by the visitors. Wastes from hotels and residential areas also join at this site. Paper ID: SUB14961 2080