Spatio-temporal variation of the zooplankton community in a tropical wetland (Bhoj Wetland), Bhopal, India

Bhopal, the capital city of the state of Madhya Pradesh, India is famous for its numerous lakes. The Bhoj Wetland is a wetland of international importance (Ramsar Site). In the two years of study period, a total of 82 zooplankton species were recorded from February 2008-January 2010. Out of which 66 species were recorded in the 1st year (2008-2009), and 70 species documented during the 2nd year (2009-2010). The zooplankton population belongs to five major groups namely: Rotifera (46%), followed by Cladocera (34%), Protozoa (10%) and Copepoda and Ostracoda contributing 6 and 4%, respectively. With regards to Rotifera, in the major peak of June 2009 (38 species), was dominated by the various species of Brachionus and Keratella. The population density data revealed that cumulative site mean density ranged from 84 to 1579 Ind. l-1, with an overall mean of 399 Ind. l-1. The 24 months of mean site density indicated a major peak of 1579 Ind. l-1, in June 2009, with 47 and 43% contribution from Copepoda and Rotifera. However, among Copepoda, Cyclops and Nauplius larvae were major contributors to this peak and among Rotifera, Brachionus caudatus and Keratella tropica were dominant contributors. The comparative cumulative mean data on zooplankton in Bhoj Wetland indicate that during the 1st year, the diversity was 31 species and 30 species in the 2nd year. The mean density, during the 1styear was 276 Ind.l-1 that increased to 468 Ind.l-1 in the 2nd year. This variation in density during two years may be attributed low water volume caused by drought conditions in the second year. Bhoj wetland is under eutrophic state as a result of human stress in the catchment area. Further, increase of plant nutrients in the wetland waters is deteriorating its ecological condition.Hence, it is imperative to focus on preservation of these endangered habitats to achieve ecological sustainability.   Key words: Zooplankton, diversity, density, indicator species, BhojWetland.