Phytoplankton species composition and seasonal changes were investigated in the Bhoj wetland Bhopal. Taxonomic composition, diversity, and abundance of phytoplankton were studied at nine stations from March 2008 to February 2010, in relation to various physico-chemical factors. Total phytoplankton species composition in the Bhoj wetland was represented by 360 species. Among phytoplankton, diversity belonged to seven groups. Chlorophyceae was the dominant group (48%) followed by Bacillariophyceae (26%), Cyanophyceae (15%), and Euglenophyceae (9%), while Pyrophyceae, Chrysophyceae, and Xanthophyceae contributed 2% of the population. Phytoplankton on the basis of seasonal studies recorded 1651 units l(-1) during summer season which was contributed mainly by Chlorophyceae (39.3%), with Spirogyra sp. (14.2%) and Closteriopsis sp. (9.1%) contributing maximum to the total group in the first year, while during the second year of summer period, a total of 2095 units l(-1) was recorded which was contributed mainly by group Pyrophyceae (51%) with the main dominant species represented by Ceratium hirundinella (98.46%). The highest Shannon-Wiener diversity index (H') value (4.27) was recorded. Simpson values are approaching 1, signifying that sites have high relative diversity due to its supporting surrounding components. The trend of variation in evenness values was more or less the same as Shannon diversity index. Thus, the highest diversity indices recoded at all the stations in the present study justify the diverse nature of species inhabiting the different ecological niches in the ecosystem. The very high phosphate and nitrate concentrations in the wetland are indicators of pollution which may be due to the discharge of agricultural and sewage wastes enriched with nutrients as well as the human activities there. Our recommendation is to avoid as far as possible the discharge of sewage and agriculture wastes into the Bhoj wetland. The effects of various physicochemical water quality parameters on the seasonal distribution and succession of the above mentioned phytoplankton population as well as the interaction and eutrophication are discussed.

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The aim of the present study was to determine the species diversity and abundance of net zooplankton in samples collected from Bhoj wetland, Bhopal, India. A total of 82 species of zooplankton were identified, among them, 66 species were recorded during the first year (2008-09) and 70 species were documented during the second year (2009-10) of the study period. In the first year, Rotifera recorded the highest number of species (53%) followed by Cladocera (29%), which in turn was followed by Copepoda (8%), Protozoa (6%) and Ostracoda (5%) in the second year of study, Rotifera recorded the highest number of species (47%) followed by Cladocera (37%), which in turn was followed by Protozoa (7%), Copepoda (6%) and Ostracoda (3%). Cumulative 24 months density in the present study ranged from 760 to 11050 Ind.l -1 , with an overall mean of 3307 Ind.l -1 . A major peak of 11050 Ind.l -1 was observed in June 2009, with 47 and 43% contribution from Copepoda and Rotifera. Among Copepoda, Cyclops sp. and nauplii were major contributors to this peak while amongst Rotifera, Brachionus caudatus and Keratella tropica were dominant contributors. Cladocera was comparatively less represented group, being chiefly represented by Diaphanosoma sp. Shannon-index ranged between 0.96 and 2.75 during the two years of study period.

In order to assess the effect of dredging on macrozoobenthos community, study was carried out in the Hazratbal Basin of Dal Lake from August 2010 to January 2011. The results showed strongly significant differences (P<0.05) between control site and the site which was sampled after dredging operation. The significant differences were also found between pre-dredging and post-dredging (P = 0.004), while as, there were no significant differences between control site and pre-dredged site (P = 0.191). Altogether 6 taxa were observed at post dredged site in comparison to the pre-dredged (9 taxa) and the control site (10 taxa). At control site, molluscans were found to be the dominant group (1255 ind/m 2) followed by annelida (1110 ind/m 2) and diptera (330 ind/m 2), There were six taxa were shared both sites (control, impact sites) and one taxa Erpobdella octoculata of annelida was only restricted to control site. The abundance of most taxa were significantly higher at control and pre-dredged site. Three species (Lymnea stagnalis, Radix auricularia and Radix ovata) were completely eliminated after dredging operation. A cluster analysis showed that macrozoobenthic communities revaealed 90% similarity levels between control site and pre-dredged site. After dredging similarity level was greatly declined and was recovered 76% after six months of dredging.

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