Int.J.Curr.Microbiol.App.Sci (2018) 7(7): 2700-2715 2700 Original Research Article https://doi.org/10.20546/ijcmas.2018.707.317 Ecological Assessment of Hooghly - Bhagirathi River System through the Study of Diversity of Bivalves and Gastropods in Relation to Physico-Chemical Parameters Bhuban Mohan Majhi 1 , Ashim Kumar Nath 2* , Chiranjeeb Dey 1 , Ayan Mondal 3 and Nimai Chandra Saha 4 1 Department of Zoology, Serampore College, Serampore, Hooghly, West Bengal, India 2 Department of Zoology, Sidho-Kanho-Birsha University, Purulia, West Bengal, India 3 Department of Environmental Science, University of Burdwan, West Bengal, India 4 Vice Chancellor, University of Burdwan, West Bengal, India *Corresponding author ABSTRACT Introduction In the world, fresh water ecosystem is being subjected to unexpected level of anthropogenic disturbance (Loh et al., 1998). In the developing countries pollution of surface water as well as ground water is a major problem (Yan et al., 2015). For biological monitoring and risk assessment molluscs are used as indicator organism (Goldberg and Edward, 1986) because of their wide range of distribution and high adaptability. They react sharply to environmental change which makes them very suitable for studies of relationship between organism and environment (Ustaoğlu et al., International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 07 (2018) Journal homepage: http://www.ijcmas.com It is generally considered that benthic organisms are good indicator of environmental condition of aquatic ecosystem. Present study focused on seasonal distribution of macrobenthic fauna and physico-chemical parameters of Hooghly-Bhagirathi river (part of Ganga river) during one year from June 2016 to May 2017. Total 16 species of mollusks (11 species of gastropods belonging to seven families and 4 species of bivalves belonging to the three families) have been found during study period. Among them Tarebia lineata, Filopaludina bengalensis, Novaculina gangetica and Lamellidens marginalis are found to be the most dominant species of the studied region of Ganga river. Four stations had been selected for the purpose of study (Station 1: Nabadwip, Station 2: Mayapur, Station 3: Khardaha, Station 4: Raichak) along the entire stretch of studied river. Gastropod and bivalves represent 43.59% and 56.41% of the total molluscs respectively. Principle component analysis (PCA) was done to determine the relationship among molluscan fauna and physico chemical variables of water. General linear model (GLM) was also done which gives a satisfactory result. Rarefraction curves confirmed the low probability of finding of addition of new species in station-1, whereas the probability of finding new species in case of station-2, station-3, station-4 are very low. Keywords Gastropod, Bivalve, Physico-chemical parameters, Principle component analysis, General linear model Accepted: 20 June 2018 Available Online: 10 July 2018 Article Info