Volume No. 13 Issue No.: 02 Page No.: 160-168 October-December 2018

 

APPLICATION OF A BIOTIC INDEX TO ASSESS THE POL -LUTION LOAD OF THREE CONTRASTING WETLAN -DS USING THE MOLLUSCAN COMMUNITY WITH PHYSICOCHEMICAL WATER QUALITY

 

Bhattacharya Nandan*1 and Chakraborty S. K.2

1. UGC – Academic Staff College, Jadavpur University, Kolkata (INDIA)
2. Department of Zoology, Vidyasagar University, Midnapore, West Bengal, (INDIA)

 

Received on : July 29, 2018

 

ABSTRACT

 

An attempt has been made in the present paper to evaluate the three selected contrasting wetlands of Midnapore District, West Bengal, India. One of the selected wetlands received water from raw sewage from the iron factory ‘TATA Metallic’ in Midnapore District. The second one is located nearly hundred m. away from the first site and not under the threat of direct discharge of pollutants but facing subsoil seepage as well as aerial deposition. The rest one is away from any pollution impact and located at Midnapore town almost 7 km. away from the former two. A new physicochemical (Comprehensive Chemical Pollution Index or Pb) and a biotic index (Species Pollution Value or SPV and Community Pollution Value or CPV) has been applied in order to assess or evaluate the degree of pollution of the studied wetlands considering the molluscan community. All total 9 molluscan species have been identified of which 6 were in site I and 5 each for site II and III respectively. Maximum CPV was observed in site I followed by site II and III. Clear seasonal trend with regard to CPV was observed in site II and III exhibiting highest value during monsoon followed by premonsoon and postmonsoon. However, all the three wetlands exhibited a common trend having highest CPV during monsoon. The marked negative correlations were resulted between SPV and the seasonal density of the species populations, clearly indicating that pollution hindered the abundance. The results of two way ANOVA with regard to Pb showed significant spatial variation while CPV of three study sites in six seasons showed significant seasonal and spatial variations both. These observations indicated that macroinvertebrate community responded differentially to the pollution load in different seasons as well as the response was habitat specific also. On the basis of the implemented index Digniostoma pulchelle, Lymnaea luteola and Segmentina calatha can be recommended as pollution tolerant bioindicator species.

 

Keywords : Mollusca, Pollution, Biotic index, Wetland, Bioindicator

 

 

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