Journal of Environmental Biology

Interrelationship between physico-chemical characteristics of a tropical lake and their impact on biodiversity of planktons

Debashree Golder¹ and Sanjib Chattopadhyay^2*

¹Department of Zoology, B.K.C. College, Kolkata-700 108, India

²Bangabasi Evening College, Kolkata-700 009, India

*Corresponding Author E-mail: sanjib_chatt@rediffmail.com

Publication Data

Paper received:

14 August 2015 

Revised received:

25 January 2016 

Re-revised received:

29 March 2016 

Accepted:

10 May 2016

Abstract

The physicochemical parameters including temperature, pH, dissolved O2, free CO2, total alkalinity, permanent hardness, salinity, transparency, specific conductivity, BOD, COD, phosphate and nitrate were studied in a tropical lake, called Bonhooghly Lake (situated at Baranagar, Kolkata) around the year 2014 and the correlation between the said parameters, as well as their impact on Biodiversity indices were made. There is stable increase of CO2 content in water from August (27.24 mg l-1) and afterwards due to decaying of plant materials. Therefore there is a slight fall of pH (7.1). Significant negative correlation (p<0.01) between pH and CO2 content was also obtained. It also shows a significant negative correlation with O2 content as well. During February and March transparency of water falls significantly with the increase of algal bloom. It significantly decreases dissolved O2 content and pH but increases free dissolved CO2 (p<0.01). Phosphate has a definite correlation with nitrate content of the Lake, possibly because both are among the most essential nutrients of living system. Increase of one obviously indicates escalation of other. During the early months of the year phosphate and nitrate content of water increased steadily (up to 0.13 and 1.85 mg l-1 respectively) and a very high number of Chlamydomonas(up to15100 l-1) and Chlorella (up to 13140 l-1)were observed. Species richness indices (Menhinick's index) of Phytoplanktons were observed maximum in the month of May, dominance (Simpson's index) in January and diversity (Shannon-Weaver index) in April. Zooplanktons also followed the same trend indicating close interdependence. It was significant that apart from other factors, temperature played a most pivotal role in bringing the diversity in the plankton community.

 Key words

Physicochemical parameters, Correlation, Planktons, Simpson's index, Shannon-Weaver index

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