Journal of Environmental Biology

Aquatic insect community of lake, Phulbari anua  in Cachar,

Assam

 

Susmita Gupta* and Rupali Narzary

Department of Ecology & Environmental Science, Assam University, Silchar-788 011, India

*Corresponding Author email : susmita.au@gmail.com

 

 

 

 

Publication Data

Paper received:

02 December 2011

 

Revised received:

17 May 2012

 

Accepted:

26 July 2012

 

Abstract

An investigation on the water quality and aquatic insect community of an oxbow lake (Phulbari anua) of south Assam, North-East India was carried out during February to April, 2010. Aquatic insect community of the oxbow lake was represented by 9 species belonging to 9 families and 4 orders during the study period. Order Ephemeroptera and Hemiptera were found to be dominant. Record of 5 species and 5 families from the order Hemiptera showed that this is the largest order in terms of aquatic insect diversity of the lake. Computation of dominance status of different species of aquatic insects of the lake based on Engelmann’s Scale revealed that Anisops lundbladiana and Cloeon sp. were eudominant in the system. The Shannon- Weiner’s Diversity Index (H’) and Shannon  evenness values (J’) were found to range from 0.3-0.69 and 0.53 -0.97, respectively indicating perturbation of the system. Again in terms of physico-chemical properties of water the lake is in a satisfactory condition where all the parameters are well within the range of IS 10500. The DO values were found to range from 6.8 to14.8 mgl^-1. Free CO₂ fluctuated from 1 to 4.98 mgl^-1 and nitrate in water ranged from 0.4 to 2.1 mgl^-1. Margalef’s water quality index values of most of the samplings also indicated clean water condition of the lake. Correlation coefficient analyses of the environmental variables, aquatic insect diversity and density of the lake revealed that aquatic insect diversity of the lake is mainly governed by dissolved oxygen, nitrate, and free carbon dioxide.

 

Key words

Oxbow lake, Hemiptera, Ephemeroptera, Diversity, Density

 

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