author(s)
Partha Pratim Chakravorty, Monalisa Sinha and Susanta Kumar Chakraborty

abstract
A study on the impact of industrial effluent discharge on the distribution and biodiversity of benthic macro-invertebrates and water quality of a fresh water pond, in Gokulpur, West Bengal, India near Tata metaliks (a metal refinery) was carried out during April 2009-March 2010. Two ponds were chosen for this study of which one was used as control. Comparing the physico-chemical parameters in two ponds it was seen that pond G had higher hardness, total suspended solid, pH, phosphate, hydrogen sulphide, cyanide, heavy metals like lead, cadmium and mercury. The total no of macro-benthic taxa and their overall richness indices and diversity indices were higher at pond in Santipukur, (44 taxa) than pondin Gokulpur (22 taxa). The pond S was dominated by Ephemeroptera, Hemiptera where as other order found in small quantities included Coleoptera, Diptera, Molluscs, Crustacea and Odonata. On the other hand pond G was mainly dominated by tolerant Diptera and Hemiptera. The relationship between physico-chemical parameter and macrobenthic data were investigated by Pearson correlation analysis .This statistical analysis showed that richness and diversity indices in pond G were mainly influenced by water hardness, total suspended solid, phosphate, hydrogen sulphide, lead and cyanide. It was also seen that a lot of species that were present in pond S were absent in pond G. CCA ordination biplot showed the presence of benthic macro-invertebrates in pond G was due to their strong and positive correlation with environmental variables.