Acetylcholinesterase activities in marine snail (Cronia contracta) as a biomarker of neurotoxic contaminants along the Goa coast, West coast of India

The measurement of acetylcholinesterase (AChE) activity is used worldwide as a biomarker of environmental contamination due to neurotoxic substances. In the present study the AChE activities was measured in marine snails (Cronia contracta) collected seasonally from six sampling sites (viz. Arambol, Anjuna, Dona Paula, Vasco, Velsao and Palolem) along the Goa coast during the pre-monsoon (April, 2004), monsoon (September, 2004) and post-monsoon (November, 2004) periods. The AChE activities in C. contracta showed wide variation along the Goa coast. It was found to be quite high at the reference site, Palolem (23.97, 21.72 and 24.85) throughout the sampling period (April-November, 2004). The AChE activities in C. contracta decreased significantly at Vasco (44.6-52.4% reduction) followed by Dona Paula (24.9-36.2% reduction), Velasao (10.8-35.9% reduction), Arambol (12.6-37.3% reduction) and Anjuna (0-12.7% reduction). Such a significant variation of AChE activities in the marine snail along the Goa coast can be attributed to neurotoxic substances prevalent in those regions. The high concentration of different neurotoxic metals (lead, cadmium, copper, manganese and iron) and petroleum hydrocarbons in the tissues of the marine snails at Dona Paula, Vasco and Velsao clearly substantiate reduction of AChE activities in C. contracta. The in vitro studies on the inhibition of AChE by different metals and PHC indicated that lead, cadmium and copper are the most predominant inhibitor. Based on the AChE activities in C. contracta the sampling sites along the Goa coast can be classified into three major clusters such as highly contaminated sites (Dona Paula, Vasco and Velsao), moderately contaminated sites (Arambol, Anjuna) and least contaminated site (Palolem).