ABSTRACT
The paper describes differential tolerance of two fresh water crustaceans Mesocyclops hyalinus and Allodiaptomus satanus to 60Co gamma radiation. Mesocyclops hyalinus is dominant species at site 1, near a Thermal Power Plant at Kolaghat East Midnapore where fly ash deposition is a regular phenomenon. Allodiaptomus satanus is dominant species at site 2 at Kolkata, Ballygung where anthroponotic activities are more pronounced. M. hyalinus is naturally exposed to more stressful situation than A. satanus as revealed by comparing the hydrological parameters of the two habitats. Experimental exposure to ionizing radiation resulted in differential changes in viability, morphology and antioxidant enzyme activities in the two selected species. Survival experiments showed greater tolerance of M. hyalinus compared to A. satanus up to 8Gy (absorbed dose) after which it showed drastic fall in survival. More pronounced morphological changes were observed in A. satanus as compared to that in M. hyalinus. The pattern of changes in antioxidant enzyme activity is distinctly opposite in the two radiation exposed species. While in M. hyalinus stimulation in activity of both CAT (excepting at 10Gy absorbed dose) and SOD was observed A. satanus showed decrease in activity of both the enzymes when compared to their unirradiated counterparts.