Vol. 5, Issue 2 (2020)
Study of interrelations between seasonal estuarine water parameters and cadmium chloride toxicity to estuarine clam. Meretrix (Linnaeus)
Author(s): Sanjay Kumbhar
Abstract: In the present investigation, acute static bioassays were conducted during summer, monsoon and winter season of 2019. During each season and before bioassay test, estuarine water samples were collected and analysed to quantify the cadmium. In April it was below detectable level. In July and December, it was 0.005 and 0.001ug/ml respectivly. Significant concentration of cadmium in monsoon was due heavy impounding of cadmium enriched soil, carried through rainy freshets. These values were considered during further experimental procedures. Static bioassay yielded different LC0 and LC50 values during three different seasons. During summer, calculated and observed LC50 values were 1.7961 and 1.8 ppm respectively. The regression equation established is Y =2.8358+8.5506 log X. In monsoon, the calculated and observed LC50 values were 2.1521 and 2.0ppm respectively. The regression equation established is Y=0.5702+13.3074 log X. During winter, calculated and observed LC50 values were 2.0946 and 2,1ppm. respectively. Regression coefficient established is Y= 1.0549+12.2856 log X. In the present study, it was found that, clams become more susceptible for cadmium toxicity in summer when water temperature and salinity was more. Increased water temperature, salinity and decreased river influx caused decrease in oxygen saturation in water. In monsoon, although water was impregnated with non-significant concentration of cadmium (0.005µg/l) clams showed better resistance to cadmium because of optimum range of water parameters.