Effect of temperature, salinity and size on cadmium toxicity in an intertidal gastropod, Turbo intercostalis (Gastropoda-Turbinidae) from Visakhapatnam, east coast of India

摘要

Laboratory studies were made to determine the toxicity of cadmium in an intertidal gastropod, Turbo intercostalis in relation to temperature, salinity and size. The snails were exposed to various concentrations of cadmium at two different temperatures and salinities. The tolerance experiments were also conducted with medium and small sized snails. Mortality rates increased with increasing cadmium concentration at all the different parameters studied. At ambient temperature (29℃) and salinity (32per thousand), the LC_(50) of 6.1844 ppm was obtained for 96 hr when the medium-sized snails were exposed to different concentrations. The LC_(50) values of 0.3629 and 0.0577 ppm obtained at low (25℃) and high (33℃) temperatures respectively were found to be significantly (P < 0.05) lower than that of ambient temperature. Similarly, low LC_(50) values of 1.154 and 0.3722 ppm were observed at low (20per thousand) and high (35per thousand) salinities respectively. The small size animals showed LC_(50) value of 2.774 ppm, which is significantly lower (P < 0.05) than that of the medium sized snails. The results clearly demonstrated that the toxicity of cadmium changes with size and environmental variables in T. intercostalis.