No abstract

Experiments are reported on the effects of the insecticide Sevin and its hydrolytic product, 1-naphthol, on the survival, growth, and food consumption of larval and juvenile cockle clams (Clinocardium nuttalli). Clams were tested in standing sea water at a salinity of 25‰ and a temperature of 19 ± 2.0 C, and were fed cultures of the unicellular alga Monochryis lutheri. Algal cell concentrations ranged from 10,000 to 200,000 cells per ml of test solution. Toxicant concentrations ranged from 0.1 to 10.0 mg/liter.Larvae exposed to Sevin concentrations of 0.8 mg/liter were dead by day 7 of the test, and the growth of those exposed to 0.4 mg/liter was reduced by 15%. Sevin was less toxic than 1-naphthol to juvenile clams, the respective 96-hr TLm's (median tolerance limits) being 3.75 and 2.70 mg/liter. The growth of juvenile clams was reduced more by 1-naphthol than by Sevin. The food consumption of juvenile clams exposed to 1.6 mg/liter of Sevin was markedly reduced and their food conversion efficiency was impaired.Adult clams exposed to Sevin concentrated the toxicant in their tissues; maximum concentrations were reached after 12 hr of exposure. Clams exposed at 11 C concentrated more toxicant than those exposed at 20 C. Tissue concentrations of toxicant decreased sharply after the clams had been in clean sea water for 12 hr.