Toxicity of Hg (II) to prawns Penaeus monodon and Penaeus indicus (Crustacea: Penaeidae) from Rushikulya estuary, Bay of Bengal

摘要

Penaeid prawns belonging to size 35-55 mm TL and 55-75 mm TL were exposed to the five concentrations of Hg (II) in salinities 5, 15, and 25 per thousand. The values of LC_(50) with 95% confidence limit for 96 hours were 0.036 (0.032-0.041) and 0.042 (0.036-0.044) mg l~(-1) for large size groups of P. monodon and P. indicus respectively. The LC_(50) decreased with increase of time period. Small size groups were more sensitive to mercury at lower salinities while large size groups were more tolerant at high salinities. Penaeus monodon was more sensitive to mercury than P. indicus at each salinity. Threshold limit for P. monodon and P. indicus was 0.016 and 0.024 mg l~(-1) respectively.