Abstract: Toxic effect of suspension and lixivium from the dredged sludge of the Yangshan channel project on megalopa of Portunus trituberculatus was evaluated, through a laboratory simulation experiment.Results show that (1) mortality of the megalopa increased gradually with concentration of the suspension and lixivium, and 96h LC₅₀ and SC of the lixivium to megalopa of Portunus trituberculatus was  1294.66 ml·L^-1 and 129.466ml·L^-1, respectively, and of the suspension, 996.17ml·L^-1 and 99.617ml·L^-1, respectively; (2) molting rate of the megalopa decreased with increasing concentration of the suspension and lixivium; it was slightly higher in the group of lixivium treatments than in the group of suspension treatments group when they were the same in volume concentration; the suspension inhibited molting of megalopa, while the lixivium inhibited hardening of new shell; (3) After 24 hours of exposure to the suspension and lixivium, the expression of HSP70 in the muscle of megalopa increased rapidly, after 72 hours, it peaked in all the treatments, and after 96 hours, it decreased to a varying extent in all the treatments and the most significantly in the treatment the highest in concentration, while in the control it kept on rising.

Key words: suspension, lixivium, Portunus trituberculatus, molting rate, HSP70