Humoral and Haemocytic Responses of Litopenaeus vannamei

White shrimp, Litopenaeus vannamei, subadults were exposed to four dilutions of the 96 h cadmium LC50 reported for postlarvae (PL12) of this species, and the effects were evaluated after 5, 48, and 96 h of exposure. While treatments did not affect survival and hemolymph clotting time increased with time, but not as a response to Cd exposure, the intensity of other responses was related to concentration, to time of exposure, and to their interaction. Hemocyanin decreased with time in all metal concentrations but increased in the control treatment, and an almost similar trend was observed with hemocyte numbers. As an initial response, phenoloxidase activity decreased with all metal concentrations, but it increased later to values similar or higher than the control treatment