Histological changes and survival of Litopenaeus vannamei juveniles with different copper concentrations

Survival of juvenile Litopenaeus vannamei exposed to five Cu concentrations ranging from 10 to 0.003% the 96 h median lethal concentration, which were supposed to be safe in the long term, was 0% after 1, 5 and 6 weeks for Cu concentrations of 3.512, 1.756 and 0.877 mg L− 1 (10, 5 and 2.5% the 96 h LC50). With these three concentrations there were severe time- and dose-dependent structural damages, such as necrosis, loss of regular structure and infiltration of hemocytes in the gill tissues, as well as atrophy, necrosis and irregular tubular structure in the hepatopancreas. After 9 weeks of exposure, only minor histological changes were observed with the two lower concentrations.