Survival and Histological Alterations in Juvenile Tiger Shrimps Exposed to Saponin

Survival and shell quality of juvenile tiger shrimp, Penaeus monodon, exposed to a plant derived toxicant, saponin, were investigated. The 96 h LC₅₀ was 132.07 mg l^-1 of saponin. The juvenile tiger shrimp tested against 5, 10, 15 and 20% concentrations of the 96 h LC₅₀ value of saponin for 3, 6, 9, 12, 15 and 18 days recorded shell softening ranging from 3.33 to 60% of the individuals. The percentage of shell softening in the treated shrimps was dependent on both concentration and duration of exposure. The cuticular layers of soft-shelled shrimps were thinner and often had wrinkled surfaces which usually disrupted and separated from the epidermis. In the hepatopancreas of the soft-shelled shrimps, the major alterations were the degeneration of hepatopancreatic tubules, separation of basal laminae from the tubules and reduced lumen of tubules.