Heavy metal contamination and antioxidant response of a freshwater bryozoan (Lophopus crystallinus Pall., Phylactolaemata).

Monthly variations of total glutathione, glutathione-S-transferases, glutathione peroxidase, glutathione reductase, glyoxalase I, glyoxalase II, and catalase were studied in Lophopus crystallinus, a freshwater bryozoan, collected from Lake Piediluco. Specimens were sampled during the vegetative period from November to April for two different cycles: cycle I from 1996 to 1997 and cycle II from 1999 to 2000. Simultaneously, analyses of heavy metal content such as lead, cadmium, chromium, nickel, copper, iron, and zinc were determined in the samples of L. crystallinus. Specimens of cycle II displayed highest chromium and iron accumulation and elevated levels of biochemical parameters. Total glutathione content, catalase, and glutathione peroxidase activities, were related with the highest metal concentrations in L. crystallinus from Lake Piediluco.