Changes in reproductive potential of the leech Nephelopsis obscura (Erpobdellidae) as biomarkers for cadmium stress

Abstract

The effects of exposure for 4–24 days to 0, 58, 145, 290, 435, and 580 μg∙L−1 cadmium on the reproductive potential of the freshwater predatory leech Nephelopsis obscura were investigated. The numbers of ova and spermatozoa per unit biomass were significantly reduced with increasing cadmium concentration and exposure time, as were the masses of the ovisacs, testisacs, and epididymis plus cornu. It is concluded that these variables are effective biomarkers for identifying sublethal effects of direct importance to population dynamics.