Reproductive impairment of sea urchins upon chronic exposure to cadmium. Part I: Effects on gamete quality

Successful reproduction is a determining factor for species survival. Pollu tion may impair reproductive success of adults through effects on gamete qu ality. Reproductive impairment of the sea urchin Anthocidaris crassipina up on chronic (4 weeks) exposure to 0.01 and 0.1 mg 1(-1) Cd2+ was investigate d. Criteria used for assessing gamete quality included sperm motility, egg morphology, fertilization rate and dynamics of first cleavage. A dose-respo nse relationship was found between Cd2+ levels and changes in sperm motilit y, and percentage fertilization. Sperm motility, measured by computer-assis ted sperm analysis, indicated that percent motile sperm, velocities, and pe rcent sperm with normal trajectory were significantly affected by chronic e xposure to greater than or equal to 0.1 mg 1(-1) Cd2+. A decline in sperm m otility was also accompanied by a decrease in fertilization success of sea urchin sperm. Width/height ratio of sea urchin eggs was not affected by cad mium, but larger egg sizes were found when sea urchins were exposed to 0.1 mg 1(-1) Cd2+. Male sea urchins exposed to Cd2+ produced poorer quality spe rm, as indicated by a lower percent fertilization and lower cleavage rate, implying that male sea urchins were more sensitive than females to chronic Cd2+ exposure. Results of the present study provide an explanation of repro ductive impairment in marine invertebrates upon chronic exposure to Cd2+. ( C) 2000 Elsevier Science Ltd. All rights reserved.