Exposure of male American plaice (Hippoglossoides platessoides) to contaminated marine sediments decreases the hatching success of their progeny

There is increasing concern over the effect environmental contaminants may be having on male vertebrate reproduction, particularly persistent organics. This study sought to determine the effects of marine sediments, contaminated with organic compounds, on the reproductive performance of male American plaice (Hippoglossoides platessoides). Maturing fish were exposed to contaminated sediments, in the laboratory, for a 5-month period leading up to spawning. Sediments were obtained from three known environmentally contaminated sites, in which site 1 was the most toxic, followed by site 2, with site 3 relatively uncontaminated (i.e., control). Semen collected from all males with motile sperm were used to fertilize eggs from a single nonsediment-exposed female. Eggs fertilized with sperm from males exposed to sediments from site 1 produced 48% fewer larvae (p < 0.05), compared to the control group (i.e., site 3). Similarly, males exposed to site 2 produced 35% fewer larvae, relative to the control. There were no differences between groups with respect to sperm number, seminal sodium and potassium concentrations, and gonadosomatic index. The levels of liver cytochrome P450 1A1 (CYP1A1) mRNA, used as a biomarker for exposure to organics, were threefold higher in fish exposed to site 1 sediments, and twofold higher in fish exposed to site 2 sediments, relative to the site 3-exposed controls, at the end of the experiment. A significant negative correlation (r = -0.65, n = 16, p < 0.007) exists between male CYP1A1 levels and hatch success, with increasing CYP1A1 levels corresponding to decreased numbers of hatched larvae. These data indicate that long-term exposure of male American plaice to marine sediments contaminated with organics can result in a reduction in the number of eggs hatched, which correlates with increased levels of hepatic CYP1A1.