Sexually dimorphic morphology of hatchling snapping turtles (Chelydra serpentina) from contaminated and reference sites in the Great Lakes and St. Lawrence River basin, North America.

Some organochlorine pesticides and industrial chemicals may alter sexually dimorphic traits through endocrine disruption. Therefore, we examined a sexually dimorphic trait, precloacal length, of hatchling snapping turtles (Chelydra serpentina) incubated from 31 clutches from a heavily contaminated site (Hamilton Harbour, ON, Canada; n = 14), a moderately contaminated site (Akwesasne Mohawk Territory; n = 3), and from a reference site (Algonquin Provincial Park, ON, Canada; n = 14). The mean sum polychlorinated biphenyls from Algonquin were low (20.33 ng/g wet wt), but were high from both Hamilton and Akwesasne (2,956.28 and 3,377.0 ng/g wet wt, respectively). Organochlorine pesticides, such as dichlorodiphenyldichloroethylene, were low from Algonquin (1.67 ng/g wet wt), moderate from Akwesasne (10.00 ng/g wet wt), and relatively high from Hamilton (135.14 ng/g wet wt). At all sites, the precloacal length of male hatchlings was larger than that of females by an equal amount at any given body size. However, the precloacal length of both males and females from Hamilton increased with body size at a slower rate than of males and females from the other two sites. Our results support an earlier study that found differences in sexually dimorphic morphology of adult snapping turtles among contaminated and uncontaminated sites. Furthermore, these alterations in secondary sexual characteristics previously observed in adults likely are initiated early in development, and may result in permanent organizational changes in morphology.