Pilot study for a sperm quality-based reproductive assessment scheme for deer

Ecological risk assessments (ERAs) for mammals at chemically contaminated terrestrial sites conventionally apply a food-chain model to draw inferences about a population's reproductive condition. Very recently though, the ERA field was advanced beyond the desktop level with the introduction of Rodent Sperm Analysis (RSA), a direct health status assessment method for the actual chemically exposed site receptor. Here, the sperm parameters of rodents (count, motility, morphology) of contaminated sites and their habitat-matched noncontaminated reference locations are comparatively reviewed for a technically supported indication of reproductive capability, ERA's toxicological endpoint of greatest concern. With the extent to which sperm parameters need to be impaired in order to compromise reproduction being known, more definitive determinations are possible than with the food-chain model approach. We sought to adapt the RSA method to the white-tailed deer (Odocoileus virginianus), recognizing that this commonly evaluated mammalian species of ERAs is one of a very few species that avails itself to regularly being removed (through hunting) from the field. We conclude that the adaptation is viable, although sperm motility and a few other measures routinely compiled in RSA applications cannot be collected. In the pilot application, the deer population we assessed, with exposures to Superfund and other sites of known contamination, was not found to have compromised reproduction. This finding is consistent with RSA's supporting theory as well as population census information. The outcomes of so-called deer sperm analysis applications for herds exposed to one or more environmental stressors, have the potential to serve as reliable indicators of reproductive status. Such outcomes also provide further weight-of-evidence that suspected contamination is not associated with adverse ecological effects.