No abstract

Persistent contaminants are ubiquitous in our water and soil, and thus chronic exposure to environmentally relevant levels of these contaminants may pose a risk to humans and wildlife. Two species of small mammals (deer mouse, Peromyscus maniculatus and cotton rat, Sigmodon hispidus) were collected from historically dichlorodiphenyltrichloroethane (DDT)-contaminated and reference areas at the Redstone Arsenal (Huntsville, AL, USA), a US Environmental Protection Agency (USEPA)-designated Superfund site. Soil samples taken concurrently with mammal collection from the DDT abatement site exhibited DDT and dichlorodiphenyldichloroethylene (DDE) levels >1 ppm (USEPA total threshold limit concentration for DDT and DDE <1 ppm), whereas soil samples from the reference area had undetectable levels. Liver samples from individuals of both species collected in the contaminated areas also had significantly elevated DDT/DDE levels, with P. maniculatus averaging an approximately 20× greater load than that documented for S. hispidus. Both rodent species collected from the contaminated site had significantly lower total leukocyte counts and total differential blood cell counts (p = 0.01 and p = 0.04, respectively) than those collected from the nearby (~7000-m) reference site. Cellular stress indices also trended higher in both species, suggesting a potential for chronic exposure to DDT to act as a mediator of oxidative damage. The present study provides support to the idea that environmental exposure to low levels of contaminants can cause physiological consequences that may influence immune responsiveness and initiate cellular stress in resident mammals.

Fingerling Red Drum Sciaenops ocellatus were held in water recirculating systems for 4–5 weeks under selected combinations of temperature and salinity: 30°C and 35‰ (reference environment), 34°C and 45‰, or 34°C and 55‰. At the end of the culture period, condition factor, hematocrit, plasma osmolality, plasma lactate concentration, plasma glucose concentration, and liver glycogen content were determined. Responses of fish in the warm, hypersaline treatments did not differ significantly from fish in the reference treatment. Based on the results of this study, juvenile Red Drum can tolerate warm, hypersaline conditions for several weeks with no apparent detrimental effects if slowly acclimated to environmental temperature and salinity as long as food is not limiting and other water quality characteristics are acceptable.