Elevated trace element concentrations and standard metabolic rate in banded water snakes (Nerodia fasciata) exposed to coal combustion wastes

Abstract

Abstract-Trace element concentrations in banded water snakes, Nerodia fasciata, and representative prey items from a site polluted by coal combustion wastes were compared with concentrations in conspecifics from a nearby reference site. Water snakes accumulated high concentrations of trace elements, especially arsenic (As) and selenium (Se), in the polluted habitat. In addition to being exposed to contaminants in water and sediments, snakes in the polluted site are exposed to contaminants by ingesting prey items that have elevated whole-body concentrations of trace elements, including As, cadmium (Cd), and Se. Snakes from the polluted site exhibited mean standard metabolic rates (SMR) 32% higher than snakes from the reference site. As a result, snakes from the polluted site appear to have elevated allocation of energy to maintenance and theoretically should have less energy available for growth, reproduction, and storage. Our findings are consistent with physiological responses recently documented in other organisms from the polluted site. We hypothesize that long-term exposure to coal ash-derived trace elements and the resultant accumulation of some elements are responsible for observed increases in SMR.

Respiratory and Reproductive Characteristics of Eastern Mosquitofish (Gambusia holbrooki) Inhabiting a Coal Ash Settling Basin

“…The lack of effect on SMR contrasts previous work (Rowe et al 1998Hopkins et al 1999) in which other diverse organisms (bullfrogs, banded water snakes, and crayfish) collected from the ASH system exhibit SMRs (mL/g ⅐ h) approximately 23-32% higher than conspecifics from reference sites. Given that SMR is an indirect measure of an organism's maintenance costs, the elevated SMRs of other ASH organisms suggested that they incurred energetic costs, perhaps as a result of energy required to facilitate toxicant elimination or repair toxicant-induced cellular damage (Calow 1991).…”

“…The REF site is an abandoned (greater 50 years) farm pond (1.1 ha, 2.5 m maximum depth; pH and conductivity (mean Ϯ SE): 6.33 Ϯ 0.11 and 28 Ϯ 0.2 S/cm respectively), and is located approximately 4.1 km from the ash basins. At least 12 previous toxicological and life history studies have used Risher Pond as a reference site because it is located in a forested area, has not been subject to human encroachment within the watershed for greater than 50 years, and has no known history of contamination, exposure to elevated levels of any toxicant, nor any history of input of coal ash (e.g., Hopkins et al 1999;Lee et al 1992;Meffe 1991;Meffe and Snelson 1993).…”

“…A number of fish species and other organisms have been documented to be sensitive to coal ash, a byproduct of coal combustion at electricity generation plants, and wastewater runoff from coal ash settling basins (Cherry et al 1976(Cherry et al , 1984Hopkins et al 1999Hopkins et al , 2000aHopkins et al , 2000bLemly 1985;Lohner et al 2001aLohner et al , 2001bLohner et al , 2001cRowe et al 1998). Of 20 fish species inhabiting Belews Lake, North Carolina prior to selenium (Se) contamination from ash basin drain water, 16 were extirpated from the lake apparently due to reproductive failure associated with the contamination (Lemly 1985(Lemly , 1997.…”

“…Eastern mosquitofish (Gambusia holbrooki) were one of four species (including common carp, Cyprinus carpio; fathead minnows, Pimephales promelas; and black bullheads, Ictalurus melas) that remained in Belews Lake after Se-contamination and was the only species that appeared to maintain a reproductively viable population (Lemly 1985). In other systems associated with power plants, eastern mosquitofish persist in ash settling basins (Cherry et al 1976;Hopkins et al 1999) and sunfish remain in streams that receive fly ash pond runoff with seemingly few detectable negative effects (Lohner et al 2001a(Lohner et al , 2001b(Lohner et al , 2001c.…”

“…A variety of organisms (i.e. bullfrogs, Rana catesbeiana; banded water snakes, Nerodia fasciata; and crayfish, Procambarus acutus) exposed to conditions in ash basins located on the Savannah River Site (SRS), Aiken, South Carolina, exhibit increased SMRs, an indirect estimate of an organism's maintenance costs (Rowe et al 1998Hopkins et al 1999). Presumably an increase in SMR results from energetically costly processes associated with combating contaminant exposure (e.g., cellular repair mechanisms, elimination of contaminants).…”