Throughout the world, coal-fired power plants produce large quantities of wastes (fly-ash and bottom-ash) that are enriched in various trace elements, including As, Se, Cd, Cr, and Hg. Many aquatic and terrestrial habitats close to areas of waste production and disposal become contaminated with trace elements, potentially impacting the biota. We are conducting a series of projects intended to determine how the physiology, behavior, and morphology of organisms are modified by exposure to coal-derived trace elements. Initially, we worked with tadpoles of the bullfrog (Rana catesbeiana) which are abundant in a nearby coal ash disposal system. When raised in the polluted area, tadpoles had a high incidence of deformities of the labial teeth, and an associated inability to consume certain food types. Tadpoles from the polluted area also have much higher than normal metabolic rates, indicating that the basic energetic costs of survival are higher in the coal ash polluted area than in unpolluted sites. Swimming ability is also impaired in tadpoles in the polluted site, resulting in higher susceptibility to predation. Thus, while the pollutants in the impacted site are not acutely toxic to bullfrogs, a combination of more subtle effects appears to be substantially affecting recruitment of juveniles from the system.
In other studies, we have found that exposure to coal combustion wastes results in: 1) modified hormonal responses in adult southern toads (Bufo terrestris), 2) transfer of some trace elements to embryos in slider turtles (Trachemys scripta), 3) modified energy budgets in toads and freshwater shrimp (Palaemonetes paludosus), 4) high mortality in spring peepers (Pseudacris crucifer), and 5) high levels of accumulation of trace elements in tissues of several amphibians, reptiles, and invertebrates. Currently, studies are underway to determine the effects of coal combustion wastes on: 1) hormone cycles in eels (Anguilla rostrata) and slider turtles, 2) genetics and physiology of mosquito fish (Gambusia affinis) and snails (Campeloma decisum), 3) susceptibility of largemouth bass (Micropterus salmoides) and water snakes (Nerodia taxispilota) to parasitic infections, and 4) energetics of limb regeneration in crayfish (Procambarus acutus).
Personnel involved in the projects described above:
Justin Congdon, Roy Nagle, William Hopkins, Tom Hinton, David Scott, Sandra Raimondo, Owen Kinney, Alison Fiori, Virginia Coffman, Julie Duetsch, David Kling, and Ruth Estes.