Ecotoxicology
Anthropogenic contaminants are widespread throughout many ecosystems and represent one of the greatest threats to biodiversity world-wide. Recognition of this threat has prompted extensive investigation into the accumulation and effects of contaminants in a variety of taxa. In particular, given their reliance on aquatic ecosystems and unique life history, much of this focus has been centered on understanding effects in amphibians. However, some contaminants may biomagnify within food webs and thus investigation of the fate and effects of contaminants among various levels of trophic organization is of critical importance. In particular, investigation of the accumulation of contaminants within consumable tissues of game species is of acute importance to human health, yet few data are available for many commonly harvested species. Such research is particularly important for migratory species or those capable of long distance movements (e.g., waterfowl) where potential exposure risks to hunters may be unknown.
ACCUMULATION OF CONTAMINANTS IN GAME SPECIES
SREL Collaborators: Jim Beasley, Larry Bryan, Bobby Kennamer, Chris Leaphart, Cody Tisdale, Allie Rakowski, Ernest Borchert
We are currently sampling common game species in the southeastern U.S. to quantify concentrations of radiocesium, mercury, and a suite of other metals/metalloids in consumable animal tissues. In addition, for some species we are collecting endoparasites and other samples to assess the sub-lethal effects of contaminant exposure to wildlife. These studies are being conducted in habitats on the Savannah River Site where the distribution and extent of environmental contaminants has been extensively mapped, as well as other locations in the southeast with no known contaminant inputs. Our focus currently is on resident species such as wild pigs, raccoons, beavers, gray squirrels, wild turkeys, otters, as well as various migratory waterfowl species. From this research we will be able to determine the extent to which these species accumulate contaminants of concern within their body tissues and be able to assess whether consumption of animals inhabiting contaminated habitats poses any potential risks to human health.
RADIOCESIUM UPTAKE IN MIGRATORY WATERFOWL FROM A CONTAMINATED RESERVOIR
SREL Collaborators: Jim Beasley, Larry Bryan, Bobby Kennamer, Ricki Oldenkamp
Radiocesium is a relatively long lived radionuclide (30.2 year half-life) and radiocesium contamination from past nuclear production activities on the Savannah River Site can expose wildlife that use contaminated areas. Pond B, a reservoir on the SRS, is contaminated with radiocesium that is taken up by waterfowl and can thus be transported hundreds to thousands of miles during migration. Using a combination of historic and contemporary data, we are quantifying current levels of radiocesium taken up in consumable tissues in ring-necked ducks and American coots to elucidate changes in radiocesium burdens through time that will allow us to develop an ecological half-life for waterfowl in this ecosystem. In addition, using birds with variable, but known exposure periods, we are quantifying uptake rates of radiocesium by these species as well as changes in blood chemistry in response to exposure as a measure of sub-lethal effects of chronic, low dose radiation exposure.
ACCUMULATION RATES FOR METALS/METALLOIDS IN WATERFOWL UTILIZING COAL ASH SETTLING BASINS
SREL Collaborators: Jim Beasley, Larry Bryan, Bobby Kennamer, Ricki Oldenkamp
Coal-fired power plants are common worldwide, with more than 2,300 existing plants and an additional 1,200 planned, yet consequences of exposure to by-products of burning coal are largely unknown. Beyond increasing atmospheric carbon emissions, a considerable consequence of burning coal is concentration of metals/metalloids in coal-fly ash waste placed in settling basins and subsequent exposure to humans and wildlife. Ash basins are easily accessible to wildlife, and organisms that utilize settling basins can bioaccumulate substantial metal/metalloid burdens. Despite the global distribution of ash basins, data on their effects on wildlife are surprisingly limited. Of particular interest is accumulation of contaminants by waterfowl from exposure to coal-fly ash because ducks are capable of transporting contaminants within their tissues hundreds to thousands of miles from the source. Additionally, waterfowl are an important game and prey species and thus potentially a key pathway of contaminant exposure to humans and other wildlife. The objectives of this study, therefore, are to quantify metal/metalloid uptake in Ring-necked ducks (Aythya collaris) utilizing coal-fly ash basins over known time periods to create a predictive model of contaminant uptake rates for birds utilizing ash basins, and estimate subsequent health risks to waterfowl hunters.
ENVIRONMENTAL CONTAMINANTS AND BLOOD PARASITE LOADS IN BLACK AND TURKEY VULTURES
SREL Collaborators: Jim Beasley, Amanda Holland, Larry Bryan
Outside Collaborators: Sonia Hernandez (UGA), Michael Yabsley (UGA)
Recent links between catastrophic vulture declines and anthropogenic hazards have drawn international attention to the vulnerability of scavengers to environmental contamination. Vultures rely on carrion resources, have relatively long life spans, and are thus particularly susceptible to bioaccumulation of metals and other anthropogenic contaminants. Black (Coragyps atratus) and Turkey vultures (Cathartes aura) are widely dispersed throughout much of the United States and potentially exposed to a number of anthropogenic contaminant sources on a regular basis due to frequent foraging at hunter-killed carcasses, landfills, and other contaminated sites. By-products of hunter-kills provide an essential food source for vultures and other scavengers, but accidental ingestion of lead ammunition fragments can result in lead toxicosis and death. Additionally, landfills contain high levels of anthropogenic toxicants, including polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) which can have adverse effects on endocrine systems and reproductive abilities. Understanding levels and sources of contamination to which vultures are exposed remains an important area of research.
Comparisons of metal and metalloids contamination in sympatric black and turkey vultures are entirely lacking, and assessments of lead levels have not yet been fully examined for either species in the southeastern United States. Furthermore, no prior studies have assessed intensity of blood parasites as representative of immunodeficiency caused by contaminant exposure in black and turkey vultures. The objectives of this research are to quantify metal/metalloid burdens and elucidate the relationship between contamination levels and blood parasite loads in vulture populations in the southeastern United States. Results from this study will provide information on the extent to which avian scavengers are exposed to contaminants and the potential effects of contaminants on the health of scavenging communities in the southeastern United States.
EFFECTS OF METHYLMERCURY ACCUMULATION IN WATERFOWL DUCKLINGS EXPOSED DURING EMBRYONIC DEVELOPMENT
SREL Collaborators: Jim Beasley, Chris Leaphart
Methylmercury (MeHg) is a pervasive heavy metal toxicant that is known for its detrimental effects on wildlife in diverse ecosystems across the globe. In aquatic, terrestrial, and marine ecosystems, MeHg can bioaccumulate in wildlife via dietary exposure, and undergoes biomagnification with each increasing trophic position in food webs. For birds, some species of waterfowl, waterbirds, and raptors are at the upmost risk of MeHg accumulation given their intermediate to high trophic position and associated diet within wetland environments, as well as their species-specific sensitivity to MeHg. Birds exposed to MeHg have been shown to experience adverse health and reproductive effects, and even death. MeHg is also maternally transferred to eggs laid by contaminated females, exposing embryos during sensitive stages of development. Although studies have previously examined the teratogenic and embryotoxic effects of waterfowl exposed to MeHg in ovo, few have examined its effects on offspring post-hatch. Therefore, the objective of this study is to further investigate MeHg accumulation in waterfowl embryos exposed during embryonic development, and to assess its effects on newly hatched duckling health, behavior, condition, and survival. Not only will this research further examine the negative effects associated with anthropogenic pollution in wildlife, it will also further demonstrate how sub-optimal conditions during embryonic development can have potential life-long effects.
BIOACCUMULATION OF HEAVY METALS AND RADIONUCLIDES IN WATERFOWL UTILIZING CONTAMINATED ENVIRONMENTS
SREL Collaborators: Jim Beasley, Chris Leaphart, Larry Bryan, Bobby Kennamer
Waterfowl face numerous anthropogenic threats globally through the degradation and destruction of wetland habitats, pollution, and changing climate conditions. Although waterfowl and wetland conservation efforts have promoted wetland restoration and preservation to increase the availability of waterfowl habitat, inputs of anthropogenic pollution into aquatic habitats remain a potential threat to both waterfowl populations and human hunters who might be exposed to contaminants through consumption of game meat. Given their ability to accumulate various heavy metals and radionuclides within their tissues and organs through dietary exposure, waterfowl heavily exposed can encounter a suite of adverse health-related complications, reproductive impairment, and even death. To better understand contaminant accumulation in waterfowl utilizing contaminated aquatic systems, we sample waterfowl utilizing various wetlands and reservoirs on the U.S. Department of Energy’s Savannah River Site. Species sampled include resident birds breeding on the SRS, as well as migratory birds using the SRS as a stop-over site on their journey or as a winter feeding ground. These data are used to model contaminant uptake over time, as well as for risk assessments to examine potential impacts on waterfowl health and reproduction, as well as potential human exposure from unknowingly hunting and consuming contaminated birds.