Chernobyl & Fukushima Wildlife Research

It is widely recognized that acute exposure to high levels of radiation causes morbidity and mortality in wildlife. However, there are significant data gaps regarding the effects of chronic low-dose exposure to wildlife and thus no consensus on the potential environmental impacts of nuclear energy and/or accidents. Of the sites impacted by radiation contamination, the human exclusion zones surrounding the Chernobyl and Fukushima-Daiichi nuclear power plant accidents provide a model system for examining impacts of radiation on wildlife. Studies in these landscapes have primarily focused on individual, and occasionally population-level effects to invertebrates, birds, and in some cases small mammals. Surprisingly, few studies have been conducted on wolves, wild boar, or other large mammals, species that exhibit some of the highest levels of radionuclide burdens within their tissues. Along with a group of international collaborators, our prior research in Chernobyl has shown that populations of large mammals have increased since the evacuation of humans from the exclusion zone, despite the presence of high levels of radiation. Our current research seeks to build upon these studies to further our understanding of the ecology, population dynamics, and health of wildlife inhabiting contaminated areas in Chernobyl and Fukushima.

Chernobyl Research

Spatial ecology and sub-lethal effects of chronic radiation exposure in gray wolves and raccoon dogs in Chernobyl

We are working with researchers from the Belarus National Academy of Sciences and biologists at the Polyese State Radioecological Reserve to study individual and population level effects of radiation on gray wolves, raccoon dogs, and other large mammals in the Chernobyl Exclusion Zone (CEZ). In collaboration with the French Institute of Radioprotection and Nuclear Safety, we have developed a new scientific tool that collects an animal’s location and short-term integrated dose and attached these units to gray wolves within the CEZ. These collars have allowed us to quantify the spatial and temporal variation in radiation levels that wild, free-ranging animals experience in areas surrounding nuclear accidents. In addition, using these data and data collected from collars placed on other species in the CEZ, we are currently studying the spatial ecology of carnivores in the CEZ. Using samples collected from captured individuals we also are conducting various health assessments to quantify the sub-lethal effects of chronic radiation exposure in apex predators living in habitats surrounding Chernobyl.

Abundance and distribution of large mammals within the Chernobyl Exclusion Zone

Since the evacuation of humans from the landscape surrounding Chernobyl in 1986, wildlife populations have persisted throughout the exclusion zone, including some of the most severely contaminated areas. Yet, information on the distribution and abundance of large mammals in the Chernobyl Exclusion Zone (CEZ), particularly in relation to the distribution of radiation contamination, is limited. Such information is greatly needed to develop appropriate safeguards for wildlife within the CEZ and other areas contaminated with radiation. Our lab has been conducting research within the CEZ over the last several years to investigate the impacts of chronic radiation exposure on the occurrence, distribution, and abundance of several wildlife species within the CEZ. Specifically, we are using a combination of scent stations, scat surveys, and unbaited motion activated cameras to survey populations of gray wolves, raccoon dogs, Eurasian lynx, European brown bear, European badger, pine marten, red fox, wild boar, Przwalski’s horses, and other mammalian species within the CEZ. In addition, we have used remote cameras to elucidate the composition of vertebrate scavenger communities within the CEZ. Data collected from the surveys has revealed that many species of large mammals are now abundant and widely distributed throughout the CEZ, including species absent or highly limited in number prior to the accident. Thus, the CEZ appears to be serving as a de facto nature reserve for wildlife despite the high levels of radiation that persist throughout the landscape.

Evaluating the diet composition of gray wolves in the Chernobyl Exclusion Zone

After the Chernobyl nuclear power plant accident in 1986, many wildlife species experienced population increases within the Chernobyl Exclusion Zone (CEZ) following the reduction in anthropogenic activity, including wolves. However, the ecology and behavior of wolves that have repopulated the CEZ are poorly understood, including the extent to which individuals within the CEZ interact with the surrounding human-dominated landscape. Using DNA metaboarcoding analysis of wolf fecal samples, our objectives in this study are to (1) quantify the composition of species wolves use as food resources within the CEZ, and (2) whether wolves within peripheral areas of the CEZ consume livestock from the surrounding area. This research ultimately will provide the most comprehensive assessment to date regarding the dietary habits of large predators within the CEZ. These results will aid in the protection and management of wolves and provide insight into the ecology and behavior of wildlife in the CEZ.

Fukushima Research

Effects of human habitation on the abundance and spatial ecology of wildlife in Fukushima, Japan

Following the Chernobyl nuclear accident, many large mammal species increased in abundance, likely due to the removal of humans from the landscape. However, many questions remain regarding how quickly populations increased and the extent to which chronic radiation exposure may be impacting wildlife in areas impacted by nuclear accidents. We are conducting numerous studies within the Fukushima Exclusion Zone to better understand the extent to which radiation exposure, and the evacuation of humans from the landscape, are influencing the community composition, population dynamics, movements, and health of wildlife. Through the use of remote cameras and GPS collars, these studies aim to determine the distribution and relative abundance of wildlife in and around the Fukushima exclusion zone. These data will provide unique insights into the response of wildlife populations to the evacuation of humans from the landscape, data that will serve as baseline assessments for future monitoring efforts, as well as important data from which radiation-effects studies can be based. We also are attaching GPS collars to civets, raccoons, wild boar, and other wildlife species to determine the resource selection, activity, and movement patterns of these species within the human evacuation zone. For some species, like wild boar, we are also attaching GPS-dosimetry collars and using radiological measurements recorded by these collars along with varying resolutions of environmental contamination data and animal space use metrics. These results will be used to develop guidance on conducting ecological risk assessments and dose-effects studies.

Effects of anthropogenic activity on vertebrate scavenging communities in Fukushima, Japan

The Fukushima Daiichi Nuclear Power Plant Accident in 2011 resulted in the evacuation of hundreds of thousands of people from affected areas in Fukushima, Japan. The drastic decrease in human activity on the landscape may have repercussions for ecosystem functions, which has become an active area of scientific research. Previous studies by our lab in both Chernobyl and Fukushima have revealed that many native scavengers like wild boar have increased in abundance in abandoned areas where there is limited human activity. Such differences in wildlife community composition among areas of varying human presence could have important implications for scavenging efficiency and energy distribution within the food web. By studying how anthropogenic activities influence food web dynamics, we can understand the extent to which human presence results in cascading effects on ecosystem services like carcass removal and nutrient cycling. In collaboration with Fukushima University, we are conducting studies using remote game cameras placed at carcasses in different habitats to record scavenging activity inside the Exclusion Zone as well as the surrounding landscape to 1) quantify the effects of carcass size and habitat on the detection rates and composition of scavenger communities, and 2) determine if scavenger community composition and scavenging activity patterns vary between areas of high and low human activity, and how this impacts the efficiency of carcass removal.

Radiocesium accumulation and spatial ecology of snakes in Fukushima, Japan

Snakes are an important part of the food web in many ecosystems, but are vulnerable to bioaccumulation of contaminants due to their small home ranges and relatively long lives. Although snakes in the Fukushima Exclusion Zone (FEZ) are likely chronically exposed to elevated radiation levels due to their trophic position and close contact with contaminated soil, they remain understudied. This study is the first to quantify radionuclide burdens in snakes inhabiting the FEZ and surrounding areas and will reveal the efficacy of using OSL dosimeters with GPS transmitters to track radiation accumulation and resource selection patterns in snakes.

Reproductive health of wild boar in Fukushima, Japan

Extensive anthropogenic inputs of radionuclides have occurred through nuclear weapons testing, maintenance of nuclear power plants, and nuclear accidents such as those in Chernobyl (1986) and Fukushima Daiichi (2011). The ecological impacts of these anthropogenic inputs are an important area of research, with considerable uncertainty remaining regarding dose-effects thresholds for many health endpoints. Reproduction is thought to be the among the most sensitive ecological endpoints to radiation exposure, with potential consequences to the abundance and fecundity of exposed wildlife populations. Indeed, biomedical studies on humans have shown that exposure to radiation may affect reproduction of both sexes. Exposure to radiation may also increase the rate of deleterious mutations across subsequent generations and may increase disease susceptibility, thus decreasing survival and reproductive success of individuals and across populations. However, chronic exposure to radiation is not well understood and no studies to date have assessed the reproductive health of large, wild mammals in areas impacted by nuclear accidents. To address this research gap, we are collecting reproductive tissue samples from male and female wild boar within the Fukushima Exclusion Zone and surrounding area to assess the reproductive health of wild boar chronically exposed to radiation. Results from this research will yield critical new insights into the reproductive health of wildlife inhabiting landscapes impacted by radiological contamination.

Alteration of the cesium-137 soil profile by wild boar rooting after the Fukushima Daiichi Nuclear Power Plant accident

Large amounts of Cesium-137 (137Cs) were released into the environment from the 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in Japan. Initially, contaminants from the accident were deposited on the surface soil layers in terrestrial ecosystems, but over time vertical migration of 137Cs has occurred, with most 137Cs now distributed a few centimeters below the soil surface. Wild boar rooting likely alters the distribution of contaminants in soil profiles by increasing erosion and bioavailability to plants and other biota. Such impacts may be particularly pronounced in areas contaminated from the FDNPP accident, given the increase in abundance of wild boar in these areas. Our objective for this study was to determine whether rooting by wild boar alters the distribution of 137Cs contamination within soil profiles through collection of soil cores from control sites and both recent and old rooting sites within the difficult-to-return zone surrounding the FDNPP. Our results from this study have revealed that soil disturbance from wild boar rooting can directly influence the distribution of contaminants within soil profiles, but that the extent to which deep layers of soil are affected depends on the unique characteristics (i.e., depth of rooting) of each rooting disturbance.

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