NEW AND ONGOING PROJECTS
U.S. SO GLOBEC Synthesis and Modeling: Understanding Interactions Between Climate Warming, Gyre Dynamics and Western Antarctic Peninsula Ecosystem Response
Investigators: Christine A. Ribic, USGS, University of Wisconsin-Madison
Funding: National Science Foundation, Polar Programs
Expected Completion: May 2009
We will investigate the causal mechanisms by which recruitment in Adelie penguin (Pygoscelis adeliae) populations is regulated by variability in the western Antarctic Peninsula (WAP) marine ecosystem, with particular emphasis on the effect of changes in sea ice. Our approach combines data collection, extensive data analyses, and the development of a bioenergetics model of Adelie penguin chick growth as a framework for investigating the factors that determine chick fledging weight, which is linked to recruitment success. Through this synthesis effort, we will compare and contrast Adelie penguin populations at 2 geographic locations, Palmer Station, Anvers Island (PAL), and Avian Island, Marguerite Bay (AVI), where respective Adelie penguin breeding populations have exhibited opposite trends. We will investigate the causal mechanisms responsible for these opposing population trends by focusing on parental food delivery to the chick, which is affected by changes in prey abundance and availability that arise due to environmental variability. The extant data available to this project span 30 years (1974-present) and 4 major programs (including SO GLOBEC and Palmer LTER) with overlapping regions of operation focused largely on Palmer Station and the WAP sector south of Anvers Island to Marguerite Bay. Statistical analyses of these data will be done within a framework of a priori models developed around four themes: demography, breeding biology, breeding chronology, and foraging ecology. The data analysis will also help inform the penguin chick growth model. The existing Adelie penguin chick growth model will be implemented using data from PAL and AVI, and interfaced with circulation-sea ice, primary production, and krill growth models that will be developed as part of other SO GLOBEC synthesis and integration activities. We will also develop scenarios such as prey switching that investigate the differences and consequences to chick growth based on AVI (silverfish and krill) and PAL (krill-dominated) diets. A second component of the field program will deploy VHF transmitters on adult AVI Adelies feeding chicks to obtain data on foraging trip durations to compare with equivalent data obtained annually at PAL. Integrating these efforts will help us address our hypotheses as well as place our results into the broader SO GLOBEC research themes
Investigators: Christine A. Ribic, USGS, University of Wisconsin-Madison
Funding: Wisconsin Department of Natural Resources
Expected Completion: June 30, 2009
This project is involved in conducting surveys of breeding grassland/farmland birds, pheasants, roadside habitat surveys and vegetation sampling for a research project evaluating the effects of landscape-scale habitat management on pheasants, waterfowl, and nongame grasslands birds in the glacial habitat restoration area in east-central Wisconsin.
Reconstructing long-term dynamics of Tropical Montane Cloud Forests
Investigator: Sara C. Hotchkiss, Department of Botany
Funding: U.S. Geological Survey
Expected Completion: June 30, 2009
Hawaiian tropical cloud forests, with high levels of endemic species, are considered extremely vulnerable to shifts in global weather patterns. Relatively small shifts in atmospheric circulation patterns are likely to trigger local changes in rainfall, cloud cover and humidity, which provides additional stresses on island biota that are already vulnerable to disturbance-related invasion of non-native species. The position of the North Pacific subtropical anticyclone and the altitude of the trade wind inversion (TWI) are fundamental drivers of local climate in Hawaii. Two scenarios are considered possible for the response of the TWI to global climate change. Climate models and recent trends in climate data support a TWI that is effectively lower in elevation, particularly due to increased frequency of El Nino events. However, paleoecological evidence suggests the opposite - TWI may move up in elevation in response to an increase in temperature. A paleorecord from a high-elevation bog on Haleakalā shows that from 5.8 to 2.2 kyr BP (a period of relatively high global temperatures) the forest limit had increased in elevation, perhaps due to a higher TWI. Other paleorecords from Hawaii provide similar results. A lower or higher TWI would have the most pronounced changes at high elevation. Thus either outcome would likely have strong effects on the vegetation at high elevation, particularly on the species composition of the Kalapawili grassland, the position of treeline, and the elevation of the montane cloud forest zone.
The goals of this project are: (1) To understand current climatic and topographic controls on high-elevation ecosystems on Haleakalā, (2) To develop a method to detect future changes in treeline and high-elevation ecosystems in response to global climate change, and (3) To determine past rates and trajectories of ecosystem responses to climate changes throughout the Holocene. This research will help us understand the sensitivity of high-elevation ecosystems and predict high-elevation response to future climate change.
U.S. SO GLOBEC Synthesis and Modeling: Mobile Top Predators Provide Large-Scale Ecological Context to the GLOBEC Area Food Web
Investigators: Christine A. Ribic, USGS, University of Wisconsin-Madison
Funding: National Science Foundation, Polar Programs
Expected Completion: September 2008
Major frontal features in the Southern Ocean have been shown in mesoscale and regional studies to affect biological processes. These features — the Southern Boundary of the Antarctic Circumpolar Current, the Antarctic Slope Front, and the marginal ice zone (MIZ) - all coincide closely in the SO GLOBEC study area. We will integrate and synthesize the distribution and occurrence patterns of highly mobile marine birds and cetaceans, gathered from 60 cruises in more than 18 multidisciplinary efforts since the late 1970s, to provide a valuable near-circumpolar context in which to test hypotheses on the ecological importance of the these features. The combined data set will span two-thirds of the Antarctic circumference, from the continent to the Polar Front. Analyses will thus provide a large-scale inter-regional comparison with the mesoscale synthesis and modeling from the specific SO GLOBEC field studies.
We will focus on marine birds and cetaceans because they are highly mobile predators and concentrate where prey is abundant and foraging efficient. Our study will address four topic areas : 1) synthesis of data sets on the abundance and distribution of target species; 2) modeling to investigate physical, biological, and coupled physical-biological processes; 3) comparative regional studies that emphasize inter-regional comparisons and coupling of target species populations; and 4) integrative analysis of the U.S. GLOBEC Programs. Upon merging the data sets, we will determine an appropriate scale of analysis, and use a set of a priori models to define the important environmental variables impacting the top predators. The modeling approach will be two-fold. First, to achieve the density estimation portion of the project, we will use generalized additive mixed models (GAMMs) to explore the importance of the environmental variables to predator density or biomass. Generalized additive mixed models will be used because they can fit a wide variety of nonlinear relationships while taking account of complex error structures. Secondly, we will use the information-theoretic approach to understand variable importance via variable weights and model averaging. We will also address autocorrelation among transect segments, and will use GAMMs to estimate population sizes stratified by feature (e.g., water mass) and region
Chronic Wasting Disease - Evaluation of Disease Patterns and Management Actions
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: Wisconsin Department of Natural Resources
Expected Completion: June 30, 2007
Chronic wasting disease (CWD) was discovered in Wisconsin white-tailed deer harvested from Deer Management Unit 70A in fall 2001. Actions taken by the Wisconsin Department of Natural Resources (WDNR) include testing to determine the geographic distribution of CWD, depopulation of deer in the area known to be infected, reduction of deer populations in areas surrounding the infected area to prevent spread of CWD, banning baiting and feeding to reduce CWD transmission and conducting research to increase understanding of CWD. In 2002, CWD was also discovered in southeastern Wisconsin and northern Illinois. This second disease area is separate from the first disease area in south-central Wisconsin, and the proximity of infected animals indicates this outbreak spans the Wisconsin-Illinois boarder.
The goals of this project are to provide technical information, scientific guidance, and related assistance to WDNR managers, University researchers, and other cooperators and agencies managing CWD in Wisconsin; provide analytical evaluation of management activities to control CWD including spatial and demographic analysis of disease patterns, temporal changes in disease prevalence, monitoring of changes in response to management programs, and assessment of surveillance programs; and provide scientific guidance and technical advice on the development and implementation of disease monitoring and surveillance programs focused on disease control efforts.
Factors Affecting CWD Transmission-A Comparison of CWD Epizootics in Wisconsin and Illinois
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: December 31, 2009
The broad objectives of this research are to identify landscape and biological factors associated with the patterns of CWD infection in white-tailed deer across southern Wisconsin and northern Illinois. An important aspect of this study is to compare differences in disease transmission between the relatively continuous deer habitat of south-central Wisconsin and the fragmented habitat of south-eastern Wisconsin/northern Illinois.
Specific project objectives include:
1) Evaluate existing spatial patterns on deer populations, habitat characteristics, and disease prevalence data to identify potential study sites, determine aerial survey methods required to estimate deer density, and compile data on deer harvest and removal for study sites. 2) Assemble comprehensive GIS data layers that include land cover/land use, topography, soil types, deer habitat, and features such as waterways, highways, and railroad right-of-ways. 3) Develop maps which relate the deer density, GIS, and the CWD prevalence data for study sites and evaluate spatial-temporal age-prevalence relationships to determine factors affecting disease transmission rates, with emphasis on density vs. frequency dependent transmission and difference between continuous and fragmented deer habitats. 4) Based on the results in Objective 3, develop predictive models to develop and evaluate adaptive approaches for CWD management or control.
The Effects of Woody Removal on a Grassland Bird Community in Southwestern Wisconsin
Investigator: Christine A. Ribic, USGS, University of Wisconsin-Madison
Funding: U.S. Fish and Wildlife Service, Wisconsin DNR
Expected Completion: December 30, 2008
Grassland birds have undergone population declines in the last third of this century that are steeper and more consistent than those of any other group of birds in North America. Major causes of these declines include habitat loss, alteration, fragmentation, and simplification. Concern over the status of these birds has elevated their conservation priority. Current research indicates that landscape-scale factors may influence grassland bird abundance and productivity in Wisconsin as much or more strongly than do factors at the field-scale. Variables such as amount and juxtaposition of woody cover, topography, amount of adjacent suitable grassland bird habitat, and the extent of contiguous open grassland vs. row crops appear to be particularly important (Ribic and Sample 2001).
Current restoration and management practices for grassland bird habitat include removal of woody features - especially linear features such as wooded fence lines - within and around grassy patches. The assumption is that enlarging grassy habitat patches by removing linear woody vegetation features will reduce the negative edge effects of habitat fragmentation, and thus have a positive effect on grassland bird populations. This positive effect is due to an assumed reduction in predation on nests by predators dependent on woody habitats, such as raccoons. Predation is the leading cause of nest failure in grassland birds; and raccoons are the dominant nest predator in southern Wisconsin grasslands.
However, recent work in southwestern Wisconsin has determined that, besides raccoons, thirteen-lined ground squirrels and other predators that prefer the interior of open grasslands to woody edges can be as important as raccoons as predators of grassland bird nests (Renfrew and Ribic 2003, Guzy, Anderson, and Ribic, unpublished data). Therefore, it is an open question as to whether enlarging grassland patches by removing woody features will benefit grassland birds, or rather does the enlargement also benefit within-grassland predators to the extent that there will be no net effect to the birds.
This project addresses an identified need for applied research on non-game bird population responses to habitat management and restoration.
The objectives of the project are to determine the impact of removing linear woody features on the density and productivity of grassland birds. Activity of predators will be determined inside and outside the grassy fields and predators of grassland bird nests will be documented.
Our predictions are as follows:
(1) grassland bird abundance and nest density will increase in fields following tree row removal; these fields will be more attractive to birds and they will pack into these larger habitats, (2) grassland bird productivity will increase on sites where woody features were removed compared to control sites where woody features were not removed, (3) after removal of woody features, the grassland-bird nest predator community will shift to more species that live within the grassland, and (4) woody-edge predator activity within woody habitat along the field edges around all the grassy sites will not change but woody-edge predator activity within the sites where woody features were removed will be reduced compared to sites where woody features were not removed. Since the reduction in woody features is a local patch-level treatment, we do not anticipate an overall landscape reduction in raccoon activity.
Modeling the Effects of Climate and Mosquitoes on Hawaiian Damselflies Dynamics
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: December 30, 2008
The goal of this research is an integration of the ecological processes of Hawaiian damselflies (demography of damselflies and mosquitoes and the functional interaction between them) with the relevant climate parameters that affect system processes (water temperature, ambient temperature, elevational gradients, pool dynamics, precipitation and running water patterns). Integration will be achieved through a modeling framework that would explicitly address the ecological process at various levels: 1) Effects of water and environmental temperature on the development rate, survival and fecundity of both species, 2) Effects of intraspecific density on adult fecundity, and larval survival and growth for both species, 3) Shape of the functional response curve of mosquito density on damselfly predation rate, 4) Effects of temperature on damselfly attack rate and success, 5) Temporal and spatial dynamics of water pools and running water as a result of climate and weather factors, and 6) Effects of water pool dynamics (desiccation or overflow) on mosquito and damselfly survival.
We will use a combination of field data and integrated laboratory experiments to measure these effects and calibrate model parameters. This information would then be used to develop a model to simulate the dynamics of mosquitoes and damselflies and predict responses under different annual climatic regimes and scenarios of global climate change. The effects of climate change on the demography and interactions of these species are likely non-linear in nature; a detailed understanding of the mechanisms and integration into models are needed to understand and evaluate these complex dynamics and to forecast these effects under various climate regimes.
Some of the modeling work on mosquitoes is currently underway in a related NSF-funded Biocomplexity project started in 2000. We have already developed a temperature and rainfall dependent model that makes specific predictions for mosquito dynamics along an elevational (temperature) gradient. The model also uses daily and accumulated precipitation to simulate the effects of drought on mosquito survival through a logistic function. This base model would serve as a template to develop a specific damselfly-mosquito model for this project. This effort requires extending the model to include riparian habitats, integrating damselfly dynamics and predation, developing a detailed calibration of climate effects on the demography of these species and understanding the role of climate in the system.
Immunization of Prairie Dogs and Other Wild Rodents against Sylvantic Plague
Investigator: Jorge Osorio, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: August 30, 2008
Plague, caused by the bacterium Yersinia pestis, is a disease of wild rodents that can afflict humans as well as other mammals (Perry and Fetherston 1997; Koornhof et al. 1999) and is well-known as the disease that has devastated human and animal populations throughout history. In the past century, plague caused severe epidemics in many parts of the world, resulting in human deaths and severe economic losses (Titball and Leary 1998). Human cases of plague in the U.S., while not numerous, are largely due to contact with infected rodents (Gage et al. 1992). Ground dwelling rodents, like prairie dogs in the western U.S., are particularly susceptible to plague, with > 90% mortality in afflicted colonies (Barnes 1982, 1993). Many animals use prairie dogs as food resources, including badgers, canine predators, hawks, and owls, (Miller et al. 1994), but the species most dependent on prairie dogs is the endangered black-footed ferret (Mustela nigripes; Sheets et al. 1971). Prairie dogs are considered a keystone species, serving a critical role in maintaining the biotic diversity and integrity of the western grasslands that stretch from southern Canada to Northern Mexico (Miller et al. 1994). The black-tailed prairie dog (once the most abundant mammal in North America) has declined to less than 2% of its former population and has been identified as a candidate for federal listing as a threatened species by the US Fish and Wildlife Service (Graber et al. 1998; USDI FWS 2000). Sylvatic plague was specifically identified as the most serious threat to the continued existence of this species over significant areas of its range. The disease has extirpated prairie dogs in some areas of North America (Fitzgerald 1993; Lechleitner et al. 1962) and often causes local extinctions and population reductions followed by partial recovery (Cully et al. 1997; Roach et al. 2001).
Plague in prairie dog towns significantly impacts black-footed ferret survival by destroying their primary prey base. In addition, the black-footed ferret is also highly susceptible to plague (Williams et al. 1994) and may suffer high mortality rates upon infection, even though other predators and closely related species, such as the domestic ferret, appear to be resistant to the disease. Plague in prairie dogs is a major impediment to the ongoing ferret recovery programs of the Bureau of Land Management, Fish and Wildlife Service, National Park Service, and numerous state agencies (Barnes 1993). An effective means of protecting prairie dogs and other wild and peridomestic rodents from plague is critically needed to 1) reduce the incidence and potential of zoonotic transmission of the disease to humans, 2) to reduce the population decline of threatened rodent species, and 3) to enhance the recovery potential of black-footed ferrets. Recent advances in biotechnology have permitted the development of safe and effective vaccines that can be used for controlling and preventing diseases in wildlife. A good example is the recombinant vaccinia-rabies glycoprotein vaccine, which has been used successfully to immunize free-ranging red fox (Vulpes vulpes) in Europe and raccoons (Procyon lotor) in southeastern U.S. using oral baits (Rupprecht et al. 2001). With an effective vaccine that can be delivered orally and an appropriate baiting system, similar technology could protect free-ranging rodents against plague. We recently evaluated raccoon poxvirus (RCN) as a vaccine delivery system for the Fraction 1 (F1) capsular antigen of Y. pestis, using mice (Osorio et al. 2003) and prairie dogs (Mencher et al. 2004) as our initial animal models. Vaccinated mice were protected from lethal plague challenge with up to 8 x 107 LD50s of Y. pestis (Osorio et al. 2003). In a subsequent experiment, vaccine was presented to prairie dogs in the form of oral bait that was voluntarily consumed (Mencher et al. 2004). The majority of vaccinated animals (56%) survived challenge with 130,000 bacteria, a severe, but realistic dose of Y. pestis that animals might receive via numerous flea bites in a natural outbreak of plague. The goal of this research is to improve the efficacy of our vaccine and boost the mucosal response.
Genetic Relatedness of Free-Ranging White-tailed Deer Related to Transmission of Chronic Wasting Disease in Wisconsin
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison,
Funding: Wisconsin Department of Natural Resources
Expected Completion: June 30, 2007
CWD was first detected in Wisconsin in three deer harvested during the 2001 fall hunting season. The source of CWD infections in Wisconsin is unknown and will likely remain unknown. However, we suspect that CWD has been present in the Wisconsin deer herd for at least 10 years. Very little is known about the routes of CWD transmission between free-ranging animals, the rates of infection, or how disease spreads within a local population. Routes of direct transmission of CWD among white-tailed deer will likely be related to the degree of social and behavioral interactions that occur in free-ranging animals. The intensity of these interactions varies depending on age/sex relationships and genetic relationships among deer. Due to social structure, genetically related adult female white-tailed deer are not randomly distributed across the landscape. Purdue et al. (2000) found that populations of white-tailed deer separated by >25 km shared very few maternally inherited mitochondrial DNA markers and had different frequencies of biparentally inherited DNA markers. Based on alleles and genotypes of a single DNA locus Scribner et al. (1997) found that white-tailed deer in an 800 km2 area of Georgia formed genetic clusters. Matthews and Porter (1993) correlated genetic clusters with matrilineal social groups that were defined by radiotelemetry data.
The general objectives of this study are to characterize the spatial genetic structuring and degree of genetic relatedness among free-ranging white-tailed deer in the CWD affected area in south-central Wisconsin. Relatedness of deer will be used to evaluate prevalence of CWD, transmission dynamics within and among related deer, genes flow related to landscape feature, or genetic resistance of deer to CWD. This research project will provide supplementary genetic information to assist the evaluation of previously funded research studies.
Serological Survey of WNV Exposure in Mammalian Scavengers in the CWD Eradication Zone
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: Wisconsin Department of Health and Family Services
Expected Completion: January 31, 2007
Although West Nile Virus (WNV) is known to infect over 58 species of mosquitoes and 284 avian species, with few exceptions little is known about its role in the cause and transmission of disease in mammalian species. Besides humans and horses, incidental cases of WNV exposure based on serological evidence have been reported in a handful of mammals such as bats, rabbits, and in sensational species such as bears, wolves, reindeer and even Barbary Macaques. In certain mammals, for example squirrels, mortality due to WNV has also been reported. For most of these species, the role of infection in the transmission of WNV is largely unknown. The objective of this research is to gain a better understanding of the incidence of WNV infection in native meso-predators during the next two years. By extending our analysis of trapped animals collected for a companion study on Chronic Wasting Disease for two more seasons, we can determine whether the elevated incidence in 2003-2004 was a result of short-term environmental conditions or an indication of a long-term transmission mechanism. In addition, we can also estimate annual changes in WNV exposure and correlate these results with transmission information from mosquito collections and human cases. Our project will continue to rely on serum samples collected at necropsy on Nobuto strips and the presence and titer of neutralizing antibodies for WNV will be performed by PRNT. Our goal is to sample around 100 animals each year from each of the following species: opossum, raccoon, and coyote, and to perform incidental testing of red fox, skunk, and feral cats as available.
Use of Genetic Markers to Investigate the Route of CWD Transmission in Free-Ranging White-Tailed Deer
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: April 30, 2008
Routes of direct transmission of CWD among white-tailed deer will likely be related to the degree of social and behavioral interactions that occur in free-ranging animals. The intensity of these interactions varies depending on age/sex relationships and genetic relationships among deer. A companion study has been initiated to evaluate transmission of CWD between does and their fawns, and among genetically related groups of does that maintain social separation from other groups. However, the importance of direct transmission between male and female deer, primarily occurring during the breeding season, has not been evaluated. In previous studies bucks and does had similar prevalence rates of CWD, indicating that transmission of disease is not exclusively male or female regulated. Recent studies in Colorado and preliminary evaluation of CWD prevalence in Wisconsin’s Eradication Zone indicate that males may have much higher prevalence rates of CWD than females, suggesting differential aspects of disease transmission and that bucks might serve as collectors of CWD infection. The objectives of this project are: 1) to use genetic markers to identify paternity and maternity among sets of fawns, bucks, and does removed from the eradication zone during 2002-03 and 2003-04; 2) to determine whether CWD infection is related to interactions among males and females during breeding; 3) to determine the probability of CWD transmission between adult male and female white-tailed deer during the breeding period.
Risk of CWD Transmission Associated with Supplemental Feeding and Baiting of Free-Ranging White-Tailed Deer
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: April 30, 2008
Prior to emergency restrictions implemented to prevent the spread of CWD in 2002-2003, supplemental feeding of wild deer was widely practiced by Wisconsin residents. Supplemental feeding concentrates deer and habituates to them to feeding sites to facilitate viewing and hunting (e.g., baiting). With CWD present, concentration and habituation likely expose deer to increased risk of CWD transmission because of the greater potential for contamination of feeding sites by infectious saliva, feces, or urine and because of enhanced contact among deer. Research in Michigan demonstrated the importance of these mechanisms and the types of supplemental feeding used in the maintenance of a bovine tuberculosis epizootic - a disease whose transmission mode may be similar. Notably, bovine tuberculosis also threatens Wisconsins deer herd through periodic outbreaks among captive ungulates. Supplemental feeding practices may include natural browse conditions (control), unrestricted feeding, and amount restrictions (e.g., 2 gallons/per day) suggested as compromise positions short of a total ban on supplemental feeding. The objectives of this project are: 1) to quantify the relative risks associated with supplemental feeding by comparing contact rates, deer use of feeding sites, and fecal contamination of free-ranging deer under different supplemental feeding practices; 2) to evaluate different feeding techniques (food piles, spread food, feeding troughs); 3) to explore the use of biomarkers (e.g., tetracycline, stable isotope markers, radio-active markers) or micro-taggants as a means of further quantifying supplemental food use and the risk of disease transmission.
Potential Transmission of CWD to Other Native Wildlife
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: April 30, 2008
At this point little is known about the rate of decomposition of deer that die from CWD, the type and number of wildlife species that consume deer tissues, the potential role of these species in CWD dynamics, or the effects of CWD infection on these species. However, a variety of mammals including canids, felids, raccoons, opossums, and skunks are likely scavengers on deer carcasses. In addition, it has been reported that deer will also consume animal tissues, including carcass and bone of dead deer. Based on available information, the brain, spinal cord, and the lymphoid tissues of the gut and head are likely to be the greatest source of infectious material. Environmental contamination with prions could affect the health of free-living deer populations and may affect other wildlife species that consume infected deer tissues. This study will determine which wildlife species are likely exposed to CWD contaminated deer tissues and whether these species are currently being affected by CWD within the infected area in Wisconsin. Finding CWD infected animals in these native wildlife species would indicate that other wildlife might be affected by CWD, that CWD was successful in crossing other species barriers, that these species might be useful bio-indicators of environmental contamination with CWD, and would identify a potential route of CWD transmission or exposure to other wild and domestic species. The objectives of this study are: 1) evaluate decomposition of deer carcasses under field conditions; 2) identify the types and variety of wildlife species that are consuming deer tissue and thus might be exposed to CWD infectious prion; 3) collect up to 300 animals from each of the common mammalian scavengers (raccoon, opossum, skunks, and others) and test these animals for CWD infection.
Development of Epizootiologic Models and Related Analytical Support for Chronic Wasting Disease in Wisconsin White-tailed Deer and Other Cervids
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey, Wisconsin Department of Natural Resources
Expected Completion: June 30, 2007
The spread of CWD in wild animals is of great concern. The disease was originally described in captive animals 35 years ago in Colorado. However, over the last five years, CWD has been detected in wild cervids in several surrounding states and Canada. In early 2002, CWD was detected in wild deer in South Dakota, Wisconsin, and now in New Mexico. The recent detection of CWD in the wild white-tailed deer herd in Wisconsin is of particular concern. White-tailed deer appear more susceptible than mule deer and elk to CWD with a greater percentage of the herd becoming infected. Until now, CWD was found in white-tailed deer herds in Colorado, Wyoming, and Nebraska where deer occur at densities of approximately 2-5 deer per square mile. In contrast in Wisconsin, deer are found at 50+ animals per square mile. No one knows how rapidly CWD will spread among white-tailed deer at these densities or what long-term affect this disease will have on a herd of this size (approximately 1.5 million animals).
The objectives of research are: (1) develop strategic and spatially explicit epidemiological models of CWD involving white-tailed deer in Wisconsin and in collaboration with other research studies test and improve these models; (2) in collaboration with other research projects, extend, test, and improve these epidemiological models to incorporate features of CWD found in wild cervids from endemic areas; (3) extend these models to incorporate epidemiology and ecology applicable in the event of TB or FMD outbreaks; and (4) provide statistical and quantitative epidemiological support to the National Wildlife Health Center and the Wisconsin Department of Natural Resources (WDNR) to assist in the evaluation of CWD surveillance, monitoring, and research efforts in Wisconsin.
Genetic Resistance to Chronic Wasting Disease in White-tailed Deer
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: June 30, 2007
This study will investigate the potential association between complement genes involved in the immune response and susceptibility to CWD in free-ranging white-tailed deer in south-central Wisconsin. The complement gene literature will be investigated to identify appropriate gene regions and methodologies for genotyping. Genetic variation will be assayed in complement genes that have been shown or suspected to be important in TSE pathogenesis. The genes to be screened for variation include: C3, C1qa, C1qb, CR1 and CR2. If time and resources permit C1qg and C1qR1 will also be included. This study will be integrated with other research studies using genetic methods to investigate CWD transmission in Wisconsin white-tailed deer.
Specific questions and hypotheses that will be addressed in this research include: 1)Examine whether associations exist between genetic polymorphisms at complement loci and disease presence/absence (H0: presence/absence of CWD is independent of genetic characteristics of complement loci, Ha: presence/absence of CWD is associated with specific genotypes at one or more complement genes); 2) Examine whether associations exist between specific genotypes at complement loci and the pattern of organ involvement (H0: the pattern of organ involvement reflects the normal stage of disease progression, Ha: presence/absence of CWD is associated with specific genotypes at one or more complement genes).
Development of Molecular Assays to Identify Disease Agents (Ribeiroia spp Trematodes and Chytrid, Ichthyphonus, Dermosporidium and Dermocystidium like Fungi) Implicated in Amphibian Die-offs, Population Declines and Malformations.
Investigator: Tim Yoshino, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: January 30, 2007
Over the last 5 years there has been an increased reporting of deformed frogs and massive die-offs of amphibians from natural populations. Diagnostic investigations by NWHC of 100+ die-offs and disease outbreaks in amphibians indicate that the vast majority of those investigated have been caused by three major infectious diseases: Ribeiroia sp (trematode induced malformations); chytrid fungi and a group of fish fungi. A larval trematode (Ribeiroia spp) has been shown experimentally to cause some limb malformations and early death and is often seen in histological examinations of amphibians nationwide. Limb malformations are predicted to decrease fitness and survival and thus recruitment into the adult population. Limb malformations have been reported across large geographic scales (e.g., U.S. to Europe) and from several taxonomic lineages of frogs (www.npwrc.usgs.gov/narcam). Environmental contaminants have been implicated to cause some of the malformations. However, growing evidence indicates that specific malformations such as multiple limbs are more likely caused by infection of tadpoles at specific stages with the larval trematode Ribeiroia spp. Johnson indicated that it was most likely the primary etiological agent responsible for causing malformations in their region of the study located in Santa Clara County, California. It has also been reported that exposure of tadpoles at pre-limb bud stages had up to 97% mortality compared with 12% mortality in unexposed tadpoles under laboratory conditions. This level of mortality in natural populations would occur early in development (pre-limb bud) and could be quite extensive across a site. Ribeiroia spp use snails (Helisoma spp), fish and tadpoles as intermediate hosts. Finding intermediate hosts that are infected is very time consuming and labor intensive. Identification of the larval trematodes in histological section is not always possible given that key morphological characters may not be present in that section. The purpose of this project is to conduct a molecular assay on the tissues of the intermediate hosts and on water samples. This assay would facilitate diagnosis of specimens and could more importantly be used to help characterize sites where infected snails live.
Disease Patterns in the CWD Eradication Zone
Investigator: Michael D. Samuel, USGS, University of Wisconsin-Madison
Funding: U.S. Geological Survey
Expected Completion: December 31, 2006
The spread of CWD in wild animals is of great concern. The disease was originally described in captive animals 35 years ago in Colorado. However, over the last five years, CWD has been detected in wild cervids in several surrounding states and Canada. In early 2002, CWD was reported in wild deer in South Dakota, Wisconsin, and now in New Mexico. The recent detection of CWD in the wild white-tailed deer herd in Wisconsin is of particular concern. White-tailed deer appear more susceptible than mule deer and elk to CWD with a greater percentage of the herd becoming infected. Until now, CWD was found in white-tailed deer herds in Colorado, Wyoming, and Nebraska where deer occur at densities of approximately 2-5 deer per square mile. In contrast in Wisconsin, deer are found at 50+ animals per square mile. No one knows how rapidly CWD will spread among white-tailed deer at these densities or what long-term affect this disease will have on a herd of this size (approximately 1.5 million animals).
Objectives for this research are: 1) determine the distribution of CWD in the Eradication Zone, 2) determine the age/sex/clinical relationship of deer to prevalence of disease, 3) determine the vulnerability of CWD infected deer to harvest, and 4) evaluate how and when CWD is transmitted within and among social groups of white-tailed deer.