Midwest Fish & Wildlife Conference 2019

AUTHORS: Matthew C. Allender, Ellen Haynes, Marta Kelly – Wildlife Epidemiology Laboratory, University of Illinois; Sarah J. Baker, Wildlife Epidemiology Laboratory and Illinois Natural History Survey, University of Illinois

ABSTRACT: Snake fungal disease (SFD), caused by the fungus Ophidiomyces ophiodiicola, emerged as a wildlife disease threat over the last 10 years and specifically may threaten the conservation of free-ranging Eastern Massasaugas. Historical records and museum collections have now indicated that SFD was present in some populations in Illinois at least a decade before its description in the literature. The disease syndrome involves clinical signs ranging from minor raised and thickened scales to severe crusts or ulcers on the head and body and can cause death in severe cases. The disease has been found to affect at least 31 snake species. As part of ongoing surveillance for SFD, the Wildlife Epidemiology Lab routinely tests samples for the presence of O. ophiodiicola using qPCR. Since 2013, we have tested over 2000 snake samples from 69 species. In total, 616 positive samples have been recorded across 31 species in 11 states. Despite the apparent sensitivity of pit vipers, only 12.5% (n=99/693) of Eastern massasaugas (Sistrurus catenatus) were positive, whereas nearly 60% (n=218/365) of water snakes (Nerodia sp.) were positive for O. ophiodiicola. Host factors, such as hematology and protein electrophoresis have demonstrated individual Eastern Massasaugas respond immunologically, but the basis for disease protection is unknown. This presentation will synthesize historical and existing knowledge of SFD in Eastern Massasaugas and plans for future efforts. Characterizing the epidemiology of this disease can improve future surveillance and management efforts that may mitigate its effects on snake populations worldwide.

AUTHORS: Michelle Carstensen, Erik C. Hildebrand, Dawn Plattner, Margaret Dexter – Minnesota Department of Natural Resources; Arno Wünschmann, Anibal Armien – University of Minnesota-Veterinary Diagnostic Laboratory

ABSTRACT: Minnesota’s moose (Alces alces) are dying at rates much higher than elsewhere in North America. Moose have been nearly extirpated from the northwestern part of the state and aerial surveys indicate the northeastern population has declined 55% over the past decade. In 2013, a new study began to determine cause-specific mortality of adult moose in northeastern Minnesota by using GPS-satellite collars to get rapid notification of mortality events and recover carcasses within 24 hours of death. A total of 173 moose were collared over 3 years with annual non-hunting mortality rates of 19%, 12%, 15%, 13% and 14% in 2013-2017, respectively, and an overall mean of 14.4%. In total, 57 moose have died from non-hunting sources of mortality and 3 moose were legally harvested. Response times from mortality notification to arrival at the carcass were within 24 hours for 65% of death events. Most causes of mortality were health-related (65%), which included parasites (30%; e.g., winter ticks, brainworm, and liver flukes), bacterial infections (20%), accidents (3%), calving (2%) and other undetermined health issues (10%).The remainder was wolf-related (30%), with predisposing health conditions identified in nearly half of these moose.  Legal harvest accounted for 5% of moose deaths. During the same time period, we also necropsied anecdotal moose deaths (n=91) across northern Minnesota, which included vehicle or train collisions, sick, and found dead animals. Parelaphostrongylus tenuis was confirmed in 42% of these cases, which is nearly twice the rate of detection of this parasite as in the collared moose studied during the same time period. 

AUTHORS: Macayla Greider, Jeffrey Dimick – Aquatic Biomonitoring Laboratory, University of Wisconsin-Stevens Point; Dr. Justin VanDeHey, Dr. Shelli Dubay – College of Natural Resources, University of Wisconsin-Stevens Point

ABSTRACT: Mermithid nematodes are generally considered as biological control agents for pest species like Anopheles, but also may influence Trout (Salmonidae) food sources because they cause reproductive failure and mortality in both midge (Chironomidae) larvae and mayfly (Ephemeroptera) nymphs.  However, much remains unknown about the mermithid life cycle and factors affecting their distribution. Our objectives were to determine if the prevalence of mermithid infections differed (1) between hosts with different feeding strategies, (2) in streams with different macroinvertebrate and fish communities, and (3) with stream flow rates. We hypothesized that (1) filter feeding midges would have higher prevalence of midge infection because filter-feeders passively ingest eggs whereas other midges seek out specific prey, (2) Trout streams would have fewer mermithids, and (3) stream flow would not be related to mermithid prevalence. Mermithid prevalence was assessed in samples collected from 48 streams during 2010-2014 from four northwestern Wisconsin counties. Infection was determined by observation of mermithids within midge bodies. Midges were identified to species to determine feeding behavior and distinguish filter feeders from non-filter feeders. Significantly lower proportions of mermithids were present in Trout streams than non-Trout streams, but no significant differences were present between mermithid presence and either HBI score or stream velocities. Chi-square analysis indicated no significant difference in prevalence between filter feeding and non-filter feeding groups; however, shredders had higher mermithid prevalence than other feeding groups. This research will provide insight into some aspects of mermithid life cycles and host selection.

AUTHORS: Bridget K.G. Brown, Ohio State University

ABSTRACT: White-nose Syndrome (WNS) was discovered in the United States in New York in 2006. It slowly made its way across the country and was found in Ohio in 2011. Substantial declines were reported starting in 2012 in Ohio's two largest hibernacula, the Preble and Lawrence County mines. However, there was little information on the impact WNS was having on Ohio’s summer populations. In order to determine this, the Ohio Division of Wildlife instigated a mobile bat acoustic survey. The goal of this project was to noninvasively monitor the summer bat populations in Ohio and determine the negative effects (e.g. population declines and loss of species diversity) that WNS may be having statewide. This program has grown to include 44 acoustic routes with over 100 volunteers assisting. Survey results were compared annually to monitor changes in bat abundance along each route. There was evidence of declines, although not statistically significant, in state bat abundance overall from 2011 to 2017. This is likely as a result of WNS in combination with other various threats to bats (e.g. wind turbines and habitat loss). There was a significant increase in abundance between 2014 and 2017 (p=.014050). Increases from 2014 could represent beginning recoveries in Ohio’s bat populations or a change in species composition across the post-WNS landscape. Continuing this project into the future could allow for further understanding of the status of Ohio's bat populations.

AUTHORS: Dan Molloy, Molloy & Associates, LLC

ABSTRACT: Dreissena mussels pose a significant challenge to infrastructures. One key element contributing to this challenge is the lack of a practical method for large-scale control of populations once they become established throughout a water body. As a result, facilities drawing water from such water bodies are subjected to constant reinfestation. Although concerns exist about environmental impacts of molluscicides, it is the prohibitive total project cost of open-water control programs that currently eliminates them as a mitigation option. Total project cost includes not only the molluscicide and its application throughout the entire water body, but also a myriad of other expenses often required in the overall control program, such as fund raising, administration, regulatory approval, post-treatment mussel mortality monitoring, report writing, etc. The research project reported herein offers a potential solution to this seemingly intractable problem of prohibitively high control program expense. The key to the low cost of this proposed control approach is that it does not require treatment of the entire water body. In contrast to traditional control programs: 1) only a minuscule portion of the infested water body’s volume would be treated (“seeded”) with the control agent; and 2) the control agent would subsequently amplify itself and self-spread throughout the water body. There is only one type of control agent capable of doing that – a live one, a biological control agent. This presentation describes the research conducted in the first year of a multi-year project to find such a control agent. The project is based in Eurasia and specifically designed to find a hypervirulent (i.e., extremely lethal), highly-specific dreissenid parasite that one day (following years of comprehensive environmental safety studies) would be introduced into North American water bodies where it will leave a trail of dead dreissenids in the path of its spread.

AUTHORS: Jeremy M. Rayl, Marta Kelly, Michelle Beermann, Matthew C. Allender – Wildlife Epidemiology Laboratory, College of Veterinary Medicine, University of Illinois Urbana-Champaign

ABSTRACT: Eastern box turtles (Terrapene carolina carolina), a declining species across most of its range, are threatened by disease events including ranaviral disease, mycoplasmosis, and herpesviral infections, but individual host hematologic responses are largely unknown. At a site with known amphibian and box turtle ranavirus outbreaks, a cohort of eastern box turtles (N=36) was investigated using radio telemetry. Location and temperature data were collected over two active seasons and brumation periods (2016-2018). Bi-weekly, turtles were sampled for blood and oral-cloacal swabs for hematology and pathogen detection. All turtles were negative for ranavirus over the study period. Total white blood cells, heterophils, lymphocytes, eosinophils, and monocytes were greater in females compared to males. Total solids, total white blood cells, heterophils, and lymphocytes showed decreasing patterns in both sexes during the active season. Home ranges and average daily movement were not significantly predicted by hematology or pathogen detection. These data add to the long-term health monitoring of eastern box turtle populations in central Illinois. With repeated measures, we have an increased ability to find complex spatiotemporal relationships between box turtle movement, hematology, and pathogens. In conjunction with long-term cross sectional surveys, a more complete picture of box turtle health related to these variables can be developed with this site as an example within central Illinois. 

AUTHORS: Megan Niner, University of Toledo; Dr. Carol Stepien, NOAA Pacific Marine Environmental Lab; Dr. Doug Leaman, Wright State University

ABSTRACT: The viral hemorrhagic septicemia virus (VHSv) is a fish virus responsible for occasional fish kills in the Laurentian Great Lakes in the last fifteen years. Substrain IVb is a recently emerged pathogen with an unusually large host range of over 30 species of fish, both of native and non-native status. With new outbreaks once again occurring, more insight into the evolutionary trends of this fish pathogen could help predict future trends. This study provides a unique examination of a wildlife pathogen in a natural setting. We sequenced the full genome of multiple VHSv-IVb isolates collected in the fifteen years following its emergence to examine evolutionary trends. For these 30 isolates, we compare and contrast differences in nucleotides, amino acids, mutation sites, and the number of transvisions and transversions to elucidate possible patterns across time. To understand how observed changes in sequences may affect the course of infection, further testing of three selected full genomes from Lake Erie were used in a variety of cell culture studies. Our selected isolates were haplotypes “v” (H31, round goby, 2015), “w” (B09, gizzard shad, 2016), and “w4” (G61, smallmouth bass, 2016). Cell experiments included testing for differences in pathogenicity from the original isolate haplotype “a” (MI03GL, 2003), examining cytopathogenicity, virus production, and immune response stimulation. All three new isolates appeared to behave similarly to “a” despite being recovered more than a decade later.

AUTHORS: Jacob A. Shurba, Kali Rush, Jacob Straub – University of Wisconsin-Stevens Point

ABSTRACT: Since September 2017, a study was conducted to examine hen and brood survival rates of Wood Ducks (Aix sponsa) in central Wisconsin. The capturing of wood ducks during the breeding season required use of decoy traps using captive wood duck hens. These captive ducks were purchased from two game farms in the Midwest. Captive decoy hens were placed in traps to attract breeding wood ducks. In March 2018, a small number of the decoy ducks began dying with no clinical signs to diagnose what was causing the mortality. In this study, we reviewed common diseases of waterfowl, the husbandry requirements for captive waterfowl species, and produced potential explanations as to what caused captive duck mortality, as well as recommendations for future studies. We collected data based on the differences in how our ducks were housed compared to recommendations in the literature. We also reviewed the inconclusive pathology reports from the deceased ducks and compared results to common diseases found in waterfowl. We found that the conditions our decoys ducks were kept in could be improved. A combination of living conditions and the adverse effects of being a decoy bird played a significant role in the mortality of these decoy ducks. Recommendations for future studies include a change of living condition to decrease the amount of stress placed on the decoys, and to lessen the amount of time a decoy duck is spending in the trap.