<p>  </p> <p>Over the past two decades, emerging fungal pathogens have been reported in numerous groups ranging from mammals to key crop species across the globe. To combat the rise of these fungal pathogens in industrial agriculture, fungicides have been developed and subsequently applied en masse. Despite their growing usage, research examining the effects of these anthropogenic contaminants on natural systems is severely limited compared to other major classes of pesticides. Of particular concern are their impacts on aquatic systems, which can be especially at risk due to their proximity to agriculture. Herein I used a tiered approach to assess the impacts of this class of pesticides on aquatic ecosystems using amphibians as model system. In the first chapter, I assessed the acute toxicity of two widely applied fungicides, pyraclostrobin and chlorothalonil, to six different species of amphibians commonly found in the Midwest. My results showed that these fungicides are very acutely toxic to several species of amphibians at levels within the expected environmental concentration (EEC). In the second chapter, I examined the impacts of long-term low-dose exposure of pyraclostrobin on the growth, development, and activity levels of three species of amphibians. Despite the acute toxicity of pyraclostrobin, sublethal effects of the fungicide were rather limited with only minor effect on growth and activity. In the third chapter, I investigated the effects of fungicide exposure on host-parasite interactions using trematodes and American Bullfrog tadpoles. I found that in all treatments pyraclostrobin increased parasite loads from ~3 to 8 times compared to control tadpoles. Additionally, parasite loads were approximately 2 times higher in tadpoles with the continued fungicide exposures compared to those tadpoles that were moved to fresh water following initial fungicide exposure. Finally, my fourth chapter investigated the impact of pyraclostrobin and chlorothalonil application regime on community-level interactions under semi-natural conditions. While chlorothalonil had limited effects on the community, I found that pyraclostrobin was acutely toxic to Gray Treefrogs at environmentally relevant concentrations and these effects were stronger with more frequent applications. Collectively, my research has demonstrated that fungicides can be acutely toxic to amphibians at EECs under laboratory and semi-natural conditions. Additionally, they have the potential to alter disease dynamics by increasing infection risk. Given our increasing usage of fungicides to control emerging fungal pathogens, a greater emphasis on understanding the environmental implications of this management strategy is needed to inform ecological risk assessments. </p>

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Twenty-nine (Group One, June 8,1995) grass carp (Ctenopharyngodon idella) and five (Group Two, April 18, 1996) grass carp were radio-tagged to monitor movement patterns and habitat preferences on North Lake, a 335 hectare multi-use reservoir located in Irving, Texas. Overall fish mean Average Daily Movement (ADM) rates were 49.2 meters/day (during Half One, 6/8/95-11/30/95) and 5.3 meters/day (during Half Two, 12/14/95-6/6/96). Aquatic macrophtye distribution data were obtained. Radio-tagged grass carp were located in Hydrilla verticillata infested areas increasingly throughout the study, however, percent frequency of Hydrilla along 15 transects did not decrease. Radio-transmitters were equipped with temperature-sensors (10-35 Celsius range). Results indicated that radio-tagged grass carp showed no avoidance of areas of North Lake with elevated water temperatures. Radio-tagged grass carp dispersed quickly from stocking point, then moved into littoral areas infested with Hydrilla. After an initial movement period, most fish remained in a localized area.

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<p dir="ltr">North American beaver are ecosystem and habitat altering mammals with a wide distribution in North America. Beaver are associated with bodies of fresh water while utilizing riparian habitat by foraging on woody and herbaceous, terrestrial and aquatic vegetation, as well as creating lodges, dams, dens, and scent mounds. Chain O’Lakes State Park was chosen as a study area for surveying beaver activity and woody species communities. The aim of the study was to better understand the relationship between beaver, and specifically, the woody vegetation in their foraging and home range. There is a large swath of habitat that beaver can utilize and alter within Chain O’Lakes State Park including the lakes, streams, and forests that attract visitors. The factors that have been found to influence beaver utilization in Chain O’Lakes State Park (and North America at large) are woody species community composition, abundance of heavily preferred woody species, as well as a combination of both an absence of predators and an abundance of aquatic vegetation. Based on the distribution of heavily, occasionally, and rarely preferred woody species across the understory (new individuals) and overstory (mature individuals) stratum an inference can be made that most of the riparian habitat around the lakes will continue to and/or shift into a higher proportion of species that beaver heavily select. A minority of the habitat shall shift away from those species and towards rarely and/or occasionally selected species. I will provide USDA APHIS Wildlife Services that play a wildlife management role in Chain O’Lakes State Park with the survey information detailing how beaver and their structures interact with the ecosystem, hypothesized methods for preserving the woody species that are targeted by beaver foraging within the park, and supplementary information that may aid in maintaining the riparian habitats for the benefit of park’s biodiversity and wildlife persistence while continuing to provide an enriched experience within Northwest Indiana with the potential to inform the greater collection of parks and maintained land at large.</p>

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