Surveys of amphibians, abnormalities, pathogens, triazines, breeding-site characteristics, and reptiles in five areas managed by the National Park Service and the U.S. Fish and Wildlife Service in the Upper Midwest, 2002-2007

Sadinski, W; Roth, M

We and our colleagues from the U.S. Geological Survey (USGS) Upper Midwest Environmental Sciences Center (UMESC) in La Crosse, Wisconsin, and Minnesota Water Science Center in Mounds View, Minnesota, conducted the work described in this report. We worked on lands managed by the U.S. Department of the Interior (DOI) in support of the goals of the USGS Amphibian Research and Monitoring Initiative (ARMI) and the U.S. National Park Service (NPS) Inventory and Monitoring Program (IMP), especially as they applied to the Midwest Region of ARMI (ARMI-MR) and NPS Great Lakes Inventory and Monitoring Network (GLKN). These goals were to assess the statuses of amphibian populations on DOI lands relative to key environmental factors in ARMI Midwest Region and to inventory Voyageurs National Park (VOYA), the St. Croix National Scenic Riverway (SACN), and the Mississippi National River and Recreation Area (MISS) for the presence of amphibian and reptile species. Thus, we designed surveys to meet the goals of both programs. Our principal objectives throughout these studies were to 1) conduct visual-encounter and call surveys for amphibians at potential breeding sites in VOYA, the SACN, the UMR, and the NS, and targeted searches for amphibians in the MISS, 2) conduct visual-encounter surveys for reptiles, especially turtles, in the vicinity of amphibian breeding sites in VOYA and the SACN, and to a lesser extent, the MISS, 3) analyze amphibian survey data across management units and years using information-theoretic models to estimate occupancy and the probability of detection in relation to site-specific and sampling-specific characteristics, 4) sample water from amphibian breeding sites in VOYA, the SACN, the UMR, and the NS and analyze for the presence of triazine herbicides, 5) measure gross physical abnormalities among amphibian metamorphs at breeding sites in VOYA, the SACN, the UMR, and the NS, and 6) sample amphibian populations in VOYA, the SACN, and the UMR for the presence of pathogens, parasites, and symptoms of disease. We surveyed in VOYA and the SACN from 2002-2007, in MISS during 2003 and 2004, in the UMR from 2002-2005, and in the NS from 2003-2005. We observed most of the amphibian and reptile species we expected to find in each management unit given known historical distributions, species we targeted, resource limitations, and the methods we employed. Estimates of occupancy and probabilities of detection varied widely for amphibian species sampled during the day across VOYA, the SACN, the UMR, and the NS. Of the 523 water samples we collected at amphibian breeding sites across management units and analyzed for the presence of triazines, 30.8% were below the detection limit of 0.050 ppb, mostly in the SACN and VOYA. We observed gross physical abnormalities in less than 5% of the metamorphs sampled in VOYA, the SACN, the UMR, and the NS. We observed the potentially deadly chytrid fungus, Batrachochytrium dendrobatidis, on green frogs and mink frogs from practically all sites where we sampled them in VOYA (88%) and the SACN (100%) during 2006, but at fewer sites on northern leopard frogs in the UMR (25%). Most individual, apparently healthy amphibians we submitted for health screening were afflicted with parasites of one sort or another, ranging from flukes to trematodes. Ribeiroia ondatrae, a parasitic trematode we observed, is considered a primary inducer of gross physical abnormalities in amphibians.

Surveys of amphibians, abnormalities, pathogens, triazines, breeding-site characteristics, and reptiles in five areas managed by the National Park Service and the U.S. Fish and Wildlife Service in the Upper Midwest, 2002-2007

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