Grant Winners
2010 Conference Travel Grant - Taegan McMahon
A $500 conference travel grant was awarded to Ms. Taegan McMahon, a Ph.D. Candidate in the Department of Integrative Biology at the University of South Florida, to present her lecture entitled "Chlorothalonil: an immunomodulatory and deadly fungicide to amphibians" at the Joint Meeting of Herpetologists and Ichthyologists in Providence, Rhode Island July 7-12, 2010.
Title: Chlorothalonil: an immunomodulatory and deadly fungicide to amphibians
Authors: Taegan McMahon, Neal Halstead, Steve Johnson, Thomas R. Raffel, John M. Romansic, Patrick W. Crumrine, Raoul K. Boughton, Lynn B. Martin, and Jason R. Roh
Abstract
Agrochemicals have been implicated in amphibian declines, but most tested agrochemicals do not kill amphibians at concentrations found commonly in the environment. However, many of the ~100,000 registered chemicals have not been thoroughly tested on amphibians. One understudied pesticide is chlorothalonil, the most commonly used synthetic fungicide in the U.S. We reared Rana sphenocephala and Osteopilus septentrionalis in outdoor mesocosms for five weeks in the presence or absence of one and two times the expected environmental concentration (EEC; 164 µg/L) of chlorothalonil. The EEC was associated with 99.5% and 97.8% mortality of R. sphenocephala and O. septentrionalis, respectively, and 2x the EEC caused 100% mortality. We then conducted three static renewal, dose-response experiments on O. septentrionalis, Hyla squirella, H. cinerea, and R. sphenocephala. The EEC of chlorothalonil caused 100% mortality of all species within 24 hours, half the EEC killed 100% of R. sphenocephala, and the lowest concentration tested, 0.0164 µg/L, caused significant mortality. The dose-response was non-monotonic, with only low and high concentrations causing significant mortality, these concentrations were also associated with elevated Corticosterone levels. Additionally, chlorothalonil concentration was negatively associated with liver health and numbers of immune cells in the liver (<16.4 µg/L). Given that chlorothalonil: killed nearly every tadpole at the EEC, caused significant mortality four orders of magnitude below the EEC, induced immunosuppression at environmentally common concentrations, and has been regularly detected at or below the EEC in regions where amphibian are going extinct, chlorothalonil exposure has the potential to directly and indirectly cause amphibian declines.
Thoughts from the winner
"This presentation will help enlighten people about the harmful effects of the most commonly used synthetic fungicide (second most commonly used fungicide) in the United States on amphibian populations. It highlights the fact that even when some pesticides are used at or below the recommended "safe" levels, they can completely decimate amphibian populations. People use pesticides like chlorothalonil on their gardens and many have no idea how harmful it can be not only to themselves, but also to the environment. We've not found the no observable effect concentration for this commonly used chemical; in fact 1000x below the EEC it is still deadly to amphibians. I feel really strongly that research which shows people that their behaviors (for example pesticide use) can have direct effects on the environments health is extremely impactful and pertinent."
Note: Trade names for chlorothalonil include Bravo, Chlorothalonil, Daconil 2787, Echo, Exotherm Termil, Forturf, Mold-Ex, Nopcocide N-96, Ole, Pillarich, Repulse, and Tuffcide. The compound can be found in formulations with many other pesticide compounds.
2009 Conference Travel Grant - Kris Kaiser
A $500 conference travel grant was awarded to Ms. Kris Kaiser, a Ph.D. Candidate in the Department of Ecology & Evolutionary Biology at UCLA, to present her lecture entitled "When sounds collide: Effects of anthropogenic noise on frog calling behavior" at the Joint Meeting of Herpetologists and Ichthyologists in Portland Oregon July 22-27, 2009.
Title: When sounds collide: Effects of anthropogenic noise on frog calling behavior
Authors: Kristine Kaiser, Menemsha Alloush, Robin M. Jones, Susanne Marczak, Katherine S. Martineau, Mark V. Oliva, Peter M. Narins
Abstract
Differential susceptibility of amphibians to habitat degradation and fragmentation is not well understood. Existing studies of amphibian response to anthropogenic change typically correlate with or model life history traits; few relevant behavioral data exist. Among the most poorly understood effects of habitat change are those resulting from an increased complexity of the acoustic environment, e.g., from the presence of anthropogenic noise. Here we test the hypothesis that car engine noise differentially affects disturbance-tolerant and disturbance-sensitive species. We carried out playback experiments with anthropogenic noise on seven frog species in Belize. We also chose one focal species, Dendropsophus microcephalus, to determine if this noise affected chorus tenure for individuals, or length of chorus. We used mark-recapture at two ponds: one where noise was broadcast each night and one where no noise was ever played (control). We found that species respond to noise differentially, with the most forest-dwelling species being least likely to call in the face of noise. Chorus tenure and number of times recaptured were both significantly greater at the control pond. Lengths of nightly chorus were equivalent at the beginning of the study, but were significantly different after two months. Taken together, these results suggest that the acoustic landscape acts as any other environmental parameter, shaping which species will persist, and which species may perish. While frogs are known to employ a suite of mechanisms to cope with biotic noise, this is the first investigation demonstrating chorus-level effects of anthropogenic acoustic disturbances in amphibians.
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These awards are funded by members of the public who share our concerns. The government does not provide SAVE THE FROGS! with any monetary assistance and thus we depend on you! Our goal is to provide as many of these awards as possible, as each award contributes significantly to amphibian conservation, but we can only do so with your support. Thanks!
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