M9 PM Multiple Stressors in Amphibian and Reptile Ecotoxicology
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 339-340

(MCC-1117-887315) Investigating Pesticide Exposure Pathways in Amphibian Habitat of the Sierra Nevada Mountains.

McConnell, L¹, Drakeford, L¹, Fellers, G², Sparling, D³, Cowman, D⁴, Kleeman, P², Harner, T⁵, Bidleman, T⁶, ¹ USDA-ARS, Beltsville, MD, USA² Western Ecological Research Center, USGS, Point Reyes, CA, USA³ Southern Illinois University, Carbondale, IL, USA⁴ Texas A&M University College, College Station, TX, USA⁵ Environment Canada, Downsview, ONT, Canada⁶ Environment Canada, Egbert, ONT, Canada

ABSTRACT- Wildlife biologists have observed severe declines in several amphibian populations in the Sierra Nevada Mountains of California, USA. Disease, habitat loss, UV (ultraviolet) radiation, predation, and pollution are factors that have been hypothesized to be involved with the disappearance of amphibians over the last two decades. A number of recent studies have also illustrated the cold-trap effect occurring in alpine regions with respect to organic pollutants such as pesticides. Samples of water (n=130), sediment (n=104), snow (n=36), air (n=72), and adult Hyla Regilla (n=89) were collected from a number of locations along the Sierra Nevada Mountain range during 2000-2005 as part of a series of related studies to determine the exposure of tree frogs to agricultural pesticides and other legacy organochlorine insecticide contaminants. Initial results suggest that agricultural pesticides are deposited to the alpine amphibian habitat via snow and other atmospheric deposition processes. However, only the more persistent organochlorine pesticides were detected in the sediment, water, and amphibian tissue samples collected during the summer months while sites are accessible. Environmental conditions present in typical alpine amphibian habitat during the summer months (warm temperatures, high UV radiation, shallow ponds with significant animal and plant biomass) likely lead to rapid degradation of most current use pesticides.

Key words: amphibians, pesticides, sierra nevada mountains, organochlorine