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EXPOSURE OF AMPHIBIANS TO SEMI-VOLATILE ORGANIC COMPOUNDS IN THE SIERRA NEVADA MOUNTAINS AND CALIFORNIA CASCADES: RELATIONSHIP BETWEEN TADPOLE TISSUE AND SEDIMENT CONCENTRATIONS
Citation:
STANLEY, K., R. HUBER, C. DAVIDSON, D. F. BRADFORD, N. G. TALLENT-HALSELL, AND S. SIMONICH. EXPOSURE OF AMPHIBIANS TO SEMI-VOLATILE ORGANIC COMPOUNDS IN THE SIERRA NEVADA MOUNTAINS AND CALIFORNIA CASCADES: RELATIONSHIP BETWEEN TADPOLE TISSUE AND SEDIMENT CONCENTRATIONS. Presented at SETAC, Milwaukee, WI, November 11 - 15, 2007.
Description:
Pesticides and other semi-volatile organic compounds (SOCs) undergo regional and longrange atmospheric transport. One such example is the transport of current-use pesticides from the intensely cultivated Central Valley of California into the adjacent Sierra Nevada and Cascade Mountains. Amphibian species, including the mountain yellow-legged frog (Rana muscosa) and the Cascades frog (Rana cascadae), are declining in these ranges and pesticides have been implicated in these declines. Upon entering mountain ecosystems, pesticides and other SOCs may be deposited into the aquatic environment where they may accumulate in the sediment. Tadpoles live in close contact with the sediment; this may be an important route of exposure for these organisms. Tadpole and sediment samples were collected concurrently from 28 lakes in the Sierra Nevada Mountains and 32 lakes in the Cascade Mountains in the summer of 2005. Pacific tree frog tadpoles (Pseudacris regilla) were collected as a surrogate species for mountain yellow-legged frog at all Southern Sierra sites and at Cascades sites where the Cascades frogs are no longer common. Using methods developed in our laboratory, tissue and sediment samples were processed and analyzed for over seventy SOCs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and several classes of pesticides. Of these, the most commonly detected compounds in both matrices included the widely used pesticides endosulfan and dacthal. The relationship between SOC concentrations in the tadpole tissue and sediment will be discussed and correlations with regional pesticide use in California will be presented.