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

(COW-1117-773885) Cholinesterase inhibition in metamorphs and tadpoles in the Sierra Nevada Mountains, CA.

Cowman, D.¹, Sparling, D.², Fellers, G.³, McConnell, L.⁴, Lacher, T.^{1, 5}, ¹ Texas A&M University, College Station, Texas, USA² Southern Illinois University, Carbondale, Illinois, USA³ USGS Western Ecological Research Center, Point Reyes, California, USA⁴ USDA Agricultural Research Service, Environmental Quality Lab, Beltsville, Maryland, USA⁵ Conservation International, Washington, D.C., USA

ABSTRACT- Declines of native ranid frog populations in the Sierra Nevada mountains may be linked to aerial deposition of pesticides originating from the Central Valley of CA. Pseudacris regilla (Pacific chorus frog) hatchings were translocated (with controls in each park) and placed in cages in sites (approximately 7-8000 ft. in elevation) located in Lassen, Yosemite, and Sequoia National Parks. Cholinesterase was measured in tadpoles collected at 28 days and in juvenile frogs collected upon metamorphosis. Animals were staged according to Gosner; then grouped in the following categories: (PL) prelimb (24-26); (LB) limbbud (27-34); (EHL) early hind limb (35-36); (MHL) middle hind limb (37-39); (LHL) late hind limb (40-41); (meta) metamorph (42-46). ANOVA showed overall differences (p<.0001) between ChE values for metas and all other groups; between LHL and all other groups; there were no differences between MHL, EHL, LB. and PL. ChE values for metas and tadpoles raised at Lassen National Park (reference site) were significantly higher (p<.0001) than values for metas and tadpoles raised at Sequoia and Yosemite National Parks regardless of origin. ChE inhibition can be an indicator of organophosphate insecticide exposure. Effects noted in P. regilla may be magnified in long lived ranid species that are positively correlated with the presence of P. regilla.

Key words: frogs, pesticide, cholinesterase, tadpoles