Meeting Abstract

132.7  Tuesday, Jan. 7 14:45  Amphibians Stressed By Agricultural Land Use Have Altered Immunity and Increased Parasitic Infections FALSO, P.G.*; GALLIPEAU, S.; HAYES, T.B.; Slippery Rock University; University of California, Berkeley; University of California, Berkeley paul.falso@sru.edu

Changing environmental conditions have dramatically decreased global amphibian populations. Increases in susceptibility to pathogens may result from stressful habitat conditions and subsequent disruption of immune response. Amphibian populations in agricultural regions are subject to diverse environmental stressors resulting from human habitat manipulation. In the current study we examined the connection between land use, physiology, and disease ecology of amphibian populations in three agricultural watersheds in California, USA. The invasive American bullfrog (Lithobates catesbeianus) was used as a surrogate model to examine possible effects of agricultural contaminants and habitat disruption on sensitive native amphibian populations in the Salinas, San Joaquin, and Sacramento River systems. We analyzed the endocrine and immune function of bullfrogs collected at sites along a gradient of agricultural land use within the three river systems. Elevated plasma stress hormone levels (corticosterone) and altered white blood cells (differentials and activity) were observed in bullfrogs collected from agricultural sites compared to sites upstream of agriculture. Additionally, bullfrogs collected in an agricultural site had increased infections with Echinonstoma spp parasites in comparison to a reference site upstream. Our study indicates that altered environmental conditions in agricultural regions may lead to endocrine and immune disruption of amphibians, and result in increased disease and further population declines.