PARENT SESSION

Conservation 5 -- Session Chair: William Zielinski-- University Center, Kate Buchanan Room

SELENIUM ACCUMULATION IN SMALL MAMMALS ON RETIRED AGRICULTURAL LANDS IN THE SAN JOAQUIN VALLEY, CALIFORNIA. Curtis E. Uptain¹, Stephen L. Lee², Steve R. Messer¹, Darren P. Newman¹ and Patrick A. Kelly¹. ¹ California State University Stanislaus, Endangered Species Recovery Program, 1900 Gateway Blvd., Fresno, Ca., USA; ² United States Bureau of Reclamation, 1243 N. Street, Fresno, Ca., USA.

ABSTRACT- Elevated groundwater levels and high concentrations of selenium in the groundwater and in the soil characterize extensive tracts of farmland in the San Joaquin Valley of central California. Up to 80,000 hectares of this land may be retired from irrigated agriculture to reduce problems associated with the accumulation and disposal of selenium-tainted agricultural drain water. Since 1999 we have been exploring the potential to restore native plant and animal communities to these lands. One primary concern is the potential for bioaccumulation of selenium because of its potential for detrimental effects on wildlife. Accordingly, over a 5-year period we have been monitoring selenium levels in groundwater, soils, and biota on two study sites that have been retired from irrigated agriculture. Selenium levels in body and liver tissues for two small mammals species, Peromyscus maniculatus and Sorex ornatus, are within acceptable limits indicating that bioaccumulation at the population level may not be problematic. However, some body and liver samples contained selenium levels high enough to warrant concern, suggesting the need for continuation of contaminant monitoring.

KEY WORDS: Agriculture, Selenium