title: Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture.
abstract: Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of two native amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while reference wetlands receive water from overland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected in water and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1,500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and implementing conservation and management actions for these and similar wetlands in agriculturally dominated landscapes.
authors.affiliation: US Geological Survey New Jersey Water Science Center, Lawrenceville, NJ, USA. Electronic address: ksmall@usgs.gov.
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Smalling
authors.affiliation: Department of Natural Resource Ecology and Management, Iowa State University, Ames, IA, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Reeves
authors.affiliation: US Geological Survey, Fort Collins Science Center, Fort Collins, CO, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Muths
authors.affiliation: US Geological Survey, Fort Collins Science Center, Fort Collins, CO, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Vandever
authors.affiliation: US Geological Survey, Colorado Water Science Center, Lakewood, CO, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Battaglin
authors.affiliation: US Geological Survey, California Water Science Center, Sacramento, CA, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Hladik
authors.affiliation: US Geological Survey, Iowa Cooperative Fish and Wildlife Research Unit, Ames, IA, USA.
authors.forename: Clay L
authors.initials: CL
authors.lastname: Pierce
mesh_terms: D000383:Agriculture; D000818:Animals; D001280:Atrazine / Q000378:metabolism; D004784:Environmental Monitoring; D007484:Iowa; D010575:Pesticides / Q000378:metabolism*; D011894:Rana pipiens / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*; D053833:Wetlands
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical; D001280:Atrazine
keywords: Agricultural landscape; Amphibians; Bioaccumulation; Habitat quality; Nutrients; Pesticides