title: Gonadal abnormalities in frogs (Lithobates spp.) collected from managed wetlands in an agricultural region of Nebraska, USA.
abstract: Nebraska's Rainwater Basin (RWB) provides important wetland habitat for North American migratory birds. Concern exists that pesticide and nutrient runoff from surrounding row-crops enters wetlands degrading water quality and adversely affecting birds and wildlife. Frogs may be especially vulnerable. Plains leopard (Lithobates blairi) metamorphs from RWB wetlands with varying concentrations of pesticides were evaluated for a suite of biomarkers of exposure to endocrine active chemicals. Froglets had ovarian dysgenesis, high rates of testicular oocytes, and female-biased sex ratios however, there was no clear statistical association between pesticide concentrations and biomarkers. Data interpretation was hindered because timing and duration of exposures were unknown and due to an incomplete understanding of L. blairi sexual development. Emphasis is on describing the complex developmental biology of closely-related leopard frogs, how this understanding can explain RWB L. blairi anomalies, and the need for sampling at the appropriate life stage.
authors.affiliation: Columbia Environmental Research Center, U.S. Geological Survey, 4200 New Haven Rd., Columbia, MO 65201, USA. dpapoulias@usgs.gov
authors.forename: Diana M
authors.initials: DM
authors.lastname: Papoulias
authors.forename: Matt S
authors.initials: MS
authors.lastname: Schwarz
authors.forename: Lourdes
authors.initials: L
authors.lastname: Mena
mesh_terms: D000383:Agriculture; D000818:Animals; D017753:Ecosystem; D004784:Environmental Monitoring; D006066:Gonads / Q000002:abnormalities*; D009329:Nebraska; D010575:Pesticides / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D011898:Ranidae / Q000002:abnormalities / Q000378:metabolism / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D053833:Wetlands
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical