The biological and physiological effects of excess copper in juvenile mallards (Anas platyrhynchos): an investigation of the toxicity of acid mine drainage in waterfowl

1999 Fall. ; Includes bibliographical references (pages 126-132). ; Covers not scanned. ; Print version deaccessioned 2019. ; In the early 1990's, concentrations of copper in the Alamosa River were increased by the release of acid mine drainage from the Summitville Mine site. Concern about the potential impact to resident waterfowl led to an investigation of copper toxicity in juvenile mallards. The investigation described in this thesis included a small field survey and six laboratory studies. The field survey provided an indication of potential exposure concentrations and a relative measurement of copper exposures in mallards from the Alamosa River. The laboratory studies examined the biological and physiological effects of excess copper in juvenile mallards and the relationship between copper exposure and tissue copper accumulation. Acute copper toxicity produced mortality in juvenile mallards that received a drinking water dose of 800 milligrams of copper per kilogram body weight per day (mg Cu/kg BW/d). Sublethal copper toxicity was quantified by decreased weight gain. Mallards experienced minor reductions in weight gain (10-20%) with exposures ranging from 70-210 mg Cu/kg BW/d. Weight gain was substantially decreased, by more than 50% compared with control birds, in mallards that received larger doses of copper(≥250 mg Cu/kg BW/d). Based on decreased weight gain, a dose of 20 mg Cu/kg BW/d was determined to be a No Observed Adverse Effect Level (NOAEL) for copper in juvenile mallards. Tissue copper concentrations were measured by flame atomic absorption spectrophotometry. Untreated mallards accumulated substantial concentrations of copper in their livers, up to 700 μg Cu/g on a dry weight basis. Hepatic copper increased significantly in mallards that received a dose greater than or equal to 160 mg Cu/kg BW/d. Feather copper concentrations were significantly correlated with both dietary (R2 = 0.99, p < 0.001) and drinking water exposure (R2 = 0.76, p < 0.001). Analysis of feather tissue was determined ...