Behavioral, Clinical, and Pathological Characterization of Acid Metalliferous Water Toxicity in Mallards

Abstract

From September to November 2000, United States Fish and Wildlife Service biologists investigated incidents involving 221 bird deaths at 3 mine sites located in New Mexico and Arizona. These bird deaths primarily involved passerine and waterfowl species and were assumed to be linked to consumption of acid metalliferous water (AMW). Because all of the carcasses were found in or near pregnant leach solution ponds, tailings ponds, and associated lakes or storm water retention basins, an acute-toxicity study was undertaken using a synthetic AMW (SAMW) formulation based on the contaminant profile of a representative pond believed to be responsible for avian mortalities. An acute oral-toxicity trial was performed with a mixed-sex group of mallards (Anas platyrhynchos). After a 24-h pretreatment food and water fast, gorge drinking was evident in both SAMW treatment and control groups, with water consumption rates greatest during the initial drinking periods. Seven of nine treated mallards were killed in extremis within 12 h after the initiation of dose. Total lethal doses of SAMW ranged from 69.8 to 270.1 mL/kg (mean ± SE 127.9 ± 27.1). Lethal doses of SAMW were consumed in as few as 20 to 40 min after first exposure. Clinical signs of SAMW toxicity included increased serum uric acid, aspartate aminotransferase, creatine kinase, potassium, and P levels. PCV values of SAMW-treated birds were also increased compared with control mallards. Histopathological lesions were observed in the esophagus, proventriculus, ventriculus, and duodenum of SAMW-treated mallards, with the most distinctive being erosion and ulceration of the kaolin of the ventriculus, ventricular hemorrhage and/or congestion, and duodenal hemorrhage. Clinical, pathological, and tissue-residue results from this study are consistent with literature documenting acute metal toxicosis, especially copper (Cu), in avian species and provide useful diagnostic profiles for AMW toxicity or mortality events. Blood and kidney Cu concentrations were 23- and 6-fold greater, respectively, in SAMW mortalities compared with controls, whereas Cu concentrations in liver were not nearly as increased, suggesting that blood and kidney concentrations may be more useful than liver concentrations for diagnosing Cu toxicosis in wild birds. Based on these findings and other reports of AMW toxicity events in wild birds, we conclude that AMW bodies pose a significant hazard to wildlife that come in contact with them.

Heavy metal concentrations in Canada geese, snow geese, mallards, and American coots from the northern Rocky Mountains in Montana

“…Assessing acute impacts of AMW can be particularly challenging as a result of metal constituent complexity, synergistic interactions, cumulative effects associated with species-specific behavior and physiology (Isanhart et al 2011), as well as other unknown variables. For example, Hui et al (1998) examined snow geese in central California and suggested that this species may be affected by up to 19 different metals and metalloids that can have cumulative adverse impacts on reproduction and survival.…”

“…Today, the Puls (1994) data pose limitations associated with analysis sensitivity, cross-species comparisons, and the difference between hypothesized normal and exposed levels. In response to the need for better metal concentration comparisons, METAL LEVELS IN NORTHERN ROCKY MOUNTAIN WATERBIRDS | 3 of 14 Isanhart et al (2011) conducted an acute oral-toxicity trial with a mixed-sex group of mallards (Anas platyrhynchos) to build upon previous work associated with metal exposure in waterbirds, specifically evaluating effects associated with consumption of acid metalliferous water (AMW). The results of Isanhart et al (2011) provided a quantitative assessment of dose-response to a suite of metals and associated chemistry values, histopathological changes, and overall survival rates.…”

“…In response to the need for better metal concentration comparisons, METAL LEVELS IN NORTHERN ROCKY MOUNTAIN WATERBIRDS | 3 of 14 Isanhart et al (2011) conducted an acute oral-toxicity trial with a mixed-sex group of mallards (Anas platyrhynchos) to build upon previous work associated with metal exposure in waterbirds, specifically evaluating effects associated with consumption of acid metalliferous water (AMW). The results of Isanhart et al (2011) provided a quantitative assessment of dose-response to a suite of metals and associated chemistry values, histopathological changes, and overall survival rates. While previous research has provided a broad-scale understanding of metal exposure in waterbirds, finescale spatial and temporal data are necessary for assessing normal metal concentrations and those measured in individuals that may be impacted from the Pit or other mining operations in the northern Rocky Mountains.…”

“…Despite a Waterfowl Protection Plan, periodic small-scale mortalities (<1% per year of the total number of waterbirds observed on the Pit) suggest there is still potential risk of acute effects to waterbird species that visit the Pit, even at limited temporal scales. As suggested by Isanhart et al (2011), there are numerous mining operations across the globe that have the potential to cause similar issues with the same or taxonomically similar waterbird species as those associated with the Pit. Establishing environmental baselines is critical for developing effective management strategies and preparing for future anthropogenic events at the Pit as well as other areas exposed to mining activities, particularly in the same flyways.…”

Water requirements and drinking rates of homing pigeons: A consideration for exposure risk of migratory birds

“…The gorge drinking behavior exhibited within the first 30 minutes of arrival is critical when considering a time frame of exposure. Isanhart et al () found that mallards consuming high rates of water after fasting ingested a lethal dose of synthetic acid metalliferous water in just 20 to 40 minutes after 1st exposure. Henny et al () made observations of wild ducks in Nevada landing on and drinking immediately from mill tailings ponds containing cyanide, detailing that the duck that appeared to have drunk the most died within 30 minutes of landing.…”