Date of this Version
Waste generated by concentrated animal feeding operations (CAFOs) may contain a variety of contaminants including nutrients, pathogens, trace elements, antibiotics, and hormones. In 2000, the U.S. Fish and Wildlife Service began to characterize CAFO contaminants in lagoons, canals, and created wetlands operated by Hastings Pork, a large swine CAFO adjacent to McMurtrey National Wildlife Refuge (McMurtrey) in Clay County, Nebraska. The created wetlands were designed to attract waterfowl; therefore, the primary purpose of this research was to evaluate whether migratory waterfowl were likely exposed to CAFO contaminants. A secondary research objective was to determine if created wetland water was suitable as a supplementary water source for McMurtrey. Wetlands created from swine wastewater effluent had 5-50 fold greater concentrations of phosphorus, ammonia, and total nitrogen and 2-3 fold greater salinity compared to control sites. Cyanobacteria (Microcystis spp.) were abundant in the created wetlands and microcystin toxins were detected in concentrated water samples. Tetracycline, macrolide, and diterpene antibiotics were detected in lagoon and canal sediment and water samples; however, in the created wetlands only oxytetracycline was detected (once in sediment at 41 nanograms per gram). Concentrations of 17-β estradiol and testosterone in CAFO wastewater (n=4) exceeded toxicity thresholds for aquatic life. Fecal coliform and streptococci counts in water (n=38) generally exhibited a decreasing gradient with lagoons > canals > created wetlands > McMurtrey. Bacteria (Salmonella spp. and Yersinia enterocolitica) were recovered in the created wetlands but not McMurtrey. Created wetland invertebrate communities were dominated by chironomid species and had lower taxa diversity when compared to McMurtrey. Eutrophication of created wetlands may represent the greatest health threat to waterfowl by creating an environment conducive to cyanobacteria blooms and outbreaks of avian botulism and avian cholera. Trace elements from swine waste will likely continue to accumulate in the created wetlands over time, leading to an increased risk of exposure to wetland biota. Research is ongoing and includes use of sentinel mallards (Anas platyrhynchos) to further evaluate the need to decrease concentrations of CAFO contaminants in swine wastewater before it is used to create waterfowl habitat.