Sediment ingestion rates in waterfowl (Anatidae) and their use in environmental risk assessment

When waterfowl (Anatidae) ingest sediment as they feed, they are exposed to the environmental contaminants in those sediments. The rate of ingestion may be key to assessing environmental risk. Rates of sediment ingestion were estimated as from <2% to 22% in 16 species of waterfowl collected in the northeastern United States. The piscivorous red-breasted merganser (Mergus serrator) ingested sediment at the lowest rate and the benthos-feeding canvasback (Aythya valisineria) at the highest rate. Sediment ingestion rates were related to diet and to the sediments where waterfowl fed. Waterfowl ingested the least sediment from hard-bottomed habitats with fast-moving water and ingested the most sediment from soft-bottomed areas with slow-moving water. Understanding the greater hazards from contaminants associated with low-flow habitats may help in prioritizing sites to be remediated. The tundra swan (Cygnus columbianus), which ingests sediment at an estimated 8.4% of its diet, dry weight, is suggested as a potential generic model for use in environmental risk assessments designed to protect waterfowl.