Mercury pollution is making its way into nearly every habitat in the U.S., exposing countless species of wildlife to potentially harmful levels of mercury, a new report from the National Wildlife Federation shows.
“From songbirds to alligators, turtles to bats, eagles to otters, mercury is accumulating in nearly every corner of the food chain,” says Catherine Bowes, Northeast Program Manager for the National Wildlife Federation and principal author of the report. “This report paints a compelling picture of mercury contamination in the U.S., and many more species are at risk than we previously thought. Fish, long thought to be the key species affected by mercury, are just the tip of the iceberg.”
The National Wildlife Federation report, Poisoning Wildlife: The Reality of Mercury Pollution, is a compilation of over 65 published studies finding elevated levels of mercury in a wide range of wildlife species. The report highlights mercury levels in fish, mammals, birds, reptiles and amphibians living in freshwater, marine, and forest habitats from across the country.
The accumulation of mercury in fish has been well-understood for years, leading 46 states in the U.S. to issue consumption advisories warning people to limit or avoid eating certain species of fish. However, scientists have recently discovered that mercury accumulates in forest soils, indicating that wildlife that live and feed outside aquatic habitats are also at risk of exposure to mercury.
“Scientific understanding of the extent of mercury contamination in wildlife has expanded significantly in recent years,” says Dr. David Evers of the Biodiversity Research Institute, wildlife toxicologist and leading researcher in this field. “We are finding mercury accumulation in far more species, and at much higher levels, than we previously thought was occurring. This poses a very real threat to the health of many wildlife populations, some of which are highly endangered.”
Mercury accumulation in fish is not only a concern for the health of people who eat them, it also poses a threat to the fish themselves. Poisoning Wildlife pulls together the major findings from over 20 of the 65 published studies that attribute adverse health impacts on fish, birds, and mammals with elevated mercury levels in those species. Fish with high mercury levels have difficulty schooling and spawning, birds lay fewer eggs and have trouble caring for their chicks, and mammals have impaired motor skills that affect their ability to hunt and find food.
Several states have already taken action to reduce mercury pollution from major sources like waste incinerators, chlorine manufacturers, power plants, and consumer products, and the results are very promising. In places where mercury emissions have been cut, such as Florida, Wisconsin, New Hampshire, and Massachusetts, mercury levels in fish and wildlife have been reduced in a matter of years, not decades, as scientists have previously thought.
“Now that we have hard evidence that mercury is affecting more species than originally thought, anything short of phasing out this toxic metal is inadequate,” says Bowes. “The discovery of mercury in so many different species is a wake-up call. We need to ensure that all is being done to help wildlife cope with the stresses of a changing climate. Eliminating known threats like mercury is a critical place to start.”
The scientific studies compiled in the report show mercury in a wide variety of species:
- Freshwater Fish: Brook Trout, Walleye, Yellow Perch, Rainbow Trout, Northern Perch, Largemouth Bass
- Birds in Aquatic Habitats: Bald Eagle, Great Egret, Wood Stork, Northern Shoveler, Common Loon, Red-winged Blackbird, White Ibis, Common Tern, Belted Kingfisher
- Birds in Forest Habitats: Wood Thrush, Red-eyed Vireo, Louisiana Waterthrush, Bicknell’s Thrush, Carolina Wren, Prothonotary Warbler
- Mammals: Florida Panther, Indiana Bat, Mink, River Otter, Raccoon
- Reptiles, Amphibians, Invertebrates: Two-lined Salamander, Snapping Turtle, Crayfish, American Alligator, Bullfrog
- Marine Life: Tiger Shark, Sperm Whale, Striped Bass, Loggerhead Sea Turtle, Narwhal, Polar Bear, Beluga Whale, Ringed Seal
More information on mercury and montane songbirds from VINS.