New report highlights mercury pollution impacts on ecosystems

Earlier this week, the Ecological Society of America, in partnership with the Biodiversity Research Institute (BRI), the Great Lakes Commission and the Northeast-Midwest Institute, cosponsored a Congressional briefing entitled: “Mercury and Air Pollution Impacts on Ecosystems: Policy-Relevant Highlights from New Scientific Studies.”

The briefing sought to highlight the findings of a recent report from BRI highlighting mercury pollution in the Great Lakes region. The featured speakers included Charles Driscoll, a National Academy member and professor at Syracuse University and David Evers, Executive Director and Chief Scientist at BRI.  Congressman Dennis Kucinich (D-OH) kicked off the briefing with some opening remarks noting the detrimental health effects mercury pollution can have on families in the Great Lakes region.

According to the report, emissions of mercury to the air (and subsequent deposition) are now the primary source of mercury pollution to the Great Lakes region. Twenty-six percent of mercury deposition in Canada and the continental United States is from the Great Lakes region, with the highest concentrations in Ohio, Indiana and Wisconsin.

The presence of methylmercury (inorganic mercury that has been altered by bacteria in the natural environment) affects the entire food-chain of an ecosystem. Plants take up the toxin and are subsequently fed upon by plant-eating insects and fish, which in turn are consumed by insectivores and fish-eating animals, including songbirds, waterfowl and humans.

A number of bird species were found to have “high sensitivity” to mercury pollution, including the American Kestrel, the American White Ibis, the Snowy Egret, the Osprey and the Tri-Colored Heron.  The study notes that the U.S.  national bird, the Bald Eagle, is also negatively impacted by mercury, with effects that  include “subclinical neurological damage.” The Bald Eagle was removed from being listed as “threatened” under the Endangered Species Act in 2007. It was declared a federally endangered species from 1967-1995.

The speakers noted that fish polluted with mercury can have detrimental impacts on the local economy and human health. “In recent years, we’ve come to appreciate that pollution from mercury and acid rain affects wildlife health as well as human health,” said Evers.

Among 15 fish species in the region consumed by people and wildlife, six species have average mercury concentrations above 0.30 parts per million. The report notes that five states in the region “have issued statewide consumption advisories for mercury in fish from all fresh waters, two have issued statewide advisories for mercury in fish from all lakes, and one has issued advisories for specific water bodies.”

According to the BRI study, “sport fishing in the eight Great Lakes states supports more than 190,000 jobs and annually has a total economic impact of more than $20 billion.” It states that women of child-bearing age who consume contaminated fish are of greatest concern, noting that “an estimated 300,000 to 400,000 children born each year are exposed to methylmercury in utero at levels high enough to cause neurological health impairment.”

Briefing speakers maintained that declines in mercury pollution parallels increased regulatory efforts to curb air emissions from regional and U.S. sources.  According to the BRI study, “Given that recent declines in sediment mercury levels have been observed in a large number of lakes sampled by several investigators, these observations suggest a cause and effect relationship between controls on local and regional emissions of mercury to the atmosphere and partial ecosystem recovery from mercury contamination.”

The study also notes that the more research investment we commit to studying mercury, the more we realize about how far-reaching its impacts are. For example, elevated mercury levels have been documented in a growing number of bird species and habitats that now include floodplain forests, bogs and marshes.

The Environmental Protection Agency (EPA) provides a detailed webpage outlining its current efforts to monitor mercury pollution and limit harmful power plant emissions. EPA states that “currently, there are no national limits on the amount of mercury and other toxic air pollution released from power plant smokestacks.” The agency maintains that reducing power plant emissions of mercury pollution will significantly benefit human health, preventing thousands of premature deaths, heart attacks, bronchitis cases and asthma attacks. It estimates that the health improvements will eventually save $59 billion to $140 billion, getting “$5 to $13 in health benefits” for every dollar spent to reduce power plant pollution.

The briefing also highlighted ESA’s most recent Issues in Ecology, entitled “Setting Limits: Using Air Pollution Thresholds to Protect and Restore U.S. Ecosystems.” The report  offers strategies to curb various pollutants emitted from power plants and industry, including toxic mercury. View the full report here.

The briefing’s speakers noted that a lack of basic knowledge still exists with regard to mercury pollution’s impacts on ecosystems and human health, highlighting the need for comprehensive improved mercury monitoring.