Mercury and Air Toxics Standards (MATS) Part III: Ecology

According to the Hidden Risk Report, a publication from the Biodiversity Research Institute in partnership with The Nature Conservancy, “invertivores” are greatly affected by mercury emissions from coal-fired power plants.  Songbirds and bats are referred to as invertivores because they eat a variety of invertebrate species like spiders, snails and worms; not just insects.  Invertivores are an integral part of healthy ecosystems, functioning as seed dispersers and insect controllers.  Mercury emissions are threatening their chances for survival and therefore the health of ecosystems throughout the nation.  There are large declines in reproductive success and developmental issues in some species.  For example, Common Loons have to spend roughly 98% of their time on their nest incubating eggs in order for the eggs to successfully hatch.  After over 5,000 hours of observation, it has been determined that Loons with high mercury levels spend only 85% of their time incubating eggs.  The eggs do not hatch and the species reproductive success decreases (Evers, et al.).

Early research on mercury and wildlife focused primarily on fish-eating birds and mammals, but now it is clear that mercury affects a wider range of species at varying trophic levels.  A simple food chain: a spider eats a fly, and a bird like a Northern Water Thrush or sparrow eats the spider, the song bird will have more mercury in its blood than a Bald Eagle.  While blood samples are taken from humans to determine mercury exposure, feather samples are taken from birds.  The average level of mercury for all sampled individuals was 20 ppm, while the maximum level detected was 40 ppm.  Mercury exposure is dependent on species characteristics, like trophic level, and habitat.  Wetlands, especially estuaries, bogs and beaver ponds, allow for a high rate of methylation, producing high mercury levels in organisms that live there (Evers, et al.).

While wetlands are mostly threatened by mercury pollution, point-source mercury has been shown to persist in rivers more than 80 miles from its original source.  This makes mercury a danger to species far beyond wetland areas.  Methylmercury has been connected with organic soil and leaf litter, so even forest species are at risk of exposure.  Songbirds that feed primarily on forest floor by moving around leaf are affected, as are the invertebrates on the forest floor (Evers, et al.).

Mercury exposure also causes physiological rarities in songbirds, impacting their migration patterns.  If a bird’s left wing is five percent different in shape than its right wing, the bird has to fly in an odd way to compensate for the difference.  This requires more energy and affects survival rates of song bird species when migration already accounts for 75% of all annual mortality rates in some songbirds.  Mercury exposure becomes an added burden on the species (Evers, et al.).

Saltmarsh Sparrow

Many invertivores are already at risk because of pollution, loss of habitat and invasive species.  In combination with environmental stressors like acid rain and climate change, wildlife species are suffering from a synergistic reaction of all of these threats acting together.  Mercury exposure adds another “ecological burden” on songbird and bat populations.  Bats with high levels of mercury often experience compromised immune systems, making it difficult to fight infections like White-Nose Syndrome.  The saltmarsh sparrow has a “very high mercury risk,” according to The Hidden Report, because it is endemic to estuaries, spends its entire life cycle in saltmarsh habitats, and eats high in the food chain.  The saltmarsh sparrow is also especially vulnerable to sea level rise as a result of climate changes, piling one “ecological burden” on top of another (Evers, et al.).

Standardized monitoring of invertivores is needed to show how the new MATS affect changes in mercury emissions because these species offer valuable ecosystems services.  A single colony of big brown bats eats nearly 1.3 million pest insects each year. Pest suppression services provided by native bats in US agricultural landscapes is valued at $22.9 billion per year.  A bluebird family of two parents and five nestlings requires 124 g of insects per day.  The presence of nesting birds in vineyards reduces the amount of pesticides that are required to maintain healthy crops (Evers, et al.).

While standardized monitoring of wildlife, laws and regulations like Mercury and Air Toxics Standards (MATS), and scientific health studies help to address some environmental problems, other means could be used.  Social media has played a large role in the environmental movement in 2012.  Facebook and Twitter has helped to spread the word about fracking throughout the United States and the development of the Keystone XL tar sands pipeline in the Great Plains.  Greenpeace used Facebook as part of their clean energy campaign.  The organization urged citizens to “defriend coal.”  The Unfriend Coal campaign showed Facebook’s new data centers that draw energy from coal-powered plants.  After this blitz, Facebook announced that finding renewable energy sources would a priority in future data centers and agreed to lobby utilities powering their existing centers to increase their reliance renewable energy.  Facebook also allows organizations to expand their membership into new countries (Kaufman).

Mercury and Air Toxics Standards are similar to other environmental policies in many ways.  There has been criticism from economists, claiming that MATS will contribute to unemployment and negatively affect the economy of the United States.  MATS will be subjected to gutting by conservation politicians and vague language and claims protecting the privileged few.  The risk of mercury emissions to wildlife, such as invertivores like bats and songbirds, will be examined at length by wildlife conservationists.  New age environmentalists will stay informed and advocate for MATS through social media.  MATS, however, will stand out among other environmental policies because of its clear, scientific connection to public health and the strong lobby of mothers that will fight for their children’s health.


Evers, D.C., A.K. Jackson, T.H. Tear and C.E. Osborne. 2012. Hidden Risk: Mercury in Terrestrial Ecosystems of the Northeast. Biodiversity Research Institute. Gorham, Maine. BRI Report 2012-07. 33 pages.

Kaufman, Leslie. “For Green Groups, a Shift in Tactics.” Green Blog. New York Times, 19 Dec. 2011. Web. 15 May 2012. <;.

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