New Scientific Report Documents the Impacts of Mercury Pollution on Adirondack Loons


An extensive study of New York’s Adirondack loon population has revealed that mercury contamination can lead to population declines of the iconic bird. The research effort was a joint project between the New York State Energy Research and Development Authority (NYSERDA), Biodiversity Research Institute (BRI) and the Wildlife Conservation Society (WCS).

For nearly 10 years, researchers from these organizations followed mercury contamination throughout the aquatic food chain, from zooplankton to the Common Loon, in Cranberry and Lows lakes as well as in other bodies of water.  They found that loons with elevated mercury levels produced significantly fewer chicks than those with low mercury levels, particularly those breeding on the more acidic lakes that are common in the Adirondack Park.

The newly released report, Long-term Monitoring and Assessment of Mercury Based on Integrated Sampling Efforts Using the Common Loon, Prey Fish, Water, and Sediment, highlights scientific findings from 1998 to 2007 that spanned the Adirondack region of New York State.

“NYSERDA is pleased to partner with such esteemed organizations as BRI and WCS to produce a report that will provide researchers and others with a better understanding of the effects of harmful pollutants like mercury,” said Francis J. Murray Jr., President and CEO of NYSERDA. “This study shows the importance of our continued efforts to decrease our reliance on fossil fuels in favor of investment in renewable energy and energy efficiency projects around the state.”

Although naturally present at low levels, mercury becomes an air pollutant largely through emissions from coal-fired power plants. In some areas, cement plants and mining-related industries also contribute to mercury pollution. Airborne mercury eventually returns to the earth in rain, snow and fog droplets, as well as in dry form.

Winds carry the pollutant from distant point sources. Adirondack lakes—where aquatic loons live and raise young—are exposed to mercury contamination deposited in the environment. Mercury is toxic at even small levels, and accumulates in animals as it progresses up the food chain. Loons feed at the highest level in the food web, which increases their risk of the toxic effects of mercury exposure.

Scientists found that mercury was present in loons at a level that put the birds at risk of reproductive harm—21 percent of male loons studied and 8 percent of females were at a high risk of behavioral and reproductive impacts based on the levels of mercury in their bodies.

Adult loons with high mercury levels also lack good parenting skills, for example, these birds do not incubate eggs consistently enough for chicks to hatch. Thus, the high mercury birds experienced lower reproductive success than the low mercury birds because of the reduced hatching rate of the eggs.

“From this study we know that more than half of the adult Adirondack loons are at moderate to high risk of mercury poisoning,” says Zoë Smith, director of WCS’s Adirondack Program. “The long-term survival of loons in the Park will depend on reducing mercury in the atmosphere.”

The New York State Department of Environmental Conservation also provided support for the study.

“DEC is pleased to have partnered with these organizations on this important long-term study of the impact of mercury on common loons,” said DEC Commissioner Joe Martens. “Since 1998, DEC has provided staff and resources to ensure the success of this project. Our work together has resulted in a better understanding of the biology of this state-listed special concern species and provides valuable insight for future management.”

In December of 2011, the U.S. Environmental Protection Agency (EPA) finalized the Mercury and Air Toxics Standards Rule that requires coal-fired power plants to update their mercury pollution control technologies. However, overseas emissions are also a problem. BRI scientists have been involved in helping to inform mercury emissions policy on both domestic and international levels.

“The good news is that efforts to control mercury pollution here in the United States have been very beneficial, as we have discovered in our extensive mercury studies throughout the Northeast and in the Great Lakes region,” says David C. Evers, Ph.D., executive director and chief scientist of BRI. “One of BRI’s core missions is to support the policymaking process with good science. Our findings in this loon study demonstrate the need for the EPA’s ruling and highlight the importance of mercury tracking through better national and international monitoring programs.”

Dr. Evers, as a member of the UN’s Environment Programme, is actively involved in the development of a global treaty on mercury monitoring, which is expected to be ratified in 2013. “We are learning a great deal from our work in the U.S., and we have an opportunity to expand our knowledge on an international scale to help ensure that effective policies are put into place and are appropriately monitored over time.”

This long-term research was conducted with financial and in-kind support from NYSERDA, Wildlife Conservation Society, The Wild Center, the New York State Department of Environmental Conservation, and Audubon International. Additional financial and in-kind support was provided by the Freed Foundation, Nordlys Foundation, John and Evelyn Trevor Charitable Foundation, SUNY ESF’s Adirondack Ecological Center, Paul Smith’s College Watershed Stewardship Program, and numerous other organizations and private donors.

To view a copy of the study and other information, click here .

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