Study examines how climate change impacts contaminants and excess nutrients in the environment
With increasing water temperatures, there will be more blooms of harmful algae like Microcystis, which has led to the deaths of hundreds of waterbirds, including this green-winged teal photographed at Poplar Island in Chesapeake Bay.
With more intense storms and flooding, there will be greater runoff and erosion, increasing the influx of sediment-bound contaminants such as polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs) into water bodies.
These are just some of the ways climate change may affect the release, dispersal, and negative impacts of toxic chemicals and excess nutrients in the environment, according to a new study on the interactive effects of climate change with nutrients, mercury, and freshwater acidification funded by the North Atlantic Landscape Conservation Cooperative (LCC).
In the Northeast, where some climate change predictions are worse than global averages, the level of threat posed by these interacting environmental stessors is uncertain.
The North Atlantic LCC brought together a team of scientists to investigate this growing threat to natural resources. By combining the known impacts from contaminants and nutrients with documented and predicted changes in climate, the scientists identify imminent risks and research needs in the Northeast region.
"We felt we were missing something important," said lead author Fred Pinkney, a Senior Biologist in the Environmental Contaminants Program at the U.S. Fish and Wildlife Service Chesapeake Bay Field Office, explaining that the study was motivated by an international workshop on climate change and contaminants held by the Society of Chemical and Environmental Toxicology held in 2011.
"We took the concepts that came out of the international workshop, and focused on how they apply to one part of the country, just like climate models are scaled down to certain regions," said Pinkney.
"Now we are one of the first Landscape Conservation Cooperatives to bring contaminants into the picture."
Key Findings
The scientists used a case study approach to focus on regionally relevant environmental stressors and taxa:
- Mercury - Several threatened bird species —including common loon, salt marsh sparrow, and rusty blackbird—are showing high levels of mercury in their blood, which has been linked to lowered nesting success.
- Freshwater acidification - Forests, ponds and lakes in the Adirondacks that have been slowly recovering from acid rain over the past decade are once again showing signs of acidification.
- Eutrophication - Increasing runoff may funnel excess nutrients into estuaries and reduce the amount of dissolved oxygen in coastal waters, causing “dead zones” for marine life. Higher water temperatures also promote harmful algal blooms (HABs), which have caused die offs of birds in the Chesapeake Bay.
- Amphibians - Certain toxic chemicals can lower amphibians' ability to tolerate dry conditions, making them more vulnerable to higher temperatures and increasing frequency of droughts.
- Freshwater mussels - Changing stream temperatures and increasing sediment from runoff may be impacting freshwater mussels, which are sensitive to a form of ammonia that becomes more toxic at higher temperatures.
Next Steps
The scientists will continue to work with the North Atlantic LCC and other partners and partnerships in the Northeast to address climate-contaminant and climate-nutrient interactions. As a first step, they are forming a Mercury Team to take a critical look at the research needs they identified, and propose projects that are feasible and consistent with the goals of the LCC.
Read the full abstract.
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