National Park

Study of algae in Acadia National Park lakes shows recovery after acidification – UMaine News

Acadia National Park is known for its beautiful lakes – and they can tell scientists a lot about the health of the environment. New research shows that regulations to reduce anthropogenic sulfur in the atmosphere have made a difference for lakes in Acadia National Park, though climate change may slow that recovery.

Research in the 1990s showed that human-caused air pollution in the 20th century caused lakes in eastern North America to acidify beginning in the 1940s. decrease in dissolved organic carbon in lakes, which impacts lake ecology and makes water clearer.

Since amendments to the Clean Air Act were enacted at the federal level in 1990, the Northeastern United States has received significantly less atmospheric acid deposition in an effort to restore ecosystems like lakes that were impacted by the pollution. However, climate change can also impact lake water clarity, as rising temperatures lead to the production and release of dissolved organic carbon, while changes in precipitation caused by climate change can also add more organic matter.

Researchers from the University of Maine and the National Park Service wanted to see how these changing dynamics of acidification affected the ecosystems of different types of lakes in Maine. In one article published in the Journal of Paleolimnology, scientists have pieced together historic pigment records of algae and diatoms – a special type of algae with a silica shell, which is generally negatively affected by acidification – from two lakes in the park Acadia National, Jordan Pond and Seal Cove Pond.

Despite their geographical proximity, the two lakes are very different. Jordan Pond is considered a “clear water” or oligotrophic lake, meaning its waters are relatively poor in plant nutrients with an abundance of oxygen at its depths. Seal Cove Pond is a “brown water” or mesotrophic lake with a moderate amount of nutrients.

“Recovery from acidification depends in part on water clarity, which is affected by climate change. Across North America and Northern and Central Europe, there is a continuing trend of “browning” lakes. Several studies have described ecological changes in clear water lakes compared to brown water lakes in response to reduced acid deposition and browning, and our paleolimnological study provides long-term context for interpreting these changes,” explains Rachel Fowler, coordinator of the biology lab who served as the project’s principal investigator for her doctorate. at the University of Maine’s Climate Change Institute.

The researchers took sediment cores from the deepest parts of the two basins and analyzed the concentrations of different types of algae and their variation over time. The results showed that algae in the lakes reacted differently over time to acidification. Despite their differences, the two ecosystems are recovering since environmental regulations reduced the amount of atmospheric sulfur in the region, with many types of algae returning to where they had been expelled by acidification.

“An interesting finding is that this study illustrates the effectiveness of the Clean Air Act amendments. We can see signs of acid deposition recovery using the algal remains preserved in the sediments of Jordan Pond and Seal Cove Pond,” says Fowler.

However, the results also suggest that clear-water lakes like Jordan Pond are more sensitive to global warming than brown-water lakes like Seal Cove Pond. Recovery of the algal ecosystem has been slower for Jordan Pond and may continue to be hampered by the effects of climate change.

“Lake color and clarity are major regulators of lake ecology. They can alter the physical and chemical structure of lakes and also contribute to the types and amount of algae living in lakes. With the trend toward browning lakes due to climate change and other environmental factors, it is critical that we understand the ecological consequences for the lakes we value for drinking water, recreation, and natural beauty all the time. year,” says Fowler.

Fowler conducted the research with Jasmine Saros, associate director of the Climate Change Institute and professor in the School of Biology and Ecology; Kate Warner, Ph.D. in Ecology and Environmental Science; and Bill Gawley, biologist at Acadia National Park. The research was funded in part by a Second Century Stewardship award from the Schoodic Institute of Acadia National Park.

Contact: Sam Schipani, [email protected]