Study of algae in Acadia National Park lakes shows recovery from
acidification

Date:
March 2, 2022
Source:
University of Maine
Summary:
Research shows that federal regulations to reduce human-caused
sulfur in the atmosphere have aided in the recovery of algal
ecosystems for two lakes in Acadia National Park. However,
the study also shows that the warming climate negatively impact
certain types of lakes more than others, which could affect future
ecosystem recovery.



FULL STORY ========================================================================== 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 human-caused sulfur in the atmosphere
have made a difference for lakes in Acadia National Park, though climate
change may slow that recovery.


========================================================================== Research from the 1990s showed that human-caused atmospheric pollution
in the 20th century caused the acidification of lakes across eastern
North America starting in the 1940s. Acidification of lakes causes the
decrease of dissolved organic carbon in lakes, which impacts lake ecology
and makes water appear clearer.

Since the Clean Air Act Amendments were federally enacted in 1990, the northeastern United States has received significantly less atmospheric
acid depositions with the goal of restoring ecosystems like lakes
that were impacted by the pollution. However, climate change can also
impact lake water clarity, as rising temperatures drive the production
and release of dissolved organic carbon, while shifts in precipitation
caused by climate change also can bring in more organic matter.

Researchers from the University of Maine and the National Park Service
wanted to see how these changing acidification dynamics were affecting the ecosystems in different types of lakes in Maine. In an article published
in the Journal of Paleolimnology, scientists reconstructed historical
pigment records of algae and diatoms -- a particular type of algae with
a silica shell, which is usually negatively impacted by acidification --
from two lakes in Acadia National Park, Jordan Pond and Seal Cove Pond.

Despite being close geographically, the two lakes are very
different. Jordan Pond is considered a "clear-water" or oligotrophic lake, meaning its waters are relatively low in plant nutrients with abundant
oxygen at its depths. Seal Cove Pond is a "brown-water" or mesotrophic
lake with a moderate amount of nutrients.

"Recovery from acidification is partially dependent on water clarity,
which is impacted by climate change. Across North America and northern
and central Europe, there is an ongoing trend toward 'brownification'
of lakes. Several studies have described ecological changes in clear-
vs. brown-water lakes in response to reductions in acid deposition and browning, and our paleolimnological study provides long-term context for interpreting those changes," says Rachel Fowler, biology lab coordinator
who served as the principal investigator of the project for her Ph.D. in
the University of Maine Climate Change Institute.

The researchers took sediment cores from the deepest parts of both ponds
and analyzed the concentrations of different types of algae and the way
they varied over time. The results showed the algae in the lakes responded differently over time to acidification. Despite their differences, both ecosystems are recovering since environmental regulations have reduced
the amount of atmospheric sulfur in the area, with many types of algae returning where they had once been pushed out by acidification.

"An exciting takeaway is that this study illustrates the effectiveness
of the Clean Air Act Amendments. We can see signs of recovery from acid deposition using the remains of algae preserved in the sediments of
Jordan Pond and Seal Cove Pond," says Fowler.

However, the results also suggested that clear-water lakes like Jordan
Pond are more sensitive to climate 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 contribute to the
types and amount of algae living in lakes, too. With the trend toward brownification of lakes due to climate change and other environmental
factors, it's essential that we understand the ecological consequences
for the lakes we value for drinking water, recreation and year-round
natural beauty," 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 sciences; and
Bill Gawley, biologist at Acadia National Park. The research was funded
in part by a Second Century Stewardship award from Schoodic Institute
at Acadia National Park.

========================================================================== Story Source: Materials provided by University_of_Maine. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Rachel A. Fowler, Kate A. Warner, William G. Gawley, Jasmine
E. Saros.

Paleolimnological comparison of algal changes in a clear-versus a
brown- water lake over the last two centuries in the northeastern
U.S.A. Journal of Paleolimnology, 2022; 67 (3): 289 DOI:
10.1007/s10933-022-00233-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220302190006.htm

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