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  • Ecology and Evolutionary Biology
  • Climate Change

Lakes are among the most vital natural resources on Earth. While they hold a small percentage of the planet’s overall water supply, they provide most of the fresh water people depend on daily. A new five-year, $2.5 million grant from the National Science Foundation will examine how rapidly warming temperatures and shorter winters can influence the growth and toxicity of lake algae.

The grant is led by Rebecca North of the University of Missouri. Meredith Holgerson, assistant professor in the Department of Ecology and Evolutionary Biology, is leading the Cornell research team. Other collaborators are Isabella Oleksy of the University of Colorado at Boulder; Ana Morales of the University of Vermont; and Dave Richardson of the State University of New York at New Paltz.

The researchers will use predictive modeling to make water quality projections, specifically about levels of phytoplankton and the cyanobacteria that cause harmful algal blooms, and about potential increases or decreases in toxin concentrations. They will study how year-round algal growth and increasingly warmer winter temperatures could negatively affect lake ecosystems and water quality.

“To do that, we’ll collect data from a whole suite of lakes all the way from alpine lakes in the Rocky Mountains in Colorado and ice-covered lakes up in Vermont and New York state, down to lakes in Missouri and some in Florida,” North said.

Holgerson and her team at Cornell will study how changing ice duration affects algae growth year-round. Using Cornell’s Experimental Ponds, the researchers will manipulate how long ice cover lasts on the ponds and examine the effects on algae production. Three ponds will experience an unmanipulated winter ice cover, three will have ice formation delayed by one month and three will be ice-free all winter. Ice manipulations will be done using underwater circulators that can keep the pond surface free of ice.

woman drilling into a frozen lake
Meredith Theus, a graduate student in Meredith Holgerson's lab, collects sediment from a frozen pond at Cornell’s Experimental Pond Facility. The pond facility will be used to manipulate ice cover and monitor changes in phytoplankton dynamics. Photo credit: Nicholas Ray, a postdoctoral associate in Holgerson's lab.

“Ice duration informs numerous ecological and biogeochemical parameters in lakes and ponds,” Holgerson said. “We expect that water bodies will have an ‘ecological memory,’ meaning that what happens in the winter will have carry-over effects to the following spring and summer. For instance, lakes or ponds with less ice or no ice may have earlier algal growth in the spring and alter competition outcomes among different algal taxa.”

Holgerson sees the research as important to mitigating the effects of climate change.

“We don’t have a great handle on what conditions promote cyanobacteria, under what conditions they produce toxins, and how cyanobacteria compete with other phytoplankton that don’t produce toxins and are important for food webs,” she said. “As we expect more algal blooms in the future, understanding drivers will be important for mitigation.”

North said the work will establish baseline measurements, key to understanding those drivers.

“One of the problems of making predictions about what's going to happen in the future when we have shorter winters is that we don’t have any baseline conditions for comparison,” North said. “This is because few people sample lake water in the winter; it’s logistically challenging to get out on the ice with snowmobiles when the lake surfaces are less frozen. Taking measurements in the winter will help us understand the legacy effect of what occurs the following summer if it’s preceded by a shorter, milder winter.”

A version of this story was originally published by the University of Missouri.

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