Associate professor at the University of Wisconsin Center for Limnology Hilary Dugan shared research Tuesday on the effect of changing winters and climate change on lake ecology at Overture Center for the Arts.
All seasons and regions of Wisconsin are becoming warmer and wetter, with winters warming more rapidly than summers, according to the Wisconsin Initiative on Climate Change Impact.
Yet, there is a lack of scientific observations about winter influences on lake dynamics, Dugan said. Generally, lake temperatures are measured by buoys, but since they are powered by solar panels, the snow and ice restrict winter research attempts, Dugan said.
But ice cover is shrinking — according to recent research on Lake Mendota and Monona, the duration of lake ice is declining in Madison by almost a month, Dugan said.
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Winter ice and snow cover result in several important processes in lakes, including a reduction in lake mixing due to wind and a reduction in the exchange of gasses, like oxygen and carbon dioxide, Dugan said.
“Snow is really important in driving how lakes operate in the winter,” Dugan said. “Because of the amount of light and heat that gets through.”
To investigate the effect of snow cover on ice, Dugan’s research team continually compared a plowed lake to an unplowed, snow covered lake. They found the lake without snow had thicker and clearer ice, allowing more solar light to penetrate through the ice and support more algae and zooplankton life, Dugan said.
During the winter, fish decrease their activity, metabolism and food consumption, Dugan said.
But they still move and reproduce — some species have even adapted to the cold and become more active, unlike most fish, Dugan said. Winter is ideal for fish reproduction because the ice protects the eggs and the cold increases egg quality, Dugan said.
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Not only is the duration of winter and ice shorter, but also increasingly unpredictable. This changing pattern has prompted her research on how animals interact in a lake using seasonal cues, Dugan said.
Seasonal changes disrupt lake food chains as well. When ice recedes early and there’s not enough algae for the zooplankton to consume, there is a resulting decline in zooplankton — an important food source for the fish, Dugan said.
“Winter isn’t a dormant season because people and organisms are still very busy,” Dugan said.
These unpredictable and disruptive winters will continue to guide Dugan’s research on lake dynamics in Wisconsin and beyond.
