By Alia Benedict, MW CASC Graduate Fellow 

November 14, 2024

Winter is a biologically active period in lakes. If anyone knows this, it’s ice fishers, who have long understood that life is active under lake ice. Winter lake scientists (or winter limnologists) are beginning to learn this too.  For example, we know that ice and snow are ‘master variables’ that control the degree of biological activity in winter. We know that lower trophic levels and fish are active under ice, and that they play an important role in full-year nutrient processing and energy flow.

However, we don’t know a lot about how fish survive winter. We know that winter can be a key bottleneck for fish survival and recruitment, and that life history traits can influence how fish survive (or thrive) under the ice. Warm-water species such as panfish become more dormant in winter, while cool-water species such as perch and walleye rely on cold temperatures to reproduce. These differences may impact how game fish feed, grow, and survive the winter period, and further, how they may adapt to changing winters. However, the lack of information about the winter biology of game fish limits our understanding of full-year lake ecosystem function, as well as our ability to make lake management decisions.

The Ozersky Lab at the University of Minnesota-Duluth studies how changing winters affect the biology of lake ecosystems. With the support of the Midwest Climate Adaptation Science Center (MW CASC) and the Environment and Natural Resources Trust Fund (ENRTF), my job is to identify how seasonal changes in abiotic parameters (such as light, oxygen, temperature, and nutrients) and biotic communities (such as phytoplankton, zooplankton, and benthic invertebrates) shape the seasonal diets of freshwater game fish in lakes that differ in trophic status and winter duration. This information, which can be used by winter limnologists, lake managers, and lake users, can ultimately help predict how game fish will respond to changing winters.

The more time I spend on the ice, the more I see how much people care about winter. In fact, much of the data that winter limnologists use, such as lake ice trends and snowfall rates, are based on community observation. I joined the MW CASC because it provides opportunities for scientists and managers to produce research that is useful to science and society. Working together to increase the quality, quantity, and scope of winter data will become more important as changing winters continue to affect our freshwater resources. 

Alia Benedict (she/her) is pursuing a doctorate in the Water Resources Science Program at the University of Minnesota-Duluth. Her research focuses on how changing winters will affect lower trophic levels and fish in north temperate lakes.