Twin Ports Freshwater Folk: Impacts of Changing Winters on Lake Ecosystems will Increase with Latitude

You’re invited to a hybrid Twin Ports Freshwater Folk event on April. 3, 2024, at 11:30 a.m. with free sub-sandwiches and freshwater, followed by a seminar by Ted Ozersky. The in-person side of the event will take place at the Minnesota Pollution Control Agency office in Duluth. A zoom option is also available. This event is free and open to the public. 


Ted Ozersky is an Associate Professor of Biological Limnology at the Large Lakes Observatory and Biology Department at UMD. He is interested in lake biogeochemistry, benthic and plankton communities, and food webs, with an emphasis on the ice cover period of small and large lakes.

Presentation Abstract

Climate warming is especially pronounced in winter and at high latitudes. Warming winters are leading to loss of lake ice and changing snow cover on seasonally freezing lakes. Past neglect of the ice cover period by lake scientists has resulted in critical data and theory gaps about the role of winter conditions in lake ecosystem function and the effects of changing winters on aquatic systems. Here we use simple models to show that the latitudinal interaction between ice cover duration and light flux seasonality has profound and underappreciated implications for lake ecosystems. Our models focus on light and temperature, two paramount drivers of ecosystem processes. We show that the amount of light arriving in lakes while they are ice-covered increases non-linearly with latitude and that light climate of high-latitude lakes is much more sensitive to changing winter conditions than that of lower-latitude lakes. We also demonstrate that the synchronicity between light flux (a key controller of primary production) and temperature (which controls invertebrate production) decreases with latitude. Our results indicate that ice loss will lead to greater change to the productivity and nature of biotic interactions in higher latitude aquatic ecosystems and make several testable predictions for understanding the consequences of climate-induced changes across latitudinal gradients.


Wednesday, April 3, 2024


11:30 a.m. - 1:00 p.m. CT


  • In-person registration
  • Location: Minnesota Pollution Control Agency, located in the Paulucci Building, 525 S. Lake Ave. # 400A, Duluth, MN 55802.
  • Directions: Take the elevator to the 4th floor. The conference room is a right turn from the elevator.
  • Public parking in Canal park is free. Commercial lots are not free.
  • Lunch will be provided.


  • Virtual registration
  • The virtual portion of the meeting will start at 12:00 p.m. CT. Note that there will be no virtual meet-and-greet breakout session.

Event schedule

  • 11:30 a.m. Lunch and networking (in-person only)
  • 12:00 p.m. Announcements by attendees (virtual and in-person)
  • 12:05 p.m. Seminar(s) (virtual and in-person)
  • 12:45 p.m. Moderated question and answer (virtual and in-person)
  • 1:00 p.m. Adjourn

About TPFF

Twin Ports Freshwater Folk (TPFF) is an informal gathering of people from the Twin Ports of Duluth, Minnesota and Superior, Wisconsin, who are engaged in freshwater research, policy, or regulation issues, for networking and informal discussion. Meetings take place the first Wednesday of every month.

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Alex Frie, research and fellowship coordinator, Minnesota Sea Grant, University of Minnesota and University of Minnesota Duluth.

Ted Ozersky holds an ice auger. Image courtesy of: Ted Ozersky.