Winter in the Underwater Forest

By Paul Skawinski

Gazing over a frozen lake, it’s hard to imagine a lush forest of green plants, especially under your boots, through the snow, and under a foot or more of solid ice. But believe it – there is a thriving ecosystem down there, even though its residents may be a bit more lethargic than last time you saw them.

While many plants are brown above the ice, it can be nice and green below it.

If you’re looking for greener pastures during some dreary winter weather, go no further than your local lake for some relief.

In an effort to understand what our aquatic plant communities look like beneath the ice, and which species are toughing it out during the long, dark winter, I have been working with a couple of fellow botanists to peer into this mysterious world. Bringing along a bunch of homemade equipment, some specialized camera gear, a lot of warm clothing, and some equally crazy colleagues, I set out to find some answers.

On a few weekends per year since 2012, we have visited fourteen lakes in Central and Northern Wisconsin, marking a few of the sites so that we could repeatedly visit them and watch how they change through the winter season. As of our last adventure on March 1st, 2015, we compiled a list of 30 species that are persisting as apparently healthy, green plants under the ice. We’ve also been delighted to see an abundance of animal life living in these miniature forests, especially caddisflies, large zooplankton like Daphnia and copepods, and fishes such as sculpins, bluegills, and bluntnose minnows. Beds of green plants appear to be serving as gathering places for animals at a time when other areas of the lakes are desolate by comparison. Old Man Winter brings us lakes that appear lifeless and frozen in time, but rest assured they are swimming with life! We have video of all that life that you can check out on the UWEX Lakes Youtube channel.

Fancy seeing you here, sculpin!

Fancy seeing you here, sculpin!

What started out as a one-day trip to a couple of lakes has turned into a Sunday tradition to explore additional lakes and seek out individual plant species. Each spring, we’re always excited to see which of our leafy friends powered through to see the light – the light of springtime, that is.

Paul Skawinski is the Statewide Coordinator of the Citizen Lake Monitoring Network, and teaches Aquatic Plant Biology at UW-Stevens Point. He is also the author of Aquatic Plants of the Upper Midwest.

About timcampbell

AIS communications specialist for UW-Extension and WDNR.
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7 Responses to Winter in the Underwater Forest

  1. Michael Wade says:

    Your article was most interesting and I enjoyed it a great deal. There obviously is an entire paradise and world under the ice … Could someone comment on how invasive water species (Eurasion Water Milfoil, etc.) survive or don’t survive in this under the ice water paradise … Thank you …

    • timcampbell says:

      Hi Michael – thanks for the comment! Here is a reply directly from Paul: Eurasian watermilfoil and curly-leaf pondweed have both been seen persisting under the Wisconsin ice as part of this project. Both of these species can tolerate low light levels, so they are well adapted to surviving under ice cover.

  2. Katie Whitten says:

    Cool! Thank you for sharing!
    I am involved with The Friends of Silverwood Park (FOSP), the newest park in Dane County. We are located in the far South/East corner of the county. The park borders Rice Lake for one mile and about one half of Sweet Lake.
    We would be exsteemly supportive if you would be interested in research of either lake.
    Thank you,
    Katie Vance-Whitten
    FOSP president

    • timcampbell says:

      Hi Katie. I’ve passed your comment along to Paul. I’ll post an update if he has anything else to add. Thanks for reading!

  3. Gary Mueller says:

    Has anyone been able to treat Invasive EWM under the Ice? One 100 square foot area of treatment 10’x10′ would be a great experiment without a lot of collateral damage potential. If it worked, EWM might become a controllable invasive.

    • timcampbell says:

      Hi Gary. Thanks for the comment. I again turned to Paul Skawinski for an answer:

      Although EWM often persists under the ice, its biological activity is greatly reduced. In order to kill perennial invasive plants like EWM, herbicides must be absorbed by the plants and translocated to their roots. Plants need to be actively growing for this to happen. This is why herbicide treatments for EWM control are typically conducted in the late spring, when EWM is very active, but many natives are still dormant.

  4. Hillary Weiss says:

    What a great idea to look beneath the ice to learn more about the aquatic plant species. Great article, I enjoyed reading it.

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