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Northwoods researchers collect lake-bottom muck, seeking an explanation for wild rice decline

Ben Meyer
Trout Lake Station researcher Susan Knight, right, and Northern Michigan University student Erin Matula examine a wild rice plant on Wild Rice Lake in Vilas County.

On a clear and warm morning last week, Erin Matula braced her legs against one of the seats of a small, tipsy, flat-bottomed boat.

She leaned over the side and slammed a tall, clear plastic pipe into the water.

Then, using all of her body weight, she forced the pipe down into the sediment below the shallow current.

“It’s like one brute effort,” she explained. “If you can get it with one push, then you’re set.”

Susan Knight helped steady the boat as Matula jammed the pipe downward.

“Erin is our designated get-wet, get-cold person,” Knight said.

“Yes, so I’m trying to get as much mud, the sediment, as tall of a sediment core as I can,” Matula agreed.

Matula, an undergrad at Northern Michigan University, capped both ends of the tube and was able to rest for a minute or two. She had pulled up a sediment core from underneath shallow water on Wild Rice Lake, which touches both private land and the Lac du Flambeau Reservation in Vilas County.

Knight, a researcher at the UW-Madison Trout Lake Station in Boulder Junction, says Wild Rice Lake is aptly named.

“[Where we are] is the Trout River coming into another lake. For whatever reason, this seems to be moving, but slowly, and mucky,” Knight said. “That’s what wild rice really likes.”

Knight, Matula, and Gretchen Gerrish were aboard the small boat in an effort to shed light on a mystery of wild rice. That is, they hope to figure out why it’s disappearing from Northwoods lakes.

The wild rice crop in our area was the worst in 35 years, according to the Great Lakes Indian Fish and Wildlife Commission (GLIFWC).

It’s a symbol of the decline of wild rice over the last several decades. Northwoods researchers still aren’t fully sure about what’s causing the decline, but they hope to find out through studies like this one.

Ben Meyer/WXPR
The well-named Wild Rice Lake seems to be a healthy producer of wild rice. The tall plants naturally die back by October.

By this time of October, the tall wild rice stalks have died back, but overall, Wild Rice Lake is a pretty healthy lake for the crop.

However, that’s true for fewer and fewer local lakes.

“In the last few years, they’ve all just been failed, failed, failed,” Knight said. “One after another.”

Since 1985, Wisconsin has lost half of its wild rice acreage, GLIFWC estimates.

That has diminished a resource vital to Ojibwe sustenance and culture.

“We wanted to follow [the wild rice plant] from the very beginning to see if we could untangle at what stage is it most vulnerable,” Knight said.

Wild rice is an annual plant, relying on seeds dropped in the fall to regenerate the next spring.

Gerrish, the director at Trout Lake Station, said the team has been observing and documenting the wild rice life cycle on six lakes all year.

“There’s kind of a normal progression through seedling. Then it’s all underwater growth. Then, when it hits the surface, it pops a small stem out. Then it produces what are called floating leaves,” she explained.

Afterward, the wild rice plant sprouts the familiar stalk as the rice grains ripen.

Some of the seeds drop again to the lakebed, ready to grow the next year.

Ben Meyer/WXPR
Erin Matula uses brute strength and body weight to force a sampling core tube into the sediment at the bottom of Wild Rice Lake.

That’s where Erin Matula’s October work comes in.

Those sediment cores, collected by pure strength, should hopefully contain viable wild rice seeds ready to germinate next year.

That would be evidence of a regenerating resource.

These cores will head back to the lab for examination of their contents.

“We’ll sieve them and look just for the rice grains. We’ll count any viable rice seed, any husk or nonviable rice seed that we find, and quantify that in each slice in each of those cores,” Gerrish said.

The early results from the cores were perplexing: husks far outnumbered the few viable seeds.

That led the researchers to decide they needed a broader survey area to draw solid conclusions. They’re working on that plan now.

Ben Meyer/WXPR
A sediment core after it is retrieved from the bottom of Wild Rice Lake.

Knight has two main hypotheses to explain the decline in wild rice.

First, she said, it could be disturbance by waterfowl, especially the rising number of swans in the Northwoods. Or, perhaps other vegetation, like pond lilies, choke out wild rice if the rice has a bad year. Further study may show whether either of those theories appear to be the best explanation.

The study will continue through the next few years.

If the study is successful, the researchers may find the point of disruption in the circle of life that’s hurting wild rice.

Maybe that disruption can be a clue to reverse the decline across the Northwoods and instead encourage a revival.

“If [wild rice is] doing well, it’s doing really well. If it’s doing poorly, it’s doing really poorly,” Knight said. “It goes into like a death spiral.”

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Ben worked as the Special Topics Correspondent at WXPR from September 2019 until November 2021. He now contributes occasionally to WXPR. During his full-time employment, his main focus was reporting on environment and natural resources issues in northern Wisconsin and Michigan's Upper Peninsula as part of The Stream, a weekly series.