July–August 2023


A Deeper Dive

This project takes a close look at native algae called stoneworts.

Keith Goetzman

You may have heard of invasive starry stonewort,  a plant-like algae that can be a threat to lakes where it’s found. But Minnesota also has many native stonewort species that help make our lakes what they are. 

These stoneworts grow in many Minnesota lakes, bringing benefits that include food, habitat, oxygen, and clearer water. In lakes such as Leech Lake, native stoneworts are the main vegetation, with some species growing in football field–sized beds on the lake bottom.

A new study aims to find, identify, and catalog this rich diversity of lake-bottom flora across Minnesota, using methods that include an underwater drone and high-tech DNA analysis.

“This baseline inventory is critical for species and habitat protection because we don’t know how many different stonewort species occur in Minnesota or their habitat requirements,” says project manager Donna Perleberg, Minnesota DNR aquatic plant ecologist. 

Study products will include a detailed stonewort identification field guide for lake surveyors, botanists, conservationists, and resource managers. Specimens will be available for viewing online at the Bell Museum’s Biodiversity Atlas.

The project, now in its second field season, is a collaboration between the Minnesota DNR, the New York Botanical Garden, the Leech Lake Band of Ojibwe, Leech Lake Tribal College, and the Bell Museum. Funding for the project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).

Though much of the fieldwork is decidedly old school—wading and raking up samples of greenery from 500 survey sites—the study has high-tech components that include an underwater drone to photograph and collect samples in deep water, and state-of-the-art DNA analysis that can parse species differences that can be challenging to discern otherwise.

The DNA analysis is being done at the New York Botanical Garden, whose research aims to fill out the details on the biological Tree of Life. Minnesota’s stoneworts are a branch on that tree, says Kenneth G. Karol, associate curator at the garden.

“It’s really a good complement, the taxonomic and the systematic expertise that we have coupled with Minnesota’s passion for understanding and conserving this really amazing resource, the lakes and the things that inhabit them,” he says.

The Leech Lake Band of Ojibwe is contributing to field sampling on Leech Lake and is interested in using new knowledge about stoneworts across its reservation waters, says Kate Hagsten, plants program director for the band.

“The diversity of each one of those lakes is unique. And the [stonewort] species themselves have their own little niches,” she says. “It’s an opportunity to highlight those unique features for each of the lakes.”