Field Notes
Field Notes

"Invisible” species of exotic algae threatens to poison Minnesota lakes

Tuesday, November 6, 2018
Posted by
Greg Seitz

Research Station scientists spent this summer searching Minnesota lakes for Cylindro — blue-green algae originally from the tropics that could cause more problems for the state's beloved clean waters.

Illustration by Hailey Sauer, Environmental Research Intern
St. Croix Watershed Research Station

Algae are part of every body of water in Minnesota. These simple aquatic plants are natural, and play an important part in the food web — even the “blue-green” species notorious for creating toxic water. They can be found from the highly fertile prairie lakes of the southern part of the state to the rocky lakes on the Canadian border.

Blue-green algae cause problems when conditions are just right for a massive bloom, usually in late summer when the water is warm and there is lots to eat. Many lakes in Minnesota suffer from such blooms.

Recent studies have shown that climate change — warmer weather, longer growing seasons, and new precipitation patterns — along with agricultural practices, development, and a million more reasons, is making harmful algae worse than ever. 

Now there may be a new factor.

Adaptable algae

Front to back: Dr. Mark Edlund, Hailey Sauer, and Dr. Adam Heathcote, collecting data on South Center Lake. (Photo: Mark Edlund)

A species of algae originally from tropical areas, and that's recently been popping up all around the Great Lakes Region, has now been found in Minnesota.

Cylindrospermopsis raciborskii (Cylindro for short) was first found in a few lakes across the state, starting in 2013. Despite its tropical origins, it seems capable of surviving in cooler climates. Some forms of Cylindro can produce harmful toxins like other blue-green algae, poisoning people as well as wildlife. 

And the same conditions that cause other harmful algae blooms could also be responsible for the spread of Cylindro.

“It is likely that recent years with warmer summer temperatures and increased nutrient pollution have provided a new niche for this species to invade,” says St. Croix Watershed Research Station scientist Dr. Adam Heathcote. 

While other toxic algae blooms usually create a big green smear on the water, Cylindro often blooms several feet under the surface of the water. That means it can be present and producing toxins without any visual sign.

Because algal toxins are dangerous to people and animals, and have resulted in several dog deaths in recent years, the people of Minnesota are spending significant time and resources trying to understand blue-green algae, and to minimize blooms by reducing nutrient runoff.

Cylindro census

Dr. Mark Edlund and intern Hailey Sauer record data on Portage Lake showing the green waters of a cyanobacteria bloom. (Adam Heathcote)

Cylindro was first found in South Center Lake in Chisago County and Madison Lake in Blue Earth County in 2013. While Research Station scientists detected its toxins in several other lakes during other research, they have not yet found the organism.

So they spent spent much of August and September this year — Cylindro’s bloom season — in a boat, collecting water samples from lakes across Minnesota. They were launching  the first systematic study of where Cylindro and its toxins are found in Minnesota.

As a sign of the issue’s statewide significance, the research project is funded by the Minnesota Environment and Natural Resources Trust Fund, based on a recommendation by the Legislative-Citizen Commission on Natural Resources.

This first survey is focusing on Minnesota’s Sentinel Lakes which were selected to be representative of the diversity of lakes that exist all across Minnesota. They will analyze water samples for toxins and also under a microscope to find any evidence of Cylindro. It will also help build on a recent two-year project studying when, where, and why blue-green algae bloom in the state.

To understand more than just what lakes are already infested with the organism, they're trying to pinpoint when Cylindro first showed up and when it has created toxins — and why.

Taking tubes of mud from the bottom of the lakes lets them look at back at this history. The toxins from Cylindro have been shown to be preserved in lake mud for thousands of years.

The team will be out this winter taking more sediment cores through the ice. They will also start analyzing all the data.

Ultimately, the researchers hope to use these data to predict when and where Cylindro may spread and produce toxins. This will help understand the connections between land use, climate, and other forces that affect its growth, and guide a strategy to protect Minnesota’s lakes.

Funding for this research was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative‐Citizen Commission on Minnesota Resources (LCCMR).

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