Researchers investigating harmful duckweed on Minnesota ponds

ST. PAUL, Minn. -- There's something thriving on stormwater ponds across Minnesota and it's catching the attention of researchers and appears to be a big problem.

It may look like blue-green algae, but it's not - it's actually duckweed, which is the smallest flowering plant out there.

And it loves to grow on little ponds across the state. But University of Minnesota researchers now know, it's actually harmful.

They've been testing ponds around the metro with a little bucket device to see the gasses ponds with duckweed emit. They found ponds with duckweed on them emitted over three times as much methane than ponds without it.

Methane is a greenhouse gas that's 30 times more potent than carbon dioxide when it comes to warming.

"Pretty much all freshwater bodies are emitting carbon dioxide and methane as a whole just because they receive all the runoff from the land all the leaves from woods run into - what we found is these smaller ponds stormwater ponds are doing this at a rapid rate just because they see so much more runoff," said University of Minnesota Ph.D. candidate Joe Rabaey.

Now researchers are shifting their work to look at solutions. For example: would a fountain break the growth up and cut down on emissions? Can they just scoop it out of the ponds? And would that create different problems?

They're hoping to find out and find a helpful solution. Researchers will also explore what happens throughout the year. 

There are also positives. It looks like the duckweed filters out metal contaminants from stormwater ponds. The duckweed stores it in its biomass and then you can harvest it off.