This species has been detected in Michigan.
(Didymosphenia geminata)
Didymo (also known as "rock snot") is a microscopic algae (diatom) that produces stalks that form thick mats on hard surfaces like rocks in stream beds. It looks and feels like white or tan/brown wet wool. It ranges from small cotton ball-sized patches to thick blankets and long ropy strings that flow in currents. Although it is often referred to as "rock snot," didymo is not slimy.
The following images can help identify didymo. Click on each photo for descriptions.
If you see suspect didymo, report it through the Eyes in the Field online reporting system. Note the location of the suspect didymo and be sure to include at least one photo of the algae to help in verification.
Didymo thrives in low-nutrient cold water rivers and streams. Unlike blue-green algae, didymo’s presence does not indicate a decline in water quality. Researchers are still working to determine what triggers didymo’s nuisance blooms.
Native: Far northern regions of Europe, Asia and North America. Didymo is likely native to Lake Superior and parts of Canada.
U.S. distribution: Scattered populations exist throughout the United States, including New England, the Mid-Atlantic Region, and the Western U.S.
In Michigan: Didymo cells haves been documented in the Great Lakes Basin and Michigan waters in low abundance. Nuisance blooms have been documented in Michigan in the Boardman, Upper Manistee and St. Marys rivers. Didymo may be present but undetected in other rivers or streams. Follow the Clean, Drain, Dry instructions below after every visit to a water resource..
Under the right conditions, prolific growth patterns result in thick mats that can cover river and stream bottoms. Didymo mats alter habitat and food sources for fish and can make recreation difficult or unpleasant. Mats can also foul water intakes and fishing gear as well as impact fishing access and wading.
Didymo cells can be transported on boats, anchors and fishing gear such as waders, felt-soled boots and nets.
Currently, there is no effective method to eradicate didymo from the environment.
Always Clean, Drain, and Dry your waders, boots, boats and other gear between trips or before moving to a new body of water. Take extra precaution in areas with known or suspected didymo or New Zealand mudsnail infestations. In addition to removing debris and mud, the State of Michigan recommends using a chemical disinfectant to achieve maximum decontamination for didymo and New Zealand mudsnail. Possible disinfectants with documented effectiveness for these species include:
Any chemical disinfectants should be applied to waders and gear on land, at a reasonable distance from the water, to avoid accidental discharge into surface waters.
