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Just Say No to Didymo
August 20, 2009
Get past its egghead name, didymo (Didymosphenia geminata), or its more colorful nom de guerre, rock snot, and you encounter one of the newest threats to Maine’s environment.
Whichever handle it goes by, this invasive alga targets Maine’s pristine and flowing waterways—the kinds of rocky bottomed streams and rivers sportsmen from around the world long to fish.
And that’s the risk. Anglers coming from away may play host to microscopic cells of this pest that attach to waders, fishing gear or anything else in contact with infested waters.
When established, didymo can multiply aggressively to eventually smother entire stream or river beds with a thick coating of vegetative goo that lives up to its vernacular name, at least in appearance. (Actually, it has the texture of wet wool.) Biologically, it is an invasive species that displaces the native river-bottom habitat including aquatic insects relied upon by trout and other riverine natives.
Once didymo moves into a stream or river, it’s there forever; it cannot be eradicated.
The distribution and number of nuisance blooms of didymo has increased dramatically in the past 20 years across the U.S. as well as throughout angler-coveted regions of New Zealand, Scotland, Scandinavia and the Pacific Northwest. One can argue a cause and effect relationship between glossy brochures for exotic cold-water fishing excursions and the explosive spread of didymo.
Maine is surrounded by waters infested with didymo. New Hampshire, Vermont, Massachusetts and the Canadian Maritimes all have infestations, according to their respective environmental officials. Maine biologists think that, at least so far, the booger…er…bullet has missed the Pine Tree State. While good news, this also means Maine has the most to lose.
That’s why anglers need to do their part to prevent further infestations. These measures are more than suggestions; they’re essential to preserving Maine waters. Fortunately, they’re as simple as check, clean and dry all gear, especially waders or other footwear. Here’s how:
Check: Before leaving a river or stream, check your gear and remove all obvious clumps of algae, looking for hidden clumps. Leave them at the affected site. If you find any later, dispose of all material in the trash.
Clean: At home, soak and scrub all items for at least one minute in hot (140 degrees F) water and a five percent solution (one cup per gallon of water) of dishwashing detergent. Felt-soled waders and other absorbent material are especially attractive to alga cells, so soak them for at least 30-40 minutes. When in the field, a coldwater soak in five per cent salt works.
Dry: If cleaning is not practical, after the item is completely dry, wait an additional 48 hours before contact or use in any other waterway. Because footwear is always suspect for stream-to-stream transport of didymo, consider buying an extra pair of non-felt waders and make it a practice to sanitize one while fishing in the other. Looking for an excuse for this new purchase? Just say no to didymo!
Paul Gregory is an Environmental Specialist for the Maine Department of Environmental Protection’s (DEP) Invasive Species Program. In Our Back Yard is a weekly column of the Maine DEP. E-mail your environmental questions to firstname.lastname@example.org or send them to In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333. In Our Back Yard is an informational column of the Maine Department of Environmental Protection. E-mail your environmental questions to email@example.com or send them to In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333.
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