Dipping a toe into local streams is normally a great experience, unless said toe comes into contact with an extra-slimy surface.
Slippery rocks are of course mostly caused by algae, which grows on any hard surface in a waterway if the conditions are right. Even though they can sometimes be somewhat of a nuisance, algae play a huge role in the regulation of our atmosphere. Due to their photosynthetic efficiency and global abundance, algae currently produce about half of the oxygen we breathe.
They are also a food source for a large number of aquatic organisms. Although there is a healthy variety of naturally occurring algae in the area, we are also currently in the midst of an invasion by a significant algal threat. Believed to have origins in the far reaches of the northern hemisphere, a photosynthetic microbe known as Didymosphenia geminata has seen rapid increases to its range in the past 50 years or so.
Commonly called didymo for short, this organism is bewildering scientists with the rate of its spread. Unfortunately, this holds true for our own backyards as well, since researchers recently identified growths of didymo in the Tuckaseigee River in Jackson County.
Unlike most local algae, didymo does not take root directly onto an acceptable surface. Instead, it suspends itself from a long tether attached to a rock or plant, almost like an underwater kite. When it was first discovered, didymo seemed to play well with others, and did not venture far from its native range. Its current spread has some scientists speculating that a new, more aggressive genetic variation of the species recently evolved.
Able to reproduce sexually as well as through asexual vegetative cell division, it doesn’t take long until there are dense, slimy masses of these algal ‘strings’ in areas where didymo has taken hold. Hence, the other common name for didymo, rock snot.
These masses have rather profound impacts on the ecosystems in the freshwater streams, rivers and lakes that are affected. Studies have found that dense didymo mats exclude most larger organisms from the area and tend to completely disrupt the food chain. This leads to changes in the sediments and nutrients in the water, which causes a ripple effect that can alter the lives of wildlife like birds, fish and insects even far downstream from the outbreak.
Each individual rock snot organism is very tough, and can survive outside of a stream for almost 50 days with the right conditions. This makes them ideal stowaways on fishing equipment, clothing and boats.
Although it spreads rapidly on its own, unaware humans are believed to be a contributor to this species’ rapid invasion. If seen on any rocks, plants or other aquatic surfaces, it is possible to scrape didymo off by hand to help slow its growth. If you fish, wade or float in any local freshwater waterways, the most important thing you can do is check and clean your gear after you’re done, and absolutely before entering another body of water.
Even if you don’t see anything, the small size of these organisms warrant decontamination anyway. Luckily, it’s simple to do. Freezing equipment for several days works, as well as heating to at least 140F for one minute. Absorbent items take a bit longer – soak in hot water for a half hour. This is one reason why felt-soled wading boots are going out of style.
If you cannot perform these methods, you can also simply let the equipment completely dry for at least 48 hours. If we all do our part, we can hopefully slow the local spread of the nefarious didymo.
Brannen Basham is a writer and horticulturalist. Together with his wife, Jill Jacobs, he owns Spriggly’s Beescaping, focused on nature education and habitat restoration. He recently published his first book, “A Guide to the Wonderful World Around Us: Notes on Nature.” For more information visit www.sprigglys.com.