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Thanks to climate change, rock snot won’t be slipsliding away

Staff writer

If global warming is a myth, how come there’s so much snot in my favorite fishing streams?

Scientific American reported last week that rock snot, a slimy algae that began appearing in West Virginia trout streams in 2008, is not an invasive species as previously thought, but a native algae strain that previously bloomed here, and at other sites across the United States, only rarely, if at all, but now is in an unprecedented growth spurt due to climate change.

Sightings of rock snot, or Didymosphenia geminate as it is scientifically known, began spreading through the western United States early in the current millennium, eventually extending into the east. Initially, biologists believed “didymo,” the algae’s more pleasant but much less descriptive nickname, was an exotic organism, carried from stream to stream in the anti-slip matting on the soles of felt-tipped waders. During the past few years, anglers were urged to disinfect their waders after use to prevent rock snot’s spread.

As its nickname suggests, rock snot looks slick and slimy, but when handled, has a rough, cottony feel. It comes in shades of light brown and white, and it covers river rocks in thick mats, affecting access to stream nutrients enough to make “small” the only available size option for aquatic invertebrates -- a prime source of food for fish. To make matters worse, rock snot blooms enhance the habitat for a type of worm known to be a host for trout-killing whirling disease.

Large accumulations of didymo (sounds like a rapper’s name to me) made their first appearances in West Virginia in the Elk River upstream of Webster Springs six years ago. Soon, it began showing up in other prime trout waters like Seneca Creek in Pendleton County and Glady Fork and Gandy Creek in Randolph County.

While initially thought to be a new strain of algae spread by fishermen, recent studies have indicated that rock snot has existed in streams across North America and other parts of the world for thousands of years, but until now, the environmental conditions that cause its visible growth were rare, or possibly absent.

While growth in most types of algae is stimulated by high levels of phosphorus and other nutrients, didymo blooms take place when phosporus levels are present in streams in low concentrations, due to human-induced environmental changes.

The state Division of Natural Resources has done a lot to keep trout populations viable in streams affected by acid precipitation by installing water-powered liming stations along the main stems of waterways, and dumping piles of acid-neutralizing limestone sands in headwater streams.

Dartmouth College biology professor Brad Taylor, the lead author of the study cited by Scientific American, said the odds of wiping out rock snot are slim to none. “Nothing can be done to eradicate this microorganism,” he said. “It has been here and it’s here to stay.”

But in time, maybe the DNR will find it worthwhile to try to control rock snot by adding phosphorus to the limestone sand it currently uses to treat streams.

Or better yet, add Sudafed to the limers and call me in the morning to go fishing.

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