July 12, 2008

Invasive ‘Rock Snot’ Found in Vt’s Mad River

ELIZABETHTOWN -- Didymo, an invasive species also known as 'rock snot,' has been found in the Mad River, a waterway that runs through the heart of Vermont.

A freshwater diatom, or microscopic alga, didymo erupts in noxious "blooms" covering rocky river beds with brown, clumpy growths that feel like wet wool, according to the Vermont Agency of Natural Resources. It is described as looking similar to a sewage spill with wet toilet paper streaming in the waterway.

According to a press statement, Vermont water-quality scientists confirmed the presence of didymo in the Mad River, the first time the invasive freshwater alga has been found within the Lake Champlain Basin.

Vermont scientist Dr. Leslie Matthews said a citizen spotted the didymo and provided a sample for testing.

Matthews said her investigation found didymo has spread in the Mad River in an area between Riverwatch Lane and just upstream of the bridge leading into Warren Village.

"Didymo is extensively coating the rocks with 75 to 100 percent coverage and up to 1 to 2 centimeters in thickness," Matthews said. "I have not yet investigated other sections of the river but would expect that additional areas of bloom are likely present in the river."

River conservationists are very concerned about the potential for spreading rock snot.

"The discovery of didymo in the Mad River is great cause for concern," said Caitrin Noel, watershed coordinator for Friends of the Mad River. "We are working hard to learn all we can about the extent of this, how to address it and will continue to study this in the future."

In a phone interview Friday, Noel said the Friends of Mad River board of directors just had a meeting and discussed the didymo.

"We're not sure yet how far it goes," she said. "We haven't had time to map the watershed. The general feeling is we're concerned about it, but we want to stay optimistic."

The organization has done a lot of outreach about didymo, she said.

"But the White River is so close to here, if you think about it, it's inevitable."

Didymo has specific habitat requirements, and needs shallow, fast-moving water with a rocky bottom to survive.

"It's not going to be able to live in every place in the Mad River," Noel said.

It dies back in the winter, but returns in the spring.

"There's nothing you can do about it, once its there. Scientists are not even sure that it hasn't always been here and just all of a sudden blooming now."

But the river keepers don't want to raise alarm.

They prefer to teach people how to disinfect gear used in the river.

"We don't want to start panic," Noel said.

"We don't want people to become afraid to use the resource. That's going too far, especially because we don't know too much about this."

Friends of Mad River plan to put signs up and ramp up the education, so paddlers and anglers can learn how to clean their gear and not spread didymo to other waterbodies.

"We're going to do the best we can," Noel said.

The microscopic algae is spread by boats, paddles and infected gear.

"Our biggest focus right now is spread prevention and outreach," Noel said.

"The more we can educate our community about this, the better chance we have in preventing further spread upstream and into the headwaters, or into other water bodies."

Vermont's Agency of Natural Resources said scientific studies conducted around the globe "have yet to show conclusively that didymo has significant impacts to trout fisheries. However, it remains a priority to limit the algae's spread throughout the region, as a precaution."

But the algae can significantly alter the appearance and river ecosystem; and is considered a major nuisance-species threat.

As of fall 2007, didymo had infiltrated the northeast from just north of Lake Francis in Pittsburg, N.H., to Northumberland, N.H., and along portions of the White River in Vermont downstream from the Stony Brook confluence. Until 2006, it was unheard of in the northeastern U.S., Vermont Agency of Natural Resources said.

"It was discovered during the summers of 2006 and 2007 in the Batten Kill; in 2007 in the Connecticut River, the White River and the Delaware River system; and in 2008 in the Gunpowder River in Maryland."

There are no known methods of eradicating didymo once the infestation is established.

Paddlers bringing equipment from one area to another throughout the region's river system can minimize the spread of didymo by following best practices and disinfecting their gear when using Vermont water, ANR advised.

"Disinfection and best practices not only help to reduce the spread of didymo, but other invasive species and pathogens such as VHS (viral hemorrhagic septicemia) and whirling disease, as well."

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New York State Department of Environmental Conservation outlined measures to prevent the spread of didymo:

Check: Before leaving a river or stream, remove all obvious clumps of algae and look for hidden clumps. Leave them at the affected site. If you find any later, do not wash them down drains; dispose all material in the trash.

Clean: Soak and scrub all items for at least one minute in either hot (140 degrees F) water, a two percent solution of household bleach or a five percent solution of salt, antiseptic hand cleaner or dishwashing detergent. Be sure that the solution completely penetrates thick absorbent items such as felt soled waders and wading boots.

Dry: If cleaning is not practical, after the item is completely dry to touch, wait an additional 48 hours before contact or use in any other waterway. Check thick absorbent items closely to assure that they are dry throughout. Equipment and gear can also be placed in a freezer until all moisture is frozen solid.

NOTE: If cleaning, drying or freezing is not practical, restrict equipment to a single water body.

While DEC recommends anglers always take these precautions, it is especially important that any gear used out of state be treated before using in New York waters. There are currently no known methods for controlling or eradicating didymo once it infests a water body.

Believed to be native to far northern regions of Europe and Asia, didymo has been expanding its range and tolerance for warmer, more nutrient-rich water conditions during recent years in Europe and North America.

Didymo was discovered in New Zealand, in 2004, and within 18 months it had spread to 12 rivers on the South Island, forming nuisance blooms at several locations. New Zealand Biosecurity has instituted severe penalties for intentional spread of the algae.