First Confirmation of the Aquatic Nuisance Algae in New York State

New York State Department of Environmental Conservation Commissioner Pete Grannis announced today that didymo is confirmed to be present in a section of the Batten Kill in Washington County. This is the first known presence of this aquatic nuisance algae, also called “rock snot” in New York State.

Unlike many other aquatic nuisance plants Didymosphenia geminata, grows on the bottom of flowing and still waters. It can develop thick mats even in fast flowing trout streams. Fishing becomes difficult; the abundance of bottom dwelling organisms declines; and trout and other fish that feed on those organisms also decline.

“The presence of didymo in New York illustrates the need for all of us to be diligent in preventing the spread of exotic invasive species,” said Commissioner Grannis. “The practices we encourage – Check, Clean and Dry – must become habit of all outdoor recreationist to stop the spread of invasive plants, animals and diseases.”

The Batten Kill is a celebrated trout stream as well as a popular watercourse for kayaking, canoeing and tubing, that meanders 29 miles from Vermont to the Hudson River. Didymo, which resembles rotting cardboard when exposed and dried, was observed in a section around and downstream of the Route 22 crossing near the Village of Salem. Vermont has also confirmed the presence of didymo in a section just upstream of the border with New York.

The microscopic algae cling unseen to waders, boots, boats, lures, hooks, sinkers, fishing line and other fishing gear, and remain viable for several weeks under even slightly moist conditions. Absorbent items, for example the felt-soled waders and wading boots commonly used by stream anglers, require thorough attention as discussed below. Anglers, kayakers and canoeists, boaters and jet skiers can all unknowingly spread didymo.

DEC is urging anglers and other water recreationists to Check, Clean and Dry to prevent the introduction and 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.

Accompanying this expansion have been increasing reports of massive blooms that reach nuisance levels, forming thick mats of cottony material on the bottoms of rivers and streams that can potentially smother aquatic plants and destroy fish habitat.

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.