Didymo Intrudes On Connecticut’s Waters

By Kendra Bobowick

The new word on the water is “didymo,” which is a nickname for something less attractive: Didymosphenia geminata.

“It’s rock snot,” said resident Joe Hovious, a member of the local Trout Unlimited chapter and a conservation commission member. Due to the foamy layer of algae that forms on the bottoms of streams, didymo is a “major environmental issue,” he said. “It shuts off” the stream’s ability to maintain good health.

The algae likes the cool, rocky bottoms in fresh water habitats, which are home to macroinvertebrates and trout.

Since its detection in the United States in 2007, the invasive freshwater algae has surfaced in New York, New Hampshire, Pennsylvania, Vermont, and Virginia, and most recently in Connecticut.

The Department of Environmental Protection first learned from several anglers on March 18 of didymo’s possible presence in the West Branch Farmington River, according to a DEP release.

In late March, Vermont officials confirmed the presence of didymo in a Farmington River water sample.

“It’s pretty nasty stuff,” said Todd Bobowick with the US Department of Agriculture’s Natural Resource Conservation Service. Because the algae “really likes the cold clear [water] and sunlight,” Mr Bobowick warned that fishermen are likely the main means for spreading the didymo. “They walk into a river, fish, pick up the [didymo] spores, and walk into another river,” he said.

The DEP is currently handling public education on this invasive, but Mr Bobowick is prepared to develop a biosecurity protocol for state waters and hatcheries. Alerted recently to the algae’s presence in Connecticut, he notes that aside from the West Branch Farmington River, it “shouldn’t be anywhere else.”

The DEP Deputy Commissioner Susan Frechette said, “Extensive blooms of this organism can harm the river ecosystem and decrease its recreational and economic value.” DEP Bureau of Water Protection and Land Reuse staff surveyed a number of sites in the Farmington River and major tributary where they found additional clumps of didymo.

“There’s no practical way to remove it from a river,” she said.

According to DEP information, didymo is most frequently found in cold, relatively shallow streams and rivers having a rocky bottom — characteristics that are also typical of good trout habitat. During blooms, didymo can form thick mats of material that feel like wet wool and are typically gray, white and/or brown, but never green in color.

These mats form on the bottoms of rivers and streams and can potentially smother aquatic plants, aquatic insects and mollusks, impact fish habitat, and alter aquatic food chains. Dense mats of didymo can also reduce the recreational and aesthetic value of the affected river.

Taking Precautions

Humans are the primary factors spreading the didymo. Anglers, kayakers and canoeists, boaters and jet skiers can all unknowingly transfer the algae. The microscopic cells can cling to fishing gear, waders, boots, and boats, and remain viable for months under even slightly moist conditions.

Resident Ann Astarita, who works with the Candlewood Valley Trout Unlimited Chapter, urges anyone leaving any river to check, clean and inspect their clothing and equipment.

“Anyone enjoying the water should make sure that invasives don’t hitch a ride,” she said.

Mr Hovious explained that some states have made it illegal to wear certain fabrics in the water that most easily carries the algae. The measure is meant to “keep people from transferring it from place to place.”

To prevent the spread of didymo to additional waters, the DEP asks that anglers, especially those who also fish the Farmington River or streams outside Connecticut, and other users take measures to reduce the invasive’s spread.

Examine clothing and equipment before leaving a river, stream, or lake.

Soak and/or spray and scrub boats and all other hard items for at least one minute in either very hot water, a two percent bleach solution, or a five percent dishwashing detergent solution. Freezing thoroughly will also kill didymo.

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.

The above procedures will also be effective against other unwanted organisms, according to the DEP.

Individuals wishing to report possible sightings of didymo and other aquatic nuisance species can contact DEP’s Inland Fisheries Division at 860-424-3474. More information on didymo and other aquatic nuisance species can be found on the DEP website (www.ct.gov/dep) or in the Connecticut Angler’s Guide (www.ct.gov/dep/lib/dep/fishing/anglers_guide/anguide.pdf).

An excellent source for detailed information on didymo is the Biosecurity New Zealand website www.biosecurity.govt.nz/didymo), and the Trout Unlimited website (www.TU.org) also has articles on didymo.