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Didymo and Aquatic Invasive Species Prevention Techniques

What is Didymo?

Didymo - Didymosphenia geminata - a.k.a rock snot is an invasive freshwater diatom (microscopic algae) that can form extensive 'blooms' on rocky river beds. The blooms produce unsightly stalks that literally look like snot.

Didymo uses the stalks to attach to rocks and plants in the river system. These stalks can form masses 10-12 inches thick on the river bottom, and trail for lengths of 2-3 feet in the current. When blooming Didymo can smother aquatic life forms including aquatic insects and antive algae. Didymo stalks are problematic as they can persist for several months after algal cells have died off.

Known Didymo Locations in the Northeast

Didymo has been found in the following rivers:
Upper Connecticut River
White River
Locust Creek
Mad River
Battenkill River (VT and NY)
Delaware River (NY)
Mohawk River (NH)

Prevent the Spread of Didymo and other Aquatic Invasive Species

The following spread prevention techniques will not only help prevent the spread of didymo, they will also help stop the introduction of other aquatic invasive species such as Whirling Disease and Viral Hemorrhagic Septicemia (VHS) a deadly fish virus that effects over 25 species of fish.

Check

Before you leave the river, check boats, life preservers and fishing gear for clumps of algae or sediment; leave it at the access point.

Clean

You can either clean your gear at the site or at home. Choose the treatment best suited to your situation and gear. Make sure to properly dispose of bleach solutions (if using them) - by pouring them down your drain at home.

Boats and other Non-absorbant Items

Scrub all surfaces for 2 minutes in a 2% bleach solution (1/3 cup of bleach/gallon water) or a 5% salt solution (1 cup salt/1 gallon of water).

Absorbant Items such as felt-soled waders and life-jackets

Soak items for at least 30 minutes in dishwashing soap and very hot water.

Dry

This is best for boats and non-absorbant items. They must be completely dry to touch inside and out and then be left to dry for another 48 hours. Slightly moist didymo can survive for months on gear. Given Vermont's perpetually rainy summers, it's best to wash your boats and paddles.