From the Connecticut DEEP

Your help is needed to prevent the spread of didymo (Didymosphenia geminata). This highly invasive freshwater form of algae (also called “rock snot”) has now been found in popular trout streams located in a number of northeastern states (New Hampshire, Vermont, New York, Pennsylvania, Maryland, West Virginia and Virginia).

Didymo has the potential to alter food webs and degrade habitat in many Connecticut trout streams.

Didymo is typically found in shallow streams with rocky substrate.

Thought to be native to northern regions of Europe, Asia and North America, didymo originally was found only in cold, clear, low-nutrient waters. Didymo’s geographical and ecological ranges have been expanding, and now also include warmer and more nutrient-rich waters.

The occurrence and intensity of blooms are also increasing. It is currently unclear why.

The microscopic didymo cell produces a stalk to attach to the substrate. During blooms, didymo can produce large amounts of this stalk material, forming thick mats of cottony material that feels like wet wool on the bottoms of rivers and streams. These mats can potentially smother aquatic plants, mollusks, destroy invertebrate and fish habitat, and impact existing food webs.

Anglers are considered an important vector responsible for the recent spread of didymo. The microscopic cells can cling to fishing gear, waders (felt soles can be especially problematic), boots and boats, and remain viable for months under even slightly moist conditions.

What you can do to prevent the spread of didymo:

• CHECK: Before leaving a river, stream or lake, remove all obvious clumps of algae and plant material from fishing gear, waders, clothing and footwear, canoes and kayaks, and anything else that has been in the water and look for hidden clumps. Leave them at the site. If you find any later; treat and dispose of all material in the trash.

• CLEAN: Soak/spray & scrub boats and all other “hard” items for at least one minute in either very hot (140°F) water, a 2% bleach solution, or a 5% dishwashing detergent solution. Absorbent materials such as clothing and felt soles on waders should be soaked for at least 40 minutes in very hot water (140°F), or 30 minutes in hot water (115°F) with 5% dishwashing detergent. Freezing solid will also kill didymo.

• DRY: Drying will also kill didymo, but items must remain completely dry (inside and out) for at least 48 hours.
For more information on didymo:

• US EPA Region 8 website: http://www.epa.gov/region8/water/didymosphenia.

• Biosecurity New Zealand website: http://www.biosecurity.govt.nz/didymo






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