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Didymo – “Rock Snot” (Didymosphenia geminata)
Didymo – “Rock Snot” (Didymosphenia geminata) a rampantly growing fungus, said to be endemic in many countries, but is now spreading rapidly in other countries, especially New Zealand and North America. Most Didymo blooms reported occur either in lake-fed rivers or in regulated rivers (below dams), ie., generally stable flows.
Once a colony is established, fast currents are likely to enhance growth by promoting transfer of nutrients to the cells at the mat surface. It can flourish and choke riverbeds, gravels and abstraction intakes. It is said to be spread by anything wet or damp, particularly by anglers’ felt sole waders and unless completely dry for 2 days, survives out of water for up to one month - unless disinfected – using similar methods to that for GS (Kilroy 2004).
Initially discussed by Roberts (2007), concerns are now being expressed by fisheries in U.S.
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Snot Still Invading World's Rivers August 22nd, 2011 EARTHWEEK A slimy yellow-brown freshwater algae that once was native to only a few small stretches of rivers on Canada’s Vancouver Island has inexplicable begun to spread to new habitats around the world. Rock snot, or didymo, has now reached the waters of New Zealand, Iceland, Alberta and Atlantic Canada. Starting around 1990, it underwent large blooms that caused it to spread across Vancouver Island. In subsequent years, it started to spread around the world, according to aquatic invasive species expert Matthias Herborg. While it appears to be more of an aesthetic issue than a human health or wildlife problem, marine biologists are concerned it could alter food webs in rivers. When dried, didymo has the appearance of soiled toilet paper, causing some to think there’s a sewage problem in the river. "It greatly degrades the recreational experience," Herborg told Canadian Press. Experts believe it’s spread by recreational fishermen on the soles of their felt-bottom waders. At least one manufacturer has begun to phase them out, while some U.S. states have banned their use. Photo: Matapedia
headwater stream infested with Didymo. Recently Didymo has also
been found in New Brunswick's Tobique. |