Species Information


VT DEC

VT DEC
Didymo (a.k.a. rock snot)
Didymosphenia geminata

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History
  • There are a few North American records dating back to the late 1800's
  • First modern documentations in northeastern North America in Quebec, 2006
  • First nuisance blooms in northeastern North America documented in Batten Kill, NY, 2006; several rivers in Quebec and New Brunswick, 2007; and Connecticut River drainage of NH and VT, 2007
  • Nuisance blooms have occurred in several additional rivers and streams in the northeast in subsequent years

Characteristics
  • Tan, light brown or brown clumps or ropy strands
  • Feels rough, cottony or fibrous; does not feel slimy to the touch
  • Can form thick solid mats (1-4 inches) on rocks or stream bottoms, or may appear clumpy or feathery
  • Dried stalk material on shore may look like dried cardboard or toilet tissue
  • Definitive identification requires microscopic examination

Habitat
  • Clear, swift-flowing rivers and streams with rocky bottoms
  • Often found in tailwaters below dams
  • Occasionally found in large lakes with continuous wave action

Known Distribution in the Northeast
  • Various rivers and streams in Quebec, New Brunswick, VT, NH, NY and CT

Impacts
  • Alters the composition of aquatic insect communities in areas of heavy infestation
  • Degrades aesthetic quality of pristine streams
  • Heavy infestations may impact infrastructure such as clogging irrigation intake pipes
  • Although no direct impacts on fish communities have been documented, there is concern about potential long term impacts


NH DES
400x Magnification
VT DEC