Didymosphenia geminata

Summary 3

First described from northern Europe, this pennate diatom is also known as 'rock snot' (and 'didymo'). It is an invasive species within America, creating thick layers on the bottoms of lakes and slow moving streams, inhibiting effective oxygen supplies, and leading to the distress and death in the benthos. The algae, didymo, is in Yukon, but we don’t have a good understanding of where it’s found and whether it’s spreading. Didymo is considered invasive elsewhere, but may in fact be native to Yukon.

Environment Yukon

Identification 4

Looks like: Range in colour from brownish-yellow to white, in clumps or ropes
Feels like: Rough texture like wet cotton wool when pulled apart
Found: In clumps on rocks or plants, or floating in the current

Not Didymo
Looks like: Green or dark brown/black, transparent
Feels like: Slimy texture, falls apart when handled
Found: Attached to the bottom with roots

Environment Yukon

Native range 5

The native distribution of D. geminata is the cool temperate regions of the Northern Hemisphere, including the rivers of northern forests and alpine regions of Europe, Asia and parts of North America. Until its recent discovery in New Zealand, where it was introduced, it was never previously found in the Southern Hemisphere. The distribution of didymo in the last two decades appears to be gradually expanding outside its native range. Even within its native range, there have been reports of excessive growths in areas where it previously existed only in low concentrations.

Sources and Credits

  1. (c) L.G. Johanson, some rights reserved (CC BY-NC), http://inaturalist.ca/photos/8127247
  2. (c) Malcolm Storey, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/22829530
  3. Adapted by L.G. Johanson from a work by (c) Unknown, some rights reserved (CC BY), http://eol.org/data_objects/18361252
  4. (c) L.G. Johanson, some rights reserved (CC BY-SA)
  5. Adapted by L.G. Johanson from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Didymosphenia_geminata

More Info

iNatCA Map

Color brown, white
Algae Diatoms (Bacillariophyceae)