Didymo

Didymo (Didymosphenia geminata), also called Rock Snot, is a freshwater alga that is widespread in the Northern Hemisphere. Although not present in Australia, it is considered a significant pest, being highly invasive, and is prohibited from entry to Tasmania.

Didymo (Didymosphenia geminata), also called Rock Snot, is a freshwater alga that is widespread in the Northern Hemisphere. Although not present in Australia, it is considered a significant pest, being highly invasive, and is prohibited from entry to Tasmania.

Didymo is made up of microscopic diatom (type of alga) cells. It takes just one cell in a single drop of water to be spread between waterways. The cells attach to rocks and submerged plants, multiplying quickly to form massive blooms that completely smother the stream or lake bed. These algal clumps adversely affect water quality, aquatic invertebrates and fish stocks, and are a hazard for hydro generation, irrigation and recreation.

Didymo was recently discovered in New Zealand, where it has invaded a number of waterways in the South Island and is causing a major concern for fisheries managers and anglers. It poses a significant threat in Tasmania because of the potential transfer from NZ via used fishing and other equipment. Wet or damp fishing gear, particularly felt-soled boots, has been identified as a primary vector for transferring the alga but anything that has the potential to hold contaminated water droplets is a concern.

The Keep Out Didymo brochure (pdf) and other publications relating to Didymo are available below.

Didymo Publications

 Title   Date   Size 
File Didymo Brochure Feb 12, 2008 483.3 kB