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Didymo - what is it and how can you help?
Didymo (Didymosphenia geminata) is a freshwater diatom (algae) that can cause massive algal blooms on the beds of streams, rivers and occasionally lake edges where wave action exists. Didymo has recently been identified in the South Island of New Zealand and consequently the potential for translocation to Tasmania is vastly increased. Didymo can adversely affect freshwater fish, plant and invertebrate species by reducing the number of suitable habitats available to these species.
Didymo Pest Case
Didymo (Didymosphenia geminata), commonly 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 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 Government is working to prevent the introduction of Rock Snot to Australia at Quarantine entry points. Anglers who are visiting Australia or returning home from a fishing trip overseas, are now required to declare all used fishing equipment for inspection. Any potentially contaminated fishing or other freshwater recreational equipment will be confiscated and treated by Quarantine staff.
Help to Keep Out Didymo
If you are a visiting angler or a local travelling overseas to fish
- Don’t bring used fishing gear, particularly anything damp or wet including boots, waders, flies, nets and clothing into Tasmania.
- Hire, buy or borrow your fishing gear locally when travelling overseas.
- If you do bring your own gear, Check Clean Dry it before you arrive in Tasmania and use the latest recommended treatment methods.
- Declare all fishing equipment upon entry to Australia.
- Develop the ‘Check Clean Dry’ practice for all your fishing equipment, including camping gear, boat and trailer when moving between waters within the State.
Check Clean Dry your fishing gear
- Check your gear before leaving the waterway and remove visible clumps of algae. Material removed later should be cleaned, dried and disposed of in a rubbish bin.
- Clean your gear by soaking in a hot water solution of 5% household bleach or washing detergent for 45 minutes. Discharge cleaning waste away from waterways.
- If cleaning is not practical, dry your gear completely and wait an additional 48 hours* before contact or use in another waterway. *Felt-soled boots need much longer.
Report any suspicious algal sightings in Tasmanian waterways
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Didymo can be distinguished from native species of algae by:
- Colour - Didymo is beige/brown/white but not green.
- Touch - Although it looks slimy, it doesn't feel slimy, but rather spongy and scratchy like cotton wool.
- Odour - Live Didymo has no distinctive odour.
- Strength - Didymo is very securely attached to river stones and does not fall apart when rubbed between your fingers.
- Microscope - Definitive identification requires microscopic analysis/
Be informed and know the latest research findings
Contact: Sarah Graham ph 6261 8075
Visit:
www.biosecurity.govt.nz/didymo
