Didymo

Important: Read the Following…….

Didymo (Didymosphenia geminata)

Didymo (Didymosphenia geminata)

Didymo (Didymosphenia geminata), also known as river or rock snot, has been found in a large number South Island rivers and lakes. A controlled area notice has been issued by Biosecurity NZ for the whole of the South Island. This means that people must properly clean any equipment that has been exposed to any river or lake water before leaving the South Island. Please also make sure that you Check, Clean or Dry equipment before moving between waterways within the South Island, to prevent the further spread of Didymo. For more information, click here.

Didymo is a member of the group of single-celled aquatic plants (freshwater algae) known as diatoms. It grows extensively over all the rocks in the river, excluding all other benign algal species which provide food for invertebrates on which fish feed. It makes fishing and other riverine activities more difficult and less pleasant, although it is not harmful to human health.  This is a serious threat to kayaking in New Zealand so please don’t take it lightly. A large proportion of rivers in the South Island are the ideal habitat for Didymo, as it prefers cool, clear, low nutrient rivers. Didymo can be transported in as little as a single drop of water so it is very important that any gear is properly cleaned and dried out thoroughly. If you spot any additional outbreaks of Didymo please call the MAF hotline on 0800 80 99 66.

After paddling any river, please try to do the following…..

  1. Check: Before leaving the river, remove all obvious clumps of algae and look for hidden clumps. Leave them at the affected site. If you find any later, do not wash them down drains. Treat them with the approved cleaning methods below, dry them and put them in a rubbish bin.
  2. Clean: Soak and scrub all items for at least one minute in either hot (60‹C) water, a two percent solution of household bleach or a five percent solution of salt, nappy cleaner, antiseptic hand cleaner or dish-washing detergent. A two percent solution is 200 ml, a five percent solution is 500 ml (two large cups), with water added to make 10 litres.
  3. Dry: If cleaning is not practical (i.e. livestock), after the item is completely dry to touch, wait an additional 48 hours before contact or use in any other waterway.

This procedure should be carried out before moving your boat to another river (to prevent contamination of other rivers) or moving it further up the river you are currently paddling (this reduces the risk of transporting Didymo upstream).

Leave a Reply