Didymo

Gisborne district is free from Didymosphenia geminata, common name didymo or rock snot, and we need to keep it that way.

Didymo is an invasive freshwater alga that grows in rivers, streams and lakes.  Didymo continues to devastate many rivers in the South Island, where it favours cold, clear, shallow running water. 

Didymo can be spread by just one microscopic algal cell in a single drop of water.  Even if you cannot see it you could easily spread it.  It's believed didymo has not yet reached the North Island, but if it does it could cause significant damage to fresh water native fish, trout, plants and insects in our region.  It makes rivers, streams and lakes unsightly and most unpleasant for swimming, boating and fishing.  We all need to be extremely careful when going from one waterway to another.  People are legally obliged to prevent the spreading of didymo.

The 'Check Clean Dry' method to contain didymo

The 'check clean dry' method has been adopted as a means to prevent didymo infecting Gisborne's waterways.

When leaving a waterway ‘check’ for and remove any visible clumps from gear and leave these at the site or in a rubbish bin.
‘Clean’ your gear.  For recommended cleaning methods visit Biosecurity NZ website.
If items are not cleaned, they need to be completely ‘dry’ to touch for at least 48 hours before entering another waterway.

Recommended cleaning methods for specific activities such as farm animals, pets, gravel extraction material etc

If you suspect you've sighted any didymo phone MAFs hotline: 0800 80 99 66.

Helping get the message across

The responsibility of making people using Gisborne district waterways more aware of didymo has been made a student summer job. The job is a public relations role, travelling to far corners of the district, working with people at popular rivers and waterways.

The student didymo advocate job has so far been hugely successful and we hope to see more good work in the future.

Didymo can form large mats on the bottom of lakes, rivers and streams which have smothering effects on rocks, submerged plants and other materials. This can affect stream habitats and sources of food for fish and make recreational activities like kayaking, fishing, boating and swimming unpleasant.

Didymo is native to temperate Northern Hemisphere areas. Until didymo was found in the lower Waiau River of the South Island in 2004 it had not previously entered the Southern Hemisphere.