Summer didymo awareness drive in Marlborough and Nelson

Date:  18 December 2006

Rangers are out and about this summer spreading the word to Nelson and Marlborough river users about preventing the spread of the invasive alga didymo.

The three rangers, in Department of Conservation uniforms, are reminding boaties, kayakers, anglers and others recreating on rivers to ‘check, clean, dry’ their gear to avoid spreading didymo to unaffected waterways. The rangers are handing out small bottles of detergent for cleaning gear and offering to help clean the equipment of anyone who might be likely to spread didymo. 

The didymo awareness initiative has been jointly set up by the Marlborough and Tasman District Councils, Nelson-Marlborough Fish and Game and the Department of Conservation. The councils applied for and received Biosecurity New Zealand funding for the scheme and DOC’s St Arnaud office is running it.

DOC St Arnaud biodiversity programme manager Brian Paton said didymo was only known to be in the Buller and Gowan Rivers in the Nelson-Marlborough region and the agencies involved were taking action in a bid to keep it out of other rivers.

Follow these steps to help prevent the
spread of didymo

“It’s important that we keep didymo out of rivers in Nelson and Marlborough that haven’t been infested with it, including the Motueka, Wairau and Clarence rivers and unaffected tributaries of the Buller, such as the Matakitaki, Owen and Matiri rivers.

“With increased recreation activity on rivers over summer, it is a critical time to get out and talk to river users to make sure they are aware of the ‘clean, check, dry’ cleaning procedures and that they are using them.  

“As well as alerting river users to didymo, the rangers are making them aware of other aquatic pests, such as the pest fish gambusia and koi carp, and waterweeds such as hornwort and lagarosiphon.

“We are urging everyone recreating in rivers and other water bodies to use the ‘check, clean, dry’ procedures. It is essential to halt the spread of didymo and it will also protect our waterways from other aquatic pests. We need everybody to do their bit to keep our waterways beautiful.”

‘Check, clean, dry’ procedures should be applied to all items that have contact with the water including boats, clothing, gumboots and fishing gear. Biosecurity New Zealand advises that wherever possible equipment should be restricted to exclusive use in a single waterway.

Fish and Game is also advising anglers not to wear felt soled boots as it appears to be virtually impossible to effectively decontaminate felt soled boots or waders. Anglers are advised to use a rubber alternative that will dry rapidly and is easily cleaned.

The ‘check, clean, dry’ procedures are:

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, dry them and put them in a rubbish bin.

Clean: Soak and scrub all items for at least one minute in either hot (60oC) water, a two percent solution of household bleach or a five percent solution of salt, nappy cleaner, antiseptic hand cleaner or dishwashing detergent. A two percent solution is 200ml, a five percent solution is 500ml (two large cups), with water added to make 10 litres.

Dry: If cleaning is not practical, after the item is completely dry to touch, wait an additional 48 hours before contact or use in any other waterway.

Didymo can form massive blooms. Thick growths can adversely affect freshwater fish, including whitebait species, plant and invertebrate species by reducing the number of suitable habitats.

Didymo is made up of microscopic cells that cannot be seen with the naked eye and can be spread by a single drop of water.