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Topic: Didymo latest update from bnz, Bioscurity update, please read....< Next Oldest | Next Newest >
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Steve Search for posts by this member.


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Joined: Jul. 2005
PostIcon Posted on: Oct. 05 2005,18:00   Ignore posts   QUOTE

Didymo Update
Ministry of Agriculture and Forestry
Te Manatu Ahuwhenua, Ngaherehere
ASB Bank House, 101-103 The Terrace, PO Box 2526, Wellington, New Zealand
Telephone: 64 4 474 4100 Facsimile: 64 4 474 4111 Web:
DATE 5 October 2005

Didymo delimiting survey well advanced, North Island testing to start.
Testing of North Island rivers for the presence of invasive Didymo algae should start on Friday.
The North Island testing plan is being finalised, but will prioritise nationally significant waterways including the high value rivers on the volcanic plateau and Waikato River. The survey is based on NIWA’s likely environments model which estimates the suitability of all New Zealand rivers for the establishment of Didymo, should it be introduced to the rivers.

The model shows 73 percent of rivers with the most suitable habitat for Didymo are in the South Island.

Meanwhile, testing continues in the South Island. Biosecurity New Zealand (BNZ) has divided the South Island into thirds, and testing in the northern third, which extends as far south as Kaikoura, is well advanced. Each third should take a week to complete, with the lower two-thirds tested in the next fortnight. The survey will also include Stewart Island.

Updates on any confirmed new finds will be issued the following week when results are available. In the meantime, the appropriate cleaning precautions should be taken on all rivers while BNZ continues to work to find where Didymo is present to help reduce the risk of spread, and to investigate control measures. Cleaning methods can be found on Biosecurity New Zealand’s website (

BNZ is committed to determining ways of managing Didymo, whether that is eradication, control, slowing the spread, or minimising the impacts and protecting high value areas.

Biosecurity New Zealand staff are being assisted in the testing programme by staff from NIWA, AgriQuality, the Department of Conservation, Fish and Game, and various regional and district council staff. River user groups continue to be hugely supportive and are working with BNZ to work out how cleaning methods can work best for their particular activity.

An extensive Didymo public awareness campaign is planned. To date, BNZ has sought to communicate to river users through stakeholder organisations like national river recreation aassociations, regional councils, Fish and Game, Maritime New Zealand and the Department of Conservation and will continue to do so. Media reporting has done much to spread the word.
In coming days, updated information will be handed out on Interisland ferries and an advertising campaign will begin. The shape of this campaign is still being finalised. Public meetings are planned in Murchison tomorrow night (6 October) at 7pm at the Murchison Bowling Club, and the Wanaka Community Centre at 7pm on Monday 10 October.

At this stage, Didymo has been confirmed in Southland’s Waiau, Oreti and Mararoa Rivers, the Upper Clutha and Hawea River in Otago and the Buller River in the Tasman District. However, all rivers should be treated as suspect and the appropriate cleaning methods used while BNZ establishes where Didymo is.

Biosecurity Controlled Areas remain in force in Southland, Buller and Hawea. These will be reviewed at the end of the delimiting survey. No further Controlled Areas are planned in the meantime.

Biosecurity New Zealand notes the following:

• Recent Didymo finds do not indicate rapid spread, but rapid detection of Didymo. Didymo is a microscopic organism, often difficult to detect, which is now blooming, making it more visible.

• Didymo is present in numerous Northern Hemisphere countries. No control or eradication methods to rid Didymo from waterways have been developed. Aqua-Gel, as proposed earlier this week by others, is not a solution. It works on multi celled plants in still water such as lakes and ponds, but has not been shown effective in controlling single celled algae on the bottoms of flowing rivers.

• Finding a solution involves finding control methods that do not create a greater environmental problem.

• There is a lack of scientific information about Didymo. Due to the research completed since the Southland incursion was first confirmed in October 2004, New Zealand has become a world expert on this organism.

• It is likely that recent finds pre-date the initial Southland incursion and are only coming to notice now as blooms form.

• To ensure you do not spread Didymo, wherever possible use equipment, boats, clothing and other items for exclusive use in a single waterway.

If you are moving items between waterways you must -

1. Inspect: 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 dishwashing 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 the above 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.

Edited by Steve on Oct. 05 2005,18:19

Steve Gerard
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