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STOP THE SPREAD
CHECK CLEAN DRY
The Waitahanui is the largest predominantly spring-fed river in the
region and has excellent water quality from its spring sources to
Lake Taupo. The spring fed nature of this river means that its bed is very stable with little flooding occurring and in its lower reaches contains significant charophyte meadows. These are important aquatic plants which can be threatened by introduced species. The river is likely also to have a high diversity of aquatic invertebrates which can also be threatened by pests.
Aquatic weeds are the greatest threat to the rivers indigenous values. In
the lower reaches a small amount of monkey musk, water cress and reed sweet grass are present on its margins, but otherwise the river is largely free of weeds.
With the discovery of Didymo in New Zealand Biosecurity New Zealand implemented the CHECK CLEAN DRY campaign to halt the spread of this freshwater alga. A stream like the Waitahanui could be very badly affected by invasive aquatic weeds if we don’t take care not to spread them.
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Listed below are answers to frequently asked questions about Didymo and CHECK CLEAN DRY;
1) WHERE DID DIDYMO COME FROM?
Didymo has existed in parts of North America, Europe and Northern Asia as a native for centuries so it is not new on the world scene. What is new is that the South Island of New Zealand is the only place that it has been positively identified in the southern hemisphere.
2) IS DIDYMO IN THE NORTH ISLAND?
The waterways of the North Island are tested on a regular basis. To date there has been no Didymo found in the North Island but the water test results are retrospective. The day to day status of the North Island is unknown.
3) ARE BIRDS SPREADING DIDYMO?
Although this may seem a logical way for Didymo to be spread there is no evidence that they are so the answer is no. The Nelson lakes area is a prime example. The Buller and Gowan rivers which are the outlets for Lakes Rotoroa and Rotoiti have been infected with Didymo for some years in yet the Sabine, Travis and D’Urville rivers which feed into the Lakes are negative. Further, although the spread of Didymo has been rapid through the South Island it would have been far faster had wildfowl been a transfer factor.
4) ISN’T TAUPO ONE CATCHMENT?
This is a question that is asked a lot and the answer is no. Each river is a separate catchment draining into Lake Taupo, which is the common catchment. For example, if an angler was to fish the Waitahanui river and then transfer to the Hinemaiaia stream then they are moving from one catchment to another and therefore we encourage them to CHECK CLEAN DRY. But if they were to fish the Waitahanui rip and then transfer to the Hinemaiaia mouth then they are still in the Lake and therefore the one catchment.
5) WHY CLEAN IF DIDYMO ISN’T HERE?
As stated in point 2 the day to day status of the North Island is unknown and therefore care needs to be taken. A further reason to CHECK CLEAN DRY is that Lakes Taupo and Rotoaira are positive to Hornwort but Lakes Otamangakau and Kuratau remain negative. Also, anyone familiar with the Waikato river system will appreciate the problems Lagrosiphon is causing. Add to this the threat of Alligator weed moving south from Northland and there are sufficient reasons to CHECK CLEAN DRY whether Didymo is here or not.
If moving between waterways there are good cleaning facilities and cleaning supplies at Windsor Lodge, and we are really grateful to Richard and Sandy for their support.
What you can do to help
Further information can be obtained from the following links
Or for a chat contact Didymo Dave on 027 240 9603
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