Check, clean and dry around water this summer

Imagine a thick layer of brown snotty material covering the rocks at your favourite river swimming hole or your fishing line being weighed down by a mass of snot like material at your favourite fly-fishing spot. That’s what could happen if the freshwater algae didymo arrives in the Wellington region and becomes established in our rivers, says Richard Grimmett, Senior Biosecurity Officer at Greater Wellington Regional Council.

“Didymo is already fouling many of the South Island’s iconic rivers and it will only be vigilance on the part of all water users that will stop the same thing happening here.”

Didymo has not been found in the North Island.

Didymo, also known as rock-snot, can form massive blooms on the bottom of streams, rivers and lakes. It attaches itself to the streambed by stalks, and can form a thick brown layer that smothers rocks, submerged plants and other material. It often forms long flowing ‘rats tails’ that can break off and flow downstream looking and feeling similar to toilet paper.

Mr Grimmett says the tiniest piece of didymo has the potential to grow and spread to foul an entire river system.

“It’s a microscopic pest that becomes a monster. It can be spread by a single drop of water. Even if you can’t see it, you could be spreading it.”

“Much will rely on people using South Island rivers following the check, clean, dry message before travelling to the North Island. However, the really worrying aspect, is that it could already be in the North Island, but is yet to be detected.”

“With that in mind the best way to protect our waterways from this pest and others is to pretend that they are already here and adopt a simple practice to stop them from spreading.”

Mr Grimmett says the way to stop spreading aquatic weeds like didymo is to check, clean and dry all your gear after leaving the water and before you enter again.

“Check all your gear for traces of aquatic weeds when you leave a waterway and before you enter another one. Gear can be a boat, boat trailer, boots, fishing gear, nets or anything else that you take into the water. Check it, clean it and dry it, before you enter another waterway.”

Greater Wellington have contracted two staff over summer to spread the check, clean and dry message to people who use waterways across the Wellington region.

They will be visiting popular river spots around the region talking to all they meet about how to prevent spreading aquatic weeds. They will be delivering awareness material around clubs and retailers and putting up signs at popular swimming and boating spots.

Greater Wellington monitor water samples for didymo from the Tauherenikau, Waiohine, Waingawa, Ruamahanga, Hutt, Orongorongo, Waikanae and Otaki rivers. Water monitoring staff keep a watchful eye for any telltale signs when working in waterways throughout the region.

For general information on didymo visit www.biosecurity.govt.nz