Didymo in New Zealand
Encyclopedia
In 2004 Didymosphenia geminata
, a diatom
commonly known as didymo or rock snot, was discovered in New Zealand
, the first time it was found in the southern hemisphere. To restrict its spread, the whole of the South Island
of New Zealand was declared a controlled area in December 2005. All items, such as boats, fishing gear, clothing, and vehicles, that have been in a stream, river or lake, must be cleaned before they enter another waterway. Biosecurity New Zealand working with Environment Southland, AgriQuality and Fish and Game
launched an extensive public awareness campaign to encourage river users to clean their equipment after use in affected waterways. This campaign was highly successful, with 99% of freshwater users surveyed in 2008 in the South Island being aware of didymo.
in Southland
. The National Institute of Water and Atmospheric Research
identified the algae as Didymosphenia geminata and confirmed that it is New Zealand's first documented detection.
In October 2005, populations of didymo were discovered in the Hawea
, Buller
, Oreti
and Upper Clutha
rivers. Delimiting testing is being undertaken in North Island waterways and other South Island river systems to find out how far didymo has spread in New Zealand.
In October 2007, dead didymo cells were found in routine water samples from the Whanganui
, Tongariro
, Whakapapa
rivers, and the Mangatepopo Stream in the central North Island, with MAF
suspecting further contamination.
In October 2009, didymo was detected in the Upper Rangitata River
in Canterbury. The Upper Rangitata River is known as one of the most important braided river habitats for the endangered Black-fronted Tern
, the Wrybill
and the endangered upland Longjawed galaxias
.
In February 2010, didymo was detected in the Waimakariri River
.
In May 2010, didymo was detected in the Riwaka River
, the Pearse River and the Maruia River in the Nelson-Tasman region in the top of the South Island.
Check: Before leaving the river, remove all obvious clumps of algae and look for hidden clumps. Leave them at the site. If you find clumps later don't wash them down the drain, treat them with the approved methods below, dry them and put them in a rubbish bin.
Clean: Soak and scrub all items for at least one minute in either hot (60°C) water, a 2% solution of household bleach or a 5% solution of salt, antiseptic hand cleaner or dishwashing detergent.
Dry: If cleaning is not practical (e.g. livestock, pets), after the item is completely dry wait an additional 48 hours before contact or use in any other waterway.
Didymosphenia geminata
Didymosphenia geminata, commonly known as didymo or rock snot, is a species of diatom that grows in warm and shallow water. If it overgrows, it can form large mats on the bottom of lakes, rivers and streams. It is not considered a significant human health risk, but it can affect stream habitats and...
, a diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
commonly known as didymo or rock snot, was discovered in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, the first time it was found in the southern hemisphere. To restrict its spread, the whole of the South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
of New Zealand was declared a controlled area in December 2005. All items, such as boats, fishing gear, clothing, and vehicles, that have been in a stream, river or lake, must be cleaned before they enter another waterway. Biosecurity New Zealand working with Environment Southland, AgriQuality and Fish and Game
Fish and Game New Zealand
Fish and Game New Zealand is a statutory body set up to advocate for recreational hunting and fishing in New Zealand.It was set up under the Conservation Act 1987 with the statutory responsibility for the sports of freshwater sport fishing and gamebird hunting...
launched an extensive public awareness campaign to encourage river users to clean their equipment after use in affected waterways. This campaign was highly successful, with 99% of freshwater users surveyed in 2008 in the South Island being aware of didymo.
Spread
In October 2004, an unusual algal growth was found in the lower Waiau RiverWaiau River, Southland
Waiau River is the largest river in the Southland Region of New Zealand. It is the outflow of Lake Te Anau, flowing from it into Lake Manapouri 10 kilometres to the south, and from there flows south for 70 kilometres before reaching the Foveaux Strait eight kilometres south of Tuatapere...
in Southland
Southland Region
Southland is New Zealand's southernmost region and is also a district within that region. It consists mainly of the southwestern portion of the South Island and Stewart Island / Rakiura...
. The National Institute of Water and Atmospheric Research
National Institute of Water and Atmospheric Research
The National Institute of Water and Atmospheric Research or NIWA , is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts commercial and non-commercial research across a broad range of disciplines in the environmental sciences...
identified the algae as Didymosphenia geminata and confirmed that it is New Zealand's first documented detection.
In October 2005, populations of didymo were discovered in the Hawea
Hawea River
The Hawea River is a river of New Zealand, draining Lake Hawea into the Clutha River.-References:...
, Buller
Buller River
The Buller River is in the South Island of New Zealand. One of the country's longest rivers, it flows for 170 kilometres from Lake Rotoiti through the Buller Gorge and into the Tasman Sea near the town of Westport...
, Oreti
Oreti River
The Oreti River is one of the main rivers of Southland, New Zealand, and is 170 kilometres in length.The Oreti has its headwaters close to the Mavora Lakes between Lake Te Anau and Lake Wakatipu, and flows south across the Southland Plains to its outflow into Foveaux Strait at the southeastern end...
and Upper Clutha
Clutha River
The Clutha River / Mata-Au is the second longest river in New Zealand flowing south-southeast through Central and South Otago from Lake Wanaka in the Southern Alps to the Pacific Ocean, south west of Dunedin. It is the highest volume river in New Zealand, and the swiftest, with a catchment of ,...
rivers. Delimiting testing is being undertaken in North Island waterways and other South Island river systems to find out how far didymo has spread in New Zealand.
In October 2007, dead didymo cells were found in routine water samples from the Whanganui
Whanganui River
The Whanganui River is a major river in the North Island of New Zealand.Known for many years as the Wanganui River, the river's name reverted to Whanganui in 1991, according with the wishes of local iwi. Part of the reason was also to avoid confusion with the Wanganui River in the South Island...
, Tongariro
Tongariro River
The Tongariro River is a river in the North Island of New Zealand. It originates in the Central Plateau of the North Island where it is fed by numerous Tributaries that flow off the surrounding hill ranges and mountains such as Mount Ruapehu...
, Whakapapa
Whakapapa River
The Whakapapa River in New Zealand trickles off the Whakapapa skifield of Mount Ruapehu, down the western slopes of the mountain through Owhango before finally merging with the Whanganui River just east of Kakahi at ....
rivers, and the Mangatepopo Stream in the central North Island, with MAF
Ministry of Agriculture and Forestry (New Zealand)
The Ministry of Agriculture and Forestry is the state sector organisation of New Zealand which deals with matters relating to agriculture, forestry and biosecurity...
suspecting further contamination.
In October 2009, didymo was detected in the Upper Rangitata River
Rangitata River
The Rangitata River is one of the braided rivers that helped form the Canterbury Plains in southern New Zealand. It flows southeast for 120 kilometres from the Southern Alps, entering the Pacific Ocean 30 kilometres northeast of Timaru...
in Canterbury. The Upper Rangitata River is known as one of the most important braided river habitats for the endangered Black-fronted Tern
Black-fronted Tern
The Black-fronted Tern also known as Sea Martin, Ploughboy, Inland Tern, Riverbed Tern or Tarapiroe, is a small tern generally found in or near bodies of fresh water in New Zealand and forages for freshwater fish, arthropods and worms. It has a predominantly grey plumage...
, the Wrybill
Wrybill
The Wrybill or Ngutuparore Anarhynchus frontalis is a species of plover endemic to New Zealand. It is unique in that it is the only species of bird in the world with a beak that is bent sideways ....
and the endangered upland Longjawed galaxias
Longjawed galaxias
The longjawed galaxias, Galaxias prognathus, is a galaxiid of the genus Galaxias, found only in rivers and streams at mid to high altitudes on the eastern side of the Southern Alps in the South Island of New Zealand...
.
In February 2010, didymo was detected in the Waimakariri River
Waimakariri River
The Waimakariri River is the largest of the North Canterbury rivers, in the South Island of New Zealand. It flows for 151 kilometres in a generally southeastward direction from the Southern Alps across the Canterbury Plains to the Pacific Ocean....
.
In May 2010, didymo was detected in the Riwaka River
Riwaka River
The Riwaka River is located in the Nelson region in the northwest of New Zealand's South Island. It flows for 20 kilometres, entering Tasman Bay close to the town of Riwaka, 10 kilometres north of Motueka....
, the Pearse River and the Maruia River in the Nelson-Tasman region in the top of the South Island.
Preventing the spread
The following methods are recommended by MAF Biosecurity New Zealand to prevent the spread of didymo in New Zealand:Check: Before leaving the river, remove all obvious clumps of algae and look for hidden clumps. Leave them at the site. If you find clumps later don't wash them down the drain, treat them with the approved methods below, dry them and put them in a rubbish bin.
Clean: Soak and scrub all items for at least one minute in either hot (60°C) water, a 2% solution of household bleach or a 5% solution of salt, antiseptic hand cleaner or dishwashing detergent.
Dry: If cleaning is not practical (e.g. livestock, pets), after the item is completely dry wait an additional 48 hours before contact or use in any other waterway.
External links
- Didymo page at Biosecurity New Zealand
- Didymo page at the Department of Conservation