Didymosphenia geminata



Legal Status: Unwanted Organism - MPI
Status in New Zealand: Investigating
Organism: Marine and freshwater plants

Since 2008 MAF has lead the Didymo Long-Term Management Programme in partnership with Fish and Game New Zealand , Department of Conservation , Iwi, impacted industry and regional councils. These partners continue to play a significant role in delivery of the programme.

The North Island remains free of didymo, and the rate of spread throughout the South Island has significantly slowed. Based on sampling results didymo has established in over 150 waterways in the South Island.

Over the 2010/11 summer period, advocates from MAF and partner organisations continued to visit lakesides, rivers and sporting events to educate freshwater users and distribute collateral.

Research to evaluate the effectiveness of the 2009-2010 CCD programme indicated that 96% of respondents take at least one action to Check, Clean, Dry, and 22% of respondents CCD equipment between waterways more often.

June 2008 - Didymo is transitioned from a response phase into a long term management programme. Regional partner organisations play a significant role in the long term management of didymo.

February/March 2008 - The intensified summer social marketing programme concluded for the summer.

January 2008 – Reports finalised from the National Delimiting Survey, and entered into the Didymo Samples Database.

November 2007 – MAFBNZ undertakes additional research on Gemex™ control tool. NIWA, Diffuse Sources Ltd, Fish and Game Southland and Cawthron Institute, were contracted to complete this research.

The final National Delimiting Survey commenced in November with regions from all over New Zealand sampling rivers. Future delimiting surveys will be conducted on a regional basis.

Didymo advocates recruited for an intensified programme to raise the awareness of didymo over the summer period.

October 2007 – Dead didymo cells found in the Tongariro River in Taupo on Wednesday 31 October. MAFBNZ worked with partners to manage the situation. The dead cells that were found were tracked back to cross contamination from a laboratory in the South Island.

September 2007 - MAFBNZ decides to undertake further research into the use of chelated copper as a potential emergency response control tool for didymo under certain conditions.

The Didymo Samples Database went live and partner organisations were provided with training and login details. All organisations involved in sampling now use the database to record their results.

July 2007 - The didymo science seminar was held on the 24th July and was attended by 100 people. The seminar provided an overview of findings from the 2006-07 didymo science and technical programme.

July 2007 - The didymo long-term management (LTM) programme came into operation on the 1st July. The programme was developed by a partnership including MAFBNZ, Department of Conservation, Fish and Game New Zealand, regional councils, affected industry and specific Maori entities. It outlines objectives, roles and responsibilities for the ongoing management of didymo.

June 2007 - Government approves $13.3 million over the next four years for both MAF Biosecurity New Zealand and the Department of Conservation to implement and participate as a partner in the Long-term management programme for didymo.

May 2007 - A North Island didymo detection simulation was run in the Taupo region on Thursday 31st May.

May 2007 - The controlled area around Monowai River was lifted. The Controlled Area was put in place for the early stages of potential control tool research, and was lifted when no longer necessary.

April/May 2007 - Biosecurity New Zealand staff coordinated a series of meetings around the country resulting in the formation of 11 regional groups. These groups will implement the long-term management programme in the regions.

February 2007 - Environmental trials of potential didymo control tool in Princhester Creek in Southland begin. The trials of a chelated copper formulation were conducted by NIWA under contract to Biosecurity New Zealand.

July/August 2006 – Delivery of 2005-2006 Didymo Research Reports. Planning of the 2006-07 research programme begins.

12 May 2006 – Distribution of multi-lingual cleaning cards for tourists

19 April 2006 – 2,000 factsheets distributed during Coast-to-Coast promotion tour of North Island

17 March 2006 – Public awareness survey finalised.

9 March 2006 – Economic Impact Assessment finalised

March 2006 – Distributed 37,000 factsheets to hunters

21 February 2006 -Didymo found in the Ahuriri River in Canterbury

February 2006 – Cleaning DVD developed and distributed to:

  • Regional Councils
  • Department of Conservation Regional offices
  • Fish and Game Regional offices
  • Ferries

31 January 2006 – Stakeholders meeting chaired by Environment Canterbury held in Christchurch

January 2006 – Organism Impact Assessment completed

19 December 2005 – NIWA October delimiting survey report published

December 2005 – South Island Controlled area becomes effective. Regional controlled areas and permit systems lifted.

Science research work continues with environmental control trials commencing in Southland.

29 November 2005 – Didymo confirmed in Lake Manapouri and increased biomass noted in the Upper Waiau.

8 November 2005 – Third Technical Advisory Group held.

November 2005 – Interim national didymo strategy confirmed. This includes a South Island didymo controlled area plus a public awareness campaign.

The public awareness campaign is boosted over the summer period radio and print advertising, and also internet advertising on the XtraMSN Weather and news, Metservice and Smile City sites.

200,000 information packs distributed to:

  • 66,000 Fish and Game license holders
  • Fish and game license issuing agents
  • Department of Conservation concession holders
  • 11,000 multisport database
  • Regional Councils
  • Biosecurity New Zealand stakeholder database
  • Freshwater clubs (kayaking, 4WD etc)
  • MAF Quarantine Service
  • Fish and Game Regional offices
  • Department of Conservation Regional offices
  • Schools
  • Helicopter companies
  • Ferries

Posters distributed to:

  • Fish and game license issuing agents
  • Fish and Game Regional offices
  • Department of Conservation Regional offices
  • Regional Councils
  • Ferries

7 October 2005 – Delimiting survey begins in the central North Island. Samples from the Northern and Central third of the South Island show no evidence of Didymo other than the initial confirmed find in the mainstem of the Buller River.

3 October 2005 – Nationwide delimiting survey begins, starting with the Northern third of the South Island. The survey is guided by the preferred habitat model and information from a variety of sources about high-use and high-value rivers, and specific high risk sites.

1 October 2005 – Start of freshwater sport fishing season. Controlled Area Notices on Buller River and Hawea River become effective. Radio and newspaper advertising advise people of these, and 40,000 factsheets are distributed in the area. River patrols are continued.

30 September 2005 – Didymo confirmed in the upper Waiau and Oreti in Southland.

'Check, Clean, Dry' public awareness campaign expanded nationally. This includes significant radio and newspaper advertising and media coverage as well as distribution of information.

29 September 2005 – Didymo confirmed in the Hawea River in Central Otago.

Decision made to place Controlled Areas on the Buller and Hawea. Decision on the declaration of further Controlled Areas to be made at the conclusion of the nationwide delimiting survey.

28 September 2005 – Didymo confirmed in the Buller River in the Tasman District.

September 2005 – NIWA publishes report on the likely New Zealand freshwaters that Didymo could establish in.

19 August 2005 – Southland didymo Controlled Area becomes effective

August 2005 – Information evening for whitebaiters in Invercargill, Tuatapere and Te Anau just before the start of the whitebait season.

16 June 2005: Didymosphenia geminata officially listed as a global invasive species by The Invasive Species Specialist Group, a global group of 146 scientific and policy experts on invasive species from 41 countries, for inclusion in the Global Invasive Species Database.

June 2005 Cabinet grants $835,000 to strengthen containment measures and further research on didymo's distribution, impacts and potential control and eradication methods.

Second TAG held to discuss outcomes of the delimiting surveys, decontamination trials, the results of the potential distribution modelling, the public awareness campaign and for preliminary discussions on potential methods for controlling Didymo on a larger scale – beyond items that have simply been in contact with Didymo affected water).

TAG advises that distribution must be confirmed before attempting control or eradication actions - should any feasible methods be identified. Further surveillance is planned for the South Island for September/October 2005 as this is the best time to detect Didymo blooms.

12 May 2005 Fish and Game, Department of Conservation and Environment Southland meet to determine the best way to strengthen containment in Mararoa and lower Waiau.

May 2005 – Duckshooting season. Specific public awareness activity via media releases and paid advertising, and river patrols in the Southland region.

Ecological research initiated to:

  • investigate factors (e.g. light, water flow, water chemistry etc) that may contribute to Didymo blooms
  • monitor changes in Didymo blooms in relation to these factors
  • investigate impact of Didymo blooms on river invertebrates and potential impacts on the food chain.

April 2005 – Initiation of Cabinet paper seeking additional resources to strengthen containment measures and collect additional information on Didymo distribution, impacts and potential control and eradication methods.

March 2005 – Research to determine rivers in New Zealand where Didymo is most likely to establish. Work also done to understand the perceived environmental, cultural, social and economic impacts of didymo – this will be included in Economic Impact Assessments and Organism Impact Assessments.

24 February 2005 – Response update presented to Zone 6 meeting of Local Government New Zealand in Dunedin (attended by mayors, councillors, and regional, district and city councils from Southern South Island).

22-23 February 2005 – Didymo information evenings held in Invercargill, Tuatapere and Te Anau.

4 February 2005: MAF Biosecurity New Zealand initiates the inclusion of Didymosphenia geminata in the Global Invasive Species Database.

January 2005 – A fisherman reveals that he believes he spotted Didymo blooms on the Mararoa River in late 2001. He was an overseas angler familiar with Didymo who fished the river every year from 1998. This is considered to be a credible sighting, and is supported by subsequent similar reports.

December 2004/January 2005 – Extensive efforts to promote avoidance of the affected Southland rivers. This includes Environment Southland, Fish and Game and Agriquality staff patrolling the rivers, and provision of a vehicle to help with gear cleaning over the height of the season.

17 December 2004 – Delimiting survey conducted to investigate the presence or absence of microscopic Didymo in Southland rivers. There are no positive results.

18 December 2004 – Official confirmation from a United States expert confirming the NIWA Didymosphenia geminata identification.

14 December 2004 – Information evening held in Te Anau

10 December 2004 – TAG meets in Te Anau to discuss Didymo and immediate response priorities.

While advising that it was likely that Didymo would be present in other rivers (at least in its microscopic form), the TAG recommended that BNZ:

  • Attempt to contain Didymo to the known affected rivers
  • Assess treatment methods for equipment used in rivers
  • Conduct further surveys of surrounding rivers to see if Didymo is being present in its microscopic form
  • Determine the extent of at-risk river habitat in New Zealand.

9 December 2004 – Technical Advisory Group (TAG) formed to provide independent scientific advice to BNZ about pest organisms visits the affected rivers. The Didymo TAG is made up of scientists from the Department of Conservation, the National Institute of Water and Atmospheric Research (NIWA), and scientists from the United States and Canada. Also attending the meeting are representatives from BNZ, Environment Southland, Fish and Game and Meridian Energy.

8 December 2004 – Signs on affected rivers ask people to avoid using them. Subsequent reports from personnel patrolling the rivers Fish and Game, AgriQuality, Department of Conservation and confirm 80-90% compliance. Those found using the river are cleaning their gear.

December 2004 – Having finalised a report on the biology, distribution, effects and potential risk for New Zealand freshwaters the previous month, NIWA develops cleaning methods which will kill Didymo on aquatic equipment. This allows rivers to be used while managing the risk, and are scientifically proven to be effective.

Biosecurity New Zealand reviews containment options (education versus regulatory) Public awareness is identified as the most appropriate approach because:

  • Eradication or control was not likely in the short term
  • Expert advice is that didymo is likely to be present outside of the known affected waterways
  • Restricting access would not address the risk from birds and other animals
  • Appropriate cleaning methods for river equipment had been developed
  • More likelihood of community buy-in through an inclusive rather than a regulatory approach
  • Awareness material also highlights the responsibility of all river users to take this approach – regardless of which rivers are being used. This material is distributed to regional councils, research institutes, Department of Conservation consent holders on the Mararoa and Waiau rivers, Information centres, local recreation clubs, all South Island schools, and the MAF Quarantine service, for distribution to incoming travellers.

November 2004 - NIWA finalises report on the biology, distribution, effects and potential risk for New Zealand fresh waters. The report is primarily based on what little information is available internationally – much of which is anecdotal.

17 November 2004 Didymo is declared an unwanted organism under the Biosecurity Act 1993, allowing the use of powers under the Act.

In agreement with key stakeholders Environment Southland, Otago Regional Council, Department of Conservation, Fish and Game, NIWA, Te Ao Marama and Meridian Energy, the initial response objectives are to minimise further spread, obtain information on Didymo distribution and likely impacts in New Zealand, and obtain information on potential long-term management options.

A public awareness strategy is developed. A didymo webpage is published on the Biosecurity New Zealand website and the MAF 0800 number set up to manage didymo calls.

Delimiting surveys and public awareness are identified as immediate priorities. Rivers in Otago and Southland regions are identified for sampling. None test positive.

16 November 2004 MAF Biosecurity New Zealand formally briefs the Minister for Biosecurity on the detection. The Minister is provided with regular updates as the response progresses.

12 November 2004 Discussions with Environment Southland, NIWA, the Ministry of Health and Department of Conservation. Organisations nationwide conducting river surveys or research are instructed what to look for and asked to report suspected didymo.

A factsheet and river signage is developed. Experts, both national and international, are identified to form a technical advisory group.

21 October 2004 –Biosecurity New Zealand is advised of the find. An incorrect record in a 1928 report suggests initially that didymo may have been present in New Zealand for some time. This is later discredited, and the Waiau find is treated as the first credible detection, leading to Biosecurity New Zealand's involvement leading the response.

Despite Didymo behaving as an invasive species overseas, it is clear that there is virtually no scientific information available -on its biology, ecology, impacts or on methods for control.

19 October 2004 – NIWA identifies the sample as Didymosphenia geminata.

15 October 2004 – An unusual algal growth is noted during a routine survey in the lower Waiau river in Southland by NIWA and Southland Fish and Game Staff. A sample is taken for further analysis.