Progress on Mediterranean fanworm removal
Science Centres: Aquatic Biodiversity and Biosecurity
NIWA is providing scientific and technical support to MAF Biosecurity New Zealand’s programme to rid Lyttelton Port of the invasive Mediterranean fanworm.
The Mediterranean fanworm, Sabella spallanzanii, is one of eight unwanted marine species targeted in MAF Biosecurity New Zealand’s (MAFBNZ) port surveillance programme. It is highly invasive with no known predators and can thrive in a wide range of habitats. It could displace existing species and foul port structures, vessels, and aquaculture farms.
Early measures show promise
The fanworm was first found in Lyttelton Port in March 2008 and later identified by NIWA taxonomist Geoff Read (see story in ABBU28). MAFBNZ contracted divers from NIWA and Diving Services New Zealand (DSNZ) to systematically search for and remove fanworms from the port. Repeat searches in August and November 2008 suggested that the fanworm population could be reduced and eventually eliminated through this technique.
Local elimination programme begins
In April this year, MAFBNZ instigated a 5-year $3.6 million programme to
eliminate Sabella from Lyttelton Port. The aim is to reduce the numbers to such a low level that the population can no longer successfully reproduce.
DSNZ divers were again contracted to search the port and manually remove all suspected Sabella specimens. This treatment will take place every three months for up to two years, the first two rounds being completed in April and and June/July. NIWA is evaluating the success of treatment and continues to identify all fanworms collected through the Marine Invasives Taxonomic Service.
Evaluating the success of the programme
NIWA scientists are using statistical analysis and GIS mapping techniques to identify sites or situations in which Sabella is most likely to be found. NIWA divers are carrying out surveillance surveys to identify Sabella “hotspots” that will require removal during the next treatment round, monitor the effectiveness of previous Sabella removal, and provide an early indication of spread (if any) to areas outside the inner Lyttelton Port. Surveillance surveys are carried out in autumn and spring to alternate with the existing MAFBNZ targeted marine surveillance surveys in summer and winter.
As an additional measure of the success of the elimination programme, NIWA is also conducting ‘sentinel monitoring’ to determine whether Sabella is reproducing and recruiting within the port. This involves submerging settlement plates to monitor recruitment of small Sabella that may not be obvious to divers.
Early results suggest effective treatment
Results of the surveillance surveys suggest that the worms were at low densities (less than 0.15 worms per pile) throughout most of the port prior to the April 2009 treatment and that the treatment programme is effective at reducing them below this level.
“The Lyttelton fanworm population was detected while it was still very small and localised”, says NIWA Principal Scientist Graeme Inglis, who is leading the NIWA operations. “This gives us a good shot at removing it before it can become firmly established in New Zealand.”
Divers have now removed more than 200 Sabella specimens from the harbour. The programme will be reviewed in October this year to ensure that the treatment remains effective.
Contact: Dr Graeme Inglis, NIWA Christchurch or Dr Peter Stratford, MAFBNZ
To report a suspicious organism, phone MAF Biosecurity New Zealand's hotline: 0800 80 99 66.
