By Vihan Dalal, Local Democracy reporter
A mystery aquatic plant found in Jackson Bay has been tentatively identified as Potamilla alba, a species of marine worm.
A biosecurity report tabled at the West Coast Regional Council's Environmental Management Committee says divers conducting surveillance on behalf of the council found the "unidentified species" in February this year.
Biosecurity NZ aquatic team manager Mike Taylor told Local Democracy Reporting the same species was first found at Banks Peninsula in 1951.
According to the World Register of Marine Species, Potamilla alba is typically found in New Zealand waters, although this is the first time it has been identified on the West Coast.
West Coast Regional Council environmental science group manager Shanti Morgan said the worms were "dead white" in colour and 75mm long, with gills up to 10mm long. They were "unlikely" to be harmful.
Mr Taylor concurred, saying the species "does not represent a biosecurity concern".
The worm was found in high concentrations around the Jackson Bay wharf with up to 38 per 10 square millimetres.
The species is yet to be confirmed and is "the best estimate based on one taxonomist's opinion" according to the council's biosecurity manager Emily Rutherford-Jones.
A marine surveillance report from the council says Potamilla alba are known to form "dense clusters that can be dredged in quantity by fishing boats, which may explain the locality of the species underneath the mooring (at Jackson Bay wharf)."
Although Ms Jones could not say if the species is native to New Zealand, she believed it must have been brought to Jackson Bay on ship anchors.
Boats were a "key risk pathway" for the arrival of the species at the wharf.
• LDR is local body journalism co-funded by RNZ and NZ on Air
