MARINE BIOSECURITY Porthole

Mediterranean fanworm

Sabella spallanzanii

[Image: Geoffrey Read, NIWA]

Mediterranean fanworm (Sabella spallanzanii, (Gmelin, 1791))

Status in New Zealand

Present in some areas of New Zealand

Legal Status in New Zealand

Under management

Description

The Mediterranean fanworm is native to the Mediterranean and Atlantic coast of Europe. It typically occurs in subtidal habitats to a depth of 30 metres that are protected from wave exposure. The fanworm attaches to solid structures such as wharf pilings and shells or small, hard substrata in soft sediments. It has been introduced to Australia and was first detected in New Zealand in 2008. It is now present in a number of New Zealand harbours. The Mediterranean fanworm can persist in a range of water temperatures and salinity. It grows rapidly in summer months and can live for 2-5 years. Larvae may last in the water column for up to 20 days before settling to attach on the seafloor or on port or harbour infrastructure. The Mediterranean fanworm is spread to new locations primarily within vessel biofouling, although the movement of aquaculture equipment or other marine structures may also contribute to its spread.

Why is it a problem?

The Mediterranean fanworm can form dense colonies of up to 1000 individuals per square metre that will exclude the settlement of other organisms. It also has a high filtering ability that may influence the composition of planktonic communities and abundance of some species. The presence of the Mediterranean fanworm in areas where mussels or oysters are located may affect their growth due to competition for food. The tubes of the Mediterranean fanworm may attached themselves to aquaculture equipment or vessels and this may increase harvesting or fuel costs, respectively.

This footage, taken in Waitemata Harbour, Auckland, New Zealand, shows forests of fanworms attached to the underside of floating docks. [Crispin Middleton, NIWA].

What do they look like?

Key features

The Mediterranean fanworm is a sessile organism that has a long leathery, flexible tube that is pale brown in colour and has a muddy appearance. These tubes normally grow to a length of 10-50 centimetres although in New Zealand individuals 80 centimetres in length have been recorded. It is larger than other native fanworms in New Zealand. The Mediterranean fanworm extends a spiral fan of yellow-orange filaments to collect plankton from the water column

 image

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