Biosecurity news

Cawthron Institute: The Mediterranean fanworm Sabella spallanzanii in a soft sediment habitat at Waitemata Harbour.
21 October 2020

Cawthron Institute study finds invasion of Mediterranean fanworm impacts marine animal and bacteria communities

A recently published study by Cawthron Institute has found that the presence of Mediterranean fanworm (Sabella spallanzanii), a high-profile marine pest first detected in New Zealand in 2008, has a significant, but subtle impact on soft-sediment coastal environments.
The study involved a 6-month field experiment between September 2017 and March 2018 in subtidal habitats along the Rangitoto Channel in Auckland’s Waitemata Harbor. It found that the fanworm did not necessarily have an impact on the abundance of life in benthic environments, but it did show that the fanworm’s presence changed the composition of that life.

The fanworm is considered by scientists to be an ‘ecosystem engineer’ because its feeding fans and leathery protective tubes create a dense, canopy-like structure extending up to 50 cm from its base. These structures can change several key features of the nearby environment – they block light, they provide a habitat for other species to live in, and they change the way water moves through the seabed environment. All research conducted to date suggests that the effects of fanworm incursions in New Zealand are likely to be negative and may have both environmental and economic impacts.

Evidence from Australian studies suggest it is conceivable that S. spallanzanii could become a nuisance fouler on subtidal aquaculture systems in New Zealand. The fanworm’s high-filtering capacity could make it a competitor to cultured filter-feeding species such as oysters and mussels.

Although this study has found evidence of subtle negative impacts, further studies over a longer period are required to observe the long-term impacts of fanworm incursion. This knowledge would enable an assessment of the threat widespread incursions might represent for New Zealand’s ocean economy and environment.

Download a full copy of the study here: