A preliminary assessment of biofouling and non-indigenous marine species associated with commercial slow-moving vessels arriving in New Zealand

Abstract

Vessel traffic is the primary pathway for non-indigenous marine species introductions to New Zealand, with hull fouling recognised as being an important mechanism. This article describes hull fouling on seven slow-moving commercial vessels sampled over a 1 year period. Sampling involved the collection of images and fouling specimens from different hull locations using a standardised protocol developed to assess vessel biofouling in New Zealand. A total of 29 taxa was identified by expert taxonomists, of which 24% were indigenous to New Zealand and 17% non-indigenous. No first records to New Zealand were reported, however 59% of species were classified as ‘unknown’ due to insufficient taxonomic resolution. The extent of fouling was low compared to that described for other slow-movers. Fouling cover, biomass and richness were on average 17.1% (SE = 1.8%), 5.2 g (SE = 1.1 g) and 0.8 (SE = 0.07) per photoquadrat (200 × 200 mm), respectively. The fouling extent was lowest on the main hull areas where the antifouling paint was in good condition. In contrast, highest levels of fouling were associated with dry-docking support strips and other niche areas of the hull where the paint condition was poor. Future studies should target vessels from a broader range of bioregions, including vessels that remain idle for extended periods (ie months) between voyages, to increase understanding of the biosecurity risks posed by international commercial slow-movers.

Keywords:

• barge
• biological invasion
• hull fouling
• shipping
• tug

Acknowledgements

The authors thank Dick Mogridge (Sea-Tow Ltd) and Bruce Lines (Diving Services New Zealand Ltd) for logistical support and field assistance. Thanks are also due to Andrew Bell and Liz Jones (MAF Biosecurity New Zealand) for their input throughout the project, and to anonymous reviewers who provided helpful comments on a draft manuscript. This research was funded by MAF Biosecurity New Zealand (Project ZBS2005-02) and the New Zealand Foundation for Research Science and Technology (OBI contract C01X0502; Effective Management of Marine Biodiversity and Biosecurity).