Summary

Hull fouling has been identified as a primary vector for marine invaders, however few studies have examined the different opportunities for invasion presented by commercial ships versus recreational yachts. One important difference between commercial and recreational vessels relates to the fact that for the past two decades the active biocidal agent in antifouling paints used by most commercial vessels has been tributyltin (TBT), whereas recreational boats have been restricted to copper-based paints. We investigated the development of sessile assemblages on settlement plates deployed in two recreational and two commercial estuaries in NSW, Australia. The plates were painted with copper diuron, copper zinc or TBT antifouling paint around their edges and deployed at multiple sites within each estuary. Preliminary sampling after three months suggests that abundances of non-indigenous or native biota differ between commercial and recreational estuaries and between antifouling treatments. Specifically, non-indigenous species are more abundant in recreational estuaries, while native species are more abundant in commercial estuaries and NIS are least abundant on TBT-treated plates. The outcomes of this study will have implications for the monitoring and management of recreational vessels as a major source of marine invaders.