The relative contribution of vectors to the introduction and translocation of invasive marine species

Whether intentional or not, humans have been responsible for the translocation of invasive marine species. The indicative representations of association suggest that biofouling has been the most prevalent mechanism contributing to such invasions across the globe. Biofouling is one of the oldest mechanisms of human-mediated transport of marine species, beginning with early human movements on small scales and eventually leading to world explorations with the European Expansion from 1500 AD onwards.The most common means of biofouling is marine species attaching themselves to any part of a vessel, or any equipment attached to or onboard the vessel, aquaculture equipment and mooring devices. In contrast, ballast water is a relatively new vector of transport, with the earliest ballast water use recorded in the late 19th century. Ballast water – water (including sediment that has been contained in water) held in tanks and cargo holds of ships to increase stability and manoeuvrability during transit – represents an expansion of transport opportunity to the vast majority of the benthic species associated with biofouling.This project assessed the relative contributions of known marine pest vectors in terms of the introduction and translocation of marine invasive species on a national basis (in Australia) through a review of the National Port Survey Database (NPSD) and on a worldwide basis through a literature review.The information represented by the global dataset and the NPSD provide a useful tool for identification of species associations with modern vectors of transport, and the opportunity to identify likely relationships for future entry. Analysis of the global dataset indicated that more species have life history characteristics associated with biofouling (55 per cent) than any other vector. The second highest association was with ballast water (31 per cent). A similar relative contribution was found in the Australian context through analysis of the NPSD, with biofouling contributing 60 per cent of species association and ballast water 24 per cent.