Starting the invasion pathway: the interaction between source populations and human transport vectors

Abstract

Human transport hubs, such as shipping ports, airports and mail centers are important foci for the spread of non-indigenous species. High relative abundance in a transport hub has been proposed as a correlate of invasion success, since abundant species are thought more likely to colonize vectors and to be transported more frequently. We here evaluate the relative importance of vector characteristics and local source assemblages in determining the pool of species that is transported by hull fouling on recreational boats. We compared the resident fouling communities of three recreational boat harbors in Australia with the assemblages on the hulls of boats that travel between them. We used data on the recent travel and maintenance history of the boats to evaluate correlates of transport probability and the potential for intra-coastal spread of fouling organisms. Invertebrate assemblages on heavily fouled vessels reflected the composition of biotic assemblages within the marina in which they were moored, but by itself, relative abundance in the source port was not a reliable predictor of transport probability. More important was the age of the antifouling paint on the vessels' hulls, which acted selectively on some groups of organisms. Movements of vessels were characterized by 'fidelity' (vessels remaining close to homeport) interspersed with 'promiscuity' (vessels traveling to a diverse pool of destinations). In an infested harbor, measures taken to increase the resistance of vectors to colonization by the invader should be effective in slowing the rate of spread to other locations, by decreasing the overall frequency of transport.

Artificial structures in sediment-dominated estuaries and their possible influences on the ecosystem

“…This pattern coincides with many other studies on artificial substrates (e.g. Davis et al, 1982;French and Livesey, 2000;Bustamante et al, 2007). In our study, some species were present on the groynes in high abundances such as B. ligerica which is also found in other Wadden Sea estuaries (cf.…”

“…When nonindigenous species (NIS) occur on artificial structures (Ruiz et al, 2009;Glasby et al, 2007;Tyrrell and Byers, 2007;Wasson et al, 2005) these substrates may serve as stepping stones for invasive alien species (Apte et al, 2000;Wilhelmsson and Malm, 2008). Commercial ports and recreational marinas therefore provide the first habitats in a colonization corridor for introduced species (Floerl and Inglis, 2005;Bulleri and Airoldi, 2005). However, artificial substrates were also found to present refuges for endangered species of crustaceans (Krone and Schröder, 2011) or limpets (García-Gómez et al, 2010).…”

Marine biosecurity: protecting indigenous marine species

“…Studies have shown that paint age can have a significant influence on biofouling communities, with older paint allowing the establishment of greater quantities of fouling. 119 Unpainted surfaces, such as those that evade actual paint coverage, eg, regions covered by support frames whilst the vessel is in dry dock and niche areas such as the propeller shaft, may allow sufficient area to facilitate biofouling. 120 In addition, minor failures (,0.5 cm wide) in the anti-fouling system, as a result of accidental damage during daily operations (eg, anchor damage, vessel groundings or minor collisions) can also lead to the rapid establishment of fouling species, including NIS on the unprotected areas.…”

Human-mediated transport determines the non-native distribution of the anemone Nematostella vectensis, a dispersal-limited estuarine invertebrate

“…A recent study of Elkhorn Slough, California, revealed the presence of numerous invasive taxa present elsewhere along the west coast, despite the absence of any commercial ports (Wasson et al 2001), and fouling of recreational boats is probably a major vector for the movement of species between such habitats (Floerl & Inglis 2005). Fouling has been implicated in the global expansion of numerous invasive taxa, including crustaceans (Zardus & Hadfield 2005, Otani et al 2007), bryozoans (Marchini et al 2007), mollusks (Ricciardi 1998) and tunicates (Bullard et al 2007).…”

“…A substantial proportion of these invasions have occurred in estuarine ecosystems, largely due to their association with common vectors of introduction such as commercial shipping and recreational boating , Carlton 2001, Floerl & Inglis 2005. The ecological consequences of estuarine invasions can be substantial (Grosholz 2002), and the associated costs in terms of lost ecosystem services may require significant investment in the management of threats posed by introduced populations (Williams & Grosholz 2008).…”