Hull fouling as an invasion vector: can simple models explain a complex problem?

Abstract

Summary 1. The most effective way to manage nonindigenous species and their impacts is to prevent their introduction via vector regulation. While ships’ ballast water is very well studied and this vector is actively managed, hull fouling has received far less attention and regulations are only now being considered despite its importance for introductions to coastal, marine systems. 2. We conducted comprehensive in situ sampling and video recording of hulls of 40 transoceanic vessels to assess propagule and colonization pressure in Vancouver and Halifax, dominant coastal ports in Canada. Concomitant sampling was conducted of harbour fouling communities to compare hull and port communities as part of a vector risk assessment. 3. Although this vector has been operational for a long time, hull and harbour communities were highly divergent, with mean Sørensen’s similarity values of 0·03 in Halifax and 0·01 in Vancouver, suggesting invasion risk is high. Propagule pressure (up to 600 000 ind. ship−1) and colonization pressure (up to 156 species ship−1) were high and varied significantly between ports, with Vancouver receiving much higher abundances and diversity of potential invaders. The higher risk of fouling introductions in Vancouver is consistent with historical patterns of successful hull fouling invasions. 4. The extent of hull fouling was modelled using ship history predictors. Propagule pressure increased with time spent in previous ports‐of‐call and time since last application of antifouling paint, whereas colonization pressure increased with time since last painting and with the number of regions visited by the ship. Both propagule and colonization pressure were negatively related to the time spent at sea and the latitude of ports visited. 5. Synthesis and applications. A major challenge for applied invasion ecology is the effective management of introduction vectors. We found that hull fouling has a strong potential for introduction of many species to coastal marine habitats and that management should be considered. Simple variables related to the vessels’ hull husbandry, voyage, and sailing patterns may be used to predict and manage hull fouling intensity. The results presented here should interest policy makers and environmental managers who seek to reduce invasion risk, and ship owners seeking to optimize fuel efficiency.

Costs and benefits to European shipping of ballast-water and hull-fouling treatment: Impacts of native and non-indigenous species

“…In this work, this hypothesis was formulated on the basis that biofouling is recognized to be among the most important vectors of species introduction (Reise et al, 1999;Minchin et al, 2003;Olenin et al, 2010;Sylvester et al, 2011). NIS arriving through this vector have thus been able to survive the antifouling measures used by ships as well as natural ecological barriers to their movement such as temperature, salinity and hydrodynamic factors; as a result, they differ from species resident in their native range.…”

Assessing introduction risk using species’ rank-abundance distributions

“…Characterization of assemblages in invasion vectors has typically relied on CP and total PP [6,7]. Here, we extended this approach to examine rank-abundance distributions and CP : total PP relationships for a variety of common taxa found in ships' ballast water and to explore the importance of voyage route and BWE.…”

Survival of ship biofouling assemblages during and after voyages to the Canadian Arctic

“…Many marine vectors, such as ships’ ballast water and fouled hulls, marine debris, and bait worm packaging, often inadvertently translocate large, mixed-species assemblages during a single introduction event (e.g. Gregory 2009; Sylvester et al 2011; Briski et al 2013; Fowler et al 2016). In general, only a fraction of individuals and species survive transport and are introduced to a new location (Lockwood et al 2009; Briski et al 2014; Chan et al 2015a).…”