Overland transport of recreational boats as a spreading vector of zebra mussel Dreissena polymorpha

Abstract

In aquatic ecosystems invasive species are among the most important threats to biodiversity worldwide. Understanding the dispersal mechanisms of aquatic invaders is very important for protection and management of vulnerable water bodies. Here we ask how recreational boats that are transported overland could contribute to the dispersal of invasive zebra mussels among lakes in Switzerland. Using a questionnaire sent to registered boat owners, we surveyed properties of transported boats and collected information on self-reported mussel fouling and transport activities of boat owners. We also sampled boat hulls at launching ramps and harbors for biofouling invertebrates. Boats that were kept seasonally or yearround in water were found to have high vector potential with mussel fouling rates of more than 40 %. However, only about 6 % of boats belonging to these groups were transported overland to other water bodies. Considering that approximately 100,000 recreational boats are registered in Switzerland, we estimated that every year around 1400 boats fouled with mussels are transported overland. Such boats pose a high risk of distributing zebra mussels between water bodies. Our results suggest that there is a considerable risk that recreational boats may spread new fouling species to all navigable water bodies within the study area. We speculate that one such species could be the quagga mussel, which has not yet invaded lakes in Switzerland. On a more positive note, our study has identified the group of high-risk boats so that possible control measures would only affect a relatively small number of boat owners.

Detachment rates of dreissenid mussels after boat hull-mediated overland dispersal

“…The results support that dreissenids can disperse long distances into isolated lakes via the boat hullmediated introduction pathway. This is in accordance with the recorded dispersal of zebra mussels via several long-distance jumps (Wilson et al, 1999) and the reported dispersal via recreational boats in Ireland and Switzerland (De Ventura et al, 2016). The possibility to disperse implies that legislative regulation to clean, drain and dry boats (e.g., Clean Boating Act, 2008) and educational campaigns to stop the spread of dreissenids via boats hulls are important management tools to decrease the release of dreissenids into uninfested lakes.…”

“…These vectors enable continued spread in an already colonized river basin as well as long-distance dispersal, including overland transport to isolated water bodies by water craft. In the case of the latter, recreational boats are among the main vectors (Buchan & Padilla, 1999;De Ventura et al, 2016). Several authors report introductions due to ballast water exchange (Johnson & Carlton 1996) and secondary spread due to discharge of water contained in boats (Johnson & Carlton, 1996), macrophytes attached to anchors, propellers or boat trailers (Johnson & Carlton, 1996;Johnson et al, 2001) or boat hulls Pollux et al, 2003).…”

“…Mussels must be able (1) to attach to the boat hull (or other submerged parts such as an anchor, outboard motor or trailer), (2) to survive air exposure and prevent desiccation during overland transport and (3) establish a viable population either after detachment or release of spat during launching or sailing. The zebra and quagga mussel attach to a wide variety of materials (Ackerman et al, 1992(Ackerman et al, , 1995Marsden & Lansky, 2000;Kobak, 2004;Mueting et al, 2010), including commonly used materials for the construction of boat hulls such as aluminium and fibreglass (Marsden & Lansky, 2000;Mueting et al, 2010;De Ventura et al, 2016).…”

Eradication of Gyrodactylus salaris infested Atlantic salmon (Salmo salar) in the Rauma River, Norway, using rotenone

“…The vector of within-watershed dispersal into area 3 remains unclear. Our findings suggest that international shipping is the main vector, but secondary vectors, such as recreational boating within and between waters (Johnson et al 2001;De Ventura et al 2016) or alternatively passive transport by water birds (e.g. Wood 2002;Figuerola and Green 2002;Charalambidou et al 2003;Reynolds et al 2015) or fish (Markovic et al 2009) may be potential vectors of dispersal of the species into new areas within the watercourse.…”

Physiology in ecological niche modeling: using zebra mussel's upper thermal tolerance to refine model predictions through Bayesian analysis

“…The limitation of native data could be attributed to dispersal or biotic interactions (Soberón and Peterson 2005); the difference in environments between native and global distributions is also termed niche unfilling (Guisan et al 2014). In our zebra mussel study, the major reason could be that the human mediated dispersal has greatly expanded the accessible area to zebra mussel (Griffiths et al 1991, Gallardo et al 2015, De Ventura et al 2016. Another reason for the relative narrowness of native occurrence data is adaptation of introduced populations to previously limiting conditions in the invaded range (Prentis et al 2008, Moran andAlexander 2014).…”