Abstract
Ships and boats may transport whole communities of non-indigenous species (NIS) through hull biofouling, some members of which may become invasive. Several studies have evaluated the diversity of these communities, but very few have analyzed the survival of organisms after their voyages into different and potentially inhospitable conditions. This factor is important to consider because the last port of call approach for risk assessments assumes that if the conditions observed in the last port of call are different from those observed in a receiving port, risks are diminished or null. Using an innovative experimental system, we tested the survival and recovery of the marine blue mussel (Mytilus edulis) and the freshwater zebra mussel (Dreissena polymorpha) by exposing them to adverse salinity conditions at varying temperatures to simulate ships and boats transiting to ports or marinas with contrasting environmental conditions. Both mussel species, which are well-known for their adaptability to new environments as aquatic NIS, survived better at colder temperatures, with blue mussels surviving up to 14 days in freshwater, and zebra mussels up to 8 days in marine water. This highlights the importance of considering the resistance of fouling organisms to adverse conditions in vector and species risk assessments.
Highlights
Aquatic invasive species are non-indigenous species (NIS) that have considerable impacts on ecosystem function, biological community composition, and global economies in marine coastal and freshwater environments (Bax et al, 2003; Molnar et al, 2008; Havel et al, 2015; Gallardo et al, 2016)
Mytilus species are known for their plasticity which allows them to adapt to new environments and M. galloprovincialis and M. edulis have been introduced by aquaculture operations on the Pacific coast of North America and many other areas worldwide (Moreau et al, 2005; Gaitán-Espitia et al, 2016; Mathiesen et al, 2017)
Higher mortality was observed in zebra mussels control tanks with up to 55% dying in the warmer conditions (Figure 5)
Summary
Aquatic invasive species are non-indigenous species (NIS) that have considerable impacts on ecosystem function, biological community composition, and global economies in marine coastal and freshwater environments (Bax et al, 2003; Molnar et al, 2008; Havel et al, 2015; Gallardo et al, 2016). Important introduction vectors include vessels (e.g., commercial ships and recreational boats) that may transport organisms into novel environments where they can become invasive (Molnar et al, 2008; Seebens et al, 2013). Most work on shipping-related introductions of NIS has focused on ballast water (Bailey, 2015), biofouling by a diverse assemblage of fouling organisms (Bailey et al, 2012; Chan et al, 2012; Adams et al, 2014; Linley et al, 2014) on submerged ship surfaces, including hulls, sea chests, etc., may be an important vector (Coutts et al, 2010a,b; Sylvester et al, 2011; Chan et al, 2016, 2019). Likewise, biofouling of smaller boats (recreational, fishing, etc.) may be an important source of NIS introductions in many areas (e.g., Davidson et al, 2010; Ashton et al, 2014; Zabin et al, 2014; Pelletier-Rousseau et al, 2019)
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