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UBC Theses and Dissertations

The role of recreational boating in the introduction and spread of marine invasive species Clarke Murray, Cathryn Lynne


Introduction and spread of non-indigenous species is a significant threat to the preservation of global biodiversity. Human-mediated vectors are responsible for transporting potentially invasive species to new habitats throughout the world. This research investigates the role of recreational boating movements as a vector for introduction and spread of invasive species. A baseline survey of subtidal fouling communities was conducted using artificial substrates in marinas of the southern Strait of Georgia, British Columbia. There was both a high presence of non-indigenous species and high non-indigenous species fouling cover in some marinas, indicating a likely negative impact on native communities. A dive survey which examined the species present on the underwater surfaces of recreational boats in marinas throughout British Columbia showed that more than two-thirds of boats examined had macrofouling present and one-quarter had one or more known non-indigenous species. In combination, a boater questionnaire was used to describe the movements and behaviours of the boaters themselves and behaviour patterns indicated a risk of non-indigenous species transport. The results of the dive survey and boater questionnaire were then used to develop a model that predicts the presence of fouling on boats based on three variables (age of antifouling paint, time in water and incidence of long trips). The biomechanical properties of non-indigenous species were compared to native species and non-indigenous species had both stronger attachment and lower drag than similar native species, indicating they have the ability to remain attached to fast-moving marine vessels. Finally, a statistical analysis was conducted comparing environmental, demographic and vector variables in explaining the spatial distribution of non-native species. The results showed that recreational boating played a stronger role in the distribution of subtidal non-native species than the original introduction vectors, aquaculture and shipping. This body of research demonstrates that recreational boating is a significant vector for the introduction and spread of invasive species in this region and around the world. It is the first comprehensive study of the recreational boating vector in Canadian marine waters and the results have important implications for the prevention of new introductions and the preservation of biodiversity.

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