Heidi N. Gartner, Cathryn Clarke Murray, Melissa A. Frey, Jocelyn C. Nelson, Kristen J. Larson, Gregory M. Ruiz and Thomas W. Therriault
Abstract
Marine fouling communities on artificial structures are invasion hotspots for non-indigenous species (NIS). Yet, little is known about NIS infouling communities of British Columbia (BC), Canada. To determine NIS identity and richness in BC fouling communities, we deployed settlement plates at 108 sites along the coast of BC between 2006 and 2012. Of the 295 invertebrate taxa identified to species, 20 were NIS while an additional 14 were cryptogenic, including several global invaders. This study documents the range expansion of tunicates Botrylloides violaceus Oka, 1927 and Botryllus schlosseri (Pallas, 1766), including the first known records on Haida Gwaii. NIS were detected within each of the six distinct geographic regions with the southern, more populated regions of BC (Straits of Georgia and Juan De Fuca) having the highest NIS richness and frequency of occurrence compared to the less populated northern regions. This study provides a contemporary baseline of invertebrate NIS identity and richness in fouling communities that will allow comparisons through time and a means to focus research and prioritize management efforts.
Key words: non-native species, introduced species, invasion, Northeast Pacific, West Coast, North America, biofouling
The introduction of potentially invasive species remains a global threat to biodiversity and ecosystem services. The spatial distribution of introduced species can provide insight into present and historical vectors of invasion. Here, we aim to investigate the influence of environmental, demographic and vector variables on the spatial distribution of non-indigenous species (NIS) in coastal marine ecosystems.
Coastal British Columbia, Canada.
We used subtidal settlement plates to sample NIS richness at 81 sites. Spatial patterns for seventeen environmental, population, and vector variables were created using a Geographic Information System (GIS). We used multiple regression with model selection and spatial autocorrelation to define a statistical model that best explained the spatial distribution of NIS.
Four variables, salinity, human population density, port arrivals and marina propulsiveness (probability of boater travel from home marina), best explained the observed spatial distribution of subtidal NIS. Aquaculture, an original global introduction pathway, did not significantly explain the contemporary distribution of NIS. Results suggest that recreational boating is the most probable pathway of fouling NIS spread in this region, driving their current distribution. Spatial autocorrelation was significant for environmental, demographic, and aquaculture variables. However, marina propulsiveness and attractiveness were not autocorrelated, suggesting that boater behaviour varies on a finer scale.
A simple model using a combination of vector, demographic, and environmental characteristics can explain 43.6% of the variation in the spatial distribution of NIS. Our study provides further evidence that recreational boating is a significant pathway for the contemporary spread of NIS in marine environments. With projected increases in human population, we expect a continued rise in introduction rates and spread in this region and elsewhere in the world.
Here, we report the first records of the non-native amphipod Caprella mutica along the coast of British Columbia, Canada. Between 2006 and 2009, we surveyed marine fouling communities across 81 subtidal sites, and sampled hulls and sea-chests from 18 domestically operated commercial vessels. Caprella mutica was present at 33% of the sites and on 22% of the vessels, sometimes at remarkably high densities (>10,000 individuals m-2). Our findings confirm an extensive distribution of C. mutica along the coast of the northeast Pacific, and offer additional evidence in support of hull fouling as an important vector for secondary spread. Key words: caprellid, introduced, northeast Pacific, biofouling, sea-chest, vector, museum records
Marine fouling communities on artificial structures are invasion hotspots for non-indigenous species (NIS). Yet, little is known about NIS in fouling communities of British Columbia (BC), Canada. To determine NIS identity and richness in BC fouling communities, we deployed settlement plates at 108 sites along the coast of BC between 2006 and 2012. Of the 295 invertebrate taxa identified to species, 20 were NIS while an additional 14 were cryptogenic, including several global invaders. This study documents the range expansion of tunicates Botrylloides violaceus Oka, 1927 and Botryllus schlosseri (Pallas, 1766), including the first known records on Haida Gwaii. NIS were detected within each of the six distinct geographic regions with the southern, more populated regions of BC (Straits of Georgia and Juan De Fuca) having the highest NIS richness and frequency of occurrence compared to the less populated northern regions. This study provides a contemporary baseline of invertebrate NIS identity and richness in fouling communities that will allow comparisons through time and a means to focus research and prioritize management efforts. Key words: non-native species, introduced species, invasion, Northeast Pacific, West Coast, North America, biofouling