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