The role of disturbance, larval supply, and native community on the establishment of a non-native species on oil platforms in the Santa Barbara Channel

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The invasion and spread of non-native plant and animal species is considered one of the greatest threats to global biodiversity and ecosystem function. In marine ecosystems, offshore structures, such as oil and gas platforms, could facilitate the spread of non-native epibenthic species by acting as “stepping stones” that provide hard substrate habitat that allows dispersal across otherwise unsuitable soft-bottom habitat. Disturbance in the form of periodic maintenance (cleaning) and storm events, which remove the attached epibenthic community, may promote the establishment of non-native species on platforms by opening space and reducing biotic interactions. The non-native crustose bryozoan, Watersipora sp., has colonized a number of oil platforms in the Santa Barbara Channel. Our observations suggest that disturbance is an important mechanism contributing to the successful establishment of this bryozoan. In this ongoing study, we are experimentally 1) testing the role of disturbance and water depth on the establishment of Watersipora on an offshore platform, 2) exploring how larval supply might influence observed patterns, and 3) evaluating the importance of biotic interactions, specifically predation on larvae, in Watersipora recruitment. Results to date suggest that disturbance greatly enhances the establishment of Watersipora, but that this effect varies with depth and the associated availability of larvae. Our study will provide information on factors influencing the establishment of Watersipora, and thus inform decisions developed to manage the spread of non-native species to artificial and natural marine habitats.