Dissertation Research: Invasion and Coexistence of the Ascidian Botrylloides Violaceous in Subtidal Fouling Communities Along the Strait of Juan de Fuca, WA

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The composition of marine ecosystems is increasingly affected by non-native species. This project seeks to understand how ecological processes influence broad-scale patterns of invasion of the non-native ascidian, Botrylloides violaceous, into coastal marine communities in the northeast Pacific Ocean. Laboratory and field experiments will be performed to quantify the effects of abiotic variables, such as temperature and productivity, on B. violaceous population growth. This will then be compared to population growth observed in different experimental conditions at four sites along the Strait of Juan de Fuca, WA in order to quantify the effect of biotic factors, such as competition and predation, on B. violaceous success. These observations and experiments will also be used to distinguish between three plausible mechanisms for the observed coexistence of B. violaceous with other species: competitive intransitivity, competition-colonization trade-off and the storage effect. In total, this research will identify the mechanisms that permit an invader to increase from low density and persist. By disentangling abiotic versus biotic variables affecting invasions across scales and exploring co-existence mechanisms, this study will synthesize important issues in theoretical, experimental and applied ecology to provide a framework for future studies of invasions. Although invasive ascidians are a growing global problem, they have received little attention and their abundance in natural habitats throughout the region is virtually unknown. In addition to the proposed work, public education projects will be spearheaded to better understand the geographic extent of invasive ascidians. Efforts will focus on public awareness, including educational workshops and the involvement of local SCUBA divers in invasive ascidian monitoring throughout coastal Washington State.