Abstract: Elevated temperatures and ocean acidification are both threatening the Southern Ocean. The effects of these environmental changes are poorly understood, but preliminary data suggest that they are driving a biological invasion. Specifically, large populations of skeleton-crushing king crabs, Paralomis birsteini, have been detected off Marguerite Bay on the West Antarctic Peninsula. These crabs appear to be invading the continental shelf region where benthic communities have evolved in the absence of such top-predators. Thus, this invasion could result in a wholesale restructuring of the Antarctic benthic ecosystem. The proposed work seeks to document this invasion and better understand the effects of the introduction of P. birsteini on the ecology of this region. A towed underwater vehicle will be used to photographically image communities, and communities with and without P. birsteini will be compared quantitatively. Additionally, crabs will trapped and various aspects of their morphology and physiology will be assessed. This research is unique in that it will document a biological invasion in real-time and it will therefore enhance our general understandings of the drivers of invasion and resilience in biological communities. Results will be widely disseminated through publications as well as through presentations at national and international meetings. In addition, raw data will be made available through open-access databases. This project will support the research and training of undergraduate and graduate students and will foster an international collaboration with British scientists. Researchers on this project will participate in outreach thorough the development of K-12 curricular materials.