Naval Information Warfare Center (NIWC) Pacific 1 article published in JoVE Environment Coral Reef Arks: An In Situ Mesocosm and Toolkit for Assembling Reef Communities Jason L. Baer1, Jessica Carilli2, Bart Chadwick3, Mark Hatay1, Anneke van der Geer1, Yun Scholten4, William Barnes4, Jenna Aquino1, Ashton Ballard1, Mark Little1, Jared Brzenski5, Xiaofeng Liu6, Gunther Rosen2, Pei-Fang Wang2, Jose Castillo5, Andreas F. Haas4, Aaron C. Hartmann7, Forest Rohwer1 1Department of Biology, San Diego State University, 2Energy and Environmental Sciences Branch, Naval Information Warfare Center (NIWC) Pacific, 3Coastal Monitoring Associates, 4Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, 5Computational Science Research Center, San Diego State University, 6Department of Aerospace Engineering, San Diego State University, 7Department of Organismic and Evolutionary Biology, Harvard University Moored midwater geodesic structures called Coral Arks provide a modular, scalable, and vertically adjustable research platform that can be used to build, monitor, and perturb coral reef communities in previously inoperative areas, including offshore.