Award: OCE-1028862

Deep-sea hydrothermal vents are hot spring oases that support unique ecosystems, thriving in the otherwise cold, dark, deep ocean. In 2009 the first Marine Protected Areas (MPAs) for deep-sea hydrothermal vents in U.S. waters were established as part of the Marianas Trench Marine National Monument. These vents are located along the Mariana arc and back-arc spreading center. In 2010 we joined Japanese colleagues on the first cruise dedicated to the study of animal biodiversity and population connectivity at southern Mariana back-arc vents. Operations during the cruise included nine dives with the submersible Shinkai 6500, on which samples were collected to catalog the diversity of species at the vents. We visited vents on-axis and off-axis of the spreading center at ~3000-m (~2 miles) depth. You can follow our cruise blog at: http://ventlarvae.blogspot.com. Our NSF-sponsored work included seven deployments of sub-surface moorings, six of which supported a plankton pump to sample larvae from the water column near-bottom. As the early life history stage of many of these species, larvae disperse in the water column, providing the means by which to connect populations at discrete seafloor vent habitats. Although collected at ~3000-m depth, many larvae stayed alive and active on board ship, and we videotaped individuals to observe larval swimming behavior. We preserved and sorted the plankton samples to assess larval abundance and diversity. One of our moorings supported a current meter near-bottom to record flow speed and direction, allowing us to estimate local-scale (on the order of 10 km) larval dispersal by passive transport during the cruise. Results of our local-scale study will be considered in the regional context of ecosystem management and protection for the MPAs in the new Monument and also in the broader context of biogeography of deep-sea vent fauna, through our involvement with InterRidge and the International Network for Scientific Investigations of Deep-Sea Ecosystems (INDEEP). We reported on the research cruise in the OCEANS 2011 MTS/IEEE conference proceedings and in the 2011 InterRidge News. Our method to analyze larval swimming trajectories was submitted to a journal for peer review. Results for larval abundance, diversity, behavior, and local-scale dispersal in the southern Mariana Trough will be submitted soon to journals for peer review. In addition to the scientific results and implications for the Monument, broader impacts of this project included the international cultural exchange between U.S. and Japanese scientists and students and the training of an undergraduate student in interdisciplinary research. Last Modified: 06/07/2012 Submitted by: Stace E Beaulieu