Water Column Characterization and Deep-sea Coral Trophodynamics on the U.S. West Coast Region

With the expansion of offshore energy as well as changes to Essential Fish Habitat Conservation Areas, there are potential disturbances that may shift trophic interactions by changing the amount, the quality, composition, and source of food supply to deep-sea corals and sponges. While critical in understanding food web dynamics, deep-sea coral and sponge trophodynamics (and its linkages to seeps) is less understood along the U.S. West Coast Region. In collaboration with the Expanding Pacific Research and Exploration of Submerged Systems (EXPRESS) campaign to provide scientific information needed to manage, conserve, and protect deep-sea coral and sponge ecosystems along the U.S. West Coast Region, coral and sponge samples from Oregon to the Channel Islands in Southern California were collected in the fall of 2018 on the R/V Shimada using the ROV Beagle. Tissue samples from deep-sea corals and sponges, in addition to particulate organic matter (POM), were analyzed for stable carbon (d¹³C) and nitrogen (d¹⁵N) isotope variability to understand trophic interactions of deep-sea coral communities. Based on these results and comparison with water column nutrient composition, regional scale characterization of particle flux and trophic linkages were evaluated in order to better understand the distribution of deep-sea coral habitats from 15 sites along the West Coast Region at a depth range of 80 to 600 m. These results therefore essential baseline data to evaluate future impacts as well enhance our understanding of the range and distribution of deep-sea corals along the West Coast Region.