EK80 Water Column Sonar Data Collected During PC2404_Leg1

This project will provide critical data to NOAA and to the Mesophotic and Deep Benthic Communities (MDBC) projects. These data will be used for restoration and to guide future science-based management decisions. Without this project, NOAA and partners will not be able to use the best available science to guide their actions, including protection and restoration actions for sensitive communities. This expedition is part of the DWH Open Ocean TIG Final Restoration Plan 2 for MDBC. This plan will have direct consequences for defining the distribution, connectivity, and ecology of vulnerable ecological communities and guiding wise use of the living marine and energy resources. Operations To Be Conducted (A) 12 hr ROV operations (0700 – 1900). Mohawk ROV will be used to conduct transect surveys, video, and still image documentation of coral and reef fish communities. Collections of corals and other invertebrates will also be taken throughout the dives for genetic and isotope analysis. Details on deployment and recovery are provided below in section 2.7 (A). (B) CTD casts with water samples at each ROV dive site to be conducted at night (probably between 1900 - 0000). (C) Four landers to be deployed overnight (between 1900 - 0700) unless the ship prefers to deploy them during the daytime. Two will be in depths < 300 m and two will be in depths < 1000 m. Lander specifications have been sent to the ship. They will be deployed from the side sampling station winch, lowered to ~ 20 m above the seafloor and then acoustically released by the science party. (D) Up to four sets of 3 ARMS (Autonomous Reef Monitoring Structures) will be deployed during the day (between 0700 - 1900). An elevator will be used to deploy all 3 ARMS in a single ROV dive. Specifications on the elevator have been provided to the ship. The elevator will be deployed from the side sampling station winch and lowered to the seafloor during the dives ARMS are to be deployed. The ROV will navigate to the elevator and retrieve the ARMS for placement on the seafloor. The elevator will be recovered once all ARMS have been retrieved by the ROV. (E) Opportunistic MBES to be conducted at night (between 1900 - 0700) when it fits into the schedule.