PROSPECTIVE DEEP SEA CORAL HABITATS ON MUSICIANS SEAMOUNTS, PACIFIC OCEAN

Musicians Seamounts are located northwest of the Hawaiian Islands and lie just outside the borders of Papahānaumokuākea Marine National Monument. The seamounts are known to have an abundance of deep sea corals, which are found at depths exceeding 2100 m. Deep-sea corals often thrive in high-slope areas where the substrate is hard. In August 2017, the NOAA Office of Ocean Exploration and Research’s Deep-Sea Symphony Expedition (EX1707) mapped Musicians Seamounts aboard NOAA Ship Okeanos Explorer and collected video of the corals using the ROV Deep Discoverer. Multibeam sonar and backscatter intensity data were collected using a Kongsberg EM302 echosounder. Data were then post-processed in CARIS HIPS & SIPS 10.4 to generate bathymetric and backscatter intensity surfaces. Profiles of depth and backscatter intensity were created along the elongate axis of each seamount. Areas along each profile that exhibited both high intensity backscatter return and slope greater than 15 degrees were identified as potential coral habitat. A total of 40 potential habitat sites were identified along the 10 seamounts and the sites are comparable to visual observations made during the NOAA expedition. Further work and ground-truthing by an ROV would need to be conducted to test the reliability of this study’s methods in locating deep sea coral habitat. This study is significant because locating coral habitat is critical, in order to protect these slow-growing deep sea organisms from threats, such as trawling or coral mining. Until recently, scientists did not have extensive knowledge of deep sea corals’ diversity and distribution. However, with advancements in multibeam sonar and backscatter analyses, hydrographers have been able to identify ocean floor areas that are potentially ideal habitat for deep sea corals.