Dive 01: Aunuʻu Unit of National Marine Sanctuary American Samoa
April 27, 2017
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Dive 01: An Octopus for (Almost) Octopus Friday

During the first dive of the expedition, while exploring in the Aunuʻu Unit of National Marine Sanctuary of American Samoa, the team encountered this colorful little octopus. Video courtesy of the NOAA Office of Ocean Exploration and Research, Mountains in the Deep: Exploring the Central Pacific Basin. Download (mp4, 20.7 MB)

After a successful week of outreach activities in Pago Pago, American Samoa, NOAA Ship Okeanos Explorer departed at 08:30 this morning to begin the Mountains of the Deep: Exploring the Central Pacific Basin expedition. Our first dive site was in the Aunuʻu Unit of National Marine Sanctuary of American Samoa, a small volcanic island approximately 10 nautical miles southeast of Pago Pago. The sanctuary area encompasses 15 square kilometers (5.8 square miles) and borders the island on three sides. The goal of this dive was to gather deepwater data about the habitat and biological communities to better understand their diversity and distribution, with a specific interest in bottom fishes, such as snapper and grouper. This dive had been identified as a priority by NOAA's Office of National Marine Sanctuaries. This was the first-ever deepwater exploration of the Aunuʻu Unit and we were not disappointed. The dive began at approximately 14:45 SST at a depth of 360 meters and continued upslope in search of bottomfish habitat. Much of the dive climbed a steep cliff that marked the edge of a coral platform that has grown on top of the volcanic rocks that formed the Samoan Islands. Finer sediments derived from the coral platform were transported down the steep slope within small grooved channels along its face. Though the dive was short, we accomplished our goal of locating bottomfish as well as several different species of corals – including cup corals, black corals, and sea fans. Other biology highlights included zoanthids, sea stars, a small aggregation of shrimp, an unusual crab – potentially an arrow crab, a squat lobster, duckbill fish, and an octopus. Much of the dive was spent climbing the steep wall which did not appear to have many crevices or caves. This lack of hiding areas likely explains the relatively few number of fish we saw. The remotely operated vehicles were secured on deck at 16:45 SST. We then began mapping operations. We will spend the next two days collecting sonar data as we transit to our next operating area, the high seas north of the Manihiki Plateau.