Okeanos Explorer (EX1702): CAPSTONE American Samoa Expedition: Suesuega o le Moana o Amerika Samoa (ROV/Mapping)

Vessel: NOAA Ship Okeanos Explorer; Expedition Dates: February 16 - March 1, 2017

Project Principals: Kelley Elliott, NOAA/OAR/OER (Expedition Coordinator); Elizabeth Lobecker, NOAA/OAR/OER (Mapping Lead)

Operations for this cruise will be conducted 24 hours/day and consist of daily remotely operated vehicle (ROV), overnight mapping, CTD casts and full shore-based participation via telepresence. Operations will be conducted within several marine protected areas. Operations are planned in the Rose Atoll Marine National Monument, National Marine Sanctuary of American Samoa, offshore (not within) of the National Park of American Samoa, and the waters of both American Samoa and Samoa.

South coast of Tutuila Island, Nautilus exploration (250 - 500 m water depth)

Area

South coast of Tutuila Island, Nautilus exploration (250 - 500 m water depth); North Pacific Ocean; Samoan region, South coast of Tutuila Island

Overview

Date:	February 16, 2017
Max Depth:	526 Meters
Bottom Time:	n/a

Purpose

The dive was cancelled owing to equipment malfunction. The dive never reached bottom.

South coast of Ta'u Island, Marine Sanctuary (500 - 350 m water depth)

Area

South coast of Ta'u Island, Marine Sanctuary (500 - 350 m water depth); Samoan region, South coast of Ta'u (Ta'u Unit)

Overview

Date:	February 17, 2017
Max Depth:	504.9 Meters
Bottom Time:	7 Hours 29 Minutes 38 Seconds

Purpose

The goal of this dive is to generate baseline information on deep sea habitats and biological communities to better understand their diversity and distribution and support management needs of the National Marine Sanctuary of American Samoa, and scientific interests. The dive will begin around 500 m on the southern face of the ridge shown in the bathymetry map. We will climb on the ridge and then continue moving upslope along the crest of the ridge reaching the end of the dive. The dive will begin in precious coral depths and at the lower limit of the bottomfish fishery, then move up into more of the prime depths for bottomfish. A submersible dive was made on the north side of the island in 2005. New species/records of organisms and basalt rock samples from a new dive on the south side of the island may be useful to trace the history of the island.

Rose Atoll Marine Sanctuary Deep (ROV on bottom at 2528 m water depth)

Area

Rose Atoll Marine Sanctuary Deep (ROV on bottom at 2528 m water depth); Samoan region, Rose Atoll (East-flanking ridge extending to east of Rose Atoll)

Overview

Date:	February 18, 2017
Max Depth:	2528 Meters
Bottom Time:	5 Hours 13 Minutes 7 Seconds

Purpose

The goal of this dive was to generate baseline information on deep sea habitats and biological communities, particularly deep-sea coral communities, to better understand their diversity and distribution and support management needs of the Rose Atoll Marine National Monument. From a geological standpoint, Rose Atoll is thought to be an older seamount linked to the Cook-Austral Islands instead of Samoa. Malulu to the west (to be sampled in a later dive during this cruise) and Rose Atoll are key in defining the Cook-Austral hotspot tracks back in time, and as such an age on a volcanic rock is needed from Rose Atoll. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano.

"Governor Lolo" Seamount (formerly "Seamount D")

Area

"Governor Lolo" Seamount (formerly "Seamount D"); Samoan region, eastern portion of Am. Samoa EEZ

Overview

Date:	February 19, 2017
Max Depth:	439 Meters
Bottom Time:	n/a

Purpose

The dive was cancelled owing to inclement weather conditions.

"Leoso" seamount, ROV on bottom at 3770 m (-12.64986505, -167.27212505)

Area

"Leoso" seamount, ROV on bottom at 3770 m (-12.64986505, -167.27212505); North Samoan region, Near southern margin of Manihiki Plateau

Overview

Date:	February 20, 2017
Max Depth:	3771.8 Meters
Bottom Time:	2 Hours 49 Minutes 18 Seconds

Purpose

The goal of this dive was to generate baseline information on geology and geochemistry of this unexplored (and largely unmapped) seamount. There is also significant interest in understanding the deep sea habitats and biological communities on the seamount to better understand their diversity and distribution. Maps of the seamount were generated the night before. From a geological standpoint, this seamount may be an older seamount linked to the Society hotspot, not Samoa. Samples from this seamount are key in defining the Society hotspot tracks back in time, and as such an age on a volcanic rock is needed from this seamount. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano. From the biological perspective this dive has the potential to provide new depth records for several species as well the discovery of new species. Very little work has been done in the Central Pacific at these depths on seamounts. We aimed to collect information that will inform the biogeographic identity of the communities at abyssal depths in this region.

"Utu" seamount, ROV on bottom at ~3043 m

Area

"Utu" seamount, ROV on bottom at ~3043 m; North Samoan region, Near southern margin of Manihiki Plateau

Overview

Date:	February 21, 2017
Max Depth:	3037 Meters
Bottom Time:	4 Hours 38 Minutes 49 Seconds

Purpose

The goal of this dive was to generate baseline information on geology and geochemistry of this unexplored (and largely unmapped) seamount. There is also significant interest in understanding the deep sea habitats and biological communities on the seamount to better understand their diversity and distribution. Maps of the seamount were generated the night before. From a geological standpoint, this seamount may be an older seamount linked to the Society hotspot, not Samoa. Samples from this seamount are key in defining the Society hotspot tracks back in time, and as such an age on a volcanic rock is needed from this seamount. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano. From the biological perspective this dive has the potential to provide new depth records for several species as well the discovery of new species. Very little work has been done in the Central Pacific at these depths on seamounts. We aimed to collect information that will inform the biogeographic identity of the communities at abyssal depths in this region.

"Moki" seamount, ROV on bottom at ~2200 m

Area

"Moki" seamount, ROV on bottom at ~2200 m; North Samoan region, Near southern margin of Manihiki Plateau

Overview

Date:	February 22, 2017
Max Depth:	2116.3 Meters
Bottom Time:	3 Hours 34 Minutes 37 Seconds

Purpose

The goal of this dive was to generate baseline information on geology and geochemistry of this unexplored (and largely unmapped) seamount. There is also significant interest in understanding the deep sea habitats and biological communities on the seamount to better understand their diversity and distribution. Maps of the seamount were generated the night before. From a geological standpoint, this seamount may be an older seamount linked to the Society hotspot, not Samoa. Samples from this seamount are key in defining the Society hotspot tracks back in time, and as such an age on a volcanic rock is needed from this seamount. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano. From the biological perspective this dive has the potential to provide new depth records for several species as well the discovery of new species. Very little work has been done in the Central Pacific at these depths on seamounts. We aimed to collect information that will inform the biogeographic identity of the communities at abyssal depths in this region.

Deeper dive on "Utu" seamount

Area

Deeper dive on "Utu" seamount; North Samoan region, Near southern margin of Manihiki Plateau

Overview

Date:	February 23, 2017
Max Depth:	3931.9 Meters
Bottom Time:	3 Hours 52 Minutes 24 Seconds

Purpose

The goal of this dive was to generate baseline information on geology and geochemistry of this unexplored (and largely unmapped) seamount. There is also significant interest in understanding the deep sea habitats and biological communities on the seamount to better understand their diversity and distribution. Maps of the seamount were generated two days before this dive for preparation for the first dive on this seamount; the first dive (Dive 6) was in the crater on the summit of the seamount. This dive (Dive 8) targets the deeper flanks of the volcano, and focuses on the the volcanic platform upon which the volcano is constructed. From a geological standpoint, this seamount may be an older seamount linked to the Society hotspot, not Samoa. Samples from this seamount are key in defining the Society hotspot tracks back in time, and as such an age on a volcanic rock is needed from this seamount. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano. From the biological perspective this dive has the potential to provide new depth records for several species as well the discovery of new species. Very little work has been done in the Central Pacific at these depths on seamounts. We aimed to collect information that will inform the biogeographic identity of the communities at abyssal depths in this region.

"Vailulu'u" seamount crater

Area

"Vailulu'u" seamount crater; Eastern Samoan region

Overview

Date:	February 24, 2017
Max Depth:	928.5 Meters
Bottom Time:	8 Hours 22 Minutes 26 Seconds

Purpose

The goal of this dive was to explore the volcanically active crater of Vailulu'u seamount. The dive planned to target a location previously know to be the locus of hydrothermal venting, which is located near a plume in the water column (extending above the crater) that was detected to emanate for a region of the crater that is near the site of previously-observed hydrothermal venting. There is also significant interest in understanding the deep sea habitats and biological communities associated with the hydrothermal activity and the hardsubstrate areas on the volcano to better understand their diversity and distribution. From a geological standpoint, this seamount is volcanically active and is likely the youngest volcano in the Samoan region. Therefore, further data on this seamount provides a critical window into the geochemistry and volcanology of the early stages of the evolution of a Samoan volcano. From the biological perspective this dive provides information about the successional changes in the biological communities associated with changes in the environmental setting product of active volcanism. We aim to collect information that will inform the biogeographic identity of the hydrothermal and hardsubstrate communities at bathyal depths in this region.

Rose Atoll (shallow dive on east flank)

Area

Rose Atoll (shallow dive on east flank); Eastern Samoan region (easternmost island in American Samoa)

Overview

Date:	February 25, 2017
Max Depth:	678.4 Meters
Bottom Time:	6 Hours 47 Minutes 35 Seconds

Purpose

The goal of this dive was to generate baseline information on deep biological communities, including bottom fish and precious corals habitats, to better understand their diversity and structure with the goal of supporting management needs of the Rose Atoll Marine National Monument. The dive began around 700 m deep on a prominent ridge extending from the eastern region of the Rose Atoll, as shown in the bathymetry map. We started on the ridge crest, and then continued moving upslope to a depth of ~250 m. From a geological standpoint, Rose Atoll is thought to be an older seamount linked to the Cook-Austral Islands instead of Samoa. Malulu to the west (to be sampled in a later dive during this cruise) and Rose Atoll are key in defining the Cook-Austral hotspot tracks back in time, and as such an age on a volcanic rock is needed from Rose Atoll. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano.

"Governor Lolo" Seamount (formerly referenced as "Seamount D")

Area

"Governor Lolo" Seamount (formerly referenced as "Seamount D"); Eastern American Samoa EEZ

Overview

Date:	February 26, 2017
Max Depth:	3005.3 Meters
Bottom Time:	4 Hours 6 Minutes 55 Seconds

Purpose

The goal of this dive was to generate baseline information on geology and geochemistry of this unexplored (and largely unmapped) seamount. There was also significant interest in understanding the deep sea habitats and biological communities on the seamount to better understand their diversity and distribution. American Samoa's Division of Marine and Wildlife Resources have expressed an interest in the seamounts in this region as long-line fishing activities are conducted in the area. From a geological standpoint, this seamount may be an older seamount linked to the Cook-Austral Islands, not Samoa. Samples from this seamount are key in defining the Cook-Austral hotspot tracks back in time, and as such an age on a volcanic rock is needed from this seamount. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano. From the biological perspective this dive had the potential to provide new depth records for several species as well the discovery of new species. Very little work has been done in the Central Pacific at these depths on seamounts. We aim to collect information that will inform the biogeographic identity of the communities at abyssal depths in this region.

Malulu seamount

Area

Malulu seamount; Eastern American Samoa (between Vailulu'u seamount and Rose atoll)

Overview

Date:	February 27, 2017
Max Depth:	2469.9 Meters
Bottom Time:	4 Hours 58 Minutes 11 Seconds

Purpose

The goal of this dive is to generate baseline information on deep sea habitats and biological communities, particularly deep-sea coral communities, to better understand their diversity and distribution and support management needs of the Rose Atoll Marine National Monument. Water column transects are also planned during this dive to obtain information on animals living in the largest unexplored biome on the planet. The dive will begin around 2500 m, near the summit of Malulu seamount, as shown in the bathymetry map. The ROV will climb to the summit and then continue moving along the flat top of the summit. After the ROV comes off bottom at approximately 2430m, the ROV will ascend to 2000 m to start the water column exploration portion of the dive. A 10-minute transect will be conducted at each of the following depths, while moving the ROV at 0.1 knots: 2000m, 1500m, 1200m, 900m, 700m, 500m and the depth of the scattering layer identified in EK60 data. The EK60 sonar will be on for the duration of these transects, and the 38 kHz ADCP will also be run if it does not cause interference. From a geological standpoint, Malulu seamount is thought to be an older seamount linked to another, non-Samoa hotspot. Rose Atoll to the east (sampled in an earlier dive during this cruise) and Malulu seamount are key in defining the Cook-Austral hotspot tracks back in time, and as such an age on a volcanic rock is needed from Malulu seamount. Without an age, it is not possible to truly define plate motion for the time frame represented by this volcano.

Tutuila (Nautilus dive)

Area

Tutuila (Nautilus dive); American Samoa (south side of Tutuila, near Pago Pago harbor)

Overview

Date:	March 07, 2017
Max Depth:	460.7 Meters
Bottom Time:	6 Hours 12 Minutes 15 Seconds

Purpose

This dive sought to characterize a population of protected Nautili that has been observed using baited cameras in the Taena Bank area, at depths between 300 and 400 meters, near the harbor of Pago Pago, American Samoa. This is also the depth range for bottomfish and precious corals. From a geologic standpoint, this dive presented an important opportunity to sample the shallow volcanic stratigraphy of Tutuila island.