Okeanos Explorer (EX1605L1): CAPSTONE CNMI & Mariana Trench MNM (ROV & Mapping)

Vessel: NOAA Ship Okeanos Explorer; Expedition Dates: April 20 - May 11, 2016

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

The ship will conduct 24 hour operations consisting of daytime ROV dives and evening/nighttime mapping operations including during transit. During this cruise we will conduct primarily 8 hour ROV dives with occasional 10 or 12 hour dives on particularly interesting or deep water dive sites, as staffing allows. ROV operations will focus in depths between 250 and 6,000 meters and will include high-resolution visual surveys and limited sample collection. Mapping operations will be conducted in 250 m of water and deeper, and include transit and overnight multibeam, water column backscatter, and sub-bottom data collection. Opportunistic CTD rosette operations may be requested to collect more information about the environmental parameters at ROV dives sites, or opportunistically at selected sites where collecting the data is considered important to understanding the physical or chemical properties of the overlying water column.

Santa Rosa North

Area

Santa Rosa North; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive was on a pinnacle feature located on Santa Rosa Reef south of Guam where it explored for high-density communities of deep-sea corals, in this case precious corals that are under the management of NOAA Fisheries. While the precious coral fishery is listed as a managed fishery in Guam and CNMI, no precious coral beds have been identified to date and only anecdotal accounts have been published of their presence in this region of the Pacific. This dive also surveyed bottom-fish fishery habitat, which had not been previously characterized in Guam/CNMI. The purpose was to determine if there was a depth and site overlap between the two fisheries.

Santa Rosa South

Area

Santa Rosa South; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive was on a ridge feature located at site called Santa Rosa South where the goal was to explore for high-density communities of deep-sea corals, in this case precious corals that are under the management of NOAA Fisheries. While the precious coral fishery is listed as a managed fishery in Guam and CNMI, no precious coral beds have been identified to date and only anecdotal accounts have been published of their presence in this region of the Pacific. This particular site was chosen to also survey bottom-fish fishery habitat, which has also not been characterized in Guam/CNMI and determine if there is a depth and site overlap between the two fisheries.

Sirena Canyon

Area

Sirena Canyon; North Pacific Ocean; Southern Marianas

Overview

Purpose

The objective of this dive was to observe the biology and geology in the deeper parts of the MTMNM along the side of a broad canyon that drops into the Sirena Deep - one of the deepest locations in the trench. Within the monument, little work has been done between 5000 and 8000 m. However, there has been more sampling in deeper areas e.g. at seep and mud volcano sites, and also at deep sites such as the Challenger Deep. Therefore, the dive track began at 4983 m and moved ~700 m in distance up steep topography to the west where the dive ended at 5865 m.

Enigma Seamount

Area

Enigma Seamount; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive will explore a seamount that may lie on a boundary between the Pacific Plate and a younger tectonic plate. The seamounts aligned along a NNW-SSE trend may denote the plate boundary and this seamount group is currently seismically active. Rock samples collected on this dive could be dated and would help to determine whether in fact the seamounts are younger than the adjacent Jurassic Pacific Plate or not. We plan to begin the dive at WP1 (depth 3778 m), and proceed up slope to the south for 800 m over the steeper slopes that would be more likely to reveal in situ exposures of rock. Ending depth is planned at ~3550 m.

Fina Nagu Caldera D

Area

Fina Nagu Caldera D; North Pacific Ocean; Southern Marianas

Overview

Purpose

The Fina Nagu Volcanic Chain is poorly studied, and none of its calderas, until this dive, had been imaged for signs of hydrothermal activity or biological communities. Based on the location of our dive, we think that volcanic activity would increases northward through the calderas but are unsure. Fina Nagu D was expected to have some mature biology communities, but little biology was seen. This dive began at 3029 m, and traversed 750 m upslope to the north, ending at a depth of 2692 m.

Fina Nagu Caldera C

Area

Fina Nagu Caldera C; North Pacific Ocean; Southern Marianas

Overview

Purpose

The Fina Nagu Volcanic Chain is poorly studied, and none of its calderas, until this dive, had been imaged for signs of hydrothermal activity or biological communities. Based on the location of our dive, it was hypothesized that volcanic activity would increase northward through the calderas but are unsure. Fina Nagu C was expected to have some mature biology communities, but little biology was seen. This dive began at 2689 m, and traversed 670 m upslope to the north, ending at a depth of 2637 m.

Fina Nagu Caldera A

Area

Fina Nagu Caldera A; North Pacific Ocean; Southern Marianas

Overview

Purpose

The Fina Nagu Volcanic Chain is poorly studied, and none of its several calderas have been examined by ROV or manned submersible for signs of hydrothermal activity or biological communities. Based on location, we thought that volcanic activity would increase northward but are not sure. Fina Nagu A is the most likely of the chain to harbor hydrothermal activity. This dive was planned to begin at 2321 m and to traverse 760 m upslope to the west, ending at a depth of 2234 m.

NW Guam Seamount

Area

NW Guam Seamount; North Pacific Ocean; Southern Marianas

Overview

Purpose

This extinct arc volcano is the last unexplored large arc seamount in the southern Marianas. Its summit region was expected to host extinct hydrothermal fields and mature summit communities, including fisheries. This dive was planned to begin at 1349 m, and to traverse 486 m upslope to the south, with the goal to reach the seamount summit (1198 m) and then explore along the summit.

Young Lava Flows

Area

Young Lava Flows; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive explored a series of recent (2013-2015) lava flows and searched for hydrothermal vents or diffuse flow on the young lavas. Biology inhabiting the area was noted. The dive began at a depth of 4066 m, and moved south from pillow mound to mound for ~700 m (if possible), ending at a depth of 4055 m.

New Hydrothermal Vent Field 1

Area

New Hydrothermal Vent Field 1; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive explored an area mapped with the Sentry AUV in December 2015 while searching for new hydrothermal vents on the seafloor The dive targets were suspected to be high-temperature black smoker chimneys. We planned to document animals living at and near the vents. The dive was planned to begin at an approximate depth of 3860 m, and move from north to south for ~640 m, ending at a slope whose bottom depth was 3923 m.

New Hydrothermal Vent Field 2

Area

New Hydrothermal Vent Field 2; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive explored an area mapped with the Sentry AUV in December 2015 during a search for new hydrothermal vents on the seafloor (probably high-temperature black smoker chimneys). If vents were found, we planned to document animals living at and near the vents. The dive was planned to begin at a depth of 3292 m, and move from west to east for a total of ~600 m, ending at a depth of 3288 m.

Zealandia Bank

Area

Zealandia Bank; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive will be on Zealandia Banks to explore for high-density communities of deep-sea corals, in this case precious corals that are under the management of NOAA Fisheries. While the precious coral fishery is listed as a managed fishery in Guam and CNMI, no precious coral beds have been identified to date and only anecdotal accounts have been published of their presence in this region of the Pacific. This particular site was chosen to also survey bottomfish fishery habitat, which has also not been characterized in Guam/CNMI and determine if there is a depth and site overlap between the two fisheries.

Kunanaf Hulo Seamount (Mud Volcano)

Area

Kunanaf Hulo Seamount (Mud Volcano); North Pacific Ocean; Southern Marianas

Overview

Purpose

The edifice is very similar in morphology to other serpentinite mud volcanoes on the Mariana Forearc. It had never been dived on, and lies farther from the trench axis (thus a proxy for greater depth to the top of the subducting Pacific Plate) than nearby mud volcanoes that had been sampled. Active springs on these seamounts are known to have chimneys of carbonate and/or brucite. The morphology of chimney structures and their composition changes with distance from the trench at the springs. There are benthic animals at active springs and the sidescan show high backscatter that indicates a rough seafloor. Obtaining subbottom profiles would be very useful for determining if there are thick or thin mudflows on the summit area of this edifice. Usually there are thinner flows near active springs, but some mudflows appear to be voluminous and cover up to a half of the edifice flank. The dive track was planned to begin at 3685 m and to move along the crest for 650 m to a depth of 3675 m.

Pigafetta Guyot

Area

Pigafetta Guyot; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive was on Pigafetta Guyot, a Cretaceous seamount just to the east of the trench. The dive's objectives were to explore for high-density communities of deep-sea corals and sponges and do an initial characterization of Mn-crust habitats on one of the presumed oldest seamounts on the Pacific plate. The dive was planned to begin at a depth of 2045 m and to move along the ridge to the S-SW for ~725 m, to a depth of 2010 m.

Enrique Guyot

Area

Enrique Guyot; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive was on Enrique Guyot, a Cretaceous seamount just to the east of the trench. The dive had objectives that included exploring for high-density communities of deep-sea corals and sponges and doing an initial characterization of Mn-crust habitats on one of the presumed oldest seamounts on the Pacific plate. The dive was planned to begin at a depth of 2360 m and to move up along the ridge to the S-SW for ~725 m, to a depth of 2010 m.

Del Cano Guyot

Area

Del Cano Guyot; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive was on Del Cano Guyot, a Cretaceous seamount just to the east of the trench and right on the boundary of the Monument. The dive had objectives that included exploring for high density communities of deep-sea corals and sponges and doing an initial characterization of Mn-crust habitats on one of the presumed oldest seamounts on the Pacific plate. The dive was planned to begin at a depth of 1880 m and move along the ridge to the south for 635 m, to a depth of 1845 m.

Farallon de Menidilla

Area

Farallon de Menidilla; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive was on the slope of Farallon de Medinilla (FDM) to explore for high density communities of deep-sea corals, in this case precious corals that are under the management of NOAA Fisheries. While the precious coral fishery is listed as a managed fishery in Guam and CNMI, no precious coral beds have been identified to date and only anecdotal accounts have been published of their presence in this region of the Pacific. This particular site was chosen to also survey bottomfish fishery habitat, which has also not been characterized in Guam/CNMI and to determine if there is a depth and site overlap between the two fisheries. The dive was planned to begin at a depth of 500 m and to move upslope to the SE for ~700 m to a depth of 250 m.

(North) Esmerelda Bank

Area

(North) Esmerelda Bank; North Pacific Ocean; Southern Marianas

Overview

Purpose

This dive explored for high-density communities of deep-sea corals, in this case precious corals that are under the management of NOAA Fisheries on the slope of Esmeralda Bank. While the precious coral fishery is listed as a managed fishery in Guam and CNMI, no precious coral beds have been identified to date and only anecdotal accounts have been published of their presence in this region of the Pacific. This particular site was chosen to also survey bottomfish fishery habitat, which has also not been characterized in Guam/CNMI and determine if there is a depth and site overlap between the two fisheries. The dive is planned to begin at 537 m, move along track for ~640 m, and end at a depth of 300 m.

Esmerelda Crater and East Flank

Area

Esmerelda Crater and East Flank; North Pacific Ocean; Southern Marianas

Overview

Purpose

Esmeralda Bank is an active volcano and almost certainly has vents in its central crater. According to Pacific Islands Benthic Habitat Mapping Center, the Bank appears to have experienced recent volcanic activity and shows signs of current hydrothermal circulation. Previous NOAA ROV dives in 2004 have been blocked by thick "smoke"; we decided to try to dive to see what is there. The preferred dive track is in the crater, beginning at 338 m, moving through the crater and up the ridge for ~ 660 m, ending at a depth of 262 m. The alternate track begins at 436 m, goes upslope for ~660 m, and ends at a depth of 247 m.