Okeanos Explorer (EX2306): Seascape Alaska 5: Gulf of Alaska Remotely Operated Vehicle Exploration and Mapping

Vessel: NOAA Ship Okeanos Explorer; Expedition Dates: August 23 - September 16, 2023

Project Principals: Samuel Candio, NOAA/OAR/OER (Expedition Coordinator)

From August 23rd - September 14th, 2023 (Kodiak, Alaska to Seward, Alaska), NOAA Ocean Exploration conducted Seascape Alaska 5: Gulf of Alaska Remotely Operated Vehicle Exploration and Mapping (EX2306), a remotely operated vehicle (ROV) and mapping expedition to the Gulf of Alaska. Operations during this 23-day expedition included the completion of 19 successful remotely operated vehicle (ROV) dives, which were conducted in water depths ranging from 253.1 m to 4261.5 m for approximately 87 hours of bottom time and resulted in the collection of 383 samples. EX2306 also collected more than 28,000 sq. km of seafloor bathymetry and associated water column data using an EM 304 multibeam sonar. All data associated with this expedition will be archived within 120 days of the end of the expedition and will be publicly available through the NOAA Archives.

Kodiak Slope

Area

Kodiak Slope; Gulf of Alaska

Overview

Purpose

Investigate potential landslide deposits on the slope off of Kodiak.

Kodiak Seep

Area

Kodiak Seep; Gulf of Alaska

Overview

Purpose

To dive on a previously observed seep in a water depth of approximately 4400 m.

Giacomini Seamount

Area

Giacomini Seamount; Gulf of Alaska

Overview

Purpose

To explore the northern summit of Giacomini Seamount.

Quinn Seamount

Area

Quinn Seamount; Gulf of Alaska

Overview

Purpose

To dive on Quinn Seamount, one of the volcanoes in the Kodiak-Bowie seamount chain that has not been previously explored.

Surveyor Seamount

Area

Surveyor Seamount; Gulf of Alaska

Overview

Purpose

To explore and characterize a previously unknown cone-shaped mound on the summit plateau of Surveyor Seamount.

Durgin Guyot

Area

Durgin Guyot; Gulf of Alaska

Overview

Purpose

To dive on Durgin Guyot, another of the volcanoes in the Kodiak-Bowie seamount chain that has not been previously explored.

Deep Discoverer Dome

Area

Deep Discoverer Dome; Gulf of Alaska

Overview

Purpose

To target one of a number of enigmatic small seamounts present in the Gulf of Alaska that are on the order of 10 km across and several hundred meters high that may be small volcanic vents or mud volcanoes.

Denson Seamount

Area

Denson Seamount; Gulf of Alaska

Overview

Purpose

To dive on the northern side of Denson seamount, starting at a depth of about 1300 meters and working up to the summit plateau.

Ernest Sound

Area

Ernest Sound; Gulf of Alaska

Overview

Purpose

To evaluate an area modeled to have a potential high probability of presence and/or abundance of primnoid corals, and evaluate the rocky habitat in this glacially carved canal.

Behm Canal

Area

Behm Canal; Gulf of Alaska

Overview

Purpose

Areas close to the dive site have been highlighted in a set of species distribution models published by Rooper et al in 2017 as having a high probability of presence and/or abundance of primnoid corals, as well as other coral species captured during trawl surveys. This dive provides an excellent opportunity to document if the coral abundance is high, and inform future coral distribution models using image-based surveying.

Cordova Bay

Area

Cordova Bay; Gulf of Alaska

Overview

Purpose

To help assess the primnoid coral distribution and abundance model published by Rooper et al in 2017, and to evaluate the rocky habitat in this glacially carved canal.

Noyes Canyon

Area

Noyes Canyon; Gulf of Alaska

Overview

Purpose

Exploration of the walls of this canyon will provide a unique look at the rocks that underlie the shelf, which may form a distinct habitat at sub-shelf depths compared to the post-glacial sediments that are exposed outboard of the shelfbreak. Extensive bycatch of gorgonian coral, black, and hydro corals as well as unidentified and glass sponges has been observed in this area at depths of 300-1200 m. It is thought that corals and sponges are likely to be found in these steeper areas, which are not effectively sampled with traditional methods.

Prinsendam

Area

Prinsendam; Gulf of Alaska

Overview

Purpose

To investigate a target identified in the multibeam backscatter data that could potentially be the MS Prinsendam, a cruise liner that sank in 1980.

Chatham Seep

Area

Chatham Seep; Gulf of Alaska

Overview

Purpose

Chatham Seep provides a look at a cold seep site, with the potential for chemosynthetic fauna or megafauna associated with carbonate rock formations.

Middleton Canyon

Area

Middleton Canyon; Gulf of Alaska

Overview

Purpose

This is a geologically complex area at the intersection of the subduction zone and the Yakutat Terrane, where the sedimentary cover of the Yakutat Terrane is being accreted to the North American Plate and its oceanic basement is subducting underneath southern Alaska. This is a virtually unexplored area and the rocks potentially encountered encompass a wide variety of potential lithologies and structures. Due to the rocky outcrops known in the area and the target depth (>1000m), trawl and long line surveys have generally avoided this area, leaving a large data gap on the species that occur there. Diving on this site and documenting the fish species, habitat-forming species, associated fauna, and their relative abundances we see will aim to fill in this data gap to contribute to current fisheries research efforts in the Gulf of Alaska.

Bligh Island

Area

Bligh Island; Prince William Sound

Overview

Purpose

Biology, Geology

Storey Island

Area

Storey Island; Prince William Sound

Overview

Purpose

Visibility issues during Dive 16 resulted in a new location in Prince William sound being selected. The goal was to explore rocky habitat in Prince William Sound at depths of 250-400 m just to the northwest of Storey Island. There are very little data on the benthic fauna found deeper than 100 m in this area, so this dive aimed to fill in this data gap with observations and collections.

Gumby Ridge

Area

Gumby Ridge; Gulf of Alaska

Overview

Purpose

The dive site is an isolated ridge located on the mid-slope at depths of about 1650-1800 m on the Aleutian Subduction Zone, about 50 km southwest of Middleton Island. The ridge is one of many that lie on the middle and lower slope, inboard of the deformation front, that result from folding and faulting in the upper plate. Exploration of this ridge will provide information on the age and lithology of the sediments of the accretionary wedge, and the effects of severe shaking from large earthquakes. This is a geologic environment favorable for the formation of cold seeps, and may host active venting that would provide valuable information on subsurface fluid migration. Due to the target depth (>1000m), trawl and long line surveys have generally not reached this area, leaving a large data gap on the species that occur there. Diving on this site and documenting the fish species, habitat-forming species, associated fauna, and their relative abundances we see will aim to fill in this data gap to contribute to current fisheries research efforts in the Gulf of Alaska.

Lone Island

Area

Lone Island; Prince William Sound

Overview

Purpose

To explore rocky exposures in Prince William Sound at depths of 250-650 m east of Lone Island in Knight Island Passage. Bedrock exposures are expected to be Eocene and Paleocene volcanic rocks of the Orca Group. There is very little data on the benthic fauna found deeper than 100 m in this area, so we will aim to fill in this data gap with observations and collections.