Okeanos Explorer (EX1402L3): Gulf of Mexico Mapping and ROV Exploration

Vessel: NOAA Ship Okeanos Explorer; Expedition Dates: April 10 - May 1, 2014

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

Okeanos Explorer cruise EX1402 leg 3 - the final voyage in the series of three ocean exploration cruises as part of the 2014 Gulf of Mexico Expedition - conducted 16 highly successful telepresence-enabled remotely operated vehicle (ROV) dives in two different areas of the Gulf: The northwestern part of the basin, characterized by a very thick (~12-14 kilometer) accumulation of sediments mobilized from below by evaporites/salt, and the central part of the Florida Escarpment, the western edge of a thick carbonate platform, and the outer shelf next to it. Dive 1 was conducted on April 12, and Dive 16 was conducted on April 29. One dive was sacrificed to inclement weather in the first area, and another in the second area could not be conducted because of strong currents and winds. All of these dives were identified by management groups or support management interests in the region. During the course of these dives, our initial count is that more than 230 different types of animals were documented. Northwestern Gulf of Mexico Dives ROV dives were conducted at a diversity of sites. In the northwestern Gulf of Mexico, dives were conducted at two cold seep sites, two deep-sea coral habitat areas of interest for deep-sea coral modeling, three historic shipwrecks (investigated during two dives), three sites in Keathley Canyon, two sites in Bryant Canyon, and two asphalt volcanoes. Highlights of these dives include discovery of asphalt volcanism (nicknamed "tar lilies") in an area of the Gulf where it was not previously known to occur; discovery of a chronometer (a rare and significant finding for an early 19th century vessel) at Monterrey wrecksite A; and possible extension of the depth range of a few deep-sea coral types in the Gulf of Mexico. Several rare observations also occurred, including Paleodictyon "burrows" in Keathley canyon; a rare orange sea star, Dytaster sp., in Bryant Canyon; and a dumbo octopus displaying a body posture that has never before been observed in cirrate octopods. West Florida Escarpment Dives Four ROV dives were also conducted at priority sites on the central part of the West Florida Escarpment, including two dives investigating seafloor habitats in deep water along the escarpment and two dives documenting deep-sea coral habitat in high-priority areas for fisheries management on the shelf. Highlights from these dives included incredible deep-sea coral diversity (at least 23 species) during one of the deep escarpment dives; discovery of two potential new species of crinoids; and close-up imagery documenting a sea urchin eating an octocoral - an observation rarely, if ever, captured on camera. Mission Participation and Reach More than 70 scientists and students participated in these dives from shore, providing their input and expertise to help characterize these areas and guide the exploration. Online coverage of the expedition including live video feeds, were streamed to shore throughout, allowing hundreds of thousands of the public to join our dives and virtually explore the ocean with us! The expedition was highlighted and shared on more than 150 different media venues in the U.S. and Europe, and the live video feeds received more than 700,000 visits during leg 3. Through social media venues and our website's "Ask an Explorer" link, a tremendous number of comments have been shared by the public, expressing excitement about deep ocean observations and thanking the expedition team for allowing them to "dive" with us.

GB648

Area

GB648; Gulf of Mexico

Overview

Purpose

Dive 1 of EX1402 L3 succeeded in achieving the two primary geological objectives set forward by the nominating organization - the Bureau of Ocean Energy Management (BOEM): 1) ascertaining whether high acoustic backscatter (from multibeam bathymetry) and linked high seafloor reflectivity (from 3D seismic/industry data) correlate with hardgrounds, and 2) determining whether seafloor locations of presumed cold seeps as deduced from the origination of ~vertical bubble stream anomalies in the overlying water column (from multibeam bathymetry) are discrete sites of gas escape. Both turned out to be true.

GB907

Area

GB907; Gulf of Mexico

Overview

Purpose

The geological objectives of dive 2, the second dive proposed by the Bureau of Ocean Energy Management (BOEM), involved: Both objectives were confirmed. the search for cold seeps, escape of bubbles/oil from the seafloor as indicated by multibeam bathymetry "bubble stream anomalies", and confirmation that high backscatter returns from the bathymetric high/ridge on which this dive was conducted correlated with (carbonate) hardgrounds on or near the seafloor. Both objectives were confirmed.

NW Gulf Mid-Depth

Area

NW Gulf Mid-Depth; Gulf of Mexico

Overview

Purpose

The third dive concentrated on assessing mid-water coral habitats, by examining first the ~30 degree slope, then part of the crest, of a ~100 m high topographic high (part of a sinuous ridge) in depths of ~1150-1050 m. The dive was nominated by Brian Kinlan of NOAA's NCCOS, Center for Coastal Monitoring and Assessment. This dive represents the first of multiple dives designed to quantify models of deep-water coral habitats in the Gulf of Mexico.

Keathley Canyon Site KC2

Area

Keathley Canyon Site KC2; Gulf of Mexico

Overview

Purpose

Dive 4 was designed as a transect from the west side of the thalweg (main channel) of Keathley Canyon, in ~2,000 m, across that thalweg and upward, across two west-facing slopes and an intervening bench. The dive ended near the top of that longer second slope, in ~1760 m.

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Area

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Overview

Purpose

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Keathley Canyon KC3

Area

Keathley Canyon KC3; Gulf of Mexico

Overview

Purpose

This Keathley Canyon dive site was ~20 km south of dive 4 in the same drainage system. This dive was nominated by Brian Kinlan/Bill Keine. The distribution and abundance of black and bamboo corals was the stated biological priority.

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Area

n/a; n/a

Overview

Purpose

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Keathley Canyon UTIG

Area

Keathley Canyon UTIG; Gulf of Mexico

Overview

Purpose

This dive was nominated by the University of Texas, Institute for Geophysics. The focus was the westward-facing slope near the deep-water entrance to Keathley Canyon. Objectives included looking for evidence for brine escape at the seafloor, based upon subsurface seismic evidence for rising salt beneath this slope. The vehicles landed on a slight westward-facing slope at a water depth of 2,655 m, on rippled soft sediment. Until the last 15-20 min of the dive, the bottom was characterized by this type of sedimented seafloor; ripples, consistently suggesting intermittent downslope/down-canyon currents, were often present. The vehicles transited ~2.4 km over the course of the ~5.3 hr. dive, up a ~11 degree slope, across a flat bench at ~2,500 m of water, then up another ~11 degree slope until the end of the dive, at ~2,266 m of water.

Bryant Canyon Shallow

Area

Bryant Canyon Shallow; Gulf of Mexico

Overview

Purpose

Dive 9 was the first of two dives along the flanks of Bryant Canyon, the easternmost of the three large drainage systems characterizing the north-central Gulf of Mexico. This dive, to examine a ridge along the "shallow" eastern flank of the Canyon, was slated for water depths of ~2,600-2,400 m. The dive was nominated by Tim Shank (WHOI) and Brian Kinlan (NOAA). The primary objective was to characterize deep-water coral habitats, and associated geologic environments.

Bryant Canyon Deep

Area

Bryant Canyon Deep; Gulf of Mexico

Overview

Purpose

This dive consisted of two parts: mid-water examinations at discrete depths for pelagic flora and fauna on descent, and a "deep-water" transect up the western wall of Bryant Canyon. The pelagic transect was nominated by Mike Vecchione of the Smithsonian Institution, and the seafloor dive was nominated by Tim Shank (WHOI) and Brian Kinlan (NOAA). The latter was designed to investigate potential deep-water coral habitats associated with seismic anomalies from BOEM and high backscatter areas registered by multibeam bathymetric data.

NW Gulf Deep

Area

NW Gulf Deep; Gulf of Mexico

Overview

Purpose

The focus of this dive was part of the wall of the Sigsbee Escarpment, from water depths of ~2,900-2,700 m. This dive was nominated by Brian Kinlan (NOAA) as true exploration. The primary goal was to characterize deep-water coral habitat, but the overall objective was to observe linked geologic and biological environments in a heretofore unvisited part of the Gulf of Mexico basin.

WR0325

Area

WR0325; Gulf of Mexico

Overview

Purpose

The primary objective of the dive was to investigate a ~60 m-long sidescan acoustic target, acquired using an industry AUV, composed of two parts with ~5 m seafloor relief, which suggested a shipwreck. This dive was nominated by personnel from the Bureau of Ocean Energy Management (BOEM) and archaeologists from NOAA.

Large Mound Deep

Area

Large Mound Deep; Gulf of Mexico

Overview

Purpose

The primary objective of this dive, up the wall of a prominent salient of the central part of the West Florida Escarpment, was to assess coral habitats, along with any other biology observed (see summary below). The dive was nominated primarily by Brian Kinlan and Peter Etnoyer (NOAA).

Many Mounds Deep

Area

Many Mounds Deep; Gulf of Mexico

Overview

Purpose

The objective of this second deep dive, from ~2100-1800 m, on the central part of the West Florida Escarpment in an overlapping but shallower depth range than Dive 13, was to complement that dive in quest to characterize deep-water coral habitats. The dive was nominated by Brian Kinlan and Peter Etnoyer (NOAA).

Many Mounds South Shallow

Area

Many Mounds South Shallow; Gulf of Mexico

Overview

Purpose

The primary objectives of this shallow (~550 m throughout) dive were to characterize: 1) Lophelia and black coral associations on top of a number of mounds/bioherms known to occur in this vicinity and 2) to focus on golden crab occurrences in the vicinity of these corals. The dive was nominated as one of a series of dives in these water depths by Brian Kinlan and Peter Etnoyer (NOAA) and a team from CIOERT and Harbor Branch led by John Reed (and including Stephanie Farrington).

Many Mounds South Shallow

Area

Many Mounds South Shallow; Gulf of Mexico

Overview

Purpose

Dive 16 took place north of Dive 15, in a similar water depth range (~550-470 m). The objectives were the same as Dive 15, to characterize: 1) Lophelia and black coral associations on top of a number of mounds/bioherms known to occur in this vicinity and 2) to focus on golden crab occurrences in the vicinity of these corals. The dive was nominated as one of a series of dives in these water depths by Brian Kinlan and Peter Etnoyer (NOAA) and a team from CIOERT and Harbor Branch led by John Reed (and including Stephanie Farrington).