Okeanos Explorer (EX1202L2): Gulf of Mexico Exploration

Vessel: NOAA Ship Okeanos Explorer; Expedition Dates: March 19 - April 7, 2012

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

From March through April 2012, a team of scientists and technicians both at-sea and on shore (telepresence) set out to explore cold seeps, deep coral communities, undersea canyons, shipwrecks - and perhaps even mud volcanoes and brine pools. The expedition also marks the return of the Institute for Exploration's Little Hercules remotely operated vehicle (ROV) and NOAA's Seirios camera sled and lighting platform tethered to the NOAA Ship Okeanos Explorer. Primary areas of operations include the vicinity of the Deepwater Horizon site, Mississippi Canyon and Green Canyon and deepwater areas in the vicinity of the Flower Garden Banks.

Rocky Scarp #1

Area

Rocky Scarp #1; Northwestern Gulf of Mexico; ~150nm southwest of Tampa, Florida

Overview

Purpose

To explore the upper rocky scarp terrain and biology along features east of the West Florida Escarpment. This site represents the highest priority submitted by shore-side scientists, with the goal of exploring habitats associated with this shallow scarp feature (in comparison to the deeper West Florida Escarpment proper to be explored on subsequent dives). The desired dive track would start below this upper scarp and proceed transiting east upslope. The expectation is that we will encounter a large rocky wall on the scarp, with various attached fauna (including corals) as we traverse up and down the scarp to the south.

Shallow Ridge, W. Florida Escarpment

Area

Shallow Ridge, W. Florida Escarpment; Northwestern Gulf of Mexico; ~150nm southwest of Tampa, Florida

Overview

Purpose

To explore a shallow ridge that runs along the north-south direction, just west of the scarp. This site is 3.9 km to the SE of our first dive at Rocky Scarp, and is a prominent feature in our multibeam bathymetry data. The plan is to start the dive at the southern tip of the ridge, follow its western edge to the north, loop back from the east, and end the dive at where we started. This allows us to characterize the biology and geology of the ridge on its current facing side (west) and its lee side (east).

West Florida Escarpment Canyon

Area

West Florida Escarpment Canyon; Northwestern Gulf of Mexico; ~190nm west of Tampa, Florida

Overview

Purpose

To explore an area on a West Florida Escarpment Canyon at 27 degrees 54.84N 86 degrees 02.05W at a depth of 2100m, beginning at the base of the escarpment wall on the inward side of the canyon basin on sedimented slope near 2100m depth. The plan is to explore this sedimented region, the base of the escarpment and then progress up the face of the scarp to the top at about 1700m.

DeSoto Canyon 493

Area

DeSoto Canyon 493; Northwestern Gulf of Mexico; ~270nm west of Tampa, Florida

Overview

Purpose

The DeSoto Canyon escarpment region has not been well characterized. Past cruises discovered fauna here not found in other parts of the Gulf of Mexico, some were similar to those found in the Atlantic. This dive explored a possible seep site at the bottom of the escarpment, and moved towards possible hard substrate along the slope, identified from backscatter data.

DeSoto Canyon (DC) #673

Area

DeSoto Canyon (DC) #673; Northwestern Gulf of Mexico; ~260nm west of Tampa, Florida

Overview

Purpose

To explore a position south of the DeSoto Canyon (DC) in the lease block #673. Seep and coral communities have been reported in the region, based on two previous dives. We will explore the lithology or physical character of the seafloor starting on what we think is an apparent breakout of sediment or a slump over the escarpment, and then as we proceed upslope encounter the escarpment proper. We will explore the potential differences in fauna associated with these different substrates.

DeSoto Canyon 493 (West Facing Scarp)

Area

DeSoto Canyon 493 (West Facing Scarp); Northwestern Gulf of Mexico; ~275 nm northwest of Tampa, Florida

Overview

Purpose

The DeSoto Canyon escarpment region has not been well characterized. Past cruises discovered fauna here not found in other parts of the Gulf of Mexico, and some were similar to those found in the Atlantic. Today we will explore the west facing side of this escarpment to document its biology and geology, with waypoints at backscatter targets for soft sediment, and along the slope. The information gathered can be compared to the rest of the DeSoto Canyon escarpment and the rest of the Gulf of Mexico. This dive will also include mid water surveys for potential sperm whale prey items in the water column.

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Area

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Overview

Purpose

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DeSoto Canyon Dragon Head

Area

DeSoto Canyon Dragon Head; Northwestern Gulf of Mexico; ~250nm northwest of Tampa, Florida

Overview

Purpose

The DeSoto Canyon region is characterized by flat sedimented area at its uppermost tip. Our bathymetric data showed a single, 600 m long, 100 m tall, mound here with strong backscatter signal suggesting hard grounds. Today's dive will explore this hill, characterize its geology and fauna, and to ground truth the bathymetric and backscatter data.

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Area

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Overview

Purpose

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Area

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Overview

Purpose

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Mississippi Canyon MC294/338

Area

Mississippi Canyon MC294/338; Northwestern Gulf of Mexico; ~325nm northwest of Tampa, Florida (vicinity of Deepwater Horizon)

Overview

Purpose

The timing of today's dive is critical to a substantial effort by NOAA and other parties to track changes over time at a site in lease block MC294. We will explore and image corals growing on hard substrate for changes since previous visits in 2010 and 2011. Today's exploration in the time domain will be a wonderful complement to the work that we have be doing on this cruise.

Mississippi Canyon 297

Area

Mississippi Canyon 297; Northwestern Gulf of Mexico; ~315nm northwest of Tampa, Florida

Overview

Purpose

The timing of today's dive is critical to a substantial effort by NOAA and other parties to track changes over time at a site in lease block MC297. We will explore and image corals growing on hard substrate for changes since a previous visit in 2011. Today's exploration in the time domain will be a wonderful complement to the work that we have be doing on this cruise.

Mississippi Canyon 388

Area

Mississippi Canyon 388; Northwestern Gulf of Mexico; ~300nm northwest of Tampa, Florida (vicinity of Deepwater Horizon)

Overview

Purpose

To launch the vehicles on a study location in Mississippi Canyon lease block 388. This site was discovered during a towed camera and AUV Sentry surveys, and then visited with Alvin in December 2011. It has both seep communities and coral communities distributed over a fairly large area. Multibeam data and 3D seismic data for the area suggests that coral will be much more widespread at this site. The purpose of revisiting this location is to explore and characterize these coral ecosystems, and explore for additional seep and coral communities.

Mississippi Canyon 255

Area

Mississippi Canyon 255; Northwestern Gulf of Mexico; ~310nm northwest of Tampa, Florida (vicinity of Deepwater Horizon)

Overview

Purpose

To explore two regions of strong 3D seismic signal from past surveys. One is on the bottom, the other on the top edge of a salt dome in the MC 255 lease block. The moderate to strong signals suggest possible hard grounds that could host coral colonies. We will start from the bottom of the salt dome and explore up its slope, documenting the biology and geology here.

Mississippi Canyon 036

Area

Mississippi Canyon 036; Northwestern Gulf of Mexico; ~310nm northwest of Tampa, Florida (vicinity of Deepwater Horizon)

Overview

Purpose

Today's dive will explore possible hardgrounds, identified by a previous survey by the AUV Sentry, in the MC036 region in the Mississippi Canyon. In addition, we will briefly revisit two sites in this area with corals previously documented as part of the effort to determine extent and intensity of the Deepwater Horizon oil spill.

Salt Dome Seep Target

Area

Salt Dome Seep Target; Northwestern Gulf of Mexico; ~300nm northwest of Tampa, Florida

Overview

Purpose

The goal of this exploratory dive is to groundtruth bubble stream observations in EX multibeam by locating the seafloor source location of these bubbles, and ultimately seep environments. In addition, the acoustic backscatter of this area contains high reflectivity, and as such may also provide hard ground habitats for exploration. We will also explore the mid-water column during descent, running for 10 minute intervals at 600, 700, 800, 900, and 1000 meters. Our bottom target depth is 1100 meters. Once on bottom, we will move upslope searching for seafloor sources of methane bubbles. We will begin with an on bottom position downslope 150m south of the target area.