Long Term Effects of the Deep-water Horizon Oil Spill

Completing the Lander Leg

Debbie Nail Meyer
Nov. 19 2012

R/V Falkor docked in Pascagoula at sunup Monday morning. The lander leg team offloaded the two giant landers with their carefully labeled data loggers. They packed assorted boxes of equipment and samples for shipment.

Hugs and handshakes were plentiful as eight departing scientists from the lander leg welcomed eight new team members coming onboard, and said goodbye to shipmates of the previous 16 days. Outgoing chief scientist Ian MacDonald, returning to Florida State University, welcomed the new chief scientist and old friend Chuck Fisher, from Pennsylvania State University. The emphasis of the research shifted from the soft muds and bubble plumes to the health of deep-sea corals that were in the path of the Deepwater Horizon disaster.

This cruise has already generated a lot of raw data. State-of-the-art 3DHD video and 18-megapixel still images filled terabyte hard drives. Some samples of water and sediment have gone ashore for rapid analysis; other material will remain in freezers aboard Falkor until the end of the cruise.

Turning raw data into finished tables and plots will require weeks or months of work. Ultimately the scientific conclusions will depend on the analytical results interpreted through the metadata—the indispensable records of when, where, and how the samples and observations were collected.

This continuing effort to quantify the effects of hydrocarbons on deep-sea habitats is a symbiosis between the Schmidt Ocean Institute and the research consortium ECOGIG (Ecosystem Impacts of Oil and Gas Inputs to the Gulf). In giving the ECOGIG teams use of R/V Falkor and ROV Global Explorer MK3, Schmidt Ocean Institute has supported research efforts that would not otherwise have been possible. Simultaneously, the ship and ROV teams have received valuable experience with science operations.

The shakedown cruise is a win-win effort as scientists gain access to the depths of the Gulf, while the Falkor’s crew put her equipment and systems through their paces.

Leg 1 Summary

To condense two intense weeks into a few sentences, the lander leg met challenges of weather, scheduling, and equipment issues, and unexpected discoveries to come through with solid accomplishments and the basis for important scientific results.

Sailing from Pascagoula on 6 November, rough weather forced curtailment of planned systems checks for the ROV Global Explorer MK3, but the team was still able to make vital collections of living corals from more than 450 meters depth as soon as the seas calmed. These specimens were kept alive for days and monitored in experimental exposures to determine effects of oil and dispersants.

Shifting to the Macondo area where the blowout occurred, the team used the ROV to prepare the first of two landers for a planned recovery. Then they completed intense surveys of the region encompassing acoustic surveillance for bubbling leaks from the well system, sediment collections, and scooping samples of floating oil from the ocean surface under guidance from volunteer airplane pilot flying overhead from the On Wings of Care organization.

Next it was on to the prolific natural seeps in the GC600 lease block, 140 miles to the west. Here, a second lander awaited preparation for recovery. This site hosts what MacDonald’s lab has identified as one of the most active natural seeps in the Gulf of Mexico. Falkor’s acoustic array detected even more seep sources than had been expected, delineating new seep sources dubbed Megaplume and Birthday Candles. But more bad weather put ROV operations on hold again.

Lander recovery preparations were quickly completed when the weather abated and an autonomous video camera was set down to watch the Megaplume, but now the team had a new problem. Prolonged bad weather had forced the cancellation of R/V Pelican, a much smaller vessel than R/V Falkor. According to the cruise planning, landers were supposed to be taken aboard Pelican. Could the team find a way to recover the lander with Falkor working on its own?

Thankfully, the answer was yes, although not without intensive planning and overcoming of some operational issues. Initial attempts to release the lander acoustically were unsuccessful, so the ROV was sent down to try to mechanically release the lander weights. After some vigorous pulls on the release line, the lander took off trailing mud from its feet like rocket trails, returning a payload of precious and one-of-a-kind samples to the surface. Once the lander was spotted bobbing in the waves, it was up to the Falkor deck crew to chase it down with the small work boat, hoist it with the starboard crane, and secure it for safe transport back to shore. Meanwhile, lander group leader Beth Orcutt quickly improvised ways to safeguard the lander’s samples and instruments.

Just three days remained in this eventful leg. After another day of successful dives at the GC600 seeps, on November 17th, Iliana Baums’ group made another live coral collection, this time from more than 1,000 meters depth and targeting a different species of coral. The autonomous video camera was left at the coral site to await recovery by the next leg.

The final operations day was carried out back near the Macondo wellhead. Having succeeded with recovery of the first lander, the team was determined to try for the second. This time, practice paid off and the lander was quickly launched toward the surface. A final multiple core collection marked the end of the lander leg on the evening of November 18th as R/V Falkor headed for Pascagoula.

Leg 2 Objectives

Now the R/V Falkor will head back out to sea with Chief Scientist Chuck Fisher from Penn State to focus on deep-sea coral communities. The primary objectives for the second leg include:

1. Collecting live deep-sea corals using the ROV for shipboard experiments and studies at institutional laboratories;
2. Returning with the ROV to long-term study sites and re-imaging corals to follow the outcome of impact (or lack of impact) on the corals from the Deepwater Horizon Oil Spill;
3. Recovering a time-lapse video camera system deployed on the previous cruise leg;
4. Obtaining water and sediment push core samples at study sites with the ROV;
5. Deploying the multicore to collect sediment samples;
6. Conducting multibeam mapping surveys in the evenings after ROV and multicore operations for bathymetric and bubble plume maps.

The cruise logs will continue to post stories and pictures describing the activities of the science team while they are onboard R/V Falkor for the next ten days.

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