Sunday, May 19, 2013

Search and recovery for moorings deployed in May 2012

RV Pelican docked at the Louisiana University Marine Consortium (LUMCON)
(Wednesday, May 15) We left just before midnight, out of LUMCON (Louisiana University Marine Consortium) in Cocodrie, on the R/V Pelican. It was quite a sight to see the horizon lit up by all the oilrigs and shrimping vessels, as the boat navigated its way out of the marshes of Louisiana. Among those on board were Dr. Cathrine Hancock and graduate students Elizabeth Simons, Kelsey Rogers and Lauren Gillies, all from Florida State University (FSU). Once we were safely in the Gulf, it was off to bed.

John Ahern and Cathrine Hancock
lowering the CTD Rossette into the water
(Thursday, May 16) The fun started at 9am with CTD (conductivity, temperature and depth) casts and water sampling going on through the day and night. A whole array of instruments located on the CTD Rossette gave us measurements of temperature, pressure, conductivity, dissolved oxygen, chlorophyll a, turbidity, and various optical properties of water. Water samples taken by Kelsey and Lauren, are to be analyzed back at FSU for methane concentration, oxygen concentration, nutrients, cell microscopy (identifying cells and performing a cell count using a microscope), microbes for DNA/RNA work, and POC (particulate organic carbon) for carbon isotope work. The last station was completed at 3 am on Friday, at which point everyone was ready for bed.

(Friday, May 17) Mooring operations commenced at 7 am under the leadership of Chief Scientist Jim Singer (SAIC). They worked hard all day under the hot sun, pulling up moorings that had been deployed a year ago. Each mooring has an array of instruments measuring temperature, conductivity, pressure and currents, at different depths in the water column. Everything went smoothly until we arrived at the last mooring of the day, M3. It had been dragged 3500 meters from its deployment position. This meant we had to do a little ‘search and recovery’ session, which put us behind schedule for the nightly CTD work. Once mooring M3 popped to the surface, we realized that the wire had been cut right above the bottom flotation, which meant most of the instruments were lost. With the amount of shrimping boats in this region, it probably got caught in someone’s net and the wire cut to save their net. Once mooring M3 was securely on board, we headed for our first CTD station. It was another long night of CTD work, and despite the late start, we managed to complete three of the six planned casts.

Paul Blankenship, Craig Boyd and John Evans recovering a mooring.
Kelsey Rogers, Lauren Gillies and Elizabeth Simons
taking a break in the galley
(Saturday May 18)  The second day of mooring operations started at 7 am. Already on the first TRBM (Trawl Resistant Bottom Mount) we encountered problems, as it did not surface upon release. This meant we had to drag the bottom with grapnel hooks to catch the wire. In the end it was successfully recovered. We encountered the same problem on the last TRBM, and again managed to recover it successfully by dragging the bottom. Once the deck was secure, there was time for one more CTD station before we headed back to LUMCON.

On our way back we were privy to dolphins, acoustic guitar music (courtesy Kendall Klay), a starlit night with satellite watching on the bow of the ship. It was a great trip, with an eclectic mix of interesting people. And last, but by no means least, the food that chef Alex Forsythe prepared for us each day was delightful. 

Dolphins riding the wave at the bow of the ship.
Post Author:
Cathrine Hancock

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