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Click below to go to the Cruise Logs - (photo credit: Lophelia Coral - Open-File Report 2008-1148 & OCS Study MMS 2008-015)

DISCOVRE 2009



Cruise Log: 12/08/2009    



The Realities of Field Work: Troubleshooting Coral Experiments and Battling with Troublesome Weather!

April Zilg

Three coral mesocosms were attached to the BOBO lander. Coral was stained pink in order to assist with growth rate measurements - click to enlarge
Three coral mesocosms were attached to the BOBO lander. Coral was stained pink in order to assist with growth rate measurements - click to enlarge
As a graduate student on my first DISCOVRE cruise, I am merely along for the ride and giving a helping hand in whatever I can, and am here to learn what I can from others.

The first work day on the ship lasted almost a full 24 hours…and it was all spent preparing. After breakfast we made sure everything was packed and tied down, had a meeting, and got underway. I was able to take a short nap at this time. It was surprisingly easy to sleep because the cabins are so dark and the water movement is relaxing. Although, all the talk on the ship about 14 foot seas in the coming days was still in my mind, and made sleep a little difficult. I woke up early so that I could watch the landers go in the water. There were two landers: "BOBO" which was very tall to allow the device attached beneath to record current speeds at the seafloor, and "Albex" a short stumpy little thing that measured pH, DO, salinity, temperature; had sediment traps, and a camera that took periodic snapshots.

The most exciting part about the landers for me were the mesocosms, or what we just called "coral buckets." They were small cylinders designed to protect the Lophelia corals while they traveled to the seafloor, but allowing the corals to be exposed once they reached the seafloor. The mechanism worked like this: a base of syntactic foam inside would hold the Lophelia coral and then float up out of the bucket part so that the corals were exposed when down below. The bottom line is that the pink-dyed corals were being put down on the landers so that Dr. Brooke can look at the growth rates. I had an increased interest in the Lophelia because I had been looking after the tank they were held in since they were shipped to the Center for Marine Science last week.

April is filing down the magnesium on the quick releases so that they dissolve faster in seawater and release sooner - click to enlarge
April is filing down the magnesium on the quick releases so that they dissolve faster in seawater and release sooner - click to enlarge
On Tuesday, we put the corals in their buckets on the landers and watched as the first lander went in. When it came time for the second lander, Sandra realized that the coral buckets weren't working correctly - the syntactic foam was not floating with the added weight of the corals. This was a huge problem! Steve, Sandra, and Mike put their heads together and decided to make the lids removable and attach them for the ride down with dissolvable magnesium eyelets. If these metal eyelets dissolved correctly, they would release the lids, exposing the pink Lophelia growth experiments to the deep sea conditions that we needed to test. Being the new kid on the block, it was my sole duty to sand down these eyelets so that they would dissolve more quickly once "Albex" reached the bottom. I accomplished this mission, and proceeded to help them modify the chambers. Finally, the second lander went into the sea, carrying the coral buckets down to the ocean floor.

Then I began my 6pm to 6am night watch duty. The entire night consisted of a taking conductivity temperature depth (CTD) readings along a transect. I took 7 readings total, one every 1000m. I spent my time watching the depth of the CTD along with the data readouts so that I could coordinate with the bridge, telling them when to lower it or bring it up. As the night progressed, the weather got worse. Finally, it was time for me to turn in. Sleep was broken into segments of rest and holding myself into the top bunk while the ocean tried to throw me out of it.

I woke Wednesday to us going inshore due to the waves. We spent the night on the ship, anchored at the dock. On the way back out I got very seasick and slept for 17 hours.

Friday night I woke up for my shift after 17 hours of sleeping. We spent the 12 hour shift deploying an otter trawl. We used it to take samples of fish species in the area for isotope and genetic analysis. For isotope samples we took muscle, gill, caudal fin, and liver tissues from the fish. The isotopes are to study food webs, and they provide data that allows us to analyze how the fishes spend their time residing in different types of habitats. We can also analyze animal movement patterns. By measuring multiple tissues, we collect a temporal record of animal diet from short to long time scales.

For genetic samples, we took tissues from the gill and muscle. The genetic samples are to analyze the genetics of the species to determine similarity/difference of the specimens we are collecting to "known" species - that is, species that have already been well-documented by science. We are interested in understanding the population structure of the reefs; whether populations of a certain species are distinct in different regions or represent one population spread out over a large spatial scale. This was all very hard work, but there were so many interesting species to be seen. We had to preserve all the specimens in either formalin or ethanol.

Saturday, the weather got to the point that the captain told us not to deploy the otter trawl. He brought the boat further inshore to shelter us from the waves. We spent Sunday inshore, but this gave me time to talk to Dr. Ross and Dr. Brooke about my graduate project. It was nice to get some direction and be able to relate some of the activities on board to what I would be doing in the future. Half of Sunday night we spent traveling back to the site, the other half we deployed the otter trawl. We deployed three times and only got a catch on the first shot.

Monday night, and only one night after this to go! We have just deployed the benthic trawler, a design of trawler from a 1970's scientific article; also know by us as the "terminator." This piece of equipment is a very large metal structure designed to skim along the bottom and pick up all in its path (very much like a big metal otter trawl). This contraption brought up a few fish, an odd electronic piece that seems like someone else's lost experiment, and a slew of polychaete worm tubes. The remainder of the night was more otter trawls, isotope and genetic samples, and cold roast beef sandwiches.



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