June 25, 2009

6-25-09

When a lot of people on the ship were enthusiastic at the beginning of the cruise about the beautiful sunny weather, I though I was just as excited. However, I was not on board for previous summer cruises where grey is the most common weather you see. At this point I am thankful for all the sun we have had because it has been almost a week of consistent overcast. Being from Oregon, I can handle some clouds, and as I long as I keep telling myself that it is summer it feels a little bit warmer than mid 40s. To go along with the mild cloudy weather, the water is extremely calm today. You could probably pull out the ski boat and go wake boarding. Getting the boat hundreds of miles back to land would be the difficult part.

When I have told people that I look at sediment from the bottom of the ocean, a few times I have gotten the question “Ooo, so you go down in those deep sea submersibles to get samples?” Unfortunately, and fortunately, no. No traveling to the sea floor and reaching into the sediment with remote control robot arms to collect samples. Unfortunately, because it would be very exciting to travel to the bottom of the ocean. Fortunately, because it would be challenging getting into a tiny tube for hours on end over and over coupled with the high cost associated with repeating such an expensive endeavor. It turns out you can do almost anything you would ever need from the deck of the ship with the right instruments.


The exciting thing about studying sediment is that it is a historical record for everything that has happened above it. Since sediment accumulates at a rate of centimeters every thousand years in the Bering Sea, you can look pretty far back into the past as you go down a sediment core. This was a shelf break area, where the water depth is increasing from the continental shelf to the deep basin. It was likely an area where not very much settling material will accumulate because it will simply fall down the slope to the basin. However, I am not sure if I will get a crack at another station like this, so I figure why not collect some sediment here if it is available. The shelf break can be an area of upwelling which can lead to some interesting biological activity.

It was a less than fruitful krill tow this morning, and we had arrived at an interesting station for sediment collection. I asked our shipboard sediment expert, Dave Shull (shown in the foreground with the white hard hat), if it was possible to get sediment from him at this site. “Possibly” he said. “If there is extra mud, you can certainly have it. That is, if the multi-corer works properly.” When ever I hear the word “mud” I can’t help but think about the mud wars my siblings, friends, and I would have at our family’s house growing up. It would usually end with someone getting mud in their eye and complaints as we cleaned the scattered mud off the dock. The concern of the multi-corer working properly didn’t register at first, but I got the idea after the first drop.

I got the chance to help deploy the multi-corer so I was not able to get many pictures. The multi-corer is lowered down to the sediment with a crane. The water depth at the station was about 200 m (656 feet). As the multi-corer came back onto the ship it was very clear that this was a difficult site to core sediment. In the picture of a core from a previous station, the far right core with not very much sediment was a very successful collection compared to this station. The sediment was very rocky and sandy making it difficult for the cores to close properly. Some of the cores had little or no sediment, others were leaking, but there were still some good usable cores. After a second drop, there was the same inconsistent success. Closely examining the sediment you could see rocks and pebbles sitting in the sand. With the coring difficulties, there were no extras for me this time. I’ll just have to sit tight until the next station. No problem, we still have over two weeks to go. There will certainly be plenty of mud to go around when it is all said and done. So long as I don’t get the urge to sling it at my fellow cruisers.

-Eli