July 14, 2006 Options

[Betty_Carvellas]

July 14, 2006

We started the first of these four mud stations at 1:30 this morning, and we finished them by 2 this afternoon. I have a bit of a break right now before we start a line of CTD stations across the Bering Strait that's scheduled to last from 9 PM through 5 AM. Unfortunately, Jackie gets almost no rest since she is running her respiration experiments. Our 'team" this year consists of Dr. Jackie Grebmeier, Dr. Lee Cooper, Rebecca Pirtle-Levy, and me. I'll tell you lots more about Jackie and her work once we finish our last stations and I can get someone to take pictures for me. Rebecca is my roommate on this cruise, and I'm lucky to be working with her again. This is her 6th year working with Jackie, first as an undergraduate, then a Masters Degree student/research assistant, and now as a technician. I remember collecting extra samples for Rebecca when she was doing the research for her Masters degree. She was looking at the chlorophyll levels in the sediments and investigating the possibility of a food bank when there is no primary production occurring; an example would be when there is total ice cover and no light reaches the phytoplankton. It's great to work with Rebecca because she knows Jackie's sampling procedures inside and out. In the picture, Rebecca is collecting water from the CTD bottles.


Rebecca Pirtle-Levy is collecting water from the CTD bottles for chlorophyll-a, oxygen-18, and nutrient analysis.

It's probably time that I told you what happens at a "mud station." A "mud" station starts with the CTD cast. Either Rebecca or Lee will take water from the CTD while the rest of us get set up for the mud grabs and cores. They take water for chlorophyll-a analysis, oxygen-18, and nutrients. While the oxygen-18 and the nutrients are preserved for later analysis, Rebecca and Lee will process the chlorophyll-a on the ship. Chlorophyll-a is found in the cells of plants, and is an important indicator of "productivity," or the availability of food in the water. After filtering the water, they place the filters in glass vials in the freezer, for one hour, to break the plant cells and release the pigments. They then extract the chlorophyll-a by placing the filters in acetone in the refrigerator. Twenty-four hours later, they will take chlorophyll-a readings (measurements) from each of the twelve samples with a fluorometer. They'll also take chlorophyll-a readings, after twelve hours, from the mud samples from both the van Veen grab and the Haps core (equipment used to collect mud). The tough part about all this is that, once we get going, the samples start to back up, and someone needs to get up at all hours, not only for the CTD casts and the mud work, but for taking chlorophyll readings as well.

I first worked with Dr. Lee Cooper of the University of Tennessee, Knoxville, in 2002 on board the U.S. Coast Guard Cutter Healy, and he was on board this cruise last year. Lee's work involves collecting water to analyze for oxygen 18, an isotope (different form of the same element, this one with 2 extra neutrons) of oxygen. By analyzing the ratio between oxygen 18 and oxygen 16 (the most common isotope), Lee can track the source of the fresh water component of the water he is sampling. As the Japanese current, Kuriosho, comes across the Pacific, it splits upon reaching the coast of North America. It heads south to California and north to become the Alaskan current that runs along the southern coast of Alaska and the Aleutian Islands. As it reaches the passes through the Aleutians, the current turns north into the Bering Sea. You might remember from a previous journal, that we traveled through Unimak Pass into the Bering Sea. The Unimak pass is the first pass where Pacific water freely flows from the Pacific into the Bering Sea. Lee should be able to tell, in general terms, if the components of the fresh water are from Japan or from the rivers, glaciers, and melting snow of Alaska or both. The farther north, the colder the temperature, and the higher the altitude at which the precipitation fell, the more depleted the oxygen 18. His data can help determine the amount of fresh water from Alaska, such as from melting glaciers, and therefore provide indications of global warming.


We were doing a mud station when Lee noticed this rock we had found in mud from one of the SLIP stations. Lee was pretty certain that it was granite from Little Diomede Island which had probably moved south, on the ice.

Photo by: Koji Shimada

As I went into the mess today to check on snack options, I saw an unusual sight. Jackie Callen, ship's nurse, was working with Harold preparing sushi for dinner. When I expressed surprise at seeing her there, Harold explained that we had all been staying very healthy and therefore not keeping Jackie very busy, so she volunteered to help out with dinner preparations. I had the sushi for dinner later that night; Jackie did a great job.


Jackie Callen is actually the nurse on board the Laurier. She took a break from her own duties to help make sushi for dinner.