Erik's letter, answered by Dan Naber, Research Tech from Univ.of Alaska in Fairbanks

Hello Erik-
    I have one of your letters sent to us here on the Oscar Dyson. I am a research technician from the University of Alaska in Fairbanks. I work for a chemical oceanographer, Dr. Terry Whitledge. We have instruments on the moorings M2 and M5 that measure the amount of nitrate in the water. I sail into the Bering Sea every spring and fall on the Oscar Dyson or Miller Freeman to recover and deploy our instruments.
    As you may have learned in your class, nitrate is one of the nutrients that algae and other phytoplankton eatto grow. Other nutrients that algae and phytoplankton eat are phosphate, silicate and ammonium. By studying the cycles of nitrate levels along with other oceanographic data such as currents, water temperature and salinity you can begin to understand how the hydrological systems in the Bering Sea work and are possibly changing. These mooring sites have been studied for over 15 years now so trends can be seen..
    Nitrate levels decline during the summer when most of the biological activity happens and phytoplankton are eating the nitrates and other nutrients. Nitrate levels increase during the winter when nitrate from the deep ocean up wells onto the shallow continental shelf of the Bering Sea..
    Our instruments have been in the water for 6 months gathering data every hour. It is always exciting, for me, to recover the instruments and see how they have fared over the past 6 months and to see if we have good data. If there are problems with the data then you try and figure out why and make changes. If the data is goodyou continue with the procedures that produced that good data and see if you get good data again..
    I had to laugh when I saw Carol Dewitt pulled out one of the styrofoam heads from your class because I also brought a styrofoam head with me from home. It was a birthday gift from a friend of mine who knows that I go out to sea and will have a chance to send the head down over 2500 meters on a cruise I am doing right after this one on the Oscar Dyson. When the Dyson gets into Dutch Harbor I will stay in Dutch for 4 days and then get aboard the Tommy Thompson, a ship from the Univ. of Washington and spend 5 weeks aboard sailing in the Bering Sea taking many CTD water samples. I will send you an e-mail and let you know what happens to my styrofoam head!.
    You said that you think the styrofoam head will break up when sent down 1000 meters. I'm not so sure. If there was a large pocket of air inside the head I could see that happening but I am assuming the head is solid so the equal pressure that water exerts should compact the styrofoam, making the head smaller. This assumption may not be correct and could only be proven if the head was sliced open. There may be some places in the head where the styrofoam is less dense than other places in the head which may cause the shrinkage to be uneven causing the head to not keep its original shape..
    If you are interested in seeing some photos of how we recover and deploy the moorings you can visit some blog posts I have. The pictures are from an autumn mooring cruise on the Miller Freeman. Go here: http://bipolarexplorer.blogspot.com/2007/09/mooring-photos.html .
    I also have some photos from a mooring cruise on the Dyson but the photos are just of the inside of the ship and some photos from Dutch Harbor. Go here:
http://bipolarexplorer.blogspot.com/2008/05/spring-mooring-cruise-april-29-may-10.html.
    So far this cruise has been successful. We have recovered and deployed several moorings. In an hour or so we will recover the mooring at M2 that has my nitrate instruments on it so I'll be busy with that. The weather has been cold, near or below freezing with 10-20 mph winds and some snow. We may not get to the M4 mooring because of too much sea-ice. There have been some small bands of sea-ice down here at the M2 mooring. There will only be more of it further north. .
    Well, thanks for the letter. Hope I answered your question to your satisfaction. If you or your classmates have any other questions, feel free to e-mail me..
    All the best,     Dan Naber