August 5, 2007
We weighed anchor about 7:00 am and set sail for our first water collecting sites. The boat stops every fourth site for a CTD casting. The CTD takes measurements of conductivity, depth, and temperature. It is also used to collect water samples at specific depths. But in the meantime, we take samples while the boat is moving. Grant taught Christopher (a grad. student) and me how to take the samples. We take three test tubes and prime with DI water and then with seawater. The seawater is taken from under the boat and comes out in a sink in the "wet room". Two test tubes are filled with filtered sea water, labeled and put directly into the fridge. These will be tested for nutrients back at the lab. The third test tube is also filled with filtered seawater and then two drops of chloroform is added. This will be used to determine the amounts of chlorophyll in the water. Then, two, two hundred mL of sea water is completely filtered through a vacuum pump system. The filters are removed and preserved in vials in a liquid nitrogen Dewer flask. Seawater is also added to a brown bottle that has chemicals (I believe it is iodine) in it - like a stain. This will be used to determine how bad a red tide will be.
Lunch was Thai beef. After lunch, divers went in the small motor boat with the GPS to locate a moored ADCP (acoustic doppler current profiler) that needed to be replaced. The device was found and brought on deck. It was covered in barnacles, sponges, crabs and other sea creatures. I helped to scrape the ADCP clean. We put a new ADCP in its place. The old one will be fixed up and used again. This device can measure how fast a current is moving across the entire water column. It measures water currents with sound, using a principle of sound waves called the Doppler effect. As sound waves travel through the water, they ricochet off particles suspended in the water and reflect back to the instrument. An ocean current data collector was placed in the water three different times. There were about 20 minutes of travel between testing sites. We were busy most of the time. During blank times, I read, talked to crew and scientists, and learned a few things. I know how to tie a rope around a clasp using a special tool. I was able to identify several organisms that we accidentally collected. I learned to read the computers to tell what I was looking at - depth, salinity, temperature, etc.
Dinner of pork loin. The sea is still calm, but the skies are a bit cloudy so I couldn't identify the constellations. We are ahead of our schedule so we may stay in port for one day...but who knows how the rest of the week will go. Lots of nice people on the boat - I hope to remember their names after I interview them!!