A Day in the Life (and some other things)

November 20, 2019 | Dr. Wade Jeffrey, Director of CEDB | wjeffrey@uwf.edu

A Day in the Life and some other things

             So what’s a day like onboard the ship? For us it’s always a working day. We collect our first sample with a CTD profile at 5 am, so that means I am up at 4:30. The seawater is usually onboard by 5:45 am. We scramble to collect water from the correct bottles for the depths we want, and then it’s off to process. There are samples/ data to be collected from each water sample which requires a lot of filtering water (we collect material on different filters for different assays that will be done once we get home).  There are also samples for nutrients (how much nitrogen and phosphate are in the water), microscopy, and flow cytometry (an automated instrument that counts particles in the water, including bacteria and phytoplankton). In my case, I am responsible for the measures of growth and production. It usually takes about 2 hours to get them all started (there are five different assays on each water sample). Microbes in the ocean grow at rates too slow to observe, so we need more indirect ways to measure growth.  For bacteria, the most common way to do it is by adding a radioactively labeled “food” that they can eat and we measure the uptake of that radioactivity.  The “food” of choice is called leucine, which is an amino acid, or one of the building blocks of proteins, and it is labeled with radioactive hydrogen, called tritium, and written as 3H.  How much 3H-leucine is incorporated is proportional to how much protein is synthesized which is proportional to growth.  You’ll have to take my word for it, but lots of people have tested this relationship and it holds up and is valid.  Because much of our interest is in how light is affecting growth, we conduct these growth incubations outside on the deck in UV transparent tanks with seawater flowing through them (photo).  There is another experiment conducted inside the lab where we use different light levels produced by a lamp. For phytoplankton growth we are measuring photosynthesis – remember all plants do this.  Here we add carbon dioxide which has radioactive carbon, 14C, on it – again, after time, we measure how much carbon is fixed into organic carbon which is what photosynthesis does.  This is also done in both outdoor incubations as well as inside using lamps. So normally I finish all this in time to catch breakfast (between 7:30 – 8:30).  Then I have a short window when I check email (remember, I still have a day job at the university) and try to process the data from the day before’s experiments. This is usually how I spend time between tasks all day long.  My first incubations end about 10:00 am, lunch at 11:30-12.  At 1 pm we conduct a light meter profile off the back deck.  This tells us how much light there is at depth compared to how much is coming down from the sun.  We usually measure it to about 60 meters deep.  This is critical information since we are studying light-dependent processes.  Right after that, the second set of incubations ends.  We have to stop those reactions as well as measure the light produced by the lamp we are using in the lab.  Dinner 5:30 – 6:30. Right after dinner we stop the third set of incubations.  Then I spend about 2 – 3 hours processing the samples (a three-step centrifugation method) so that we can count the 3H-leucine samples to get the data.  One last check of email and then I start heading to bed.  At 7 am the next morning we finally stop the last incubations.  These days are complicated on the days we do one of the experiments for Leila’s thesis project – that adds filling 36 small bags at 5:45 am with water which incubates outside in the on-deck incubators. We collect the first time point at 6:45 pm (which then includes a 2-hour incubation for growth that I add in there).  The second time point is right before sunrise – which in our case means before 3:00 am.  Again a 2-hour incubation means I am up until about 5:30. Sleep happens in between and around sampling.

            But it’s not all work – we are regularly amazed at who comes to visit the boat.  Here are a couple of photos of chinstrap penguins that swarmed around the ship a few nights ago.  Then last night we had about 25 humpback whales feeding around the ship for hours. So yes, if possible we stop and spend time on the deck with cameras in hand.