Entry 13
March 02/03 2025
Another day another CTD. -80 degrees, lunch time naps and a fishing trip.
Today was definitely the craziest day we've had so far - and on a Sunday too. Alarms went off at 02:45am, which is feeling pretty normal by now, and we headed down to the main lab to watch the CTD profile as it went down. Whilst my filters were filling (15L per line takes me about 1.5hours), we filtered samples for SEM, which will allow us to visualise, count and identify our plankton to get an idea of their diversity and community changes over physical gradients. Having snap frozen my samples, stored them down in the -80, and acid-rinsed my carboys, I finished up my first shift around 10:00am. Then it was time to convince my body to sleep again (in fairness, it had been working for 7 hours), to store up a few hours in anticipation of the next night shift.
I resurfaced just before dinner (or is it breakfast? I've lost track) and checked in with the day shift crew as their evening CTD went down. Once it was back on deck it was time for the affectionately named ‘fishing trip’. This is the deployment of the Tow-Fish, the sampling device that will supply us with trace-metal clean surface seawater straight to our RN container, so we can do our 120-hour nutrient addition experiments. We took the Fish out of her box and re-applied the electrical tape we had so diligently removed (oops!), and before long it was time to get her up into the air and over the side. With the help of Tina, Paul P and Richie (NMF Techs and the real stars of the research cruise show), as well as crew members Burt and Andy, we managed to get the Fish in the water whilst the captain ramped the ship up to 5 knots to flush through the system.
This was the most exciting moment of the cruise so far for me, and I'm so pleased to say the whole thing went off without a hitch in the end. We have an ongoing joke that this is our experiment when it’s going well, and my experiment when it’s not (or when it's keeping us up at unsociable hours), but all joking aside, this is really my baby and I am super excited to have it underway. We'll hopefully have three 5-day experiments over the next few weeks, which should give us temporal and spatial resolution of nutrient limitation and co-limitation across the South Atlantic
Once the Fish had flushed through for a few hours, it was time to get down to the business of filling bottles, taking T0 samples and spiking with nutrients, which took us 'til around 0200. Dropping the bottles into the on-deck incubator was an extremely satisfying moment. Add another few hours of filtering, fixing and freezing and it was a 0400 bedtime for us, making this a 25-hour shift in total (with a little lunchtime nap). I'll see you tomorrow, not too early though.
