As I write this I am sitting on the fourth floor, otherwise known as the bridge, of the Nathaniel B. Palmer (NBP). The winds are gusting up to 40 knots and snow is accumulating on the ship decks. I can just barely make out Rothera Station* tucked away in the mountains behind a blanket of clouds and ice. We are just south of Adelaide Island and are about to leave Marguerite Bay, Antarctica, where we spent the last week and a half collecting data and running our onboard experiments.
When in the southern reaches of the Western Antarctic Peninsula, the ice is a bit thicker, which can make the echosounder a bit noisy. As the sonar beams hit the ice, they create spikes on the screen, making it trickier to see the krill aggregations. However, if you know what you’re looking for, you can still see the krill hiding between the noise.
Our first task was to capture enough juvenile krill to run our growth and respiration experiments. These experiments are meant to help us better understand the physiology and behavior of juveniles during the winter. The first night of searching for krill was quiet, and we only got about half of the number of krill we needed. Undeterred, we started our respiration experiment and got ready to collect krill the next night.
In the middle of eating my “breakfast” at 3 pm, we saw an aggregation on the echosounder. Not huge by any means, but big enough for us! I got the team geared up and ready to go and we sent the net down to 300 meters where the aggregation was. The tow was deeper than what is typical for a krill tow, because we did it during the day when there was still light out. ** As we pulled the net out of the water, a rush of krill came pouring out of the cod-end!***
We were ecstatic! Along with the krill, we caught some cool pelagic critters including polychaetes, copepods and juvenile shrimp! With our experiments well underway, we spent the following nights sampling the water column looking at krill prey diversity and abundance. We collected additional krill to get an idea of their abundance and distribution in the southern region of the Western Antarctic Peninsula.
We worked long nights and ended up collecting some really cool data! We’re finishing up our time here in Marguerite Bay and are getting ready to head north to begin sampling there. In addition to the awesome science happening onboard the NBP, we’ve seen some pretty cool sights, including the hundreds of fur seals that were hauled out on ice floes yesterday.
Now that we have a couple of days to rest and recoup before starting our next round of data collection, Andrea, Giulia and I have to start preparing a skit to please Neptune (a.k.a. Poseidon). In order to join the renowned Order of the Red Noses (i.e. those that have crossed the Antarctic Circle), we have to please our ocean God and be officially instated as a member. It looks like it’s time to go rehearse.
*Rothera Station is the British Antarctic Survey’s research base on southeastern Adelaide Island, Antarctica.
**Krill, like most other zooplankton, perform a diel vertical migration (DVM), where they spend their time in deeper waters during the day to avoid predation and in shallower waters at night to feed. In the winter, DVM isn’t as pronounced because it’s dark most of the time and krill tend to hang out in deeper waters than they do during the summer.
***A cod-end is attached to the end of the net and it is where zooplankton are collected during net tows.