It’s hard to believe, but we’re nearing the end of our allotted science days (it’s also hard to believe that we’ll spend more than two weeks just to get back to port after science ends, but that’s a whole different story). However, our work doesn’t stop when the official science period ends — we will still be working on some of our experiments as we head back north.
The majority of our time on this expedition has been spent observing the ocean in its natural state — either by collecting seawater and analyzing it for things like nutrients, inorganic carbon, and chlorophyll, or by pulling instruments through the water that collect data for us. But sometimes we’re also interested in conducting our own experiments, to see what would happen if the ocean were just a little bit different (these are the experiments I mentioned in my last post, where we used Big Jon to collect the water as far away from the ship as possible).
We’ve been working on these experiments throughout the cruise, and we’ll continue to do so for a few more days after we’ve stopped collecting samples (each experiment takes about 5 days to run). For each experiment, we take the “raw” seawater collected from a particular area of interest and dose it with a different combination of nutrients and trace metals. These containers of water (including the all-important control group — seawater by itself) are kept in big tanks out on the back deck. We have a heating/cooling system in the tanks to keep the little critters happy at the same temperature the original water was at.
Much like humans, phytoplankton like different types of snacks — diatoms are usually found in waters rich with tasty silica, for example. The aim of our experiments is to determine which types of phytoplankton thrive under those new conditions. Some of the containers get spiked with a single nutrient, like nitrate, while others get a combination, like silicate plus iron. We’re also testing out dosing some of the containers with a certain type of water known as Subantarctic Mode Water (SAMW — hey, that’s the name of our cruise!).
Subantarctic Mode Water is the nutrient-rich water that forms in the northern parts of the Southern Ocean and then spreads northward at depth. It delivers nutrients to nearly three-quarters of the rest of the ocean, so we’re really interested in figuring out just what makes this “special sauce” so special.
For each experiment, we take the same measurements as we do on all of our other water samples. Some of the information we’ve already learned from our first sets of experiments is helping us design the last sets of experiments by letting us know what to focus on. We also collect DNA samples so that once we’re back on land, we can identify exactly what types of phytoplankton grew under which conditions.
The seas have been getting rough over the past day or so. We’ve also apparently become a bit complacent in the nice weather over the past 40 days, because cups, chairs, and sample bottles were flying across the lab today (don’t worry – everyone escaped unscathed). A fierce cribbage tournament is underway (named the Balch Antarctic fLoating Cribbage Hurrah because oceanographers always love a forced acronym). Captain Wes is definitely establishing himself as an early favorite but there are still plenty of games to be played! Updates to come…
Giuliana Viglione is a journalist and science communicator who has joined Senior Research Scientist Barney Balch’s research cruise to study the impact of coccolithophores in the Southern Ocean. On board the ship, she’ll be helping the team carry out experiments, document the research cruise, and conduct educational outreach with students across the country. She can be reached at email@example.com.