My name is Stacy Kim, and I am the leader for Bravo-174, a research group down in Antarctica near McMurdo Station. We are on the sea ice right now. We are about five miles from the ice edge, along the channel that the icebreaker will ultimately cut to allow access to McMurdo Station for the shipping vessel and for the fuel vessel. We've chosen this area because we plan to use the shipping channel as an experimental manipulation.
Our study is to look at food webs and the impacts of predators on lower levels of the food webs. When the shipping channel comes in, it allows air-breathing animals - so that's penguins and minke whales and orcas - to come in and have access to prey fields they previously didn't have access to. So, that's the krill and the fishes and then the lowest level of the food web, the phytoplankton.
Right now we're getting a map of where the phytoplankton are, where the krill and the fishes are, and then in about a month or so, when the icebreaker comes through, we're hoping to get a map of what happens to those organisms' distributions once we have the orcas and the penguins and the minke whales impacting the system.
Here we have our remotely operated vehicle SCINI, which stands for Submersible Capable of under Ice Navigation and Imaging. It's a micro-scale ROV, so you can see it's pretty small. It's very maneuverable. It has five different thrusters on it: a main thruster for going forward and backward, and then two thrusters that allow it to go up and down, and two thrusters that allow it go back and forth, which also allows it to tilt and to turn. The pilots will drive it with a Playstation 2 joystick. It's like playing a big video game but you're actually controlling something in the real world.
Then we have this giant tow package behind it, which we call FATTI. It has a sonar system for imaging krill and fishes, and also a fluorometer for looking at chlorophyll pigments, which are an indication of the phytoplankton in the water column. So, with this package, we're looking at the bottom three levels of the food web - the phytoplankton at the very bottom, and then the krill and the fishes above that.
A little later on, when the penguins and the whales, the predators in the system, start coming in, we'll be tagging and tracking the predators as well. We're trying to determine if this whole system is driven from top-down pressures, so if it's the predators that are controlling what happens with the krill and the fish, or if it's bottom-up pressures - if it's the presence of the phytoplankton that's controlling the krill and the fishes.
That's interesting from an ecological standpoint because in a lot of systems - that we have studies that are terrestrial where humans have already had an impact - we see that the bottom-up drives the ecosystem. However, when we get into these marine systems, and systems that are less impacted, it looks more and more like top predators have a huger impact.
It's a pretty exciting moment when you get your oceanic equipment back from the ocean, 'cause once you put it in the water you're never sure if you're going to get it back. It's somewhat of a struggle to pull FATTI and SCINI out of the hole. It takes a few people coordinated to get everything out safely, but we had no problem with that.
The dive went really, really well. We got all of our transects done. We saw a very interesting, very intense layer at about 250 meters, and we also saw a spike in the fluorometry at about 500 feet or 150 meters. So, we're going to do one more Niskin cast to get some water samples from that depth to confirm what kind of phytoplankton were creating that chlorophyll maximum, and then we're going to pack up everything and move to our second site for the day - and do it all over again.