Luckily, there was a break in the high winds and sea ice, so Kim and I were able to accomplish several things this past week! We were able to go out sampling a few times, allowing me to learn more about our equipment and earn some boating experience.
So far we have seen several krill aggregations on the echo sounder, and yesterday we were lucky enough to see the krill themselves swimming around under the brash ice! At the moment there are only juvenile Antarctic krill (Euphausia superba) in the area, but later on in the season we expect to see more of the large adults. Antarctic krill can live for 6-8 years and can grow up to 60 millimeters in length.
A group of scientists from the University of San Francisco studying phytoplankton, led by Dr. Deneb Karentz, actually caught some krill in one of their net tows and much to our appreciation, brought them back for us! We measured the krill lengths, which we then use with the acoustic data to calculate krill biomass and abundance. All of the krill measured were smaller than 20 millimeters, which means they are most likely a year old. We have also seen a lot of foraging activity from the penguins and seabirds in the area, it looks like it might be a good year for krill!
After 9 days of traveling, I finally arrived at Palmer Station, Antarctica! I flew from Dulles International Airport down to Santiago, Chile and then landed in Punta Arenas, Chile to await my voyage by sea, aboard the Laurence M. Gould research vessel. I am working on a zooplankton acoustics project with a Post-Doctoral student Kim Bernard from the Virginia Institute of Marine Science. I will be living at Palmer Station until I return home at the end of December.
Before heading to the ship, I made sure to rub the toes of a statue in the main square of Punta Arenas. It is a local tradition to ensure safe passage across the Drake (waters separating South America and Antarctica). One observation I had about the city, is that it is ruled by dogs. They are everywhere, roaming around in packs, sitting at street corners and outside shops, and occasionally escorting you as you walk through their turf. The city even has trashcans marked only for food scraps, specifically at dog height.
While going across the Drake Passage, all of us helped deploy Expendable Bathy-Thermograph (XBT) and Expendable Conductivity Temperature Depth (XCTD) probes. XBT probes measure water temperature, while XCTD probes tell us water temperature and conductivity. A group of scientists is studying the ocean currents in the passage, and hope to release these probes for the next 50 years to obtain data. Some of the ship crew joke that by the end of the project, there will be stepping-stones across the Drake where the probes were dropped. The procedure is to shoot the probe out and let it transmit data for a few minutes, which is then repeated every 30-45 minutes.
Additionally we obtained seawater samples, to measure oxygen content and nutrients in the water. Here I am in the process – I really was excited to be helping, I must have that face on because I had left my hat inside (it was around -13 degrees Celsius with the wind chill).
Our fifth day at sea, we stopped at the King George Island to unload researchers and supplies to the Copacabana (Copa for short) field camp there. I was a ‘sherpa’, which meant I helped load supplies off the zodiacs and onto land. It was a lot of work, but nice to be so active after a few days at sea. We were able to see penguin colonies hanging out around the field camp, and a few even wandered over to see what we were doing on the beach.
So far at the station I’ve gone hiking up the glacier in our backyard, and will soon learn how to drive and operate Zodiac boats. I’m excited to get the season started!
VIMS post-doctoral research associate Kim Bernard will be returning to the U.S. Palmer Research Station on the Antarctica Peninsula for another field season beginning in mid-October. Traveling with her is W&M undergraduate Domi Paxton.
Their research, part of the ongoing Palmer Long-Term Ecological Research Project (PAL-LTER), focuses on the distribution patterns of Antarctic krill in nearshore waters, and on how these patterns change across time and space. They relate their findings to physical drivers, such as tidal phases, and to the foraging ranges of Adelie penguins. Krill are an important part of the Antarctic marine food web, providing the main source of energy for marine mammals, penguins, seabirds, and fish.
During the upcoming field season, which will stretch into February 2012, Bernard and her colleagues will use acoustics to detect krill aggregations and to estimate their abundances and biomass. They will also try to collect krill samples from net tows to measure length frequencies of the krill in the area. Most of the work will be done from a Zodiac fitted with an echo-sounder—the researchers will go out every day during a diurnal tide and then for up to 5 days into the following semi-diurnal tide to monitor how the tides affect krill distribution patterns. (The Antarctic Peninsula is one of a few places in the world that experiences both tidal types.) She expects to see 4 or 5 series of diurnal to semi-diurnal tides and will attempt to sample all of these.
Bernard will also be going out on the research vessel Laurence M. Gould to conduct an acoustic survey of the head of the Palmer Deep Canyon (which is too far offshore to reach using a Zodiac from Palmer Station).
Bernard says that her work will “contribute to the PAL-LTER through improving our understanding of the physical drivers of krill distribution patterns, and will provide important information in terms of key penguin foraging areas.”
After our little break at Avian Island we immediately began our second of three Process Studies. This process study is focused in the waters surrounding Avian Island to look at the environment where the penguins are feeding and the quality/types of the food the penguins are eating.
The intensive study began with Dr. Grace Saba, one of our phytoplankton post-doctoral researchers (and her team of helpers), setting up a complicated CO2 addition experiment to see how different levels of carbon dioxide affect the phytoplankton, bacterial, and viral communities. She had previously done an experiment at the beginning of the cruise to test the effects of increased CO2 levels on krill. These experiments involve very intensive set-up and sampling every few days and their entire group has been working very hard and they have already been seeing some interesting preliminary results!
We then moved on for some intense sampling, hitting stations that were only about an hour apart and doing the full suite of sample collection at each station, including all of our net tows. Our sample processing rapidly got backed up and we had to slightly alter the way we were processing our tows to make sure we finished in time. About halfway through the Process Study we received satellite tracks from three of the penguins the bird researchers had tagged when we dropped them off on Avian Island. Based on those tracks, we shifted our sampling to include the locations where the penguins were feeding just a few days prior and continued our intense sampling.
Needless to say, we all worked around the clock to finish processing our samples, and even had time to squeeze in some experiments. It was an exhausting Process Study but in the end will provide very valuable information in the area where thousands of breeding penguins feed. And again, another perfectly timed break was scheduled for us to visit Rothera Station, the British base on the Peninsula that hosts the British Antarctic Survey and some of our British collaborators.
Shortly after leaving Palmer Station we reached our first oceanographic sampling station and began our science! We are part of the Palmer Long-Term Ecological Research project (PAL-LTER) which has been sampling the marine ecosystem along the Western Antarctic Peninsula for about 20 years now.
There are several scientists involved in this project—a physical oceanographer who studies the water masses and currents, a bacterial guy who studies, yes … bacteria, a phytoplankton guy who also operates gliders, Debbie the zooplankton person, and people that study the seabirds. Gliders are autonomous underwater vehicles—a fancy phrase for a torpedo-shaped vehicle that glides in the water, collecting information on water quality. It’s the latest, greatest piece of technology being used by oceanographers.
Each scientist has their own team of technicians and graduate students that help out with the research and do some side projects on their own. At each regular sampling station (which takes about 7 hours to complete), each group has their own task to perform to collect samples, which becomes like routine clockwork after the first few stations (unless something goes wrong or breaks … knock on wood). These stations are laid out like a grid along the Peninsula from north to south, extending about 200 kilometers (120 miles) offshore. We sample the same stations every year, providing a nice long-term dataset.
At each regular station our zooplankton group collects critters using three different nets—a very large square-frame net (2m x 2m) to collect larger zooplankton like krill and salps (gelatinous animals, kind of like jellyfish that don’t sting), a smaller square-frame net (1m x 1m) to collect smaller animals (like copepods), and a small ring net (0.5 m) to collect microzooplankton (very tiny single-celled zooplankton). The nets are attached to a cable and towed behind the ship to a certain depth. There is a bucket (called a cod end) at the end of the net that collects all of the zooplankton. When the net is brought on board we dump everything that we catch into a big tub. All of the animals we catch in the two larger nets are sorted and counted live on the ship. Most of the critters are large enough that we can easily identify them, although sometimes microscopes are needed for the slightly smaller zooplankton that we catch. The contents of the small net are preserved immediately and processed in the lab back home.
At three stations called “process study stations” spaced out along the grid close to penguin feeding areas, we stay for about three days and do more in-depth sampling. Our zooplankton group does day and night MOCNESS tows at these stations. MOCNESS stands for Multiple Opening and Closing Net Environmental Sensing System and is a large, complicated frame that can hold ten nets at a time. The nets can be triggered to open and close at different depths so that we can sample the zooplankton community at specific depths. We do day and night tows because some zooplankton are known to vertically migrate. This means that they are found in the surface waters at night in the cover of darkness to feed, and then they migrate deeper during the day to avoid being eaten by some predators that rely on their eyesight to hunt and feed in the surface waters. Using the MOCNESS, we can sample specific depths during the day and night to see if any of the zooplankton species show this behavior.
In addition to the MOCNESS and our regular net tows, I do experiments for my thesis research at these process studies. I do two experiments, called dilution experiments, that measure microzooplankton grazing on phytoplankton and bacteria. They are very time-consuming to set-up and take down, but I always have someone to help me to make things go quicker and also to make it more fun. Dilution experiments are kind of tricky to do and don’t always work exactly how you would like them to, so I’m keeping my fingers crossed that this year they will go well. I’ll keep you posted.
Our group also does fecal-pellet production experiments to measure how much the krill and salps are pooping. Not only do we measure how much they poop, but we also do sinking rate experiments to measure how fast the krill and salp poop pellets sink. That literally involves putting a piece of poop in a clear tube of seawater and timing how long it takes to fall a certain distance. We have poop races sometimes. This might sound a little bit ridiculous, but it’s actually very important. The ocean removes a lot of the carbon dioxide that’s in the atmosphere, which phytoplankton use when they photosynthesize (if you remember your Intro to Bio class, plants use CO2 for photosynthesis, removing it from the atmosphere). Zooplankton eat the phytoplankton, packaging them into fecal pellets that they poop out. Some of the fecal pellets break down in the surface waters and the carbon in them in released, but some fecal pellets make it to the ocean floor and the carbon in them is buried by sediment. This cycling of carbon by zooplankton, part of the “biological pump,” removes carbon from the atmosphere and puts it in the deep ocean. So, poop really is important!! Especially today with the ever-rising CO2 concentrations in the atmosphere. And we think it’s fun playing with poop sometimes too!