3 December 2004
Pictures, old and new.
We are working today on revisiting sites that were established 30 years ago. In the late 1960s, Dr. Paul Dayton (then a graduate student, now a professor at Scripps Institution of Oceanography) started benthic research at McMurdo Station. Some of the experiments he initiated, to examine settlement and growth in this high polar latitude, are still on the seafloor. His results over a several year time frame indicated that growth of Antarctic organisms was very slow. We have been relocating these sites and imaging the organisms that have grown over several decades, and we are finding that while growth is indeed slow in the large, already established individuals, growth is very rapid in newly settled, young individuals. This surprising result has implications for our predictions about community recovery from human disturbances. While slow growth has been considered a hallmark of Antarctic species, our discovery suggests that initial stages of recovery may be much faster than expected, though the slow growth over long time frames indicates that complete recovery may take much longer than in temperate areas.
One of the things we are not able to do is to revisit every one of the sites that Dayton established. In the early days of scuba diving, when he first began his work here, safety limits were not yet established for scientific diving. His experimental sites were chosen based on the distribution of animals, and here, that is controlled by ice. In shallow (<12 m depth), where anchor ice forms annually, the animals are those that recruit quickly and can survive or escape being disturbed every year. Most of these are motile, and include seastars, urchins and nemertean worms. At intermediate depths (12-24 m) there is a rich, diverse community of polychaete worms and amphipod crustaceans. These are the infaunal animals that we focus on, because they cannot move far, live surrounded by sediments and often feed on the sediments as well; they are the species that will respond most rapidly to any changes in contamination levels. This "tube mat" community is in the depth range that is disturbed periodically - perhaps once a decade - by unusually cold years and ice formation to deeper depths. The third community is the deep one (>24 m depth) that is dominated by large, slow growing, sessile (attached to the bottom) species such as sponges. These are the animals that Dr. Dayton focused on, because they live for so long. Thus, his sites range in depth from 27 - 48 m, but our safe diving limit today is 40 m, so the deeper areas are not accessible to us on scuba. The extreme clarity of the water here lets us see them from the distance as we float above them, and it is very frustrating to see them so close, with no barrier but an invisible one of safety. We hope someday to return with an ROV, or remotely operated vehicle, that will allow us to reach those deep sites.
| Paul Dayton in 1954, using a scuba rig he built at home from plumbing parts, in warmer waters than the Antarctic.
|| An example of a large, slow growing sponge from an image taken during some of the early dives at McMurdo.
There are several unintended components of these long term growth experiments as well. Various items have fallen through the seaice; some were intentional disposal of large pieces of trash, and some were unintentional when the ice melted faster than expected. But for all of them, we know what year they were deposited on the seafloor, and so we can age any animals that are now living on them. At Hut Point, there is a gangplank that fell off a ship and several tens of meters of fuel line. In Winter Quarters Bay, there is a D8 tractor. Near the outfall, there is a Spryte (the old equivalent of the Pisten Bullys) and the body of an airplane. These historic items form part of our study on growth rates, and are a further example of making scientific use of parts of our everyday lives - like the way we are using the sewage treatment plant as a huge experiment on community recovery dynamics. Sometimes just being aware of changes can allow you to take advantage of opportunities that would otherwise be unattainable.
| One of the original photographs documenting underwater site locations in Antarctica. Today we use handheld GPS (global positioning system) units to relocate sites.
|| An ROV recently used on one of the Antarctic research ships, the RVIB Nathanial B. Palmer, with the deck crew that deployed and drove it. We hope to get a tool like this here in McMurdo to enable us to reach deeper sites.
And on taking advantage of opportunities, I have to mention our recent lack of opportunities to eat. With our season drawing to a close, we are trying hard to get too many things done each day, and our hours are driven by the research and not by the galley hours. So we miss meal after meal. Okay, so some of us have trouble making it to breakfast on account of it interfering with potential sleep time. And then lunch is inconveniently in the middle of the day, when we are out diving. Dinner comes too early, often before we get back from the field. BUT - we thought we were going to be saved from missing all the meals in one day by the Burger Bar, which is open 2 nights a week and is later than regular meals. We were all salivating as we drove up the final hill and quickly unloaded our precious samples, leaving all the non-critical things like washing and cleaning for after feeding. We had 45 minutes - plenty of time - but were thrown into the depths of despair by the Bar having closed early on account of overloadingly high demand. In great depression we wandered back to the lab for what meager remains of our field food we could scrounge up. Several cups of coffee/chai later we summoned enough energy to clean up and complete our work for the night. But we are slow learners and it didn't stop us from trading breakfast for those extra 5 minutes of sleep the next morning. And we were gone for lunch again. Without Cadbury chocolate, we would never make it through the days!
| An old Spryte, now underwater, and serving as substrate for growth of marine animals like sponges and tunicates.
|| Part of the D8 Caterpillar tractor that is underwater in Winter Quarters Bay.
Lunch scroungers: Andrew is happy as long as he has coffee. Years of training have reduced him from a connoisseur to someone who smiles at freeze-dried. Jennifer digs some Pez out of a deep pocket, but they fail to capture her enthusiasm. Bob, always prepared for survival, has some compressed cornflakes in his backpack (a whole bowl of cereal in one bar). Mike goes through his desk drawer and finds a plate of eggs that are only 3 days old. Since they are the same grey color they were when he first got them, he figures they are okay to eat.
Dinner for real: Kathy is ready to dig in, but Jennifer's enthusiasm wanes at the sight of grey bacon. Bob has the variety plate, and Mike is in heaven with a rainbow of juices.
| Breakfast of champions: Echinacea, ibuprofen, coffee and chocolate.