Saturday 19 October 2002

John Oliver writes:

Today Stacy and John made their first dive into the cold, dark, but still very clear waters of McMurdo Sound. This was also their checkout dive. The dive locker is run by Rob Robbins, a highly experienced, competent, and fun diver. Rob did many construction dives around McMurdo Station building a rock jetty, a sewer outfall, and more. He has a personality and approach to diving and running a diving program that is similar to the dive officer at Moss Landing, John Heine. Rob is the best dive supervisor who has ever worked on the ice. Today he reminded us of gear we almost left behind and what order you must put the gear on to actually get into the water. Much of the diving equipment comes from his dive locker. He keeps the gear maintained, tests and procures new technology, and teaches us how to use it. In our case he mostly reminds us, but this is a wonderful and useful service. We have attended many of checkouts this first week (vehicles, radios, sea ice, survival packs, airplanes, and more), but nothing has been so useful as Rob's diving checkout. He gets us into the water successfully and safely, providing information or other help we may need.

This year we are all using dry gloves. What a joy. Our hands are dry and warm. John's feet were cold, which is easy to fix with another pair of socks. Cold hands can limit your time underwater more often than any other problem- usually with the greatest pain and discomfort. Our hands are warm! We dove at the rock jetty, where the seawater intake is located. Seawater is pumped to a plant to extract salts and make freshwater for the station. The bottom around the jetty is one of the few regions covered with muddy sediment that still contains a healthy community of infaunal invertebrates. The largest region of soft-sediment near the station is in and around Winter Quarters Bay, which is contaminated with oil, other hydrocarbons, heavy metals, and raw sewage. The bottom communities are highly degraded here. The rock jetty itself covers a fairly large area of local soft bottom, running perpendicular to the shore to about 70 feet. Many sessile invertebrates have settled on the rocks and fish use the artificial reef as well. Still, the natural soft bottom, sponge spicule community, and gravel/cobble habitats harbor richer natural ecosystems. The dive went well. We were slightly overwhelmed at the layers of underwear, thick diver suit, three hoods, two regulators, and 40 pounds of weight belt.

After the dive, Stacy and John helped drill seven dive holes in the sea ice in front of the station. It took only two hours. The mobile drill is one of the most important advances in polar technology providing many access holes to the marine environment. Before the drill, holes were made by chain saws and by blasting with dynamite. This is labor intensive and it can take many hours just to get one hole. As a result, divers often had only one hole for access to large underwater areas. Now we have many holes to service the same bottom area. This makes the diving much more safe, productive, and fun. Tide cracks were also a primary site for sampling the water and the sea floor, but they only occur in a few locations and often need to be opened larger with a chain saw as well. Before the drill, we might have a dozen holes in the ice for scientific exploration, including cracks. Now we can have many dozens with more time available for research or just enjoying the place. Today there were high clouds, but no significant wind, and you can still see the landscape more than 60 miles away. The weather has been exceptionally calm for October. Dan, Andrew, and Aaron are still in survival school, looking forward to Rob's checkout.