John Oliver writes:

31 October 02

Today was a special dive, a working vacation. We went to Cape Evans about 25 miles north along a flagged road across the sea ice. Another research group has a dive hut here above 60 feet of water. Aaron had us collect fish that were tagged by a New Zealand fish biologist, John McDonald. He trapped 800 fish here, injected a florescent chemical into them, and released them to the same bottom habitat two years ago. The chemical has no negative impact on the fish, but is taken up into bone as the fish grows leaving a florescent marker. Fish ears often have distinct growth rings that are usually laid down each year. Since the florescent tracer is rapidly lost from the fish except in bone, the tracer will let John verify if the ear rings are made each year. If so, he can count the total number of rings in fishes of different sizes and sexes and determine how long they live. The local fishes should have distinct annual growth rings because the Antarctic is a highly seasonal environment with summer pulses of food and long periods of dark with little or no plant production.

We located and collected about 40 fish tagged by John. Most of us got cold underwater. But it was worth it. Cape Evans has the most light reaching the sea floor, because the sea ice is only a year old (6 feet thick). The ice is two years old at all our other diving sites(10-15 feet). The light lets you see so much more of the underwater seascapes. There are several small canyons with steep rocky walls dropping from 60 to 80 feet, lots of small red algae because of the improved light, and zillions of sea stars, urchins, and giant nemertean worms (the biggest are over 6 feet long). There was also a large number of zooplankton in the water: big and little jellyfish, siphonophores, ctenophores, and lots of pteropods. The bigger jellyfish were covered with pelagic amphipods catching a ride south. There is speculation that the giant ice bergs wedged around the entrance to McMurdo Sound are modifying regional water currents, and that the plankton is coming from an open water area due north. The usual current pattern brings plankton from the east along the face of Ross Ice Shelf and then south into the sound. Two state-sized ice bergs block this route and reach over 300 m below the sea surface. This is another good idea from the most experienced biologist on the ice, Art DeVries, a living Antarctic library.

After the dive, we visited Scott's winter hut at Cape Evans- a historical monument. The stable still has a stack of seal blubber collected almost 100 years ago. Its frozen solid, but will stink to high heaven when summer temperatures permit a thaw. The main living quarters are full of old cans, bottles, clothing, and all sorts of scientific gear. It looks very inhospitable now, but the old pictures show a warm, functional shelter- full of life. The hut is still excellent shelter from the wind, which was strong all day. We get home in time for dinner. Halloween will be celebrated this Saturday on 2 Nov. at McMurdo Station. There are hot showers, saunas, telephones, TV's, and a world class laboratory.