Uncharted (frozen) waters
By DR. JOSEPH TORRES
© St. Petersburg Times,
MARGUERITE BAY, Antarctica -- The search for concentrations of krill and krill predators took a turn for the better just after a turn for the worse.
We were in the middle of the bay, trawling our nets, when the winds came up strongly: about 45 knots. The combination of wind and rolling sea soon got too severe for us to work any longer.
To tow nets or use the instruments that are mounted in the hull of the vessel, such as depth sounders, we must hold our course. In these tough conditions, the only course we can maintain is directly into the wind, but above 35 knots, even that is dicey.
The wind speed continued to increase -- to more than 50 knots -- and we needed to move into a more protected area to continue our quest for krill, penguins, and seals. Our science party chose a small body of water named Lazarev Bay.
Besides being a shelter from the howling east wind, the little bay had three other attractors:
First, it was farther south than Marguerite Bay and, because of the shorter days there, we expected to find new ice.
Second, small islands are likely habitats for seal and penguins, who rest there while feeding.
Third, the area was nearly unexplored. There were no depth soundings on the chart in Lazarev Bay. What a feeling to go somewhere that few people have seen. We had many surprises in store.
We arrived before first light, which now is about 10:30 a.m. First, we discovered the charts we were using were inaccurate. The island that forms the southern lip of the bay was nearly 12 miles south of where it appeared on the chart. The island that forms the northern lip was about 5 miles south of its charted position. Also, we were finding many unmapped, small islands. Just the sort of situation that tends to make the captain of any boat very cautious.
Consider navigating fields of icebergs, sometimes in the dark, with a bad map -- you get a feeling for what our captain has to put up with.
On the first uncharted island, we found some Adelie penguins. Bill Fraser, our penguin expert, was able to attach satellite transmitters to two penguins there, and we now are getting data on where and when the birds are feeding. More was to come.
We guessed right about the ice. Certainly it was due to the shorter days in Lazarev Bay -- and maybe the lack of a deep canyon to bring in warm water from off the shelf.
Many older ice floes in the bay also were just the right-sized platform for a couple of seals and four intrepid seal biologists.
Our "target seal" is the crabeater seal, which feeds mainly on krill. It was originally named in the 19th century by seal hunters who saw its red scat and wrongly assumed it was eating crabs.
A moment here about the importance of satellite transmitters. Penguins and diving mammals are nearly impossible to follow; they are very mobile and spend a great deal of their time under water.
Satellite transmitters can give us information on an individual's location several times a day and, if they are equipped with the proper sensors, they can tell us how many dives a seal or penguin has made and the depth of each dive. Also, you can bet that the areas the penguins and crabeater seals visit most often are rich in krill.
We hope to see where our newly tagged birds and seals spendthe winter. If our penguin and seal biologists are lucky, the tags will stay on for months, giving them information on where the birds and mammals go during each change of season.
For our group from USF, Lazarev Bay provided our first opportunity to do a scientific dive in the Antarctic.
The krill larvae go right to the ice as soon as it is formed. Hundreds of krill, each less than three-quarters of an inch, could be found in the nooks and crannies of the slushy underside of the new ice.
It is quite lovely under there. The ice, just a couple inches thick at this time, appears illuminated. It is the beginning of a new environment, and the first residents have moved in.
We are still exploring whether the krill in the ice are doing better than the ones out in the open sea. Our algae biologists' early results suggest there is more for the krill to eat under there.
One last thing. Down in Lazarev Bay we reached the time of season when the sun no longer comes above the horizon. There is light, like a St. Petersburg sunset. We still had four hours or so of light, but it came in the form of a two-hour sunrise followed by a two-hour sunset. It was glorious.
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