A long-standing Antarctic tradition is to celebrate the winter solstice with a rest from work on the shortest day, and have a party. Importantly, all the bases send each other greetings, a nice way of maintaining the sense of international cooperation and friendship that the Antarctic Treaty encourages. We even got a letter from the US President (though he doesn’t mention the importance of fish research, I’ll have to have a word about that…).
Another tradition is to jump into the sea (approximately -1.5oC) – the Polar Plunge. While hands get sensitized to cold by constant exposure, the rest of the body becomes more tolerant (not all that tolerant, however; the sea is breathtakingly cold!!) so despite little daylight outdoor work goes on around the base.
This is the last week of experiments, and the final piece of the puzzle is falling into place. We’ve demonstrated cardiac limitations facing the icefish – poor ability to cope with either increased pressure or temperature – now we complement that with investigating vascular limitations. Given the very large heart necessary to pump huge quantities of blood around the body, we reasoned that they rely more on tissue perfusion than diffusion to supply adequate oxygenation (unlike almost all other vertebrates). It follows that their vessel diameter (smooth muscle tone) is probably not as well regulated as other fish – and that is so. They respond to a reduced range of vasoactive substances, and require higher concentrations to elicit a response: they are wired to avoid hypertension and so prevent heart failure when under stress!
The last fishing trip was almost a disaster. Having caught a load of fish in terrible weather, it looked for a long time like our exhausted companions would not be able to land the catch, as bad weather had driven too much ice into the bay for the ship to dock.
There were also people due to leave base, and for a while it looked like the ship would have to head North leaving them behind and releasing our fish on the way! However, the Captain used bow thrusters to spin the boat on its axis and clear some ice, while our boatman used a lot of skill (and patience) to navigate though the local fused pancake ice. A close call!