Tonight Hugh Miller is the happiest little cameraman in Antarctica. Hugh has been moonlighting – if such a thing is possible in 24 hour daylight. By day he has been doing the underwater lighting for me and by night he has been finishing the build on his latest underwater time-lapse rig. Simply, it’s a couple of digital cameras, in underwater housings, that take pictures every few seconds – when you play back the pictures the whole scene is sped up hundreds of times. He finished it 3 days ago and today he captured in time-lapse a “Brinicle” growing.
6 weeks ago I’d never heard of a Brinicle either. So here is the science bit. They look like giant underwater icicles and hang from underneath the sea-ice. They can be as big as a foot wide and 30 feet long. They grow because when the sea-ice gets cold and freezes a very salty brine is also formed which does not freeze – don’t ask why, I did and regretted it. The Brine is heavier than sea water so starts to flow down through the pores and cracks in the sea-ice. In places it flows out so thick you can see it like a sort of underwater haze. Because the Brine is colder than the water it starts to freeze it. When conditions are right this freezing starts forming a tube. The Brine flows through the centre of the tube and freezes water as it flows out the end. And that is how a brinicle forms.
There are lots of little ones growing all over the place, and a few big dead ones, but we didn’t find a large one in the process of growing until a week ago. It was 8 feet long with brine pouring out of it. Hugh and I filmed it with my camera and then came back to the hut to warm up. We went back in about 2 hours later. It had grown by 2 foot, hit the seabed and then formed a river of ice about a foot wide running 25feet down the slope. It was carnage. Urchins and starfish had been frozen into the ice river. Some were still alive but most had already snuffed it. It was amazing and we got good coverage. That evening we dared to talk of another that we could cover with the Time-lapse gear – not yet, at that time, completely built yet.
This morning, in almost exactly the same spot, we found another. It was the first time that Hugh’s time-lapse rig had ever been in sea water. The Brinicle we found was about 3 feet from the seabed and flowing really well. Hugh and I swam the cameras and lights across. Hugh pressed go. We came back 3 hours later. It had done the same as the first – hit the sea bed and made an Ice river down the slope. Hugh reset the cameras and pressed go again. We went in late and dragged the cameras out. Hugh has just rendered the image sequence into short films. They are rough but the results are amazing. It looks like a witches spell. A dangerous finger of growing ice extends down and captures the poor little urchins and starfish in an icy web. Some make it away just in time but most are frozen in. It is one of the wildest weirdest things I have ever seen in wildlife. This is going to be a sweeeeeet little sequence!