As part of the Southern Ocean - Continuous Plankton Recorder (SO-CPR) program, zooplankton samples have been annually collected on a dedicated Polarstern voyage to the Antarctic continent and back over the last 4 seasons or so, including this one, and I am the responsible scientist. Zooplankton are sensitive to environmental parameters such as temperature, movement of currents and water quality. Due to their sensitivity, short life spans and fast growth rates plankton populations respond rapidly to environmental change, and consequently make excellent biological indicators for climate change and pollution.
The Continuous Plankton Recorder, commonly referred to as a CPR can collect surface or near-surface zooplankton at normal ship speed during a voyage. CPR sampling does not usually interfere with any other projects, and because of this it is a very versatile piece of equipment. The unit, which is known as “the fish” among the crew, is usually towed about 100 metres astern of the ship for approximately 450 nautical miles at a time.
So far, the CPR has been towed 3 times between 45°S and nearly 60°S. This came to an abrupt stop last night. The CPR doesn’t fare too well with meeting ice at sea. Ice is much harder, and I know who will win any encounter! Yesterday, Captain Pahl said to me that we should be meeting the first of the pack ice later in the evening. So, feeling quite diligent, I decided to stay up for as long as I could last night. Sure enough, not long before midnight I first heard the characteristic sound of ice scraping along the sides of the ship. And of course when I looked out of my cabin window, there was ice for as far as I could see. We had encountered a wide band of pack ice, and so it was time to retrieve my gear to safety. Some of the deck crew came down straight away, and in no time the CPR was back on board. Just as well, as more and more of pack ice loomed in the distance.
I then extracted the gauze with the zooplankton on it and preserved the animals for analysis after the voyage at my laboratory in Kingston, Tasmania. Then it was off to bed, in the early hours of the morning, and the last thing I remember before falling asleep was the sound of ice scraping along the hull! I will be looking forward to tomorrow, where we will hopefully be in among some impressive pack ice, photographing not only the seascapes but the array of animals we hope to see hauled out onto the ice. I can’t wait!!!
John Kitchener, Australian Antarctic Division
Photos: V. Wadley, Australian Antarctic Division and Census of Antarctic Marine Life