In the Arctic, January 2014
All about there is an eerie silence only broken by the occasional faint howls of huskies in the distance. The snow has stopped falling and the clouds are slowly thinning; the twinkle of millions of stars across the Milky Way becoming ever more apparent.
The marine laboratory has been blacked out, the streetlamps leading to the pier are dark, even my head torch is dimmed red. I shuffle about in my clumsy Polar clothing. My backpack contains a sensitive light meter, especially designed for the job at hand. I point it towards the east and take a reading. Nothing. Zero light. We have to wait some more. It is cold, bitterly so and I crumple my toes in my boots in an attempt to get some warmth into them. And I wait for nothing very much continuous to happen: this is the life of a scientist de facto.
Then, very slowly, the full moon begins to rise. The land is gradually bathed with cold white light, which illuminates the tips of the snow covered hills and then creeps at a molluscan pace down to the glaciers that snake their way into the fjord.
The sea begins to shimmer and the snow around me twinkles and sparkles. The dogs howl feverishly like a lunar dawn chorus and as I gaze into the black fjord I know that something very big is stirring in the depths. I imagine denizens of the deep, aquatic werewolves on the run, as billions of tiny creatures start to move away from the moonlight. I hold my light meter high and it flickers to life – we have light! A collective cry goes out to man the action stations: grab your nets boys, gun the boats girls, throw the surveillance robots into the sea and rally the dive team. The time has come to catch those elusive werewolves of the deep!
Now this may all sound a little bit dramatic, but it is not really that far removed from the truth. I have joined an expedition to Ny Alesund on the western side of the Svalbard archipelago to help try and figure out what happens to animals, those tiny creatures of the deep or, more scientifically, zooplankton, at this time of year when there is virtually no daylight.
For some years now we have been gathering data from our acoustic sensors on the seabed which have shown something quite remarkable. At a time when zooplankton should be in hibernation, more properly known as diapause, they are migrating as regular as clockwork up and down in the water. Questions immediately arise: There are many kinds of zooplankton, so which ones are doing the migrating? Why are they bothering to migrate in the first place? And, perhaps most importantly, what are the implications of such migrations to the Arctic ecosystem since this is, after all, the largest by mass daily migration on the planet?
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Sediment trap for collecting zooplankton poo.
SAMS scientists Colin Griffiths (L) & Finlo Cottier (R) get down to business.
Image: K.S. Last.
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Good questions are the cornerstone to great science and Jorgen Berg, the scientific leader of the CIRCA project likes good questions. But as we know from my lunar light measurements, science can be slow and tedious. It takes a long time to be sure that the data you have painstakingly collected actually reflects what might be going on in the real world and ideally you need to know what you are doing. So Jorgen collected a team of scientists from many countries, experts in many different disciplines to try and answer such fundamental questions.
The zooplankton are well known to migrate in response to light at a time when the sun is above the horizon. They feed on plants or algae in the surface waters at night and then migrate into the depths during the day, the hypothesis is that they do this to avoid predators and follow isolumes or light gradients as they migrate. But what about during December and January in the Arctic when only moonlight, starlight and on occasion, the fantastic light show of the aurora borealis light the sky? The most obvious light candidate with reference to overall intensity is moonlight and when we make correlations between the migration intensity of the zooplankton from our acoustic instruments and the phase of the moon with its angle above the horizon, the result is a strong relationship between the two.
The list of jobs of the CIRCA project is hugely diverse and tasks span many years. Julie Grenvald, a PhD student (from UNIS, the University Centre in Svalbard), is painstakingly collecting zooplankton from different depths and then identifying and counting the animals she finds. Laura Hobbs, also a PhD student (from the Scottish Association of Marine Science) is processing acoustic data from all over the Arctic Sea, including the North Pole, to determine the extent of the migrations. And the postdoc Gérald Darnis (from Akvaplan-niva AS, Tromsø) is very carefully catching zooplankton excrement, which you may think is rather an odd use of time. But quite the contrary, the composition and amount of zooplankton faeces can inform us about the amount of carbon which is captured by the animals in the surface waters and transported to the deep sea. This, would you believe, may provide an important piece of data in informing future climate predictions.
And what am I doing in all this apart from switching on a light meter? What small piece of the jigsaw am I attempting to piece together? All organisms that we know of possess a biological clock. This clock enables animals and plants to predict a future cyclic change in their environment. Our own circadian clock sets the tempo of many physiological and behavioural processes and most of the time we are not even aware of it, unless we fly across many time zones and experience jet-lag.
Of particular interest is that Arctic zooplankton that are responding to the daily rising and setting of the moon may have a very different kind of a clock, or even a special circadian one that can not only tell the time of the rising and setting of the sun but, during the winter months at least, the rising and setting of the moon. Whereas the sun takes precisely 24 hours, the moon takes about an hour longer. So my experiments require me to catch animals and place them in chambers in complete darkness and constant temperature and then measure swimming activity. If the clock exists then the animals will be active spontaneously every 25 hours and will show that moonlight can indeed control the denizen's clock. However, my experiments will also tell us more about the ancestral proto-clock that first evolved in algae ~2 billion years ago on a planet that was very different from today and where the influence of the moon cycle was much stronger, to the extent that a day may have been only four hours long, but that's another story.
So now the stations have been manned, the nets filled and the robots recovered, the time has come to work up the data. The light meter is packed and my toes are truly cold. The moon is gradually sinking beyond the hills and the few hours of light give way to complete darkness again. Time to head into the warmth of the laboratory and, albeit slowly, try to figure out what those elusive werewolves of the deep are up to.
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Links:
http://www.sams.ac.uk/kim-last/
http://www.mare-incognitum.no/index.php/circa
http://www.sams.ac.uk/finlo-cottier/panarcive
http://www.sams.ac.uk/news-room/new-project-to-investigate-arctic-plankton-dynamics/
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