by Piter Kehoma Boll
Today’s Friday Fellow comes swimming tinily through the freezing waters in the north. It is a small crustacean, more precisely a copepod, and its name is Calanus glacialis. It lacks a common name, but I adapted it as the “glacial calanus”.
Found in the Arctic Ocean and the northernmost areas of the Atlantic and Pacific Oceans, the glacial calanus is one of the most abundant polar species of copepods and one of the main components of the zooplancton in this region. As a result, it is an important food source for other animals, such as fish, birds and even whales.
The life cycle of the glacial calanus varies from 1 to 3 years and depends on the temperature and food availability. Most of its development occurs in summer, when the water is warmer and there is plenty of food, which for our fellow consists mainly of algae, such as diatoms. In autumn, the glacial calanus starts to accumulate lipids and then migrates downwards to deep waters and becomes dormant to survive the long, dark and food-poor winter.
As its life cycle depends on such seasonal variations, global warming may have profound impacts on the populations of the glacial calanus and on that of other species that depend on it as food.
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Kosobokova, K. N. 1999. The reproductive cycle and life history of the Arctic copepod Calanus glacialis in the White Sea. Polar Biology 22:254–263. DOI: 10.1007/s003000050418.
Søreide, J. E.; Leu, E.; Berge, J.; Graeve, M.; Falk-Petersen, S. 2010. Timing of blooms, algal food quality and Calanus glacialis reproduction and growth in a changing Arctic. Global Change Biology 16:3154–3163. DOI: 10.1111/j.1365-2486.2010.02175.x
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