Who said that the polar night is nap time? According to recent research, the polar night has a relatively high biological activity, disproving the common belief that everything goes to sleep during the full-night cycle in polar regions. If you ask my small critter, life goes on like usual even if the lights are off! You can think of them as teenagers at New Year’s Eve instead of grandparents getting ready for bed…
And I think that this is very interesting! So here I am, studying small copepods (small crustaceans at the base of the food web) during this Polar Night cruise. My aim is to gain an insight of their reproductive output during winter and relate it to the distribution of their different life stages.
The big picture is to understand how small copepods’ ecology differs from the bigger copepod species. It is believed that small copepods will adapt more easily than the bigger species to a warming Arctic. This is due to their different ways of living. Most big copepods hibernate for winter and possess a long life cycle adapted to the strong seasonality of the Arctic. It is predicted that in the future, the Arctic algal bloom (the food source of copepods) will arrive earlier in the spring and there will be a second autumnal bloom. Therefore, it could prove challenging to adapt to an earlier food supply when their life cycle is timed to a later productive season.
On the other hand, small copepods like Oithona similis and Microcalanus sp. have a more flexible biology, meaning they can live in a wide range of temperatures (they are found throughout all of the world’s ocean). They have shorter life cycles, but reproduce year round which means that their offspring can take advantage of any productive food event.
To help me I have Peter Glad, the Filtration Guru, whom I want to thank for his invaluable help during the cruise. Peter helped me filter the water at our different sampling stations. Water filtration gives an indication of the amount of food available to small copepods, both algae and detritus. The amount of food available can then be linked to their metabolism and their reproductive output.
Coralie Barth-Jensen (PhD candidate, UiT)