Body clocks keep ticking in the high Arctic Ocean

Night or day the bodyclocks of tiny marine organisms keep ticking regardless, scientists have discovered.

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Scientists have discovered how the bodyclocks of tiny marine life in the Arctic summer keep ticking even when day becomes indistinguishable from night.

When the midnight sun beats down, it seems the biological clocks of minuscule marine organisms carry on regardless despite permanent daylight.

Marine biologists from Oban  studying how climate change affects the Arctic found that the genes of tiny shrimp-like animal plankton called copepods keep ticking even hundreds of metres under snow-covered sea-ice.

The copepod Calanus finmarchicus with functioning biological clock. Photograph: Dr Kim Last of SAMS.

Indications are that animals are using other signs such as tides to set their body clocks.

Researchers had previously suspected that the daily cycles of biology would cease during the Arctic summer when the sun is permanently above the horizon and day and night become indistinguishable. They expected the lack of a light-dark trigger to affect the proper functioning of the circadian clocks that affect tourists and marine plankton alike.

Project leader Dr Kim Last from the Scottish Association for Marine Science (SAMS) at Dunstaffnage, said: ‘It’s simply astonishing to know that these tiny copepods have a functioning circadian clock when they can be tens to hundreds of metres underwater and sea-ice at a time when there is virtually no difference between day and night.’

Researchers also found while in the southern Arctic, circadian clock genes generally cycled daily, in the north and only a few hundred miles from the North Pole, their clock had changed.

Lukas Hüppe from the Helmholtz Institute for Functional Marine Biodiversity and the Alfred Wegener Institute in Germany who was the lead author of the paper published  in The Royal Society Biology Letters, said: ‘We noticed that the circadian clock had changed from following a 24 hour cycle to a 12 hour cycle. We assume this means that the animals are using other signals to set their clock which may include the tides.’

Co-author of the paper Dr David Wilcockson from the University of Aberystwyth added: ‘We know that many intertidal marine organisms have tidal as well as circadian clocks. These Arctic copepods may have the ability to modify or switch between clocks depending on where they end up.’

Copepods are essential to the Atlantic and Arctic food webs because they store fat and are the main food source for fish and many sea birds and whales. The findings will provide clues on their survival at very high latitudes.

This work was supported by the CHASE project, part of the Changing Arctic Ocean programme, jointly funded by the UKRI Natural Environment Research Council and the German Federal Ministry of Education and Research. Ocean expedition time was supported by the CAO Arctic PRIZE project.