title: In the darkness of the polar night, scallops keep on a steady rhythm.
abstract: Although the prevailing paradigm has held that the polar night is a period of biological quiescence, recent studies have detected noticeable activity levels in marine organisms. In this study, we investigated the circadian rhythm of the scallop Chlamys islandica by continuously recording the animal's behaviour over 3 years in the Arctic (Svalbard). Our results showed that a circadian rhythm persists throughout the polar night and lasts for at least 4 months. Based on observations across three polar nights, we showed that the robustness and synchronicity of the rhythm depends on the angle of the sun below the horizon. The weakest rhythm occurred at the onset of the polar night during the nautical twilight. Surprisingly, the circadian behaviour began to recover during the darkest part of the polar night. Because active rhythms optimize the fitness of an organism, our study brings out that the scallops C. islandica remain active even during the polar night.
authors: CNRS, UMR 5805 EPOC. Place du Dr. Peyneau, 33120, Arcachon, France.|Bordeaux University, UMR EPOC 5805 Place du Dr. Peyneau, 33120, Arcachon, France.
authors: Damien
authors: D
authors: Tran
authors: Bordeaux University, UMR EPOC 5805 Place du Dr. Peyneau, 33120, Arcachon, France.
authors: Mohamedou
authors: M
authors: Sow
authors: Akvaplan-niva, Fram center for Climate and the Environment, 9296 Tromso, Norway.|University Centre in Svalbard, Pb 156, N-9171 Longyearbyen, Norway.
authors: Lionel
authors: L
authors: Camus
authors: CNRS, UMR 5805 EPOC. Place du Dr. Peyneau, 33120, Arcachon, France.|Bordeaux University, UMR EPOC 5805 Place du Dr. Peyneau, 33120, Arcachon, France.
authors: Pierre
authors: P
authors: Ciret
authors: University Centre in Svalbard, Pb 156, N-9171 Longyearbyen, Norway.|UiT The Arctic University of Norway, Faculty of Biosciences, Fisheries and Economics, N-9037 Tromsø, Norway.
authors: Jorgen
authors: J
authors: Berge
authors: CNRS, UMR 5805 EPOC. Place du Dr. Peyneau, 33120, Arcachon, France.|Bordeaux University, UMR EPOC 5805 Place du Dr. Peyneau, 33120, Arcachon, France.
authors: Jean-Charles
authors: JC
authors: Massabuau