title: Is Ambient Light during the High Arctic Polar Night Sufficient to Act as a Visual Cue for Zooplankton?
abstract: The light regime is an ecologically important factor in pelagic habitats, influencing a range of biological processes. However, the availability and importance of light to these processes in high Arctic zooplankton communities during periods of 'complete' darkness (polar night) are poorly studied. Here we characterized the ambient light regime throughout the diel cycle during the high Arctic polar night, and ask whether visual systems of Arctic zooplankton can detect the low levels of irradiance available at this time. To this end, light measurements with a purpose-built irradiance sensor and coupled all-sky digital photographs were used to characterize diel skylight irradiance patterns over 24 hours at 79°N in January 2014 and 2015. Subsequent skylight spectral irradiance and in-water optical property measurements were used to model the underwater light field as a function of depth, which was then weighted by the electrophysiologically determined visual spectral sensitivity of a dominant high Arctic zooplankter, Thysanoessa inermis. Irradiance in air ranged between 1-1.5 x 10-5 μmol photons m-2 s-1 (400-700 nm) in clear weather conditions at noon and with the moon below the horizon, hence values reflect only solar illumination. Radiative transfer modelling generated underwater light fields with peak transmission at blue-green wavelengths, with a 465 nm transmission maximum in shallow water shifting to 485 nm with depth. To the eye of a zooplankter, light from the surface to 75 m exhibits a maximum at 485 nm, with longer wavelengths (>600 nm) being of little visual significance. Our data are the first quantitative characterisation, including absolute intensities, spectral composition and photoperiod of biologically relevant solar ambient light in the high Arctic during the polar night, and indicate that some species of Arctic zooplankton are able to detect and utilize ambient light down to 20-30m depth during the Arctic polar night.
authors.affiliation: University of Delaware, School of Marine Science & Policy, 700 Pilottown Rd., Lewes, Delaware, United States of America.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Cohen
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway; Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037, Tromsø, Norway.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Berge
authors.affiliation: University of Delaware, School of Marine Science & Policy, 700 Pilottown Rd., Lewes, Delaware, United States of America.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Moline
authors.affiliation: Applied Underwater Robotics Lab, Depts of Biology and Marine Technology, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
authors.forename: Asgeir J
authors.initials: AJ
authors.lastname: Sørensen
authors.affiliation: Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll PA37 1QA, Scotland, United Kingdom.
authors.forename: Kim
authors.initials: K
authors.lastname: Last
authors.affiliation: Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037, Tromsø, Norway; Akvaplan-niva A/S, Fram Centre, 9296, Tromsø, Norway.
authors.forename: Stig
authors.initials: S
authors.lastname: Falk-Petersen
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway; Akvaplan-niva A/S, Fram Centre, 9296, Tromsø, Norway.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Renaud
authors.affiliation: Akvaplan-niva A/S, Fram Centre, 9296, Tromsø, Norway.
authors.forename: Eva S
authors.initials: ES
authors.lastname: Leu
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway; Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037, Tromsø, Norway.
authors.forename: Julie
authors.initials: J
authors.lastname: Grenvald
authors.affiliation: Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll PA37 1QA, Scotland, United Kingdom.
authors.forename: Finlo
authors.initials: F
authors.lastname: Cottier
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway; University of Delaware, School of Marine Science & Policy, 700 Pilottown Rd., Lewes, Delaware, United States of America.
authors.forename: Heather
authors.initials: H
authors.lastname: Cronin
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Menze
authors.affiliation: Applied Underwater Robotics Lab, Depts of Biology and Marine Technology, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
authors.forename: Petter
authors.initials: P
authors.lastname: Norgren
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway; Akvaplan-niva A/S, Fram Centre, 9296, Tromsø, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Varpe
authors.affiliation: Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037, Tromsø, Norway.
authors.forename: Malin
authors.initials: M
authors.lastname: Daase
authors.affiliation: Akvaplan-niva A/S, Fram Centre, 9296, Tromsø, Norway.
authors.forename: Gerald
authors.initials: G
authors.lastname: Darnis
authors.affiliation: The University Centre in Svalbard, 9171, Longyearbyen, Norway; Applied Underwater Robotics Lab, Depts of Biology and Marine Technology, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
authors.forename: Geir
authors.initials: G
authors.lastname: Johnsen
mesh_terms: D000818:Animals; D001110:Arctic Regions; D008027:Light; D008954:Models, Biological; D009792:Oceans and Seas; D015048:Zooplankton / Q000502:physiology*