title: Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice.
abstract: The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m-2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean.
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Philipp
authors.initials: P
authors.lastname: Assmy
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Mar
authors.initials: M
authors.lastname: Fernández-Méndez
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Pedro
authors.initials: P
authors.lastname: Duarte
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Amelie
authors.initials: A
authors.lastname: Meyer
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.|Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway.
authors.forename: Achim
authors.initials: A
authors.lastname: Randelhoff
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Mundy
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Lasse M
authors.initials: LM
authors.lastname: Olsen
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Hanna M
authors.initials: HM
authors.lastname: Kauko
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Allison
authors.initials: A
authors.lastname: Bailey
authors.affiliation: Institute of Marine Research, 9019 Tromsø, Norway.
authors.forename: Melissa
authors.initials: M
authors.lastname: Chierici
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Lana
authors.initials: L
authors.lastname: Cohen
authors.affiliation: Department of Physics and Technology, Faculty of Science and Technology, UiT The Arctic University of Norway, 9037 Tromsø, Norway.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Doulgeris
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Jens K
authors.initials: JK
authors.lastname: Ehn
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Agneta
authors.initials: A
authors.lastname: Fransson
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gerland
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.|Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway.
authors.forename: Haakon
authors.initials: H
authors.lastname: Hop
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Hudson
authors.affiliation: Norwegian Meteorological Institute, 9239 Tromsø, Norway.
authors.forename: Nick
authors.initials: N
authors.lastname: Hughes
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Polona
authors.initials: P
authors.lastname: Itkin
authors.affiliation: Centre for Autonomous Marine Operations and Systems, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway.|University Centre in Svalbard, Post box 156, 9171 Longyearbyen, Norway.
authors.forename: Geir
authors.initials: G
authors.lastname: Johnsen
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: King
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Boris P
authors.initials: BP
authors.lastname: Koch
authors.affiliation: LOCEAN, UMR 7159, CNRS/UPMC/MNHN/IRD, Pierre and Marie Curie University, Paris cedex, France.
authors.forename: Zoe
authors.initials: Z
authors.lastname: Koenig
authors.affiliation: Institute of Oceanology, Polish Academy of Sciences, 81-712 Sopot, Poland.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Kwasniewski
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Laney
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Nicolaus
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Alexey K
authors.initials: AK
authors.lastname: Pavlov
authors.affiliation: U.S. Army, Cold Regions Research and Engineering Laboratory, Hanover, NH 03755, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Polashenski
authors.affiliation: LOCEAN, UMR 7159, CNRS/UPMC/MNHN/IRD, Pierre and Marie Curie University, Paris cedex, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Provost
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Anja
authors.initials: A
authors.lastname: Rösel
authors.affiliation: Centre for Autonomous Marine Operations and Systems, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Marthe
authors.initials: M
authors.lastname: Sandbu
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.|Institute of Environmental Physics, University of Bremen, 28334 Bremen, Germany.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Spreen
authors.affiliation: Bjerknes Centre for Climate Research, 5007 Bergen, Norway.|Geophysical Institute, University of Bergen, 5007 Bergen, Norway.
authors.forename: Lars H
authors.initials: LH
authors.lastname: Smedsrud
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Arild
authors.initials: A
authors.lastname: Sundfjord
authors.affiliation: Department of Physics and Technology, University of Bergen, 5007 Bergen, Norway.
authors.forename: Torbjørn
authors.initials: T
authors.lastname: Taskjelle
authors.affiliation: Institute of Oceanology, Polish Academy of Sciences, 81-712 Sopot, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Tatarek
authors.affiliation: Institute of Oceanology, Polish Academy of Sciences, 81-712 Sopot, Poland.
authors.forename: Jozef
authors.initials: J
authors.lastname: Wiktor
authors.affiliation: Norwegian Meteorological Institute, 9239 Tromsø, Norway.
authors.forename: Penelope M
authors.initials: PM
authors.lastname: Wagner
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Anette
authors.initials: A
authors.lastname: Wold
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Harald
authors.initials: H
authors.lastname: Steen
authors.affiliation: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway.
authors.forename: Mats A
authors.initials: MA
authors.lastname: Granskog
mesh_terms: D001110:Arctic Regions; D017554:Carbon Compounds, Inorganic / Q000032:analysis; D005068:Eutrophication; D058087:Haptophyta / Q000254:growth & development; D046448:Ice Cover; D009566:Nitrates / Q000032:analysis; D010839:Phytoplankton / Q000254:growth & development*; D063809:Satellite Imagery; D012621:Seasons
chemical_list: D017554:Carbon Compounds, Inorganic; D009566:Nitrates