English
norskBlar i forfatter "Assmy, Philipp"
Viser treff 1-18 av 18
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Arctic Observations Identify Phytoplankton Community Composition as Driver of Carbon Flux Attenuation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-24)The attenuation coefficient <i>b</i> is one of the most common ways to describe how strong the carbon flux is attenuated throughout the water column. Therefore, <i>b</i> is an essential input variable in many carbon flux and climate models. Marsay et al. (2015, <a href=https://doi.org/10.1073/pnas.1415311112>https://doi.org/10.1073/pnas.1415311112</a>) proposed that the median surface water temperature ... -
Ballasting by cryogenic gypsum enhances carbon export in a Phaeocystis under-ice bloom
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-16)Mineral ballasting enhances carbon export from the surface to the deep ocean; however, little is known about the role of this process in the ice-covered Arctic Ocean. Here, we propose gypsum ballasting as a new mechanism that likely facilitated enhanced vertical carbon export from an under-ice phytoplankton bloom dominated by the haptophyte Phaeocystis. In the spring 2015 abundant gypsum crystals ... -
Carbon export in the seasonal sea ice zone north of Svalbard from winter to late summer
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-21)Phytoplankton blooms in the Arctic Ocean's seasonal sea ice zone are expected to start earlier and occur further north with retreating and thinning sea ice cover. The current study is the first compilation of phytoplankton bloom development and fate in the seasonally variable sea ice zone north of Svalbard from winter to late summer, using short-term sediment trap deployments. Clear seasonal patterns ... -
Changes in Sea-Ice Protist Diversity With Declining Sea Ice in the Arctic Ocean From the 1980s to 2010s
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-06)The large declines in Arctic sea-ice age and extent over the last decades could have altered the diversity of sea-ice associated unicellular eukaryotes (referred to as sea-ice protists). A time series from the Russian ice-drift stations from the 1980s to the 2010s revealed changes in community composition and diversity of sea-ice protists from the Central Arctic Ocean. However, these observations ... -
Earlier sea-ice melt extends the oligotrophic summer period in the Barents Sea with low algal biomass and associated low vertical flux
(Journal article; Tidsskriftartikkel, 2023-03-27)The decrease in Arctic sea-ice extent and thickness as a result of global warming will impact the timing, duration, magnitude and composition of phytoplankton production with cascading effects on Arctic marine food-webs and biogeochemical cycles. Here, we elucidate the environmental drivers shaping the composition, abundance, biomass, trophic state and vertical flux of protists (unicellular eukaryotes), ... -
Feeding at the front line: Interannual variation in the use of glacier fronts by foraging black-legged kittiwakes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-28)Tidewater glacier fronts can represent important foraging areas for Arctic predators. Their ecological importance is likely to change in a warmer Arctic. Their profitability and use by consumers are expected to vary in time, but the underlying mechanisms driving such variation remain poorly known. The subglacial plume, originating from meltwater discharge, is responsible for the entrainment and ... -
The future of Arctic sea-ice biogeochemistry and ice-associated ecosystems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-27)The Arctic sea-ice-scape is rapidly transforming. Increasing light penetration will initiate earlier seasonal primary production. This earlier growing season may be accompanied by an increase in ice algae and phytoplankton biomass, augmenting the emission of dimethylsulfide and capture of carbon dioxide. Secondary production may also increase on the shelves, although the loss of sea ice exacerbates ... -
The importance of turbulent ocean–sea ice nutrient exchanges for simulation of ice algal biomass and production with CICE6.1 and Icepack 1.2
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-31)Different sea ice models apply unique approaches in the computation of nutrient diffusion between the ocean and the ice bottom, which are generally decoupled from the calculation of turbulent heat flux. A simple molecular diffusion formulation is often used. We argue that nutrient transfer from the ocean to sea ice should be as consistent as possible with heat transfer, since all of these fluxes ... -
Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-19)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 ... -
Panel-based Assessment of Ecosystem Condition of Norwegian Barents Sea Shelf Ecosystems
(Research report; Forskningsrapport, 2023-03-16)The System for Assessment of Ecological Condition, coordinated by the Norwegian Environment Agency, is intended to form the foundation for evidence-based assessments of the ecological condition of Norwegian terrestrial and marine ecosystems not covered by the EU Water Framework Directive. The reference condition is defined as “intact ecosystems”, i.e., a condition that is largely unimpacted by modern ... -
Panel-based Assessment of Ecosystem Condition of Norwegian Barents Sea Shelf Ecosystems - Appendices
(Research report; Forskningsrapport, 2023-03-16) -
Pelagic Ecosystem Characteristics Across the Atlantic Water Boundary Current from Rijpfjorden, Svalbard, to the Arctic Ocean during Summer (2010-2014)
(Journal article; Peer reviewed, 2019-04-09)The northern coast of Svalbard contains high-arctic fjords, such as Rijpfjorden (80°N 22°30′E). This area has experienced higher sea and air temperatures and less sea ice in recent years, and models predict increasing temperatures in this region. Part of the West Spitsbergen Current (WSC), which transports relatively warm Atlantic water along the continental slope west of Svalbard, bypasses these ... -
A review of the scientific knowledge of the seascape off Dronning Maud Land, Antarctica
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-29)Despite the exclusion of the Southern Ocean from assessments of progress towards achieving the Convention on Biological Diversity (CBD) Strategic Plan, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has taken on the mantle of progressing eforts to achieve it. Within the CBD, Aichi Target 11 represents an agreed commitment to protect 10% of the global coastal and ... -
Sea ice thermohaline dynamics and biogeochemistry in the Arctic Ocean: Empirical and model results
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-11)Large changes in the sea ice regime of the Arctic Ocean have occurred over the last decades justifying the development of models to forecast sea ice physics and biogeochemistry. The main goal of this study is to evaluate the performance of the Los Alamos Sea Ice Model (CICE) to simulate physical and biogeochemical properties at time scales of a few weeks and to use the model to analyze ice algal ... -
Seasonal plankton dynamics in Kongsfjorden during two years of contrasting environmental conditions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-24)Seasonal plankton time-series data are presented from Kongsfjorden from two years with contrasting environmental conditions. Kongsfjorden (west coast of Spitsbergen – 79°N) integrates inputs from Atlantic and Arctic waters, and glacier run-off, and is thus a prime location to study impacts on ecosystem dynamics of key environmental drivers that are relevant across the Arctic. Despite extensive ... -
The seeding of ice algal blooms in Arctic pack ice: The multiyear ice seed repository hypothesis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-03)During the Norwegian young sea ICE expedition (N-ICE2015) from January to June 2015 the pack ice in the Arctic Ocean north of Svalbard was studied during four drifts between 83° and 80°N. This pack ice consisted of a mix of second year, fi rst year, and young ice. The physical properties and ice algal community composition was investigated in the three different ice types during the ... -
Tidewater glaciers and bedrock characteristics control the phytoplankton growth environment in a fjord in the arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-31)Meltwater discharge from tidewater glaciers impacts the adjacent marine environment. Due to the global warming, tidewater glaciers are retreating and will eventually terminate on land. Yet, the mechanisms through which meltwater runoff and subglacial discharge from tidewater glaciers influence marine primary production remain poorly understood, as data in close proximity to glacier fronts are scarce. ... -
Winter storms accelerate the demise of sea ice in the Atlantic sector of the Arctic Ocean
(Journal article; Peer reviewed, 2019-06-25)A large retreat of sea-ice in the ‘stormy’ Atlantic Sector of the Arctic Ocean has become evident through a series of record minima for the winter maximum sea-ice extent since 2015. Results from the Norwegian young sea ICE (N-ICE2015) expedition, a five-month-long (Jan-Jun) drifting ice station in first and second year pack-ice north of Svalbard, showcase how sea-ice in this region is frequently ...
