scholarly journals The coccolithophores <i>Emiliania huxleyi</i> and <i>Coccolithus pelagicus</i>: extant populations from the Norwegian-Iceland Sea and Fram Strait

2013 ◽  
Vol 10 (9) ◽  
pp. 15077-15106 ◽  
Author(s):  
C. V. Dylmer ◽  
J. Giraudeau ◽  
V. Hanquiez ◽  
K. Husum
Keyword(s):  
Surface Water ◽  
Seasonal Change ◽  
North Atlantic ◽  
Emiliania Huxleyi ◽  
Seasonal Migration ◽  
The Arctic ◽  
Fram Strait ◽  
Production Area ◽  
Cell Densities ◽  
Coccolithus Pelagicus

Abstract. Extant coccolithophores and their relation to the governing oceanographic features in the northern North Atlantic were investigated along two zonal transects of surface water sampling, both conducted during summer 2011 and fall 2007. The northern transects crossed Fram Strait and its two opposing boundary currents (West Spitsbergen Current and East Greenland Current), while the southern transects sampled the Norwegian and Iceland Seas (passing the island Jan Mayen) from the Lofoten Islands to the continental margin off Eastern Greenland. The distribution of the dominant coccolithophore species Emiliania huxleyi and Coccolithus pelagicus is discussed in view of both the surface hydrology at the time of sampling and the structure of the surface mixed layer. Remote-sensing images as well as CTD and ARGO profiles are used to constrain the physico-chemical state of the surface water at the time of sampling. Both transects were characterized by strong seasonal differences in bulk coccolithophore standing stocks with maximum values of 53 × 103 cells L−1 for the northern transect and 72 × 103 cells L−1 for the southern transect in fall and summer, respectively. The highest recorded bulk cell densities are essentially explained by E. huxleyi. This species shows a zonal shift in peak abundance in the Norwegian-Iceland Seas from a summer maximum in the Lofoten gyre to peak cell densities around the island Jan Mayen in fall. Vertical mixing of Atlantic waters west of Lofoten Island, a phenomenom related to pervasive summer large scale atmospheric changes in the eastern Nordic Seas, on one hand, and strengthened influence of melt-water and related surface water stratification around the island Jan Mayen during fall, on the other hand, explains the observed seasonal migration of the E. huxleyi peak production area, as well as the seasonal change in dominating species within the Iceland Sea. In addition our datasets are indicative of a well-defined maximum boundary temperature of 6 °C for the production of C. pelagicus in the northern North Atlantic. The Fram Strait transects provides, to our knowledge, a first view of the zonal distribution of extant coccolithophores in this remote setting during summer and fall. Our datasets are indicative of a seasonal change in the species community from an E. huxleyi-dominated assemblage during summer to a C. pelagicus-rich population during fall. Here, higher irradiance and increased Atlantic water influence during summer favored the production of the opportunistic species E. huxleyi close to the Arctic Front, whereas the peak production area during fall, with high concentrations of C. pelagicus, lays in true Arctic/Polar waters.

scholarly journals Northward advection of Atlantic water in the eastern Nordic Seas over the last 3000 yr

2013 ◽  
Vol 9 (4) ◽  
pp. 1505-1518 ◽  
Author(s):  
C. V. Dylmer ◽  
J. Giraudeau ◽  
F. Eynaud ◽  
K. Husum ◽  
A. De Vernal
Keyword(s):  
Surface Water ◽  
North Atlantic ◽  
Barents Sea ◽  
Water Masses ◽  
Ice Age ◽  
The Arctic ◽  
Fram Strait ◽  
Nordic Seas ◽  
The North ◽  
The North Atlantic

Abstract. Three marine sediment cores distributed along the Norwegian (MD95-2011), Barents Sea (JM09-KA11-GC), and Svalbard (HH11-134-BC) continental margins have been investigated in order to reconstruct changes in the poleward flow of Atlantic waters (AW) and in the nature of upper surface water masses within the eastern Nordic Seas over the last 3000 yr. These reconstructions are based on a limited set of coccolith proxies: the abundance ratio between Emiliania huxleyi and Coccolithus pelagicus, an index of Atlantic vs. Polar/Arctic surface water masses; and Gephyrocapsa muellerae, a drifted coccolith species from the temperate North Atlantic, whose abundance changes are related to variations in the strength of the North Atlantic Current. The entire investigated area, from 66 to 77° N, was affected by an overall increase in AW flow from 3000 cal yr BP (before present) to the present. The long-term modulation of westerlies' strength and location, which are essentially driven by the dominant mode of the North Atlantic Oscillation (NAO), is thought to explain the observed dynamics of poleward AW flow. The same mechanism also reconciles the recorded opposite zonal shifts in the location of the Arctic front between the area off western Norway and the western Barents Sea–eastern Fram Strait region. The Little Ice Age (LIA) was governed by deteriorating conditions, with Arctic/Polar waters dominating in the surface off western Svalbard and western Barents Sea, possibly associated with both severe sea ice conditions and a strongly reduced AW strength. A sudden short pulse of resumed high WSC (West Spitsbergen Current) flow interrupted this cold spell in eastern Fram Strait from 330 to 410 cal yr BP. Our dataset not only confirms the high amplitude warming of surface waters at the turn of the 19th century off western Svalbard, it also shows that such a warming was primarily induced by an excess flow of AW which stands as unprecedented over the last 3000 yr.

scholarly journals Sea ice volume variability and water temperature in the Greenland Sea

2020 ◽  
Vol 14 (2) ◽  
pp. 477-495 ◽  
Author(s):  
Valeria Selyuzhenok ◽  
Igor Bashmachnikov ◽  
Robert Ricker ◽  
Anna Vesman ◽  
Leonid Bobylev
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Heat Content ◽  
The Arctic ◽  
Fram Strait ◽  
Greenland Sea ◽  
Nordic Seas ◽  
Ice Volume ◽  
Long Term Variations

Abstract. This study explores a link between the long-term variations in the integral sea ice volume (SIV) in the Greenland Sea and oceanic processes. Using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, 1979–2016), we show that the increasing sea ice volume flux through Fram Strait goes in parallel with a decrease in SIV in the Greenland Sea. The overall SIV loss in the Greenland Sea is 113 km3 per decade, while the total SIV import through Fram Strait increases by 115 km3 per decade. An analysis of the ocean temperature and the mixed-layer depth (MLD) over the climatic mean area of the winter marginal sea ice zone (MIZ) revealed a doubling of the amount of the upper-ocean heat content available for the sea ice melt from 1993 to 2016. This increase alone can explain the SIV loss in the Greenland Sea over the 24-year study period, even when accounting for the increasing SIV flux from the Arctic. The increase in the oceanic heat content is found to be linked to an increase in temperature of the Atlantic Water along the main currents of the Nordic Seas, following an increase in the oceanic heat flux from the subtropical North Atlantic. We argue that the predominantly positive winter North Atlantic Oscillation (NAO) index during the 4 most recent decades, together with an intensification of the deep convection in the Greenland Sea, is responsible for the intensification of the cyclonic circulation pattern in the Nordic Seas, which results in the observed long-term variations in the SIV.

scholarly journals Thermohaline Fingerprints of the Greenland-Scotland Ridge and Fram Strait Subsidence Histories

2020 ◽  
Author(s):  
Akil Hossain ◽  
Gregor Knorr ◽  
Gerrit Lohmann ◽  
Michael Stärz ◽  
Wilfried Jokat
Keyword(s):  
Southern Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Deep Water ◽  
The Arctic ◽  
Fram Strait ◽  
High Latitudes ◽  
Nordic Seas ◽  
Basin Scale ◽  
Salinity Increase

&lt;p&gt; &lt;span&gt;&lt;span&gt;Changes in ocean gateway configuration are known to induce basin-scale rearrangements in ocean characteristics throughout the Cenozoic. &lt;/span&gt;&lt;span&gt;However, there is large uncertainty in the relative timing of the &lt;/span&gt;&lt;span&gt;subsidence histories of ocean gateways in the northern high latitudes. By using a fully coupled General Circulation &lt;/span&gt;&lt;span&gt;Model we investigate the salinity and temperature changes in response to the subsidence of two key ocean gateways in the northern high latitudes during early to middle Miocene. &lt;/span&gt;&lt;span&gt;Deepening of the Greenland-Scotland Ridge &lt;/span&gt;&lt;span&gt;causes a salinity increase and warming in the Nordic Seas and the Arctic Ocean. &lt;/span&gt;&lt;span&gt;While warming this realm, deep water formation takes place at lower temperatures due to a shift of the convection sites to north off Iceland. &lt;/span&gt;&lt;span&gt;The associated deep ocean cooling and &lt;/span&gt;&lt;span&gt;upwelling of deep waters to the Southern Ocean surface causes a cooling in the southern high latitudes.&lt;/span&gt; &lt;span&gt;These characteristic impacts in response to the &lt;/span&gt;&lt;span&gt;Greenland-Scotland Ridge&lt;/span&gt;&lt;span&gt; deepening are independent of the &lt;/span&gt;&lt;span&gt;Fram Strait&lt;/span&gt;&lt;span&gt; state.&lt;/span&gt; &lt;span&gt;Subsidence of the Fram Strait for a deep Greenland-Scotland Ridge causes &lt;/span&gt;&lt;span&gt;less pronounced warming and salinity increase&lt;/span&gt;&lt;span&gt; in &lt;/span&gt;&lt;span&gt;the &lt;/span&gt;&lt;span&gt;Nordic Seas. &lt;/span&gt;&lt;span&gt;A stronger salinity increase is detected in the Arctic while temperatures remain unaltered, which further increases the density of the North Atlantic Deep Water. This causes an enhanced contribution of North Atlantic Deep Water &lt;/span&gt;&lt;span&gt;to the abyssal ocean and on the expense of the colder southern source water component. These relative changes largely counteract each other and cause little &lt;/span&gt;&lt;span&gt;warming in the upwelling regions of the Southern Ocean.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;

scholarly journals Simulated Arctic Ocean Freshwater Budgets in the Twentieth and Twenty-First Centuries

2006 ◽  
Vol 19 (23) ◽  
pp. 6221-6242 ◽  
Author(s):  
Marika M. Holland ◽  
Joel Finnis ◽  
Mark C. Serreze
Keyword(s):  
Arctic Ocean ◽  
North Atlantic ◽  
Climate Model ◽  
The Arctic ◽  
Fram Strait ◽  
Climate System Model ◽  
Ice Melt ◽  
East Greenland Current ◽  
Freshwater Fluxes ◽  
Gin Seas

Abstract The Arctic Ocean freshwater budgets in climate model integrations of the twentieth and twenty-first century are examined. An ensemble of six members of the Community Climate System Model version 3 (CCSM3) is used for the analysis, allowing the anthropogenically forced trends over the integration length to be assessed. Mechanisms driving trends in the budgets are diagnosed, and the implications of changes in the Arctic–North Atlantic exchange on the Labrador Sea and Greenland–Iceland–Norwegian (GIN) Seas properties are discussed. Over the twentieth and the twenty-first centuries, the Arctic freshens as a result of increased river runoff, net precipitation, and decreased ice growth. For many of the budget terms, the maximum 50-yr trends in the time series occur from approximately 1975 to 2025, suggesting that we are currently in the midst of large Arctic change. The total freshwater exchange between the Arctic and North Atlantic increases over the twentieth and twenty-first centuries with decreases in ice export more than compensated for by an increase in the liquid freshwater export. Changes in both the liquid and solid (ice) Fram Strait freshwater fluxes are transported southward by the East Greenland Current and partially removed from the GIN Seas. Nevertheless, reductions in GIN sea ice melt do result from the reduced Fram Strait transport and account for the largest term in the changing ocean surface freshwater fluxes in this region. This counteracts the increased ocean stability due to the warming climate and helps to maintain GIN sea deep-water formation.

scholarly journals Satellite-derived sea ice export and its impact on Arctic ice mass balance

2018 ◽  
Vol 12 (9) ◽  
pp. 3017-3032 ◽  
Author(s):  
Robert Ricker ◽  
Fanny Girard-Ardhuin ◽  
Thomas Krumpen ◽  
Camille Lique
Keyword(s):  
Sea Ice ◽  
Mass Balance ◽  
North Atlantic ◽  
Large Scale ◽  
The Arctic ◽  
Fram Strait ◽  
Ice Volume ◽  
Ice Drift ◽  
Ice Mass Balance ◽  
Arctic Ice

Abstract. Sea ice volume export through the Fram Strait represents an important freshwater input to the North Atlantic, which could in turn modulate the intensity of the thermohaline circulation. It also contributes significantly to variations in Arctic ice mass balance. We present the first estimates of winter sea ice volume export through the Fram Strait using CryoSat-2 sea ice thickness retrievals and three different ice drift products for the years 2010 to 2017. The monthly export varies between −21 and −540 km3. We find that ice drift variability is the main driver of annual and interannual ice volume export variability and that the interannual variations in the ice drift are driven by large-scale variability in the atmospheric circulation captured by the Arctic Oscillation and North Atlantic Oscillation indices. On shorter timescale, however, the seasonal cycle is also driven by the mean thickness of exported sea ice, typically peaking in March. Considering Arctic winter multi-year ice volume changes, 54  % of their variability can be explained by the variations in ice volume export through the Fram Strait.

scholarly journals Biogeochemical implications of comparative growth rates of <i>Emiliania huxleyi</i> and <i>Coccolithus</i> species

2014 ◽  
Vol 11 (7) ◽  
pp. 10513-10536
Author(s):  
C. J. Daniels ◽  
R. M. Sheward ◽  
A. J. Poulton
Keyword(s):  
Relative Abundance ◽  
North Atlantic ◽  
Growth Rates ◽  
Emiliania Huxleyi ◽  
Light Conditions ◽  
Comparative Physiology ◽  
Temperature Range ◽  
The North ◽  
Field Samples ◽  
Coccolithus Pelagicus

Abstract. Coccolithophores are a diverse and biogeochemically important group of phytoplankton in terms of the production and export of calcite, yet the comparative physiology and ecology of species other than the ubiquitous Emiliania huxleyi is poorly understood. Despite assumptions that Emiliania huxleyi is a fast growing species, we found it had comparable growth rates (0.16–0.85 d−1) with strains of Coccolithus pelagicus and Coccolithus braarudii when grown under identical temperature and light conditions. A recently isolated Arctic strain of C. pelagicus (RCC4092) exhibited only a 12% slower growth rate, on average, than a recently isolated Arctic strain of E. huxleyi (RCC3533), over a temperature range of 6–12 °C. Established temperate strains of E. huxleyi and C. braarudii (RCC1228 and RCC1198) exhibited a slightly larger difference in growth rates, with E. huxleyi growing 28% faster on average than C. braarudii over a temperature range of 12–19 °C. Coupled with the 30–80 times higher cellular calcite content of C. pelagicus and C. braarudii compared to E. huxleyi, this suggests that Coccolithus species could be major calcite producers in mixed populations. The relative abundance of coccolithophore species is key for determining which species will dominate calcite production in mixed communities growing at similar rates. Field samples from the North Atlantic show that C. pelagicus is in a high enough relative abundance in 69% of samples collected in the spring and summer of 2010 to be a larger source of calcite production than E. huxleyi.

scholarly journals Microbial metagenome-assembled genomes of the Fram Strait from short and long read sequencing platforms

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11721
Author(s):  
Taylor Priest ◽  
Luis H. Orellana ◽  
Bruno Huettel ◽  
Bernhard M. Fuchs ◽  
Rudolf Amann
Keyword(s):  
North Atlantic ◽  
The Arctic ◽  
Fram Strait ◽  
Water Column Stability ◽  
Exchange Processes ◽  
Sea Ice Decline ◽  
Long Read ◽  
Ecological Patterns ◽  
Sequencing Platforms ◽  
Impacts Of Climate Change

The impacts of climate change on the Arctic Ocean are manifesting throughout the ecosystem at an unprecedented rate. Of global importance are the impacts on heat and freshwater exchange between the Arctic and North Atlantic Oceans. An expanding Atlantic influence in the Arctic has accelerated sea-ice decline, weakened water column stability and supported the northward shift of temperate species. The only deep-water gateway connecting the Arctic and North Atlantic and thus, fundamental for these exchange processes is the Fram Strait. Previous research in this region is extensive, however, data on the ecology of microbial communities is limited, reflecting the wider bias towards temperate and tropical latitudes. Therefore, we present 14 metagenomes, 11 short-read from Illumina and three long-read from PacBio Sequel II, of the 0.2–3 µm fraction to help alleviate such biases and support future analyses on changing ecological patterns. Additionally, we provide 136 species-representative, manually refined metagenome-assembled genomes which can be used for comparative genomics analyses and addressing questions regarding functionality or distribution of taxa.

Sign in / Sign up

Export Citation Format

Share Document