scholarly journals Persistent shift of Calanus spp. in the southwestern Norwegian Sea since 2003, linked to ocean climate

2015 ◽  
Vol 73 (5) ◽  
pp. 1319-1329 ◽  
Author(s):  
Inga Kristiansen ◽  
Eilif Gaard ◽  
Hjálmar Hátún ◽  
Sigrún Jónasdóttir ◽  
A. Sofia A. Ferreira
Keyword(s):  
Phytoplankton Bloom ◽  
Dominant Role ◽  
Atlantic Water ◽  
Reproductive Period ◽  
Life Cycles ◽  
Water Masses ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Arctic Water ◽  
Norwegian Sea

Abstract The southwestern Norwegian Sea is characterized by an inflow of warm and saline Atlantic water from the southwest and cold and less saline East Icelandic Water (EIW), of Arctic origin, from the northwest. These two water masses meet and form the Iceland-Faroe Front (IFF). In this region, the copepod Calanus finmarchicus plays a key role in the pelagic ecosystem. Time-series of C. finmarchicus and Calanus hyperboreus in May and September, extending back to the early 1990s, were studied in relation to phytoplankton bloom dynamics and hydrography. The main reproductive period of C. finmarchicus started consistently earlier south of the IFF, resulting in different life cycles and stage compositions in the two water masses. In 2003, a sudden shift occurred north of the IFF, resulting in a similar phenology pattern to south of the IFF. Before this, only one generation of C. finmarchicus was produced in the Arctic water, but the earlier reproduction enabled the species to produce two generations after 2003. Simultaneously, C. hyperboreus, an expatriate in the EIW, largely disappeared. Food availability is unlikely the reason for the phenological differences observed across the front, as the typical pattern of the phytoplankton spring bloom showed an earlier onset north of the IFF. Temperature and salinity peaked at record high values in 2003 and 2004, and therefore possible links to oceanography are discussed. The dominant role of Calanus spp. and the potential linkages to water mass exchanges may herald strong effects on the ecosystem and pelagic fish in this subpolar Atlantic region under expected climate change.

scholarly journals Enhancement of the North Atlantic CO<sub>2</sub> sink by Arctic Waters

2021 ◽  
Vol 18 (5) ◽  
pp. 1689-1701
Author(s):  
Jon Olafsson ◽  
Solveig R. Olafsdottir ◽  
Taro Takahashi ◽  
Magnus Danielsen ◽  
Thorarinn S. Arnarson
Keyword(s):  
North Atlantic ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
Water Masses ◽  
The Arctic ◽  
Arctic Water ◽  
The North ◽  
The North Atlantic ◽  
Co2 Sink ◽  
The One

Abstract. The North Atlantic north of 50∘ N is one of the most intense ocean sink areas for atmospheric CO2 considering the flux per unit area, 0.27 Pg-C yr−1, equivalent to −2.5 mol C m−2 yr−1. The northwest Atlantic Ocean is a region with high anthropogenic carbon inventories. This is on account of processes which sustain CO2 air–sea fluxes, in particular strong seasonal winds, ocean heat loss, deep convective mixing, and CO2 drawdown by primary production. The region is in the northern limb of the global thermohaline circulation, a path for the long-term deep-sea sequestration of carbon dioxide. The surface water masses in the North Atlantic are of contrasting origins and character, with the northward-flowing North Atlantic Drift, a Gulf Stream offspring, on the one hand and on the other hand the cold southward-moving low-salinity Polar and Arctic waters with signatures from Arctic freshwater sources. We have studied by observation the CO2 air–sea flux of the relevant water masses in the vicinity of Iceland in all seasons and in different years. Here we show that the highest ocean CO2 influx is to the Arctic and Polar waters, respectively, -3.8±0.4 and -4.4±0.3 mol C m−2 yr−1. These waters are CO2 undersaturated in all seasons. The Atlantic Water is a weak or neutral sink, near CO2 saturation, after poleward drift from subtropical latitudes. These characteristics of the three water masses are confirmed by data from observations covering 30 years. We relate the Polar Water and Arctic Water persistent undersaturation and CO2 influx to the excess alkalinity derived from Arctic sources. Carbonate chemistry equilibrium calculations clearly indicate that the excess alkalinity may support at least 0.058 Pg-C yr−1, a significant portion of the North Atlantic CO2 sink. The Arctic contribution to the North Atlantic CO2 sink which we reveal was previously unrecognized. However, we point out that there are gaps and conflicts in the knowledge about the Arctic alkalinity and carbonate budgets and that future trends in the North Atlantic CO2 sink are connected to developments in the rapidly warming and changing Arctic. The results we present need to be taken into consideration for the following question: will the North Atlantic continue to absorb CO2 in the future as it has in the past?

scholarly journals The Barents Sea frontal zones and water masses variability (1980–2011)

Ocean Science ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 169-184 ◽  
Author(s):  
L. Oziel ◽  
J. Sirven ◽  
J.-C. Gascard
Keyword(s):  
Interannual Variability ◽  
Barents Sea ◽  
Sea Water ◽  
Atlantic Water ◽  
Polar Front ◽  
Water Masses ◽  
The Arctic ◽  
Arctic Water ◽  
The Barents Sea ◽  
Frontal Zones

Abstract. The polar front separates the warm and saline Atlantic Water entering the southern Barents Sea from the cold and fresh Arctic Water located in the north. These water masses can mix together (mainly in the center of the Barents Sea), be cooled by the atmosphere and receive salt because of brine release; these processes generate dense water in winter, which then cascades into the Arctic Ocean to form the Arctic Intermediate Water. To study the interannual variability and evolution of the frontal zones and the corresponding variations of the water masses, we have merged data from the International Council for the Exploration of the Sea and the Arctic and Antarctic Research Institute and have built a new database, which covers the 1980–2011 period. The summer data were interpolated on a regular grid. A probability density function is used to show that the polar front splits into two branches east of 32° E where the topographic constraint weakens. Two fronts can then be identified: the Northern Front is associated with strong salinity gradients and the Southern Front with temperature gradients. Both fronts enclose the denser Barents Sea Water. The interannual variability of the water masses is apparent in the observed data and is linked to that of the ice cover. The frontal zones variability is found by using data from a general circulation model. The link with the atmospheric variability, represented here by the Arctic Oscillation, is not clear. However, model results suggest that such a link could be validated if winter data were taken into account. A strong trend appears: the Atlantic Water (Arctic Water) occupies a larger (smaller) volume of the Barents Sea. This trend amplifies during the last decade and the model study suggests that this could be accompanied by a northwards displacement of the Southern Front in the eastern part of the Barents Sea. The results are less clear for the Northern Front. The observations show that the volume of the Barents Sea Water remains nearly unchanged, which suggests a northwards shift of the Northern Front to compensate for the northward shift of the Southern Front. Lastly, we noticed that the seasonal variability of the position of the front is small.

scholarly journals Enhancement of the North Atlantic CO<sub>2</sub> sink by Arctic Waters

2020 ◽  
Author(s):  
Jon Olafsson ◽  
Solveig R. Olafsdottir ◽  
Taro Takahashi ◽  
Magnus Danielsen ◽  
Thorarinn S. Arnarson
Keyword(s):  
North Atlantic ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
Water Masses ◽  
The Arctic ◽  
Arctic Water ◽  
The North ◽  
The North Atlantic ◽  
Co2 Sink ◽  
The One

Abstract. The North Atlantic north of 50° N is one of the most intense ocean sink areas for atmospheric CO2 considering the flux per unit area, 0.27 Pg-C yr−1, equivalent to −2.5 mol C m−2 yr−1. The Northwest Atlantic Ocean is a region with high anthropogenic carbon inventories. This is on account of processes which sustain CO2 air-sea fluxes, in particular strong seasonal winds, ocean heat loss, deep convective mixing and CO2 drawdown by primary production. The region is in the northern limb of the Global Thermohaline Circulation, a path for the long term deep sea sequestration of carbon dioxide. The surface water masses in the North Atlantic are of contrasting origins and character, on the one hand the northward flowing North Atlantic Drift, a Gulf Stream offspring, on the other hand southward moving cold low salinity Polar and Arctic Waters with signatures from Arctic freshwater sources. We have studied by observations, the CO2 air-sea flux of the relevant water masses in the vicinity of Iceland in all seasons and in different years. Here we show that the highest ocean CO2 influx is to the Arctic and Polar waters, respectively, −3.8 mol C m−2 yr−1 and −4.4 mol C m−2 yr−1. These waters are CO2 undersaturated in all seasons. The Atlantic Water is a weak or neutral sink, near CO2 saturation, after poleward drift from subtropical latitudes. These characteristics of the three water masses are confirmed by data from observations covering 30 years. We relate the Polar and Arctic Water persistent undersaturation and CO2 influx to the excess alkalinity derived from Arctic sources, particularly the Arctic rivers. Carbonate chemistry equilibrium calculations indicate clearly that the excess alkalinity may support a significant portion of the North Atlantic CO2 sink. The Arctic contribution to the North Atlantic CO2 sink which we reveal is previously unrecognized. However, we point out that there are gaps and conflicts in the knowledge about the Arctic alkalinity budget and that future trends in the North Atlantic CO2 sink are connected to developments in the rapidly warming Arctic. The results we present need to be taken into consideration for the question: Will the North Atlantic continue to absorb CO2 in the future as it has in the past?

scholarly journals Contribution of Calanus species to the mesozooplankton biomass in the Barents Sea

2017 ◽  
Vol 75 (7) ◽  
pp. 2342-2354 ◽  
Author(s):  
Johanna Myrseth Aarflot ◽  
Hein Rune Skjoldal ◽  
Padmini Dalpadado ◽  
Mette Skern-Mauritzen
Keyword(s):  
Barents Sea ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Arctic Water ◽  
Mesozooplankton Biomass ◽  
The Barents Sea ◽  
Main Driver ◽  
Calanus Species

Abstract Copepods from the genus Calanus are crucial prey for fish, seabirds and mammals in the Nordic and Barents Sea ecosystems. The objective of this study is to determine the contribution of Calanus species to the mesozooplankton biomass in the Barents Sea. We analyse an extensive dataset of Calanus finmarchicus, Calanus glacialis, and Calanus hyperboreus, collected at various research surveys over a 30-year period. Our results show that the Calanus species are a main driver of variation in the mesozooplankton biomass in the Barents Sea, and constitutes around 80% of the total. The proportion of Calanus decreases at low zooplankton biomass, possibly due to a combination of advective processes (low C. finmarchicus in winter) and size selective foraging. Though the Calanus species co-occur in most regions, C. glacialis dominates in the Arctic water masses, while C. finmarchicus dominates in Atlantic waters. The larger C. hyperboreus has considerably lower biomass in the Barents Sea than the other Calanus species. Stages CIV and CV have the largest contribution to Calanus species biomass, whereas stages CI-CIII have an overall low impact on the biomass. In the western area of the Barents Sea, we observe indications of an ongoing borealization of the zooplankton community, with a decreasing proportion of the Arctic C. glacialis over the past 20 years. Atlantic C. finmarchicus have increased during the same period.

scholarly journals Declining silicate concentrations in the Norwegian and Barents Seas

2012 ◽  
Vol 69 (2) ◽  
pp. 208-212 ◽  
Author(s):  
Francisco Rey
Keyword(s):  
North Atlantic ◽  
Relative Proportion ◽  
Atlantic Water ◽  
Water Masses ◽  
Source Water ◽  
Marine Science ◽  
Norwegian Sea

Abstract Rey, F. 2012. Declining silicate concentrations in the Norwegian and Barents Seas. – ICES Journal of Marine Science, 69: 208–212. Since 1990, a decline in silicate concentrations together with increasing salinities has been observed in the Atlantic water of the Norwegian and Barents Seas. This decline in silicate has been found to be related to the relative proportion in which eastern and western source water masses from the northeastern North Atlantic enter the Norwegian Sea.

scholarly journals Influence of Atlantic inflow on the freshwater content in the upper layer of the Arctic basin

2019 ◽  
Vol 65 (4) ◽  
pp. 363-388
Author(s):  
G. V. Alekseev ◽  
A. V. Pnyushkov ◽  
A. V. Smirnov ◽  
A. E. Vyazilova ◽  
N. I. Glok
Keyword(s):  
Fresh Water ◽  
Large Scale ◽  
Barents Sea ◽  
Lower Boundary ◽  
Arctic Basin ◽  
Water Layer ◽  
Atlantic Water ◽  
Water Masses ◽  
The Arctic ◽  
The North

Inter-decadal changes in the water layer of Atlantic origin and freshwater content (FWC) in the upper 100 m layer were traced jointly to assess the influence of inflows from the Atlantic on FWC changes based on oceanographic observations in the Arctic Basin for the 1960s – 2010s. For this assessment, we used oceanographic data collected at the Arctic and Antarctic Research Institute (AARI) and the International Arctic Research Center (IARC). The AARI data for the decades of 1960s – 1990s were obtained mainly at the North Pole drifting ice camps, in high-latitude aerial surveys in the 1970s, as well as in ship-based expeditions in the 1990s. The IARC database contains oceanographic measurements acquired using modern CTD (Conductivity – Temperature – Depth) systems starting from the 2000s. For the reconstruction of decadal fields of the depths of the upper and lower 0 °С isotherms and FWC in the 0–100 m layer in the periods with a relatively small number of observations (1970s – 1990s), we used a climatic regression method based on the conservativeness of the large-scale structure of water masses in the Arctic Basin. Decadal fields with higher data coverage were built using the DIVAnd algorithm. Both methods showed almost identical results when compared.  The results demonstrated that the upper boundary of the Atlantic water (AW) layer, identified with the depth of zero isotherm, raised everywhere by several tens of meters in 1990s – 2010s, when compared to its position before the start of warming in the 1970s. The lower boundary of the AW layer, also determined by the depth of zero isotherm, became deeper. Such displacements of the layer boundaries indicate an increase in the volume of water in the Arctic Basin coming not only through the Fram Strait, but also through the Barents Sea. As a result, the balance of water masses was disturbed and its restoration had to occur due to the reduction of the volume of the upper most dynamic freshened layer. Accordingly, the content of fresh water in this layer should decrease. Our results confirmed that FWC in the 0–100 m layer has decreased to 2 m in the Eurasian part of the Arctic Basin to the west of 180° E in the 1990s. In contrast, the FWC to the east of 180° E and closer to the shores of Alaska and the Canadian archipelago has increased. These opposite tendencies have been intensified in the 2000s and the 2010s. A spatial correlation between distributions of the FWC and the positions of the upper AW boundary over different decades confirms a close relationship between both distributions. The influence of fresh water inflow is manifested as an increase in water storage in the Canadian Basin and the Beaufort Gyre in the 1990s – 2010s. The response of water temperature changes from the tropical Atlantic to the Arctic Basin was traced, suggesting not only the influence of SST at low latitudes on changes in FWC, but indicating the distant tropical impact on Arctic processes. 

The Annual Oceanographic Cycle at Igloolik in the Canadian Arctic. 1. The Zooplankton and Physical and Chemical Observations

1959 ◽  
Vol 16 (4) ◽  
pp. 453-501 ◽  
Author(s):  
E. H. Grainger
Keyword(s):  
Surface Area ◽  
Canadian Arctic ◽  
Abundant Species ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Late Winter ◽  
Arctic Water ◽  
Oithona Similis ◽  
Single Station ◽  
Materials Used

Materials used were collected September 1955 to September 1956 near Igloolik, northwest Foxe Basin, in the Canadian arctic. A single station, about one mile from shore and 52 m deep, was occupied 27 times during the year. It is in a region of net flow of arctic water from Fury and Hecla Strait, whose strong current probably brings ever-changing hydrographic conditions and plankton populations to the station area. Sea ice formed in early November, and had thickened to about 152 cm by early May. Melting then began and continued until the station was free of fast ice soon after mid-July. Water temperatures varied only 3.55 °C at all depths during the year, and only 0.07° from November until May. The coldest record was −1.75° at 50 m in April and May, the warmest 1.80° at the surface in early September. Salinities varied from a maximum of 32.59‰ in early May to less than 1.68‰ at the surface in mid-July. A thin layer of brackish water, probably not exceeding 2 m in depth, was developed at the surface during the ice-melting period from late June until early August. Dissolved oxygen content varied from 9.52 ml/1 in early July to 4.08 ml/l in early September. The maximum saturation recorded was 110.3% at 10 m on July 15. Dissolved inorganic phosphate rose from near zero in February to a maximum of 1.5 μg-at/l in mid-June, then declined until autumn.Zooplankton volume (from the coarse net) was greatest in late September (4.85 ml per 50-m haul), least in mid-April (0.15 ml). Among identifiable material, copepods were volumetically the largest group. Twenty-eight species were identified, the most numerous forms being copepods (Pseudocalanus minutus, Calanus finmarchicus, C. hyperboreus, Oithona similis), chaetognaths (Sagitta elegans), cirriped larvae, medusae (Halitholus cirratus) and larvaceans (Fritillaria borealis). Several of the more abundant species provide life-history information. All the plankton species had previously been collected in the arctic, and all are circumpolar (one possible exception).Propagation times of primarily herbivorous plankters coincide with the abundance of their phytoplankton food, and the numerical cycle of these individuals during the year shows a restricted period of maximum numbers during the time of reproduction (summer) followed by gradual decline until late winter. In contrast, the primarily carnivorous plankters show relatively slight numerical variation throughout the year, and no concentrated period of reproduction. These species reproduce at various times of the year, many of them during winter. A rough estimate of the Igloolik yearly mean standing crop of zooplankton (without correction for straining efficiency of the No. 6xxx net) is 0.10 ml/m3 or 5.2 ml/m2 of surface area; the maximum observed was 0.50 ml/m3. Another arctic coastal locality, in Greenland, had similar figures; coastal boreal stations have mean crops 4 to 8 times as great (volume basis) or 2 to 9 times as great (surface area basis).

scholarly journals Different methanotrophic potentials in stratified polar fjord waters (Storfjorden, Spitsbergen) identified by using a combination of methane oxidation techniques

2013 ◽  
Vol 10 (4) ◽  
pp. 6461-6491 ◽  
Author(s):  
S. Mau ◽  
J. Blees ◽  
E. Helmke ◽  
H. Niemann ◽  
E. Damm
Keyword(s):  
Water Column ◽  
Methane Oxidation ◽  
Deep Water ◽  
Oxidation Potential ◽  
Water Masses ◽  
Spatiotemporal Variability ◽  
The Arctic ◽  
Type I ◽  
Turnover Rates ◽  
Arctic Water

Abstract. The bacterially mediated aerobic methane oxidation (MOx) is a key mechanism in controlling methane (CH4) emissions from the world's oceans to the atmosphere. In this study, we investigated MOx in the Arctic fjord Storfjorden (Spitsbergen) by applying a combination of radio-tracer based incubation assays (3H-CH4 and 14H-CH4), stable C-CH4 isotope measurements, and molecular tools (16S rRNA DGGE-fingerprinting, pmoA- and mxaF gene analyses). Strofjorden is stratified in the summertime with melt water (MW) in the upper 60 m of the water column, Arctic water (ArW) between 60–100 m and brine-enriched shelf water (BSW) down to 140 m. CH4 concentrations were supersaturated with respect to the atmospheric equilibrium (∼3 nM) throughout the water column, increasing from ∼20 nM at the surface to a maximum of 72 nM at 60 m and decreasing below. MOx rate measurements at near in situ CH4 concentrations (here measured with 3H-CH4 raising the ambient CH4 pool by <2 nM) showed a similar trend: low rates at the sea surface increasing to a maximum of ∼2.3 nM d−1 at 60 m followed by a decrease in the deeper ArW/BSW. In contrast, rate measurements with 14H-CH4 at elevated CH4 concentrations (incubations were spiked with ∼450 nM of 14H-CH4, providing an estimate of the CH4 oxidation potential) showed comparably low turnover rates (<1 nMd−1) at 60 m, but peaked in ArW/BSW at ∼100 m water depth, concomitant with increasing 14C-values in the residual CH4 pool. Our results indicate that the MOx community in the surface MW is adapted to relatively low CH4 concentrations. In contrast, the activity of the deep water MOx community is relatively low at the ambient, summertime CH4 concentrations but has the potential to increase rapidly in response to CH4 availability. A similar distinction between surface and deep water MOx is also suggested by our molecular analyses. Although, we found pmoA and maxF gene sequences throughout the water column attesting the ubiquitous presence of MOx communities in Storfjorden, deep water amplicons of pmoA and maxF were unusually long. Also a DGGE band related to the known Type I MOx Mehtylosphera was observed in deep BWS, but absent in surface MW. Apparently, different MOx communities have developed in the stratified water masses in Storfjorden, which is possibly related to the spatiotemporal variability in CH4 supply to the distinct water masses.

scholarly journals HEAVY METALS IN ZOOPLANKTON ORGANISMS OF THE BARENTS SEA

2019 ◽  
Vol 47 (4) ◽  
pp. 62-75
Author(s):  
L. L. Demina ◽  
A. S. Solomatina ◽  
G. A. Abyzova
Keyword(s):  
Heavy Metals ◽  
Barents Sea ◽  
Water Mass ◽  
Atlantic Water ◽  
Polar Front ◽  
The Arctic ◽  
Phytoplankton Production ◽  
Arctic Water ◽  
The Barents Sea ◽  
Geochemical Parameters

Zooplankton plays a Central role in the transfer of matter and energy from primary producers to high trophic organisms, and zooplankton serves as an essential component of sedimentary material that supplies organic matter to the bottom of marine basins. The paper presents new data on the distribution of a number of heavy metals (Cd, Co, Cr, Cu, Mo, Ni, Pb) and As in the Calanus zooplankton collected in July–August 2017 in the North-Eastern, Eastern and Central parts of the Barents Sea. It is shown that the spatial distribution of metals in zooplankton organisms is influenced by both biotic ecosystem factors associated with bioproductivity and hydrological and geochemical parameters of the habitat (North Polar Front). In the zooplankton of the Arctic water mass to the South-East of Franz Josef Land, there was an increased content of essential heavy metals Cu, Zn and Cr in comparison with the coastal and Atlantic water masses. Zooplankton from the Central part of the sea (Atlantic water mass), where phytoplankton production is reduced, is characterized by the lowest concentrations of most elements (Ni, Cu, Zn, As and Pb). The highest concentrations were found for both essential heavy metals (Zn and Cu) and toxic metalloid As, which may indicate non-selective bioaccumulation of trace elements by copepods.

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