Artículos de revistas: "Atlantification"

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Polyakov, Igor V., Randi B. Ingvaldsen, Andrey V. Pnyushkov, Uma S. Bhatt, Jennifer A. Francis, Markus Janout, Ronald Kwok y Øystein Skagseth. "Fluctuating Atlantic inflows modulate Arctic atlantification". Science 381, n.º 6661 (septiembre de 2023): 972–79. http://dx.doi.org/10.1126/science.adh5158.

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Enhanced warm, salty subarctic inflows drive high-latitude atlantification, which weakens oceanic stratification, amplifies heat fluxes, and reduces sea ice. In this work, we show that the atmospheric Arctic Dipole (AD) associated with anticyclonic winds over North America and cyclonic winds over Eurasia modulates inflows from the North Atlantic across the Nordic Seas. The alternating AD phases create a “switchgear mechanism.” From 2007 to 2021, this switchgear mechanism weakened northward inflows and enhanced sea-ice export across Fram Strait and increased inflows throughout the Barents Sea. By favoring stronger Arctic Ocean circulation, transferring freshwater into the Amerasian Basin, boosting stratification, and lowering oceanic heat fluxes there after 2007, AD+ contributed to slowing sea-ice loss. A transition to an AD− phase may accelerate the Arctic sea-ice decline, which would further change the Arctic climate system.

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Kujawa, Agnieszka, Magdalena Łącka, Natalia Szymańska, Joanna Pawłowska, Maciej M. Telesiński y Marek Zajączkowski. "Could Norwegian fjords serve as an analogue for the future of the Svalbard fjords? State and fate of high latitude fjords in the face of progressive “atlantification”". Polar Biology 44, n.º 12 (18 de octubre de 2021): 2217–33. http://dx.doi.org/10.1007/s00300-021-02951-z.

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AbstractBenthic foraminifera are one of the most widely and abundantly distributed organisms in the fjords of Svalbard and Norway. Due to their short life span and quick reactivity to environmental changes they can be used as indicators of the “atlantification” process. Here, we compare the benthic foraminifera assemblages along the latitudinal gradient, from the fjords of northern Svalbard to southern Norway to assess whether the “atlantification” process may homogenise the foraminiferal assemblages in terms of their abundance and species composition. Furthermore, the previously published data on benthic foraminiferal faunas was updated to identify changes in distribution that have occurred over the last few decades. For this purpose, fjord mouths in western and northern Svalbard (Isfjorden, Wijdefjorden and Rijpfjorden) and northern and southern Norway (Balsfjorden, Raunefjorden and Hjeltefjorden) were resampled. The analysis revealed similarities between the Svalbard and Norwegian foraminiferal assemblages of up to 30%; however, there were essential differences in terms of abundance and biodiversity. These results suggest that Svalbard fjords will remain distinct in the future, even under conditions of further warming or “atlantification”. Svalbard fjords may be dominated by Atlantic Water- preferring species, whereas, in Norwegian fjords, pressure from human activity will probably be the main driver of environmental changes, leading to changes in the foraminiferal assemblages with the increasing dominance of opportunistic, hypoxia-tolerant species.

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Ingvaldsen, Randi B., Karen M. Assmann, Raul Primicerio, Maria Fossheim, Igor V. Polyakov y Andrey V. Dolgov. "Physical manifestations and ecological implications of Arctic Atlantification". Nature Reviews Earth & Environment 2, n.º 12 (16 de noviembre de 2021): 874–89. http://dx.doi.org/10.1038/s43017-021-00228-x.

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4

Blum, Hester. "Atlantification: Facing the Atlantic from the Arctic – a provocation". Atlantic Studies 21, n.º 1 (2 de enero de 2024): 192–94. http://dx.doi.org/10.1080/14788810.2023.2287277.

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5

Aksenov, P. V. y V. V. Ivanov. "“Atlantification” as a Possible Cause for Reducing of the Sea-Ice Cover in the Nansen Basin in winter". Arctic and Antarctic Research 64, n.º 1 (30 de marzo de 2018): 42–54. http://dx.doi.org/10.30758/0555-2648-2018-64-1-42-54.

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The paper presents arguments in favor of an explanation of the reduction of the ice-covered area in the Nansen basin of the Arctic Ocean (AO) in winter by the so-called “atlantification “ — the strengthening of the influence of waters of Atlantic origin on the hydrological regime of the Arctic Ocean. We hypothesize that the main agent of “atlantification” in theWesternNansenBasinis winter thermal convection, which delivers heat from the deep to the upper mixed layer, thus melting sea ice and warming the near-surface air. To check up this hypothesis we used ocean reanalysis MERCATOR data for time interval 2007–2017. The quantitative criterion of thermal convection, based on the type of vertical thermohaline structure in the upper ocean layer, was applied to access the change of convection depth between climatic values in 1950–1990 and the present time. The main conclusion of the paper can be summarized as the following. Due to a gradual reduction of sea ice in the 1990s, the vertical stratification of waters in theWesternNansenBasinhas changed. As a result, the potential for penetration of vertical thermal convection into the warm and saline Atlantic layer and the consumption of heat and salt content of this layer for warming and salinification of the overlying waters increased, thus leading to additional loss of sea ice in winter.

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Weydmann-Zwolicka, Agata, Paula Prątnicka, Magdalena Łącka, Sanna Majaneva, Finlo Cottier y Jørgen Berge. "Zooplankton and sediment fluxes in two contrasting fjords reveal Atlantification of the Arctic". Science of The Total Environment 773 (junio de 2021): 145599. http://dx.doi.org/10.1016/j.scitotenv.2021.145599.

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Belter, H. Jakob, Thomas Krumpen, Luisa von Albedyll, Tatiana A. Alekseeva, Gerit Birnbaum, Sergei V. Frolov, Stefan Hendricks et al. "Interannual variability in Transpolar Drift summer sea ice thickness and potential impact of Atlantification". Cryosphere 15, n.º 6 (15 de junio de 2021): 2575–91. http://dx.doi.org/10.5194/tc-15-2575-2021.

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Abstract. Changes in Arctic sea ice thickness are the result of complex interactions of the dynamic and variable ice cover with atmosphere and ocean. Most of the sea ice exiting the Arctic Ocean does so through Fram Strait, which is why long-term measurements of ice thickness at the end of the Transpolar Drift provide insight into the integrated signals of thermodynamic and dynamic influences along the pathways of Arctic sea ice. We present an updated summer (July–August) time series of extensive ice thickness surveys carried out at the end of the Transpolar Drift between 2001 and 2020. Overall, we see a more than 20 % thinning of modal ice thickness since 2001. A comparison of this time series with first preliminary results from the international Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) shows that the modal summer thickness of the MOSAiC floe and its wider vicinity are consistent with measurements from previous years at the end of the Transpolar Drift. By combining this unique time series with the Lagrangian sea ice tracking tool, ICETrack, and a simple thermodynamic sea ice growth model, we link the observed interannual ice thickness variability north of Fram Strait to increased drift speeds along the Transpolar Drift and the consequential variations in sea ice age. We also show that the increased influence of upward-directed ocean heat flux in the eastern marginal ice zones, termed Atlantification, is not only responsible for sea ice thinning in and around the Laptev Sea but also that the induced thickness anomalies persist beyond the Russian shelves and are potentially still measurable at the end of the Transpolar Drift after more than a year. With a tendency towards an even faster Transpolar Drift, winter sea ice growth will have less time to compensate for the impact processes, such as Atlantification, have on sea ice thickness in the eastern marginal ice zone, which will increasingly be felt in other parts of the sea-ice-covered Arctic.

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8

Ahme, Antonia, Anabel Von Jackowski, Rebecca A. McPherson, Klara K. E. Wolf, Mario Hoppmann, Stefan Neuhaus y Uwe John. "Winners and Losers of Atlantification: The Degree of Ocean Warming Affects the Structure of Arctic Microbial Communities". Genes 14, n.º 3 (1 de marzo de 2023): 623. http://dx.doi.org/10.3390/genes14030623.

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Arctic microbial communities (i.e., protists and bacteria) are increasingly subjected to an intrusion of new species via Atlantification and an uncertain degree of ocean warming. As species differ in adaptive traits, these oceanic conditions may lead to compositional changes with functional implications for the ecosystem. In June 2021, we incubated water from the western Fram Strait at three temperatures (2 °C, 6 °C, and 9 °C), mimicking the current and potential future properties of the Arctic Ocean. Our results show that increasing the temperature to 6 °C only minorly affects the community, while an increase to 9 °C significantly lowers the diversity and shifts the composition. A higher relative abundance of large hetero- and mixotrophic protists was observed at 2 °C and 6 °C compared to a higher abundance of intermediate-sized temperate diatoms at 9 °C. The compositional differences at 9 °C led to a higher chlorophyll a:POC ratio, but the C:N ratio remained similar. Our results contradict the common assumption that smaller organisms and heterotrophs are favored under warming and strongly indicate a thermal limit between 6 °C and 9 °C for many Arctic species. Consequently, the magnitude of temperature increase is a crucial factor for microbial community reorganization and the ensuing ecological consequences in the future Arctic Ocean.

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Freer, Jennifer J., Malin Daase y Geraint A. Tarling. "Modelling the biogeographic boundary shift of Calanus finmarchicus reveals drivers of Arctic Atlantification by subarctic zooplankton". Global Change Biology 28, n.º 2 (27 de octubre de 2021): 429–40. http://dx.doi.org/10.1111/gcb.15937.

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10

Mańko, Maciej K., Marta Gluchowska y Agata Weydmann-Zwolicka. "Footprints of Atlantification in the vertical distribution and diversity of gelatinous zooplankton in the Fram Strait (Arctic Ocean)". Progress in Oceanography 189 (noviembre de 2020): 102414. http://dx.doi.org/10.1016/j.pocean.2020.102414.

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11

Barton, Benjamin I., Yueng-Djern Lenn y Camille Lique. "Observed Atlantification of the Barents Sea Causes the Polar Front to Limit the Expansion of Winter Sea Ice". Journal of Physical Oceanography 48, n.º 8 (agosto de 2018): 1849–66. http://dx.doi.org/10.1175/jpo-d-18-0003.1.

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AbstractBarents Sea Water (BSW) is formed from Atlantic Water that is cooled through atmospheric heat loss and freshened through seasonal sea ice melt. In the eastern Barents Sea, the BSW and fresher, colder Arctic Water meet at the surface along the Polar Front (PF). Despite its importance in setting the northern limit of BSW ventilation, the PF has been poorly documented, mostly eluding detection by observational surveys that avoid seasonal sea ice. In this study, satellite sea surface temperature (SST) observations are used in addition to a temperature and salinity climatology to examine the location and structure of the PF and characterize its variability over the period 1985–2016. It is shown that the PF is independent of the position of the sea ice edge and is a shelf slope current constrained by potential vorticity. The main driver of interannual variability in SST is the variability of the Atlantic Water temperature, which has significantly increased since 2005. The SST gradient associated with the PF has also increased after 2005, preventing sea ice from extending south of the front during winter in recent years. The disappearance of fresh, seasonal sea ice melt south of the PF has led to a significant increase in BSW salinity and density. As BSW forms the majority of Arctic Intermediate Water, changes to BSW properties may have far-reaching impacts for Arctic Ocean circulation and climate.

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12

Orlov, Alexei M., Svetlana Yu Orlova, Maxim O. Rybakov, Olga R. Emelianova y Elena V. Vedishcheva. "First Record of the Northern Wolffish Anarhichas denticulatus Krøyer, 1845 (Anarhichadidae: Zoarcoidei: Perciformes) in the Siberian Arctic: Further Evidence of Atlantification?" Climate 11, n.º 5 (6 de mayo de 2023): 101. http://dx.doi.org/10.3390/cli11050101.

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A single specimen of the northern wolffish Anarhichas denticulatus Krøyer, 1845, 393 mm in length, was documented for the first time in the Siberian Arctic (Laptev Sea, Russia). Species identification was confirmed by an integrative taxonomic approach that included examination of external morphology and DNA barcoding using the COI mtDNA gene. This species is widely distributed in the North Atlantic, but records in the Arctic Ocean are limited to the Canadian and US coasts. This record might represent a significant range extension of about 7500 km for the species and may be associated with the eastward transport of a pelagic juvenile specimen from the Northeastern Atlantic to the Laptev Sea by the North Atlantic current, consistent with the hypothesis of Atlantification of the Arctic Ocean. X-ray images of the Laptev Sea specimen and photographs showing ontogenetic variations of species’ coloration are provided for reference. The Laptev Sea specimen had a more elongated shape, longer preorbital distance, and longer pectoral, dorsal, and anal fins, as well as a larger eye and wider caudal fin compared to North Atlantic samples. The size differences are likely associated with conditions experienced as a juvenile during the pelagic stage of the lifecycle.

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13

Górska, Barbara, Sławomira Gromisz, Joanna Legeżyńska, Thomas Soltwedel y Maria Włodarska-Kowalczuk. "Macrobenthic diversity response to the atlantification of the Arctic Ocean (Fram Strait, 79°N) – A taxonomic and functional trait approach". Ecological Indicators 144 (noviembre de 2022): 109464. http://dx.doi.org/10.1016/j.ecolind.2022.109464.

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14

Watelet, Sylvain, Øystein Skagseth, Vidar S. Lien, Helge Sagen, Øivind Østensen, Viktor Ivshin y Jean-Marie Beckers. "A volumetric census of the Barents Sea in a changing climate". Earth System Science Data 12, n.º 4 (12 de octubre de 2020): 2447–57. http://dx.doi.org/10.5194/essd-12-2447-2020.

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Abstract. The Barents Sea, located between the Norwegian Sea and the Arctic Ocean, is one of the main pathways of the Atlantic Meridional Overturning Circulation. Changes in the water mass transformations in the Barents Sea potentially affect the thermohaline circulation through the alteration of the dense water formation process. In order to investigate such changes, we present here a seasonal atlas of the Barents Sea including both temperature and salinity for the period 1965–2016. The atlas is built as a compilation of datasets from the World Ocean Database, the Polar Branch of the Russian Federal Research Institute of Fisheries and Oceanography and the Norwegian Polar Institute using the Data-Interpolating Variational Analysis (DIVA) tool. DIVA allows for a minimization of the expected error with respect to the true field. The atlas is used to provide a volumetric analysis of water mass characteristics and an estimation of the ocean heat and freshwater contents. The results show a recent “Atlantification” of the Barents Sea, that is a general increase in both temperature and salinity, while its density remains stable. The atlas is made freely accessible as user-friendly NetCDF files to encourage further research in the Barents Sea physics (https://doi.org/10.21335/NMDC-2058021735, Watelet et al., 2020).

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Mioduchowska, Monika, Joanna Pawłowska, Karol Mazanowski y Agata Weydmann-Zwolicka. "Contrasting Marine Microbial Communities of the Fram Strait with the First Confirmed Record of Cyanobacteria Prochlorococcus marinus in the Arctic Region". Biology 12, n.º 9 (17 de septiembre de 2023): 1246. http://dx.doi.org/10.3390/biology12091246.

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The seawater microbiome is crucial in marine ecosystems because of its role in food chains and biogeochemical cycles; thus, we studied the composition of the pelagic marine microbiome collected in the upper 50 m on the opposite sides of Fram Strait: Spitsbergen and Greenland shelves. We found out that it differed significantly, with salinity being the main environmental variable responsible for these differences. The Spitsbergen shelf was dominated by Atlantic Waters, with a rather homogenous water column in terms of salinity and temperature down to 300 m; hence, the marine microbial community was also homogenous at all sampled depths (0, 25, 50 m). On the contrary, stations on the Greenland shelf were exposed to different water masses of both Arctic and Atlantic origin, which resulted in a more diverse microbial community there. Unexpectedly, for the very first time, we identified cyanobacterium Prochlorococcus marinus in Arctic waters (Spitsbergen shelf, 75–77° N). Till now, the distribution of this cyanobacteria in oceans has been described only between 40° N and 40° S. Considering the accelerated rate of climate warming in the Arctic, our results indicated that the seawater microbiome can be viewed as an amplifier of global change and that the Atlantification is in progress.

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Dvoretsky, Vladimir G., Marina P. Venger, Anastasya V. Vashchenko, Veronika V. Vodopianova, Ivan A. Pastukhov y Tatyana M. Maksimovskaya. "Marine Plankton during the Polar Night: Environmental Predictors of Spatial Variability". Biology 12, n.º 3 (25 de febrero de 2023): 368. http://dx.doi.org/10.3390/biology12030368.

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We studied the spatial patterns of the planktonic ecosystems at two Arctic sites strongly affected by Atlantic Inflow (FS, the Fram Strait; and BS, the Barents Sea). A high degree of similarity in the bacterial abundance (mean: 3.1 × 105 cells mL−1 in FS vs. 3.5 × 105 cells mL−1 in BS) was found, while other plankton characteristics were different. Bacterial biomass reached a maximum in BS (3.2–7.9 mg C m−3), while viral abundances tended to be higher in FS (2.0–5.7 × 106 particles mL−1). Larger bacterial cells were found in BS, suggesting the presence of different bacterial populations at both locations. The virus-to-bacteria ratio was significantly higher in FS than in BS (13.5 vs. 4.7). Chlorophyll a concentration was extremely low (<0.25 mg m−3). The highest zooplankton abundance was in the surface layer (919 individuals m−3 in FS vs. 602 ind. m−3 in BS). Zooplankton biomass strongly varied (1–39 mg C m−3), with the maximum in BS. High proportions of boreal taxa in the total zooplankton abundance indicate the Atlantification of pelagic ecosystems in the Arctic. Plankton indicators are correlated with temperature, salinity, and sampling depth. Strong intercorrelations were found between major plankton groups, suggesting tight links in the studied plankton ecosystems.

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Giorli, Giacomo, Aniello Russo y Sandro Carniel. "Noise levels in a changing Arctic Ocean and its implications for security". Journal of the Acoustical Society of America 154, n.º 4_supplement (1 de octubre de 2023): A133. http://dx.doi.org/10.1121/10.0023028.

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Arctic Ocean is undergoing an “Atlantification” of its oceanographic properties. Sea ice retreat and reduction of sea ice age will affect its underwater soundscape, with anthropogenic noise expected to increase due to the exploitation of new maritime routes. The CMRE’s Environmental and Operational Effectiveness Programme conducted a study of the new Arctic oceanographic conditions and ambient noise by deploying in 2021 and in 2022 different moorings equipped with passive acoustic recorders and oceanographic sensors. Data did not show a clear relation between sea-ice concentration and noise levels in the marginal ice zone. However, noise levels indicate that the possible presence of transmissions ducts might increase high frequency noise in the subsurface area. Seasonality and variations in the overall soundscapes were also evident by the presence of sounds from biological sources. In 2023, with the support of the NATO Office of the Chief Scientist, CMRE started a long-term scientific endeavor to study how climate change might affect the Alliance’s security in the maritime domain. A significant research effort is focused on the Arctic, and in June–July 2023 CMRE deployed three deep moorings for monitoring the acoustic-oceanographic conditions in the long term. [Work supported by the NATO Allied Command Transformation.]

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18

Årthun, M., T. Eldevik, L. H. Smedsrud, Ø. Skagseth y R. B. Ingvaldsen. "Quantifying the Influence of Atlantic Heat on Barents Sea Ice Variability and Retreat*". Journal of Climate 25, n.º 13 (1 de julio de 2012): 4736–43. http://dx.doi.org/10.1175/jcli-d-11-00466.1.

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Abstract The recent Arctic winter sea ice retreat is most pronounced in the Barents Sea. Using available observations of the Atlantic inflow to the Barents Sea and results from a regional ice–ocean model the authors assess and quantify the role of inflowing heat anomalies on sea ice variability. The interannual variability and longer-term decrease in sea ice area reflect the variability of the Atlantic inflow, both in observations and model simulations. During the last decade (1998–2008) the reduction in annual (July–June) sea ice area was 218 × 103 km2, or close to 50%. This reduction has occurred concurrent with an increase in observed Atlantic heat transport due to both strengthening and warming of the inflow. Modeled interannual variations in sea ice area between 1948 and 2007 are associated with anomalous heat transport (r = −0.63) with a 70 × 103 km2 decrease per 10 TW input of heat. Based on the simulated ocean heat budget it is found that the heat transport into the western Barents Sea sets the boundary of the ice-free Atlantic domain and, hence, the sea ice extent. The regional heat content and heat loss to the atmosphere scale with the area of open ocean as a consequence. Recent sea ice loss is thus largely caused by an increasing “Atlantification” of the Barents Sea.

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Pnyushkov, Andrey V., Genrikh V. Alekseev y Alexander V. Smirnov. "On the Interplay between Freshwater Content and Hydrographic Conditions in the Arctic Ocean in the 1990s–2010s". Journal of Marine Science and Engineering 10, n.º 3 (10 de marzo de 2022): 401. http://dx.doi.org/10.3390/jmse10030401.

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We investigated liquid freshwater content (FWC) in the upper 100 m layer of the Arctic Ocean using oceanographic observations covering the period from 1990 through 2018. Our analysis revealed two opposite tendencies in freshwater balance—the freshening in the Canada Basin at the mean rate of 2.04 ± 0.64 m/decade and the salinization of the eastern Eurasian Basin (EB) at the rate of 0.96 ± 0.86 m/decade. In line with this, we found that the Arctic Ocean gained an additional 19,000 ± 1000 km3 of freshwater over the 1990–2018 period. FWC changes in the EB since 1990 demonstrate an intermittent pattern with the most rapid decrease (from ~5.5 to 3.8 m) having occurred between 2000 and 2005. The 1990–2018 FWC changes in the upper ocean were concurrent with prominent changes of the thermohaline properties of the intermediate Atlantic Water (AW)—the main source of salt and heat for the Arctic Basin. In the eastern EB, we found a 50 m rise of the upper AW boundary accompanied by a ~0.5 °C increase in the AW core temperature. The close relationship (R > 0.7 ± 0.2) between available potential energy in the layer above the AW and FWC in the eastern EB suggests a positive feedback mechanism that links the amount of freshwater with the intensity of vertical heat and salt exchange in the halocline and upper AW layers. Together with other mechanisms of Atlantification, this feedback creates a complex picture of interactions behind the observed changes in the hydrological and ice regimes of the Eurasian sector of the Arctic Ocean.

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Kudryavtseva, Е. A., M. D. Kravchishina, L. A. Pautova, I. I. Rusanov, V. A. Silkin, D. I. Glukhovets, N. N. Torgunova et al. "PRIMARY PRODUCERS SIZE STRUCTURE IN THE MARGINAL ICE ZONE OF EUROPEAN ARCTIC IN SUMMER". Доклады Российской академии наук. Науки о Земле 508, n.º 1 (1 de enero de 2023): 108–14. http://dx.doi.org/10.31857/s2686739722601788.

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Primary production (PP) and chlorophyll “a” concentration (chl “a”) estimates in the Eurasian Arctic are discussed, where the continued climatic warming with increased “Atlantification” advance the sea ice losses. The maximum integrated PP and the total chl “a” content observed in the marginal ice zone (MIZ) of the Barents Sea with weakened stratification of the water column and reached 1109 mgC m–2 day–1 and 118 mg m–2. Nearby the ice edge in the Nansen Basin, the main part of PP formed in the upper mixed layer and did not exceed 469 mgC m–2 day–1, the chl “a” content of 56 mg m–2. In the early and late phytoplankton bloom in MIZ, the typical leading role of picophytoplankton in carbon fixation revealed. Large centric diatoms, microphytoplankton, dominated at the peak bloom stage in 2020 with the dense marine ice cover of the Nansen Basin. A similar phenomenon was previously observed only in the Arctic shelf seas and was not recorded in the high-latitude basins of the Arctic Ocean. With the sparse ice cover of the Nansen Basin in 2021, the main primary producers at the peak bloom were pico- and nanophytoplankton. The low variability of assimilation numbers at all bloom stages (1.7 ± 0.3 mgC mg chl “a”–1 h–1) indicates the acclimatization of phytoplankton to changing environment. The ecological flexibility of the primary production are link of the MLZ ecosystems in the studied seas of the European Arctic during the period of climate change is confirmed.

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Shabanov, Pavel, Alexander Osadchiev, Natalya Shabanova y Stanislav Ogorodov. "Decline in Ice Coverage and Ice-Free Period Extension in the Kara and Laptev Seas during 1979–2022". Remote Sensing 16, n.º 11 (24 de mayo de 2024): 1875. http://dx.doi.org/10.3390/rs16111875.

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The duration of ice-free periods in different parts of the Arctic Ocean plays a great role in processes in the climate system and defines the most comfortable sea ice conditions for economic activity. Based on satellite-derived sea ice concentration data acquired by passive microwave instruments, we identified the spatial distribution of the dates of sea ice retreat (DOR), dates of sea ice advance (DOA), and the resulting ice-free period duration (IFP) between these days for the Kara and Laptev seas during 1979–2022. The monthly decline in sea ice extent was detected from June to October in both seas, i.e., during the whole ice-free period. The annual mean sea ice extent during 2011–2021 decreased by 19.0% and 12.8% relative to the long-term average during 1981–2010 in the Kara and Laptev seas, respectively. The statistically significant (95% confidence level) positive IFP trends were detected for the majority of areas of the Kara and Laptev seas. Averaged IFP trends were estimated equal to +20.2 day/decade and +16.2 day/decade, respectively. The observed DOR tendency to earlier sea ice melting plays a greater role in the total IFP extension, as compared to later sea ice formation related to the DOA tendency. We reveal that regions of inflow of warm Atlantic waters to the Kara Sea demonstrate the largest long-term trends in DOA, DOR, and IFP associated with the decrease in ice coverage, that highlights the process of atlantification. Also, the Great Siberian Polynya in the Laptev Sea is the area of the largest long-term decreasing trend in DOR.

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Oziel, L., J. Sirven y J. C. Gascard. "The Barents Sea polar front and water masses variability (1980–2011)". Ocean Science Discussions 12, n.º 2 (10 de marzo de 2015): 449–92. http://dx.doi.org/10.5194/osd-12-449-2015.

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Abstract. The polar front separates the warm and saline Atlantic Waters encountered in the western part of the Barents Sea from the cold and fresh Arctic Waters situated in the northern part. These water masses can mix together, mainly in the eastern part of the Barents Sea, generating dense waters in winter which can cascade into the Arctic Ocean to form the Artic Intermediate Waters. To study the interannual variability and evolution of these water masses and the fronts, 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 period 1980–2011. The summer data is interpolated on a regular grid and a "Probability Density Function" method 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 defined: the "Northern Polar Front" is associated with strong salinity gradients and the "Southern Polar Front" with temperature gradients. They enclose the dense 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. In contrast, the link with the Arctic Oscillation is not clear. However, results from a general circulation model suggest that such a link could be found if winter data were taken into account. A strong trend, which amplifies during the last decade, is also found: the Atlantic Water occupies a larger volume of the Barents Sea. This "Atlantification" could be accompanied by a northwards displacement of the southern polar front in the eastern part of the Barents Sea (which is suggested by a model based study) and a decrease of the volume occupied by the Arctic Waters.

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Henley, Sian F., Marie Porter, Laura Hobbs, Judith Braun, Robin Guillaume-Castel, Emily J. Venables, Estelle Dumont y Finlo Cottier. "Nitrate supply and uptake in the Atlantic Arctic sea ice zone: seasonal cycle, mechanisms and drivers". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, n.º 2181 (31 de agosto de 2020): 20190361. http://dx.doi.org/10.1098/rsta.2019.0361.

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Nutrient supply to the surface ocean is a key factor regulating primary production in the Arctic Ocean under current conditions and with ongoing warming and sea ice losses. Here we present seasonal nitrate concentration and hydrographic data from two oceanographic moorings on the northern Barents shelf between autumn 2017 and summer 2018. The eastern mooring was sea ice-covered to varying degrees during autumn, winter and spring, and was characterized by more Arctic-like oceanographic conditions, while the western mooring was ice-free year-round and showed a greater influence of Atlantic water masses. The seasonal cycle in nitrate dynamics was similar under ice-influenced and ice-free conditions, with biological nitrate uptake beginning near-synchronously in early May, but important differences between the moorings were observed. Nitrate supply to the surface ocean preceding and during the period of rapid drawdown was greater at the ice-free more Atlantic-like western mooring, and nitrate drawdown occurred more slowly over a longer period of time. This suggests that with ongoing sea ice losses and Atlantification, the expected shift from more Arctic-like ice-influenced conditions to more Atlantic-like ice-free conditions is likely to increase nutrient availability and the duration of seasonal drawdown in this Arctic shelf region. The extent to which this increased nutrient availability and longer drawdown periods will lead to increases in total nitrate uptake, and support the projected increases in primary production, will depend on changes in upper ocean stratification and their effect on light availability to phytoplankton as changes in climate and the physical environment proceed. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

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24

Panicker, Dency V., Bhasha Vachharajani, Rohit Srivastava y Sandip R. Oza. "Analysis of sea ice concentration and thickness over Barents Sea using standard logistic curve model". Journal of Geomatics 17, n.º 1 (28 de abril de 2023): 68–84. http://dx.doi.org/10.58825/jog.2023.17.1.74.

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As marginal, the Barents Sea plays a major role in the process of Atlantification, and large seasonal variability in sea ice is observed over the region. Current sea ice concentration and thickness obtained from satellite help one understand the variation in sea ice is seasonal. During summer, the concentration and thickness of sea ice are seen to fall, and during winters, it is seen to rise. In order to understand the difference in these variabilities and to analyse the future state of sea ice, a standard logistic curve model is considered. The standard logistic curve model is applied to sea ice parameters during summer and winter to quantify the sea ice growth and decay processes over the Barents Sea.The model yields predicted values based on the adjustment parameter (b) used.Results show that the predicted sea ice concentration performs well with the satellite sea ice concentration values. The model is run on the timeframe grouped into two, with each set having an average of ten years from 2000-2020. For the decay process, the fitted sea ice concentration decay curves derived from the standard logistic curve model are in good agreement with the observed data for the two timelines, with r2 = 0.88 and 0.87, respectively. Similarly, for the growth process, the relevant fitted decay curves derived from the standard logistic curve model are also in good agreement with the observed data during the above different time periods withr2= 0.80 and 0.78, respectively. Further, the model is implied to sea ice thickness, and the result obtained by the logistic curve model is found to be consistent with the satellite sea ice thickness with r2 = 0.75 for the years 2011–2020. Particularly, both the rapid sea ice increase pattern during the growth process and the remarkable decrease pattern during the decay process are successfully characterized by the corresponding fitted curves. The introduction of calculated adjustment parameters into the model helps in accurately determining the sea ice variables, which brings us closer to conservation tools that mitigate therisks associated with rapid sea ice loss.

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25

Sumkina, A. A., K. K. Kivva, V. V. Ivanov y A. V. Smirnov. "Seasonal ice removal in the Barents Sea and its dependence on heat advection by Atlantic waters". Fundamental and Applied Hydrophysics 15, n.º 1 (1 de abril de 2022): 82–97. http://dx.doi.org/10.59887/fpg/1krp-xbuk-6gpz.

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The Barents Sea is one of the key areas in the Arctic for monitoring of climate change. Although the Barents Sea is one of the Arctic seas, it is never completely covered with ice. One of the parameters characterizing the change in the ice regime is the date of ice retreat (DOR). The study is based on ice concentration data from the NOAA / NSIDC Climate Data Record (CDR) from 1979 to 2019 and the GLORYS12V1 ocean reanalysis data from 1993 to 2019. The analysis of the spatial and temporal variability of DOR for the Barents Sea using the HDBSCAN cluster analysis method made it possible to identify areas (clusters) with the synchronous dynamics of DOR. A number of the identified areas are located on the path of the Atlantic waters (AW) in the Barents Sea, which made it possible to relate the revealed temporal variability of the DOR to the variability of the AW transport across the western boundary of the sea. Over the entire Barents Sea, after 2003, there has been a steady trend in the timing of seasonal ice removal to earlier ones. At the same time, each of the six regions identified has its own dynamics and rate of changes in DOR. A noticeable effect of the advective heat flux across the western boundary of the Barents Sea on the DOR was revealed for areas in the central and eastern parts of the sea. At the same time, for different regions, the maximum correlation coefficient is observed at different time lags (from 0 to 6 months). The value of the time lag indirectly indicates the time the thermal signal travels the distance from the western boundary of the sea to the corresponding region. The continuing trend towards an increase in the duration of the ice–free season in the Barents Sea is one of the manifestations of the growing “Atlantification” of the East Atlantic sector of the Arctic Ocean which opens up new prospects for socio–economic activity in this Arctic region.

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26

Serykh, I. V. y A. V. Tolstikov. "Climate change in the western part of the Russian Arctic in 1980–2021. Part 1. Air temperature, precipitation, wind". Arctic and Antarctic Research 68, n.º 3 (27 de septiembre de 2022): 258–77. http://dx.doi.org/10.30758/0555-2648-2022-68-3-258-277.

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The warming of the Arctic climate is confirmed by changes in the main hydrometeorological values of the atmosphere and ocean over a long period of time, and it is most pronounced in the recent decades. Based on monthly average data from the reanalysis of NASA MERRA-2 satellite measurements, we studied climate changes in air temperature, precipitation, and wind speed in the region of the western part of the Russian Arctic (60°–75° N, 30°–85° E) over 1980–2021. The transition between 2000 and 2001 was chosen as the time boundary between the periods, based on the application of the model of stepwise transitions from one quasi-stationary regime to another. Using this method, 2001 was found to be the smallest step year in the western Russian Arctic region. Significant changes in the parameters studied between the periods 1980–2000 and 2001–2021 are shown. Moreover, the strongest increase in temperature was observed for the months of November and April, which indicates a shift in the boundaries of the seasons — a later start and an early end of winter. It was found that in the period 2001–2021 the temperature increased most rapidly in the water areas of the Barents and Kara seas, and this growth occurred with acceleration. Negative temperature changes were found in the winter season in the areas where large rivers flow into the Barents and Kara Seas. It is hypothesized that this is due to the detected increase in the amount of precipitation in the catchment area of these rivers in 2001–2021 compared to 1980–2000. It is shown that the detected increase in the amount of precipitation is associated with a significant change in the atmospheric circulation in the region under study. In the summer season and September the western wind intensified in the region under study. During the winter season 2001–2021 in the Barents and Kara Seas the south wind increased compared to 1980–2000. Thus, significant changes in the climate of the western part of the Russian Arctic occurred during the time period considered. Westerly transport from the North Atlantic has intensified, precipitation has increased, and there has been an accelerated rise in temperature. All this contributed to the “atlantification” of the climate of the western part of the Russian Arctic.

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27

Santos-Garcia, Marta, Raja S. Ganeshram, Robyn E. Tuerena, Margot C. F. Debyser, Katrine Husum, Philipp Assmy y Haakon Hop. "Nitrate isotope investigations reveal future impacts of climate change on nitrogen inputs and cycling in Arctic fjords: Kongsfjorden and Rijpfjorden (Svalbard)". Biogeosciences 19, n.º 24 (22 de diciembre de 2022): 5973–6002. http://dx.doi.org/10.5194/bg-19-5973-2022.

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Abstract. Ongoing climate change in the Arctic has caused tidewater glaciers to retreat while increasing the discharge of freshwater and terrestrial material into fjords. This can affect both nutrient inputs and cycling within the fjord systems. In particular, tidewater glaciers and the presence of associated subglacial meltwater plumes can have a large impact on fjord circulation and biogeochemistry. In this study, we assess the influence of tidewater glaciers on nitrogen inputs and cycling in two fjords in Svalbard during the summer using stable isotopic analyses of dissolved nitrate (δ15N and δ18O) in combination with nutrient and hydrographic data. Kongsfjorden receives inputs from tidewater glaciers, whereas Rijpfjorden mainly receives surface inputs from land-terminating glaciers. Results showed that both fjords are enriched in nutrients from terrestrial inputs. Nutrient ratios indicate excess Si and P relative to N. In both fjords, terrestrial nitrate from snowpack and glacier melting are identified as the dominant sources based on high δ18O-NO3- and low δ15N-NO3- of dissolved nitrate. In Kongsfjorden, mixed-layer nitrate is completely consumed within the fjord system, which we attribute to vigorous circulation at the glacial front influenced by the subglacial plume and longer residence time in the fjord. This is in contrast to Rijpfjorden where nutrients are only partially consumed perhaps due to surface river discharge and light limitation. In Kongsfjorden, we estimate terrestrial and marine N contributions to the nitrate pool from nitrogen isotopic values (δ15N-NO3-), and this suggests that nearly half the nitrate in the subglacial plume (50 ± 3 %) and the water column (44 ± 3 %) originates from terrestrial sources. We show that terrestrial N contributes significantly to the regenerated N pool (63 %–88 %) within this fjord suggesting its importance in sustaining productivity here. Given this importance of terrestrial nutrient sources within the fjords, increase in these inputs due to climate change can enhance the fjord nutrient inventory, productivity and nutrient export offshore. Specifically, increasing Atlantification and warmer Atlantic Water will encourage tidewater glacier retreat and in turn increase surface discharge. In fjords akin to Rijpfjorden this is expected to foster more light limitation and less dynamic circulation, ultimately aiding the export of nutrients offshore contributing to coastal productivity. Climate change scenarios postulated for fjords such as Kongsfjorden include more terrestrial N-fuelled productivity and N cycling within the fjord, less vigorous circulation due to the retreat of tidewater glaciers, and the expansion of oxygen-depleted deep waters isolated by the sill.

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28

Noh, Kyung‐Min, Ji‐Hoon Oh, Hyung‐Gyu Lim, Hajoon Song y Jong‐Seong Kug. "Role of Atlantification in Enhanced Primary Productivity in the Barents Sea". Earth's Future 12, n.º 1 (enero de 2024). http://dx.doi.org/10.1029/2023ef003709.

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AbstractRecent changes in the Arctic sea‐ice are strongly influenced by the recent increase in heat transport from vigorous Atlantic inflows, so‐called Atlantification. This Atlantification can induce physical and ecological changes near the Atlantic gateway. Here, we used the observational data sets and 26 Earth system models to estimate Atlantic water intrusion, and firstly suggest the impact of Atlantification on marine productivity in the Barents Sea in a warming climate, especially on boreal spring. In a warming climate, the heat transport across the Barents Sea Opening (BSO) is projected to be enhanced (45.5 ± 34.9 TW) by the end of the 21st century compared to the present climate. This poleward intrusion of the Atlantic water is likely to increase productivity with the largest increase in spring (70%). In a warming climate, the productivity is enhanced by Atlantification‐induced changes in physical states—ocean temperature, circulations, stratification, and sea‐ice. Based on inter‐model analyses, we estimated that the Atlantification can explain approximately 26% of the productivity changes in the Barents Sea. Thus, Atlantification is critical for future changes in biological productivity and physical states over the Arctic Ocean.

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29

Muilwijk, Morven, Aleksi Nummelin, Céline Heuzé, Igor V. Polyakov, Hannah Zanowski y Lars H. Smedsrud. "Divergence in Climate Model Projections of Future Arctic Atlantification". Journal of Climate, 30 de noviembre de 2022, 1–53. http://dx.doi.org/10.1175/jcli-d-22-0349.1.

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Abstract The Arctic Ocean is strongly stratified by salinity in the uppermost layers. This stratification is a key attribute of the region as it acts as an effective barrier for the vertical exchanges of Atlantic Water heat, nutrients, and CO2 between intermediate depths and the surface of the Eurasian and Amerasian basins (EB and AB). Observations show that from 1970 to 2017, the stratification in the AB has strengthened, whereas, in parts of the EB, the stratification has weakened. The strengthening in the AB is linked to freshening and deepening of the halocline. In the EB, the weakened stratification is associated with salinification and shoaling of the halocline (Atlantification). Simulations from a suite of CMIP6 models project that, under a strong greenhouse-gas forcing scenario (ssp585), the overall surface freshening and warming continue in both basins, but there is a divergence in hydrographic trends in certain regions. Within the AB, there is agreement among the models that the upper layers will become more stratified. However, within the EB, models diverge regarding future stratification. This is due to different balances between trends at the surface and trends at depth, related to Fram Strait fluxes. The divergence affects projections of the future state of Arctic sea ice, as models with the strongest Atlantification project the strongest decline in sea ice volume in the EB. From these simulations, one could conclude that Atlantificaton will not spread eastward into the AB; however, models must be improved to simulate changes in a more intricately stratified EB correctly.

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30

Asbjørnsen, Helene, Marius Årthun, Øystein Skagseth y Tor Eldevik. "Mechanisms Underlying Recent Arctic Atlantification". Geophysical Research Letters 47, n.º 15 (4 de agosto de 2020). http://dx.doi.org/10.1029/2020gl088036.

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31

Descamps, Sébastien, Katarzyna Wojczulanis-Jakubas, Dariusz Jakubas, Mikko Vihtakari, Harald Steen, Nina J. Karnovsky, Jorg Welcker et al. "Consequences of Atlantification on a Zooplanktivorous Arctic Seabird". Frontiers in Marine Science 9 (20 de junio de 2022). http://dx.doi.org/10.3389/fmars.2022.878746.

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Global warming, combined with an increasing influence of Atlantic Waters in the European Arctic, are causing a so-called Atlantification of the Arctic. This phenomenon is affecting the plankton biomass and communities with potential consequences for the upper trophic levels. Using long-term data (2005-2020) from a high Arctic zooplanktivorous seabird, the little auk (Alle alle), we tested the hypothesis that the Atlantification affects its diet, body condition and demography. We based our study on data collected in three fjords in West Spitsbergen, Svalbard, characterized by distinct oceanographic conditions. In all three fjords, we found a positive relationship between the inflow of Atlantic Waters and the proportion of Atlantic prey, notably of the copepod Calanus finmarchicus, in the little auk chick diet. A high proportion of Atlantic prey was negatively associated with adult body mass (though the effect size was small) and with chick survival (only in one fjord where chick survival until 21 days was available). We also found a negative and marginally significant effect of the average proportion of Atlantic prey in the chick diet on chick growth rate (data were available for one fjord only). Our results suggest that there are fitness costs for the little auk associated with the Atlantification of West Spitsbergen fjords. These costs seem especially pronounced during the late phase of the chick rearing period, when the energetic needs of the chicks are the highest. Consequently, even if little auks can partly adapt their foraging behaviour to changing environmental conditions, they are negatively affected by the ongoing changes in the Arctic marine ecosystems. These results stress the importance of long-term monitoring data in the Arctic to improve our understanding of the ongoing Atlantification and highlight the relevance of using seabirds as indicators of environmental change.

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32

Balazy, Kaja, Emilia Trudnowska, Katarzyna Wojczulanis-Jakubas, Dariusz Jakubas, Kim Præbel, Marvin Choquet, Melissa M. Brandner et al. "Molecular tools prove little auks from Svalbard are extremely selective for Calanus glacialis even when exposed to Atlantification". Scientific Reports 13, n.º 1 (22 de agosto de 2023). http://dx.doi.org/10.1038/s41598-023-40131-7.

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AbstractTwo Calanus species, C. glacialis and C. finmarchicus, due to different life strategies and environmental preferences act as an ecological indicators of Arctic Atlantification. Their high lipid content makes them important food source for higher trophic levels of Arctic ecosystems including the most abundant Northern Hemisphere's seabird, the little auk (Alle alle). Recent studies indicate a critical need for the use of molecular methods to reliably identify these two sympatric Calanus species. We performed genetic and morphology-based identification of 2600 Calanus individuals collected in little auks foraging grounds and diet in summer seasons 2019–2021 in regions of Svalbard with varying levels of Atlantification. Genetic identification proved that 40% of Calanus individuals were wrongly classified as C. finmarchicus according to morphology-based identification in both types of samples. The diet of little auks consisted almost entirely of C. glacialis even in more Atlantified regions. Due to the substantial bias in morphology-based identification, we expect that the scale of the northern expansion of boreal C. finmarchicus may have been largely overestimated and that higher costs for birds exposed to Atlantification could be mostly driven by a decrease in the size of C. glacialis rather than by shift from C. glacialis to C. finmarchicus.

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33

Liu, Yujun y Yijun He. "Cold season Arctic strong cyclones enhance Atlantification of the Arctic Ocean". Environmental Research Letters, 19 de octubre de 2023. http://dx.doi.org/10.1088/1748-9326/ad0518.

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Abstract In recent years, as the Arctic Ocean's warming trend has accelerated, there has been increasing attention on the process of Atlantification in the Arctic Ocean. This study focused on the Arctic Atlantic inflow zone (AAZ) as its research area. Multi-source reanalysis data and in-situ Argo float data were utilized to detect Arctic strong cyclones (ASCs) in the AAZ and analyze the resulting changes in the upper ocean. The findings reveal that during the cold season (October to March), influenced by ASCs' intensity, frequency, tracks, and the concurrent weakening of ocean stratification, these cyclones can disrupt the cold halocline layer (CHL) through mechanisms such as mixing and Ekman pumping. This process facilitates the transport of heat from the deep, warm and saline Atlantic Water within the ocean to the subsurface layers. Concurrently, ASCs during the cold season can enhance the process of Atlantification in the Arctic Ocean by intensifying the intrusion of the Barents Sea Branch. Additionally, the attenuation of oceanic stratification during ASCs is primarily driven by changes in salinity, particularly above the 100 m.

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34

Vihtakari, Mikko, Jorg Welcker, Børge Moe, Olivier Chastel, Sabrina Tartu, Haakon Hop, Claus Bech, Sébastien Descamps y Geir Wing Gabrielsen. "Black-legged kittiwakes as messengers of Atlantification in the Arctic". Scientific Reports 8, n.º 1 (19 de enero de 2018). http://dx.doi.org/10.1038/s41598-017-19118-8.

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35

Golikov, Alexey V., Lis L. Jørgensen, Rushan M. Sabirov, Denis V. Zakharov y Henk-Jan Hoving. "Long-term annual trawl data show shifts in cephalopod community in the western Barents sea during 18 years". Frontiers in Marine Science 11 (23 de mayo de 2024). http://dx.doi.org/10.3389/fmars.2024.1392585.

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Climate change is threatening marine ecosystems on a global scale but particularly so in the Arctic. As a result of warming, species are shifting their distributions, altering marine communities and predator-prey interactions. This is known as the Atlantification of the Arctic. Warming may favor short-lived, opportunistic species such as cephalopods, marine mollusks that previously have been hypothesized to be winners in an ocean of change. To detect temporal regional trends in biodiversity, long-term annual surveys in hotspots of climate change are an unparalleled source of data. Here, we use 18 years of annual bottom trawl data (2005–2022) to analyse cephalopods in the western Barents Sea. More specifically, our research goals are to assess temporal trends in cephalopod fauna composition, abundance and biomass, and to relate these trends to climate change in the western Barents Sea. Main changes in cephalopod diversity and distribution occurred in mid-2000s and early 2010s, which corresponds with a period of warming in the Arctic since the late 1990s/early 2000s. Repeated increased occurrence of the boreal-subtropical cephalopods was recorded from 2005–2013 to 2014–2022. Moreover, the abundance of cephalopods in the area (in general and for most taxa) increased from 2005–2013 to 2014–2022. These observations suggest that the cephalopod community of the Barents Sea is subjected to Atlantification since the 2005–2013 period. This corresponds with previously reported evidence of the Atlantification in fishes and benthic invertebrates in the Barents Sea and benthic invertebrates. ‘Typical’ Arctic cephalopod species such as Bathypolypus spp., Gonatus fabricii and Rossia spp., however, are still much more abundant in the western Barents Sea compared to the deep-sea and the boreal-subtropical species. We also found indirect indications for body-size reduction in Bathypolypus spp. from 2005–2013 to 2014–2022. Overall, the temporal trends in the Barents Sea cephalopod fauna provide evidence for changing marine communities in the Arctic.

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36

Tesi, Tommaso, Francesco Muschitiello, Gesine Mollenhauer, Stefano Miserocchi, Leonardo Langone, Chiara Ceccarelli, Giuliana Panieri et al. "Rapid Atlantification along the Fram Strait at the beginning of the 20th century". Science Advances 7, n.º 48 (26 de noviembre de 2021). http://dx.doi.org/10.1126/sciadv.abj2946.

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37

Wold, Anette, Haakon Hop, Camilla Svensen, Janne E. Søreide, Karen M. Assmann, Mateusz Ormanczyk y Slawomir Kwasniewski. "Atlantification influences zooplankton communities seasonally in the northern Barents Sea and Arctic Ocean". Progress in Oceanography, septiembre de 2023, 103133. http://dx.doi.org/10.1016/j.pocean.2023.103133.

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38

Wang, Qiang y Sergey Danilov. "A Synthesis of the Upper Arctic Ocean Circulation During 2000–2019: Understanding the Roles of Wind Forcing and Sea Ice Decline". Frontiers in Marine Science 9 (18 de mayo de 2022). http://dx.doi.org/10.3389/fmars.2022.863204.

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Major changes have occurred in the Arctic Ocean during 2000–2019, including the unprecedented spin-up of the Beaufort Gyre and the emergence of Arctic Atlantification in the eastern Eurasian Basin. We explored the main drivers for these changes by synthesizing numerical simulations and observations in this paper. The Arctic atmospheric circulation was unusual in some years in this period, with strongly negative wind curl over the Canada Basin. However, the wind-driven spin-up of the Beaufort Gyre would have been much weaker had it not been for Arctic sea ice decline. The sea ice decline not only fed the ocean with meltwater, but also made other freshwater components more available to the Beaufort Gyre through mediating the ocean surface stress. This dynamical effect of shifting surface freshwater from the Eurasian Basin towards the Amerasian Basin also resulted in the Arctic Atlantification in the eastern Eurasian Basin, which is characterized by halocline salinification and the uplift of the boundary between the halocline and the Atlantic Water layer. Contemporarily, the sea ice decline caused a strong warming trend in the Atlantic Water layer. The Empirical Orthogonal Function (EOF) analysis of Arctic annual sea surface height for this period reveals that the first two modes of the upper ocean circulation have active centers associated with the Arctic Oscillation and Beaufort High variability, respectively. In the presence of sea ice decline the first two EOFs can better distinguish the ocean variability driven by the two atmospheric circulation modes. Therefore, the major changes in the Arctic Ocean in the past two decades are indicators of climate change as is the sea ice retreat. Our synthesis could help assess how the Arctic Ocean might change in future warming climate.

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39

De Rovere, Francesco, Leonardo Langone, Katrin Schroeder, Stefano Miserocchi, Federico Giglio, Stefano Aliani y Jacopo Chiggiato. "Water Masses Variability in Inner Kongsfjorden (Svalbard) During 2010–2020". Frontiers in Marine Science 9 (27 de enero de 2022). http://dx.doi.org/10.3389/fmars.2022.741075.

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Kongsfjorden is an Arctic fjord located in the Svalbard archipelago. Its hydrography is influenced by the warm and saline Atlantic Water (AW) in the West Spitsbergen Current and the cold and fresh Polar Water circulating on the shelf. We assess the so-called atlantification of Kongsfjorden in the 2010–2020 decade by inspecting modifications in water properties and water masses variability through moored data and summer CTD surveys. Atlantification in this fjord has emerged as an increasing temperature and salinity, resulting from enhanced advection of Atlantic waters from the West Spitsbergen Current. The water column in inner Kongsfjorden warmed by 0.13°C/yr at 35 m and 0.06°C/yr at 85 m depth from 2010 to 2020, while salinity increased by 0.3 PSU. Depth-averaged temperatures have increased by 0.26°C/yr in the warmest months of the year, whereas they appear relatively stable in the coldest months. Both temperature and salinity present a linear regression change point in January 2017, with latter years featuring decreasing values. Highly diluted AW is found at the beginning of the decade, which give way to more and more pure AW in latter years, culminating in extensive intrusions in 2016 and 2017 determining the warmest and saltiest conditions over the decade in inner Kongsfjorden. Observations in the 2010–2020 decade confirm that Kongsfjorden has transitioned to an Atlantic-type fjord, featuring depleted sea ice conditions and rather regular shallow intrusions of AW in summer and frequently also in winter. Although single intrusions of AW are associated with dynamical events on the shelf, we found that the long-term temperature evolution in the inner Kongsfjord is consistent with the meridional temperature transport of the West Spitsbergen Current. The AW current flowing northward from lower latitudes along the western Svalbard archipelago thus has profoundly driven local conditions in the inner fjord in this decade.

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40

Mańko, Maciej K., Małgorzata Merchel, Sławomir Kwaśniewski y Agata Weydmann‐Zwolicka. "Atlantification alters the reproduction of jellyfish Aglantha digitale in the European Arctic". Limnology and Oceanography, 16 de junio de 2022. http://dx.doi.org/10.1002/lno.12170.

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41

Grabowski, Michał, Aleksandra Jabłońska, Agata Weydmann-Zwolicka, Mikhail Gantsevich, Petr Strelkov, Maria Skazina y Jan Marcin Węsławski. "Contrasting molecular diversity and demography patterns in two intertidal amphipod crustaceans reflect Atlantification of High Arctic". Marine Biology 166, n.º 12 (11 de noviembre de 2019). http://dx.doi.org/10.1007/s00227-019-3603-4.

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Abstract The distribution of two common intertidal amphipod species Gammarus oceanicus and Gammarus setosus was studied along the coast of Svalbard Archipelago. Genetic analysis showed geographical homogeneity of G. oceanicus with only one molecular operational taxonomic unit (MOTU) and much higher diversification of G. setosus (5 MOTUs) in the studied area. Only two MOTUs of G. setosus are widespread along the whole studied Svalbard coastline, whereas the remaining three MOTUs are present mainly along the northern and eastern parts of archipelago’s largest island, Spitsbergen. Distribution analysis indicates that the demographic and spatial expansion of G. oceanicus in the northern Atlantic has started already during the Last Glacial Maximum (LGM, ca. 18 ka), while G. setosus seems to be a long-persistent inhabitant of the Arctic, possibly even through the LGM, with slower distribution dynamics. Combining the results of our molecular study with previous field observations and the knowledge upon the direction of ocean currents around the Svalbard Archipelago, it can be assumed that G. oceanicus is a typical boreal Atlantic species that is still continuing its postglacial expansion northwards. In recent decades it colonized High Arctic due to the climate warming and has partly displaced G. setosus, that used to be the only common gammarid of the Svalbard intertidal zone.

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42

Shu, Qi, Qiang Wang, Zhenya Song y Fangli Qiao. "The poleward enhanced Arctic Ocean cooling machine in a warming climate". Nature Communications 12, n.º 1 (20 de mayo de 2021). http://dx.doi.org/10.1038/s41467-021-23321-7.

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AbstractAs a cooling machine of the Arctic Ocean, the Barents Sea releases most of the incoming ocean heat originating from the North Atlantic. The related air-sea heat exchange plays a crucial role in both regulating the climate and determining the deep circulation in the Arctic Ocean and beyond. It was reported that the cooling efficiency of this cooling machine has decreased significantly. In this study, we find that the overall cooling efficiency did not really drop: When the cooling efficiency decreased in the southern Barents Sea, it increased in the northern Barents and Kara Seas, indicating that the cooling machine has expanded poleward. According to climate model projections, it is very likely that the cooling machine will continue to expand to the Kara Sea and then to the Arctic Basin in a warming climate. As a result, the Arctic Atlantification will be enhanced and pushed poleward in the future.

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43

Sicard, Marie, Agatha M. de Boer, Helen K. Coxall, Torben Koenigk, Mehdi Pasha Karami, Martin Jakobsson y Matt O’Regan. "Similarities and Differences in Arctic Sea‐Ice Loss During the Solar‐Forced Last Interglacial Warming (127 Kyr BP) and CO₂‐Forced Future Warming". Geophysical Research Letters 50, n.º 24 (12 de diciembre de 2023). http://dx.doi.org/10.1029/2023gl104782.

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AbstractBased on a 7‐member global circulation model ensemble from CMIP6/PMIP4, we compare the regional distribution of Arctic sea ice between a simulation representing the Last Interglacial (LIG) climate, with solar‐forced warming, and an idealized future CO2‐forced simulation with a similar annual sea‐ice volume. The two simulations feature small but robust differences in the Central Arctic and Baffin Bay during summer, and larger differences at the sea‐ice margins in the sub‐Arctic Atlantic and North Pacific sectors during winter. Our results indicate that, under both forcings, sea ice persists north of Greenland until late summer, suggesting that the assumption that this region is the “Last Ice Area” is robust and holds for other climate states. However, we show that processes influencing sea‐ice distribution in winter, such as Atlantification and sea‐ice drift, differ and need to be further investigated.

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44

Gjelstrup, Caroline V. B., Mikael K. Sejr, Laura de Steur, Jørgen Schou Christiansen, Mats A. Granskog, Boris P. Koch, Eva Friis Møller, Mie H. S. Winding y Colin A. Stedmon. "Vertical redistribution of principle water masses on the Northeast Greenland Shelf". Nature Communications 13, n.º 1 (10 de diciembre de 2022). http://dx.doi.org/10.1038/s41467-022-35413-z.

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AbstractThe Northeast Greenland shelf (NEGS) is a recipient of Polar Water (PW) from the Arctic Ocean, Greenland Ice Sheet melt, and Atlantic Water (AW). Here, we compile hydrographical measurements to quantify long-term changes in fjords and coastal waters. We find a profound change in the vertical distribution of water masses, with AW shoaling >60 m and PW thinning >50 m since early 2000’s. The properties of these waters have also changed. AW is now 1 °C warmer and the salinity of surface waters and PW are 1.8 and 0.68 lower, respectively. The AW changes have substantially weakened stratification south of ~74°N, indicating increased accessibility of heat and potentially nutrients associated with AW. The Atlantification earlier reported for the eastern Fram Strait and Barents Sea region has also propagated to the NEGS. The increased presence of AW, is an important driver for regional change leading to a likely shift in ecosystem structure and function.

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45

Schiaparelli, Stefano, Maria Chiara Alvaro, Alice Guzzi y Marco Grillo. "Cymbulia parvidentata Pelseneer, 1888 (Mollusca, Cymbuliidae) in the Ligurian Sea: further evidence of Atlantic species incursions in the Mediterranean area". Biodiversity Data Journal 11 (21 de febrero de 2023). http://dx.doi.org/10.3897/bdj.11.e99108.

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We report the first record of a stranded specimen of Cymbulia parvidentata, a pteropod species of Atlantic origin, in the Ligurian Sea. On 27 February 2022, six C. peronii and one C. parvidentata were collected on Borgio-Verezzi Beach (Savona, Italy - 44.16° N, 8.304633° W). Specimens were examined morphologically and biometrically. Measurements (length, width, height and wet weight) separated the two taxa, C. peronii being larger than C. parvidentata. The finding of C. parvidentata, which has only occasionally been reported in southern Italy, is remarkable and may be due to ascending Atlantic water (AW) pulses that reach the Ligurian Sea. This finding adds to the previous knowledge of other pelagic species of Atlantic origin that were found in the Ligurian Sea, suggesting the possibility of major on-going changes and a general “Atlantification”. In order to determine the frequency of such events, it will be highly desirable to design specific citizen-science campaigns.

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46

Jordán, Ferenc, Greta Capelli, Raul Primicerio y Antonio Bodini. "Strongly asymmetric interactions and control regimes in the Barents Sea: a topological food web analysis". Frontiers in Marine Science 11 (22 de abril de 2024). http://dx.doi.org/10.3389/fmars.2024.1301612.

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IntroductionIncreasing temperature of the global ocean alters the spatial behavior of a number of species. From the northern Atlantic Ocean, species may shift their area towards the poles. This results in the atlantification of the Barents Sea, raising questions about possible changes in species composition, community structure and community control.MethodsWe address the question whether possible changes in community control can be detected and quantified based on simple network analytical measures applied to the food web. Based on unweighted (binary) and undirected (symmetric) data, we quantify the strength of direct and indirect interactions in the network, represent the most asymmetric effects in the asymmetry graph composed of directed and weighted links and study the overlap among trophic niches of organisms.Results and discussionWe support earlier findings suggesting that the ecosystem can possibly be characterized by wasp-waist control. This would mean that focusing management efforts on intermediate trophic levels is of high importance, providing indirect benefit for organisms also at lower and higher trophic levels.

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47

Kappel, Ellen. "The Arctic Ocean: Round Two". Oceanography, 2022. http://dx.doi.org/10.5670/oceanog.2022.137.

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Every decade or so, it is worth revisiting a topic that we previously covered in Oceanography to provide the community with updates on progress. This special issue on The New Arctic Ocean is the latest example. In 2011, we published a special issue on The Changing Arctic Ocean (https://tos.org/oceanography/issue/volume-24-issue-03) featuring some of the advances made in polar science resulting from the International Polar Year of 2007–2008. Articles in this current special issue further explore the continuing, profound, and increasingly rapid changes occurring in the Arctic Ocean, illuminated by another decade of advances in data collection, analysis, and computation, and enriched by infusions of Indigenous knowledge. Continued warming of the “new” Arctic Ocean, which is already exhibiting further sea ice decline and “Atlantification,” more coastal erosion, the potential for more frequent and larger harmful algal blooms, and alterations to ecosystem functioning, among other significant changes, is of great consequence to local coastal communities’ food security and infrastructure, and some changes, such as sea ice decline, likely have global implications.

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48

Edwards, Martin, Pierre Hélaouët, Eric Goberville, Alistair Lindley, Geraint A. Tarling, Michael T. Burrows y Angus Atkinson. "North Atlantic warming over six decades drives decreases in krill abundance with no associated range shift". Communications Biology 4, n.º 1 (31 de mayo de 2021). http://dx.doi.org/10.1038/s42003-021-02159-1.

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AbstractIn the North Atlantic, euphausiids (krill) form a major link between primary production and predators including commercially exploited fish. This basin is warming very rapidly, with species expected to shift northwards following their thermal tolerances. Here we show, however, that there has been a 50% decline in surface krill abundance over the last 60 years that occurred in situ, with no associated range shift. While we relate these changes to the warming climate, our study is the first to document an in situ squeeze on living space within this system. The warmer isotherms are shifting measurably northwards but cooler isotherms have remained relatively static, stalled by the subpolar fronts in the NW Atlantic. Consequently the two temperatures defining the core of krill distribution (7–13 °C) were 8° of latitude apart 60 years ago but are presently only 4° apart. Over the 60 year period the core latitudinal distribution of euphausiids has remained relatively stable so a ‘habitat squeeze’, with loss of 4° of latitude in living space, could explain the decline in krill. This highlights that, as the temperature warms, not all species can track isotherms and shift northward at the same rate with both losers and winners emerging under the ‘Atlantification’ of the sub-Arctic.

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49

Dörr, Jakob, Marius Årthun, Tor Eldevik y Erica Madonna. "Mechanisms of regional winter sea-ice variability in a warming Arctic". Journal of Climate, 10 de agosto de 2021, 1–56. http://dx.doi.org/10.1175/jcli-d-21-0149.1.

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AbstractThe Arctic winter sea-ice cover is in retreat overlaid by large internal variability. Changes to sea ice are driven by exchange of heat, momentum and freshwater within and between the ocean and the atmosphere. Using a combination of observations and output from the Community Earth System Model Large Ensemble, we analyze and contrast present and future drivers of the regional winter sea-ice cover. Consistent with observations and previous studies, we find that for the recent decades ocean heat transport though the Barents Sea and Bering Strait is a major source of sea-ice variability in the Atlantic and Pacific sectors of the Arctic, respectively. Future projections show a gradually expanding footprint of Pacific and Atlantic inflows highlighting the importance of future Atlantification and Pacification of the Arctic Ocean. While the dominant hemispheric modes of winter atmospheric circulation are only weakly connected to the sea ice, we find distinct local atmospheric circulation patterns associated with present and future regional sea-ice variability in the Atlantic and Pacific sectors, consistent with heat and moisture transport from lower latitudes. Even if the total freshwater input from rivers is projected to increase substantially, its influence on simulated sea ice is small in the context of internal variability.

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50

Jory, Cabrol, Véronique Lesage, Alexandra Leclerc, Janie Giard, Sara Iverson, Martine Bérubé, Robert Michaud y Christian Nozais. "Individual and population dietary specialization decline in fin whales during a period of ecosystem shift". Scientific Reports 11, n.º 1 (25 de agosto de 2021). http://dx.doi.org/10.1038/s41598-021-96283-x.

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AbstractThis study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998–2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species, and diet was quantitatively assessed using Bayesian isotopic models. An abrupt change in fin whale dietary niche coincided with a decrease in biomass of their predominant prey, Arctic krill (Thysanoessa spp.). This dietary niche widening toward generalist diets occurred in nearly 60% of sampled individuals. The fin whale population, typically composed of specialists of either krill or lipid-rich pelagic fishes, shifted toward one composed either of krill specialists or true generalists feeding on various zooplankton and fish prey. This change likely reduced intraspecific competition. In the context of the current “Atlantification” of northern water masses, our findings emphasize the importance of considering individual-specific foraging tactics and not only population or group average responses when assessing population resilience or when implementing conservation measures.

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