Responses in Arctic marine carbon cycle processes: conceptual scenarios and implications for ecosystem function

Findlay, Helen S.; Gibson, Georgina A.; Kędra, Monika; Morata, Nathalie; Orchowska, M. I.; Pavlov, Alexey K.; Reigstad, Marit; Silyakova, Anna; Tremblay, Jean‐Éric; Walczowski, Waldemar; Weydmann, Agata; Logvinova, Christie

doi:10.3402/polar.v34.24252

Cited by 22 publications

(32 citation statements)

References 185 publications

(184 reference statements)

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“…According to the classification of Carmack et al (2006), the Barents Sea is considered an "inflow" shelf sea or an Atlantic-influenced shelf sea (Findlay et al, 2015). The general inflow of warm and salty water from the Atlantic keeps a large part of the Barents Sea ice-free all year round.…”

Section: Introductionmentioning

confidence: 99%

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The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

et al. 2017

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Abstract. The Arctic is undergoing dramatic changes which cover the entire range of natural processes, from extreme increases in the temperatures of air, soil, and water, to changes in the cryosphere, the biodiversity of Arctic waters, and land vegetation. Small changes in the largest marine carbon pool, the dissolved inorganic carbon pool, can have a profound impact on the carbon dioxide (CO 2 ) flux between the ocean and the atmosphere, and the feedback of this flux to climate. Knowledge of relevant processes in the Arctic seas improves the evaluation and projection of carbon cycle dynamics under current conditions of rapid climate change.Investigation of the CO 2 system in the outer shelf and continental slope waters of the Eurasian Arctic seas (the Barents, Kara, Laptev, and East Siberian seas) during 2006, 2007, and 2009 revealed a general trend in the surface water partial pressure of CO 2 (pCO 2 ) distribution, which manifested as an increase in pCO 2 values eastward. The existence of this trend was defined by different oceanographic and biogeochemical regimes in the western and eastern parts of the study area; the trend is likely increasing due to a combination of factors determined by contemporary change in the Arctic climate, each change in turn evoking a series of synergistic effects. A high-resolution in situ investigation of the carbonate system parameters of the four Arctic seas was carried out in the warm season of 2007; this year was characterized by the next-to-lowest historic sea-ice extent in the Arctic Ocean, on satellite record, to that date. The study showed the different responses of the seawater carbonate system to the environment changes in the western vs. the eastern Eurasian Arctic seas. The large, open, highly productive water area in the northern Barents Sea enhances atmospheric CO 2 uptake. In contrast, the uptake of CO 2 was strongly weakened in the outer shelf and slope waters of the East Siberian Arctic seas under the 2007 environmental conditions. The surface seawater appears in equilibrium or slightly supersaturated by CO 2 relative to atmosphere because of the increasing influence of river runoff and its input of terrestrial organic matter that mineralizes, in combination with the high surface water temperature during sea-ice-free conditions. This investigation shows the importance of processes that vary on small scales, both in time and space, for estimating the air-sea exchange of CO 2 . It stresses the need for highresolution coverage of ocean observations as well as time series. Furthermore, time series must include multi-year studies in the dynamic regions of the Arctic Ocean during these times of environmental change.

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Section: Introductionmentioning

confidence: 99%

“…The other shelf seas (the Kara, Laptev, and East Siberian seas) are classified as "interior" shelf seas (Carmack et al, 2006) or as river-influenced shelf seas (Findlay et al, 2015). The river discharge as well as the seasonal formation and melting of sea ice greatly impact the hydrology and chemistry of these shelf seas.…”

Section: Introductionmentioning

confidence: 99%

The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

et al. 2017

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“…Simultaneously, response of terrestrial ecosystems to temperature increase will accelerate permafrost thaw and increase the riverine discharge, resulting in more allochthonous (terrestrial) DOM being released into the Arctic Ocean (Amon, 2004;Stedmon et al, 2011;Anderson and Amon, 2015;Prowse et al, 2015, and references therein). Terrestrial DOM plays a considerable role in the carbon budget of the Arctic Ocean (Findlay et al, 2015;Stein and Macdonald, 2004), especially in coastal waters and the continental shelf with a large inflow of terrestrial DOM, which constitutes 80 % of total organic carbon delivered by Arctic rivers .…”

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confidence: 99%

“…Recent studies have reported intensification of AW inflow into the Arctic Ocean (Walczowski, 2014;Polyakov et al, 2017;Walczowski et al, 2017), further highlighting the importance of the European sector of the Arctic Ocean to better understand the complex interactions between inflowing AW and PSW. Optically these waters are contrasting, especially with respect to CDOM (Granskog et al, 2012;Pavlov et al, 2015; and FDOM (Jørgensen et al, 2014;Gonçalves-Araujo et al, 2016). In the absence of sea ice, favorable vertical mixing conditions and sufficient levels of solar radiation make it a very productive and important region from an ecosystem and socioeconomic standpoint, thus ensuring motivation for ongoing studies of the complex marine system in the area (Skogen et al, 2007;Olsen et al, 2009;Dalpadado et al, 2014).…”

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confidence: 99%

“…In the absence of sea ice, favorable vertical mixing conditions and sufficient levels of solar radiation make it a very productive and important region from an ecosystem and socioeconomic standpoint, thus ensuring motivation for ongoing studies of the complex marine system in the area (Skogen et al, 2007;Olsen et al, 2009;Dalpadado et al, 2014). In the context of ongoing and further anticipated intensification of Atlantic Ocean inflow to the Arctic Ocean, a description of processes and factors controlling CDOM and FDOM properties and distribution could be used to better predict future changes associated with CDOM in the areas upstream of the AW inflow region, to estimate glacial meltwater , and to trace water masses (Gonçalves-Araujo et al, 2016).…”

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Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

et al. 2018

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Abstract. Optical properties of chromophoric (CDOM) and fluorescent dissolved organic matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June-July 2013, 2014, and 2015. The CDOM absorption coefficient at 350 nm, a CDOM (350) showed significant interannual variation (T test, p < 0.00001). In 2013, the highest average a CDOM (350) values (a CDOM (350) = 0.30 ± 0.12 m −1 ) were observed due to the influence of cold and low-salinity water from the Sørkapp Current (SC) in the southern part of the West Spitsbergen Shelf. In 2014, a CDOM (350) values were significantly lower (T test, p < 0.00001) than in 2013 (average a CDOM (350) = 0.14 ± 0.06 m −1 ), which was associated with the dominance of warm and saline Atlantic Water (AW) in the region, while in 2015 intermediate CDOM absorption (average a CDOM (350) = 0.19 ± 0.05 m −1 ) was observed. In situ measurements of three FDOM components revealed that fluorescence intensity of protein-like FDOM dominated in the surface layer of the Nordic Seas. Concentrations of marine and terrestrial humic-like DOM were very low and distribution of those components was generally vertically homogenous in the upper ocean (0-100 m). Fluorescence of terrestrial and marine humic-like DOM decreased in surface waters (0-15 m) near the sea ice edge due to dilution of oceanic waters by sea ice meltwater. The vertical distribution of protein-like FDOM was characterized by a prominent subsurface maximum that matched the subsurface chlorophyll a maximum and was observed across the study area. The highest protein-like FDOM fluorescence was observed in the Norwegian Sea in the core of warm AW. There was a significant relationship between the proteinlike fluorescence and chlorophyll a fluorescence (R 2 = 0.65, p < 0.0001, n = 24 490), which suggests that phytoplankton was the primary source of protein-like DOM in the Nordic Seas and West Spitsbergen Shelf waters. Observed variability in selected spectral indices (spectral slope coefficient, S 300-600 , carbon-specific CDOM absorption coefficient at 254 and 350 nm, SUVA 254 , a * CDOM (350)) and the nonlinear relationship between CDOM absorption and the spectral slope coefficient also indicate a dominant marine (autochthonous) source of CDOM and FDOM in the study area. Further, our data suggest that a CDOM (350) cannot be used to predict dissolved organic carbon (DOC) concentrations in the study region; however the slope coefficient (S 300-600 ) shows some promise in being used.

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Organic matter remineralization in marine sediments: A Pan‐Arctic synthesis

Bourgeois

Archambault

Witte

2017

Global Biogeochemical Cycles

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Climate change in the Arctic is ongoing and causes drastic modification on the ecosystem functioning. In soft-bottom environments, organic matter remineralization is considered an important ecosystem function. Here we provide a large-scale assessment of the current knowledge on the benthic organic matter remineralization and its potential response to climate change. Sediment oxygen demand (SOD) values (n = 1154), measured throughout the Arctic, were gathered from 30 publications and 16 databases, and nutrient flux values, available in a far lesser extent (n < 80), were also compiled. Generalized additive models were used to estimate the influence of explanatory variables on benthic oxygen fluxes and for interpolating SOD to the whole Arctic region. This first Pan-Arctic review of the distributions of SOD showed that oxygen fluxes strongly depended on water depth, i.e., followed the general trend observed for other regions, and also on the availability of labile organic matter. The continental shelves (representing~50% of Arctic Ocean's total area) were characterized by the highest SOD values (10.5 ± 7.9 mmol O 2 m À2 d À1 ), and differences among shelves were observed; SOD values in inflow, interior, and outflow shelves were 11.8 ± 8.0, 6.2 ± 5.6, and 3.9 ± 3.5 mmol O 2 m À2 d À1 , respectively. Moreover, seasonal variation in SOD changed significantly among areas. The interpolation based on the best fitted model showed high respiration in the inflow and interior shelves. In the inflow shelves, characterized by productive waters, benthic activities replenish bottom water with nutrients which may augment primary productivity, whereas sediments from the interior shelves, e.g., under the direct influence of the Mackenzie River, consume nutrients.

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Responses in Arctic marine carbon cycle processes: conceptual scenarios and implications for ecosystem function

Cited by 22 publications

References 185 publications

The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

Organic matter remineralization in marine sediments: A Pan‐Arctic synthesis

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Responses in Arctic marine carbon cycle processes: conceptual scenarios and implications for ecosystem function

Cited by 22 publications

References 185 publications

The spatial and interannual dynamics of the surface water carbonate system and air–sea CO&lt;sub&gt;2&lt;/sub&gt; fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

The spatial and interannual dynamics of the surface water carbonate system and air–sea CO&lt;sub&gt;2&lt;/sub&gt; fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

Organic matter remineralization in marine sediments: A Pan‐Arctic synthesis

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Product

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The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean