Particulate organic carbon export across the Antarctic Circumpolar Current at 10°E: Differences between north and south of the Antarctic Polar Front

Puigcorbé, Viena; Roca‐Martí, Montserrat; Masqué, Pere; Benítez-Nelson, Claudia R.; Loeff, Michiel Rutgers v. d.; Laglera, Luis M.; Bracher, Astrid; Cheah, Wee; Strass, Volker; Hoppema, Mario; Santos-Echeandía, Juan; Hunt, Brian P. V.; Pakhomov, Evgeny A.; Klaas, Christine

doi:10.1016/j.dsr2.2016.05.016

Cited by 24 publications

(21 citation statements)

References 109 publications

(66 reference statements)

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“…The main difference is a significant increase of carbon export in the PHYSIO experiment in regions where export is already low (Figure b). These increased values of carbon export remain within the range of observations (Ducklow et al, ; Laurenceau‐Cornec et al, ; Morris et al, ; Puigcorbé et al, ; Roca‐Martí et al, ).…”

Section: Resultssupporting

confidence: 83%

The Biological Pump and Seasonal Variability of pCO₂ in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

2018

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Iron is known to limit primary production in the Southern Ocean (SO). To cope with the lack of this micronutrient, diatoms, a dominant phytoplankton group in this oceanic region, have been shown in cultures to have developed an original adaptation strategy to maintain efficient growth rates despite very low cellular iron quotas, even in low light conditions. Using a global ocean biogeochemical model, we explored the consequences of this physiological adaptation for the biological pump and the seasonal variability of both surface chlorophyll concentrations and surface partial pressure of carbon dioxide (pCO2) in this key region for global climate. In the model, we implemented a low intracellular Fe:C requirement in the SO for diatoms uniquely. This results in an increase of 10% in the relative contribution of diatoms to total SO primary production. The biological pump is also strengthened, which increases the biological contribution to the seasonal evolution of pCO2 relative to the thermodynamic component. Therefore, the seasonal evolution of both surface chlorophyll and surface pCO2 is significantly impacted, with a marked improvement, in our model, in the SO polar zone compared to the observations. Our model study underscores the potentially important consequences that this adaptive physiological behavior of diatoms could have on marine biogeochemistry in the SO. It is thus critical to improve our understanding of the physiology of this key phytoplankton group, in particular in the SO.

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Section: Resultssupporting

confidence: 83%

The Biological Pump and Seasonal Variability of pCO₂ in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

2018

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“…Indeed, we found an inverse relationship between export efficiency and NPP (p o0.05; ST method: ρ¼ À0.95, n ¼8; SWST method: ρ¼ À0.89, n¼ 6) supporting recent observations (Cavan et al, 2015;Laurenceau-Cornec et al, 2015;Maiti et al, 2013). This relationship could be explained by a combination of temporal decoupling between primary production and export (Henson et al, 2015;Puigcorbé et al, 2017), and other processes such as zooplankton grazing (Cavan et al, 2015), bacterial activity and recycling efficiency (Maiti et al, 2013).…”

Section: Export Efficiencysupporting

confidence: 69%

“…This was attributed to changes in the nature of the sinking particles (less labile or more rapidly sinking) and/or less efficient biological and physical processes responsible for particle break-up and consumption below the bloom. Th and PON/ 234 Th ratios in particles C/Th and N/Th ratios were 410 μmol C dpm À 1 (average: 15 75 μmol C dpm À 1 ) and 41 μmol N dpm À 1 (average: 2 71 μmol N dpm À 1 ), respectively, in all samples collected either with ST or ISP ( 453 μm) at 100 m. Overall, these values were higher than those reported by most studies conducted in the Southern Ocean (Buesseler et al, , 2001aCoppola et al, 2005;Jacquet et al, 2011;Martin et al, 2013;Morris et al, 2007;Planchon et al, 2013;Rutgers van der Loeff et al, 2011Savoye et al, 2008), but similar to others (Cochran et al, 2000;Puigcorbé et al, 2017;Rutgers van der Loeff et al, 2002;Smetacek et al, 2012). Multiple factors may have played a role in shaping the C/Th and N/Th ratios, such as particle source, sinking velocity, Th speciation and remineralisation of C, N and 234 Th associated with sinking particles .…”

Section: Results and Comparison With Other Studiescontrasting

confidence: 52%

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Roca‐Martí

Puigcorbé

Iversen

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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a b s t r a c tCarbon fixation by phytoplankton plays a key role in the uptake of atmospheric CO 2 in the Southern Ocean. Yet, it still remains unclear how efficiently the particulate organic carbon (POC) is exported and transferred from ocean surface waters to depth during phytoplankton blooms. In addition, little is known about the processes that control the flux attenuation within the upper twilight zone. Here, we present results of downward POC and particulate organic nitrogen fluxes during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean in summer 2012. We used thorium-234 ( 234 Th) as a particle tracer in combination with drifting sediment traps (ST). Their simultaneous use evidenced a sustained high export rate of 234 Th at 100 m depth in the weeks prior to and during the sampling period. The entire study area, of approximately 8000 km 2 , showed similar vertical export fluxes in spite of the heterogeneity in phytoplankton standing stocks and productivity, indicating a decoupling between production and export. The POC fluxes at 100 m were high, averaging 26 715 mmol C m À 2 d À 1 , although the strength of the biological pump was generally low. Only o 20% of the daily primary production reached 100 m, presumably due to an active recycling of carbon and nutrients. Pigment analyses indicated that direct sinking of diatoms likely caused the high POC transfer efficiencies ( $ 60%) observed between 100 and 300 m, although faecal pellets and transport of POC linked to zooplankton vertical migration might have also contributed to downward fluxes.

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“…3A. Indeed, this 234 Th equilibrium depth has been used by Puigcorbé et al (22) and Lemaitre et al (23) as their particle export reference depth, rather than a PAR-or a chlorophyll-based boundary. The 234 Th excess immediately below Ez 0.1 is most conspicuous with high-verticalresolution 234 Th data, such as the example from a 17-depth profile of 234 Th and fluorescence in the NW Pacific (Fig.…”

Section: Choosing a Biogeochemically Relevant Reference Depthmentioning

confidence: 99%

Metrics that matter for assessing the ocean biological carbon pump

Buesseler

Boyd

Black

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

182

158

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The biological carbon pump (BCP) comprises wide-ranging processes that set carbon supply, consumption, and storage in the oceans’ interior. It is becoming increasingly evident that small changes in the efficiency of the BCP can significantly alter ocean carbon sequestration and, thus, atmospheric CO2 and climate, as well as the functioning of midwater ecosystems. Earth system models, including those used by the United Nation’s Intergovernmental Panel on Climate Change, most often assess POC (particulate organic carbon) flux into the ocean interior at a fixed reference depth. The extrapolation of these fluxes to other depths, which defines the BCP efficiencies, is often executed using an idealized and empirically based flux-vs.-depth relationship, often referred to as the “Martin curve.” We use a new compilation of POC fluxes in the upper ocean to reveal very different patterns in BCP efficiencies depending upon whether the fluxes are assessed at a fixed reference depth or relative to the depth of the sunlit euphotic zone (Ez). We find that the fixed-depth approach underestimates BCP efficiencies when the Ez is shallow, and vice versa. This adjustment alters regional assessments of BCP efficiencies as well as global carbon budgets and the interpretation of prior BCP studies. With several international studies recently underway to study the ocean BCP, there are new and unique opportunities to improve our understanding of the mechanistic controls on BCP efficiencies. However, we will only be able to compare results between studies if we use a common set of Ez-based metrics.

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Particulate organic carbon export across the Antarctic Circumpolar Current at 10°E: Differences between north and south of the Antarctic Polar Front

Cited by 24 publications

References 109 publications

The Biological Pump and Seasonal Variability of pCO₂ in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

The Biological Pump and Seasonal Variability of pCO₂ in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Metrics that matter for assessing the ocean biological carbon pump

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Particulate organic carbon export across the Antarctic Circumpolar Current at 10°E: Differences between north and south of the Antarctic Polar Front

Cited by 24 publications

References 109 publications

The Biological Pump and Seasonal Variability of pCO2 in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

The Biological Pump and Seasonal Variability of pCO2 in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Metrics that matter for assessing the ocean biological carbon pump

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Product

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The Biological Pump and Seasonal Variability of pCO₂ in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

The Biological Pump and Seasonal Variability of pCO₂ in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron