Estimates of net community production in the Southern Ocean determined from time series observations (2002–2011) of nutrients, dissolved inorganic carbon, and surface ocean pCO2 in Drake Passage

Abstract. Net community production (NCP) and ratios of carbon to nutrient consumption were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, West Spitsbergen, during June–July 2010. Nutrient-deplete fjord water with natural phyto- and bacteriaplankton assemblages, enclosed in nine mesocosms of ~ 50 m3 volume, was exposed to pCO2 levels ranging from 185 to 1420 μatm on initial state. Mean values of pCO2 levels during experiment ranged from 175 to 1085 μatm in different mesocosms. Phytoplankton growth was stimulated by nutrient addition. In this study NCP is estimated as a cumulative change in dissolved inorganic carbon concentrations. Stoichiometric couping between inorganic carbon and nutrient is shown as a ratio of a cumulative NCP to a cumulative change in inorganic nutrients. Three peaks of chlorophyll a concentration occurred during the experiment. Accordingly the experiment was divided in three phases. Overall cumulative NCP was similar in all mesocosms by the final day of experiment. However, NCP varied among phases, showing variable response to CO2 perturbation. Carbon to nitrogen (C : N) and carbon to phosphorus (C : P) uptake ratios were estimated only for the period after nutrient addition (post-nutrient period). For the total post-nutrient period ratios were close to Redfield proportions, however varied from it in different phases. The response of C : N and C : P uptake ratios to CO2 perturbation was different for three phases of the experiment, reflecting variable NCP and dependence on changing microbial community. Through the variable NCP, C : N and C : P uptake ratios for 31 days of the experiment we show a flexibility of biogeochemical response establishing a strong microbial loop in Kongsfjorden under different CO2 scenarios.

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Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

Biogeosciences Discussions ◽

10.5194/bgd-7-251-2010 ◽

2010 ◽

Vol 7 (1) ◽

pp. 251-300 ◽

Cited By ~ 3

Author(s):

J. T. Mathis ◽

J. N. Cross ◽

N. R. Bates ◽

S. B. Moran ◽

M. W. Lomas ◽

...

Keyword(s):

Primary Production ◽

Bering Sea ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Inner Shelf ◽

Net Community Production ◽

Important Indicator ◽

Bering Sea Shelf ◽

Community Production ◽

The Bering Sea

Abstract. The southeastern shelf of the Bering Sea is one of the ocean's most productive ecosystems and sustains more than half of the total US fish landings annually. However, the character of the Bering Sea shelf ecosystem has undergone a dramatic shift over the last several decades, causing notable increases in the dominance of temperate features coupled to the decline of arctic species and decreases in the abundance of commercially important organisms. In order to assess the current state of primary production in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC) concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmol kg−1 over the inner shelf to ~2400 μmol kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt and primary production. Concentrations were found to be as low ~1800 μmol kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmol kg−1 in the upper 30 m of the water column due to primary production between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of net community production (NCP) on the inner, middle, and outer shelf averaged 28±10 mmol C m−2 d−1. However, higher rates of NCP (40–47 mmol C m−2 d−1) were observed in the ''Green Belt'' where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total productivity across the shelf was on the order of ~105 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning.

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Fluxes of carbon and nutrients to the Iceland Sea surface layer and inferred primary productivity and stoichiometry

Biogeosciences Discussions ◽

10.5194/bgd-11-15399-2014 ◽

2014 ◽

Vol 11 (11) ◽

pp. 15399-15433

Author(s):

E. Jeansson ◽

R. G. J. Bellerby ◽

I. Skjelvan ◽

H. Frigstad ◽

S. R. Ólafsdóttir ◽

...

Keyword(s):

Surface Layer ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Vertical Mixing ◽

Sea Surface ◽

Net Community Production ◽

Horizontal Advection ◽

Vertical Fluxes ◽

Biological Uptake ◽

Community Production

Abstract. Fluxes of carbon and nutrients to the upper 100 m of the Iceland Sea are evaluated. The study utilises hydro-chemical data from the Iceland Sea time-series station (68.00° N, 12.67° W), for the years between 1993 and 2006. By comparing data of dissolved inorganic carbon (DIC) and nutrients in the surface layer (upper 100 m), and a sub-surface layer (100–200 m), we calculate monthly deficits in the surface, and use these to deduce the surface layer fluxes that affect the deficits: vertical mixing, horizontal advection, air–sea exchange, and biological activity. The deficits show a clear seasonality with a minimum in winter, when the mixed layer is at the deepest, and a maximum in early autumn, when biological uptake has removed much of the nutrients. The annual vertical fluxes of DIC and nitrate amounts to 1.7 ± 0.3 and 0.23 ± 0.07 mol m−2 yr−1, respectively, and the annual air–sea uptake of atmospheric CO2 is 4.4 ± 1.1 mol m−2 yr−1. The biologically driven changes in DIC during the year relates to net community production (NCP), and the net annual NCP corresponds to export production, and is here calculated to 6.1 ± 0.9 mol C m−2 yr−1. The typical, median C : N ratio during the period of net community uptake is 11, and thus clearly higher than Redfield, but is varying during the season.

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Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

Biogeosciences ◽

10.5194/bg-7-1769-2010 ◽

2010 ◽

Vol 7 (5) ◽

pp. 1769-1787 ◽

Cited By ~ 38

Author(s):

J. T. Mathis ◽

J. N. Cross ◽

N. R. Bates ◽

S. Bradley Moran ◽

M. W. Lomas ◽

...

Keyword(s):

Primary Production ◽

Bering Sea ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Inner Shelf ◽

Net Community Production ◽

Important Indicator ◽

Carbonate Formation ◽

Community Production ◽

The Bering Sea

Abstract. In order to assess the current state of net community production (NCP) in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC) concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmoles kg−1 over the inner shelf to ~2400 μmoles kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt, terrestrial inputs, and primary production. Concentrations were found to be as low ~1800 μmoles kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmoles kg−1 in the upper 30 m of the water column due to primary production and calcium carbonate formation between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of NCP on the inner, middle, and outer shelf averaged 28 ± 9 mmoles C m−2 d−1. However, higher rates of NCP (40–47 mmoles C m−2 d−1) were observed in the "Green Belt" where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total NCP across the shelf was on the order of ~96 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning.

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What drives the latitudinal gradient in open-ocean surface dissolved inorganic carbon concentration?

Biogeosciences ◽

10.5194/bg-16-2661-2019 ◽

2019 ◽

Vol 16 (13) ◽

pp. 2661-2681 ◽

Cited By ~ 2

Author(s):

Yingxu Wu ◽

Mathis P. Hain ◽

Matthew P. Humphreys ◽

Sue Hartman ◽

Toby Tyrrell

Keyword(s):

Southern Ocean ◽

High Latitude ◽

Latitudinal Gradient ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Latitudinal Gradients ◽

Total Alkalinity ◽

Global Ocean ◽

Low Latitude ◽

Surface Ocean

Abstract. Previous work has not led to a clear understanding of the causes of spatial pattern in global surface ocean dissolved inorganic carbon (DIC), which generally increases polewards. Here, we revisit this question by investigating the drivers of observed latitudinal gradients in surface salinity-normalized DIC (nDIC) using the Global Ocean Data Analysis Project version 2 (GLODAPv2) database. We used the database to test three different hypotheses for the driver producing the observed increase in surface nDIC from low to high latitudes. These are (1) sea surface temperature, through its effect on the CO2 system equilibrium constants, (2) salinity-related total alkalinity (TA), and (3) high-latitude upwelling of DIC- and TA-rich deep waters. We find that temperature and upwelling are the two major drivers. TA effects generally oppose the observed gradient, except where higher values are introduced in upwelled waters. Temperature-driven effects explain the majority of the surface nDIC latitudinal gradient (182 of the 223 µmol kg−1 increase from the tropics to the high-latitude Southern Ocean). Upwelling, which has not previously been considered as a major driver, additionally drives a substantial latitudinal gradient. Its immediate impact, prior to any induced air–sea CO2 exchange, is to raise Southern Ocean nDIC by 220 µmol kg−1 above the average low-latitude value. However, this immediate effect is transitory. The long-term impact of upwelling (brought about by increasing TA), which would persist even if gas exchange were to return the surface ocean to the same CO2 as without upwelling, is to increase nDIC by 74 µmol kg−1 above the low-latitude average.

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Measurements of total alkalinity and inorganic dissolved carbon in the Atlantic Ocean and adjacent Southern Ocean between 2008 and 2010

Earth System Science Data Discussions ◽

10.5194/essdd-6-621-2013 ◽

2013 ◽

Vol 6 (2) ◽

pp. 621-639

Author(s):

U. Schuster ◽

A. J. Watson ◽

D. C. E. Bakker ◽

A. M. de Boer ◽

E. M. Jones ◽

...

Keyword(s):

Quality Control ◽

Atlantic Ocean ◽

Southern Ocean ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Drake Passage ◽

Total Alkalinity ◽

Global Ocean ◽

Atlantic Sector ◽

Dissolved Carbon

Abstract. Water column dissolved inorganic carbon and total alkalinity were measured during five hydrographic sections in the Atlantic Ocean and Drake Passage. The work was funded through the Strategic Funding Initiative of the UK's Oceans2025 programme, which ran from 2007 to 2012. The aims of this programme were to establish the regional budgets of natural and anthropogenic carbon in the North Atlantic, the South Atlantic, and the Atlantic sector of the Southern Ocean, as well as the rates of change of these budgets. This paper describes the dissolved inorganic carbon and total alkalinity data collected along east-west sections at 55–60° N (Arctic Gateway), 24.5° N, and 24° S in the Atlantic and across two Drake Passage sections. Other hydrographic and biogeochemical parameters were measured during these sections, yet are not covered in this paper. Over 95% of samples taken during the 24.5° N, 24° S, and the Drake Passage sections were analysed onboard and subjected to a 1st level quality control addressing technical and analytical issues. Samples taken during Arctic Gateway were analysed and subjected to quality control back in the laboratory. Complete post-cruise 2nd level quality control was performed using cross-over analysis with historical data in the vicinity of measurements, and data are available through the Carbon Dioxide Information Analysis Center (CDIAC) and are included in the Global Ocean Data Analyses Project, version 2 (GLODAP 2).

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Rising surface ocean dissolved inorganic carbon at the Hawaii Ocean Time-series site

Marine Chemistry ◽

10.1016/s0304-4203(97)00085-6 ◽

1998 ◽

Vol 60 (1-2) ◽

pp. 33-47 ◽

Cited By ~ 67

Author(s):

Christopher D. Winn ◽

Yuan-Hui Li ◽

Fred T. Mackenzie ◽

David M. Karl

Keyword(s):

Time Series ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Surface Ocean

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Utilizing the Drake Passage Time-series to understand variability and change in subpolar Southern Ocean pCO<sub>2</sub>

10.5194/bg-2017-489 ◽

2017 ◽

Cited By ~ 1

Author(s):

Amanda R. Fay ◽

Nicole S. Lovenduski ◽

Galen A. McKinley ◽

David R. Munro ◽

Colm Sweeney ◽

...

Keyword(s):

Time Series ◽

Southern Ocean ◽

Seasonal Cycle ◽

Drake Passage ◽

Passage Time ◽

Global Ocean ◽

Carbon Uptake ◽

Surface Ocean ◽

Ocean Carbon

Abstract. The Southern Ocean is highly under-sampled for the purpose of assessing total carbon uptake and its variability. Since this region dominates the mean global ocean sink for anthropogenic carbon, understanding temporal change is critical. Underway measurements of pCO2 collected as part of the Drake Passage Time-series (DPT) program that began in 2002 inform our understanding of seasonally changing air-sea gradients in pCO2, and by inference the carbon flux in this region. Here, we utilize all available pCO2 observations collected in the subpolar Southern Ocean to evaluate how the seasonal cycle, interannual variability, and long-term trends in surface ocean pCO2 in the Drake Passage region compare to that of the broader subpolar Southern Ocean. Our results indicate that the Drake Passage is representative of the broader region in both seasonality and long term pCO2 trends shown through the agreement of timing and amplitude of seasonal cycles as well as trend magnitudes. The high temporal density of sampling by the DPT is critical to constraining estimates of the seasonal cycle of surface pCO2 in this region, as winter data remain sparse in areas outside of the Drake Passage. From 2002–2015, data show that carbon uptake has strengthened with surface ocean pCO2 trends less than the global atmospheric trend in the Drake Passage and the broader subpolar Southern Ocean. Analysis of spatial correlation shows Drake Passage pCO2 to be representative of pCO2 and its variability up to several hundred kilometers upstream of the region. We also compare DPT data from 2016 and early 2017 to contemporaneous pCO2 estimates from autonomous biogeochemical floats deployed as part of the Southern Ocean Carbon and Climate Observations and Modeling project (SOCCOM) so as to highlight the opportunity for evaluating data collected on autonomous observational platforms. Though SOCCOM floats sparsely sample the Drake Passage region for 2016–2017, their pCO2 estimates typically fall within the range of underway observations. Going forward, continuation of the Drake Passage Time-series will reduce uncertainties in Southern Ocean carbon uptake seasonality, variability, and trends, and provide an invaluable independent dataset for post-deployment quality control of sensors on autonomous floats. Together, these datasets will vastly increase our ability to monitor change in the ocean carbon sink.

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Fluxes of carbon and nutrients to the Iceland Sea surface layer and inferred primary productivity and stoichiometry

Biogeosciences ◽

10.5194/bg-12-875-2015 ◽

2015 ◽

Vol 12 (3) ◽

pp. 875-885 ◽

Cited By ~ 4

Author(s):

E. Jeansson ◽

R. G. J. Bellerby ◽

I. Skjelvan ◽

H. Frigstad ◽

S. R. Ólafsdóttir ◽

...

Keyword(s):

Surface Layer ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Vertical Mixing ◽

Sea Surface ◽

Net Community Production ◽

Horizontal Advection ◽

Vertical Fluxes ◽

Community Production

Abstract. This study evaluates long-term mean fluxes of carbon and nutrients to the upper 100 m of the Iceland Sea. The study utilises hydro-chemical data from the Iceland Sea time series station (68.00° N, 12.67° W), for the years between 1993 and 2006. By comparing data of dissolved inorganic carbon (DIC) and nutrients in the surface layer (upper 100 m), and a sub-surface layer (100–200 m), we calculate monthly deficits in the surface, and use these to deduce the long-term mean surface layer fluxes that affect the deficits: vertical mixing, horizontal advection, air–sea exchange, and biological activity. The deficits show a clear seasonality with a minimum in winter, when the mixed layer is at the deepest, and a maximum in early autumn, when biological uptake has removed much of the nutrients. The annual vertical fluxes of DIC and nitrate amounts to 2.9 ± 0.5 and 0.45 ± 0.09 mol m−2 yr−1, respectively, and the annual air–sea uptake of atmospheric CO2 is 4.4 ± 1.1 mol C m−2 yr−1. The biologically driven changes in DIC during the year relates to net community production (NCP), and the net annual NCP corresponds to export production, and is here calculated as 7.3 ± 1.0 mol C m−2 yr−1. The typical, median C : N ratio during the period of net community uptake is 9.0, and clearly higher than the Redfield ratio, but is varying during the season.

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