scholarly journals Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

2015 ◽  
Vol 12 (11) ◽  
pp. 3153-3170 ◽  
Author(s):  
M. Rembauville ◽  
I. Salter ◽  
N. Leblond ◽  
A. Gueneugues ◽  
S. Blain
Keyword(s):  
Organic Carbon ◽  
Southern Ocean ◽  
Particulate Organic Carbon ◽  
Sediment Trap ◽  
Time Lag ◽  
Deep Ocean ◽  
Companion Paper ◽  
Grazing Pressure ◽  
Carbon Export ◽  
Poc Flux

Abstract. A sediment trap moored in the naturally iron-fertilized Kerguelen Plateau in the Southern Ocean provided an annual record of particulate organic carbon and nitrogen fluxes at 289 m. At the trap deployment depth, current speeds were typically low (~ 10 cm s−1) and primarily tidal-driven (M2 tidal component). Although advection was weak, the sediment trap may have been subject to hydrodynamical and biological (swimmer feeding on trap funnel) biases. Particulate organic carbon (POC) flux was generally low (< 0.5 mmol m−2 d−1), although two episodic export events (< 14 days) of 1.5 mmol m−2 d−1 were recorded. These increases in flux occurred with a 1-month time lag from peaks in surface chlorophyll and together accounted for approximately 40% of the annual flux budget. The annual POC flux of 98.2 ± 4.4 mmol m−2 yr−1 was low considering the shallow deployment depth but comparable to independent estimates made at similar depths (~ 300 m) over the plateau, and to deep-ocean (> 2 km) fluxes measured from similarly productive iron-fertilized blooms. Although undertrapping cannot be excluded in shallow moored sediment trap deployment, we hypothesize that grazing pressure, including mesozooplankton and mesopelagic fishes, may be responsible for the low POC flux beneath the base of the winter mixed layer. The importance of plankton community structure in controlling the temporal variability of export fluxes is addressed in a companion paper.

scholarly journals Export fluxes in a naturally fertilized area of the Southern Ocean, the Kerguelen Plateau: seasonal dynamic reveals long lags and strong attenuation of particulate organic carbon flux (Part 1)

2014 ◽  
Vol 11 (12) ◽  
pp. 17043-17087 ◽  
Author(s):  
M. Rembauville ◽  
I. Salter ◽  
N. Leblond ◽  
A. Gueneugues ◽  
S. Blain
Keyword(s):  
Organic Carbon ◽  
Southern Ocean ◽  
Particulate Organic Carbon ◽  
Sediment Trap ◽  
Time Lag ◽  
Deep Ocean ◽  
Biomass Accumulation ◽  
Companion Paper ◽  
Kerguelen Plateau ◽  
Poc Flux

Abstract. A sediment trap moored in the naturally iron-fertilized Kerguelen plateau in the Southern Ocean provided an annual record of particulate organic carbon and nitrogen fluxes at 289 m. At the trap deployment depth current speeds were low (∼10 cm s−1) and primarily tidal-driven (M2 tidal component) providing favorable hydrodynamic conditions for the collection of flux. Particulate organic carbon (POC) flux was generally low (<0.5 mmol m−2 d−1) although two episodic export events (<14 days) of 1.5 mmol m−2 d−1 were recorded. These increases in flux occurred with a 1 month time lag from peaks in surface chlorophyll and together accounted for approximately 40% of the annual flux budget. The annual POC flux of 98.2 ± 4.4 mmol m−2 yr−1 was relatively low considering the shallow deployment depth, but similar to deep-ocean (>2 km) fluxes measured from similarly productive iron-fertilized blooms. Comparison of the sediment trap data with complementary estimates of biomass accumulation and export indicate that ∼90% of the flux was lost between 200 and 300 m. We hypothesize that grazing pressure, including mesozooplankton and mesopelagic fishes, may be responsible for rapid flux attenuation and the High Biomass Low Export regime characterizing the Kerguelen bloom. The importance of plankton community structure in controlling the temporal variability of export fluxes is addressed in a companion paper.

scholarly journals Continuous moulting by Antarctic krill drives major pulses of carbon export in the north Scotia Sea, Southern Ocean

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Manno ◽  
S. Fielding ◽  
G. Stowasser ◽  
E. J. Murphy ◽  
S. E. Thorpe ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Antarctic Krill ◽  
Deep Ocean ◽  
Carbon Export ◽  
Scotia Sea ◽  
Faecal Pellets ◽  
The North ◽  
Poc Flux ◽  
Moulting Cycle

AbstractAntarctic krill play an important role in biogeochemical cycles and can potentially generate high-particulate organic carbon (POC) fluxes to the deep ocean. They also have an unusual trait of moulting continuously throughout their life-cycle. We determine the krill seasonal contribution to POC flux in terms of faecal pellets (FP), exuviae and carcasses from sediment trap samples collected in the Southern Ocean. We found that krill moulting generated an exuviae flux of similar order to that of FP, together accounting for 87% of an annual POC flux (22.8 g m−2 y−1). Using an inverse modelling approach, we determined the krill population size necessary to generate this flux peaked at 261 g m−2. This study shows the important role of krill exuviae as a vector for POC flux. Since krill moulting cycle depends on temperature, our results highlight the sensitivity of POC flux to rapid regional environmental change.

scholarly journals Carbon export and transfer to depth across the Southern Ocean Great Calcite Belt

2015 ◽  
Vol 12 (13) ◽  
pp. 3953-3971 ◽  
Author(s):  
S. Z. Rosengard ◽  
P. J. Lam ◽  
W. M. Balch ◽  
M. E. Auro ◽  
S. Pike ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Deep Ocean ◽  
Euphotic Zone ◽  
Biological Pump ◽  
Carbon Export ◽  
Mesopelagic Zone ◽  
Poc Flux ◽  
Phytoplankton Communities ◽  
Poc Export ◽  
Particulate Inorganic Carbon

Abstract. Sequestration of carbon by the marine biological pump depends on the processes that alter, remineralize, and preserve particulate organic carbon (POC) during transit to the deep ocean. Here, we present data collected from the Great Calcite Belt, a calcite-rich band across the Southern Ocean surface, to compare the transformation of POC in the euphotic and mesopelagic zones of the water column. The 234Th-derived export fluxes and size-fractionated concentrations of POC, particulate inorganic carbon (PIC), and biogenic silica (BSi) were measured from the upper 1000 m of 27 stations across the Atlantic and Indian sectors of the Great Calcite Belt. POC export out of the euphotic zone was correlated with BSi export. PIC export was not, but did correlate positively with POC flux transfer efficiency. Moreover, regions of high BSi concentrations, which corresponded to regions with proportionally larger particles, exhibited higher attenuation of > 51 μm POC concentrations in the mesopelagic zone. The interplay among POC size partitioning, mineral composition, and POC attenuation suggests a more fundamental driver of POC transfer through both depth regimes in the Great Calcite Belt. In particular, we argue that diatom-rich communities produce large and labile POC aggregates, which not only generate high export fluxes but also drive more remineralization in the mesopelagic zone. We observe the opposite in communities with smaller calcifying phytoplankton, such as coccolithophores. We hypothesize that these differences are influenced by inherent differences in the lability of POC exported by different phytoplankton communities.

scholarly journals Global Ocean Particulate Organic Carbon Flux Merged with Satellite Parameters

2016 ◽  
Author(s):  
Colleen B. Mouw ◽  
Audrey Barnett ◽  
Galen A. McKinley ◽  
Lucas Gloege ◽  
Darren Pilcher
Keyword(s):  
Time Series ◽  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Net Primary Production ◽  
Mixed Layer Depth ◽  
Deep Ocean ◽  
Euphotic Zone ◽  
Sediment Traps ◽  
Global Ocean ◽  
Carbon Export

Abstract. Particulate organic carbon (POC) flux estimated from POC concentration observations from sediment traps and 234Th are compiled across the global ocean. The compilation includes six time series locations: CARIACO, K2, OSP, BATS, OFP and HOT. Efficiency of the biological pump of carbon to the deep ocean depends largely on biologically mediated export of carbon from the surface ocean and its remineralization with depth, thus biologically related parameters able to be estimated from satellite observations were merged at the POC observation sites. Satellite parameters include: net primary production, percent microplankton, sea surface temperature, photosynthetically active radiation, diffuse attenuation coefficient at 490 nm, euphotic zone depth, as well as, climatological mixed layer depth. 85 % of the observations across the globe are concentrated in the Northern Hemisphere with 44 % of the data record overlapping the satellite record. Time series sites accounted for 36 % of the data. 71 % of the data is measured at ≥ 500 m with the most common deployment depths between 1000 and 1500 m. This dataset is valuable for investigations of CO2 drawdown, carbon export, remineralization, and sequestration. The compiled data can be freely accessed at doi:10.1594/PANGAEA.855600.

scholarly journals Carbon export and transfer to depth across the Southern Ocean Great Calcite Belt

2015 ◽  
Vol 12 (3) ◽  
pp. 2843-2896
Author(s):  
S. Z. Rosengard ◽  
P. J. Lam ◽  
W. M. Balch ◽  
M. E. Auro ◽  
S. Pike ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Deep Ocean ◽  
Euphotic Zone ◽  
Biological Pump ◽  
Carbon Export ◽  
Mesopelagic Zone ◽  
Poc Flux ◽  
Phytoplankton Communities ◽  
Poc Export ◽  
Particulate Inorganic Carbon

Abstract. Sequestration of carbon by the marine biological pump depends on the processes that alter, remineralize and preserve particulate organic carbon (POC) during transit to the deep ocean. Here, we present data collected from the Great Calcite Belt, a calcite-rich band across the Southern Ocean surface, to compare the transformation of POC in the euphotic and mesopelagic zones of the water column. The 234Th-derived export fluxes and size-fractionated concentrations of POC, particulate inorganic carbon (PIC), and biogenic silica (BSi) were measured from the upper 1000 m of 27 stations across the Atlantic and Indian sectors of the Great Calcite Belt. POC export out of the euphotic zone was correlated with BSi export. PIC export was not, but did correlate positively with POC flux transfer efficiency. Moreover, regions of high BSi concentrations, which corresponded to regions with proportionally larger particles, exhibited higher attenuation of >51 μm POC concentrations in the mesopelagic zone. The interplay among POC size partitioning, mineral composition and POC attenuation suggests a more fundamental driver of POC transfer through both depth regimes in the Great Calcite Belt. In particular, we argue that diatom-dominated communities produce large and labile POC aggregates, which generate high export fluxes but also drive more remineralization in the mesopelagic zone. We observe the opposite in communities with smaller calcifying phytoplankton, such as coccolithophores. We hypothesize that these differences are influenced by inherent differences in the lability of POC exported by different phytoplankton communities.

scholarly journals Variations in contributions of dead copepods to vertical fluxes of particulate organic carbon in the Beaufort Sea

2020 ◽  
Vol 642 ◽  
pp. 67-81
Author(s):  
M Sampei ◽  
A Forest ◽  
L Fortier ◽  
T Yamamoto ◽  
H Hattori ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Marine Ecosystem ◽  
Beaufort Sea ◽  
Sediment Traps ◽  
Regional Variability ◽  
Carbon Export ◽  
Vertical Fluxes ◽  
Poc Flux ◽  
Flux Variability

Dead zooplankton, including crustaceans, are increasingly recognized as important agents of vertical carbon export from surface waters and in marine food webs. Quantifying the contribution of passively sinking copepods (PSCs) to vertical fluxes of total particulate organic carbon (POC) is important for understanding marine ecosystem carbon budgets. Information on this is limited because identifying PSCs in sediment trap samples is difficult. Generally, swimmers (undecomposed metazoans, including PSCs, caught in sediment traps) are removed from a trap sample before the POC content is measured, although ignoring PSCs causes the total POC flux to be significantly underestimated. We quantified temporal and regional variability in PSC flux and contribution of PSCs to total POC flux (PSCs + detrital sinking particles, generally analyzed to estimate detrital POC flux) at the Mackenzie Shelf margins in the Beaufort Sea. Six datasets were used to examine PSC flux variability at ~100 m depth, which is deeper than the winter pycnocline depth (30-50 m), at the continental margin. The average (±SD) annual PSC flux (1378 ± 662 mg C m-2 yr-1, n = 6 [datasets]) and PSC contribution to the total POC flux (21 ± 10%, n = 6) suggested that PSCs, especially Pareuchaeta glacialis, were important agents of POC export from the surface layer (~100 m) to deeper water at the inter-regional and multiyear scales. We propose a hypothesis that processes controlling PSC flux variability may vary seasonally, perhaps relating to life cycle (reproduction) in winter (February) and osmotic stress in July-October when the PSC flux is relatively high.

scholarly journals Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean

2015 ◽  
Vol 112 (4) ◽  
pp. 1089-1094 ◽  
Author(s):  
Chris M. Marsay ◽  
Richard J. Sanders ◽  
Stephanie A. Henson ◽  
Katsiaryna Pabortsava ◽  
Eric P. Achterberg ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Atmospheric Carbon Dioxide ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Length Scale ◽  
Deep Sea Sediment ◽  
The North ◽  
Labile Fraction ◽  
Poc Flux

The biological carbon pump, which transports particulate organic carbon (POC) from the surface to the deep ocean, plays an important role in regulating atmospheric carbon dioxide (CO2) concentrations. We know very little about geographical variability in the remineralization depth of this sinking material and less about what controls such variability. Here we present previously unpublished profiles of mesopelagic POC flux derived from neutrally buoyant sediment traps deployed in the North Atlantic, from which we calculate the remineralization length scale for each site. Combining these results with corresponding data from the North Pacific, we show that the observed variability in attenuation of vertical POC flux can largely be explained by temperature, with shallower remineralization occurring in warmer waters. This is seemingly inconsistent with conclusions drawn from earlier analyses of deep-sea sediment trap and export flux data, which suggest lowest transfer efficiency at high latitudes. However, the two patterns can be reconciled by considering relatively intense remineralization of a labile fraction of material in warm waters, followed by efficient downward transfer of the remaining refractory fraction, while in cold environments, a larger labile fraction undergoes slower remineralization that continues over a longer length scale. Based on the observed relationship, future increases in ocean temperature will likely lead to shallower remineralization of POC and hence reduced storage of CO2 by the ocean.

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