scholarly journals The Sensitivity of Subsurface Microbes to Ocean Warming Accentuates Future Declines in Particulate Carbon Export

2019 ◽  
Vol 6 ◽  
Author(s):  
Emma Louise Cavan ◽  
Stephanie A. Henson ◽  
Philip W. Boyd
Keyword(s):  
Ocean Warming ◽  
Particulate Carbon ◽  
Carbon Export

scholarly journals Latitudinal distributions of particulate carbon export across the North Western Atlantic Ocean

2017 ◽  
Vol 129 ◽  
pp. 116-130 ◽  
Author(s):  
Viena Puigcorbé ◽  
Montserrat Roca-Martí ◽  
Pere Masqué ◽  
Claudia Benitez-Nelson ◽  
Michiel Rutgers van der Loeff ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Western Atlantic ◽  
Western Atlantic Ocean ◽  
The North ◽  
North Western

scholarly journals Zooplankton trophic dynamics drive carbon export efficiency

2021 ◽  
Author(s):  
Camila Serra-Pompei ◽  
Ben A. Ward ◽  
Jérôme Pinti ◽  
André W. Visser ◽  
Thomas Kiørboe ◽  
...  
Keyword(s):  
3D Model ◽  
Deep Ocean ◽  
Growth Efficiency ◽  
Size Spectrum ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Detrital Particles ◽  
Planktonic Community ◽  
Clear Relation ◽  
Spectrum Model

AbstractThe flux of detrital particles produced by plankton is an important component of the biological carbon pump. We investigate how food web structure and organisms’ size regulate particulate carbon export efficiency (the fraction of primary production that is exported via detrital particles at a given depth). We use the Nutrient-Unicellular-Multicellular (NUM) mechanistic size-spectrum model of the planktonic community (unicellular pro-tists and copepods), embedded within a 3D model representation of the global ocean circulation. The ecosystem model generates emergent food webs and size distributions of all organisms and detrital particles. Model outputs are compared to field data. We find that strong predation by copepods increases export efficiency, while protist predation reduces it. We find no clear relation between primary production and export efficiency. Temperature indirectly drives carbon export efficiency by affecting the biomass of copepods. High temperatures, combined with nutrient limitation, result in low growth efficiency, smaller trophic transfer to higher trophic levels, and decreased carbon export efficiency. Even though copepods consume a large fraction of the detritus produced, they do not markedly attenuate the particle flux. Our simulations illustrate the complex relation between the planktonic food web and export efficiency, and highlights the central role of zooplankton and their size structure.Plain Language SummaryPlankton are small organisms that live in the ocean. Plankton remove CO2 from the atmosphere by doing photosynthesis and sinking to the deep ocean, where the CO2 is sequestered. Photosynthesis can be measured by satellites, and therefore, knowing the fraction of photosynthesis that sinks to the deep ocean could allow making more accurate predictions of the concentration of CO2 in the atmosphere. This fraction of photosynthesis that is exported is termed “carbon export efficiency”. However, the drivers that define this carbon export efficiency are not well understood. To explore these drivers, we used computer simulations that include many planktonic organisms in a 3D model of the oceans. The model generates a detailed representation of the body sizes of plankton and of particle sizes, which is one of the main features defining sinking rates of particles in nature. We find that export efficiency is high when large zooplankton consume large amounts of prey. Temperature decreases export efficiency by reducing how efficient large plankton grow. Finally, we do not find a clear relation between photosynthesis and export efficiency, which has been much discussed in the literature. This provides mechanistic explanations to previous field observations and generates new hypotheses to be tested.Key Points:We used a 3D size-spectrum model of the planktonic community to understand the drivers of particulate carbon export efficiencyWe find that high temperature decreases growth efficiency, trophic transfer efficiency and associated carbon export efficiency.Systems that are top-down controlled by zooplankton can have high export efficiencies depending on the size of the dominant zooplankton.

scholarly journals High nitrate to phosphorus ratio attenuates negative effects of rising <i>p</i>CO<sub>2</sub> on net population carbon accumulation

2011 ◽  
Vol 8 (4) ◽  
pp. 6833-6857
Author(s):  
S. A. Krug ◽  
S. L. Eggers ◽  
B. Matthiessen
Keyword(s):  
Ocean Acidification ◽  
Population Level ◽  
N:P Ratio ◽  
Carbon Accumulation ◽  
Phosphate Limitation ◽  
Cell Physiology ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Population Response ◽  
Atmospheric Pco2

Abstract. The ongoing rise in atmospheric pCO2 and the consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton which potentially translates into altered carbon export. To date it remains unclear first, how nutrient ratio, in particular from coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation. Second, how direct physiological responses on the cellular level translate into a net population response. In this study cultures of Emiliania huxleyi were full-factorially exposed to two different N:P ratios (Redfield and high N:P) and three different pCO2 levels. Effects on net population particulate inorganic and organic carbon (PIC, POC) were measured after E. huxleyi cultures reached stationary phase. Thereby cell sizes and total cell abundance were taken into account. Corresponding to literature results show a significant negative cellular PIC and POC response which, however, was strongest under high N:P ratio. In contrast, net population PIC and POC accumulation was significantly attenuated under high N:P ratio. We suggest that less cellular nutrient accumulation allowed for higher cell abundances which compensated for the strong negative cellular PIC and POC response to pCO2 on the population level. Moreover, the design of this study also allowed following natural alteration of carbon chemistry through changing DIC and alkalinity. Our results suggest that at high initial pCO2 natural alteration of pCO2 during the experimental runtime was regulated by algal biomass. In contrast, at low initial pCO2 the PIC/POC ratio was responsible for changes in pCO2. Our results point to the fact that the physiological (i.e. cellular) PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore recommended to consider effects of nutrient limitation on cell physiology and translate these to net population carbon accumulation when predicting the influence of coccolithophores on both, the atmospheric pCO2 feedback and their function in carbon export mechanisms.

scholarly journals Carbon Export and Fate Beneath a Dynamic Upwelled Filament off the California Coast

2020 ◽  
Author(s):  
Hannah L. Bourne ◽  
James K. B. Bishop ◽  
Elizabeth J. Connors ◽  
Todd J. Wood
Keyword(s):  
Carbon Flux ◽  
California Current ◽  
Research Process ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Upwelled Water ◽  
Long Term Ecological Research ◽  
Vertical Variations ◽  
Flux Increase

Abstract. To understand the vertical variations of carbon fluxes in biologically productive waters, four autonomous Carbon Flux Explorers (CFEs) and ship-lowered CTD-interfaced particle-sensitive transmissometer and scattering sensors were deployed in a filament of offshore flowing recently upwelled water during the June 2017 California Current Ecosystem – Long Term Ecological Research process study. The Lagrangian CFEs operating at depths from 100–500 m yielded carbon flux and its partitioning with size from 30 µm–1 cm at three intense study locations within the filament and at a location outside the filament. Different particle classes (anchovy pellets, copepod pellets and > 1000 µm aggregates) dominated the 100–150 m fluxes during successive stages of the filament evolution as it progressed offshore. Fluxes were very high at all locations in the filament; below 150 m, flux was invariant or increased with depth at the two locations closer to the coast. Martin curve b factors for total particulate carbon flux were +0.1, +0.87, −0.27, and −0.39 at the three successively occupied locations within the plume, and in transitional waters, respectively. Particle transfer efficiencies between 100 to 500 m were far greater within both filament and California Current waters than calculated using a classic Martin b factor of −0.86. Interestingly, the flux profiles for all particles  90 %) of particle flux was carried by > 1000 µm sized aggregates. Mechanisms to explain a factor of three flux increase between 150 and 500 m at the mid plume location are investigated.

scholarly journals Variations in the abundance and distribution of aggregates in the Ross Sea, Antarctica

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Vernon L. Asper ◽  
Walker O. Smith
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Ross Sea ◽  
Late Summer ◽  
Early Summer ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Phaeocystis Antarctica ◽  
Abundance And Distribution ◽  
The Vertical Distribution

The vertical distribution and temporal changes in aggregate abundance and sizes were measured in the Ross Sea, Antarctica between 2002 and 2005 to acquire a more complete understanding of the mechanisms and rates of carbon export from the euphotic layer. Aggregate abundance was determined by photographic techniques, and water column parameters (temperature, salinity, fluorescence, transmissometry) were assessed from CTD profiles. During the first three years the numbers of aggregates increased seasonally, being much more abundant within the upper 200 m in late summer than in early summer from 50 to 100 m (12.5 L–1 in early summer vs. 42.9 L–1 in late summer). In Year 4 aggregate numbers were substantially greater than in other years, and average aggregate abundance was maximal in early rather than late summer (177 vs. 84.5 L–1), which we attributed to the maximum biomass and aggregate formation being reached earlier than in other years. The contribution of aggregate particulate organic carbon to the total particulate carbon pool was estimated to be 20%. Ghost colonies, collapsed colonies of the haptophyte Phaeocystis antarctica, were observed during late summer in Year 4, with maximum numbers in the upper 100 m of ca. 40 L–1. Aggregate abundance, particulate organic carbon and ghost colonies all decreased exponentially with depth, and the rate of ghost colony disappearance suggested that their contribution to sedimentary input was small at the time of sampling. Bottom nepheloid layers were commonly observed in late summer in both transmissometer and aggregate data. Late summer nepheloid layers had fluorescent material within them, suggesting that the particles were likely generated during the same growing season. Longer studies encompassing the entire production season would be useful in further elucidating the role of these aggregates in the carbon cycle of these regions.

scholarly journals Microbial dynamics of elevated carbon flux in the open ocean’s abyss

2021 ◽  
Vol 118 (4) ◽  
pp. e2018269118
Author(s):  
Kirsten E. Poff ◽  
Andy O. Leu ◽  
John M. Eppley ◽  
David M. Karl ◽  
Edward F. DeLong
Keyword(s):  
Deep Sea ◽  
Carbon Flux ◽  
Particle Formation ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Sinking Particles ◽  
Attached Bacteria ◽  
Deep Sea Bacteria ◽  
Diazotrophic Cyanobacteria ◽  
Aerobic Anoxygenic Photosynthesis

In the open ocean, elevated carbon flux (ECF) events increase the delivery of particulate carbon from surface waters to the seafloor by severalfold compared to other times of year. Since microbes play central roles in primary production and sinking particle formation, they contribute greatly to carbon export to the deep sea. Few studies, however, have quantitatively linked ECF events with the specific microbial assemblages that drive them. Here, we identify key microbial taxa and functional traits on deep-sea sinking particles that correlate positively with ECF events. Microbes enriched on sinking particles in summer ECF events included symbiotic and free-living diazotrophic cyanobacteria, rhizosolenid diatoms, phototrophic and heterotrophic protists, and photoheterotrophic and copiotrophic bacteria. Particle-attached bacteria reaching the abyss during summer ECF events encoded metabolic pathways reflecting their surface water origins, including oxygenic and aerobic anoxygenic photosynthesis, nitrogen fixation, and proteorhodopsin-based photoheterotrophy. The abundances of some deep-sea bacteria also correlated positively with summer ECF events, suggesting rapid bathypelagic responses to elevated organic matter inputs. Biota enriched on sinking particles during a spring ECF event were distinct from those found in summer, and included rhizaria, copepods, fungi, and different bacterial taxa. At other times over our 3-y study, mid- and deep-water particle colonization, predation, degradation, and repackaging (by deep-sea bacteria, protists, and animals) appeared to shape the biotic composition of particles reaching the abyss. Our analyses reveal key microbial players and biological processes involved in particle formation, rapid export, and consumption, that may influence the ocean’s biological pump and help sustain deep-sea ecosystems.

scholarly journals Deep silicon maxima in the stratified oligotrophic Mediterranean Sea

2010 ◽  
Vol 7 (5) ◽  
pp. 6789-6846 ◽  
Author(s):  
Y. Crombet ◽  
K. Leblanc ◽  
B. Quéguiner ◽  
T. Moutin ◽  
P. Rimmelin ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
Particulate Carbon ◽  
Carbon Export ◽  
Common View ◽  
Centric Diatoms ◽  
Levantine Basin ◽  
The Common ◽  
The Mediterranean ◽  
Marine Productivity

Abstract. The silicon biogeochemical cycle has been studied in the Mediterranean Sea during fall 1999 and summer 2008. The distribution of nutrients, particulate carbon and silicon, fucoxanthin (Fuco) and total chlorophyll-a (Tchl-a) were investigated along an eastward gradient of oligotrophy during two cruises (PROSOPE and BOUM) encompassing the entire Mediterranean Sea during the stratified period. At both seasons, surface waters were depleted in nutrients and the nutriclines gradually deepened towards the East, the phosphacline being the deepest in the easternmost Levantine basin. Following the nutriclines, correlated deep maxima of biogenic silica (DSM), fucoxanthin (DFM) and Tchl-a (DCM) were evidenced during both seasons with maximal concentrations of 0.45 μmol L−1 for BSi, 0.26 μg L−1 for Fuco, and 1.70 μg L−1 for Tchl-a, all measured during summer. Contrary to the DCM which was a persistent feature in the Mediterranean Sea, the DSM and DFMs were observed in discrete areas of the Alboran Sea, the Algero-Provencal basin, the Ionian sea and the Levantine basin, indicating that diatoms were able to grow at depth and dominate the DCM under specific conditions. Diatom assemblages were dominated by Chaetoceros spp., Leptocylindrus spp., Pseudonitzschia spp. and the association between large centric diatoms (Hemiaulus hauckii and Rhizosolenia styliformis) and the cyanobacterium Richelia intracellularis was observed at nearly all sites. The diatom's ability to grow at depth is commonly observed in other oligotrophic regions and could play a major role in ecosystem productivity and carbon export to depth. Contrary to the common view that Si and siliceous phytoplankton are not major components of the Mediterranean biogeochemistry, we suggest here that diatoms, by persisting at depth during the stratified period, could contribute to a large part to the marine productivity and biological pump, as observed in other oligotrophic areas.

Dissolved and particulate carbon export from a tropical mangrove‐dominated riverine system

2021 ◽  
Author(s):  
Raghab Ray ◽  
Toshihiro Miyajima ◽  
Atsushi Watanabe ◽  
Masaya Yoshikai ◽  
Charissa M. Ferrera ◽  
...  
Keyword(s):  
Particulate Carbon ◽  
Carbon Export
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