scholarly journals Global Carbon Cycling on a Heterogeneous Seafloor

2018 ◽  
Vol 33 (2) ◽  
pp. 96-105 ◽  
Author(s):  
Paul V.R. Snelgrove ◽  
Karline Soetaert ◽  
Martin Solan ◽  
Simon Thrush ◽  
Chih-Lin Wei ◽  
...  
Keyword(s):  
Carbon Cycling ◽  
Global Carbon

scholarly journals High and specific diversity of protists in the deep-sea basins dominated by diplonemids, kinetoplastids, ciliates and foraminiferans

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alexandra Schoenle ◽  
Manon Hohlfeld ◽  
Karoline Hermanns ◽  
Frédéric Mahé ◽  
Colomban de Vargas ◽  
...  
Keyword(s):  
Carbon Cycling ◽  
Deep Sea ◽  
Trophic Levels ◽  
Earth System ◽  
Parasitic Species ◽  
Unicellular Eukaryotes ◽  
The Earth ◽  
Dna Metabarcoding ◽  
Global Carbon ◽  
Pelagic Communities

AbstractHeterotrophic protists (unicellular eukaryotes) form a major link from bacteria and algae to higher trophic levels in the sunlit ocean. Their role on the deep seafloor, however, is only fragmentarily understood, despite their potential key function for global carbon cycling. Using the approach of combined DNA metabarcoding and cultivation-based surveys of 11 deep-sea regions, we show that protist communities, mostly overlooked in current deep-sea foodweb models, are highly specific, locally diverse and have little overlap to pelagic communities. Besides traditionally considered foraminiferans, tiny protists including diplonemids, kinetoplastids and ciliates were genetically highly diverse considerably exceeding the diversity of metazoans. Deep-sea protists, including many parasitic species, represent thus one of the most diverse biodiversity compartments of the Earth system, forming an essential link to metazoans.

scholarly journals High Rates of Ecosytem Metabolism in Five Western Rivers

2011 ◽  
Vol 33 ◽  
pp. 115-118
Author(s):  
Robert Hall ◽  
Jennifer Tank ◽  
Michelle Baker ◽  
Emma Rosi-Marshall ◽  
Michael Grace ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Carbon Cycling ◽  
Carbon Balance ◽  
Carbon Fixation ◽  
Higher Plants ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Total Rate ◽  
Global Carbon

Primary production and respiration are core functions of river ecosystems that in part determine the carbon balance. Gross primary production (GPP) is the total rate of carbon fixation by autotrophs such as algae and higher plants and is equivalent to photosynthesis. Ecosystem respiration (ER) measures rate at which organic carbon is mineralized to CO2 by all organisms in an ecosystem. Together these fluxes can indicate the base of the food web to support animal production (Marcarelli et al. 2011), can predict the cycling of other elements (Hall and Tank 2003), and can link ecosystems to global carbon cycling (Cole et al. 2007).

scholarly journals Phytoplankton calcifiers control nitrate cycling and the pace of transition in warming icehouse and cooling greenhouse climates

2019 ◽  
Vol 16 (5) ◽  
pp. 1019-1034 ◽  
Author(s):  
Karin F. Kvale ◽  
Katherine E. Turner ◽  
Angela Landolfi ◽  
Katrin J. Meissner
Keyword(s):  
Carbon Cycling ◽  
Net Primary Production ◽  
Global Ocean ◽  
Type Model ◽  
Nitrate Sources ◽  
Surface Temperature Change ◽  
Sources And Sinks ◽  
Greenhouse Climate ◽  
Small Phytoplankton ◽  
Global Carbon

Abstract. Phytoplankton calcifiers contribute to global carbon cycling through their dual formation of calcium carbonate and particulate organic carbon (POC). The carbonate might provide an efficient export pathway for the associated POC to the deep ocean, reducing the particles' exposure to biological degradation in the upper ocean and increasing the particle settling rate. Previous work has suggested ballasting of POC by carbonate might increase in a warming climate, in spite of increasing carbonate dissolution rates, because calcifiers benefit from the widespread nutrient limitation arising from stratification. We compare the biogeochemical responses of three models containing (1) a single mixed phytoplankton class, (2) additional explicit small phytoplankton and calcifiers, and (3) additional explicit small phytoplankton and calcifiers with a prognostic carbonate ballast model, to two rapid changes in atmospheric CO2. The first CO2 scenario represents a rapid (151-year) transition from a stable icehouse climate (283.9 ppm) into a greenhouse climate (1263 ppm); the second represents a symmetric rapid transition from a stable greenhouse climate into an icehouse climate. We identify a slope change in the global net primary production response with a transition point at about 3.5 ∘C global mean sea surface temperature change in all models, driven by a combination of physical and biological changes. We also find that in both warming and cooling scenarios, the application of a prognostic carbonate ballast model moderates changes in carbon export production, suboxic volume, and nitrate sources and sinks, reducing the long-term model response to about one-third that of the calcifier model without ballast. Explicit small phytoplankton and calcifiers, and carbonate ballasting, increase the physical separation of nitrate sources and sinks through a combination of phytoplankton competition and lengthened remineralization profile, resulting in a significantly higher global nitrate inventory in this model compared to the single phytoplankton type model (15 % and 32 % higher for icehouse and greenhouse climates). Higher nitrate inventory alleviates nitrate limitation, increasing phytoplankton sensitivity to changes in physical limitation factors (light and temperature). This larger sensitivity to physical forcing produces stronger shifts in ocean phosphate storage between icehouse and greenhouse climates. The greenhouse climate is found to hold phosphate and nitrate deeper in the ocean, despite a shorter remineralization length scale than the icehouse climate, because of the longer residence times of the deep water masses. We conclude the global biogeochemical impact of calcifiers extends beyond their role in global carbon cycling, and that the ecological composition of the global ocean can affect how ocean biogeochemistry responds to climate forcing.

scholarly journals Ocean acidification compromises a planktic calcifier with implications for global carbon cycling

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Catherine V. Davis ◽  
Emily B. Rivest ◽  
Tessa M. Hill ◽  
Brian Gaylord ◽  
Ann D. Russell ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Carbon Cycling ◽  
Global Carbon

scholarly journals Glacial heterogeneity in Southern Ocean carbon storage abated by fast South Indian deglacial carbon release

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Julia Gottschalk ◽  
Elisabeth Michel ◽  
Lena M. Thöle ◽  
Anja S. Studer ◽  
Adam P. Hasenfratz ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Carbon Cycling ◽  
Deep Ocean ◽  
The South ◽  
South Indian ◽  
Carbon Release ◽  
History Of ◽  
Ocean Carbon ◽  
History Of The South ◽  
Global Carbon

AbstractPast changes in ocean 14C disequilibria have been suggested to reflect the Southern Ocean control on global exogenic carbon cycling. Yet, the volumetric extent of the glacial carbon pool and the deglacial mechanisms contributing to release remineralized carbon, particularly from regions with enhanced mixing today, remain insufficiently constrained. Here, we reconstruct the deglacial ventilation history of the South Indian upwelling hotspot near Kerguelen Island, using high-resolution 14C-dating of smaller-than-conventional foraminiferal samples and multi-proxy deep-ocean oxygen estimates. We find marked regional differences in Southern Ocean overturning with distinct South Indian fingerprints on (early de-)glacial atmospheric CO2 change. The dissipation of this heterogeneity commenced 14.6 kyr ago, signaling the onset of modern-like, strong South Indian Ocean upwelling, likely promoted by rejuvenated Atlantic overturning. Our findings highlight the South Indian Ocean’s capacity to influence atmospheric CO2 levels and amplify the impacts of inter-hemispheric climate variability on global carbon cycling within centuries and millennia.

Anomalies in global carbon cycling and extinction at the Triassic/Jurassic boundary: evidence from a marine C-isotope record

2005 ◽  
Vol 216 (3-4) ◽  
pp. 203-214 ◽  
Author(s):  
Maria Teresa Galli ◽  
Flavio Jadoul ◽  
Stefano M. Bernasconi ◽  
Helmut Weissert
Keyword(s):  
Carbon Cycling ◽  
Isotope Record ◽  
Global Carbon

scholarly journals Phytoplankton calcifiers control nitrate cycling and the pace of transition in warming icehouse and cooling greenhouse climates

2018 ◽  
Author(s):  
Karin F. Kvale ◽  
Katherine E. Turner ◽  
Angela Landolfi ◽  
Katrin J. Meissner
Keyword(s):  
Carbon Cycling ◽  
Net Primary Production ◽  
Global Ocean ◽  
Type Model ◽  
Nitrate Sources ◽  
Surface Temperature Change ◽  
Sources And Sinks ◽  
Greenhouse Climate ◽  
Small Phytoplankton ◽  
Global Carbon

Abstract. Phytoplankton calcifiers contribute to global carbon cycling through their dual formation of calcium carbonate and particulate organic carbon (POC). The carbonate might provide an efficient export pathway for the associated POC to the deep ocean, reducing the particles' exposure to biological degradation in the upper ocean and increasing the particle settling rate. Previous work has suggested ballasting of POC by carbonate might increase in a warming climate, in spite of increasing carbonate dissolution rates, because calcifiers benefit from the widespread nutrient limitation arising from stratification. We compare the biogeochemical responses of three models containing 1) a single mixed phytoplankton class, 2) additional explicit small phytoplankton and calcifiers, and 3) additional explicit small phytoplankton and calcifiers with a prognostic carbonate ballast model, to two rapid changes in atmospheric CO2. The first CO2 scenario represents a rapid (150 year) transition from a stable icehouse climate (285 ppm) into a greenhouse climate (1257 ppm); the second represents a symmetric rapid transition from a stable greenhouse climate into an icehouse climate. We identify a slope change in the global net primary production response with a transition point at about 3.5 °C global mean sea surface temperature change in all models, driven by a combination of physics and biology. We also find that in both warming and cooling scenarios, the application of a prognostic carbonate ballast model moderates changes in carbon export production, suboxic volume, and nitrate sources and sinks, reducing the long-term model response to about one-third that of the calcifier model without ballast. Explicit small phytoplankton and calcifiers, and carbonate ballasting, increase the physical separation of nitrate sources and sinks through a combination of phytoplankton competition and lengthened remineralization profile, resulting in a significantly higher global nitrate inventory in this model compared to the single phytoplankton type model (15 % and 32 % higher, for icehouse and greenhouse climates). Higher nitrate inventory alleviates nitrate limitation, increasing phytoplankton sensitivity to changes in physical limitation factors (light and temperature). This larger sensitivity to physical forcing produces stronger shifts in ocean phosphate storage between icehouse and greenhouse climates. The greenhouse climate is found to hold phosphate and nitrate deeper in the ocean, despite a shorter remineralization length scale than the icehouse climate, because of the longer residence times of the deep water masses. We conclude the global biogeochemical impact of calcifiers extends beyond their role in global carbon cycling, and that the ecological composition of the global ocean can affect how ocean biogeochemistry responds to climate forcing.

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