Rate and fate of dissolved organic carbon release by seaweeds: a missing link in the coastal ocean carbon cycle

2021 ◽  
Author(s):  
Ellie R. Paine ◽  
Matthias Schmid ◽  
Philip W. Boyd ◽  
Guillermo Diaz‐Pulido ◽  
Catriona L. Hurd
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Dissolved Organic Carbon ◽  
Coastal Ocean ◽  
Ocean Carbon Cycle ◽  
Missing Link ◽  
Carbon Release ◽  
Ocean Carbon

Past century increases of terrestrial nutrient inputs impact both the coastal and open ocean carbon cycle

2021 ◽  
Author(s):  
Fabrice Lacroix ◽  
Tatiana Ilyina ◽  
Moritz Mathis ◽  
Goulven Gildas Laruelle ◽  
Pierre Regnier
Keyword(s):  
Carbon Cycle ◽  
Coastal Ocean ◽  
Open Ocean ◽  
Time Span ◽  
Ocean Dynamics ◽  
Global Ocean ◽  
Past Century ◽  
Nutrient Inputs ◽  
Ocean Carbon Cycle ◽  
Ocean Carbon

<p>Past century increases in terrigenous N and P inputs to the ocean due to industrialization, agricultural practices and wastewater have been reported to have dramatic consequences for ecosystems in various coastal regions. Yet, the impacts of increased nutrient inputs through river transports and atmospheric deposition on the coastal and open ocean carbon cycle have yet to be quantitatively investigated at the global scale. To address this gap of knowledge, we enhanced the ocean biogeochemical model HAMOCC at a horizontal resolution of around 0.4° in order to improve the representation of temporal changes of riverine fluxes and of coastal ocean dynamics in the model. Through a series of simulations with differing model forcings, we isolated individual effects arising from (1) increasing atmospheric CO<sub>2</sub> levels, (2) a changing physical climate and (3) alterations in oceanic inputs of terrigenous P and N inputs, all over the 1905 to 2010 period. Our results indicate a strong response of the coastal ocean ecosystem to increased terrestrial nutrient inputs, which induce the global coastal Net Primary Production (NPP) to increase by 14% over the simulation time span. This eutrophication signal is, furthermore, partly exported to the open ocean, which undergoes an increase in NPP of 1.75 Pg C yr<sup>-1</sup>, or 4 % in relative terms, in the simulations, owing to the cross-shelf export of 33-46% of the anthropogenic P and N inputs to the coastal ocean. As a whole, increased P and N inputs lead to an overall global ocean NPP rise of around 2.15 Pg C yr<sup>-1</sup>, or 5% (combined coastal and open ocean). This net increase attributed to land-ocean couplings exceeds the simulated global oceanic NPP decrease of 4 % associated with stronger upper ocean thermal stratification over the time span, a feedback that been under stronger scrutiny in published literature. Our results suggest that increased riverine nutrient concentrations due to anthropogenic activities may also have substantial impacts for ecosystems in the open ocean, in contrary to what was assumed until now, although this is dependent on the rate of transfer of the nutrients from the coastal to the open ocean.</p>

scholarly journals Changes in the Arctic Ocean carbon cycle with diminishing ice cover

2020 ◽  
Author(s):  
Michael D. DeGrandpre ◽  
Wiley Evans ◽  
Mary-Louise Timmermans ◽  
Richard A. Krishfield ◽  
William J Williams ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Arctic Ocean ◽  
Ice Cover ◽  
The Arctic ◽  
Ocean Carbon Cycle ◽  
The Arctic Ocean ◽  
Ocean Carbon

scholarly journals A fishy tale: A missing part of the inorganic ocean carbon cycle

2011 ◽  
Vol 33 (3) ◽  
pp. 30-34
Author(s):  
Rod W. Wilson ◽  
Erin E. Reardon ◽  
Christopher T. Perry
Keyword(s):  
Carbon Cycle ◽  
Ocean Acidification ◽  
Fossil Fuels ◽  
Sea Water ◽  
Atmospheric Co2 ◽  
Co2 Production ◽  
Ph Change ◽  
Ocean Carbon Cycle ◽  
Sea Levels ◽  
Ocean Carbon

Human activities, such as burning fossil fuels, are playing an important role in the rising levels of carbon dioxide (CO2) in the Earth's atmosphere1. The oceans may store a large portion of CO2 that we are releasing into the atmosphere, with up to 40% already taken up by the oceans. Although this absorption helps to offset some of the greenhouse effect of atmospheric CO2, it also contributes to ocean acidification, or a fall in the pH of sea water. The historical global mean pH of oceanic sea water is about 8.2, and this has already declined by 0.1 pH units (a 30% increase in H+ concentration) and is predicted to reach pH ~7.7 by the end of the century if current rates of fossil fuel use continue, leading to an atmospheric CO2 level of 800 p.p.m.1,2. Even this extreme potential fall in pH would still leave seawater above the neutral point (pH 7.0), so technically it is more accurate to say that the ocean is becoming less alkaline, rather than truly acidic (i.e. below pH 7.0). However, the magnitude is perhaps less important than the speed of pH change which is occurring faster than at any time during the previous 20 million years. Over this time, the average ocean pH has probably never fallen below pH 8.02,3. It is only during the last decade that the importance of ocean acidification has come to the forefront of concerns for scientists1,2. Consequences of these changes in global CO2 production are predicted to include elevated global temperatures, rising sea levels, more unpredictable and extreme weather patterns, and shifts in ecosystems1. In order to more fully understand the implications of ocean acidification, teams of researchers, including fisheries scientists, physiologists, geologists, oceanographers, chemists and climate modellers, are working to refine current understanding of the ocean carbon cycle.

scholarly journals Characterization of bacterioplankton communities and quantification of organic carbon pools off the Galapagos Archipelago under contrasting environmental conditions

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5984 ◽  
Author(s):  
Nataly Carolina Guevara Campoverde ◽  
Christiane Hassenrück ◽  
Pier Luigi Buttigieg ◽  
Astrid Gärdes
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Dissolved Organic Carbon ◽  
Bacterial Communities ◽  
Carbon Pools ◽  
Aggregate Formation ◽  
Galapagos Archipelago ◽  
Carbon Concentrations ◽  
Bacterioplankton Communities

Bacteria play a crucial role in the marine carbon cycle, contributing to the production and degradation of organic carbon. Here, we investigated organic carbon pools, aggregate formation, and bacterioplankton communities in three contrasting oceanographic settings in the Galapagos Archipelago. We studied a submarine CO2 vent at Roca Redonda (RoR), an upwelling site at Bolivar Channel (BoC) subjected to a weak El Niño event at the time of sampling in October 2014, as well as a site without volcanic or upwelling influence at Cowley Islet (CoI). We recorded physico-chemical parameters, and quantified particulate and dissolved organic carbon, transparent exopolymeric particles, and the potential of the water to form larger marine aggregates. Free-living and particle-attached bacterial communities were assessed via 16S rRNA gene sequencing. Both RoR and BoC exhibited temperatures elevated by 1–1.5 °C compared to CoI. RoR further experienced reduced pH between 6.8 and 7.4. We observed pronounced differences in organic carbon pools at each of the three sites, with highest dissolved organic carbon concentrations at BoC and RoR, and highest particulate organic carbon concentrations and aggregate formation at BoC. Bacterioplankton communities at BoC were dominated by opportunistic copiotrophic taxa, such as Alteromonas and Roseobacter, known to thrive in phytoplankton blooms, as opposed to oligotrophic taxa dominating at CoI, such as members of the SAR11 clade. Therefore, we propose that bacterial communities were mainly influenced by the availability of organic carbon at the investigated sites. Our study provides a comprehensive characterization of organic carbon pools and bacterioplankton communities, highlighting the high heterogeneity of various components of the marine carbon cycle around the Galapagos Archipelago.

Coccolith chemistry reveals secular variations in the global ocean carbon cycle?

2007 ◽  
Vol 253 (1-2) ◽  
pp. 83-95 ◽  
Author(s):  
R.E.M. Rickaby ◽  
E. Bard ◽  
C. Sonzogni ◽  
F. Rostek ◽  
L. Beaufort ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Global Ocean ◽  
Ocean Carbon Cycle ◽  
Secular Variations ◽  
Ocean Carbon

scholarly journals Ocean Carbon Cycle Feedbacks Under Negative Emissions

2018 ◽  
Vol 45 (10) ◽  
pp. 5062-5070 ◽  
Author(s):  
Jörg Schwinger ◽  
Jerry Tjiputra
Keyword(s):  
Carbon Cycle ◽  
Ocean Carbon Cycle ◽  
Negative Emissions ◽  
Ocean Carbon
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