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Seawater carbonate chemistry and biometry and dissolution features of the benthic foraminifer Ammonia aomoriensis in a laboratory experiment

Culturing experiments were performed with the benthic foraminifer Ammonia aomoriensis from Flensburg Fjord, western Baltic Sea. The experiments simulated a projected rise in atmospheric CO2 concentrations. We exposed specimens to 5 seawater pCO2 levels ranging from 618 µatm (pH 7.9) to 3130 µatm (pH 7.2) for 6 wk. Growth rates and mortality differed significantly among pCO2 treatments. The highest increase of mean test diameter (19%) was observed at 618 µatm. At partial pressures >1829 µatm, the mean test diameter was observed to decrease, by up to 22% at 3130 µatm. At pCO2 levels of 618 and 751 µatm, A. aomoriensis tests were found intact after the experiment. The outer chambers of specimens incubated at 929 and 1829 µatm were severely damaged by corrosion. Visual inspection of specimens incubated at 3130 µatm revealed wall dissolution of all outer chambers, only their inner organic lining stayed intact. Our results demonstrate that pCO2 values of >=929 µatm in Baltic Sea waters cause reduced growth of A. aomoriensis and lead to shell dissolution. The bottom waters in Flensburg Fjord and adjacent areas regularly experience pCO2 levels in this range during summer and fall. Increasing atmospheric CO2 concentrations are likely to extend and intensify these periods of undersaturation. This may eventually slow down calcification in A. aomoriensis to the extent that net carbonate precipitation terminates. The possible disappearance of this species from the Baltic Sea and other areas prone to seasonal undersaturation would likely cause significant shifts in shallow-water benthic ecosystems in the near future.

Seawater carbonate chemistry and benthic foraminifera Ammonia sp. uranium incorporation during experiments, 2013

The chemical and isotopic composition of foraminiferal shells (so-called proxies) reflects the physico-chemical properties of the seawater. In current day paleoclimate research, the reconstruction of past seawater carbonate system to infer atmospheric CO2 concentrations is one of the most pressing challenges and a variety of proxies have been investigated, such as foraminiferal U/Ca. Since in natural seawater and traditional CO2 perturbation experiments, the carbonate system parameters co-vary, it is not possible to determine the parameter of the carbonate system causing e.g. changes in U/Ca, complicating the use of the latter as a carbonate system proxy. We overcome this problem, by culturing the benthic foraminifer Ammonia sp. at a range of carbonate chemistry manipulation treatments. Shell U/Ca values were determined to test sensitivity of U incorporation to various parameters of the carbonate system. We argue that CO3 is the parameter affecting the U/Ca ratio and consequently, the partitioning coefficient for U in Ammonia sp DU. We can confirm the strong potential of foraminiferal U/Ca as a CO3 proxy.

CO2-Entnahme durch Alkalinitätserhöhung - Potenzial, Nutzen und Risiken, Vorhaben: Fischereimanagement unter Unsicherheit

WP2.2: Rückwirkungen der marinen Biogeochemie auf Klima und atmosphärisches CO2 - die Rolle von Zirkulation, Biologie, Sedimentation - Effekte des Absinkens von partikulärem Material im deglazialen und anthropogenen Klimawandel

ANK-MK: Brauntange (Laminaria ssp.) als Blue Carbon- Kohlenstoffspeicher bei Helgoland

Atmospheric methane and carbon dioxide concentrations measured during ALKOR cruise AL575 on 2022-06-30

Atmospheric carbon dioxide (CO2) and methane (CH4) concentrations were monitored during AL575 cruise on 2022-06-30 using a cavity ring down spectrometer (Picarro G2301-f CRDS) and GEOMARs 'Atmospheric Intake System' (AIS). The Picarro/AIS system was installed in the wet laboratory (starboard, main deck) of RV ALKOR and was connected by an aluminium tube to an air inlet nozzle placed at the bow of RV ALKOR. The air was pumped via the AIS intake tube with a flow rate of 2.67 litre per minute to the Picarro analyser. The atmospheric CH4, CO2, and water vapour concentrations were determined in real time at 2-3 Hz sampling rate. A time offset of 87 seconds between the air intake nozzle at the bow (6 m above sea surface) and the actual gas measurement at the Picarro was determined and the calculated flow rate considered, when correlating the gas data with navigation and weather data provided by the WERUM dship repository (https://dship.geomar.de). The weather data is published separately at doi:10.1594/PANGAEA.983833 .

Atmospheric methane and carbon dioxide concentrations measured during ALKOR cruise AL575 on 2022-07-11

Atmospheric carbon dioxide (CO2) and methane (CH4) concentrations were monitored during AL575 cruise on 2022-07-11 using a cavity ring down spectrometer (Picarro G2301-f CRDS) and GEOMARs 'Atmospheric Intake System' (AIS). The Picarro/AIS system was installed in the wet laboratory (starboard, main deck) of RV ALKOR and was connected by an aluminium tube to an air inlet nozzle placed at the bow of RV ALKOR. The air was pumped via the AIS intake tube with a flow rate of 2.67 litre per minute to the Picarro analyser. The atmospheric CH4, CO2, and water vapour concentrations were determined in real time at 2-3 Hz sampling rate. A time offset of 87 seconds between the air intake nozzle at the bow (6 m above sea surface) and the actual gas measurement at the Picarro was determined and the calculated flow rate considered, when correlating the gas data with navigation and weather data provided by the WERUM dship repository (https://dship.geomar.de). The weather data is published separately at doi:10.1594/PANGAEA.983833 .

Atmospheric methane and carbon dioxide concentrations measured during ALKOR cruise AL575 on 2022-07-12

Atmospheric carbon dioxide (CO2) and methane (CH4) concentrations were monitored during AL575 cruise on 2022-07-12 using a cavity ring down spectrometer (Picarro G2301-f CRDS) and GEOMARs 'Atmospheric Intake System' (AIS). The Picarro/AIS system was installed in the wet laboratory (starboard, main deck) of RV ALKOR and was connected by an aluminium tube to an air inlet nozzle placed at the bow of RV ALKOR. The air was pumped via the AIS intake tube with a flow rate of 2.67 litre per minute to the Picarro analyser. The atmospheric CH4, CO2, and water vapour concentrations were determined in real time at 2-3 Hz sampling rate. A time offset of 87 seconds between the air intake nozzle at the bow (6 m above sea surface) and the actual gas measurement at the Picarro was determined and the calculated flow rate considered, when correlating the gas data with navigation and weather data provided by the WERUM dship repository (https://dship.geomar.de). The weather data is published separately at doi:10.1594/PANGAEA.983833 .

Atmospheric methane and carbon dioxide concentrations measured during ALKOR cruise AL575 on 2022-07-10

Atmospheric carbon dioxide (CO2) and methane (CH4) concentrations were monitored during AL575 cruise on 2022-07-10 using a cavity ring down spectrometer (Picarro G2301-f CRDS) and GEOMARs 'Atmospheric Intake System' (AIS). The Picarro/AIS system was installed in the wet laboratory (starboard, main deck) of RV ALKOR and was connected by an aluminium tube to an air inlet nozzle placed at the bow of RV ALKOR. The air was pumped via the AIS intake tube with a flow rate of 2.67 litre per minute to the Picarro analyser. The atmospheric CH4, CO2, and water vapour concentrations were determined in real time at 2-3 Hz sampling rate. A time offset of 87 seconds between the air intake nozzle at the bow (6 m above sea surface) and the actual gas measurement at the Picarro was determined and the calculated flow rate considered, when correlating the gas data with navigation and weather data provided by the WERUM dship repository (https://dship.geomar.de). The weather data is published separately at doi:10.1594/PANGAEA.983833 .

Atmospheric methane and carbon dioxide concentrations measured during ALKOR cruise AL575 on 2022-06-29

Atmospheric carbon dioxide (CO2) and methane (CH4) concentrations were monitored during AL575 cruise on 2022-06-29 using a cavity ring down spectrometer (Picarro G2301-f CRDS) and GEOMARs 'Atmospheric Intake System' (AIS). The Picarro/AIS system was installed in the wet laboratory (starboard, main deck) of RV ALKOR and was connected by an aluminium tube to an air inlet nozzle placed at the bow of RV ALKOR. The air was pumped via the AIS intake tube with a flow rate of 2.67 litre per minute to the Picarro analyser. The atmospheric CH4, CO2, and water vapour concentrations were determined in real time at 2-3 Hz sampling rate. A time offset of 87 seconds between the air intake nozzle at the bow (6 m above sea surface) and the actual gas measurement at the Picarro was determined and the calculated flow rate considered, when correlating the gas data with navigation and weather data provided by the WERUM dship repository (https://dship.geomar.de). The weather data is published separately at doi:10.1594/PANGAEA.983833 .

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