Articles | Volume 16, issue 2
https://doi.org/10.5194/bg-16-605-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-16-605-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
01 Feb 2019
Research article |
| 01 Feb 2019
| 01 Feb 2019
High-frequency variability of CO2 in Grand Passage, Bay of Fundy, Nova Scotia
Dalhousie University, Department of Oceanography, Halifax, Nova Scotia, Canada
currently at: Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, Nova Scotia, Canada
Alex E. Hay
Dalhousie University, Department of Oceanography, Halifax, Nova Scotia, Canada
William J. Burt
Dalhousie University, Department of Oceanography, Halifax, Nova Scotia, Canada
currently at: University of British Columbia, Department of Earth, Ocean and Atmospheric Sciences, Vancouver, British Columbia, Canada
Richard A. Cheel
Dalhousie University, Department of Oceanography, Halifax, Nova Scotia, Canada
Joseph Salisbury
University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Durham, New Hampshire, USA
Helmuth Thomas
Dalhousie University, Department of Oceanography, Halifax, Nova Scotia, Canada
currently at: Helmholtz Centre Geesthacht, Institute of Coastal Research, Gessthacht,
Germany
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Feifei Liu, Ute Daewel, Jan Kossack, Kubilay Timur Demir, Helmuth Thomas, and Corinna Schrum
Biogeosciences, 22, 3699–3719, https://doi.org/10.5194/bg-22-3699-2025, https://doi.org/10.5194/bg-22-3699-2025, 2025
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Ocean alkalinity enhancement (OAE) boosts oceanic CO₂ absorption, offering a climate solution. Using a regional model, we examined OAE in the North Sea, revealing that shallow coastal areas achieve higher CO₂ uptake than offshore where alkalinity is more susceptible to deep-ocean loss. Long-term carbon storage is limited, and pH shifts vary by location. Our findings guide OAE deployment to optimize carbon removal while minimizing ecological effects, supporting global climate mitigation efforts.
Kubilay Timur Demir, Moritz Mathis, Jan Kossack, Feifei Liu, Ute Daewel, Christoph Stegert, Helmuth Thomas, and Corinna Schrum
Biogeosciences, 22, 2569–2599, https://doi.org/10.5194/bg-22-2569-2025, https://doi.org/10.5194/bg-22-2569-2025, 2025
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This study examines how variations in the ratios of carbon, nitrogen, and phosphorus in organic matter affect carbon cycling in the northwest European shelf seas. Traditional models with fixed ratios tend to underestimate biological carbon uptake. By integrating variable ratios into a regional model, we find that carbon dioxide uptake increases by 9 %–31 %. These results highlight the need to include variable ratios for accurate assessments of regional and global carbon cycles.
Claudia Elena Schmidt, Tristan Zimmermann, Katarzyna Koziorowska, Daniel Pröfrock, and Helmuth Thomas
EGUsphere, https://doi.org/10.5194/egusphere-2025-291, https://doi.org/10.5194/egusphere-2025-291, 2025
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This study explores how ocean currents, melting sea ice, and freshwater runoff alter biogeochemical cycles on the west Greenland shelf. By analyzing water samples on a high-resolution, large-scale grid, we found that these factors create distinct regional and spatial distribution patterns and significantly impact biological productivity during late summer. The study highlights the need for ongoing monitoring to understand the effects of climate change in this sensitive area.
Mona Norbisrath, Justus E. E. van Beusekom, and Helmuth Thomas
Ocean Sci., 20, 1423–1440, https://doi.org/10.5194/os-20-1423-2024, https://doi.org/10.5194/os-20-1423-2024, 2024
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We present an observational study investigating total alkalinity (TA) in the Dutch Wadden Sea. Discrete water samples were used to identify the TA spatial distribution patterns and locate and shed light on TA sources. By observing a tidal cycle, the sediments and pore water exchange were identified as local TA sources. We assumed metabolically driven CaCO3 dissolution as the TA source in the upper, oxic sediments and anaerobic metabolic processes as TA sources in the deeper, anoxic ones.
Julia Meyer, Yoana G. Voynova, Bryce Van Dam, Lara Luitjens, Dagmar Daehne, and Helmuth Thomas
EGUsphere, https://doi.org/10.5194/egusphere-2024-3048, https://doi.org/10.5194/egusphere-2024-3048, 2024
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The study highlights the inter-seasonal variability of the carbonate dynamics of the East Frisian Wadden Sea, the world's largest intertidal area. During spring, increased biological activity leads to lower CO2 and nitrate levels, while total alkalinity (TA) rises slightly. In summer, TA increases, enhancing the ocean's ability to absorb CO2. Our research emphasizes the vital role of these intertidal regions in regulating carbon, contributing to a better understanding of carbon storage.
Sacchidanandan Viruthasalam Pillai, M. Angelica Peña, Brandon J. McNabb, William J. Burt, and Philippe D. Tortell
EGUsphere, https://doi.org/10.5194/egusphere-2023-2851, https://doi.org/10.5194/egusphere-2023-2851, 2023
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We investigated how hyperspectral optical data collected in the North Pacific can be used to determine the phytoplankton community composition. We used the optically derived infomation of the phytoplankton community to examine the phytoplankton sizes, oceanographic controls and links to other biogeochemical variables. This work was motivated by the upcoming launch of the PACE satellite by NASA and the increased availability of hyperspectral optical measurements in oceanographic studies.
Mona Norbisrath, Andreas Neumann, Kirstin Dähnke, Tina Sanders, Andreas Schöl, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 20, 4307–4321, https://doi.org/10.5194/bg-20-4307-2023, https://doi.org/10.5194/bg-20-4307-2023, 2023
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Total alkalinity (TA) is the oceanic capacity to store CO2. Estuaries can be a TA source. Anaerobic metabolic pathways like denitrification (reduction of NO3− to N2) generate TA and are a major nitrogen (N) sink. Another important N sink is anammox that transforms NH4+ with NO2− into N2 without TA generation. By combining TA and N2 production, we identified a TA source, denitrification, occurring in the water column and suggest anammox as the dominant N2 producer in the bottom layer of the Ems.
Nele Lehmann, Hugues Lantuit, Michael Ernst Böttcher, Jens Hartmann, Antje Eulenburg, and Helmuth Thomas
Biogeosciences, 20, 3459–3479, https://doi.org/10.5194/bg-20-3459-2023, https://doi.org/10.5194/bg-20-3459-2023, 2023
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Riverine alkalinity in the silicate-dominated headwater catchment at subarctic Iskorasfjellet, northern Norway, was almost entirely derived from weathering of minor carbonate occurrences in the riparian zone. The uphill catchment appeared limited by insufficient contact time of weathering agents and weatherable material. Further, alkalinity increased with decreasing permafrost extent. Thus, with climate change, alkalinity generation is expected to increase in this permafrost-degrading landscape.
Mona Norbisrath, Johannes Pätsch, Kirstin Dähnke, Tina Sanders, Gesa Schulz, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 19, 5151–5165, https://doi.org/10.5194/bg-19-5151-2022, https://doi.org/10.5194/bg-19-5151-2022, 2022
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Total alkalinity (TA) regulates the oceanic storage capacity of atmospheric CO2. TA is also metabolically generated in estuaries and influences coastal carbon storage through its inflows. We used water samples and identified the Hamburg port area as the one with highest TA generation. Of the overall riverine TA load, 14 % is generated within the estuary. Using a biogeochemical model, we estimated potential effects on the coastal carbon storage under possible anthropogenic and climate changes.
Bryce Van Dam, Nele Lehmann, Mary A. Zeller, Andreas Neumann, Daniel Pröfrock, Marko Lipka, Helmuth Thomas, and Michael Ernst Böttcher
Biogeosciences, 19, 3775–3789, https://doi.org/10.5194/bg-19-3775-2022, https://doi.org/10.5194/bg-19-3775-2022, 2022
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We quantified sediment–water exchange at shallow sites in the North and Baltic seas. We found that porewater irrigation rates in the former were approximately twice as high as previously estimated, likely driven by relatively high bioirrigative activity. In contrast, we found small net fluxes of alkalinity, ranging from −35 µmol m−2 h−1 (uptake) to 53 µmol m−2 h−1 (release). We attribute this to low net denitrification, carbonate mineral (re-)precipitation, and sulfide (re-)oxidation.
Krysten Rutherford, Katja Fennel, Dariia Atamanchuk, Douglas Wallace, and Helmuth Thomas
Biogeosciences, 18, 6271–6286, https://doi.org/10.5194/bg-18-6271-2021, https://doi.org/10.5194/bg-18-6271-2021, 2021
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Using a regional model of the northwestern North Atlantic shelves in combination with a surface water time series and repeat transect observations, we investigate surface CO2 variability on the Scotian Shelf. The study highlights a strong seasonal cycle in shelf-wide pCO2 and spatial variability throughout the summer months driven by physical events. The simulated net flux of CO2 on the Scotian Shelf is out of the ocean, deviating from the global air–sea CO2 flux trend in continental shelves.
Chantal Mears, Helmuth Thomas, Paul B. Henderson, Matthew A. Charette, Hugh MacIntyre, Frank Dehairs, Christophe Monnin, and Alfonso Mucci
Biogeosciences, 17, 4937–4959, https://doi.org/10.5194/bg-17-4937-2020, https://doi.org/10.5194/bg-17-4937-2020, 2020
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Major research initiatives have been undertaken within the Arctic Ocean, highlighting this area's global importance and vulnerability to climate change. In 2015, the international GEOTRACES program addressed this importance by devoting intense research activities to the Arctic Ocean. Among various tracers, we used radium and carbonate system data to elucidate the functioning and vulnerability of the hydrographic regime of the Canadian Arctic Archipelago, bridging the Pacific and Atlantic oceans.
Fabian Schwichtenberg, Johannes Pätsch, Michael Ernst Böttcher, Helmuth Thomas, Vera Winde, and Kay-Christian Emeis
Biogeosciences, 17, 4223–4245, https://doi.org/10.5194/bg-17-4223-2020, https://doi.org/10.5194/bg-17-4223-2020, 2020
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Ocean acidification has a range of potentially harmful consequences for marine organisms. It is related to total alkalinity (TA) mainly produced in oxygen-poor situations like sediments in tidal flats. TA reduces the sensitivity of a water body to acidification. The decomposition of organic material and subsequent TA release in the tidal areas of the North Sea (Wadden Sea) is responsible for reduced acidification in the southern North Sea. This is shown with the results of an ecosystem model.
Alexis Beaupré-Laperrière, Alfonso Mucci, and Helmuth Thomas
Biogeosciences, 17, 3923–3942, https://doi.org/10.5194/bg-17-3923-2020, https://doi.org/10.5194/bg-17-3923-2020, 2020
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Ocean acidification is the process by which the oceans are changing due to carbon dioxide emissions from human activities. Studying this process in the Arctic Ocean is essential as this ocean and its ecosystems are more vulnerable to the effects of acidification. Water chemistry measurements made in recent years show that waters in and around the Canadian Arctic Archipelago are considerably affected by this process and show dynamic conditions that might have an impact on local marine organisms.
Sarah Z. Rosengard, Robert W. Izett, William J. Burt, Nina Schuback, and Philippe D. Tortell
Biogeosciences, 17, 3277–3298, https://doi.org/10.5194/bg-17-3277-2020, https://doi.org/10.5194/bg-17-3277-2020, 2020
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Net community production sets the maximum quantity of phytoplankton carbon available for the marine food web and longer-term storage in the deep ocean. We compared two approaches to estimate this critical variable from autonomous measurements of mixed-layer dissolved oxygen and particulate organic carbon, observing a significant discrepancy between estimates in an upwelling zone near the Oregon coast. We use this discrepancy to assess the fate of organic carbon produced in the mixed layer.
Louise Delaigue, Helmuth Thomas, and Alfonso Mucci
Biogeosciences, 17, 547–566, https://doi.org/10.5194/bg-17-547-2020, https://doi.org/10.5194/bg-17-547-2020, 2020
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This paper reports on the first compilation and analysis of the surface water pCO2 distribution in the Saguenay Fjord, the southernmost subarctic fjord in the Northern Hemisphere, and thus fills a significant knowledge gap in current regional estimates of estuarine CO2 emissions.
Jonathan Lemay, Helmuth Thomas, Susanne E. Craig, William J. Burt, Katja Fennel, and Blair J. W. Greenan
Biogeosciences, 15, 2111–2123, https://doi.org/10.5194/bg-15-2111-2018, https://doi.org/10.5194/bg-15-2111-2018, 2018
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We report a detailed mechanistic investigation of the impact of Hurricane Arthur on the CO2 cycling on the Scotian Shelf. We can show that in contrast to common thinking, the deepening of the surface during the summer months can lead to increased CO2 uptake as carbon-poor waters from subsurface water are brought up to the surface. Only during prolonged storm events is the deepening of the mixed layer strong enough to bring the (expected) carbon-rich water to the surface.
Jacoba Mol, Helmuth Thomas, Paul G. Myers, Xianmin Hu, and Alfonso Mucci
Biogeosciences, 15, 1011–1027, https://doi.org/10.5194/bg-15-1011-2018, https://doi.org/10.5194/bg-15-1011-2018, 2018
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In the fall of 2014, the upwelling of water from the deep Canada Basin brought water onto the shallower Mackenzie Shelf in the Beaufort Sea. This increased the concentration of CO2 in water on the shelf, which alters pH and changes the transfer of CO2 between the ocean and atmosphere. These findings were a combined result of water sampling for CO2 parameters and the use of a computer model that simulates water movement in the ocean.
Rachel Hussherr, Maurice Levasseur, Martine Lizotte, Jean-Éric Tremblay, Jacoba Mol, Helmuth Thomas, Michel Gosselin, Michel Starr, Lisa A. Miller, Tereza Jarniková, Nina Schuback, and Alfonso Mucci
Biogeosciences, 14, 2407–2427, https://doi.org/10.5194/bg-14-2407-2017, https://doi.org/10.5194/bg-14-2407-2017, 2017
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This study assesses the impact of ocean acidification on phytoplankton and its synthesis of the climate-active gas dimethyl sulfide (DMS), as well as its modulation, by two contrasting light regimes in the Arctic. The light regimes tested had no significant impact on either the phytoplankton or DMS concentration, whereas both variables decreased linearly with the decrease in pH. Thus, a rapid decrease in surface water pH could alter the algal biomass and inhibit DMS production in the Arctic.
William J. Burt, Helmuth Thomas, Lisa A. Miller, Mats A. Granskog, Tim N. Papakyriakou, and Leah Pengelly
Biogeosciences, 13, 4659–4671, https://doi.org/10.5194/bg-13-4659-2016, https://doi.org/10.5194/bg-13-4659-2016, 2016
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This study assesses the state of the carbon cycle in Hudson Bay, an ecologically important region of the Canadian Arctic. Results show that river input, sea-ice melt, biological activity, and general circulation patterns all have significant, and regionally dependent, impacts on the carbon cycle. The study also highlights the importance of detailed sampling procedures in highly stratified waters, and reveals that the deep Hudson Bay is primarily filled with waters of Pacific origin.
Fabian Große, Naomi Greenwood, Markus Kreus, Hermann-Josef Lenhart, Detlev Machoczek, Johannes Pätsch, Lesley Salt, and Helmuth Thomas
Biogeosciences, 13, 2511–2535, https://doi.org/10.5194/bg-13-2511-2016, https://doi.org/10.5194/bg-13-2511-2016, 2016
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We used the ECOHAM5 model to provide a consistent picture of the physical and biological drivers of oxygen deficiency in the North Sea. Regions susceptible to oxygen deficiency are characterised by low tidal mixing and moderate water depth (~ 40 m). Variations in upper layer productivity drive the year-to-year variability of bottom oxygen conditions. The model-based analysis reveals that benthic and pelagic remineralisation account for 90 % of bottom oxygen consumption observed at North Dogger.
N. Jiao, C. Robinson, F. Azam, H. Thomas, F. Baltar, H. Dang, N. J. Hardman-Mountford, M. Johnson, D. L. Kirchman, B. P. Koch, L. Legendre, C. Li, J. Liu, T. Luo, Y.-W. Luo, A. Mitra, A. Romanou, K. Tang, X. Wang, C. Zhang, and R. Zhang
Biogeosciences, 11, 5285–5306, https://doi.org/10.5194/bg-11-5285-2014, https://doi.org/10.5194/bg-11-5285-2014, 2014
N. Stark, A. E. Hay, R. Cheel, and C. B. Lake
Earth Surf. Dynam., 2, 469–480, https://doi.org/10.5194/esurf-2-469-2014, https://doi.org/10.5194/esurf-2-469-2014, 2014
A. E. Hay, L. Zedel, and N. Stark
Earth Surf. Dynam., 2, 443–453, https://doi.org/10.5194/esurf-2-443-2014, https://doi.org/10.5194/esurf-2-443-2014, 2014
S. E. Craig, H. Thomas, C. T. Jones, W. K. W. Li, B. J. W. Greenan, E. H. Shadwick, and W. J. Burt
Biogeosciences Discuss., https://doi.org/10.5194/bgd-10-11255-2013, https://doi.org/10.5194/bgd-10-11255-2013, 2013
Revised manuscript not accepted
W. J. Burt, H. Thomas, K. Fennel, and E. Horne
Biogeosciences, 10, 53–66, https://doi.org/10.5194/bg-10-53-2013, https://doi.org/10.5194/bg-10-53-2013, 2013
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Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022
Depositional controls and budget of organic carbon burial in fine-grained sediments of the North Sea – the Helgoland Mud Area as a natural laboratory
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Ocean alkalinity enhancement (OAE) does not cause cellular stress in a phytoplankton community of the subtropical Atlantic Ocean
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Biogeosciences, 22, 3375–3396, https://doi.org/10.5194/bg-22-3375-2025, https://doi.org/10.5194/bg-22-3375-2025, 2025
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Biogeosciences, 22, 3329–3356, https://doi.org/10.5194/bg-22-3329-2025, https://doi.org/10.5194/bg-22-3329-2025, 2025
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Darren J. Pilcher, Jessica N. Cross, Natalie Monacci, Linquan Mu, Kelly A. Kearney, Albert J. Hermann, and Wei Cheng
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The Bering Sea shelf is a highly productive marine ecosystem that is vulnerable to ocean acidification. We use a computational model to simulate the carbon cycle and acidification rates from 1970–2022. The results suggest that bottom water acidification rates are more than twice as great as surface rates. Bottom waters are also naturally more acidic. Thus these waters will pass key thresholds known to negatively impact marine organisms, such as red king crab, much sooner than surface waters.
Daniel Müller, Bo Liu, Walter Geibert, Moritz Holtappels, Lasse Sander, Elda Miramontes, Heidi Taubner, Susann Henkel, Kai-Uwe Hinrichs, Denise Bethke, Ingrid Dohrmann, and Sabine Kasten
Biogeosciences, 22, 2541–2567, https://doi.org/10.5194/bg-22-2541-2025, https://doi.org/10.5194/bg-22-2541-2025, 2025
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Coastal and shelf sediments are the most important sinks for organic carbon (OC) on Earth. We produced a new high-resolution sediment and porewater data set from the Helgoland Mud Area (HMA), North Sea, to determine which depositional factors control the preservation of OC. The burial efficiency is highest in an area of high sedimentation and terrigenous OC. The HMA covers 0.09 % of the North Sea but accounts for 0.76 % of its OC accumulation, highlighting the importance of the depocentre.
Menghong Dong, Xinyu Guo, Takuya Matsuura, Taichi Tebakari, and Jing Zhang
Biogeosciences, 22, 2383–2402, https://doi.org/10.5194/bg-22-2383-2025, https://doi.org/10.5194/bg-22-2383-2025, 2025
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M. Celeste López-Abbate, John E. Garzón-Cardona, Ricardo Silva, Juan-Carlos Molinero, Laura A. Ruiz-Etcheverry, Ana M. Martínez, Azul S. Gilabert, and Rubén J. Lara
Biogeosciences, 22, 2309–2325, https://doi.org/10.5194/bg-22-2309-2025, https://doi.org/10.5194/bg-22-2309-2025, 2025
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This study explores how microbial dynamics influence the dissolved organic matter (DOM) pool in the Patagonian Shelf. Despite high phytoplankton biomass, selective grazing on fast-growing bacteria led to DOM accumulation, likely due to reduced DOM-consuming bacteria and added egestion compounds. Experiments showed that bacteria not only acted as a carbon sink through mineralization but also transferred assimilated carbon dioxide (CO2) to higher trophic levels.
Librada Ramírez, Leonardo J. Pozzo-Pirotta, Aja Trebec, Víctor Manzanares-Vázquez, José L. Díez, Javier Arístegui, Ulf Riebesell, Stephen D. Archer, and María Segovia
Biogeosciences, 22, 1865–1886, https://doi.org/10.5194/bg-22-1865-2025, https://doi.org/10.5194/bg-22-1865-2025, 2025
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We studied the potential effects of increasing ocean alkalinity on a natural plankton community in subtropical waters of the Atlantic near Gran Canaria, Spain. Alkalinity is the capacity of water to resist acidification, and plankton are usually microscopic plants (phytoplankton) and animals (zooplankton), often less than 2.5 cm in length. This study suggests that increasing ocean alkalinity did not have a significant negative impact on the plankton community studied.
Leissing Frederick, Mauricio A. Urbina, and Ruben Escribano
Biogeosciences, 22, 1839–1852, https://doi.org/10.5194/bg-22-1839-2025, https://doi.org/10.5194/bg-22-1839-2025, 2025
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Evidence shows that due to global warming, zooplankton inhabiting the coastal upwelling zone are exposed to increasing hypoxia affecting their physiology, metabolism, and population dynamics. The adaptive responses of zooplankton to cope with mild/severe hypoxia may depend on trade-offs with other metabolic/energy demands, implying less energy for growth, feeding, and reproduction, with ecological consequences for the zooplankton population and the marine food web.
Riss M. Kell, Adam V. Subhas, Nicole L. Schanke, Lauren E. Lees, Rebecca J. Chmiel, Deepa Rao, Margaret M. Brisbin, Dawn M. Moran, Matthew R. McIlvin, Francesco Bolinesi, Olga Mangoni, Raffaella Casotti, Cecilia Balestra, Tristan Horner, Robert B. Dunbar, Andrew E. Allen, Giacomo R. DiTullio, and Mak A. Saito
EGUsphere, https://doi.org/10.1101/2023.11.05.565706, https://doi.org/10.1101/2023.11.05.565706, 2025
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Photosynthetic productivity is strongly influenced by water column nutrient availability. Despite the importance of zinc, definitive evidence for oceanic zinc limitation of photosynthesis has been scarce. We applied multiple biogeochemical measurements to a field site in Terra Nova Bay, Antarctica, to demonstrate that the phytoplankton community was experiencing zinc limitation. This field evidence paves the way for future experimental studies to consider Zn as a limiting oceanic micronutrient.
Sören Iwe, Oliver Schmale, and Bernd Schneider
Biogeosciences, 22, 1767–1779, https://doi.org/10.5194/bg-22-1767-2025, https://doi.org/10.5194/bg-22-1767-2025, 2025
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We present a novel method for quantifying N2 fixation by cyanobacteria, which is crucial in Baltic Sea eutrophication. Our Gas Equilibrium – Membrane-Inlet Mass Spectrometer (GE-MIMS), designed for operation on voluntary observing ships (VOSs), enables large-scale monitoring of surface water N2 depletion caused by N2 fixation. Laboratory tests confirm the device’s accuracy and precision, ensuring that it can complement current methods and contribute valuable data for better understanding N2 fixation in the Baltic Sea.
Caroline P. Slomp, Martijn Hermans, Niels A. G. M. van Helmond, Silke Severmann, James McManus, Marit R. van Erk, and Sairah Malkin
EGUsphere, https://doi.org/10.5194/egusphere-2025-817, https://doi.org/10.5194/egusphere-2025-817, 2025
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Cable bacteria couple oxidation of sulfide at depth in sediments with reduction of oxygen, nitrate or nitrite near the sediment surface, thereby preventing release of toxic hydrogen sulfide to the overlying water. We show evidence for a diversity of cable bacteria in sediments from hypoxic and anoxic basins along the continental margin of California and Mexico. Cable bacteria activity in this setting is likely periodic and dependent on the supply of organic matter and/or oxygen.
Jenna Alyson Lee, Joseph H. Vineis, Mathieu A. Poupon, Laure Resplandy, and Bess B. Ward
EGUsphere, https://doi.org/10.5194/egusphere-2025-871, https://doi.org/10.5194/egusphere-2025-871, 2025
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Concurrent sampling of environmental parameters, productivity rates, photopigments, and DNA were used to analyze a 24–L estuarine diatom bloom microcosm. Biogeochemical data and an ecological model indicated that the bloom was terminated by grazing. Comparisons to previous studies revealed (1) additional community and diversity complexity using 18S amplicon vs. traditional pigment–based analyses, and (2) a potential global productivity–diversity relationship using 18S and carbon transport rates.
Yong-Woo Lee, Mi-Ok Park, Seong-Gil Kim, Tae-Hoon Kim, Yong Hwa Oh, Sang Heon Lee, and DongJoo Joung
Biogeosciences, 22, 675–690, https://doi.org/10.5194/bg-22-675-2025, https://doi.org/10.5194/bg-22-675-2025, 2025
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Long-term pH variation in coastal waters along the Korean Peninsula was assessed for the first time, and it exhibited no significant pH change over an 11-year period. This contrasts with the ongoing pH decline in open oceans and other coastal areas. Analysis of environmental data showed that pH is mainly controlled by dissolved oxygen in bottom waters. This suggests that ocean warming could cause a pH decline in Korean coastal waters, affecting many fish and seaweed aquaculture operations.
Kadir Biçe, Tristen Myers Stewart, George G. Waldbusser, and Christof Meile
Biogeosciences, 22, 641–657, https://doi.org/10.5194/bg-22-641-2025, https://doi.org/10.5194/bg-22-641-2025, 2025
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We studied the effect of addition of carbonate minerals on coastal sediments. We carried out laboratory experiments to quantify the dissolution kinetics and integrated these observations into a numerical model that describes biogeochemical cycling in surficial sediments. Using the model, we demonstrate the buffering effect of the mineral additions and their duration. We quantify the effect under different environmental conditions and assess the potential for increased atmospheric CO2 uptake.
Mariche Bandibas Natividad, Jian-Jhih Chen, Hsin-Yu Chou, Lan-Feng Fan, Yi-Le Shen, and Wen-Chen Chou
EGUsphere, https://doi.org/10.5194/egusphere-2024-4000, https://doi.org/10.5194/egusphere-2024-4000, 2025
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Seagrass restoration serves as a nature-based solution for CO2 removal. We examined the organic carbon and carbonate dynamics of restored seagrasses (SG) and bare sediments (BS) using ex situ core incubations. SG exhibited higher net ecosystem metabolism compared to BS, while no significant difference was observed in net ecosystem calcification. Consequently, SG demonstrated a significantly enhanced overall capacity for carbon uptake.
Jessica L. Oberlander, Mackenzie E. Burke, Cat A. London, and Hugh L. MacIntyre
Biogeosciences, 22, 499–512, https://doi.org/10.5194/bg-22-499-2025, https://doi.org/10.5194/bg-22-499-2025, 2025
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Ocean alkalinity enhancement (OAE) is a promising negative emission technology that results in the net sequestration of atmospheric carbon. In this paper, we assess the potential impact of OAE on phytoplankton through an analysis of prior studies and the effects of simulated OAE on photosynthetic competence. Our findings suggest that there may be little if any significant impact on most phytoplankton studied to date if OAE is conducted in well-flushed, nearshore environments.
Yue Nan, Zheng Chen, Bin Wang, Bo Liang, and Jiatang Hu
EGUsphere, https://doi.org/10.5194/egusphere-2024-4013, https://doi.org/10.5194/egusphere-2024-4013, 2025
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Human activities are changing the coastal water environment, but the role of suspended sediments in oxygen loss is not well understood. We used a model to compare dissolved oxygen levels and related factors in the 1990s and 2010s in the Pearl River Estuary. Reduced suspended sediments and increased pollution have expanded low-oxygen areas by 1.5 times. It highlights that declining suspended sediments increase hypoxia in estuaries, especially with rising nutrients, which need urgent attention.
Yayla Sezginer, Kate Schuler, Emily Speciale, Adrian Marchetti, Claire Till, Ralph Till, and Philippe Tortell
EGUsphere, https://doi.org/10.5194/egusphere-2024-3812, https://doi.org/10.5194/egusphere-2024-3812, 2025
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We recorded three metrics of photosynthesis in the California Current. Real-time observations of microalgae physiology and productivity revealed signs of iron limitation where the continental shelf rapidly dropped off. Iron limitation influenced how efficiently light was absorbed and used for carbon fixation but did not appear to affect net photosynthetic oxygen production. Our results offer useful insights towards efforts to model carbon fixation rates from microalgae optical properties.
Laura Marín-Samper, Javier Arístegui, Nauzet Hernández-Hernández, and Ulf Riebesell
Biogeosciences, 21, 5707–5724, https://doi.org/10.5194/bg-21-5707-2024, https://doi.org/10.5194/bg-21-5707-2024, 2024
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This study exposed a natural community to two non-CO2-equilibrated ocean alkalinity enhancement (OAE) deployments using different minerals. Adding alkalinity in this manner decreases dissolved CO2, essential for photosynthesis. While photosynthesis was not suppressed, bloom formation was mildly delayed, potentially impacting marine food webs. The study emphasizes the need for further research on OAE without prior equilibration and on its ecological implications.
Riss M. Kell, Rebecca J. Chmiel, Deepa Rao, Dawn M. Moran, Matthew R. McIlvin, Tristan J. Horner, Nicole L. Schanke, Ichiko Sugiyama, Robert B. Dunbar, Giacomo R. DiTullio, and Mak A. Saito
Biogeosciences, 21, 5685–5706, https://doi.org/10.5194/bg-21-5685-2024, https://doi.org/10.5194/bg-21-5685-2024, 2024
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Despite interest in modeling the biogeochemical uptake and cycling of the trace metal zinc (Zn), measurements of Zn uptake in natural marine phytoplankton communities have not been conducted previously. To fill this gap, we employed a stable isotope uptake rate measurement method to quantify Zn uptake into natural phytoplankton assemblages within the Southern Ocean. Zn demand was high and rapid enough to depress the inventory of Zn available to phytoplankton on seasonal timescales.
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
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Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Michael R. Roman, Andrew H. Altieri, Denise Breitburg, Erica M. Ferrer, Natalya D. Gallo, Shin-ichi Ito, Karin Limburg, Kenneth Rose, Moriaki Yasuhara, and Lisa A. Levin
Biogeosciences, 21, 4975–5004, https://doi.org/10.5194/bg-21-4975-2024, https://doi.org/10.5194/bg-21-4975-2024, 2024
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Oxygen-depleted ocean waters have increased worldwide. In order to improve our understanding of the impacts of this oxygen loss on marine life it is essential that we develop reliable indicators that track the negative impacts of low oxygen. We review various indicators of low-oxygen stress for marine animals including their use, research needs, and application to confront the challenges of ocean oxygen loss.
Charlotte Eich, Mathijs van Manen, J. Scott P. McCain, Loay J. Jabre, Willem H. van de Poll, Jinyoung Jung, Sven B. E. H. Pont, Hung-An Tian, Indah Ardiningsih, Gert-Jan Reichart, Erin M. Bertrand, Corina P. D. Brussaard, and Rob Middag
Biogeosciences, 21, 4637–4663, https://doi.org/10.5194/bg-21-4637-2024, https://doi.org/10.5194/bg-21-4637-2024, 2024
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Phytoplankton growth in the Southern Ocean (SO) is often limited by low iron (Fe) concentrations. Sea surface warming impacts Fe availability and can affect phytoplankton growth. We used shipboard Fe clean incubations to test how changes in Fe and temperature affect SO phytoplankton. Their abundances usually increased with Fe addition and temperature increase, with Fe being the major factor. These findings imply potential shifts in ecosystem structure, impacting food webs and elemental cycling.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 21, 4469–4493, https://doi.org/10.5194/bg-21-4469-2024, https://doi.org/10.5194/bg-21-4469-2024, 2024
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Marine biological production is highly dependent on the availability of nitrogen and phosphorus. Rivers are the main source of phosphorus to the oceans but poorly represented in global model oceans. We include dissolved nitrogen and phosphorus from river export in a global model ocean and find that the addition of riverine phosphorus affects marine biology on millennial timescales more than riverine nitrogen alone. Globally, riverine phosphorus input increases primary production rates.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Marchiano Holding, and Søren Rysgaard
Biogeosciences, 21, 4037–4050, https://doi.org/10.5194/bg-21-4037-2024, https://doi.org/10.5194/bg-21-4037-2024, 2024
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In this work, we measured the chemistry of seawater from samples obtained from different depths and locations off the east coast of the Northeast Greenland National Park to determine what is influencing concentrations of dissolved CO2. Historically, the region has always been thought to take up CO2 from the atmosphere, but we show that it is possible for the region to become a source in late summer. We discuss the variables that may be related to such changes.
Lennart Thomas Bach, Aaron James Ferderer, Julie LaRoche, and Kai Georg Schulz
Biogeosciences, 21, 3665–3676, https://doi.org/10.5194/bg-21-3665-2024, https://doi.org/10.5194/bg-21-3665-2024, 2024
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Ocean alkalinity enhancement (OAE) is an emerging marine CO2 removal method, but its environmental effects are insufficiently understood. The OAE Pelagic Impact Intercomparison Project (OAEPIIP) provides funding for a standardized and globally replicated microcosm experiment to study the effects of OAE on plankton communities. Here, we provide a detailed manual for the OAEPIIP experiment. We expect OAEPIIP to help build scientific consensus on the effects of OAE on plankton.
Marlena Szeligowska, Déborah Benkort, Anna Przyborska, Mateusz Moskalik, Bernabé Moreno, Emilia Trudnowska, and Katarzyna Błachowiak-Samołyk
Biogeosciences, 21, 3617–3639, https://doi.org/10.5194/bg-21-3617-2024, https://doi.org/10.5194/bg-21-3617-2024, 2024
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The European Arctic is experiencing rapid regional warming, causing glaciers that terminate in the sea to retreat onto land. Due to this process, the area of a well-studied fjord, Hornsund, has increased by around 100 km2 (40%) since 1976. Combining satellite and in situ data with a mathematical model, we estimated that, despite some negative consequences of glacial meltwater release, such emerging coastal waters could mitigate climate change by increasing carbon uptake and storage by sediments.
Mallory C. Ringham, Nathan Hirtle, Cody Shaw, Xi Lu, Julian Herndon, Brendan R. Carter, and Matthew D. Eisaman
Biogeosciences, 21, 3551–3570, https://doi.org/10.5194/bg-21-3551-2024, https://doi.org/10.5194/bg-21-3551-2024, 2024
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Ocean alkalinity enhancement leverages the large surface area and carbon storage capacity of the oceans to store atmospheric CO2 as dissolved bicarbonate. We monitored CO2 uptake in seawater treated with NaOH to establish operational boundaries for carbon removal experiments. Results show that CO2 equilibration occurred on the order of weeks to months, was consistent with values expected from equilibration calculations, and was limited by mineral precipitation at high pH and CaCO3 saturation.
Riel Carlo O. Ingeniero, Gesa Schulz, and Hermann W. Bange
Biogeosciences, 21, 3425–3440, https://doi.org/10.5194/bg-21-3425-2024, https://doi.org/10.5194/bg-21-3425-2024, 2024
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Our research is the first to measure dissolved NO concentrations in temperate estuarine waters, providing insights into its distribution under varying conditions and enhancing our understanding of its production processes. Dissolved NO was supersaturated in the Elbe Estuary, indicating that it is a source of atmospheric NO. The observed distribution of dissolved NO most likely resulted from nitrification.
Weiyi Tang, Jeff Talbott, Timothy Jones, and Bess B. Ward
Biogeosciences, 21, 3239–3250, https://doi.org/10.5194/bg-21-3239-2024, https://doi.org/10.5194/bg-21-3239-2024, 2024
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Wastewater treatment plants (WWTPs) are known to be hotspots of greenhouse gas emissions. However, the impact of WWTPs on the emission of the greenhouse gas N2O in downstream aquatic environments is less constrained. We found spatially and temporally variable but overall higher N2O concentrations and fluxes in waters downstream of WWTPs, pointing to the need for efficient N2O removal in addition to the treatment of nitrogen in WWTPs.
Amanda Y. L. Cheong, Kogila Vani Annammala, Ee Ling Yong, Yongli Zhou, Robert S. Nichols, and Patrick Martin
Biogeosciences, 21, 2955–2971, https://doi.org/10.5194/bg-21-2955-2024, https://doi.org/10.5194/bg-21-2955-2024, 2024
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We measured nutrients and dissolved organic matter for 1 year in a eutrophic tropical estuary to understand their sources and cycling. Our data show that the dissolved organic matter originates partly from land and partly from microbial processes in the water. Internal recycling is likely important for maintaining high nutrient concentrations, and we found that there is often excess nitrogen compared to silicon and phosphorus. Our data help to explain how eutrophication persists in this system.
Aaron Ferderer, Kai G. Schulz, Ulf Riebesell, Kirralee G. Baker, Zanna Chase, and Lennart T. Bach
Biogeosciences, 21, 2777–2794, https://doi.org/10.5194/bg-21-2777-2024, https://doi.org/10.5194/bg-21-2777-2024, 2024
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Ocean alkalinity enhancement (OAE) is a promising method of atmospheric carbon removal; however, its ecological impacts remain largely unknown. We assessed the effects of simulated silicate- and calcium-based mineral OAE on diatom silicification. We found that increased silicate concentrations from silicate-based OAE increased diatom silicification. In contrast, the enhancement of alkalinity had no effect on community silicification and minimal effects on the silicification of different genera.
David González-Santana, María Segovia, Melchor González-Dávila, Librada Ramírez, Aridane G. González, Leonardo J. Pozzo-Pirotta, Veronica Arnone, Victor Vázquez, Ulf Riebesell, and J. Magdalena Santana-Casiano
Biogeosciences, 21, 2705–2715, https://doi.org/10.5194/bg-21-2705-2024, https://doi.org/10.5194/bg-21-2705-2024, 2024
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In a recent experiment off the coast of Gran Canaria (Spain), scientists explored a method called ocean alkalinization enhancement (OAE), where carbonate minerals were added to seawater. This process changed the levels of certain ions in the water, affecting its pH and buffering capacity. The researchers were particularly interested in how this could impact the levels of essential trace metals in the water.
Lucas Porz, Wenyan Zhang, Nils Christiansen, Jan Kossack, Ute Daewel, and Corinna Schrum
Biogeosciences, 21, 2547–2570, https://doi.org/10.5194/bg-21-2547-2024, https://doi.org/10.5194/bg-21-2547-2024, 2024
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Seafloor sediments store a large amount of carbon, helping to naturally regulate Earth's climate. If disturbed, some sediment particles can turn into CO2, but this effect is not well understood. Using computer simulations, we found that bottom-contacting fishing gears release about 1 million tons of CO2 per year in the North Sea, one of the most heavily fished regions globally. We show how protecting certain areas could reduce these emissions while also benefitting seafloor-living animals.
Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
Biogeosciences, 21, 2335–2354, https://doi.org/10.5194/bg-21-2335-2024, https://doi.org/10.5194/bg-21-2335-2024, 2024
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Ocean alkalinity enhancement aims to increase atmospheric CO2 sequestration by adding alkaline materials to the ocean. We assessed the environmental effects of olivine and steel slag powder on coastal plankton. Overall, slag is more efficient than olivine in releasing total alkalinity and, thus, in its ability to sequester CO2. Slag also had less environmental effect on the enclosed plankton communities when considering its higher CO2 removal potential based on this 3-week experiment.
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
Biogeosciences, 21, 2143–2158, https://doi.org/10.5194/bg-21-2143-2024, https://doi.org/10.5194/bg-21-2143-2024, 2024
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This work shows that, under a high-emission scenario, oxygen concentration in deep water of parts of the North Sea and Celtic Sea can become critically low (hypoxia) towards the end of this century. The extent and frequency of hypoxia depends on the intensity of climate change projected by different climate models. This is the result of a complex combination of factors like warming, increase in stratification, changes in the currents and changes in biological processes.
Sandy E. Tenorio and Laura Farías
Biogeosciences, 21, 2029–2050, https://doi.org/10.5194/bg-21-2029-2024, https://doi.org/10.5194/bg-21-2029-2024, 2024
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Time series studies show that CH4 is highly dynamic on the coastal ocean surface and planktonic communities are linked to CH4 accumulation, as found in coastal upwelling off Chile. We have identified the crucial role of picoplankton (> 3 µm) in CH4 recycling, especially with the addition of methylated substrates (trimethylamine and methylphosphonic acid) during upwelling and non-upwelling periods. These insights improve understanding of surface ocean CH4 recycling, aiding CH4 emission estimates.
Charlotte A. J. Williams, Tom Hull, Jan Kaiser, Claire Mahaffey, Naomi Greenwood, Matthew Toberman, and Matthew R. Palmer
Biogeosciences, 21, 1961–1971, https://doi.org/10.5194/bg-21-1961-2024, https://doi.org/10.5194/bg-21-1961-2024, 2024
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Oxygen (O2) is a key indicator of ocean health. The risk of O2 loss in the productive coastal/continental slope regions is increasing. Autonomous underwater vehicles equipped with O2 optodes provide lots of data but have problems resolving strong vertical O2 changes. Here we show how to overcome this and calculate how much O2 is supplied to the low-O2 bottom waters via mixing. Bursts in mixing supply nearly all of the O2 to bottom waters in autumn, stopping them reaching ecologically low levels.
Sabine Schmidt and Ibrahima Iris Diallo
Biogeosciences, 21, 1785–1800, https://doi.org/10.5194/bg-21-1785-2024, https://doi.org/10.5194/bg-21-1785-2024, 2024
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Along the French coast facing the Bay of Biscay, the large Gironde and Loire estuaries suffer from hypoxia. This prompted a study of the small Charente estuary located between them. This work reveals a minimum oxygen zone in the Charente estuary, which extends for about 25 km. Temperature is the main factor controlling the hypoxia. This calls for the monitoring of small turbid macrotidal estuaries that are vulnerable to hypoxia, a risk expected to increase with global warming.
Simone R. Alin, Jan A. Newton, Richard A. Feely, Samantha Siedlecki, and Dana Greeley
Biogeosciences, 21, 1639–1673, https://doi.org/10.5194/bg-21-1639-2024, https://doi.org/10.5194/bg-21-1639-2024, 2024
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We provide a new multi-stressor data product that allows us to characterize the seasonality of temperature, O2, and CO2 in the southern Salish Sea and delivers insights into the impacts of major marine heatwave and precipitation anomalies on regional ocean acidification and hypoxia. We also describe the present-day frequencies of temperature, O2, and ocean acidification conditions that cross thresholds of sensitive regional species that are economically or ecologically important.
Pamela Linford, Iván Pérez-Santos, Paulina Montero, Patricio A. Díaz, Claudia Aracena, Elías Pinilla, Facundo Barrera, Manuel Castillo, Aida Alvera-Azcárate, Mónica Alvarado, Gabriel Soto, Cécile Pujol, Camila Schwerter, Sara Arenas-Uribe, Pilar Navarro, Guido Mancilla-Gutiérrez, Robinson Altamirano, Javiera San Martín, and Camila Soto-Riquelme
Biogeosciences, 21, 1433–1459, https://doi.org/10.5194/bg-21-1433-2024, https://doi.org/10.5194/bg-21-1433-2024, 2024
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The Patagonian fjords comprise a world region where low-oxygen water and hypoxia conditions are observed. An in situ dataset was used to quantify the mechanism involved in the presence of these conditions in northern Patagonian fjords. Water mass analysis confirmed the contribution of Equatorial Subsurface Water in the advection of the low-oxygen water, and hypoxic conditions occurred when the community respiration rate exceeded the gross primary production.
Ting Wang, Buyun Du, Inke Forbrich, Jun Zhou, Joshua Polen, Elsie M. Sunderland, Prentiss H. Balcom, Celia Chen, and Daniel Obrist
Biogeosciences, 21, 1461–1476, https://doi.org/10.5194/bg-21-1461-2024, https://doi.org/10.5194/bg-21-1461-2024, 2024
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The strong seasonal increases of Hg in aboveground biomass during the growing season and the lack of changes observed after senescence in this salt marsh ecosystem suggest physiologically controlled Hg uptake pathways. The Hg sources found in marsh aboveground tissues originate from a mix of sources, unlike terrestrial ecosystems, where atmospheric GEM is the main source. Belowground plant tissues mostly take up Hg from soils. Overall, the salt marsh currently serves as a small net Hg sink.
Eleanor Simpson, Debby Ianson, Karen E. Kohfeld, Ana C. Franco, Paul A. Covert, Marty Davelaar, and Yves Perreault
Biogeosciences, 21, 1323–1353, https://doi.org/10.5194/bg-21-1323-2024, https://doi.org/10.5194/bg-21-1323-2024, 2024
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Shellfish aquaculture operates in nearshore areas where data on ocean acidification parameters are limited. We show daily and seasonal variability in pH and saturation states of calcium carbonate at nearshore aquaculture sites in British Columbia, Canada, and determine the contributing drivers of this variability. We find that nearshore locations have greater variability than open waters and that the uptake of carbon by phytoplankton is the major driver of pH and saturation state variability.
S. Alejandra Castillo Cieza, Rachel H. R. Stanley, Pierre Marrec, Diana N. Fontaine, E. Taylor Crockford, Dennis J. McGillicuddy Jr., Arshia Mehta, Susanne Menden-Deuer, Emily E. Peacock, Tatiana A. Rynearson, Zoe O. Sandwith, Weifeng Zhang, and Heidi M. Sosik
Biogeosciences, 21, 1235–1257, https://doi.org/10.5194/bg-21-1235-2024, https://doi.org/10.5194/bg-21-1235-2024, 2024
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The coastal ocean in the northeastern USA provides many services, including fisheries and habitats for threatened species. In summer 2019, a bloom occurred of a large unusual phytoplankton, the diatom Hemiaulus, with nitrogen-fixing symbionts. This led to vast changes in productivity and grazing rates in the ecosystem. This work shows that the emergence of one species can have profound effects on ecosystem function. Such changes may become more prevalent as the ocean warms due to climate change.
Claudine Hauri, Brita Irving, Sam Dupont, Rémi Pagés, Donna D. W. Hauser, and Seth L. Danielson
Biogeosciences, 21, 1135–1159, https://doi.org/10.5194/bg-21-1135-2024, https://doi.org/10.5194/bg-21-1135-2024, 2024
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Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. We present pH and pCO2 time series (2016–2020) from the Chukchi Ecosystem Observatory and analyze the drivers of the current conditions to get a better understanding of how climate change and ocean acidification could affect the ecological niches of organisms.
William Hiles, Lucy C. Miller, Craig Smeaton, and William E. N. Austin
Biogeosciences, 21, 929–948, https://doi.org/10.5194/bg-21-929-2024, https://doi.org/10.5194/bg-21-929-2024, 2024
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Saltmarsh soils may help to limit the rate of climate change by storing carbon. To understand their impacts, they must be accurately mapped. We use drone data to estimate the size of three saltmarshes in NE Scotland. We find that drone imagery, combined with tidal data, can reliably inform our understanding of saltmarsh size. When compared with previous work using vegetation communities, we find that our most reliable new estimates of stored carbon are 15–20 % smaller than previously estimated.
De'Marcus Robinson, Anh L. D. Pham, David J. Yousavich, Felix Janssen, Frank Wenzhöfer, Eleanor C. Arrington, Kelsey M. Gosselin, Marco Sandoval-Belmar, Matthew Mar, David L. Valentine, Daniele Bianchi, and Tina Treude
Biogeosciences, 21, 773–788, https://doi.org/10.5194/bg-21-773-2024, https://doi.org/10.5194/bg-21-773-2024, 2024
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The present study suggests that high release of ferrous iron from the seafloor of the oxygen-deficient Santa Barabara Basin (California) supports surface primary productivity, creating positive feedback on seafloor iron release by enhancing low-oxygen conditions in the basin.
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhöfer, Felix Janssen, Na Liu, Jonathan Tarn, Franklin Kinnaman, David L. Valentine, and Tina Treude
Biogeosciences, 21, 789–809, https://doi.org/10.5194/bg-21-789-2024, https://doi.org/10.5194/bg-21-789-2024, 2024
Short summary
Short summary
Declining oxygen (O2) concentrations in coastal oceans can threaten people’s ways of life and food supplies. Here, we investigate how mats of bacteria that proliferate on the seafloor of the Santa Barbara Basin sustain and potentially worsen these O2 depletion events through their unique chemoautotrophic metabolism. Our study shows how changes in seafloor microbiology and geochemistry brought on by declining O2 concentrations can help these mats grow as well as how that growth affects the basin.
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Short summary
High-frequency CO2 measurements are used to quantify the daily and tidal cycles of dissolved carbon in the Bay of Fundy – home to the world's largest tides. The oscillating tidal flows drive a net carbon transport, and these results suggest that previously unaccounted for tidal variation could substantially modulate the coastal ocean's response to global ocean acidification. Evaluating the impact of rising atmospheric CO2 on coastal systems requires understanding this short-term variability.
High-frequency CO2 measurements are used to quantify the daily and tidal cycles of dissolved...
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