Articles | Volume 18, issue 12
https://doi.org/10.5194/bg-18-3903-2021
© Author(s) 2021. 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-18-3903-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
30 Jun 2021
Research article |
| 30 Jun 2021
| 30 Jun 2021
Permanent ectoplasmic structures in deep-sea Cibicides and Cibicidoides taxa – long-term observations at in situ pressure
Jutta E. Wollenburg
CORRESPONDING AUTHOR
Alfred-Wegener-Institut Helmholtz-Zentrum für
Polar- und Meeresforschung, Bremerhaven, 27570, Germany
Jelle Bijma
Alfred-Wegener-Institut Helmholtz-Zentrum für
Polar- und Meeresforschung, Bremerhaven, 27570, Germany
Charlotte Cremer
Alfred-Wegener-Institut Helmholtz-Zentrum für
Polar- und Meeresforschung, Bremerhaven, 27570, Germany
Ulf Bickmeyer
Alfred-Wegener-Institut Helmholtz-Zentrum für
Polar- und Meeresforschung, Bremerhaven, 27570, Germany
Zora Mila Colomba Zittier
Alfred-Wegener-Institut Helmholtz-Zentrum für
Polar- und Meeresforschung, Bremerhaven, 27570, Germany
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Tsai-Wen Lin, Tommaso Tesi, Jens Hefter, Hendrik Grotheer, Jutta Wollenburg, Florian Adolphi, Henning A. Bauch, Alessio Nogarotto, Juliane Müller, and Gesine Mollenhauer
Clim. Past, 21, 753–772, https://doi.org/10.5194/cp-21-753-2025, https://doi.org/10.5194/cp-21-753-2025, 2025
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In order to understand the mechanisms governing permafrost organic matter remobilization, we investigated organic matter composition during past intervals of rapid sea-level rise, of inland warming, and of dense sea-ice cover in the Laptev Sea. We find that sea-level rise resulted in widespread erosion and transport of permafrost materials to the ocean but that erosion is mitigated by regional dense sea-ice cover. Factors like inland warming or floods increase permafrost mobilization locally.
Arnaud Nicolas, Gesine Mollenhauer, Johannes Lachner, Konstanze Stübner, Maylin Malter, Jutta Wollenburg, Hendrik Grotheer, and Florian Adolphi
Clim. Past, 20, 2617–2628, https://doi.org/10.5194/cp-20-2617-2024, https://doi.org/10.5194/cp-20-2617-2024, 2024
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We use the authigenic 10Be/9Be record of a Laptev Sea sediment core for the period 8–14 kyr BP and synchronize it with the 10Be records from absolutely dated ice cores. We employed a likelihood function to calculate the ΔR values. A benthic ΔR value of +345±60 14C years was estimated, which corresponds to a marine reservoir age of 848±90 14C years. This new ΔR value was used to refine the age–depth model for core PS2458-4, establishing it as a potential reference chronology for the Laptev Sea.
Jutta E. Wollenburg, Morten Iversen, Christian Katlein, Thomas Krumpen, Marcel Nicolaus, Giulia Castellani, Ilka Peeken, and Hauke Flores
The Cryosphere, 14, 1795–1808, https://doi.org/10.5194/tc-14-1795-2020, https://doi.org/10.5194/tc-14-1795-2020, 2020
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Based on an observed omnipresence of gypsum crystals, we concluded that their release from melting sea ice is a general feature in the Arctic Ocean. Individual gypsum crystals sank at more than 7000 m d−1, suggesting that they are an important ballast mineral. Previous observations found gypsum inside phytoplankton aggregates at 2000 m depth, supporting gypsum as an important driver for pelagic-benthic coupling in the ice-covered Arctic Ocean.
Gabriel West, Darrell S. Kaufman, Francesco Muschitiello, Matthias Forwick, Jens Matthiessen, Jutta Wollenburg, and Matt O'Regan
Geochronology, 1, 53–67, https://doi.org/10.5194/gchron-1-53-2019, https://doi.org/10.5194/gchron-1-53-2019, 2019
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We report amino acid racemization analyses of foraminifera from well-dated sediment cores from the Yermak Plateau, Arctic Ocean. Sample ages are compared with model predictions, revealing that the rates of racemization generally conform to a global compilation of racemization rates at deep-sea sites. These results highlight the need for further studies to test and explain the origin of the purportedly high rate of racemization indicated by previous analyses of central Arctic sediments.
Jelle Bijma, Mathilde Hagens, Jens Hammes, Noah Planavsky, Philip A. E. Pogge von Strandmann, Tom Reershemius, Christopher T. Reinhard, Phil Renforth, Tim Jesper Suhrhoff, Sara Vicca, Arthur Vienne, and Dieter A. Wolf-Gladrow
EGUsphere, https://doi.org/10.5194/egusphere-2025-2740, https://doi.org/10.5194/egusphere-2025-2740, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
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Enhanced rock weathering is a nature based negative emission technology, that permanently stores CO2. It requires rock-flour to be added to arable land with the help of farmers. To be eligible for carbon credits calls for a simple but scientifically solid, so called, Monitoring, Reporting & Verification” (MRV). We demonstrate that the commonly used carbon-based accounting is ill-suited to close the balance in open systems such as arable land, and argue for cation-based accounting strategy.
Elwyn de la Vega, Markus Raitzsch, Gavin Foster, Jelle Bijma, Ulysses Silas Ninnemann, Michal Kucera, Tali Lea Babila, Jessica Crumpton Banks, Mohamed M. Ezat, and Audrey Morley
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This preprint is open for discussion and under review for Biogeosciences (BG).
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The boron isotopic composition (δ11B) of foraminifera shells is an established proxy for the reconstruction of ocean pH. Applications to the Arctic oceans are however limited as robust calibrations in these regions are lacking. Here, we present a new calibration linking δ11B measured in two high-latitude foraminifera species to seawater pH. We show that the δ11B of the species analysed is well correlated with seawater pH and that this calibration can be applied to the paleorecord.
Tsai-Wen Lin, Tommaso Tesi, Jens Hefter, Hendrik Grotheer, Jutta Wollenburg, Florian Adolphi, Henning A. Bauch, Alessio Nogarotto, Juliane Müller, and Gesine Mollenhauer
Clim. Past, 21, 753–772, https://doi.org/10.5194/cp-21-753-2025, https://doi.org/10.5194/cp-21-753-2025, 2025
Short summary
Short summary
In order to understand the mechanisms governing permafrost organic matter remobilization, we investigated organic matter composition during past intervals of rapid sea-level rise, of inland warming, and of dense sea-ice cover in the Laptev Sea. We find that sea-level rise resulted in widespread erosion and transport of permafrost materials to the ocean but that erosion is mitigated by regional dense sea-ice cover. Factors like inland warming or floods increase permafrost mobilization locally.
Arnaud Nicolas, Gesine Mollenhauer, Johannes Lachner, Konstanze Stübner, Maylin Malter, Jutta Wollenburg, Hendrik Grotheer, and Florian Adolphi
Clim. Past, 20, 2617–2628, https://doi.org/10.5194/cp-20-2617-2024, https://doi.org/10.5194/cp-20-2617-2024, 2024
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We use the authigenic 10Be/9Be record of a Laptev Sea sediment core for the period 8–14 kyr BP and synchronize it with the 10Be records from absolutely dated ice cores. We employed a likelihood function to calculate the ΔR values. A benthic ΔR value of +345±60 14C years was estimated, which corresponds to a marine reservoir age of 848±90 14C years. This new ΔR value was used to refine the age–depth model for core PS2458-4, establishing it as a potential reference chronology for the Laptev Sea.
Julie Meilland, Michael Siccha, Maike Kaffenberger, Jelle Bijma, and Michal Kucera
Biogeosciences, 18, 5789–5809, https://doi.org/10.5194/bg-18-5789-2021, https://doi.org/10.5194/bg-18-5789-2021, 2021
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Planktonic foraminifera population dynamics has long been assumed to be controlled by synchronous reproduction and ontogenetic vertical migration (OVM). Due to contradictory observations, this concept became controversial. We here test it in the Atlantic ocean for four species of foraminifera representing the main clades. Our observations support the existence of synchronised reproduction and OVM but show that more than half of the population does not follow the canonical trajectory.
Markus Raitzsch, Jelle Bijma, Torsten Bickert, Michael Schulz, Ann Holbourn, and Michal Kučera
Clim. Past, 17, 703–719, https://doi.org/10.5194/cp-17-703-2021, https://doi.org/10.5194/cp-17-703-2021, 2021
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At approximately 14 Ma, the East Antarctic Ice Sheet expanded to almost its current extent, but the role of CO2 in this major climate transition is not entirely known. We show that atmospheric CO2 might have varied on 400 kyr cycles linked to the eccentricity of the Earth’s orbit. The resulting change in weathering and ocean carbon cycle affected atmospheric CO2 in a way that CO2 rose after Antarctica glaciated, helping to stabilize the climate system on its way to the “ice-house” world.
Delphine Dissard, Gert Jan Reichart, Christophe Menkes, Morgan Mangeas, Stephan Frickenhaus, and Jelle Bijma
Biogeosciences, 18, 423–439, https://doi.org/10.5194/bg-18-423-2021, https://doi.org/10.5194/bg-18-423-2021, 2021
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Results from a data set acquired from living foraminifera T. sacculifer collected from surface waters are presented, allowing us to establish a new Mg/Ca–Sr/Ca–temperature equation improving temperature reconstructions. When combining equations, δ18Ow can be reconstructed with a precision of ± 0.5 ‰, while successive reconstructions involving Mg/Ca and δ18Oc preclude salinity reconstruction with a precision better than ± 1.69. A new direct linear fit to reconstruct salinity could be established.
Markus Raitzsch, Claire Rollion-Bard, Ingo Horn, Grit Steinhoefel, Albert Benthien, Klaus-Uwe Richter, Matthieu Buisson, Pascale Louvat, and Jelle Bijma
Biogeosciences, 17, 5365–5375, https://doi.org/10.5194/bg-17-5365-2020, https://doi.org/10.5194/bg-17-5365-2020, 2020
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The isotopic composition of boron in carbonate shells of marine unicellular organisms is a popular tool to estimate seawater pH. Usually, many shells need to be dissolved and measured for boron isotopes, but the information on their spatial distribution is lost. Here, we investigate two techniques that allow for measuring boron isotopes within single shells and show that they yield robust mean values but provide additional information on the heterogeneity within and between single shells.
Jutta E. Wollenburg, Morten Iversen, Christian Katlein, Thomas Krumpen, Marcel Nicolaus, Giulia Castellani, Ilka Peeken, and Hauke Flores
The Cryosphere, 14, 1795–1808, https://doi.org/10.5194/tc-14-1795-2020, https://doi.org/10.5194/tc-14-1795-2020, 2020
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Based on an observed omnipresence of gypsum crystals, we concluded that their release from melting sea ice is a general feature in the Arctic Ocean. Individual gypsum crystals sank at more than 7000 m d−1, suggesting that they are an important ballast mineral. Previous observations found gypsum inside phytoplankton aggregates at 2000 m depth, supporting gypsum as an important driver for pelagic-benthic coupling in the ice-covered Arctic Ocean.
Jan Goleń, Jarosław Tyszka, Ulf Bickmeyer, and Jelle Bijma
Biogeosciences, 17, 995–1011, https://doi.org/10.5194/bg-17-995-2020, https://doi.org/10.5194/bg-17-995-2020, 2020
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We studied the organisation and dynamics of actin in foraminifera. Actin is one of the key structural proteins in most lifeforms. Our investigations show that in foraminifera it forms small granules, around 1 µm in diameter, that display rapid movement. This granularity is unusual in comparison to other organisms. We suppose that these granules are most likely involved in the formation of all types of pseudopods responsible for movement, food capturing, biomineralisation, and other functions.
Gabriel West, Darrell S. Kaufman, Francesco Muschitiello, Matthias Forwick, Jens Matthiessen, Jutta Wollenburg, and Matt O'Regan
Geochronology, 1, 53–67, https://doi.org/10.5194/gchron-1-53-2019, https://doi.org/10.5194/gchron-1-53-2019, 2019
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We report amino acid racemization analyses of foraminifera from well-dated sediment cores from the Yermak Plateau, Arctic Ocean. Sample ages are compared with model predictions, revealing that the rates of racemization generally conform to a global compilation of racemization rates at deep-sea sites. These results highlight the need for further studies to test and explain the origin of the purportedly high rate of racemization indicated by previous analyses of central Arctic sediments.
Mattia Greco, Lukas Jonkers, Kerstin Kretschmer, Jelle Bijma, and Michal Kucera
Biogeosciences, 16, 3425–3437, https://doi.org/10.5194/bg-16-3425-2019, https://doi.org/10.5194/bg-16-3425-2019, 2019
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To be able to interpret the paleoecological signal contained in N. pachyderma's shells, its habitat depth must be known. Our investigation on 104 density profiles of this species from the Arctic and North Atlantic shows that specimens reside closer to the surface when sea-ice and/or surface chlorophyll concentrations are high. This is in contrast with previous investigations that pointed at the position of the deep chlorophyll maximum as the main driver of N. pachyderma vertical distribution.
Eveline M. Mezger, Lennart J. de Nooijer, Jacqueline Bertlich, Jelle Bijma, Dirk Nürnberg, and Gert-Jan Reichart
Biogeosciences, 16, 1147–1165, https://doi.org/10.5194/bg-16-1147-2019, https://doi.org/10.5194/bg-16-1147-2019, 2019
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Seawater salinity is an important factor when trying to reconstruct past ocean conditions. Foraminifera, small organisms living in the sea, produce shells that incorporate more Na at higher salinities. The accuracy of reconstructions depends on the fundamental understanding involved in the incorporation and preservation of the original Na of the shell. In this study, we unravel the Na composition of different components of the shell and describe the relative contribution of these components.
Jacqueline Bertlich, Dirk Nürnberg, Ed C. Hathorne, Lennart J. de Nooijer, Eveline M. Mezger, Markus Kienast, Steffanie Nordhausen, Gert-Jan Reichart, Joachim Schönfeld, and Jelle Bijma
Biogeosciences, 15, 5991–6018, https://doi.org/10.5194/bg-15-5991-2018, https://doi.org/10.5194/bg-15-5991-2018, 2018
Lennart J. de Nooijer, Anieke Brombacher, Antje Mewes, Gerald Langer, Gernot Nehrke, Jelle Bijma, and Gert-Jan Reichart
Biogeosciences, 14, 3387–3400, https://doi.org/10.5194/bg-14-3387-2017, https://doi.org/10.5194/bg-14-3387-2017, 2017
Ella L. Howes, Karina Kaczmarek, Markus Raitzsch, Antje Mewes, Nienke Bijma, Ingo Horn, Sambuddha Misra, Jean-Pierre Gattuso, and Jelle Bijma
Biogeosciences, 14, 415–430, https://doi.org/10.5194/bg-14-415-2017, https://doi.org/10.5194/bg-14-415-2017, 2017
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To calculate the seawater carbonate system, proxies for 2 out of 7 parameters are required. The boron isotopic composition of foraminifera shells can be used as a proxy for pH and it has been suggested that B / Ca ratios may act as a proxy for carbonate ion concentration. However, differentiating between the effects of pH and [CO32−] is problematic, as they co-vary in natural systems. To deconvolve the effects, we conducted culture experiments with the planktonic foraminifer Orbulina universa.
G. Dishon, J. Fisch, I. Horn, K. Kaczmarek, J. Bijma, D. F. Gruber, O. Nir, Y. Popovich, and D. Tchernov
Biogeosciences, 12, 5677–5687, https://doi.org/10.5194/bg-12-5677-2015, https://doi.org/10.5194/bg-12-5677-2015, 2015
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This paper offers a new methodology to study paleo-coral bleaching events using high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry. Coral bleaching records only go back several decades, but this new proxy allows the study of bleaching events that occurred tens of thousands of years ago. Unlike other methods, the high-resolution of the method can detect bleaching events that occur over very short time periods, just a few weeks.
A. Mewes, G. Langer, S. Thoms, G. Nehrke, G.-J. Reichart, L. J. de Nooijer, and J. Bijma
Biogeosciences, 12, 2153–2162, https://doi.org/10.5194/bg-12-2153-2015, https://doi.org/10.5194/bg-12-2153-2015, 2015
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A culture study with the benthic foraminifer Amphistegina lessonii was conducted at varying seawater [Ca2+] and constant [Mg2+]. Results showed optimum growth rates and test thickness at ambient seawater Mg/Ca and a calcite Mg/Ca which is controlled by the relative seawater ratio. Results support the conceptual biomineralization model by Nehrke et al. (2013); however, our refined flux-based model suggests transmembrane transport fractionation that is slightly weaker than expected.
K. Kaczmarek, G. Langer, G. Nehrke, I. Horn, S. Misra, M. Janse, and J. Bijma
Biogeosciences, 12, 1753–1763, https://doi.org/10.5194/bg-12-1753-2015, https://doi.org/10.5194/bg-12-1753-2015, 2015
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Culture experiments based on a decoupled pH and CO32- chemistry indicate that the δ11B of the test of A. lessonii is related to pH whereas the B/Ca of the foraminiferal shells show a positive correlation with B(OH)4-/HCO3-. The latter observation suggests a competition between B(OH)4- and HCO3- of the culture media for B uptake into the test.
G. Langer, G. Nehrke, C. Baggini, R. Rodolfo-Metalpa, J. M. Hall-Spencer, and J. Bijma
Biogeosciences, 11, 7363–7368, https://doi.org/10.5194/bg-11-7363-2014, https://doi.org/10.5194/bg-11-7363-2014, 2014
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Specimens of the patellogastropod limpet Patella caerulea were collected within and outside a CO2 vent site at Ischia, Italy. The distribution of different crystal structures across shell sections was analysed. Patella caerulea counteracts shell dissolution in corrosive waters by enhanced production of aragonitic parts of the shell. We conclude that it is not possible to predict the dissolution behaviour of a composite biomineral on the basis of the properties of its constituent mineral.
G. Nehrke, N. Keul, G. Langer, L. J. de Nooijer, J. Bijma, and A. Meibom
Biogeosciences, 10, 6759–6767, https://doi.org/10.5194/bg-10-6759-2013, https://doi.org/10.5194/bg-10-6759-2013, 2013
N. Keul, G. Langer, L. J. de Nooijer, and J. Bijma
Biogeosciences, 10, 6185–6198, https://doi.org/10.5194/bg-10-6185-2013, https://doi.org/10.5194/bg-10-6185-2013, 2013
D. Bögner, U. Bickmeyer, and A. Köhler
Biogeosciences Discuss., https://doi.org/10.5194/bgd-10-8027-2013, https://doi.org/10.5194/bgd-10-8027-2013, 2013
Revised manuscript not accepted
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Ewa Demianiuk, Mateusz Baca, Danijela Popović, Inès Barrenechea Angeles, Ngoc-Loi Nguyen, Jan Pawlowski, John B. Anderson, and Wojciech Majewski
Biogeosciences, 22, 2601–2620, https://doi.org/10.5194/bg-22-2601-2025, https://doi.org/10.5194/bg-22-2601-2025, 2025
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Ancient foraminiferal DNA is studied in five Antarctic cores with sediments up to 25 kyr old. We use a standard and a new, more effective marker, which may become the next standard for paleoenvironmental studies. Much less diverse foraminifera occur on slopes of submarine moraines than in open-marine settings. Soft-walled foraminifera, not found in the fossil record, are especially abundant. There is no foraminiferal DNA in tills, suggesting its destruction during glacial redeposition.
Isabell Hochfeld, Ben A. Ward, Anke Kremp, Juliane Romahn, Alexandra Schmidt, Miklós Bálint, Lutz Becks, Jérôme Kaiser, Helge W. Arz, Sarah Bolius, Laura S. Epp, Markus Pfenninger, Christopher A. Klausmeier, Elena Litchman, and Jana Hinners
Biogeosciences, 22, 2363–2380, https://doi.org/10.5194/bg-22-2363-2025, https://doi.org/10.5194/bg-22-2363-2025, 2025
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Marine ecosystem models (MEMs) are valuable for assessing the threats of global warming to biodiversity and ecosystem functioning, but their predictions vary widely. We argue that MEMs should consider evolutionary processes and undergo independent validation. Here, we present a novel framework for MEM development using validation data from sediment archives, which map long-term environmental and evolutionary change. Our approach is a crucial step towards improving the predictive power of MEMs.
Goulwen Le Guevel, Fabrice Minoletti, Carla Geisen, Gwendoline Duong, Virginia Rojas, and Michaël Hermoso
Biogeosciences, 22, 2287–2308, https://doi.org/10.5194/bg-22-2287-2025, https://doi.org/10.5194/bg-22-2287-2025, 2025
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This study explores the impact of environmental conditions on the chemistry of coccoliths, calcite minerals produced by marine algae, to better understand past climate changes. By cultivating different species of coccolithophores under various CO2 and pH levels, we have shown that the isotopic composition of certain species varies with CO2 concentration and quantified these variations.
Flor Vermassen, Clare Bird, Tirza M. Weitkamp, Kate F. Darling, Hanna Farnelid, Céline Heuzé, Allison Y. Hsiang, Salar Karam, Christian Stranne, Marcus Sundbom, and Helen K. Coxall
Biogeosciences, 22, 2261–2286, https://doi.org/10.5194/bg-22-2261-2025, https://doi.org/10.5194/bg-22-2261-2025, 2025
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We provide the first systematic survey of planktonic foraminifera in the high Arctic Ocean. Our results describe the abundance and species composition under summer sea ice. They indicate that the polar specialist N. pachyderma is the only species present, with subpolar species absent. The data set will be a valuable reference for continued monitoring of the state of planktonic foraminifera communities as they respond to the ongoing sea-ice decline and the “Atlantification” of the Arctic Ocean.
Kristin Jones, Lenaïg G. Hemery, Nicholas D. Ward, Peter J. Regier, Mallory C. Ringham, and Matthew D. Eisaman
Biogeosciences, 22, 1615–1630, https://doi.org/10.5194/bg-22-1615-2025, https://doi.org/10.5194/bg-22-1615-2025, 2025
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Ocean alkalinity enhancement is a marine carbon dioxide removal method that aims to mitigate the effects of climate change. This method causes localized increases in ocean pH, but the biological impacts of such changes are not well known. Our study investigated the response of two nearshore invertebrate species to increased pH and found the sea hare to be sensitive to pH changes, whereas the isopod was more resilient. Understanding interactions with biology is important as this field expands.
Renée P. Schoeman, Christine Erbe, and Robert D. McCauley
Biogeosciences, 22, 959–974, https://doi.org/10.5194/bg-22-959-2025, https://doi.org/10.5194/bg-22-959-2025, 2025
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Marine habitat models do not include deep chlorophyll maxima, which may support higher trophic level foraging in (meso-)oligotrophic habitats. We used ocean glider data to show that chlorophyll maxima form off Western Australia in September–April. At least 50 % were biomass maxima, likely supporting local krill growing sufficiently for whale consumption. We suggest including deep chlorophyll maxima in marine habitat models as deep depth-integrated estimates from satellite-derived surface values.
Giulia Faucher, Mathias Haunost, Allanah Joy Paul, Anne Ulrike Christiane Tietz, and Ulf Riebesell
Biogeosciences, 22, 405–415, https://doi.org/10.5194/bg-22-405-2025, https://doi.org/10.5194/bg-22-405-2025, 2025
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Ocean alkalinity enhancement (OAE) is being evaluated for its capacity to absorb atmospheric CO2 in the ocean and store it long term to mitigate climate change. As researchers plan for field tests to gain insights into OAE, sharing knowledge on its environmental impact on marine ecosystems is urgent. Our study examined NaOH-induced OAE in Emiliania huxleyi, a key coccolithophore species, and found that the added total alkalinity (ΔTA) should stay below 600 µmol kg⁻¹ to avoid negative impacts.
Isabell Hochfeld and Jana Hinners
Biogeosciences, 21, 5591–5611, https://doi.org/10.5194/bg-21-5591-2024, https://doi.org/10.5194/bg-21-5591-2024, 2024
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Ecosystem models disagree on future changes in marine ecosystem functioning. We suspect that the lack of phytoplankton adaptation represents a major uncertainty factor, given the key role that phytoplankton play in marine ecosystems. Using an evolutionary ecosystem model, we found that phytoplankton adaptation can notably change simulated ecosystem dynamics. Future models should include phytoplankton adaptation; otherwise they can systematically overestimate future ecosystem-level changes.
Evert de Froe, Igor Yashayaev, Christian Mohn, Johanne Vad, Furu Mienis, Gerard Duineveld, Ellen Kenchington, Erica Head, Steve W. Ross, Sabena Blackbird, George A. Wolff, J. Murray Roberts, Barry MacDonald, Graham Tulloch, and Dick van Oevelen
Biogeosciences, 21, 5407–5433, https://doi.org/10.5194/bg-21-5407-2024, https://doi.org/10.5194/bg-21-5407-2024, 2024
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Deep-sea sponge grounds are distributed globally and are considered hotspots of biological diversity and biogeochemical cycling. To date, little is known about the environmental constraints that control where deep-sea sponge grounds occur and what conditions favour high sponge biomass. Here, we characterize oceanographic conditions at two contrasting sponge grounds. Our results imply that sponges and associated fauna benefit from strong tidal currents and favourable regional ocean currents.
Francisco Javier Díaz-Rosas, Cristian Antonio Vargas, and Peter von Dassow
EGUsphere, https://doi.org/10.5194/egusphere-2024-3463, https://doi.org/10.5194/egusphere-2024-3463, 2024
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We studied Particulate Inorganic Carbon (PIC) and coccolithophores in low-oxygen, low-pH waters off the Southeast Pacific margin. We estimated how much PIC is produced by coccolithophores, which supports carbon transport to ocean depths. Results show coccolithophores can thrive in these zones, though their role in carbon export may lessen. This work advances understanding of coccolithophores’ role in carbon cycling as ocean acidification changes marine chemistry.
Kirsty Marie Edgar, Maria Grigoratou, Fanny Monteiro, Ruby Barrett, Rui Ying, and Daniela Schmidt
EGUsphere, https://doi.org/10.5194/egusphere-2024-3295, https://doi.org/10.5194/egusphere-2024-3295, 2024
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Planktic foraminifera are microscopic marine organisms whose calcium carbonate shells provide valuable insights into past ocean conditions. A promising means of understanding foraminiferal ecology and their environmental interactions is to constrain their key functional traits relating to feeding, symbioses, motility, calcification and reproduction. Here we review what we know of their functional traits, key gaps in our understanding and suggestions on how to fill them.
Hyunjae Chung, Jikang Park, Mijin Park, Yejin Kim, Unyoung Chun, Sukyoung Yun, Won Sang Lee, Hyun A. Choi, Ji Sung Na, Seung-Tae Yoon, and Won Young Lee
Biogeosciences, 21, 5199–5217, https://doi.org/10.5194/bg-21-5199-2024, https://doi.org/10.5194/bg-21-5199-2024, 2024
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Understanding how marine animals adapt to variations in marine environmental conditions is paramount. In this paper, we investigated the influence of changes in seawater and light conditions on the seasonal foraging behavior of Weddell seals in the Ross Sea, Antarctica. Our findings could serve as a baseline and establish a foundational understanding for future research, particularly concerning the impact of marine environmental changes on the ecosystem of the Ross Sea Marine Protected Area.
Anaïs Lebrun, Cale A. Miller, Marc Meynadier, Steeve Comeau, Pierre Urrutti, Samir Alliouane, Robert Schlegel, Jean-Pierre Gattuso, and Frédéric Gazeau
Biogeosciences, 21, 4605–4620, https://doi.org/10.5194/bg-21-4605-2024, https://doi.org/10.5194/bg-21-4605-2024, 2024
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We tested the effects of warming, low salinity, and low irradiance on Arctic kelps. We show that growth rates were similar across species and treatments. Alaria esculenta is adapted to low-light conditions. Saccharina latissima exhibited nitrogen limitation, suggesting coastal erosion and permafrost thawing could be beneficial. Laminaria digitata did not respond to the treatments. Gene expression of Hedophyllum nigripes and S. latissima indicated acclimation to the experimental treatments.
Valeria Ana Guinder, Urban Tillmann, Martin Rivarossa, Carola Ferronato, Fernando Javier Ramirez, Bernd Krock, Haifeng Gu, and Martin Saraceno
EGUsphere, https://doi.org/10.5194/egusphere-2024-3157, https://doi.org/10.5194/egusphere-2024-3157, 2024
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An unusual survey involving two vessels in the Argentine Sea over a ten-day period enabled synoptic observations of a significant bloom of toxic phytoplankton. Simultaneous species characterization of the bloom, along with measurements of surface currents and fronts, provided insights into its development and retention. Interdisciplinary approaches shed light on the biophysical coupling underlying the persistence and horizontal transport of harmful algal blooms in productive marine environments.
Silvan Urs Goldenberg, Ulf Riebesell, Daniel Brüggemann, Gregor Börner, Michael Sswat, Arild Folkvord, Maria Couret, Synne Spjelkavik, Nicolás Sánchez, Cornelia Jaspers, and Marta Moyano
Biogeosciences, 21, 4521–4532, https://doi.org/10.5194/bg-21-4521-2024, https://doi.org/10.5194/bg-21-4521-2024, 2024
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Ocean alkalinity enhancement (OAE) is being evaluated as a carbon dioxide removal technology for climate change mitigation. With an experiment on species communities, we show that larval and juvenile fish can be resilient to the resulting perturbation of seawater. Fish may hence recruit successfully and continue to support fisheries' production in regions of OAE. Our findings help to establish an environmentally safe operating space for this ocean-based solution.
Thibauld M. Béjard, Andrés S. Rigual-Hernández, Javier P. Tarruella, José-Abel Flores, Anna Sanchez-Vidal, Irene Llamas-Cano, and Francisco J. Sierro
Biogeosciences, 21, 4051–4076, https://doi.org/10.5194/bg-21-4051-2024, https://doi.org/10.5194/bg-21-4051-2024, 2024
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The Mediterranean Sea is regarded as a climate change hotspot. Documenting the population of planktonic foraminifera is crucial. In the Sicily Channel, fluxes are higher during winter and positively linked with chlorophyll a concentration and cool temperatures. A comparison with other Mediterranean sites shows the transitional aspect of the studied zone. Finally, modern populations significantly differ from those in the sediment, highlighting a possible effect of environmental change.
Skye Yunshu Tian, Martin Langer, Moriaki Yasuhara, and Chih-Lin Wei
Biogeosciences, 21, 3523–3536, https://doi.org/10.5194/bg-21-3523-2024, https://doi.org/10.5194/bg-21-3523-2024, 2024
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Through the first large-scale study of meiobenthic ostracods from the diverse and productive reef ecosystem in the Zanzibar Archipelago, Tanzania, we found that the diversity and composition of ostracod assemblages as controlled by benthic habitats and human impacts were indicative of overall reef health, and we highlighted the usefulness of ostracods as a model proxy to monitor and understand the degradation of reef ecosystems from the coral-dominated phase to the algae-dominated phase.
Julien Richirt, Satoshi Okada, Yoshiyuki Ishitani, Katsuyuki Uematsu, Akihiro Tame, Kaya Oda, Noriyuki Isobe, Toyoho Ishimura, Masashi Tsuchiya, and Hidetaka Nomaki
Biogeosciences, 21, 3271–3288, https://doi.org/10.5194/bg-21-3271-2024, https://doi.org/10.5194/bg-21-3271-2024, 2024
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We report the first benthic foraminifera with a composite test (i.e. shell) made of opal, which coats the inner part of the calcitic layer. Using comprehensive techniques, we describe the morphology and the composition of this novel opal layer and provide evidence that the opal is precipitated by the foraminifera itself. We explore the potential precipitation process and function(s) of this composite test and further discuss the possible implications for palaeoceanographic reconstructions.
Said Mohamed Hashim, Beth Wangui Waweru, and Agnes Muthumbi
Biogeosciences, 21, 2995–3006, https://doi.org/10.5194/bg-21-2995-2024, https://doi.org/10.5194/bg-21-2995-2024, 2024
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The study investigates the impact of decreasing oxygen in the ocean on macrofaunal communities using the BUS as an example. It identifies distinct shifts in community composition and feeding guilds across oxygen zones, with nematodes dominating dysoxic areas. These findings underscore the complex responses of benthic organisms to oxygen gradients, crucial for understanding ecosystem dynamics in hypoxic environments and their implications for marine biodiversity and sustainability.
Tanguy Soulié, Francesca Vidussi, Justine Courboulès, Marie Heydon, Sébastien Mas, Florian Voron, Carolina Cantoni, Fabien Joux, and Behzad Mostajir
Biogeosciences, 21, 1887–1902, https://doi.org/10.5194/bg-21-1887-2024, https://doi.org/10.5194/bg-21-1887-2024, 2024
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Due to climate change, it is projected that extreme rainfall events, which bring terrestrial matter into coastal seas, will occur more frequently in the Mediterranean region. To test the effects of runoffs of terrestrial matter on plankton communities from Mediterranean coastal waters, an in situ mesocosm experiment was conducted. The simulated runoff affected key processes mediated by plankton, such as primary production and respiration, suggesting major consequences of such events.
Chueh-Chen Tung, Yu-Shih Lin, Jian-Xiang Liao, Tzu-Hsuan Tu, James T. Liu, Li-Hung Lin, Pei-Ling Wang, and Chih-Lin Wei
Biogeosciences, 21, 1729–1756, https://doi.org/10.5194/bg-21-1729-2024, https://doi.org/10.5194/bg-21-1729-2024, 2024
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This study contrasts seabed food webs between a river-fed, high-energy canyon and the nearby slope. We show higher organic carbon (OC) flows through the canyon than the slope. Bacteria dominated the canyon, while seabed fauna contributed more to the slope food web. Due to frequent perturbation, the canyon had a lower faunal stock and OC recycling. Only 4 % of the seabed OC flux enters the canyon food web, suggesting a significant role of the river-fed canyon in transporting OC to the deep sea.
Joost de Vries, Fanny Monteiro, Gerald Langer, Colin Brownlee, and Glen Wheeler
Biogeosciences, 21, 1707–1727, https://doi.org/10.5194/bg-21-1707-2024, https://doi.org/10.5194/bg-21-1707-2024, 2024
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Calcifying phytoplankton (coccolithophores) utilize a life cycle in which they can grow and divide into two different phases. These two phases (HET and HOL) vary in terms of their physiology and distributions, with many unknowns about what the key differences are. Using a combination of lab experiments and model simulations, we find that nutrient storage is a critical difference between the two phases and that this difference allows them to inhabit different nitrogen input regimes.
Theodor Kindeberg, Karl Michael Attard, Jana Hüller, Julia Müller, Cintia Organo Quintana, and Eduardo Infantes
Biogeosciences, 21, 1685–1705, https://doi.org/10.5194/bg-21-1685-2024, https://doi.org/10.5194/bg-21-1685-2024, 2024
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Seagrass meadows are hotspots for biodiversity and productivity, and planting seagrass is proposed as a tool for mitigating biodiversity loss and climate change. We assessed seagrass planted in different years and found that benthic oxygen and carbon fluxes increased as the seabed developed from bare sediments to a mature seagrass meadow. This increase was partly linked to the diversity of colonizing algae which increased the light-use efficiency of the seagrass meadow community.
Anna-Selma van der Kaaden, Sandra R. Maier, Siluo Chen, Laurence H. De Clippele, Evert de Froe, Theo Gerkema, Johan van de Koppel, Furu Mienis, Christian Mohn, Max Rietkerk, Karline Soetaert, and Dick van Oevelen
Biogeosciences, 21, 973–992, https://doi.org/10.5194/bg-21-973-2024, https://doi.org/10.5194/bg-21-973-2024, 2024
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Combining hydrodynamic simulations and annotated videos, we separated which hydrodynamic variables that determine reef cover are engineered by cold-water corals and which are not. Around coral mounds, hydrodynamic zones seem to create a typical reef zonation, restricting corals from moving deeper (the expected response to climate warming). But non-engineered downward velocities in winter (e.g. deep winter mixing) seem more important for coral reef growth than coral engineering.
Xiaoke Xin, Giulia Faucher, and Ulf Riebesell
Biogeosciences, 21, 761–772, https://doi.org/10.5194/bg-21-761-2024, https://doi.org/10.5194/bg-21-761-2024, 2024
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Ocean alkalinity enhancement (OAE) is a promising approach to remove CO2 by accelerating natural rock weathering. However, some of the alkaline substances contain trace metals which could be toxic to marine life. By exposing three representative phytoplankton species to Ni released from alkaline materials, we observed varying responses of phytoplankton to nickel concentrations, suggesting caution should be taken and toxic thresholds should be avoided in OAE with Ni-rich materials.
Olmo Miguez-Salas, Angelika Brandt, Henry Knauber, and Torben Riehl
Biogeosciences, 21, 641–655, https://doi.org/10.5194/bg-21-641-2024, https://doi.org/10.5194/bg-21-641-2024, 2024
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In the deep sea, the interaction between benthic fauna (tracemakers) and substrate can be preserved as traces (i.e. lebensspuren), which are common features of seafloor landscapes, rendering them promising proxies for inferring biodiversity from marine images. No general correlation was observed between traces and benthic fauna. However, a local correlation was observed between specific stations depending on unknown tracemakers, tracemaker behaviour, and lebensspuren morphotypes.
Cale A. Miller, Pierre Urrutti, Jean-Pierre Gattuso, Steeve Comeau, Anaïs Lebrun, Samir Alliouane, Robert W. Schlegel, and Frédéric Gazeau
Biogeosciences, 21, 315–333, https://doi.org/10.5194/bg-21-315-2024, https://doi.org/10.5194/bg-21-315-2024, 2024
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This work describes an experimental system that can replicate and manipulate environmental conditions in marine or aquatic systems. Here, we show how the temperature and salinity of seawater delivered from a fjord is manipulated to experimental tanks on land. By constantly monitoring temperature and salinity in each tank via a computer program, the system continuously adjusts automated flow valves to ensure the seawater in each tank matches the targeted experimental conditions.
Rachel A. Kruft Welton, George Hoppit, Daniela N. Schmidt, James D. Witts, and Benjamin C. Moon
Biogeosciences, 21, 223–239, https://doi.org/10.5194/bg-21-223-2024, https://doi.org/10.5194/bg-21-223-2024, 2024
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We conducted a meta-analysis of known experimental literature examining how marine bivalve growth rates respond to climate change. Growth is usually negatively impacted by climate change. Bivalve eggs/larva are generally more vulnerable than either juveniles or adults. Available data on the bivalve response to climate stressors are biased towards early growth stages (commercially important in the Global North), and many families have only single experiments examining climate change impacts.
Vincent Mouchi, Christophe Pecheyran, Fanny Claverie, Cécile Cathalot, Marjolaine Matabos, Yoan Germain, Olivier Rouxel, Didier Jollivet, Thomas Broquet, and Thierry Comtet
Biogeosciences, 21, 145–160, https://doi.org/10.5194/bg-21-145-2024, https://doi.org/10.5194/bg-21-145-2024, 2024
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The impact of deep-sea mining will depend critically on the ability of larval dispersal of hydrothermal mollusks to connect and replenish natural populations. However, assessing connectivity is extremely challenging, especially in the deep sea. Here, we investigate the potential of using the chemical composition of larval shells to discriminate larval origins between multiple hydrothermal sites in the southwest Pacific. Our results confirm that this method can be applied with high accuracy.
Anna-Marie Winter, Nadezda Vasilyeva, and Artem Vladimirov
Biogeosciences, 20, 3683–3716, https://doi.org/10.5194/bg-20-3683-2023, https://doi.org/10.5194/bg-20-3683-2023, 2023
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There is an increasing number of fish in poor state, and many do not recover, even when fishing pressure is ceased. An Allee effect can hinder population recovery because it suppresses the fish's productivity at low abundance. With a model fitted to 17 Atlantic cod stocks, we find that ocean warming and fishing can cause an Allee effect. If present, the Allee effect hinders fish recovery. This shows that Allee effects are dynamic, not uncommon, and calls for precautionary management measures.
Afrah Alothman, Daffne López-Sandoval, Carlos M. Duarte, and Susana Agustí
Biogeosciences, 20, 3613–3624, https://doi.org/10.5194/bg-20-3613-2023, https://doi.org/10.5194/bg-20-3613-2023, 2023
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This study investigates bacterial dissolved inorganic carbon (DIC) fixation in the Red Sea, an oligotrophic ecosystem, using stable-isotope labeling and spectroscopy. The research reveals that bacterial DIC fixation significantly contributes to total DIC fixation, in the surface and deep water. The study demonstrates that as primary production decreases, the role of bacterial DIC fixation increases, emphasizing its importance with photosynthesis in estimating oceanic carbon dioxide production.
Arianna Zampollo, Thomas Cornulier, Rory O'Hara Murray, Jacqueline Fiona Tweddle, James Dunning, and Beth E. Scott
Biogeosciences, 20, 3593–3611, https://doi.org/10.5194/bg-20-3593-2023, https://doi.org/10.5194/bg-20-3593-2023, 2023
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This paper highlights the use of the bottom mixed layer depth (BMLD: depth between the end of the pycnocline and the mixed layer below) to investigate subsurface Chlorophyll a (a proxy of primary production) in temperate stratified shelf waters. The strict correlation between subsurface Chl a and BMLD becomes relevant in shelf-productive waters where multiple stressors (e.g. offshore infrastructure) will change the stratification--mixing balance and related carbon fluxes.
Marco Fusi, Sylvain Rigaud, Giovanna Guadagnin, Alberto Barausse, Ramona Marasco, Daniele Daffonchio, Julie Régis, Louison Huchet, Capucine Camin, Laura Pettit, Cristina Vina-Herbon, and Folco Giomi
Biogeosciences, 20, 3509–3521, https://doi.org/10.5194/bg-20-3509-2023, https://doi.org/10.5194/bg-20-3509-2023, 2023
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Oxygen availability in marine water and freshwater is very variable at daily and seasonal scales. The dynamic nature of oxygen fluctuations has important consequences for animal and microbe physiology and ecology, yet it is not fully understood. In this paper, we showed the heterogeneous nature of the aquatic oxygen landscape, which we defined here as the
oxyscape, and we addressed the importance of considering the oxyscape in the modelling and managing of aquatic ecosystems.
Anne L. Morée, Tayler M. Clarke, William W. L. Cheung, and Thomas L. Frölicher
Biogeosciences, 20, 2425–2454, https://doi.org/10.5194/bg-20-2425-2023, https://doi.org/10.5194/bg-20-2425-2023, 2023
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Ocean temperature and oxygen shape marine habitats together with species’ characteristics. We calculated the impacts of projected 21st-century warming and oxygen loss on the contemporary habitat volume of 47 marine species and described the drivers of these impacts. Most species lose less than 5 % of their habitat at 2 °C of global warming, but some species incur losses 2–3 times greater than that. We also calculate which species may be most vulnerable to climate change and why this is the case.
Markus A. Min, David M. Needham, Sebastian Sudek, Nathan Kobun Truelove, Kathleen J. Pitz, Gabriela M. Chavez, Camille Poirier, Bente Gardeler, Elisabeth von der Esch, Andrea Ludwig, Ulf Riebesell, Alexandra Z. Worden, and Francisco P. Chavez
Biogeosciences, 20, 1277–1298, https://doi.org/10.5194/bg-20-1277-2023, https://doi.org/10.5194/bg-20-1277-2023, 2023
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Emerging molecular methods provide new ways of understanding how marine communities respond to changes in ocean conditions. Here, environmental DNA was used to track the temporal evolution of biological communities in the Peruvian coastal upwelling system and in an adjacent enclosure where upwelling was simulated. We found that the two communities quickly diverged, with the open ocean being one found during upwelling and the enclosure evolving to one found under stratified conditions.
Wojciech Majewski, Witold Szczuciński, and Andrew J. Gooday
Biogeosciences, 20, 523–544, https://doi.org/10.5194/bg-20-523-2023, https://doi.org/10.5194/bg-20-523-2023, 2023
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We studied foraminifera living in the fjords of South Georgia, a sub-Antarctic island sensitive to climate change. As conditions in water and on the seafloor vary, different associations of these microorganisms dominate far inside, in the middle, and near fjord openings. Assemblages in inner and middle parts of fjords are specific to South Georgia, but they may become widespread with anticipated warming. These results are important for interpretating fossil records and monitoring future change.
Allanah Joy Paul, Lennart Thomas Bach, Javier Arístegui, Elisabeth von der Esch, Nauzet Hernández-Hernández, Jonna Piiparinen, Laura Ramajo, Kristian Spilling, and Ulf Riebesell
Biogeosciences, 19, 5911–5926, https://doi.org/10.5194/bg-19-5911-2022, https://doi.org/10.5194/bg-19-5911-2022, 2022
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We investigated how different deep water chemistry and biology modulate the response of surface phytoplankton communities to upwelling in the Peruvian coastal zone. Our results show that the most influential drivers were the ratio of inorganic nutrients (N : P) and the microbial community present in upwelling source water. These led to unexpected and variable development in the phytoplankton assemblage that could not be predicted by the amount of inorganic nutrients alone.
Hanna M. Kauko, Philipp Assmy, Ilka Peeken, Magdalena Różańska-Pluta, Józef M. Wiktor, Gunnar Bratbak, Asmita Singh, Thomas J. Ryan-Keogh, and Sebastien Moreau
Biogeosciences, 19, 5449–5482, https://doi.org/10.5194/bg-19-5449-2022, https://doi.org/10.5194/bg-19-5449-2022, 2022
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This article studies phytoplankton (microscopic
plantsin the ocean capable of photosynthesis) in Kong Håkon VII Hav in the Southern Ocean. Different species play different roles in the ecosystem, and it is therefore important to assess the species composition. We observed that phytoplankton blooms in this area are formed by large diatoms with strong silica armors, which can lead to high silica (and sometimes carbon) export to depth and be important prey for krill.
Chloe Carbonne, Steeve Comeau, Phoebe T. W. Chan, Keyla Plichon, Jean-Pierre Gattuso, and Núria Teixidó
Biogeosciences, 19, 4767–4777, https://doi.org/10.5194/bg-19-4767-2022, https://doi.org/10.5194/bg-19-4767-2022, 2022
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For the first time, our study highlights the synergistic effects of a 9-month warming and acidification combined stress on the early life stages of a Mediterranean azooxanthellate coral, Astroides calycularis. Our results predict a decrease in dispersion, settlement, post-settlement linear extention, budding and survival under future global change and that larvae and recruits of A. calycularis are stages of interest for this Mediterranean coral resistance, resilience and conservation.
Iris E. Hendriks, Anna Escolano-Moltó, Susana Flecha, Raquel Vaquer-Sunyer, Marlene Wesselmann, and Núria Marbà
Biogeosciences, 19, 4619–4637, https://doi.org/10.5194/bg-19-4619-2022, https://doi.org/10.5194/bg-19-4619-2022, 2022
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Seagrasses are marine plants with the capacity to act as carbon sinks due to their high primary productivity, using carbon for growth. This capacity can play a key role in climate change mitigation. We compiled and published data showing that two Mediterranean seagrass species have different metabolic rates, while the study method influences the rates of the measurements. Most communities act as carbon sinks, while the western basin might be more productive than the eastern Mediterranean.
Raúl Tapia, Sze Ling Ho, Hui-Yu Wang, Jeroen Groeneveld, and Mahyar Mohtadi
Biogeosciences, 19, 3185–3208, https://doi.org/10.5194/bg-19-3185-2022, https://doi.org/10.5194/bg-19-3185-2022, 2022
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We report census counts of planktic foraminifera in depth-stratified plankton net samples off Indonesia. Our results show that the vertical distribution of foraminifera species routinely used in paleoceanographic reconstructions varies in hydrographically distinct regions, likely in response to food availability. Consequently, the thermal gradient based on mixed layer and thermocline dwellers also differs for these regions, suggesting potential implications for paleoceanographic reconstructions.
Ricardo González-Gil, Neil S. Banas, Eileen Bresnan, and Michael R. Heath
Biogeosciences, 19, 2417–2426, https://doi.org/10.5194/bg-19-2417-2022, https://doi.org/10.5194/bg-19-2417-2022, 2022
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In oceanic waters, the accumulation of phytoplankton biomass in winter, when light still limits growth, is attributed to a decrease in grazing as the mixed layer deepens. However, in coastal areas, it is not clear whether winter biomass can accumulate without this deepening. Using 21 years of weekly data, we found that in the Scottish coastal North Sea, the seasonal increase in light availability triggers the accumulation of phytoplankton biomass in winter, when light limitation is strongest.
Birgit Koehler, Mårten Erlandsson, Martin Karlsson, and Lena Bergström
Biogeosciences, 19, 2295–2312, https://doi.org/10.5194/bg-19-2295-2022, https://doi.org/10.5194/bg-19-2295-2022, 2022
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Understanding species richness patterns remains a challenge for biodiversity management. We estimated fish species richness over a coastal salinity gradient (3–32) with a method that allowed comparing data from various sources. Species richness was 3-fold higher at high vs. low salinity, and salinity influenced species’ habitat preference, mobility and feeding type. If climate change causes upper-layer freshening of the Baltic Sea, further shifts along the identified patterns may be expected.
Uri Obolski, Thomas Wichard, Alvaro Israel, Alexander Golberg, and Alexander Liberzon
Biogeosciences, 19, 2263–2271, https://doi.org/10.5194/bg-19-2263-2022, https://doi.org/10.5194/bg-19-2263-2022, 2022
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The algal genus Ulva plays a major role in coastal ecosystems worldwide and is a promising prospect as an seagriculture crop. A substantial hindrance to cultivating Ulva arises from sudden sporulation, leading to biomass loss. This process is not yet well understood. Here, we characterize the dynamics of Ulva growth, considering the potential impact of sporulation inhibitors, using a mathematical model. Our findings are an essential step towards understanding the dynamics of Ulva growth.
Emanuela Fanelli, Samuele Menicucci, Sara Malavolti, Andrea De Felice, and Iole Leonori
Biogeosciences, 19, 1833–1851, https://doi.org/10.5194/bg-19-1833-2022, https://doi.org/10.5194/bg-19-1833-2022, 2022
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Zooplankton play a key role in marine ecosystems, forming the base of the marine food web and a link between primary producers and higher-order consumers, such as fish. This aspect is crucial in the Adriatic basin, one of the most productive and overexploited areas of the Mediterranean Sea. A better understanding of community and food web structure and their response to water mass changes is essential under a global warming scenario, as zooplankton are sensitive to climate change.
Masaya Yoshikai, Takashi Nakamura, Rempei Suwa, Sahadev Sharma, Rene Rollon, Jun Yasuoka, Ryohei Egawa, and Kazuo Nadaoka
Biogeosciences, 19, 1813–1832, https://doi.org/10.5194/bg-19-1813-2022, https://doi.org/10.5194/bg-19-1813-2022, 2022
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This study presents a new individual-based vegetation model to investigate salinity control on mangrove productivity. The model incorporates plant hydraulics and tree competition and predicts unique and complex patterns of mangrove forest structures that vary across soil salinity gradients. The presented model does not hold an empirical expression of salinity influence on productivity and thus may provide a better understanding of mangrove forest dynamics in future climate change.
Coulson A. Lantz, William Leggat, Jessica L. Bergman, Alexander Fordyce, Charlotte Page, Thomas Mesaglio, and Tracy D. Ainsworth
Biogeosciences, 19, 891–906, https://doi.org/10.5194/bg-19-891-2022, https://doi.org/10.5194/bg-19-891-2022, 2022
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Coral bleaching events continue to drive the degradation of coral reefs worldwide. In this study we measured rates of daytime coral reef community calcification and photosynthesis during a reef-wide bleaching event. Despite a measured decline in coral health across several taxa, there was no change in overall daytime community calcification and photosynthesis. These findings highlight potential limitations of these community-level metrics to reflect actual changes in coral health.
Hyewon Heather Kim, Jeff S. Bowman, Ya-Wei Luo, Hugh W. Ducklow, Oscar M. Schofield, Deborah K. Steinberg, and Scott C. Doney
Biogeosciences, 19, 117–136, https://doi.org/10.5194/bg-19-117-2022, https://doi.org/10.5194/bg-19-117-2022, 2022
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Heterotrophic marine bacteria are tiny organisms responsible for taking up organic matter in the ocean. Using a modeling approach, this study shows that characteristics (taxonomy and physiology) of bacteria are associated with a subset of ecological processes in the coastal West Antarctic Peninsula region, a system susceptible to global climate change. This study also suggests that bacteria will become more active, in particular large-sized cells, in response to changing climates in the region.
Alice E. Webb, Didier M. de Bakker, Karline Soetaert, Tamara da Costa, Steven M. A. C. van Heuven, Fleur C. van Duyl, Gert-Jan Reichart, and Lennart J. de Nooijer
Biogeosciences, 18, 6501–6516, https://doi.org/10.5194/bg-18-6501-2021, https://doi.org/10.5194/bg-18-6501-2021, 2021
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The biogeochemical behaviour of shallow reef communities is quantified to better understand the impact of habitat degradation and species composition shifts on reef functioning. The reef communities investigated barely support reef functions that are usually ascribed to conventional coral reefs, and the overall biogeochemical behaviour is found to be similar regardless of substrate type. This suggests a decrease in functional diversity which may therefore limit services provided by this reef.
Emmanuel Devred, Andrea Hilborn, and Cornelia Elizabeth den Heyer
Biogeosciences, 18, 6115–6132, https://doi.org/10.5194/bg-18-6115-2021, https://doi.org/10.5194/bg-18-6115-2021, 2021
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A theoretical model of grey seal seasonal abundance on Sable Island (SI) coupled with chlorophyll-a concentration [chl-a] measured by satellite revealed the impact of seal nitrogen fertilization on the surrounding waters of SI, Canada. The increase in seals from about 100 000 in 2003 to about 360 000 in 2018 during the breeding season is consistent with an increase in [chl-a] leeward of SI. The increase in seal abundance explains 8 % of the [chl-a] increase.
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Short summary
Cultured at in situ high-pressure conditions Cibicides and Cibicidoides taxa develop lasting ectoplasmic structures that cannot be retracted or resorbed. An ectoplasmic envelope surrounds their test and may protect the shell, e.g. versus carbonate aggressive bottom water conditions. Ectoplasmic roots likely anchor the specimens in areas of strong bottom water currents, trees enable them to elevate themselves above ground, and twigs stabilize and guide the retractable pseudopodial network.
Cultured at in situ high-pressure conditions Cibicides and Cibicidoides taxa develop lasting...
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