Articles | Volume 22, issue 1
https://doi.org/10.5194/os-22-403-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/os-22-403-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Phytoplankton blooms affect microscale differences of oxygen and temperature across the sea surface microlayer
Carsten Rauch
CORRESPONDING AUTHOR
Center for Marine Sensors (ZfMarS), Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstraße 114–118, 26129 Oldenburg, Germany
Lisa Deyle
Center for Marine Sensors (ZfMarS), Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstraße 114–118, 26129 Oldenburg, Germany
Leonie Jaeger
Center for Marine Sensors (ZfMarS), Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstraße 114–118, 26129 Oldenburg, Germany
Edgar Fernando Cortés-Espinoza
Center for Marine Sensors (ZfMarS), Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstraße 114–118, 26129 Oldenburg, Germany
Mariana Ribas-Ribas
Center for Marine Sensors (ZfMarS), Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstraße 114–118, 26129 Oldenburg, Germany
Josefine Karnatz
GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1–3, 24148 Kiel, Germany
Anja Engel
GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1–3, 24148 Kiel, Germany
Oliver Wurl
Center for Marine Sensors (ZfMarS), Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstraße 114–118, 26129 Oldenburg, Germany
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Lin Yang, Bin Yang, Jing Zhang, Anja Engel, and Gui-Peng Yang
Biogeosciences, 23, 1261–1278, https://doi.org/10.5194/bg-23-1261-2026, https://doi.org/10.5194/bg-23-1261-2026, 2026
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Carbon monoxide (CO), chromophoric dissolved organic matter (CDOM), and fluorescent dissolved organic matter (FDOM) were more frequently enriched in the higher temperature and salinity off-shore regions. Marine-humic like CDOM tends to inhibit the sea-to-air flux of CO in the sea-surface microlayer (SML). The enrichment and photochemical process of CO in the SML were more active during the daytime. The photochemical production and microbial consumption rates of CO in the SML were more active than in the subsurface layer (SSW).
Lina A. Holthusen, Hermann W. Bange, Thomas H. Badewien, Julia C. Muchowski, Tina Santl-Temkiv, Jennie Spicker Schmidt, Oliver Wurl, and Damian L. Arévalo-Martínez
The Cryosphere, 20, 535–550, https://doi.org/10.5194/tc-20-535-2026, https://doi.org/10.5194/tc-20-535-2026, 2026
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In spring 2023, in the Fram Strait, we investigated the near-surface distribution of the greenhouse gases methane and nitrous oxide in open leads and under sea ice to address the lack of observations in the Arctic Ocean. The study area acted as a source for both gases, and the onset of sea ice melt affected their concentrations and emissions. Surface-active substances accumulated in the sea-surface microlayer of open leads during an algal bloom, potentially attenuating greenhouse gas emissions.
Falko Asmussen-Schäfer, Mariana Ribas-Ribas, Oliver Wurl, and Gernot Friedrichs
EGUsphere, https://doi.org/10.5194/egusphere-2025-5276, https://doi.org/10.5194/egusphere-2025-5276, 2026
This preprint is open for discussion and under review for Biogeosciences (BG).
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We developed a way to quantify how molecules accumulate at the ocean surface on a nanometer scale. Using laser spectroscopy and electrochemical methods, we measured how densely these molecular films cover the water surface. Such single-molecule-thick layers can greatly influence gas exchange between the ocean and the atmosphere. By comparing our results with existing data sets, we produced a first global estimate of potential film coverage.
Yuanxu Dong, Christa A. Marandino, Ryo Dobashi, David Ho, Gregor Rehder, Henry C. Bittig, Josefine Karnatz, Bita Sabbaghzadeh, Helen Czerski, and Anja Engel
EGUsphere, https://doi.org/10.5194/egusphere-2025-6095, https://doi.org/10.5194/egusphere-2025-6095, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Air-sea gas exchange regulates the Earth's climate. However, the kinetic exchange process only uses wind speed to describe, neglecting other drivers. In this study, we investigate how fetch and natural surfactants modulate the air-sea carbon dioxide exchange. Measurements from the central Baltic Sea show that limited fetch and elevated surfactants significantly suppress this exchange. A new parameterization is provided, improving regional carbon budgets and evaluations of climate solutions.
Jasper Zöbelein, Shubham Sawle, Gernot Friedrichs, Mariana Ribas-Ribas, Carola Lehners, Katharina Paetz, Maximilian Pflaum, and Hannelore Waska
EGUsphere, https://doi.org/10.5194/egusphere-2025-6563, https://doi.org/10.5194/egusphere-2025-6563, 2026
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The ocean is glazed with a one-millimetre biofilm that controls the flow of gases and energy from the atmosphere. To investigate how this film forms, we cultivated microscopic algae in a tank under controlled, windless conditions. Our results show that carbohydrates released by these algae rise to the surface, forming "carbo-slicks" that create this gel-like layer. This demonstrates that biological production is a key driver of the sea surface, which is crucial for understanding carbon exchange.
Ander López-Puertas, Oliver Wurl, Sanja Frka, and Mariana Ribas-Ribas
Ocean Sci., 21, 3471–3485, https://doi.org/10.5194/os-21-3471-2025, https://doi.org/10.5194/os-21-3471-2025, 2025
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We studied how daily cycles affect inorganic carbon variables in the ocean's surface microlayer. Using data from three full days and nights off the Croatian coast, we found that thermohaline properties and key indicators like pH and pCO₂ change significantly from day to night. Ignoring nighttime conditions may lead to global carbon budget errors and highlights the need for continuous ocean observations.
Riaz Bibi, Mariana Ribas-Ribas, Leonie Jaeger, Carola Lehners, Lisa Gassen, Edgar Fernando Cortés-Espinoza, Jochen Wollschläger, Claudia Thölen, Hannelore Waska, Jasper Zöbelein, Thorsten Brinkhoff, Isha Athale, Rüdiger Röttgers, Michael Novak, Anja Engel, Theresa Barthelmeß, Josefine Karnatz, Thomas Reinthaler, Dmytro Spriahailo, Gernot Friedrichs, Falko Asmussen Schäfer, and Oliver Wurl
Biogeosciences, 22, 7563–7589, https://doi.org/10.5194/bg-22-7563-2025, https://doi.org/10.5194/bg-22-7563-2025, 2025
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A multidisciplinary mesocosm study was conducted to investigate biogeochemical processes and their relationships in the sea-surface microlayer and underlying water during an induced phytoplankton bloom. Phytoplankton-derived organic matter, fuelled microbial activity and biofilm formation, supporting high bacterial abundance. Distinct temporal patterns in biogeochemical parameters and greater variability in the sea-surface microlayer highlight its influence on air–sea interactions.
Josefine Karnatz, Theresa Barthelmeß, Bita Sabbaghzadeh, and Anja Engel
EGUsphere, https://doi.org/10.5194/egusphere-2025-5385, https://doi.org/10.5194/egusphere-2025-5385, 2025
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Cyanobacteria form massive summer blooms in the Baltic Sea that release organic compounds to the ocean’s surface. By analyzing the thin boundary layer between ocean and atmosphere, this study shows that cyanobacteria influence the molecular composition and surface properties of the sea surface, increasing surfactants that may reduce gas exchange. The findings provide new insight into how future cyanobacteria blooms could affect air-sea interactions and climate-related processes.
Lea Lange, Dennis Booge, Hendrik Feil, Josefine Karnatz, Ina Stoltenberg, Hermann W. Bange, and Christa A. Marandino
EGUsphere, https://doi.org/10.5194/egusphere-2025-5361, https://doi.org/10.5194/egusphere-2025-5361, 2025
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Many gases formed and destroyed in the ocean influence climate and air quality, with evidence that these processes also happen in the skin of the ocean. Studies of this thin upper layer use specialized sampling equipment, which is known to cause losses of the gases. We performed lab experiments to quantify these losses for three gases and found that 13 % remain after sampling. With further tests, our results can be used to obtain reliable gas measurements in the field, which have been elusive.
Edgar Fernando Cortés-Espinoza, Alisa Wüst, Ander Lopéz-Puertas, Oliver Wurl, José Martín Hernández-Ayón, Hannelore Waska, and Mariana Ribas-Ribas
EGUsphere, https://doi.org/10.5194/egusphere-2025-5265, https://doi.org/10.5194/egusphere-2025-5265, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
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In a mesocosm experiment, we measured carbon system variables to examine how organic matter accumulation increases organic alkalinity and alters seawater pH in the sea-surface microlayer and underlying water during an induced phytoplankton bloom. Organic alkalinity was consistently higher in the sea-surface microlayer, and during bloom peak its pH effect extended into the underlying water, reducing and sometimes reversing surface–subsurface pH differences.
Anja Engel, Gernot Friedrichs, Kerstin Krall, and Bernd Jähne
EGUsphere, https://doi.org/10.5194/egusphere-2025-5375, https://doi.org/10.5194/egusphere-2025-5375, 2025
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We investigated how organic molecules in the ocean’s surface layer accumulate and respond to wind. Using a large wind-wave tank filled with seawater, we found that natural molecules produced by marine microbes gather at the surface under light winds, slowing the exchange of gases such as carbon dioxide. When winds increase, this layer rapidly breaks down. These findings suggest that marine life can influence how the ocean and atmosphere interact, particularly in calm conditions.
Lisa Gassen, Samuel M. Ayim, Leonie Jaeger, Jens Meyerjürgens, Mariana Ribas-Ribas, and Oliver Wurl
Ocean Sci., 21, 2787–2804, https://doi.org/10.5194/os-21-2787-2025, https://doi.org/10.5194/os-21-2787-2025, 2025
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This study investigates how abrupt weather changes, such as shifts in air temperature, wind speed and precipitation, impact temperature and salinity in the ocean’s skin layer (upper first millimetre). Two events in the harbour of Bremerhaven and one event in the North Sea revealed that the skin layer reacts instantly, with greater temperature changes than those at a depth of 100 cm, underscoring its key role in air-sea interactions and climate dynamics.
Michelle Albinus, Thomas H. Badewien, Lisa Gassen, Oliver Wurl, and Jens Meyerjürgens
EGUsphere, https://doi.org/10.5194/egusphere-2025-4953, https://doi.org/10.5194/egusphere-2025-4953, 2025
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This study reveals how short-lived and narrow freshwater-driven ocean "light" filaments form and evolve within tidal fronts. Using multi-platform in situ observations, it is shown that these submesoscale features can rapidly form and reshape in near-surface waters, influencing how energy and heat alter just below the ocean-atmosphere interface.
Amavi N. Silva, Surandokht Nikzad, Theresa Barthelmeß, Anja Engel, Hartmut Hermann, Manuela van Pinxteren, Kai Wirtz, Oliver Wurl, and Markus Schartau
EGUsphere, https://doi.org/10.5194/egusphere-2025-4050, https://doi.org/10.5194/egusphere-2025-4050, 2025
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We conducted the first meta-analysis combining marine and freshwater studies to understand organic matter enrichment in the surface microlayer. Nitrogen-rich, particulate compounds are often enriched, with patterns varying by multiple factors. We recommend tracking both absolute concentrations and normalized enrichment patterns to better assess ecological conditions. Our study also introduces improved statistical methods for analyzing and comparing surface microlayer data.
Anisbel Leon-Marcos, Moritz Zeising, Manuela van Pinxteren, Sebastian Zeppenfeld, Astrid Bracher, Elena Barbaro, Anja Engel, Matteo Feltracco, Ina Tegen, and Bernd Heinold
Geosci. Model Dev., 18, 4183–4213, https://doi.org/10.5194/gmd-18-4183-2025, https://doi.org/10.5194/gmd-18-4183-2025, 2025
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This study represents the primary marine organic aerosol (PMOA) emissions, focusing on their sea–atmosphere transfer. Using the FESOM2.1–REcoM3 model, concentrations of key organic biomolecules were estimated and integrated into the ECHAM6.3–HAM2.3 aerosol–climate model. Results highlight the influence of marine biological activity and surface winds on PMOA emissions, with reasonably good agreement with observations improving aerosol representation in the southern oceans.
Lisa Deyle, Thomas H. Badewien, Oliver Wurl, and Jens Meyerjürgens
Earth Syst. Sci. Data, 16, 2099–2112, https://doi.org/10.5194/essd-16-2099-2024, https://doi.org/10.5194/essd-16-2099-2024, 2024
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A dataset from the North Sea of 85 surface drifters from 2017–2021 is presented. Surface drifters enable the analysis of ocean currents by determining the velocities of surface currents and tidal effects. The entire North Sea has not been studied using drifters before, but the analysis of ocean currents is essential, e.g., to understand the pathways of plastic. The results show that there are strong tidal effects in the shallow North Sea area and strong surface currents in the deep areas.
Karine Sellegri, Theresa Barthelmeß, Jonathan Trueblood, Antonia Cristi, Evelyn Freney, Clémence Rose, Neill Barr, Mike Harvey, Karl Safi, Stacy Deppeler, Karen Thompson, Wayne Dillon, Anja Engel, and Cliff Law
Atmos. Chem. Phys., 23, 12949–12964, https://doi.org/10.5194/acp-23-12949-2023, https://doi.org/10.5194/acp-23-12949-2023, 2023
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The amount of sea spray emitted to the atmosphere depends on the ocean temperature, but this dependency is not well understood, especially when ocean biology is involved. In this study, we show that sea spray emissions are increased by up to a factor of 4 at low seawater temperatures compared to moderate temperatures, and we quantify the temperature dependence as a function of the ocean biogeochemistry.
Manon Rocco, Erin Dunne, Alexia Saint-Macary, Maija Peltola, Theresa Barthelmeß, Neill Barr, Karl Safi, Andrew Marriner, Stacy Deppeler, James Harnwell, Anja Engel, Aurélie Colomb, Alfonso Saiz-Lopez, Mike Harvey, Cliff S. Law, and Karine Sellegri
EGUsphere, https://doi.org/10.5194/egusphere-2023-516, https://doi.org/10.5194/egusphere-2023-516, 2023
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During the Sea2cloud campaign in the Southern Pacific Ocean, we measured air-sea emissions from phytopankton of two key atmospheric compounds: DMS and MeSH. These compounds are well-known to play a great role in atmospheric chemistry and climate. We see in this paper that these compounds are most emited by the nanophytoplankton population. We provide here parameters for climate models to predict future trends of the emissions of these compounds and their roles and impacts on the global warming.
Lin Yang, Jing Zhang, Anja Engel, and Gui-Peng Yang
Biogeosciences, 19, 5251–5268, https://doi.org/10.5194/bg-19-5251-2022, https://doi.org/10.5194/bg-19-5251-2022, 2022
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Enrichment factors of dissolved organic matter (DOM) in the eastern marginal seas of China exhibited a significant spatio-temporal variation. Photochemical and enrichment processes co-regulated DOM enrichment in the sea-surface microlayer (SML). Autochthonous DOM was more frequently enriched in the SML than terrestrial DOM. DOM in the sub-surface water exhibited higher aromaticity than that in the SML.
Quentin Devresse, Kevin W. Becker, Arne Bendinger, Johannes Hahn, and Anja Engel
Biogeosciences, 19, 5199–5219, https://doi.org/10.5194/bg-19-5199-2022, https://doi.org/10.5194/bg-19-5199-2022, 2022
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Eddies are ubiquitous in the ocean and alter physical, chemical, and biological processes. However, how they affect organic carbon production and consumption is largely unknown. Here we show how an eddy triggers a cascade effect on biomass production and metabolic activities of phyto- and bacterioplankton. Our results may contribute to the improvement of biogeochemical models used to estimate carbon fluxes in the ocean.
Theresa Barthelmeß and Anja Engel
Biogeosciences, 19, 4965–4992, https://doi.org/10.5194/bg-19-4965-2022, https://doi.org/10.5194/bg-19-4965-2022, 2022
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Greenhouse gases released by human activity cause a global rise in mean temperatures. While scientists can predict how much of these gases accumulate in the atmosphere based on not only human-derived sources but also oceanic sinks, it is rather difficult to predict the major influence of coastal ecosystems. We provide a detailed study on the occurrence, composition, and controls of substances that suppress gas exchange. We thus help to determine what controls coastal greenhouse gas fluxes.
Manuela van Pinxteren, Tiera-Brandy Robinson, Sebastian Zeppenfeld, Xianda Gong, Enno Bahlmann, Khanneh Wadinga Fomba, Nadja Triesch, Frank Stratmann, Oliver Wurl, Anja Engel, Heike Wex, and Hartmut Herrmann
Atmos. Chem. Phys., 22, 5725–5742, https://doi.org/10.5194/acp-22-5725-2022, https://doi.org/10.5194/acp-22-5725-2022, 2022
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A class of marine particles (transparent exopolymer particles, TEPs) that is ubiquitously found in the world oceans was measured for the first time in ambient marine aerosol particles and marine cloud waters in the tropical Atlantic Ocean. TEPs are likely to have good properties for influencing clouds. We show that TEPs are transferred from the ocean to the marine atmosphere via sea-spray formation and our results suggest that they can also form directly in aerosol particles and in cloud water.
France Van Wambeke, Vincent Taillandier, Karine Desboeufs, Elvira Pulido-Villena, Julie Dinasquet, Anja Engel, Emilio Marañón, Céline Ridame, and Cécile Guieu
Biogeosciences, 18, 5699–5717, https://doi.org/10.5194/bg-18-5699-2021, https://doi.org/10.5194/bg-18-5699-2021, 2021
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Simultaneous in situ measurements of (dry and wet) atmospheric deposition and biogeochemical stocks and fluxes in the sunlit waters of the open Mediterranean Sea revealed complex physical and biological processes occurring within the mixed layer. Nitrogen (N) budgets were computed to compare the sources and sinks of N in the mixed layer. The transitory effect observed after a wet dust deposition impacted the microbial food web down to the deep chlorophyll maximum.
Frédéric Gazeau, France Van Wambeke, Emilio Marañón, Maria Pérez-Lorenzo, Samir Alliouane, Christian Stolpe, Thierry Blasco, Nathalie Leblond, Birthe Zäncker, Anja Engel, Barbara Marie, Julie Dinasquet, and Cécile Guieu
Biogeosciences, 18, 5423–5446, https://doi.org/10.5194/bg-18-5423-2021, https://doi.org/10.5194/bg-18-5423-2021, 2021
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Our study shows that the impact of dust deposition on primary production depends on the initial composition and metabolic state of the tested community and is constrained by the amount of nutrients added, to sustain both the fast response of heterotrophic prokaryotes and the delayed one of phytoplankton. Under future environmental conditions, heterotrophic metabolism will be more impacted than primary production, therefore reducing the capacity of surface waters to sequester anthropogenic CO2.
Evelyn Freney, Karine Sellegri, Alessia Nicosia, Leah R. Williams, Matteo Rinaldi, Jonathan T. Trueblood, André S. H. Prévôt, Melilotus Thyssen, Gérald Grégori, Nils Haëntjens, Julie Dinasquet, Ingrid Obernosterer, France Van Wambeke, Anja Engel, Birthe Zäncker, Karine Desboeufs, Eija Asmi, Hilkka Timonen, and Cécile Guieu
Atmos. Chem. Phys., 21, 10625–10641, https://doi.org/10.5194/acp-21-10625-2021, https://doi.org/10.5194/acp-21-10625-2021, 2021
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In this work, we present observations of the organic aerosol content in primary sea spray aerosols (SSAs) continuously generated along a 5-week cruise in the Mediterranean. This information is combined with seawater biogeochemical properties also measured continuously along the ship track to develop a number of parametrizations that can be used in models to determine SSA organic content in oligotrophic waters that represent 60 % of the oceans from commonly measured seawater variables.
Gerd Krahmann, Damian L. Arévalo-Martínez, Andrew W. Dale, Marcus Dengler, Anja Engel, Nicolaas Glock, Patricia Grasse, Johannes Hahn, Helena Hauss, Mark Hopwood, Rainer Kiko, Alexandra Loginova, Carolin R. Löscher, Marie Maßmig, Alexandra-Sophie Roy, Renato Salvatteci, Stefan Sommer, Toste Tanhua, and Hela Mehrtens
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2020-308, https://doi.org/10.5194/essd-2020-308, 2021
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The project "Climate-Biogeochemistry Interactions in the Tropical Ocean" (SFB 754) was a multidisciplinary research project active from 2008 to 2019 aimed at a better understanding of the coupling between the tropical climate and ocean circulation and the ocean's oxygen and nutrient balance. On 34 research cruises, mainly in the Southeast Tropical Pacific and the Northeast Tropical Atlantic, 1071 physical, chemical and biological data sets were collected.
France Van Wambeke, Elvira Pulido, Philippe Catala, Julie Dinasquet, Kahina Djaoudi, Anja Engel, Marc Garel, Sophie Guasco, Barbara Marie, Sandra Nunige, Vincent Taillandier, Birthe Zäncker, and Christian Tamburini
Biogeosciences, 18, 2301–2323, https://doi.org/10.5194/bg-18-2301-2021, https://doi.org/10.5194/bg-18-2301-2021, 2021
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Michaelis–Menten kinetics were determined for alkaline phosphatase, aminopeptidase and β-glucosidase in the Mediterranean Sea. Although the ectoenzymatic-hydrolysis contribution to heterotrophic prokaryotic needs was high in terms of N, it was low in terms of C. This study points out the biases in interpretation of the relative differences in activities among the three tested enzymes in regard to the choice of added concentrations of fluorogenic substrates.
Jonathan V. Trueblood, Alessia Nicosia, Anja Engel, Birthe Zäncker, Matteo Rinaldi, Evelyn Freney, Melilotus Thyssen, Ingrid Obernosterer, Julie Dinasquet, Franco Belosi, Antonio Tovar-Sánchez, Araceli Rodriguez-Romero, Gianni Santachiara, Cécile Guieu, and Karine Sellegri
Atmos. Chem. Phys., 21, 4659–4676, https://doi.org/10.5194/acp-21-4659-2021, https://doi.org/10.5194/acp-21-4659-2021, 2021
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Sea spray aerosols (SSAs) can be an important source of ice-nucleating particles (INPs) that impact cloud properties over the oceans. In the Mediterranean Sea, we found that the INPs in the seawater surface microlayer increased by an order of magnitude after a rain dust event that impacted iron and bacterial abundances. The INP properties of SSA (INPSSA) increased after a 3 d delay. Outside this event, INPSSA could be parameterized as a function of the seawater biogeochemistry.
Birthe Zäncker, Michael Cunliffe, and Anja Engel
Biogeosciences, 18, 2107–2118, https://doi.org/10.5194/bg-18-2107-2021, https://doi.org/10.5194/bg-18-2107-2021, 2021
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Fungi are found in numerous marine environments. Our study found an increased importance of fungi in the Ionian Sea, where bacterial and phytoplankton counts were reduced, but organic matter was still available, suggesting fungi might benefit from the reduced competition from bacteria in low-nutrient, low-chlorophyll (LNLC) regions.
Emilio Marañón, France Van Wambeke, Julia Uitz, Emmanuel S. Boss, Céline Dimier, Julie Dinasquet, Anja Engel, Nils Haëntjens, María Pérez-Lorenzo, Vincent Taillandier, and Birthe Zäncker
Biogeosciences, 18, 1749–1767, https://doi.org/10.5194/bg-18-1749-2021, https://doi.org/10.5194/bg-18-1749-2021, 2021
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The concentration of chlorophyll is commonly used as an indicator of the abundance of photosynthetic plankton (phytoplankton) in lakes and oceans. Our study investigates why a deep chlorophyll maximum, located near the bottom of the upper, illuminated layer develops in the Mediterranean Sea. We find that the acclimation of cells to low light is the main mechanism involved and that this deep maximum represents also a maximum in the biomass and carbon fixation activity of phytoplankton.
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Co-editor-in-chief
The sea surface microlayer (SML) is the thin layer on top of the ocean that is in direct contact with the atmosphere which is crucial for air–sea interactions. A novel paper shows data profiles close to the water surface in a mesocosm experiment. Using microsensor profiles at high vertical resolution, it shows dissolved oxygen and temperature gradients from the air, through the sea surface microlayer and into the water below. Phytoplankton bloom dynamics and surfactant concentrations influence the oxygen concentration and the diffusive layer depth but not temperature gradients. This has implications for air-sea exchanges across the sea surface microlayer.
The sea surface microlayer (SML) is the thin layer on top of the ocean that is in direct contact...
Short summary
Microsensors measuring oxygen and temperature were used to gain high-resolution profiles across the surface of a water basin, in which an algal bloom was induced. These novel data show that the oxygen at the sea surface is highly influenced by algal blooms, while the temperature is only indirectly affected by them. Since algal blooms occur globally, this has considerable implications for calculating global air-sea exchanges of gases or heat, especially under low-wind conditions.
Microsensors measuring oxygen and temperature were used to gain high-resolution profiles across...
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