Articles | Volume 15, issue 10
https://doi.org/10.5194/bg-15-3107-2018
© Author(s) 2018. 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-15-3107-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 May 2018
Research article |
| 22 May 2018
| 22 May 2018
Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the western tropical South Pacific Ocean
Aix Marseille Université, CNRS/INSU,
Université de Toulon, IRD, Mediterranean Institute
of Oceanography (MIO) UM 110, 98848 Nouméa, New
Caledonia
Marine Biology Section, Department of Biology, University
of Copenhagen, 3000 Helsingør, Denmark
Katyanne M. Shoemaker
Department of Biology, University of Massachusetts
Dartmouth, 285 Old Westport Road, North Dartmouth, MA
02747, USA
Pia H. Moisander
Department of Biology, University of Massachusetts
Dartmouth, 285 Old Westport Road, North Dartmouth, MA
02747, USA
Jutta Niggemann
Research Group for Marine Geochemistry (MPI-ICBM Bridging
Group), Institute for Chemistry and Biology of the Marine
Environment University of Oldenburg, Carl-von-Ossietzky-Strasse
9–11, 26129 Oldenburg, Germany
Thorsten Dittmar
Research Group for Marine Geochemistry (MPI-ICBM Bridging
Group), Institute for Chemistry and Biology of the Marine
Environment University of Oldenburg, Carl-von-Ossietzky-Strasse
9–11, 26129 Oldenburg, Germany
Solange Duhamel
Lamont-Doherty Earth Observatory, Division of Biology and
Paleo Environment, Columbia University, P.O. Box 1000, 61
Route 9W, Palisades, NJ 10964, USA
Olivier Grosso
Aix Marseille Université, CNRS/INSU,
Université de Toulon, IRD, Mediterranean Institute
of Oceanography (MIO) UM 110, 13288 Marseille, France
Mireille Pujo-Pay
Laboratoire d'Océanographie Microbienne – UMR 7321, CNRS – Sorbonne Universités, UPMC
Univ Paris 06, Observatoire Océanologique,
66650 Banyuls-sur-mer, France
Sandra Hélias-Nunige
Aix Marseille Université, CNRS/INSU,
Université de Toulon, IRD, Mediterranean Institute
of Oceanography (MIO) UM 110, 13288 Marseille, France
Alain Fumenia
Aix Marseille Université, CNRS/INSU,
Université de Toulon, IRD, Mediterranean Institute
of Oceanography (MIO) UM 110, 98848 Nouméa, New
Caledonia
Sophie Bonnet
Aix Marseille Université, CNRS/INSU,
Université de Toulon, IRD, Mediterranean Institute
of Oceanography (MIO) UM 110, 98848 Nouméa, New
Caledonia
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Mathieu Caffin, Thierry Moutin, Rachel Ann Foster, Pascale Bouruet-Aubertot, Andrea Michelangelo Doglioli, Hugo Berthelot, Cécile Guieu, Olivier Grosso, Sandra Helias-Nunige, Nathalie Leblond, Audrey Gimenez, Anne Alexandra Petrenko, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 15, 2565–2585, https://doi.org/10.5194/bg-15-2565-2018, https://doi.org/10.5194/bg-15-2565-2018, 2018
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We performed N budgets to assess the role of N2 fixation on production and export in the western tropical South Pacific Ocean. We deployed a combination of techniques including high-sensitivity measurements of N input and sediment traps deployment. We demonstrated that N2 fixation was the major source of new N before atmospheric deposition and upward nitrate fluxes. It contributed significantly to organic matter export, indicating a high efficiency of this region to export carbon.
Louise Rousselet, Alain de Verneil, Andrea M. Doglioli, Anne A. Petrenko, Solange Duhamel, Christophe Maes, and Bruno Blanke
Biogeosciences, 15, 2411–2431, https://doi.org/10.5194/bg-15-2411-2018, https://doi.org/10.5194/bg-15-2411-2018, 2018
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Marcus Stenegren, Andrea Caputo, Carlo Berg, Sophie Bonnet, and Rachel A. Foster
Biogeosciences, 15, 1559–1578, https://doi.org/10.5194/bg-15-1559-2018, https://doi.org/10.5194/bg-15-1559-2018, 2018
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Pierre Marrec, Gérald Grégori, Andrea M. Doglioli, Mathilde Dugenne, Alice Della Penna, Nagib Bhairy, Thierry Cariou, Sandra Hélias Nunige, Soumaya Lahbib, Gilles Rougier, Thibaut Wagener, and Melilotus Thyssen
Biogeosciences, 15, 1579–1606, https://doi.org/10.5194/bg-15-1579-2018, https://doi.org/10.5194/bg-15-1579-2018, 2018
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The objective of this study was to better understand the variability of the phytoplankton community structure in small physical structures at the surface of the ocean. After identifying such a structure in the Mediterranean Sea, we deployed cutting-edge physical and biological sensors in order to observe at a high frequency the dynamics of this structure. From these observations we described the variations of the phytoplankton community structure and how the physics controls this variability.
Alain Fumenia, Thierry Moutin, Sophie Bonnet, Mar Benavides, Anne Petrenko, Sandra Helias Nunige, and Christophe Maes
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-557, https://doi.org/10.5194/bg-2017-557, 2018
Revised manuscript not accepted
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The Melanesian archipelago waters between 160° E and 170° W are characterized by a significant N2 fixation rates and an excess of particulate organic nitrogen compared to the canonical ratio of Redfield and a positive N*. We hypothesize that the southern branch of the subtropical gyre is probably the main vector of excess nitrogen transport in the thermocline waters showing an influence of nitrogen fixation occurring in the western tropical in a large part of the South Pacific.
Yangyang Lu, Zuozhu Wen, Dalin Shi, Mingming Chen, Yao Zhang, Sophie Bonnet, Yuhang Li, Jiwei Tian, and Shuh-Ji Kao
Biogeosciences, 15, 1–12, https://doi.org/10.5194/bg-15-1-2018, https://doi.org/10.5194/bg-15-1-2018, 2018
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We investigated the light response of field Trichodesmium N2 fixation and net dissolved nitrogen release behavior. Our results suggest that N2 fixation was a function of light intensity, and the light requirement of Trichodesmium nitrogen fixation was high relative to its photosynthetic light demand. Meanwhile, light is a crucial parameter driving the physiological state of Trichodesmium, which subsequently determined the C / N metabolism and net dissolved nitrogen release.
Thierry Moutin, Andrea Michelangelo Doglioli, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 14, 3207–3220, https://doi.org/10.5194/bg-14-3207-2017, https://doi.org/10.5194/bg-14-3207-2017, 2017
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The overall goal of OUTPACE was to obtain a successful representation of the interactions between planktonic organisms and the cycle of biogenic elements in the western tropical South Pacific Ocean across trophic and N2 fixation gradients. The international OUTPACE cruise took place between 18 February and 3 April 2015 aboard the RV L’Atalante and involved 60 scientists. The transect covered ~4 000 km from the western part of the Melanesian archipelago to the western boundary of the gyre.
Audrey Gimenez, Melika Baklouti, Sophie Bonnet, and Thierry Moutin
Biogeosciences, 13, 5103–5120, https://doi.org/10.5194/bg-13-5103-2016, https://doi.org/10.5194/bg-13-5103-2016, 2016
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In the context of the VAHINE mesocosm experiment in the Nouméa lagoon (New Caledonia), a 1-D vertical biogeochemical mechanistic model was used together with the in situ experiment to complement our comprehension of the planktonic ecosystem dynamics and the main biogeochemical carbon, nitrogen and phosphate fluxes. The model also showed the fate of fixed N2 by providing, over time, the proportion of diazotroph-derived nitrogen (DDN) in each compartment (mineral and organic) of the model.
Angela N. Knapp, Sarah E. Fawcett, Alfredo Martínez-Garcia, Nathalie Leblond, Thierry Moutin, and Sophie Bonnet
Biogeosciences, 13, 4645–4657, https://doi.org/10.5194/bg-13-4645-2016, https://doi.org/10.5194/bg-13-4645-2016, 2016
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The goal of this manuscript was to track the fate of newly fixed nitrogen (N) in large volume mesocosms in the coastal waters of New Caledonia. We used a N isotope ("δ15N") budget and found a shift in the δ15N of sinking particulate N over the 23-day experiment, indicating that nitrate supported export production at the beginning of the experiment, but that nitrogen fixation supported export at the end. We infer that nitrogen fixation supported export production by a release of dissolved N.
Sophie Bonnet, Melika Baklouti, Audrey Gimenez, Hugo Berthelot, and Ilana Berman-Frank
Biogeosciences, 13, 4461–4479, https://doi.org/10.5194/bg-13-4461-2016, https://doi.org/10.5194/bg-13-4461-2016, 2016
Dina Spungin, Ulrike Pfreundt, Hugo Berthelot, Sophie Bonnet, Dina AlRoumi, Frank Natale, Wolfgang R. Hess, Kay D. Bidle, and Ilana Berman-Frank
Biogeosciences, 13, 4187–4203, https://doi.org/10.5194/bg-13-4187-2016, https://doi.org/10.5194/bg-13-4187-2016, 2016
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The marine cyanobacterium Trichodesmium spp. forms massive blooms important to carbon and nitrogen cycling in the oceans that often collapse abruptly. We investigated a Trichodesmium bloom in the lagoon waters of New Caledonia to specifically elucidate the cellular processes mediating the bloom decline. We demonstrate physiological, biochemical, and genetic evidence for nutrient and oxidative stress that induced a genetically controlled programmed cell death (PCD) pathway leading to bloom demise.
Ulrike Pfreundt, Dina Spungin, Sophie Bonnet, Ilana Berman-Frank, and Wolfgang R. Hess
Biogeosciences, 13, 4135–4149, https://doi.org/10.5194/bg-13-4135-2016, https://doi.org/10.5194/bg-13-4135-2016, 2016
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The VAHINE experiment in the New Caledonia lagoon (SW Pacific) targeted the dynamics of nutrient pools and fluxes, N2 fixation, and the composition and productivity of the microbial communities. To connect this information to the actual activities of diverse microbial taxa, we present the analysis of the community-wide gene expression for 23 days. The results from this experiment provide insight into the microbial activities in a low-nutrient, low-chlorophyll ecosystem and within a mesocosm.
Hugo Berthelot, Sophie Bonnet, Olivier Grosso, Véronique Cornet, and Aude Barani
Biogeosciences, 13, 4005–4021, https://doi.org/10.5194/bg-13-4005-2016, https://doi.org/10.5194/bg-13-4005-2016, 2016
France Van Wambeke, Ulrike Pfreundt, Aude Barani, Hugo Berthelot, Thierry Moutin, Martine Rodier, Wolfgang R. Hess, and Sophie Bonnet
Biogeosciences, 13, 3187–3202, https://doi.org/10.5194/bg-13-3187-2016, https://doi.org/10.5194/bg-13-3187-2016, 2016
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The phytoplankton is at the base of the plankton food web in large parts of oceanic "deserts" such as the South Pacific Ocean, where nitrogen sources limit activity. Mesocosms were fertilized with phosphorus to stimulate diazotrophy (atmospheric N2 fixation). Mostly diazotroph-derived nitrogen fuelled the heterotrophic bacterial community through indirect processes generating dissolved organic matter and detritus, such as mortality, lysis and grazing of both diazotrophs and non-diazotrophs.
Brian P. V. Hunt, Sophie Bonnet, Hugo Berthelot, Brandon J. Conroy, Rachel A. Foster, and Marc Pagano
Biogeosciences, 13, 3131–3145, https://doi.org/10.5194/bg-13-3131-2016, https://doi.org/10.5194/bg-13-3131-2016, 2016
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Biological nitrogen (N) fixation is an important source of N for food webs in tropical and subtropical oceans. However, uptake pathways remain poorly understood. This study found that fixed N contributed a third of total zooplankton N in the New Caledonia lagoon. Fixed N reached the zooplankton through 1) direct grazing on N fixers and 2) grazing on phytoplankton that had taken up N released by fixers. We report the first record of direct zooplankton grazing on the unicellular N fixer UCYN-C.
Sophie Bonnet, Thierry Moutin, Martine Rodier, Jean-Michel Grisoni, Francis Louis, Eric Folcher, Bertrand Bourgeois, Jean-Michel Boré, and Armelle Renaud
Biogeosciences, 13, 2803–2814, https://doi.org/10.5194/bg-13-2803-2016, https://doi.org/10.5194/bg-13-2803-2016, 2016
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e main goal of the VAHINE project was to study the fate of N2 fixation in the ocean. Three large-volume (~ 50 m3) mesocosms were deployed in a tropical oligotrophic ecosystem (the New Caledonia lagoon, south-eastern Pacific). This introductory paper describes the scientific objectives of the project in detail as well as the implementation plan: the mesocosm description and deployment, the selection of the study site, and the logistical and sampling strategy.
Sophie Bonnet, Hugo Berthelot, Kendra Turk-Kubo, Sarah Fawcett, Eyal Rahav, Stéphane L'Helguen, and Ilana Berman-Frank
Biogeosciences, 13, 2653–2673, https://doi.org/10.5194/bg-13-2653-2016, https://doi.org/10.5194/bg-13-2653-2016, 2016
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N2 fixation rates were measured daily in ~ 50 m3 mesocosms deployed in New Caledonia to investigate the high-frequency dynamics of diazotrophy and the fate of diazotroph-derived nitrogen (DDN) oligotrophic ecosystems. ~ 10 % of UCYN-C from the water column were exported daily to the traps, representing as much as 22.4 ± 5.5 % of the total POC exported at the height of the UCYN-C bloom. 16 ± 6 % of the DDN was released to the dissolved pool and 21 ± 4 % was transferred to non-diazotrophic plankton.
Ulrike Pfreundt, France Van Wambeke, Mathieu Caffin, Sophie Bonnet, and Wolfgang R. Hess
Biogeosciences, 13, 2319–2337, https://doi.org/10.5194/bg-13-2319-2016, https://doi.org/10.5194/bg-13-2319-2016, 2016
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The Southwest Pacific has one of the highest N2 fixation rates in the global ocean, yet information is scarce on the bacterioplankton interrelationships. We detected high microbial diversity in the New Caledonia lagoon and inside a 50 000 L experimental enclosure of the same water mass over 3 weeks and give evidence for previously unknown niche partitioning. Phosphate fertilization promoted the growth of efficient N2 fixing cyanobacteria triggering the growth of most heterotrophic bacteria.
K. A. Turk-Kubo, I. E. Frank, M. E. Hogan, A. Desnues, S. Bonnet, and J. P. Zehr
Biogeosciences, 12, 7435–7452, https://doi.org/10.5194/bg-12-7435-2015, https://doi.org/10.5194/bg-12-7435-2015, 2015
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-A shift from diatom-associated diazotrophs (DDAs) to unicellular cyanobacterial group C (UCYN-C) in response to DIP fertilization was captured in a large-scale mesocosm experiment in the Noumea lagoon (NL), a low-nutrient low-chlorophyll coastal environment. -First report of in situ net growth and mortality rates for unicellular diazotrophs UCYN-A2, and UCYN-C. -First quantitative abundance data for diazotrophs in NL indicate that DDAs and UCYN-A1/A2 may be important N2 fixers in this region.
H. Berthelot, T. Moutin, S. L'Helguen, K. Leblanc, S. Hélias, O. Grosso, N. Leblond, B. Charrière, and S. Bonnet
Biogeosciences, 12, 4099–4112, https://doi.org/10.5194/bg-12-4099-2015, https://doi.org/10.5194/bg-12-4099-2015, 2015
C. Ridame, J. Dekaezemacker, C. Guieu, S. Bonnet, S. L'Helguen, and F. Malien
Biogeosciences, 11, 4783–4800, https://doi.org/10.5194/bg-11-4783-2014, https://doi.org/10.5194/bg-11-4783-2014, 2014
Related subject area
Biodiversity and Ecosystem Function: Marine
Multifactorial effects of warming, low irradiance, and low salinity on Arctic kelps
Early life stages of fish under ocean alkalinity enhancement in coastal plankton communities
Planktonic foraminifera assemblage composition and flux dynamics inferred from an annual sediment trap record in the central Mediterranean Sea
Reefal ostracod assemblages from the Zanzibar Archipelago (Tanzania)
Composite calcite and opal test in Foraminifera (Rhizaria)
Influence of oxygen minimum zone on macrobenthic community structure in the northern Benguela Upwelling System: a macro-nematode perspective
Phytoplankton adaptation to steady or changing environments affects marine ecosystem functioning
Simulated terrestrial runoff shifts the metabolic balance of a coastal Mediterranean plankton community towards heterotrophy
Contrasting carbon cycling in the benthic food webs between a river-fed, high-energy canyon and an upper continental slope
A critical trade-off between nitrogen quota and growth allows Coccolithus braarudii life cycle phases to exploit varying environment
Structural complexity and benthic metabolism: resolving the links between carbon cycling and biodiversity in restored seagrass meadows
Building your own mountain: the effects, limits, and drawbacks of cold-water coral ecosystem engineering
Phytoplankton response to increased nickel in the context of ocean alkalinity enhancement
Year-long benthic measurements of environmental conditions indicate high sponge biomass is related to strong bottom currents over the Northern Labrador shelf
Diversity and density relationships between lebensspuren and tracemaking organisms: a study case from abyssal northwest Pacific
Technical note: An autonomous flow-through salinity and temperature perturbation mesocosm system for multi-stressor experiments
Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves
A step towards measuring connectivity in the deep sea: elemental fingerprints of mollusk larval shells discriminate hydrothermal vent sites
Seasonal foraging behavior of Weddell seals relation to oceanographic environmental conditions in the Ross Sea, Antarctica
Spawner weight and ocean temperature drive Allee effect dynamics in Atlantic cod, Gadus morhua: inherent and emergent density regulation
Bacterioplankton dark CO2 fixation in oligotrophic waters
The bottom mixed layer depth as an indicator of subsurface Chlorophyll a distribution
Ideas and perspectives: The fluctuating nature of oxygen shapes the ecology of aquatic habitats and their biogeochemical cycles – the aquatic oxyscape
Impact of deoxygenation and warming on global marine species in the 21st century
Ecological divergence of a mesocosm in an eastern boundary upwelling system assessed with multi-marker environmental DNA metabarcoding
Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia
Upwelled plankton community modulates surface bloom succession and nutrient availability in a natural plankton assemblage
First phytoplankton community assessment of the Kong Håkon VII Hav, Southern Ocean, during austral autumn
Early life stages of a Mediterranean coral are vulnerable to ocean warming and acidification
Mediterranean seagrasses as carbon sinks: methodological and regional differences
Contrasting vertical distributions of recent planktic foraminifera off Indonesia during the southeast monsoon: implications for paleoceanographic reconstructions
The onset of the spring phytoplankton bloom in the coastal North Sea supports the Disturbance Recovery Hypothesis
Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas
Modeling the growth and sporulation dynamics of the macroalga Ulva in mixed-age populations in cultivation and the formation of green tides
Spatial changes in community composition and food web structure of mesozooplankton across the Adriatic basin (Mediterranean Sea)
Predicting mangrove forest dynamics across a soil salinity gradient using an individual-based vegetation model linked with plant hydraulics
Will daytime community calcification reflect reef accretion on future, degraded coral reefs?
Modeling polar marine ecosystem functions guided by bacterial physiological and taxonomic traits
Quantifying functional consequences of habitat degradation on a Caribbean coral reef
Enhanced chlorophyll-a concentration in the wake of Sable Island, eastern Canada, revealed by two decades of satellite observations: a response to grey seal population dynamics?
Population dynamics and reproduction strategies of planktonic foraminifera in the open ocean
The Bouraké semi-enclosed lagoon (New Caledonia) – a natural laboratory to study the lifelong adaptation of a coral reef ecosystem to extreme environmental conditions
Atypical, high-diversity assemblages of foraminifera in a mangrove estuary in northern Brazil
Permanent ectoplasmic structures in deep-sea Cibicides and Cibicidoides taxa – long-term observations at in situ pressure
Ideas and perspectives: Ushering the Indian Ocean into the UN Decade of Ocean Science for Sustainable Development (UNDOSSD) through marine ecosystem research and operational services – an early career's take
Persistent effects of sand extraction on habitats and associated benthic communities in the German Bight
Spatial patterns of ectoenzymatic kinetics in relation to biogeochemical properties in the Mediterranean Sea and the concentration of the fluorogenic substrate used
A 2-decade (1988–2009) record of diatom fluxes in the Mauritanian coastal upwelling: impact of low-frequency forcing and a two-step shift in the species composition
Review and syntheses: Impacts of turbidity flows on deep-sea benthic communities
Ideas and perspectives: When ocean acidification experiments are not the same, repeatability is not tested
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.
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.
Isabell Hochfeld and Jana Hinners
EGUsphere, https://doi.org/10.5194/egusphere-2024-1246, https://doi.org/10.5194/egusphere-2024-1246, 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.
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.
Evert de Froe, Igor Yashayaev, Christian Mohn, Johanne Vad, Furu Mienis, Gerard Duineveld, Ellen Kenchington, Erica Head, Steve Ross, Sabena Blackbird, George Wolff, Murray Roberts, Barry MacDonald, Graham Tulloch, and Dick van Oevelen
EGUsphere, https://doi.org/10.31223/X58968, https://doi.org/10.31223/X58968, 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 favor 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 favorable regional ocean currents.
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.
Hyunjae Chung, Jikang Park, Mijin Park, Yejin Kim, Unyoung Chun, Sukyoung Yun, Won Sang Lee, Seung-Tae Yoon, and Won Young Lee
EGUsphere, https://doi.org/10.5194/egusphere-2023-2757, https://doi.org/10.5194/egusphere-2023-2757, 2024
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Understanding how marine animals adapt to spatial and temporal shifts in oceanographic conditions is of utmost importance. In this paper, we investigated the influence of changes in seawater properties on the seasonal 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.
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.
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.
Federica Maggioni, Mireille Pujo-Pay, Jérome Aucan, Carlo Cerrano, Barbara Calcinai, Claude Payri, Francesca Benzoni, Yves Letourneur, and Riccardo Rodolfo-Metalpa
Biogeosciences, 18, 5117–5140, https://doi.org/10.5194/bg-18-5117-2021, https://doi.org/10.5194/bg-18-5117-2021, 2021
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Based on current experimental evidence, climate change will affect up to 90 % of coral reefs worldwide. The originality of this study arises from our recent discovery of an exceptional study site where environmental conditions (temperature, pH, and oxygen) are even worse than those forecasted for the future.
While these conditions are generally recognized as unfavorable for marine life, we found a rich and abundant coral reef thriving under such extreme environmental conditions.
Nisan Sariaslan and Martin R. Langer
Biogeosciences, 18, 4073–4090, https://doi.org/10.5194/bg-18-4073-2021, https://doi.org/10.5194/bg-18-4073-2021, 2021
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Analyses of foraminiferal assemblages from the Mamanguape mangrove estuary (northern Brazil) revealed highly diverse, species-rich, and structurally complex biotas. The atypical fauna resembles shallow-water offshore assemblages and are interpreted to be the result of highly saline ocean waters penetrating deep into the estuary. The findings contrast with previous studies, have implications for the fossil record, and provide novel perspectives for reconstructing mangrove environments.
Jutta E. Wollenburg, Jelle Bijma, Charlotte Cremer, Ulf Bickmeyer, and Zora Mila Colomba Zittier
Biogeosciences, 18, 3903–3915, https://doi.org/10.5194/bg-18-3903-2021, https://doi.org/10.5194/bg-18-3903-2021, 2021
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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.
Kumar Nimit
Biogeosciences, 18, 3631–3635, https://doi.org/10.5194/bg-18-3631-2021, https://doi.org/10.5194/bg-18-3631-2021, 2021
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The Indian Ocean Rim hosts many of the underdeveloped and emerging economies that depend on ocean resources for the livelihood of millions. Operational ocean information services cater to the requirements of resource managers and end-users to efficiently harness resources, mitigate threats and ensure safety. This paper outlines existing tools and explores the ongoing research that has the potential to convert the findings into operational services in the near- to midterm.
Finn Mielck, Rune Michaelis, H. Christian Hass, Sarah Hertel, Caroline Ganal, and Werner Armonies
Biogeosciences, 18, 3565–3577, https://doi.org/10.5194/bg-18-3565-2021, https://doi.org/10.5194/bg-18-3565-2021, 2021
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Marine sand mining is becoming more and more important to nourish fragile coastlines that face global change. We investigated the largest sand extraction site in the German Bight. The study reveals that after more than 35 years of mining, the excavation pits are still detectable on the seafloor while the sediment composition has largely changed. The organic communities living in and on the seafloor were strongly decimated, and no recovery is observable towards previous conditions.
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.
Oscar E. Romero, Simon Ramondenc, and Gerhard Fischer
Biogeosciences, 18, 1873–1891, https://doi.org/10.5194/bg-18-1873-2021, https://doi.org/10.5194/bg-18-1873-2021, 2021
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Upwelling intensity along NW Africa varies on the interannual to decadal timescale. Understanding its changes is key for the prediction of future changes of CO2 sequestration in the northeastern Atlantic. Based on a multiyear (1988–2009) sediment trap experiment at the site CBmeso, fluxes and the species composition of the diatom assemblage are presented. Our data help in establishing the scientific basis for forecasting and modeling future states of this ecosystem and its decadal changes.
Katharine T. Bigham, Ashley A. Rowden, Daniel Leduc, and David A. Bowden
Biogeosciences, 18, 1893–1908, https://doi.org/10.5194/bg-18-1893-2021, https://doi.org/10.5194/bg-18-1893-2021, 2021
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Turbidity flows – underwater avalanches – are large-scale physical disturbances believed to have profound impacts on productivity and diversity of benthic communities in the deep sea. We reviewed published studies and found that current evidence for changes in productivity is ambiguous at best, but the influence on regional and local diversity is clearer. We suggest study design criteria that may lead to a better understanding of large-scale disturbance effects on deep-sea benthos.
Phillip Williamson, Hans-Otto Pörtner, Steve Widdicombe, and Jean-Pierre Gattuso
Biogeosciences, 18, 1787–1792, https://doi.org/10.5194/bg-18-1787-2021, https://doi.org/10.5194/bg-18-1787-2021, 2021
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The reliability of ocean acidification research was challenged in early 2020 when a high-profile paper failed to corroborate previously observed impacts of high CO2 on the behaviour of coral reef fish. We now know the reason why: the
replicatedstudies differed in many ways. Open-minded and collaborative assessment of all research results, both negative and positive, remains the best way to develop process-based understanding of the impacts of ocean acidification on marine organisms.
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Short summary
We measured N2 fixation rates and identified diazotrophic phylotypes in the mesopelagic layer along a transect spanning from New Caledonia to French Polynesia. N2 fixation rates were low but consistently detected across all depths and stations. A distinct diazotrophic phylotype dominated at 650 dbar, coinciding with the oxygenated Subantarctic Mode Water (SAMW) and suggesting that the distribution of aphotic diazotroph communities is to some extent controlled by water mass structure.
We measured N2 fixation rates and identified diazotrophic phylotypes in the mesopelagic layer...
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