186 results on '"Alessandro Tagliabue"'
Search Results
2. Knowledge Gaps in Quantifying the Climate Change Response of Biological Storage of Carbon in the Ocean
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Stephanie Henson, Chelsey A. Baker, Paul Halloran, Abigail McQuatters‐Gollop, Stuart Painter, Alban Planchat, and Alessandro Tagliabue
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biological carbon pump ,alkalinity ,primary production ,interior respiration ,gap analysis ,survey ,Environmental sciences ,GE1-350 ,Ecology ,QH540-549.5 - Abstract
Abstract The ocean is responsible for taking up approximately 25% of anthropogenic CO2 emissions and stores >50 times more carbon than the atmosphere. Biological processes in the ocean play a key role, maintaining atmospheric CO2 levels approximately 200 ppm lower than they would otherwise be. The ocean's ability to take up and store CO2 is sensitive to climate change, however the key biological processes that contribute to ocean carbon storage are uncertain, as are how those processes will respond to, and feedback on, climate change. As a result, biogeochemical models vary widely in their representation of relevant processes, driving large uncertainties in the projections of future ocean carbon storage. This review identifies key biological processes that affect how ocean carbon storage may change in the future in three thematic areas: biological contributions to alkalinity, net primary production, and interior respiration. We undertook a review of the existing literature to identify processes with high importance in influencing the future biologically‐mediated storage of carbon in the ocean, and prioritized processes on the basis of both an expert assessment and a community survey. Highly ranked processes in both the expert assessment and survey were: for alkalinity—high level understanding of calcium carbonate production; for primary production—resource limitation of growth, zooplankton processes and phytoplankton loss processes; for respiration—microbial solubilization, particle characteristics and particle type. The analysis presented here is designed to support future field or laboratory experiments targeting new process understanding, and modeling efforts aimed at undertaking biogeochemical model development.
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- 2024
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3. Response of Southern Ocean Resource Stress in a Changing Climate
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Prima Anugerahanti and Alessandro Tagliabue
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Southern Ocean ,co‐limitation ,modeling ,phytoplankton ,biogeochemisty ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Abstract Phytoplankton underpin ocean net primary production (NPP) and Southern Ocean phytoplankton display different ecological‐biogeochemical traits, compared to temperate species. Climate models currently forecast consistent across‐model NPP increases due to climate change, yet neglect specific aspects of the Southern Ocean ecological‐biogeochemical system. We conducted experiments to evaluate how key regional traits, including multiple limiting nutrients, unique photophysiology and differential resource acquisition, drive changes in the projected response of resource stress, NPP and export production under a high emissions scenario. Although Southern Ocean iron limitation is widespread, it declines in the future and is replaced by growing manganese limitation, as concentrations cannot support increasing growth rates. Distinct phytoplankton traits either amplify or dampen climate‐driven changes, depending on whether they are those typical of Antarctic or temperate phytoplankton, respectively. Overall, future Southern Ocean NPP trends may be more uncertain than currently assumed and future efforts should focus on accounting for regional ecological‐biogeochemical differences.
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- 2024
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4. Model exploration of microplastic effects on zooplankton grazing reveal potential impacts on the global carbon cycle
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Camille Richon, Thomas Gorgues, Matthew Cole, Ika Paul-Pont, Christophe Maes, Alessandro Tagliabue, and Charlotte Laufkötter
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microplastics ,zooplankton ,modeling ,carbon cycle ,ocean ,grazing ,Environmental technology. Sanitary engineering ,TD1-1066 ,Environmental sciences ,GE1-350 ,Science ,Physics ,QC1-999 - Abstract
Amongst the increasing number of anthropogenic stress factors threatening ocean equilibrium, microplastics (MP; $ \lt $ 5 mm) have emerged as particularly worrisome. In situ observations have shown that MP accumulate in large areas at the surface ocean where it may threaten the functioning marine species. In particular, experimental evidence has shown that the grazing rates of several zooplankton species may be significantly altered by MP. These direct impacts on zooplankton may alter nutrient and carbon cycling. However, how these laboratory results may translate into impacts on the global ocean is yet unknown. Here, we use a global coupled physical-biogeochemical model including MP (NEMO/PISCES-PLASTIC) to investigate the impacts of MP exposure on zooplankton grazing rates. Drawing from experimental results, we use varying water contamination impact thresholds to explore the biogeochemical consequences of MP impacts on short (10 years) and long timescales (100 years). Our simulations show that the geographical extent of MP impacts on zooplankton remains restricted to about 10% of the global ocean surface, even after 100 years of constant MP contamination. However, in the most contaminated regions (e.g. the sub-tropical gyres), [MP] has surged from a few mg m ^−3 to $ \gt $ 50 mg m ^−3 . Despite their oligotrophic nature and limited contribution to the overall ocean carbon cycle, MP impacts on zooplankton grazing could disrupt carbon cycling in these highly contaminated regions (up to 50% reduction in yearly primary production, carbon export fluxes and organic matter remineralisation after 100 years). Our research suggests that persistent MP pollution in the ocean could diminish primary production by 4%. In spite of the large sensitivity of our results to the water contamination impact threshold, we suggest MP impacts on zooplankton grazing may cause an annual loss of 1 Gt yr ^−1 of exported carbon after 100 years, if MP inputs remain constant globally.
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- 2024
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5. Impact of intensifying nitrogen limitation on ocean net primary production is fingerprinted by nitrogen isotopes
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Pearse J. Buchanan, Olivier Aumont, Laurent Bopp, Claire Mahaffey, and Alessandro Tagliabue
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Science - Abstract
Projected declines in marine primary production are underpinned by a slowdown in nitrogen supplied to surface waters. Here the authors detail a new means to detect this slowdown and describe major shifts in the 21st century oceanic nitrogen cycle.
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- 2021
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6. Emergent interactive effects of climate change and contaminants in coastal and ocean ecosystems
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Vanessa Hatje, Manmohan Sarin, Sylvia G. Sander, Dario Omanović, Purvaja Ramachandran, Christoph Völker, Ricardo O. Barra, and Alessandro Tagliabue
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pollutants ,impacts ,knowledge gaps ,ecosystem impacts ,health impacts ,climate change ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The effects of climate change (CC) on contaminants and their potential consequences to marine ecosystem services and human wellbeing are of paramount importance, as they pose overlapping risks. Here, we discuss how the interaction between CC and contaminants leads to poorly constrained impacts that affects the sensitivity of organisms to contamination leading to impaired ecosystem function, services and risk assessment evaluations. Climate drivers, such as ocean warming, ocean deoxygenation, changes in circulation, ocean acidification, and extreme events interact with trace metals, organic pollutants, excess nutrients, and radionuclides in a complex manner. Overall, the holistic consideration of the pollutants-climate change nexus has significant knowledge gaps, but will be important in understanding the fate, transport, speciation, bioavailability, toxicity, and inventories of contaminants. Greater focus on these uncertainties would facilitate improved predictions of future changes in the global biogeochemical cycling of contaminants and both human health and marine ecosystems.
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- 2022
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7. Data-Driven Modeling of Dissolved Iron in the Global Ocean
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Yibin Huang, Alessandro Tagliabue, and Nicolas Cassar
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dissolved iron ,monthly climatology ,data-driven model ,machining learning ,controlling mechanism ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The importance of dissolved Fe (dFe) in regulating ocean primary production and the carbon cycle is well established. However, the large-scale distribution and temporal dynamics of dFe remain poorly constrained in part due to incomplete observational coverage. In this study, we use a compilation of published dFe observations (n=32,344) with paired environmental predictors from contemporaneous satellite observations and reanalysis products to build a data-driven surface-to-seafloor dFe climatology with 1°×1° resolution using three machine-learning approaches (random forest, supper vector machine and artificial neural network). Among the three approaches, random forest achieves the highest accuracy with overall R2 and root mean standard error of 0.8 and 0.3 nmol L-1, respectively. Using this data-driven climatology, we explore the possible mechanisms governing the dFe distribution at various depth horizons using statistical metrics such as Pearson correlation coefficients and the rank of predictors importance in the model construction. Our results are consistent with the critical role of aeolian iron supply in enriching surface dFe in the low latitude regions and suggest a far-reaching impact of this source at depth. Away from the surface layer, the strong correlation between dFe and apparent oxygen utilization implies that a combination of regeneration, scavenging and large-scale ocean circulation are controlling the interior distribution of dFe, with hydrothermal inputs important in some regions. Finally, our data-driven dFe climatology can be used as an alternative reference to evaluate the performance of ocean biogeochemical models. Overall, the new global scale climatology of dFe achieved in our study is an important step toward improved representation of dFe in the contemporary ocean and may also be used to guide future sampling strategies.
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- 2022
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8. Taxonomic and nutrient controls on phytoplankton iron quotas in the ocean
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Benjamin S. Twining, Olga Antipova, P. Dreux Chappell, Natalie R. Cohen, Jeremy E. Jacquot, Elizabeth L. Mann, Adrian Marchetti, Daniel C. Ohnemus, Sara Rauschenberg, and Alessandro Tagliabue
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Oceanography ,GC1-1581 - Abstract
Abstract Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of the low‐iron Pacific Ocean. Among diatoms, both pennate and centric genera accumulated luxury iron, but the cosmopolitan pennate genus Pseudo‐nitzschia maintained iron quotas 10‐fold higher than co‐occurring centric diatoms, likely due to enhanced iron storage. Biogeochemical models should account for taxonomic and macronutrient controls on phytoplankton iron quotas.
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- 2021
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9. Arctic seals as tracers of environmental and ecological change
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Camille de la Vega, Claire Mahaffey, Robyn E. Tuerena, David J. Yurkowski, Steven H. Ferguson, Garry B. Stenson, Erling S. Nordøy, Tore Haug, Martin Biuw, Sophie Smout, Jo Hopkins, Alessandro Tagliabue, and Rachel M. Jeffreys
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Oceanography ,GC1-1581 - Abstract
Abstract Knowledge of species trophic position (TP) is an essential component of ecosystem management. Determining TP from stable nitrogen isotopes (δ15N) in predators requires understanding how these tracers vary across environments and how they relate to predator isotope composition. We used two seal species as a model for determining TP across large spatial scales in the Arctic. δ15N in seawater nitrate (δ15NNO3) and seal muscle amino acids (δ15NAA) were determined to independently characterize the base of the food web and the TP of harp and ringed seals, demonstrating a direct link between δ15NNO3 and δ15NAA. Our results show that the spatial variation in δ15NAA in seals reflects the δ15NNO3 end members in Pacific vs. Atlantic waters. This study provides a reference for best practice on accurate comparison of TP in predators and as such, provides a framework to assess the impact of environmental and human‐induced changes on ecosystems at pan‐Arctic scales.
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- 2021
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10. Constraining the Contribution of Hydrothermal Iron to Southern Ocean Export Production Using Deep Ocean Iron Observations
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Alessandro Tagliabue, Andrew R. Bowie, Thomas Holmes, Pauline Latour, Pier van der Merwe, Melanie Gault-Ringold, Kathrin Wuttig, and Joseph A. Resing
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trace metals ,hydrothermalism ,Southern Ocean ,biogeochemical modelling ,iron cycle in oceans ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Hydrothermal iron supply contributes to the Southern Ocean carbon cycle via the regulation of regional export production. However, as hydrothermal iron input estimates are coupled to helium, which are uncertain depending on whether helium inputs are based on ridge spreading rates or inverse modelling, questions remain regarding the magnitude of the export production impacts. A particular challenge is the limited observations of dissolved iron (dFe) supply from the abyssal Southern Ocean ridge system to directly assess different hydrothermal iron supply scenarios. We combine ocean biogeochemical modelling with new observations of dFe from the abyssal Southern Ocean to assess the impact of hydrothermal iron supply estimated from either ridge spreading rate or inverse helium modelling on Southern Ocean export production. The hydrothermal contribution to dFe in the upper 250 m reduces 4–5 fold when supply is based on inverse modelling, relative to those based on spreading rate, translating into a 36–73% reduction in the impact of hydrothermal iron on export production. However, only the spreading rate input scheme reproduces observed dFe anomalies >1 nM around the circum-Antarctic ridge. The model correlation with observations drops 3 fold under the inverse modelling input scheme. The best dFe scenario has a residence time for hydrothermal iron that is between 21 and 34 years, highlighting the importance of rapid physical mixing to surface waters. Overall, because of its short residence time, hydrothermal Fe supplied locally by circum-Antarctic ridges is most important to the Southern Ocean carbon cycle and our results highlight decoupling between hydrothermal iron and helium supply.
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- 2022
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11. Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services
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Alessandro Tagliabue, Lester Kwiatkowski, Laurent Bopp, Momme Butenschön, William Cheung, Matthieu Lengaigne, and Jerome Vialard
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climate change ,ocean net primary production ,earth system model (ESM) ,climate projections ,ocean modeling ,oceanography ,Environmental sciences ,GE1-350 - Abstract
Ocean net primary production (NPP) results from CO2 fixation by marine phytoplankton, catalysing the transfer of organic matter and energy to marine ecosystems, supporting most marine food webs, and fisheries production as well as stimulating ocean carbon sequestration. Thus, alterations to ocean NPP in response to climate change, as quantified by Earth system model experiments conducted as part of the 5th and 6th Coupled Model Intercomparison Project (CMIP5 and CMIP6) efforts, are expected to alter key ecosystem services. Despite reductions in inter-model variability since CMIP5, the ocean components of CMIP6 models disagree roughly 2-fold in the magnitude and spatial distribution of NPP in the contemporary era, due to incomplete understanding and insufficient observational constraints. Projections of NPP change in absolute terms show large uncertainty in CMIP6, most notably in the North Atlantic and the Indo-Pacific regions, with the latter explaining over two-thirds of the total inter-model uncertainty. While the Indo-Pacific has previously been identified as a hotspot for climate impacts on biodiversity and fisheries, the increased inter-model variability of NPP projections further exacerbates the uncertainties of climate risks on ocean-dependent human communities. Drivers of uncertainty in NPP changes at regional scales integrate different physical and biogeochemical factors that require more targeted mechanistic assessment in future studies. Globally, inter-model uncertainty in the projected changes in NPP has increased since CMIP5, which amplifies the challenges associated with the management of associated ecosystem services. Notably, this increased regional uncertainty in the projected NPP change in CMIP6 has occurred despite reduced uncertainty in the regional rates of NPP for historical period. Improved constraints on the magnitude of ocean NPP and the mechanistic drivers of its spatial variability would improve confidence in future changes. It is unlikely that the CMIP6 model ensemble samples the complete uncertainty in NPP, with the inclusion of additional mechanistic realism likely to widen projections further in the future, especially at regional scales. This has important consequences for assessing ecosystem impacts. Ultimately, we need an integrated mechanistic framework that considers how NPP and marine ecosystems respond to impacts of not only climate change, but also the additional non-climate drivers.
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- 2021
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12. The interplay between regeneration and scavenging fluxes drives ocean iron cycling
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Alessandro Tagliabue, Andrew R. Bowie, Timothy DeVries, Michael J. Ellwood, William M. Landing, Angela Milne, Daniel C. Ohnemus, Benjamin S. Twining, and Philip W. Boyd
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Science - Abstract
Iron is crucial for marine photosynthesis, but observational constraints on the magnitude of key iron cycle processes are lacking. Here the authors use a range of observational data sets to demonstrate that the balance between iron re-supply and removal in the subsurface controls upper ocean iron limitation.
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- 2019
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13. Hydrothermal vents trigger massive phytoplankton blooms in the Southern Ocean
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Mathieu Ardyna, Léo Lacour, Sara Sergi, Francesco d’Ovidio, Jean-Baptiste Sallée, Mathieu Rembauville, Stéphane Blain, Alessandro Tagliabue, Reiner Schlitzer, Catherine Jeandel, Kevin Robert Arrigo, and Hervé Claustre
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Science - Abstract
Hydrothermal activity is recognized to be significant in regulating the dynamics of trace elements in the ocean. Here the authors report the first observational evidence of upwelled hydrothermally influenced deep waters stimulating massive phytoplankton blooms in the Southern Ocean.
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- 2019
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14. Quantifying the Impact of Climate Change on Marine Diazotrophy: Insights From Earth System Models
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Lewis Wrightson and Alessandro Tagliabue
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diazotrophy ,climate change ,biogeochemistry ,earth system models ,nitrogen cycle ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Nitrogen fixation is a major source of new nitrogen to the ocean, supporting biological productivity in the large nitrogen-limited tropical oceans. In Earth System Models, the response of nitrogen fixation to climate change acts in concert with projected changes to physical nitrogen supply to regulate the response of primary productivity in nitrogen-limited regions. We examine the response of diazotrophy from nine Earth System Models and find large variability in the magnitude and spatial pattern of nitrogen fixation in both contemporary periods and future projections. Although Earth System Models tend to agree that nitrogen fixation will decrease over the next century, strong regional variations exist, especially in the tropical Pacific which may counteract the response of the Atlantic and Indian oceans. As the climate driven trend of nitrogen fixation emerges by mid-century in the RCP8.5 scenario, on regional scales it may modulate the broad climate trends in productivity that emerge later in the century. The generally poor skill and lack of agreement amongst Earth System Models indicates that the climate response of nitrogen fixation is a key uncertainty in projections of future ocean primary production in the tropical oceans. Overall, we find that the future evolution of nitrogen fixation plays an important role in shaping future trends in net primary production in the tropics, but the poor skill of models highlights significant uncertainty, especially considering the role of multiple concurrent drivers.
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- 2020
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15. Prey Stoichiometry Drives Iron Recycling by Zooplankton in the Global Ocean
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Camille Richon, Olivier Aumont, and Alessandro Tagliabue
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zooplankton ,stoichiometry ,recycling ,predator ,prey ,iron ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Zooplankton occupy a key place in the ocean ecosystems as they constitute a link between primary producers and upper trophic levels, with many commercially important fisheries relying on the presence of zooplankton to sustain fish stocks. Moreover, zooplankton have an important role in supporting primary production as they can recycle large amounts of micronutrients such as iron, facilitating its retention in the surface ocean and alleviating iron limitation of phytoplankton. Intuitively, one may consider that a large quantity of prey should ensure a healthy zooplankton ecosystem, but the microbial oceanic food web is characterized by a great variability in both the composition and quality of preys. This variability may lead to mismatches between predator and prey stoichiometry, which can in turn affect the growth efficiency of zooplankton. Here we show that variations in food quality are the main drivers of changes in iron assimilation and recycling by zooplankton. Making use of a state-of-the-art biogeochemical model that explicitly accounts for the impact of multiple drivers on the iron assimilation efficiency, we quantify the relative drivers of iron recycling in different ocean regions and across seasons. Our results can be reconciled within a conceptual framework that links the assimilation efficiency of zooplankton to predator-prey stoichiometric mismatch and zooplankton physiological assumptions. If predator and prey stoichiometries are close, then the micronutrient assimilation by zooplankton is optimal and recycling is low. Any departure from this optimal stoichiometry leads to a decrease in assimilation efficiency and a subsequent increase in micronutrient recycling. This framework can be used to understand the impact of variability in prey food quality on iron recycling from previous experiments and generates clear hypotheses about the relative importance of recycling for other micronutrients such as copper, cobalt, manganese, and zinc. Finally, our findings highlight the importance of future changes in prey food quality in driving recycling rates of micronutrients that can amplify or attenuate any climate driven trends in upper ocean nutrient supply.
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- 2020
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16. Developing Autonomous Observing Systems for Micronutrient Trace Metals
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Maxime M. Grand, Agathe Laes-Huon, Susanne Fietz, Joseph A. Resing, Hajime Obata, George W. Luther, Alessandro Tagliabue, Eric P. Achterberg, Rob Middag, Antonio Tovar-Sánchez, and Andrew R. Bowie
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trace metals ,micronutrients ,in situ chemical analyzers ,in situ sensors ,GEOTRACES ,OceanObs’19 ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Trace metal micronutrients are integral to the functioning of marine ecosystems and the export of particulate carbon to the deep ocean. Although much progress has been made in mapping the distributions of metal micronutrients throughout the ocean over the last 30 years, there remain information gaps, most notable during seasonal transitions and in remote regions. The next challenge is to develop in situ sensing technologies necessary to capture the spatial and temporal variabilities of micronutrients characterized with short residence times, highly variable source terms, and sub-nanomolar concentrations in open ocean settings. Such an effort will allow investigation of the biogeochemical processes at the necessary resolution to constrain fluxes, residence times, and the biological and chemical responses to varying metal inputs in a changing ocean. Here, we discuss the current state of the art and analytical challenges associated with metal micronutrient determinations and highlight existing and emerging technologies, namely in situ chemical analyzers, electrochemical sensors, passive preconcentration samplers, and autonomous trace metal clean samplers, which could form the basis of autonomous observing systems for trace metals within the next decade. We suggest that several existing assets can already be deployed in regions of enhanced metal concentrations and argue that, upon further development, a combination of wet chemical analyzers with electrochemical sensors may provide the best compromise between analytical precision, detection limits, metal speciation, and longevity for autonomous open ocean determinations. To meet this goal, resources must be invested to: (1) improve the sensitivity of existing sensors including the development of novel chemical assays; (2) reduce sensor size and power requirements; (3) develop an open-source “Do-It-Yourself” infrastructure to facilitate sensor development, uptake by end-users and foster a mechanism by which scientists can rapidly adapt commercially available technologies to in situ applications; and (4) develop a community-led standardized protocol to demonstrate the endurance and comparability of in situ sensor data with established techniques. Such a vision will be best served through ongoing collaborations between trace metal geochemists, analytical chemists, the engineering community, and commercial partners, which will accelerate the delivery of new technologies for in situ metal sensing in the decade following OceanObs’19.
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- 2019
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17. Southern Ocean Seasonal Cycle Experiment 2012: Seasonal scale climate and carbon cycle links
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Sebastiaan Swart, Nicolette Chang, Nicolas Fauchereau, Warren Joubert, Mike Lucas, Thato Mtshali, Alakendra Roychoudhury, Alessandro Tagliabue, Sandy Thomalla, Howard Waldron, and Pedro Monteiro
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seasonal cycle ,mixed layer depth ,biogeochemistry ,Science ,Science (General) ,Q1-390 ,Social Sciences ,Social sciences (General) ,H1-99 - Published
- 2012
18. Analysis of the global ocean sampling (GOS) project for trends in iron uptake by surface ocean microbes.
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Eve Toulza, Alessandro Tagliabue, Stéphane Blain, and Gwenael Piganeau
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Medicine ,Science - Abstract
Microbial metagenomes are DNA samples of the most abundant, and therefore most successful organisms at the sampling time and location for a given cell size range. The study of microbial communities via their DNA content has revolutionized our understanding of microbial ecology and evolution. Iron availability is a critical resource that limits microbial communities' growth in many oceanic areas. Here, we built a database of 2319 sequences, corresponding to 140 gene families of iron metabolism with a large phylogenetic spread, to explore the microbial strategies of iron acquisition in the ocean's bacterial community. We estimate iron metabolism strategies from metagenome gene content and investigate whether their prevalence varies with dissolved iron concentrations obtained from a biogeochemical model. We show significant quantitative and qualitative variations in iron metabolism pathways, with a higher proportion of iron metabolism genes in low iron environments. We found a striking difference between coastal and open ocean sites regarding Fe(2+) versus Fe(3+) uptake gene prevalence. We also show that non-specific siderophore uptake increases in low iron open ocean environments, suggesting bacteria may acquire iron from natural siderophore-like organic complexes. Despite the lack of knowledge of iron uptake mechanisms in most marine microorganisms, our approach provides insights into how the iron metabolic pathways of microbial communities may vary with seawater iron concentrations.
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- 2012
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19. Multidecadal trend of increasing iron stress in Southern Ocean phytoplankton
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Thomas J. Ryan-Keogh, Sandy J. Thomalla, Pedro M. S. Monteiro, and Alessandro Tagliabue
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Multidisciplinary - Abstract
Southern Ocean primary productivity is principally controlled by adjustments in light and iron limitation, but the spatial and temporal determinants of iron availability, accessibility, and demand are poorly constrained, which hinders accurate long-term projections. We present a multidecadal record of phytoplankton photophysiology between 1996 and 2022 from historical in situ datasets collected by Biogeochemical Argo (BGC-Argo) floats and ship-based platforms. We find a significant multidecadal trend in irradiance-normalized nonphotochemical quenching due to increasing iron stress, with concomitant declines in regional net primary production. The observed trend of increasing iron stress results from changing Southern Ocean mixed-layer physics as well as complex biological and chemical feedback that is indicative of important ongoing changes to the Southern Ocean carbon cycle.
- Published
- 2023
20. Tracing differences in iron supply to the Mid-Atlantic Ridge valley between hydrothermal vent sites: implications for the addition of iron to the deep ocean
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Alastair J. M. Lough, Alessandro Tagliabue, Clément Demasy, Joseph A. Resing, Travis Mellett, Neil J. Wyatt, and Maeve C. Lohan
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Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Abstract
Supply of iron (Fe) to the surface ocean supports primary productivity, and while hydrothermal input of Fe to the deep ocean is known to be extensive it remains poorly constrained. Global estimates of hydrothermal Fe supply rely on using dissolved Fe (dFe) to excess He (xs3He) ratios to upscale fluxes, but observational constraints on dFe/xs3He may be sensitive to assumptions linked to sampling and interpolation. We examined the variability in dFe/xs3He using two methods of estimation, for four vent sites with different geochemistry along the Mid-Atlantic Ridge. At both Rainbow and TAG, the plume was sampled repeatedly and the range of dFe/xs3He was 4 to 63 and 4 to 87 nmol:fmol, respectively, primarily due to differences in plume age. To account for background xs3He and shifting plume position, we calibrated He values using contemporaneous dissolved Mn (dMn). Applying this approach more widely, we found dFe/xs3He ratios of 12, 4–8, 4–44, and 4–86 nmol fmol−1 for the Menez Gwen, Lucky Strike, Rainbow, and TAG hydrothermal vent sites, respectively. Differences in plume dFe/xs3He across sites were not simply related to the vent endmember Fe and He fluxes. Within 40 km of the vents, the dFe/xs3He ratios decreased to 3–38 nmol fmol−1, due to the precipitation and subsequent settling of particulates. The ratio of colloidal Fe to dFe was consistently higher (0.67–0.97) than the deep N. Atlantic (0.5) throughout both the TAG and Rainbow plumes, indicative of Fe exchange between dissolved and particulate phases. Our comparison of TAG and Rainbow shows there is a limit to the amount of hydrothermal Fe released from vents that can form colloids in the rising plume. Higher particle loading will enhance the longevity of the Rainbow hydrothermal plume within the deep ocean assuming particles undergo continual dissolution/disaggregation. Future studies examining the length of plume pathways required to escape the ridge valley will be important in determining Fe supply from slow spreading mid-ocean ridges to the deep ocean, along with the frequency of ultramafic sites such as Rainbow. Resolving the ridge valley bathymetry and accounting for variability in vent sources in global biogeochemical models will be key to further constraining the hydrothermal Fe flux.
- Published
- 2023
21. The footprint of iron-manganese limitation of the biological carbon cycle in a changing climate
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Prima Anugerahanti and Alessandro Tagliabue
- Abstract
The importance of iron in driving net primary production (NPP) and the biological carbon pump across the Southern Ocean has been explored in numerous studies. However, the potential role for manganese, essential to oxygen production and combating oxidative stress, has not received the same attention despite the noted physiological inter-dependencies between iron-manganese and that both are strongly depleted in Southern Ocean. In the sixth climate model intercomparison project, earth system models (ESMs) project increasing NPP in the Southern Ocean due to supply of additional iron, while the global trend shows a decline. Similar mechanisms also describe the role of the ocean carbon cycle during the last glacial maximum. However, under increasing iron supply, more manganese is required to fulfil phytoplankton growth, and the neglect of manganese limitation in ESMs can further increase the uncertainty of future NPP in the Southern Ocean under future or past climate change.Here we use a hierarchy of experiments with the state-of-the-art global ocean biogeochemical model PISCES-QUOTA, including explicit manganese limitation, to explore how the physiological traits govern iron and manganese stress in response to a changing climate. Our results show that manganese is deficient throughout much of the Southern Ocean, but iron is generally the limiting resource. Explicitly representing iron and Mn co-limitation through oxidative stress enhances the extent of manganese deficiency, especially for diatoms. Traits associated with photophysiological adaptation and management of oxidative stress may be unique in Antarctic plankton and are critical in modulating the footprint of both iron and manganese stress and hence the impacts on the carbon cycle in a changing climate. Overall, our results indicate that both iron and manganese are key determinants of the impact of climate change on the Southern Ocean, with a notable role for region-specific adaptive and acclimatory responses that require further constraint.
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- 2023
22. Process controlling iron–manganese regulation of the Southern Ocean biological carbon pump
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Prima Anugerahanti and Alessandro Tagliabue
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General Mathematics ,General Engineering ,General Physics and Astronomy - Abstract
Iron (Fe) is a key limiting nutrient driving the biological carbon pump and is routinely represented in global ocean biogeochemical models. However, in the Southern Ocean, the potential role for other micronutrients has not received the same attention. For example, although manganese (Mn) is essential to photosynthetic oxygen production and combating oxidative stress, it is not included in ocean models and a clear understanding of its interaction with Fe in the region is lacking. This is especially important for the Southern Ocean because both Mn and Fe are strongly depleted. We use a hierarchical modelling approach to explore how the physiological traits associated with Fe and Mn contribute to driving the footprint of micronutrient stress across different phytoplankton functional types (PFTs). We find that PFT responses are driven by physiological traits associated with their physiological requirements and acclimation to environmental conditions. Southern Ocean-specific adaptations to prevailing low Fe, such as large photosynthetic antenna sizes, are of major significance for the regional biological carbon pump. Other traits more strongly linked to Mn, such as dealing with oxidative stress, may become more important under a changing Fe supply regime. This article is part of a discussion meeting issue ‘Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities’.
- Published
- 2023
23. Tracking Improvement in Simulated Marine Biogeochemistry Between CMIP5 and CMIP6
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Roland Seferian, Sarah Berthet, Andrew Yool, Julien Palmieri, Laurent Bopp, Alessandro Tagliabue, Lester Kwiatkowski, Olivier Aumont, James Christian, John Dunne, Marion Gehlen, Tatiana Ilyina, Jasmin G. John, Hongmei L, Matthew C. Long, Jessica Y. Luo, Hideyuki Nakano, Anastasia Romanou, Jörg Schwinger, Charles Stock, Yeray Santana-Falcón, Yohei Takano, Jerry Tjiputra, Hiroyuki Tsujino, Michio Watanabe, Tongwen Wu, Fanghua Wu, and Akitomo Yamamoto
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Meteorology And Climatology - Abstract
Purpose of Review The changes or updates in ocean biogeochemistry component have been mapped between CMIP5 and CMIP6 model versions, and an assessment made of how far these have led to improvements in the simulated mean state of marine biogeochemical models within the current generation of Earth system models (ESMs). Recent Findings The representation of marine biogeochemistry has progressed within the current generation of Earth system models. However, it remains difficult to identify which model updates are responsible for a given improvement. In addition, the full potential of marine biogeochemistry in terms of Earth system interactions and climate feedback remains poorly examined in the current generation of Earth system models. Summary Increasing availability of ocean biogeochemical data, as well as an improved understanding of the underlying processes, allows advances in the marine biogeochemical components of the current generation of ESMs. The present study scrutinizes the extent to which marine biogeochemistry components of ESMs have progressed between the 5th and the 6th phases of the Coupled Model Intercomparison Project (CMIP).
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- 2020
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- View/download PDF
24. The unaccounted dissolved iron (II) sink: Insights from dFe(II) concentrations in the deep Atlantic Ocean
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David González-Santana, Alastair J.M. Lough, Hélène Planquette, Géraldine Sarthou, Alessandro Tagliabue, Maeve C. Lohan, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Oceanografía y Cambio Global (IOCAG), Université de Las Palmas de Gran Canaria [Espagne] (ULPGC), University of Southampton, Centre National de la Recherche Scientifique (CNRS), and University of Liverpool
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[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,Environmental Engineering ,GEOTRACES ,(Min ,Environmental Chemistry ,Biogeochemistry ,Pollution ,Waste Management and Disposal ,Hydrothermal ,Atlantic Ocean ,5-Max ,Iron oxidation ,8) - Abstract
Hydrothermal vent sites found along mid-ocean ridges are sources of numerous reduced chemical species and trace elements. To establish dissolved iron (II) (dFe(II)) variability along the Mid Atlantic Ridge (between 39.5 degrees N and 26 degrees N), dFe(II) concentrations were measured above six hydrothermal vent sites, as well as at stations with no active hydrothermal activity. The dFe(II) concentrations ranged from 0.00 to 0.12 nmol L-1 (detection limit = 0.02 +/- 0.02 nmol L-1) in non-hydrothermally affected regions to values as high as 12.8 nmol L-1 within hydrothermal plumes. Iron (II) in seawater is oxidised over a period of minutes to hours, which is on average two times faster than the time required to collect the sample from the deep ocean and its analysis in the onboard laboratory. A multiparametric equation was used to estimate the original dFe(II) concentration in the deep ocean. The in-situ temperature, pH, salinity and delay between sample collection and its analysis were considered. The results showed that dFe(II) plays a more significant role in the iron pool than previously accounted for, constituting a fraction >20 % of the dissolved iron pool, in contrast to
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- 2023
25. Multi‐decadal environmental change in the Barents Sea recorded by seal teeth
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Camille de la Vega, Pearse J. Buchanan, Alessandro Tagliabue, Joanne E. Hopkins, Rachel M. Jeffreys, Anne Kirstine Frie, Martin Biuw, Joanna Kershaw, James Grecian, Louisa Norman, Sophie Smout, Tore Haug, Claire Mahaffey, University of St Andrews. School of Biology, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Centre for Research into Ecological & Environmental Modelling, and University of St Andrews. Coastal Resources Management Group
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GC ,Global and Planetary Change ,Food Chain ,Ecology ,Arctic Regions ,Seals, Earless ,DAS ,Caniformia ,Atmospheric nitrogen deposition, harp seal ,Arctic ,Stable nitrogen isotopes ,Animals ,Environmental Chemistry ,GC Oceanography ,SDG 14 - Life Below Water ,Atlantification ,Ecosystem ,General Environmental Science - Abstract
This work resulted from the ARISE project (NE/P006035/1, NE/P006000/1), part of the Changing Arctic Ocean programme, jointly funded by the UKRI Natural Environment Research Council (NERC). We thank Jim Ball for his help in the isotopic lab in Liverpool University. This work resulted from the ARISE project, part of the Changing Arctic Ocean programme. Multiple environmental forcings, such as warming and changes in ocean circulation and nutrient supply, are affecting the base of Arctic marine ecosystems, with cascading effects on the entire food web through bottom-up control. Stable nitrogen isotopes (δ15N) can be used to detect and unravel the impact of these forcings on this unique ecosystem, if the many processes that affect the δ15N values are constrained. Combining unique 60-year records from compound specific δ15N biomarkers on harp seal teeth alongside state-of-the-art ocean modelling, we observed a significant decline in the δ15N values at the base of the Barents Sea food web from 1951 to 2012. This strong and persistent decadal trend emerges due to the combination of anthropogenic atmospheric nitrogen deposition in the Atlantic, increased northward transport of Atlantic water through Arctic gateways and local feedbacks from increasing Arctic primary production. Our results suggest that the Arctic ecosystem has been responding to anthropogenically induced local and remote drivers, linked to changing ocean biology, chemistry and physics, for at least 60 years. Accounting for these trends in δ15N values at the base of the food web is essential to accurately detect ecosystem restructuring in this rapidly changing environment. Publisher PDF
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- 2022
26. Microbial siderophore production is tightly coupled to iron in hydrothermal plumes
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Colleen L. Hoffman, Patrick J. Monreal, Justine B. Albers, Alastair J.M. Lough, Alyson E. Santoro, Travis Mellett, Kristen N. Buck, Alessandro Tagliabue, Maeve C. Lohan, Joseph A. Resing, and Randelle M. Bundy
- Abstract
Specialized molecules, such as siderophores, are used to access and retain iron in soluble forms by marine microorganisms. These siderophores form part of the ocean dissolved iron-binding ligand pool and are hypothesized to exert a key control on the persistence of iron in hydrothermal environments. To explore this hypothesis, we measured iron, iron-binding ligands, and siderophores from 11 geochemically distinct sites along a 1,700 km section of the Mid-Atlantic Ridge. We found siderophores at all sites and proximity to the vent played an important role in dictating siderophore types and diversity. The notable presence of amphiphilic siderophores may enable microbes to access particulate iron in hydrothermal plumes. The tight coupling between strong ligands and dissolved iron across six distinct hydrothermal environments, combined with the local presence of siderophore producing microbial genera suggests that biological production of siderophores exerts a key control on hydrothermal dissolved iron concentrations.
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- 2023
27. The Fingerprint of Climate Variability on the Surface Ocean Cycling of Iron and its Isotopes
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Daniela König and Alessandro Tagliabue
- Abstract
The essential micronutrient iron (Fe) limits phytoplankton growth when dissolved Fe (dFe) concentrations are too low to meet biological demands. However, many of the processes that remove, supply, or transform Fe are poorly constrained, which limits our ability to predict how ocean productivity responds to ongoing and future changes in climate. In recent years, isotopic signatures (ẟ56Fe) of Fe have increasingly been used to gain insight into the ocean Fe cycle, as distinct ẟ56Fe endmembers of external Fe sources and ẟ56Fe fractionation during processes such as Fe uptake by phytoplankton can leave a characteristic imprint on dFe signatures (ẟ56Fediss). However, given the relative novelty of these measurements, the temporal scale of ẟ56Fediss observations is limited. Thus, it is unclear how the changes in ocean physics and biogeochemistry associated with ongoing or future climate change will affect ẟ56Fediss on interannual to decadal time scales. To explore the response of ẟ56Fediss to such climate variability, we conducted a suite of experiments with a global ocean model with active ẟ56Fe cycling under two climate scenarios. The first scenario is based on an atmospheric reanalysis and includes recent climate variability (1958–2021), whereas the second comes from a historical and high emissions climate change simulation to 2100. We find that under recent climatic conditions (1975–2021), interannual ẟ56Fediss variability is highest in the tropical Pacific due to circulation and productivity changes related to the El Niño Southern Oscillation (ENSO), which alter both endmember and uptake fractionation effects on ẟ56Fediss by redistributing dFe from different external sources and shifting nutrient limitation patterns. While the tropical Pacific remains a hotspot of ẟ56Fediss variability in the future, the most substantial end of century ẟ56Fediss changes occur in the Southern hemisphere at mid to high latitudes. These arise from uptake fractionation effects due to shifts in nutrient limitation. Based on these strong responses to climate variability, ongoing measurements of ẟ56Fediss may help diagnose changes in external Fe supply and ocean nutrient limitation.
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- 2023
28. Supplementary material to 'The Fingerprint of Climate Variability on the Surface Ocean Cycling of Iron and its Isotopes'
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Daniela König and Alessandro Tagliabue
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- 2023
29. A Biogeography of Zooplankton Stress Factors in the Global Ocean
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Camille Richon, Charlotte Wagner, Elsie Sunderland, and Alessandro Tagliabue
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- 2023
30. Mechanisms Driving the Dispersal of Hydrothermal Iron From the Northern Mid Atlantic Ridge
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Alessandro Tagliabue, Alastair J. M. Lough, Clément Vic, Vassil Roussenov, Jonathan Gula, Maeve C. Lohan, Joseph A. Resing, Richard G. Williams, University of Liverpool, University of Leeds, University of Southampton, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Océan Dynamique Observations Analyse (ODYSSEY), Université de Bretagne Occidentale - UFR Sciences et Techniques (UBO UFR ST), Université de Brest (UBO)-Université de Brest (UBO)-Université de Rennes (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), University of Washington [Seattle], and ANR-19-CE01-0002,DEEPER,Impacts de la turbulence de sous-mésoéchelle profonde sur la circulation océanique(2019)
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iron ,Geophysics ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,biogeochemistry ,hydrothermalism ,General Earth and Planetary Sciences ,modeling ,ocean ,[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography - Abstract
International audience; The dispersal of dissolved iron (DFe) from hydrothermal vents is poorly constrained. Combining field observations and a modeling hierarchy, we find the dispersal of DFe from the Trans-Atlantic-Geotraverse vent site occurs predominantly in the colloidal phase and is controlled by multiple physical processes. Enhanced mixing near the seafloor and transport through fracture zones at fine-scales interacts with the wider ocean circulation to drive predominant westward DFe dispersal away from the Mid-Atlantic ridge at the 100 km scale. In contrast, diapycnal mixing predominantly drives northward DFe transport within the ridge axial valley. The observed DFe dispersal is not reproduced by the coarse resolution ocean models typically used to assess ocean iron cycling due to their omission of local topography and mixing. Unless biogeochemical models account for fine-scale physics and colloidal Fe, they will inaccurately represent DFe dispersal from axial valley ridge systems, which make up half of the global ocean ridge crest.
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- 2022
31. Iron Cycle in Oceans
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Stéphane Blain, Alessandro Tagliabue and Stéphane Blain, Alessandro Tagliabue
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- 2016
32. Compound climate risks threaten aquatic food system benefits
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Alessandro Tagliabue, Vicky W. Y. Lam, Rosamond L. Naylor, U. Rashid Sumaila, Elizabeth R. Selig, Michael Phillips, Essam Yassin Mohammed, Colette C. C. Wabnitz, Ling Cao, Fiorenza Micheli, Max Troell, Abigail Bennett, Michelle Tigchelaar, Benjamin S. Halpern, Jessica Fanzo, Hanna J. Payne, Thomas L. Frölicher, Christopher D. Golden, Jessica A. Gephart, Muhammed A. Oyinlola, Edward H. Allison, and William W. L. Cheung
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Sustainable development ,Natural resource economics ,Climate risk ,media_common.quotation_subject ,Climate change ,Climate resilience ,Livelihood ,Food systems ,Animal Science and Zoology ,Psychological resilience ,Business ,Small Island Developing States ,Agronomy and Crop Science ,Food Science ,media_common - Abstract
Aquatic foods from marine and freshwater systems are critical to the nutrition, health, livelihoods, economies and cultures of billions of people worldwide, but climate-related hazards may compromise their ability to provide these benefits. Here, we estimate national-level aquatic food system climate risk using an integrative food systems approach that connects climate hazards impacting marine and freshwater capture fisheries and aquaculture to their contributions to sustainable food system outcomes. We show that without mitigation, climate hazards pose high risks to nutritional, social, economic and environmental outcomes worldwide—especially for wild-capture fisheries in Africa, South and Southeast Asia, and Small Island Developing States. For countries projected to experience compound climate risks, reducing societal vulnerabilities can lower climate risk by margins similar to meeting Paris Agreement mitigation targets. System-level interventions addressing dimensions such as governance, gender equity and poverty are needed to enhance aquatic and terrestrial food system resilience and provide investments with large co-benefits towards meeting the Sustainable Development Goals. The nutritional, economic and livelihood contributions provided by aquatic food systems are threatened by climate change. Building climate resilience requires systemic interventions that reduce social vulnerabilities.
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- 2021
33. Integrating the impact of global change on the niche and physiology of marine nitrogen-fixing cyanobacteria
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Lewis Wrightson, Nina Yang, Claire Mahaffey, David A. Hutchins, and Alessandro Tagliabue
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Global and Planetary Change ,Ecology ,Nitrogen ,Nitrogen Fixation ,Environmental Chemistry ,Seawater ,Phosphorus ,Cyanobacteria ,General Environmental Science - Abstract
Marine nitrogen fixation is a major source of new nitrogen to the ocean, which interacts with climate driven changes to physical nutrient supply to regulate the response of ocean primary production in the oligotrophic tropical ocean. Warming and changes in nutrient supply may alter the ecological niche of nitrogen-fixing organisms, or 'diazotrophs', however, impacts of warming on diazotroph physiology may also be important. Lab-based studies reveal that warming increases the nitrogen fixation-specific elemental use efficiency (EUE) of two prevalent marine diazotrophs, Crocosphaera and Trichodesmium, thus reducing their requirements for the limiting nutrients iron and phosphorus. Here, we coupled a new diazotroph model based upon observed diazotroph energetics of growth and resource limitation to a state-of-the-art global model of phytoplankton physiology and ocean biogeochemistry. Our model is able to address the integrated response of nitrogen fixation by Trichodesmium and Crocosphaera to warming under the IPCC high emission RCP8.5 scenario for the first time. Our results project a global decline in nitrogen fixation over the coming century. However, the regional response of nitrogen fixation to climate change is modulated by the diazotroph-specific thermal performance curves and EUE, particularly in the Pacific Ocean, which shapes global trends. Spatially, the response of both diazotrophs is similar with expansion towards higher latitudes and reduced rates of nitrogen fixation in the lower latitudes. Overall, 95%-97% of the nitrogen fixation climate signal can be attributed to the combined effect of temperature on the niche and physiology of marine diazotrophs, with decreases being associated with a reduced niche and increases resulting due to a combination of expanding niche and temperature driven changes to EUE. Climate change impacts on both the niche and physiology of marine diazotrophs interact to shape patterns of marine nitrogen fixation, which will have important implications for ocean productivity in the future.
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- 2022
34. Examining the Interaction Between Free‐Living Bacteria and Iron in the Global Ocean
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Alessandro Tagliabue, Lavenia Ratnarajah, Olivier Aumont, Anh Le-Duy Pham, Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), School of Environmental Sciences [Durban], University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN), and ANR-17-CE32-0008,CIGOEF,Impacts des changements climatiques sur les écosystèmes et les pêcheries océaniques globaux.(2017)
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Atmospheric Science ,Global and Planetary Change ,fungi ,Environmental Chemistry ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,General Environmental Science - Abstract
International audience; Marine free-living (FL) bacteria play a key role in the cycling of essential biogeochemical elements, including iron (Fe), during their uptake, transformation and release of organic matter throughout the water column. Similar to phytoplankton, the growth of FL bacteria is regulated by nutritive resources such as Fe, and the low availability of these resources may influence bacterial interactions with phytoplankton, causing knock-on effects for biogeochemical cycling. Yet, knowledge of the factors limiting the growth of FL bacteria and their role within the Fe cycle is poorly constrained. Here, we explicitly represent FL, carbon-oxidizing bacteria in a three-dimensional global ocean biogeochemistry model to address these questions. We find that although Fe can emerge as proximally limiting in the tropical Pacific and in high-latitude regions during summer, the growth of FL bacteria is ultimately controlled by the availability of labile dissolved organic carbon over most of the world's oceans. In Fe-limited regions, FL bacterial biomass is sensitive to their Fe uptake capability in seasonally Fe-limitation regions and to their minimum Fe requirements in regions perennially low in Fe. Fe consumption by FL bacteria is significant in the upper ocean in our model, and their competition with phytoplankton for Fe affects phytoplankton growth dynamics and can make bacteria become more carbon limited. The impact of FL bacteria on the Fe distribution in the ocean interior is small due to a tight coupling between Fe uptake and release. Moving forward, future work that considers other bacteria groups and different bacterial metabolisms is needed to explore the broader role of bacteria in ocean Fe cycling. In this context, the global growing’ omics data from ocean observing programs can play a crucial role.
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- 2022
35. Taxonomic and nutrient controls on phytoplankton iron quotas in the ocean
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Olga Antipova, Adrian Marchetti, Sara Rauschenberg, Daniel C. Ohnemus, Elizabeth L. Mann, Alessandro Tagliabue, P. Dreux Chappell, Jeremy E. Jacquot, Natalie R. Cohen, and Benjamin S. Twining
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0106 biological sciences ,Biomass (ecology) ,Nutrient cycle ,010504 meteorology & atmospheric sciences ,Ecology ,010604 marine biology & hydrobiology ,fungi ,Biogeochemistry ,Aquatic Science ,Plankton ,Oceanography ,01 natural sciences ,Pacific ocean ,lcsh:Oceanography ,Nutrient ,Phytoplankton ,Environmental science ,lcsh:GC1-1581 ,14. Life underwater ,0105 earth and related environmental sciences - Abstract
Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of the low‐iron Pacific Ocean. Among diatoms, both pennate and centric genera accumulated luxury iron, but the cosmopolitan pennate genus Pseudo‐nitzschia maintained iron quotas 10‐fold higher than co‐occurring centric diatoms, likely due to enhanced iron storage. Biogeochemical models should account for taxonomic and macronutrient controls on phytoplankton iron quotas.
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- 2020
36. The impact of hydrothermal vent geochemistry on the addition of iron to the deep ocean
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Alastair Jason Mackenzie Lough, Alessandro Tagliabue, Clement Demasy, Joseph A. Resing, Travis Mellett, Neil J. Wyatt, and Maeve C. Lohan
- Abstract
Supply of iron (Fe) to the surface ocean supports primary productivity and while hydrothermal input of Fe to the deep ocean is known to be extensive, it remains poorly constrained. Global estimates of hydrothermal Fe supply rely on using the dissolved Fe (dFe) to excess He (xs3He) ratios to upscale fluxes, but observational constraints on dFe / xs3He may be sensitive to assumptions linked to sampling and interpolation. We examined the variability in dFe / xs3He using two methods of estimation, for four vent sites with different geochemistry along the Mid-Atlantic Ridge. At both Rainbow and TAG, the plume was sampled repeatedly and the range of dFe / xs3He was 4 to 63 and 4 to 87 nmol/fmol, respectively, primarily due to differences in plume age. To account for background xs3He and shifting plume position, we calibrated He values using contemporaneous dissolved Mn (dMn). Applying this approach more widely, we found dFe / xs3He ratios of 12, 4–8, 4–44, 4–86 nmol/fmol for the Menez Gwen, Lucky Strike, Rainbow and TAG hydrothermal vent sites, respectively. Differences in plume dFe / xs3He across sites were not simply related to the vent end member Fe and He fluxes. Within 40 km of the vents, the dFe / xs3He ratios decreased to 3-38 nmol/fmol, due to the precipitation and subsequent settling of particulates. The ratio of colloidal Fe to dFe was consistently higher (0.67–0.97) than the deep N. Atlantic (0.5) throughout both the TAG and Rainbow plumes, indicative of Fe exchange between dissolved and particulate phases. Our comparison of TAG and Rainbow shows there is a limit to the amount of hydrothermal Fe released from vents that can form colloids in the rising plume. Higher particle loading will enhance the longevity of the Rainbow hydrothermal plume within the deep ocean assuming particles undergo continual dissolution/disaggregation. Future studies examining the length of plume pathways required to escape the ridge valley will be important in determining Fe supply from slow spreading mid-ocean ridges to the deep ocean, along with the frequency of ultramafic sites such as Rainbow. Resolving the ridge valley bathymetry and accounting for variability in vent sources in global biogeochemical models will be key to further constraining the hydrothermal Fe flux.
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- 2022
37. Supplementary material to 'The impact of hydrothermal vent geochemistry on the addition of iron to the deep ocean'
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Alastair Jason Mackenzie Lough, Alessandro Tagliabue, Clement Demasy, Joseph A. Resing, Travis Mellett, Neil J. Wyatt, and Maeve C. Lohan
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- 2022
38. Projecting net primary production in a sea of uncertainty: next steps and why should we care?
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Laurent Bopp, Olivier Aumont, Lester Kwiatkowski, Priscilla Le Mezo, Olivier Maury, Roland Séférian, and Alessandro Tagliabue
- Abstract
Ocean net primary production (NPP) consists of CO2 fixation by marine phytoplankton and hence supports most marine food webs, fisheries and ocean carbon sequestration. Recent Earth System Model (ESM) projections of NPP changes under global warming scenarios, performed as part of the 6th phase of Coupled Model Intercomparison Project (CMIP6), show large uncertainty both in the magnitude and spatial distribution of NPP, which may have consequences for assessing ecosystem impacts and ocean carbon uptake. NPP uncertainty has increased since the previous intercomparion project (CMIP5), and likely does not even capture the full range of possible outcomes due to the general simplicity of ecosystem parameterizations employed in ESMs and the failure to account for non-climate drivers. Here, we exploit the full set of ESM projections from CMIP6, documenting NPP uncertainties and identifying certain physical and biogeochemical mechanisms that give rise to these uncertainties. We then use different versions of the IPSL ESM to explore (1) the specific role of N-fixation by diazotrophs in the upper ocean and (2) the influence of coupling to higher trophic levels in shaping the response of NPP, marine ecosystems and biogeochemistry to anthropogenic climate change. We show that the response of N-fixation to global warming is a key driver of NPP projection uncertainties in the coming decades, even determining the sign of the global NPP response. Despite contrasting projections of future NPP, all our model versions simulate similar and significant reductions in planktonic biomass. This suggests that plankton biomass may be a more robust indicator than NPP of the potential impact of anthropogenic climate change on marine ecosystems across models. In a second step, we show that an explicit coupling to higher trophic levels modifies the response of lower trophic levels (plankton) and shifts the ecosystem equilibrium, but seems to have limited influence on 21st century anthropogenic carbon uptake under the RCP8.5 high emissions scenario. These results provide new insights regarding the expectations for trophic amplification of climate impacts through the marine food chain and regarding the necessity to explicitly represent marine animals in Earth System Models.
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- 2022
39. Surface ocean biogeochemistry regulates the impact of anthropogenic aerosol Fe deposition on iron and iron isotopes in the North Pacific
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Daniela König, Tim Conway, Douglas Hamilton, and Alessandro Tagliabue
- Abstract
Long-range atmospheric transport and deposition of anthropogenically-sourced aerosol iron (Fe) affects surface ocean biogeochemistry far from the emission source. However, it is challenging to establish the integrated impact of anthropogenic aerosol Fe on surface ocean dissolved Fe (dFe) cycling, due to other Fe sources and in situ cycling processes. Previous work has used a distinctively-light Fe isotopic signature (δ56Fe) associated with anthropogenic activity to track the contribution of anthropogenic Fe at the basin scale. However, this requires not only the determination of the δ56Fe endmember of all potential Fe sources, but also the assessment of how upper ocean biogeochemical cycling modulates surface ocean dFe signatures (δ56Fediss). Here we accounted for dust, fire and anthropogenic Fe deposition fields in a global ocean biogeochemical model with an integrated δ56Fecycle to quantify the impact of anthropogenic Fe on surface ocean Fe and δ56Fe, with a focus on the North Pacific. The effect of anthropogenic Fe is spatially distinct and seasonally variable in our model, depending on the biogeochemical state of the upper ocean. In the subtropical regions where Fe is not limiting, anthropogenic Fe input leads to increased dFe levels and, at times, phytoplankton Fe uptake. δ56Fediss declines due to the very light anthropogenic δ56Fe endmember, most prominently in low dFe areas of the subtropical North Pacific gyre. In Fe-limited systems, such as the subpolar gyre, anthropogenic Fe stimulates both primary production and Fe uptake with little change to summertime dFe levels. Moreover, the decrease in δ56Fediss is amplified as extra Fe dampens the impact of the fractionation effects associated with Fe uptake and complexation, whereby the overall δ56Fediss often remains positive. Overall, it is important to account for biological parameters, such as primary productivity or Fe limitation, when assessing the oceanic impact of anthropogenic Fe.
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- 2022
40. Data-driven modeling of dissolved iron in the global ocean
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Nicolas Cassar, Yibin Huang, Alessandro Tagliabue, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)
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Global and Planetary Change ,data-driven model ,Ocean Engineering ,Aquatic Science ,Oceanography ,ocean biogeochemistry ,dissolved iron ,machining learning ,[SDE]Environmental Sciences ,controlling mechanism ,monthly climatology ,Water Science and Technology - Abstract
Global climatological map of dissolved iron in the global ocean from publication: "Data-driven modeling of dissolved iron in the global ocean" by Huang et al. 2022. File Monthly_dFe.nc (NC_FORMAT_CLASSIC): 1 variable (excluding dimension variables): double dFe_RF [Longitude, Latitude, Depth, Month] units: nmol L-1 FillValue: NaN long_name: Monthly dissolved iron simulated from random forest algorithm coordinates: [Longitude, Latitude, Depth, Month] 4 dimensions: Longitude Size:357 units: degree_north long_name: Longitude Latitude Size:147 units: degree_east long_name: Latitude Depth Size:31 units: meter long_name: Depth Month Size:13 Units: "Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec", "Annuual mean" long_name: Month 4 global attributes: Author: Yibin Huang & Nicolas Cassar Correspond: nicolas.cassar@duke.edu Request_for_citation: If you use these data in publications or presentations, please cite: “Huang, Y., Tagliabue, A., & Cassar, N. (2022). Data-driven modeling of dissolved iron in the global ocean. Frontiers in Marine Science. doi:10.3389/fmars.2022.837183”. Creation date: March/20th/2022  
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- 2022
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41. Manganese Limitation of Phytoplankton Physiology and Productivity in the Southern Ocean
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Alessandro Tagliabue, Nicholas Hawco, and Benjamin Twining
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Atmospheric Science ,Global and Planetary Change ,Environmental Chemistry ,General Environmental Science - Published
- 2022
42. Elevated sources of cobalt in the Arctic Ocean
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Mak A. Saito, Peter L. Morton, Randelle M. Bundy, Abigail E. Noble, Benjamin S. Twining, Jay T. Cullen, Seth G. John, Alessandro Tagliabue, Mattias R. Cape, Nicholas J. Hawco, and Mariko Hatta
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0106 biological sciences ,Biogeochemical cycle ,010504 meteorology & atmospheric sciences ,Geotraces ,lcsh:Life ,Permafrost ,Deep sea ,01 natural sciences ,lcsh:QH540-549.5 ,Phytoplankton ,Sea ice ,14. Life underwater ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes ,0105 earth and related environmental sciences ,geography ,geography.geographical_feature_category ,010604 marine biology & hydrobiology ,North Atlantic Deep Water ,fungi ,lcsh:QE1-996.5 ,lcsh:Geology ,lcsh:QH501-531 ,Oceanography ,Arctic ,13. Climate action ,Environmental science ,lcsh:Ecology ,geographic locations - Abstract
Cobalt (Co) is an important bioactive trace metal that is the metal cofactor in cobalamin (vitamin B12) which can limit or co-limit phytoplankton growth in many regions of the ocean. Total dissolved and labile Co measurements in the Canadian sector of the Arctic Ocean during the U.S. GEOTRACES Arctic expedition (GN01) and the Canadian International Polar Year GEOTRACES expedition (GIPY14) revealed a dynamic biogeochemical cycle for Co in this basin. The major sources of Co in the Arctic were from shelf regions and rivers, with only minimal contributions from other freshwater sources (sea ice, snow) and eolian deposition. The most striking feature was the extremely high concentrations of dissolved Co in the upper 100 m, with concentrations routinely exceeding 800 pmol L−1 over the shelf regions. This plume of high Co persisted throughout the Arctic basin and extended to the North Pole, where sources of Co shifted from primarily shelf-derived to riverine, as freshwater from Arctic rivers was entrained in the Transpolar Drift. Dissolved Co was also strongly organically complexed in the Arctic, ranging from 70 % to 100 % complexed in the surface and deep ocean, respectively. Deep-water concentrations of dissolved Co were remarkably consistent throughout the basin (∼55 pmol L−1), with concentrations reflecting those of deep Atlantic water and deep-ocean scavenging of dissolved Co. A biogeochemical model of Co cycling was used to support the hypothesis that the majority of the high surface Co in the Arctic was emanating from the shelf. The model showed that the high concentrations of Co observed were due to the large shelf area of the Arctic, as well as to dampened scavenging of Co by manganese-oxidizing (Mn-oxidizing) bacteria due to the lower temperatures. The majority of this scavenging appears to have occurred in the upper 200 m, with minimal additional scavenging below this depth. Evidence suggests that both dissolved Co (dCo) and labile Co (LCo) are increasing over time on the Arctic shelf, and these limited temporal results are consistent with other tracers in the Arctic. These elevated surface concentrations of Co likely lead to a net flux of Co out of the Arctic, with implications for downstream biological uptake of Co in the North Atlantic and elevated Co in North Atlantic Deep Water. Understanding the current distributions of Co in the Arctic will be important for constraining changes to Co inputs resulting from regional intensification of freshwater fluxes from ice and permafrost melt in response to ongoing climate change.
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- 2020
43. Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs
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Anaïs Médieu, David Point, Takaaki Itai, Hélène Angot, Pearse J. Buchanan, Valérie Allain, Leanne Fuller, Shane Griffiths, David P. Gillikin, Jeroen E. Sonke, Lars-Eric Heimbürger-Boavida, Marie-Maëlle Desgranges, Christophe E. Menkes, Daniel J. Madigan, Pablo Brosset, Olivier Gauthier, Alessandro Tagliabue, Laurent Bopp, Anouk Verheyden, Anne Lorrain, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Department of Earth and Planetary Science [Tokyo], Graduate School of Science [Tokyo], The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo), Extreme Environments Research Laboratory (EERL), Ecole Polytechnique Fédérale de Lausanne (EPFL), Department of Earth Ocean and Ecological Sciences [Liverpool], University of Liverpool, Communauté du Pacifique/Pacific Community, Inter-American Tropical Tuna Commission (IATTC), Union College, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Ecologie marine tropicale dans les Océans Pacifique et Indien (ENTROPIE [Réunion]), Institut de Recherche pour le Développement (IRD)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), University of Windsor [Ca], Dynamique et durabilité des écosystèmes : de la source à l’océan (DECOD), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut de Recherche pour le Développement (IRD), ANR-17-CE34-0010 MERTOX, ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), ANR-17-CE34-0010,MERTOX,Découvrir l'origine de la toxine methylmercure dans les écosystèmes marins(2017), Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Oceanic Fisheries Programme, INSU Division Technique de l'INSU [Site de Brest], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Windsor, Windsor, ON, N9B 3P4, Canada, Université de Brest (UBO), and PacificFundVACOPA Project (spatial VAriations of COntaminants levels in PAcificoceantrophic webs)
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Geologic Sediments ,Asia ,Food Chain ,010504 meteorology & atmospheric sciences ,[SDV]Life Sciences [q-bio] ,[SDE.MCG]Environmental Sciences/Global Changes ,skipjack tuna ,010501 environmental sciences ,01 natural sciences ,Sustainability Science ,Methylation ,atmospheric inputs ,spatial modeling ,biogeochemistry ,Animals ,Humans ,Seawater ,Water Pollutants ,14. Life underwater ,0105 earth and related environmental sciences ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,Multidisciplinary ,Pacific Ocean ,Ecology ,Tuna ,food and beverages ,methylmercury ,Methylmercury ,Mercury ,Biological Sciences ,Methylmercury Compounds ,Models, Theoretical ,Europe ,Seafood ,13. Climate action ,North America ,[SDE]Environmental Sciences ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,human activities ,Environmental Sciences ,Water Pollutants, Chemical ,Environmental Monitoring - Abstract
Significance Humans are exposed to toxic methylmercury mainly by consuming marine fish. New environmental policies under the Minamata Convention rely on a yet-poorly-known understanding of how mercury emissions translate into fish methylmercury levels. Here, we provide the first detailed map of mercury concentrations from skipjack tuna across the Pacific. Our study shows that the natural functioning of the global ocean has an important influence on tuna mercury concentrations, specifically in relation to the depth at which methylmercury concentrations peak in the water column. However, mercury inputs originating from anthropogenic sources are also detectable, leading to enhanced tuna mercury levels in the northwestern Pacific Ocean that cannot be explained solely by oceanic processes., Pacific Ocean tuna is among the most-consumed seafood products but contains relatively high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury levels vary in space and time, yet the drivers are not well understood. Here, we map mercury concentrations in skipjack tuna across the Pacific Ocean and build generalized additive models to quantify the anthropogenic, ecological, and biogeochemical drivers. Skipjack mercury levels display a fivefold spatial gradient, with maximum concentrations in the northwest near Asia, intermediate values in the east, and the lowest levels in the west, southwest, and central Pacific. Large spatial differences can be explained by the depth of the seawater methylmercury peak near low-oxygen zones, leading to enhanced tuna mercury concentrations in regions where oxygen depletion is shallow. Despite this natural biogeochemical control, the mercury hotspot in tuna caught near Asia is explained by elevated atmospheric mercury concentrations and/or mercury river inputs to the coastal shelf. While we cannot ignore the legacy mercury contribution from other regions to the Pacific Ocean (e.g., North America and Europe), our results suggest that recent anthropogenic mercury release, which is currently largest in Asia, contributes directly to present-day human mercury exposure.
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- 2022
44. Earth, Wind, Fire, and Pollution: Aerosol Nutrient Sources and Impacts on Ocean Biogeochemistry
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Robert Wagner, Stelios Myriokefalitakis, Douglas S. Hamilton, Willy Maenhaut, Nazli Olgun, Kerstin Schepanski, Andrew R. Bowie, Rebecca R. Buchholz, Tami C. Bond, Natalie M. Mahowald, Morgane M. G. Perron, Alessandro Tagliabue, Cécile Guieu, Sagar D. Rathod, Akinori Ito, Department of Earth and Atmospheric Sciences [Ithaca) (EAS), Cornell University [New York], University of Illinois at Urbana Champaign (UIUC), University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Atmospheric Chemistry Observations and Modeling Laboratory (ACOML), National Center for Atmospheric Research [Boulder] (NCAR), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Universiteit Gent = Ghent University [Belgium] (UGENT), Environmental Chemical Processes Laboratory [Heraklion] (ECPL), Department of Chemistry [Heraklion], and University of Crete [Heraklion] (UOC)-University of Crete [Heraklion] (UOC)
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Pollution ,010504 meteorology & atmospheric sciences ,Oceans and Seas ,media_common.quotation_subject ,Wind ,010501 environmental sciences ,Oceanography ,01 natural sciences ,Phytoplankton ,Ecosystem ,Marine ecosystem ,14. Life underwater ,0105 earth and related environmental sciences ,media_common ,Aerosols ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,Atmosphere ,Biogeochemistry ,Biota ,Nutrients ,15. Life on land ,Earth system science ,Deposition (aerosol physics) ,13. Climate action ,Environmental science - Abstract
International audience; A key Earth system science question is the role of atmospheric deposition in supplying vital nutrients to the phytoplankton that form the base of marine food webs. Industrial and vehicular pollution, wildfires, volcanoes, biogenic debris, and desert dust all carry nutrients within their plumes throughout the globe. In remote ocean ecosystems, aerosol deposition represents an essential new source of nutrients for primary production. The large spatiotemporal variability in aerosols from myriad sources combined with the differential responses of marine biota to changing fluxes makes it crucially important to understand where, when, and how much nutrients from the atmosphere enter marine ecosystems. This review brings together existing literature, experimental evidence of impacts, and new atmospheric nutrient observations that can be compared with atmospheric and ocean biogeochemistry modeling. We evaluate the contribution and spatiotemporal variability of nutrient-bearing aerosols from desert dust, wildfire, volcanic, and anthropogenic sources, including the organic component, deposition fluxes, and oceanic impacts. Expected final online publication date for the Annual Review of Marine Science, Volume 14 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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- 2022
45. Timing and magnitude of climate‐driven range shifts in transboundary fish stocks challenge their management
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Juliano Palacios‐Abrantes, Thomas L. Frölicher, Gabriel Reygondeau, U. Rashid Sumaila, Alessandro Tagliabue, Colette C. C. Wabnitz, and William W. L. Cheung
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Global and Planetary Change ,Conservation of Natural Resources ,Ecology ,530 Physics ,Climate Change ,Oceans and Seas ,Fisheries ,Fishes ,550 Earth sciences & geology ,Environmental Chemistry ,Animals ,Ecosystem ,General Environmental Science - Abstract
Climate change is shifting the distribution of shared fish stocks between neighboring countries' Exclusive Economic Zones (EEZs) and the high seas. The timescale of these transboundary shifts determines how climate change will affect international fisheries governance. Here, we explore this timescale by coupling a large ensemble simulation of an Earth system model under a high emission climate change scenario to a dynamic population model. We show that by 2030, 23% of transboundary stocks will have shifted and 78% of the world's EEZs will have experienced at least one shifting stock. By the end of this century, projections show a total of 45% of stocks shifting globally and 81% of EEZs waters with at least one shifting stock. The magnitude of such shifts is reflected in changes in catch proportion between EEZs sharing a transboundary stock. By 2030, global EEZs are projected to experience an average change of 59% in catch proportion of transboundary stocks. Many countries that are highly dependent on fisheries for livelihood and food security emerge as hotspots for transboundary shifts. These hotspots are characterized by early shifts in the distribution of an important number of transboundary stocks. Existing international fisheries agreements need to be assessed for their capacity to address the social-ecological implications of climate-change-driven transboundary shifts. Some of these agreements will need to be adjusted to limit potential conflict between the parties of interest. Meanwhile, new agreements will need to be anticipatory and consider these concerns and their associated uncertainties to be resilient to global change.El cambio climático está afectando la distribución de las poblaciones de fauna marina compartidas por Zonas Económicas Exclusivas (ZEEs) de países vecinos y en el alta mar. Los efectos del cambio climático en el manejo pesquero internacional estarán determinados por la escala temporal de dichos desplazamientos transfronterizos. Para determinar esa escala temporal, el presente estudio combinó un modelo dinámico poblacional, con una serie de simulaciones de un modelo del sistema terrestre, bajo un escenario de cambio climático de altas emisiones. Los resultados siguieren que para 2030, el 23% de las poblaciones transfronterizas se habrán desplazado y en el 78% de las ZEEs del mundo habrán experimentado cambios en la distribución de al menos una población transfronteriza. Para fines de este siglo, las proyecciones muestran que el 81% de las ZEEs tendrán al menos una población en movimiento y 45% de las poblaciones transfronterizas globales habrán cambiado su distribución. La magnitud de tal desplazamiento se reflejará en un cambio promedio del 59% de la proporción de captura de poblaciones transfronterizas entre ZEEs vecinas para el 2030. Muchos países que dependen de la pesca para sustento económico y seguridad alimentaria emergen como zonas críticas de cambios transfronterizos. Estas zonas se caracterizan por cambios tempranos en la distribución de un número importante de poblaciones transfronterizas. Por lo tanto, los acuerdos pesqueros internacionales deben evaluarse por su capacidad para responder a los impactos socio-ecológicos del desplazamiento de poblaciones transfronterizas debido al cambio climático. Dichos acuerdos deberán de ser ajustados para limitar los posibles conflictos entre las partes de interés y evitar amenazar la sustentabilidad del recurso. Así mismo, los nuevos acuerdos que vayan a establecerse deberán considerar los posibles cambios en la distribución de poblaciones compartidas (y la incertidumbre asociada) para anticiparse a dichos conflictos y aumentar la resiliencia frente al cambio climático.Le changement climatique altère la distribution des stocks de poissons exploités posant de sérieux problèmes de juridiction et gestion des espèces partagées entre pays voisins, et/ou avec la haute mer. C’est en analysant l’échelle de temps de ces migrations transfrontalières que l’impact du changement climatique sur la gouvernance mondiale des pêches peut être évalué. Dans cette étude, nous explorons cette échelle de temps à l'aide d’un modèle de dynamique des populations marines exploitées couplé à des simulations dérivées d’un ensemble de modèles globaux océan-atmosphère. Les résultats montrent que d’ici 2030, pour le scénario à hautes émissions, 23% des stocks transfrontaliers auront changé de distribution et que 78% des zones économiques exclusives (ZEE) expérimenteront au moins une nouvelle espèce transfrontalière. A la fin du siècle, et pour ce même scénario, 81% des ZEE auront au moins une espèce transfrontalière et 45% des stocks transfrontaliers auront changé de distribution. La magnitude de tels changements de distribution est ici quantifiée par la variation dans la proportion de capture entre ZEE partageant ce stock transfrontalier. D’ici 2030, de tels changements entre ZEE seront de l’ordre de 59% à l'échelle globale, avec de nombreux pays dont la qualité de vie et la sécurité alimentaire dépendent de la pêche émergeant comme zones à haut risque. Ces zones se caractérisent par le déplacement précoce d’un grand nombre de stocks transfrontaliers. A la lumière de ces résultats, les traités et accords de pêche internationaux doivent être évalués pour leur capacité à répondre aux implications socio-écologiques du changement climatique et renégocier afin d’éviter tout conflit entre pays voisins. En anticipant des changements potentiels de distribution entre stocks transfrontaliers, tout nouvel accord de pêche se voudra plus résilient aux effets du changement climatique.As mudanças climáticas vêm promovendo alterações na distribuição dos estoques de peixes compartilhados por países vizinhos, tanto nas suas Zonas Econômicas Exclusivas (ZEE) como em águas oceânicas internacionais. A escala de tempo desse deslocamento transfronteiriço vai determinar como as mudanças climáticas afetarão o manejo pesqueiro internacional. Diante disso, o presente trabalho teve por objetivo analisar essa escala de tempo, combinando um amplo conjunto de simulações de um modelo do sistema terrestre sob um cenário de mudanças climáticas de altas emissões a um modelo de dinâmica populacional. Foi observado que, para 2030, 23% dos estoques transfronteiriços terão suas distribuições alteradas e 78% das ZEEs do mundo terão experimentado deslocamentos em pelo menos um estoque transfronteiriço. No final deste século, as projeções mostram que 45% dos estoques transfronteiriços do mundo sofrerão alterações e que 81% das ZEEs apresentarão alterações em pelo menos um estoque. A magnitude de tal deslocamento será refletida por uma mudança média de 59% na proporção de capturas de estoques transfronteiriços entre ZEEs vizinhas no ano de 2030. Muitos países que são altamente dependentes da pesca para subsistência e segurança alimentar surgem como pontos críticos para mudanças transfronteiriças. Estes são caracterizados por mudanças iniciais na distribuição de um número importante de estoques transfronteiriços. Os acordos internacionais de pesca precisam ser avaliados quanto à sua capacidade de abordar as implicações sócio-ecológicas de deslocamentos transfronteiriços impulsionados pelas mudanças climáticas e ajustados para limitar um possível conflito entre as partes de interesse. Da mesma forma, novos acordos devem considerar possíveis mudanças na distribuição de populações transfronteiriças a fim de antecipar tais conflitos e construir resiliência em face das mudanças climáticas e das incertezas que as acompanha.
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- 2022
46. Investigating Phytoplankton Manganese Limitation in the Southern Ocean with a Global Biogeochemical Model
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Nick Hawco, Alessandro Tagliabue, and Benjamin Twining
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- 2022
47. Examining seasonal variability in seawater iron isotopes from the Bermuda Atlantic Iron Time-series (BAIT)
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Eniko Toth, Matthias Sieber, Bettina Sohst, Daniela König, Alessandro Tagliabue, Peter Sedwick, Rene Boiteau, and Tim Conway
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- 2022
48. Diazotrophy as a key driver of the response of marine net primary productivity to climate change
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Léonard Dupont, Laurent Bopp, Roland Séférian, Corentin Clerc, Christian Ethé, Alessandro Tagliabue, Olivier Aumont, and Lester Kwiatkowski
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Earth system science ,Biomass (ecology) ,Biogeochemical cycle ,Climatology ,Global warming ,Climate change ,Primary production ,Environmental science ,Marine ecosystem ,Climate model - Abstract
The impact of anthropogenic climate change on marine net primary production (NPP) is a reason for concern because changing NPP will have widespread consequences for marine ecosystems and their associated services. Projections by the current generation of Earth System Models have suggested decreases in global NPP in response to future climate change, albeit with very large uncertainties. Here, we make use of two versions of the Institut Pierre Simon Laplace Climate Model (IPSL-CM) that simulate divergent NPP responses to similar high-emission scenarios in the 21st century and identify nitrogen fixation as the main driver of these divergent NPP responses. Differences in the way N-fixation is parameterized in the marine biogeochemical component PISCES of the IPSL-CMs lead to N-fixation rates that are either stable or double over the course of the 21st century, resulting in decreasing or increasing global NPP, respectively. An evaluation of these 2 model versions does not help constrain future NPP projection uncertainties. However, the use of a more comprehensive version of PISCES, with variable nitrogen-to-phosphorus ratios as well as a revised parameterization of the temperature sensitivity of N-fixation, suggests only moderate changes of global-averaged N-fixation in the 21st century. This leads to decreasing global NPP, in line with the model-mean changes of a recent multi-model intercomparison. Lastly, despite contrasting trends in NPP, all our model versions simulate similar and significant reductions in planktonic biomass. This suggests that projected plankton biomass may be a much more robust indicator than NPP of the potential impact of anthropogenic climate change on marine ecosystems across model.
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- 2021
49. Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services
- Author
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Momme Butenschön, Matthieu Lengaigne, Jérôme Vialard, William W. L. Cheung, Lester Kwiatkowski, Alessandro Tagliabue, Laurent Bopp, School of Environmental Sciences [Liverpool], University of Liverpool, Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centro Euro-Mediterraneo per i Cambiamenti Climatici [Bologna] (CMCC), Institute for the Oceans and Fisheries, University of British Columbia (UBC), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), and Océan et variabilité du climat (VARCLIM)
- Subjects
climate projections ,010504 meteorology & atmospheric sciences ,Climate change ,Carbon sequestration ,ocean net primary production ,01 natural sciences ,Ecosystem services ,03 medical and health sciences ,ocean modeling ,GE1-350 ,ocean biogeochemical model ,Ecosystem ,Marine ecosystem ,14. Life underwater ,oceanography ,ocean biogeochemical cycles ,030304 developmental biology ,0105 earth and related environmental sciences ,0303 health sciences ,Coupled model intercomparison project ,business.industry ,Environmental resource management ,Primary production ,15. Life on land ,Environmental sciences ,climate change ,13. Climate action ,[SDE]Environmental Sciences ,Environmental science ,Spatial variability ,earth system model (ESM) ,business - Abstract
Ocean net primary production (NPP) results from CO2 fixation by marine phytoplankton, catalysing the transfer of organic matter and energy to marine ecosystems, supporting most marine food webs, and fisheries production as well as stimulating ocean carbon sequestration. Thus, alterations to ocean NPP in response to climate change, as quantified by Earth system model experiments conducted as part of the 5th and 6th Coupled Model Intercomparison Project (CMIP5 and CMIP6) efforts, are expected to alter key ecosystem services. Despite reductions in inter-model variability since CMIP5, the ocean components of CMIP6 models disagree roughly 2-fold in the magnitude and spatial distribution of NPP in the contemporary era, due to incomplete understanding and insufficient observational constraints. Projections of NPP change in absolute terms show large uncertainty in CMIP6, most notably in the North Atlantic and the Indo-Pacific regions, with the latter explaining over two-thirds of the total inter-model uncertainty. While the Indo-Pacific has previously been identified as a hotspot for climate impacts on biodiversity and fisheries, the increased inter-model variability of NPP projections further exacerbates the uncertainties of climate risks on ocean-dependent human communities. Drivers of uncertainty in NPP changes at regional scales integrate different physical and biogeochemical factors that require more targeted mechanistic assessment in future studies. Globally, inter-model uncertainty in the projected changes in NPP has increased since CMIP5, which amplifies the challenges associated with the management of associated ecosystem services. Notably, this increased regional uncertainty in the projected NPP change in CMIP6 has occurred despite reduced uncertainty in the regional rates of NPP for historical period. Improved constraints on the magnitude of ocean NPP and the mechanistic drivers of its spatial variability would improve confidence in future changes. It is unlikely that the CMIP6 model ensemble samples the complete uncertainty in NPP, with the inclusion of additional mechanistic realism likely to widen projections further in the future, especially at regional scales. This has important consequences for assessing ecosystem impacts. Ultimately, we need an integrated mechanistic framework that considers how NPP and marine ecosystems respond to impacts of not only climate change, but also the additional non-climate drivers.
- Published
- 2021
50. Major processes of the dissolved cobalt cycle in the North and equatorial Pacific Ocean
- Author
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Rebecca Chmiel, Matthew R. McIlvin, Phoebe J. Lam, Mariko Hatta, Mak A. Saito, Alessandro Tagliabue, William J. Jenkins, Jessica N. Fitzsimmons, Allison Laubach, Nathan T. Lanning, and Jong-Mi Lee
- Subjects
Biogeochemical cycle ,geography ,geography.geographical_feature_category ,Mesopelagic zone ,Geotraces ,Seamount ,Oceanography ,Phytoplankton ,Environmental science ,Thermohaline circulation ,Transect ,Scavenging ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Abstract
Over the past decade, the GEOTRACES and wider trace metal geochemical community have made substantial contributions towards constraining the marine cobalt (Co) cycle and its major biogeochemical processes. However, few Co speciation studies have been conducted in the North and equatorial Pacific Ocean, a vast portion of the world’s oceans by volume and an important endmember of deep thermohaline circulation. Dissolved Co (dCo) samples, including total dissolved and labile Co, were measured at-sea during the GEOTRACES Pacific meridional transect (GP15) along the 152° W longitudinal from 56° N to 20° S. Along this transect, upper ocean dCo was linearly correlated to dissolved phosphate (slope = 82 ± 2 µM:M) due to phytoplankton uptake and remineralization. As depth increased, dCo concentrations became increasingly decoupled from phosphate concentrations due to co-scavenging with manganese oxide particles in the mesopelagic. The transect revealed an organically-bound coastal source of dCo to the Alaskan Stream associated with low salinity waters. An intermediate-depth hydrothermal flux of dCo was observed off the Hawaiian coast at the Loihi Seamount, and the elevated dCo was correlated to estimated xs3He at and above the vent site; however, the Loihi Seamount likely did not represent a major source of Co to the Pacific basin. Elevated concentrations of dCo within oxygen minimum zones (OMZs) in the equatorial North and South Pacific were consistent with the suppression of oxidative scavenging, and we estimate that future deoxygenation could increase the OMZ dCo inventory by 13–28 % over the next century. In North Pacific Deep Water (NPDW), a fraction of elevated ligand-bound dCo appeared protected from scavenging by the high biogenic particle flux in the North Pacific basin. This finding is counter to previous expectations of low dCo concentrations in the deep Pacific due to scavenging over thermohaline circulation. Compared to a Co global biogeochemical model, the observed transect displayed more extreme inventories and fluxes of dCo than predicted by the model, suggesting a highly dynamic Pacific Co cycle.
- Published
- 2021
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