Olivier Sulpis

Scopus Publications

Reassessment of the global distribution and diversity of modern planktonic foraminifera from the FORCIS database
Sonia Chaabane, Ralf Schiebel, Julie Meilland, Geert-Jan A. Brummer, P. Graham Mortyn, et al.
Journal of Micropalaeontology, 2026
Planktonic foraminifera (PF) shells are ubiquitous archives used as proxies in paleoceanography and play a crucial role in paleoclimate reconstructions. Species respond differently to abiotic and biotic factors and have shifted habitats with recent ocean warming. We re-evaluate the biogeographic limits of major PF species in the modern ocean, using the FORCIS data to extend the data coverage and explore potentially overlooked distributions of (small) species from the seminal works from the 1950s to the 1970s that were based on > 200 µm mesh-size plankton tows. We present a comprehensive update of their modern biogeography, vertical habitat distribution, and thermal tolerance using the FORCIS database, which includes all available water-column-sourced data from the last century. Our analysis confirms that the higher PF diversity is in the tropical and subtropical oceans. PF are observed in temperatures ranging from −2 to 31 °C, highlighting their remarkable thermal tolerance and/or adaptability to a wide range of temperatures. In addition, species that displayed a preferential habitat in lower latitudes in the 1950-to-1970 time interval (e.g. G. ruber) have been observed at higher latitudes over the last 50 years. Since the 1970s, medium-sized species have increased in abundance across all latitudes, from the tropical to polar oceans, a trend particularly evident in the extensive data from the eastern North Atlantic. The analysis of the FORCIS database updates the evolving biogeography of modern PF and advances our understanding of their ecology, providing revised benchmarks for paleoceanographic interpretations and the ecology of modern planktonic calcifiers.
RADIv2: an adaptable and versatile diagenetic model for coastal and open-ocean sediments
Hinne F. van der Zant, Olivier Sulpis, Jack J. Middelburg, Matthew P. Humphreys, Raphaël Savelli, et al.
Geoscientific Model Development, 2026
Ocean biogeochemistry is being altered by anthropogenic processes such as warming, acidification, eutrophication, and deoxygenation. Global-ocean biogeochemistry models are essential for investigating present and projecting future conditions, yet they often lack detailed representations of seafloor processes, despite the seafloor’s important role in material exchange between the biosphere and geosphere. To improve the representation of exchange across the sediment-water interface, we present RADIv2, a flexible and computationally efficient diagenetic model designed to simulate benthic biogeochemical processes across a range of marine environments, from coastal zones to abyssal plains. RADIv2 incorporates key features such as benthic methane cycling, a hydrodynamically controlled diffusive boundary layer thickness and porewater dispersion to the original RADI model, which enhance its ability to capture sediment-water exchange under varied environmental conditions. Using RADIv2, we develop and validate a regression-based metamodel that predicts benthic solute fluxes (oxygen, dissolved inorganic carbon, and alkalinity). This metamodel provides a universal and computationally efficient alternative to full-complexity coupled water column-sediment biogeochemical models at the global scale. Ultimately, this approach improves the representation of global biogeochemical cycles in ocean models by improving the parameterization of sediment-water exchange.
The contributions of various calcifying plankton to the South Atlantic calcium carbonate stock
Anne L. Kruijt, Robin van Dijk, Olivier Sulpis, Luc Beaufort, Guillaume Lassus, et al.
Biogeosciences, 2026
Pelagic calcifying plankton play an important role in the marine carbon cycle. However, field studies quantifying the contributions of multiple calcifying plankton groups to particulate inorganic carbon (PIC) stocks and export into the ocean interior are scarce. Most studies target one specific plankton group and adjust their sampling strategy accordingly, hampering comparisons. Furthermore, the literature is strongly biased towards foraminifera and coccolithophores, so aragonite contributions (e.g., gastropods) remain virtually unconstrained. A holistic view is required for future projections of marine carbon cycle changes. Here, we present the contributions of three main calcifying plankton groups – coccolithophores, foraminifera and planktonic gastropods (comprising heteropods and pteropods) – to PIC stocks and fluxes throughout the water column during a sampling campaign in the South Atlantic Ocean. Coccolithophore calcite dominated the depth-integrated PIC standing stock (∼ 80 %), followed by aragonite from planktonic gastropods (∼ 17 %) and calcite from foraminifera (∼ 3 %). The estimated production and export of the calcifying plankton largely depend on assumed turnover times and sinking speeds, which both have large uncertainties. Coccolithophores contributed 92 %–99 % of the produced PIC, depending on planktonic gastropod turnover time, and from 52 % to 99 % of the exported PIC, depending on their mode of sinking. Both the standing stock and export of planktonic gastropods was significantly larger than that of foraminifera. Similarity between our results and those from different ocean basins suggests that these patterns are global in nature, implying that not only coccolithophores but also gastropods may be a more important contributor to the oceans PIC inventory than foraminifera, challenging a longstanding paradigm.
Elucidating the Role of Marine Benthic Carbon in a Changing World
Cristina Schultz, Jessica Y. Luo, Damian C. Brady, Robinson W. Fulweiler, Matthew H. Long, et al.
Global Biogeochemical Cycles, 2025
The ocean plays a major role in controlling atmospheric carbon at decadal to millennial timescales, with benthic carbon representing the only geologic‐scale storage of oceanic carbon. Despite its importance, detailed benthic ocean observations are limited and representation of the benthic carbon cycle in ocean and Earth system models (ESMs) is mostly empirical with little prognostic capacity, which hinders our ability to properly understand the long‐term evolution of the carbon cycle and climate change‐related feedbacks. The Benthic Ecosystem and Carbon Synthesis (BECS) working group, with the support of the US Ocean Carbon & Biogeochemistry Program (OCB), identified key challenges limiting our understanding of benthic systems, opportunities to act on these challenges, and pathways to increase the representation of these systems in global modeling and observational efforts. We propose a set of priorities to advance mechanistic understanding and better quantify the importance of the benthos: (a) implementing a model intercomparison exercise with existing benthic models to support future model development, (b) data synthesis to inform both model parameterizations and future observations, (c) increased deployment of platforms and technologies in support of in situ benthic monitoring (e.g., from benchtop to field mesocosm), and (d) global coordination of a benthic observing program (“GEOSed”) to fill large regional data gaps and evaluate the mechanistic understanding of benthic processes acquired throughout the previous steps. Addressing these priorities will help inform solutions to both global and regional resource management and climate adaptation strategies.
Migrating is not enough for modern planktonic foraminifera in a changing ocean
Sonia Chaabane, Thibault de Garidel-Thoron, Julie Meilland, Olivier Sulpis, Thomas B. Chalk, et al.
Nature, 2024
Rising carbon dioxide emissions are provoking ocean warming and acidification1,2, altering plankton habitats and threatening calcifying organisms3, such as the planktonic foraminifera (PF). Whether the PF can cope with these unprecedented rates of environmental change, through lateral migrations and vertical displacements, is unresolved. Here we show, using data collected over the course of a century as FORCIS4 global census counts, that the PF are displaying evident poleward migratory behaviours, increasing their diversity at mid- to high latitudes and, for some species, descending in the water column. Overall foraminiferal abundances have decreased by 24.2 ± 0.1% over the past eight decades. Beyond lateral migrations5, our study has uncovered intricate vertical migration patterns among foraminiferal species, presenting a nuanced understanding of their adaptive strategies. In the temperature and calcite saturation states projected for 2050 and 2100, low-latitude foraminiferal species will face physicochemical environments that surpass their current ecological tolerances. These species may replace higher-latitude species through poleward shifts, which would reduce low-latitude foraminiferal diversity. Our insights into the adaptation of foraminifera during the Anthropocene suggest that migration will not be enough to ensure survival. This underscores the urgent need for us to understand how the interplay of climate change, ocean acidification and other stressors will impact the survivability of large parts of the marine realm.
Size normalizing planktonic Foraminifera abundance in the water column
Sonia Chaabane, Thibault de Garidel‐Thoron, Xavier Giraud, Julie Meilland, Geert‐Jan A. Brummer, et al.
Limnology and Oceanography Methods, 2024
Planktonic Foraminifera have been collected from the water column with different plankton sampling devices equipped with nets of various mesh sizes, which impedes direct comparison of observed quantifications. Here, we use data on the community size structure of planktonic Foraminifera to assess the impact of mesh size on the measured abundance (ind m−3) of planktonic Foraminifera. We use data from the FORCIS database (Chaabane et al., 2023, Scientific Data 10: 354) on the global ocean at different sampling depths over the past century. We find a global cumulative increase in abundance with size, which is best described using a Michaelis–Menten function. This function yields multiplication factors by which one size fraction can be normalized to any other size fraction equal to or larger than 100 μm. The resulting size normalization model is calibrated over a range of different depth intervals, and validated with an independent dataset from various depth ranges. The comparison to Berger's (1969, Deep. Res. Oceanogr. Abstr. 16: 1–24) equivalent catch approach shows a significant increase in the predictive skill of the model. The new size normalization scheme enables comparison of Foraminifera abundance data sampled with plankton nets of different mesh sizes, such as compiled in the FORCIS database. The correction methodology may be effectively employed for various other plankton groups such as diatoms and dinoflagellates.
Synthesis of In Situ Marine Calcium Carbonate Dissolution Kinetic Measurements in the Water Column
Ben A. Cala, Olivier Sulpis, Mariette Wolthers, Matthew P. Humphreys
Global Biogeochemical Cycles, 2024
Calcium carbonate (CaCO3) dissolution is an integral part of the ocean's carbon cycle. However, laboratory measurements and ocean alkalinity budgets disagree on the rate and loci of dissolution. In situ dissolution studies can help to bridge this gap, but so far published studies have not been utilized as a whole because they have not previously been compiled into one data set and lack carbonate system data to compare between studies. Here, we compile all published measurements of CaCO3 dissolution rates in the water column (11 studies, 752 data points). Combining World Ocean Atlas data (temperature, salinity) with the neural network CANYON‐B (carbonate system variables), we estimate seawater saturation state (Ω) for each rate measurement. We find that dissolution rates at the same Ω vary by 2 orders of magnitude. Using a machine learning approach, we show that while Ω is the main driver of dissolution rate, most variability can be attributed to differences in experimental design, above all bias due to (diffusive) transport and the synthetic or biogenic nature of CaCO3. The compiled data set supports previous findings of a change in the mechanism driving dissolution at Ωcrit = 0.8 that separates two distinct dissolution regimes: rslow = 0.29 · (1 − Ω)0.68(±0.16) mass% day−1 and rfast = 2.95 · (1 − Ω)2.2(±0.2) mass% day−1. Above the saturation horizon, one study shows significant dissolution that cannot solely be explained by established theories such as zooplankton grazing and organic matter degradation. This suggests that other, non‐biological factors may play a role in shallow dissolution.
The Changing Biological Carbon Pump of the South Atlantic Ocean
L. Delaigue, O. Sulpis, G.‐J. Reichart, M. P. Humphreys
Global Biogeochemical Cycles, 2024
Global marine anthropogenic CO2 inventories have traditionally emphasized the North Atlantic's role in the carbon cycle, while Southern hemisphere processes are less understood. The South Subtropical Convergence (SSTC) in the South Atlantic, a juncture of distinct nutrient‐rich waters, offers a valuable study area for discerning the potential impacts of climate change on the ocean's biological carbon pump (Csoft). Using discrete observations from GLODAPv2.2022 and BGC‐Argo at 40°S in the Atlantic Ocean from 1972 to 2023, an increase in dissolved inorganic carbon (DIC) of +1.44 ± 0.11 μmol kg−1 yr−1 in surface waters was observed. While anthropogenic CO2 played a role, variations in the contribution of Csoft were observed. Discrepancies emerged in assessing Csoft based on the tracers employed: when using AOU, Csoft(AOU) recorded an increase of +0.20 ± 0.03 μmol kg−1 yr−1, while using nitrate as the reference, Csoft(NO3) displayed an increase of +0.85 ± 0.07 μmol kg−1 yr−1. Key processes such as water mass composition shifts, changes in oxygenation, remineralization in the Southern Ocean, and the challenges they pose in accurately representing the evolving Csoft are discussed. These findings highlight that while global studies primarily attribute DIC increase to anthropogenic CO2, observations at 40°S reveal an intensified biological carbon pump, showing that regional DIC changes are more complex than previously thought and emphasizing the need for better parameterizations to compute the BCP in the marine carbon budget.
Laboratory Observation of the Buffering Effect of Aragonite Dissolution at the Seafloor
H. van de Mortel, L. Delaigue, M. P. Humphreys, J. J. Middelburg, S. Ossebaar, et al.
Journal of Geophysical Research Biogeosciences, 2024
Carbon dioxide entering and acidifying the ocean can be neutralized by the dissolution of calcium carbonate, which is mainly found in two mineral forms. Calcite is the more stable form and is often found in deep‐sea sediments, whilst aragonite is more soluble and therefore rarely preserved. Recent research shows aragonite may account for a much larger portion of marine calcium carbonate export to the ocean interior via the biological pump than previously thought, and that aragonite does reach the deep sea and seafloor despite rarely being buried. If aragonite is present and dissolving at the seafloor it will raise local pH and calcium and carbonate concentrations, potentially enough to inhibit calcite dissolution, representing a deep‐sea, carbonate version of galvanization. Here, we test this hypothesis by simulating aragonite dissolution at the sediment‐water interface in the laboratory and measuring its effects on pH using microsensors. We show that the addition of aragonite to calcite sediment, overlain by seawater undersaturated with respect to both minerals, results in an unchanged alkalinity flux out of the dissolving sediment, suggesting a decrease the net dissolution rate of calcite. In combination with a diagenetic model, we show that aragonite dissolution can suppress calcite dissolution in the top millimeters of the seabed, locally leading to calcite precipitation within 1 day. Future research efforts should quantify this galvanization effect in situ, as this process may represent an important component of the marine carbon cycle, assigning a key role to aragonite producers in controlling ocean alkalinity and preserving climatic archives.
Future directions for deep ocean climate science and evidence-based decision making
Helen R. Pillar, Elizabeth Hetherington, Lisa A. Levin, Laura Cimoli, Jonathan M. Lauderdale, et al.
Frontiers in Climate, 2024
IntroductionA defining aspect of the Intergovernmental Panel on Climate Change (IPCC) assessment reports (AR) is a formal uncertainty language framework that emphasizes higher certainty issues across the reports, especially in the executive summaries and short summaries for policymakers. As a result, potentially significant risks involving understudied components of the climate system are shielded from view.MethodsHere we seek to address this in the latest, sixth assessment report (AR6) for one such component—the deep ocean—by summarizing major uncertainties (based on discussions of low confidence issues or gaps) regarding its role in our changing climate system. The goal is to identify key research priorities to improve IPCC confidence levels in deep ocean systems and facilitate the dissemination of IPCC results regarding potentially high impact deep ocean processes to decision-makers. This will accelerate improvement of global climate projections and aid in informing efforts to mitigate climate change impacts. An analysis of 3,000 pages across the six selected AR6 reports revealed 219 major science gaps related to the deep ocean. These were categorized by climate stressor and nature of impacts.ResultsHalf of these are biological science gaps, primarily surrounding our understanding of changes in ocean ecosystems, fisheries, and primary productivity. The remaining science gaps are related to uncertainties in the physical (32%) and biogeochemical (15%) ocean states and processes. Model deficiencies are the leading cited cause of low certainty in the physical ocean and ice states, whereas causes of biological uncertainties are most often attributed to limited studies and observations or conflicting results.DiscussionKey areas for coordinated effort within the deep ocean observing and modeling community have emerged, which will improve confidence in the deep ocean state and its ongoing changes for the next assessment report. This list of key “known unknowns” includes meridional overturning circulation, ocean deoxygenation and acidification, primary production, food supply and the ocean carbon cycle, climate change impacts on ocean ecosystems and fisheries, and ocean-based climate interventions. From these findings, we offer recommendations for AR7 to avoid omitting low confidence-high risk changes in the climate system.
Inorganic blue carbon sequestration
Olivier Sulpis, Jack J. Middelburg
Nature Sustainability, 2023
Respiration Patterns in the Dark Ocean
Olivier Sulpis, David S. Trossman, Mark Holzer, Emil Jeansson, Siv K. Lauvset, et al.
Global Biogeochemical Cycles, 2023
Aragonite dissolution protects calcite at the seafloor
Olivier Sulpis, Priyanka Agrawal, Mariette Wolthers, Guy Munhoven, Matthew Walker, et al.
Nature Communications, 2022
RADIv1: a non-steady-state early diagenetic model for ocean sediments in Julia and MATLAB/GNU Octave
Olivier Sulpis, Matthew P. Humphreys, Monica M. Wilhelmus, Dustin Carroll, William M. Berelson, et al.
Geoscientific Model Development, 2022
Calcium carbonate dissolution patterns in the ocean
Olivier Sulpis, Emil Jeansson, Ashley Dinauer, Siv K. Lauvset, Jack J. Middelburg
Nature Geoscience, 2021
Current estimates of K1∗and K2∗appear inconsistent with measured CO2 system parameters in cold oceanic regions
Olivier Sulpis, Siv K. Lauvset, Mathilde Hagens
Ocean Science, 2020
Control of CaCO3 dissolution at the deep seafloor and its consequences
Bernard P. Boudreau, Olivier Sulpis, Alfonso Mucci
Geochimica Et Cosmochimica Acta, 2020
Reduced CaCO3 Flux to the Seafloor and Weaker Bottom Current Speeds Curtail Benthic CaCO3 Dissolution Over the 21st Century
Olivier Sulpis, Carolina O. Dufour, David S. Trossman, Andrea J. Fassbender, Brian K. Arbic, et al.
Global Biogeochemical Cycles, 2019
Controlling the diffusive boundary layer thickness above the sediment–water interface in a thermostated rotating-disk reactor
Olivier Sulpis, Alfonso Mucci, Bernard P. Boudreau, Mark A. Barry, Bruce D. Johnson
Limnology and Oceanography Methods, 2019
Current CaCO3 dissolution at the seafloor caused by anthropogenic CO2
Olivier Sulpis, Bernard P. Boudreau, Alfonso Mucci, Chris Jenkins, David S. Trossman, et al.
Proceedings of the National Academy of Sciences of the United States of America, 2018
Calcite dissolution kinetics at the sediment-water interface in natural seawater
Olivier Sulpis, Claire Lix, Alfonso Mucci, Bernard P. Boudreau
Marine Chemistry, 2017

Olivier Sulpis

RESEARCH, TEACHING, or OTHER INTERESTS

Scopus Publications

RECENT SCHOLAR PUBLICATIONS

MOST CITED SCHOLAR PUBLICATIONS