A new OCB Activity is kicking off: Intercomparison of metatranscriptomic methods for characterizing microbial eukaryote contributions to the biological carbon pump
There are opportunities to speak and suggest speakers and themes in the bimonthly webinar series. And to participate in the intercomparison activities.
What balances oxygen removal in the equatorial Pacific? For a long time, oxygen in the eastern and central tropical Pacific was assumed to be mainly supplied by the large-scale advection of remotely ventilated waters via the equatorial current system and meridional circulation. A recent study used an eddy-resolving simulation of a global ocean model to show that turbulent mixing and its regulation by mesoscale eddies play a critical role in balancing oxygen removal (by consumption and upwelling) in the upper thermocline. Deeper in the water column, mean advection by the zonal currents and meridional circulation dominates. This mixing is tightly regulated by tropical instability waves, which intensify the shear between the equatorial currents and enhance the downward turbulent mixing flux of oxygen into the thermocline. Mesoscale phenomena thus play an indirect yet critical role as a local pathway of ventilation in this region. Testing these model-based hypotheses in the real ocean through dedicated field studies and long-term observations is needed to advance our understanding of the observed expansion of the oxygen deficient zones (ODZs) and model their future trajectory in a warmer and more stratified ocean.
Figure: The main processes that set the mean structure of oxygen in the equatorial Pacific are assessed in an eddy resolving simulation of the Community Earth System Model (CESM). Panel a shows the climatological oxygen distribution on the 26.25 isopycnal in CESM. Panels b-e show the contribution of advection by mean circulation and eddies, vertical mixing, and production and consumption. These processes are illustrated in panel f). Figure adapted from Eddebbar et al (2024).
Authors
Yassir A. Eddebbar (Scripps Institution of Oceanography)
Daniel B. Whitt (NASA Ames)
Ariane Verdy, (Scripps Institution of Oceanography)
Matthew R. Mazloff (Scripps Institution of Oceanography)
Aneesh C. Subramanian (CU Boulder)
Matthew C. Long, (National Center for Atmospheric Research)
Parasites are everywhere in the ocean. Including the microbial realm where a diverse, widespread group of protist parasites (Syndiniales) infect and kill a range of hosts, such as dinoflagellates, radiolarians, and even larger zooplankton. A complete Syndiniales infection cycle is only 2-3 days. First, the parasite is a free-living spore. Once inside a host, the parasite consumes the host’s carbon and becomes a larger multicellular organism (a trophont) eventually causing the host to burst open and release hundreds of new spores.
Like viruses, parasite lysis is expected to reroute organic carbon to the microbial loop, potentially decreasing the amount of carbon available for export to the deep sea. Yet, the role of Syndiniales in carbon cycling has been hard to define, as depth-specific infection dynamics and links to carbon export remain poorly understood.
Parasites are everywhere in the ocean. Including the microbial realm where a diverse, widespread group of protist parasites (Syndiniales) infect and kill a range of hosts, such as dinoflagellates, radiolarians, and even larger zooplankton. A complete Syndiniales infection cycle is only 2-3 days. First, the parasite is a free-living spore. Once inside a host, the parasite consumes the host’s carbon and becomes a larger multicellular organism (a trophont) eventually causing the host to burst open and release hundreds of new spores.
Like viruses, parasite lysis is expected to reroute organic carbon to the microbial loop, potentially decreasing the amount of carbon available for export to the deep sea. Yet, the role of Syndiniales in carbon cycling has been hard to define, as depth-specific infection dynamics and links to carbon export remain poorly understood.
Figure 1. The mean relative abundance of Syndiniales (purple) in the photic zone (<140 m) is negatively correlated with particulate organic carbon (POC) flux at 150 m (p-value < 0.001). Similar correlations are not significant (p-values > 0.05) for other major 18S taxonomic groups, like Dinophyceae (red) and Arthropoda (green).
In a recent study published in ISME Communications, authors analyzed an 18S rRNA gene metabarcoding dataset from the Bermuda Atlantic Time-series Study (BATS) site that included 4 years (2016-2019) and twelve depths (1-1000 m). Syndiniales were the most dominant 18S group at BATS, present throughout the photic and aphotic zones. These parasites were prominent in species networks constructed with 18S sequence data, with significant associations with dinoflagellates and copepods in the surface, and with radiolarians in the aphotic zone. In addition, Syndiniales were the only major 18S group to be significantly (and negatively) correlated to particulate carbon flux (at 150 m), which was estimated from sediment trap data collected concurrently at BATS (Figure 1). This is in situ evidence of flux attenuation among Syndiniales, as they recycle host carbon that would otherwise transfer up to larger organisms (e.g., via grazing). Lastly, authors found 19% of the Syndiniales community is linked between photic and aphotic zones, indicating that parasites are sinking on particles and/or are recirculated via diel vertical migration. Overall, these findings elevate the role of Syndiniales in microbial food webs and further emphasize the importance in quantifying parasite-host dynamics to inform ocean carbon models.
Authors
Sean Anderson (University of New Hampshire / Woods Hole Oceanographic Institution)
Leocadio Blanco-Bercial (Bermuda Institute of Ocean Sciences / Arizona State University)
Craig Carlson (University of California, Santa Barbara)
Elizabeth Harvey (University of New Hampshire)
Thank you for another inspiring OCB workshop! Recordings of the plenary sessions will be available in 1-2 months on the OCB YouTube Channel, and we will post an announcement here.
February 4: Gerrit Trapp-Müller, Fei Da, and Gabriella Akpah Yeboah
October 24: Robert Twilley and Marc Simard
September 26: Muriel Bruckner and Anastasia Pillouras
May 30: Bob Aller
April 18: Bin Zhao and Thomas Bianchi
March 14: Christophe Rabouille
River deltas and the adjacent coastal ocean are critical interfaces between terrestrial and oceanic environments. Deltas are the entry point of ~50% of the fresh water and 40% of all global particulate matter entering the ocean. They are major centers for particulate and dissolved organic carbon net transfer from land to ocean.
Recent evidence suggests that coastal oceans have become net sink for atmospheric CO2 during post-industrial times and continued human pressures in coastal zones and alterations to deltas will likely have an important impact on the future evolution of the coastal ocean’s carbon budget.
Despite the importance of deltas and blue carbon ecosystems to the global carbon cycle and coastal communities, land-to-ocean parameterizations in Earth System models are highly simplified and do not mechanistically include many of the processes involved in cycling carbon in these areas.
Significant and critical knowledge gaps on processes, their impacts on marine biogeochemistry, and the direction of future change exist—this workshop aims to address those knowledge gaps.
We will bring together scientists who are committed to exploring the physical, temporal, and biogeochemical processes that modulate fluxes of carbon to and from global deltas.
This scoping workshop will utilize momentum from the OCB 2023 Summer Workshop plenary session focused on deltaic systems to build a network of modelers, experimentalists, and field scientists working on deltas in this era of unprecedented climate change and other anthropogenic stresses, and will address and advance several OCB mission-specific topics:
Shaily Rahman (UC Boulder)
Kanchan Maiti (LSU)
Jaap Nienhuis (Utrecht University)
Cristina Schultz (Northeastern University)
Elizabeth Chamberlain (Wageningen University)
Julia Moriarty (CU Boulder)
Marisa Repasch (University of New Mexico)
WORKSHOP TOPICS
Ocean biogeochemistry – Influence of delta systems on adjacent coastal ocean in terms of carbon cycle (DIC/ALK/pCO2) both in water column and sediment, carbon burial and lateral transport of carbon.
Ecosystems – Role of salt marshes, mangroves, and sea grass on carbon retention and burial in delta plain and net export to adjacent ocean; reconstructions and forecasts of the distribution of these coastal ecosystems.
Novel methods and integration – Employing new technologies, e.g., chronology, remote sensing, to reconstruct and monitor delta change; integrating field and model data to study processes and change across timescales (past, present, and future).
Connectivity – Variability in hydrological connectivity across delta plain and delta shelf and its impact on carbon consumption, transport and retention.
Perturbations – Impact of climate and human driven changes including extreme events on delta carbon cycling.
Biogeochemical modeling: including mechanistic understanding of carbon cycling in the land-to-ocean continuum in global models, parameterizations of blue carbon ecosystems in high-resolution ocean models, quantifying organic and inorganic carbon transfers from deltas to theocean.
PRE-WORKSHOP
Objectives
Activities
OUTCOMES
The workshop aims to develop knowledge and define future research needs on the role of deltas in the global carbon cycle while building an interdisciplinary community around this understudied yet critical aspect of ocean biochemistry. To distribute these outcomes to the broader community there will be a consensus paper, a global delta carbon budget infographic, and an AGU Eos piece.
Role of deltaic sediments in regulating biogeochemical cycles (Chairs: Shaily Rahman, Jessica Luo, Cristina Schultz)
OCB2023 PLENARY SESSION TALKS (recorded June 2023)
Watch the informational webinar recording: https://www.youtube.com/watch?v=IXw9ZspNhP8
OCB will have a booth at the OSM24 exhibitor hall – come see us there during open hours. SSC members and Project Office staff will be at the booth to talk all things OCB and answer your questions about getting more involved.
Stay tuned for OCB-hosted sessions and town halls during OSM.
Given the broad and thriving mCDR landscape, the OCB SSC recently developed a Principles of Engagement document to help guide new research activities, collaborations, and communications around mCDR. Read the document HERE.
Carbon dioxide removal is an ineffective time machine
We are currently looking to identify diverse stakeholders in the Southeast who would like to connect with the Southeast regional node – find more information about the node below, and if interested please fill out this interest form and feel free to share widely.
We are currently looking to identify diverse stakeholders in California who would like to connect with the California Current regional node – please fill out this interest form.
Stanley, R, T Bell, Y Gao, C Gaston, D Ho, D Kieber, K Mackey, N Meskhidze, B Miller, H Potter, P Vlahos, P Yager, B Alexander, S Beaupre, S Craig, G Cutter, S Emerson, A Frossard, S Gasso, B Haus, W Keene, W Landing, R Moore, D Ortiz-Suslow, J Palter, F Paulot, E Saltzman, D Thornton, A Wozniak, L Zamora, H Benway. 2021. US SOLAS Science Report. 62pp. DOI 10.1575/1912/27821 Download the PDF
January 2023: OAIC-hosted SOLAS Seminar IV: The ABC’s of the sea surface microlayer: Aerosols, Bubbles, and Composition Watch the recording (for more related content see more SOLAS Seminars)
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Funding for the Ocean Carbon & Biogeochemistry Project Office is provided by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA). The OCB Project Office is housed at the Woods Hole Oceanographic Institution.
