Ocean Carbon & Biogeochemistry
Studying marine ecosystems and biogeochemical cycles in the face of environmental change
  • Home
  • About OCB
    • About Us
    • Scientific Breadth
      • Biological Pump
      • Changing Marine Ecosystems
      • Changing Ocean Chemistry
      • Estuarine and Coastal Carbon Fluxes
      • Ocean Carbon Uptake and Storage
      • Ocean Observatories
    • Code of Conduct
    • Get Involved
    • Project Office
    • Scientific Steering Committee
    • OCB committees
      • Ocean Time-series
      • US Biogeochemical-Argo
      • Ocean-Atmosphere Interaction
  • Activities
    • Summer Workshop
    • OCB Webinars
    • Guidelines for OCB Workshops & Activities
    • Topical Workshops
      • CMIP6 Models Workshop
      • Coastal BGS Obs with Fisheries
      • C-saw extreme events workshop
      • Expansion of BGC-Argo and Profiling Floats
      • Fish, fisheries and carbon
      • Future BioGeoSCAPES program
      • GO-BCG Scoping Workshop
      • Lateral Carbon Flux in Tidal Wetlands
      • Leaky Deltas Workshop – Spring 2025
      • Marine CDR Workshop
      • Ocean Nucleic Acids ‘Omics
      • Pathways Connecting Climate Changes to the Deep Ocean
    • Small Group Activities
      • Aquatic Continuum OCB-NACP Focus Group
      • Arctic-COLORS Data Synthesis
      • BECS Benthic Ecosystem and Carbon Synthesis WG
      • Carbon Isotopes in the Ocean Workshop
      • CMIP6 WG
      • Filling the gaps air–sea carbon fluxes WG
      • Fish Carbon WG
      • Meta-eukomics WG
      • mCDR
      • Metaproteomic Intercomparison
      • Mixotrophs & Mixotrophy WG
      • N-Fixation WG
      • Ocean Carbonate System Intercomparison Forum
      • Ocean Carbon Uptake WG
      • OOI BGC sensor WG
      • Operational Phytoplankton Observations WG
      • Phytoplankton Taxonomy WG
    • Other Workshops
    • Science Planning
      • Coastal CARbon Synthesis (CCARS)
      • North Atlantic-Arctic
    • Ocean Acidification PI Meetings
    • Training Activities
      • PACE Hackweek 2025
      • PACE Hackweek 2024
      • PACE Training Activity 2022
  • Science Support
    • Data management and archival
    • Early Career
    • Funding Sources
    • Jobs & Postdocs
    • Meeting List
    • OCB Topical Websites
      • Ocean Fertilization
      • Trace gases
      • US IIOE-2
    • Outreach & Education
    • Promoting your science
    • Student Opportunities
    • OCB Activity Proposal Solicitations
      • Guidelines for OCB Workshops & Activities
    • Travel Support
  • Publications
    • OCB Workshop Reports
    • Science Planning and Policy
    • Newsletter Archive
  • Science Highlights
  • News

Archive for anthropogenic carbon

A suite of CO2 removal approaches modeled for the 1.5 ˚C future

Posted by mmaheigan 
· Thursday, August 31st, 2023 

Carbon dioxide removal (CDR) is “unavoidable” in efforts to limit end-of-century warming to below 1.5 °C. This is because some greenhouse gas emissions sources—non-CO2 from agriculture, and CO2 from shipping, aviation, and industrial processes—will be difficult to avoid, requiring CDR to offset their climate impacts. Policymakers are interested in a wide variety of ways to draw down CO2 from the atmosphere, but to date, the modeling scenarios that inform international climate policies have mostly used biomass energy with carbon capture and storage (BECCS) as a proxy for all CDR. It is critical to understand the potential of a full suite of CDR technologies, to understand their interactions with energy-water-land systems and to begin preparing for these impacts.

Figure caption: Each of the six carbon dioxide removal approaches identified in recent U.S. legislation and modeled for this study could bring unique benefits and tradeoffs to the energy-water-land system. This image depicts afforestation, direct ocean capture, direct air capture, biochar, enhanced weathering, and bioenergy with carbon capture and storage in clockwise order. Floating carbon dioxide molecules hover above the landscape (image credit: Nathan Johnson, PNNL).

A recent study published in the journal Nature Climate Change was the first to model six major CDR pathways in an integrated assessment model. The modeled pathways range from bioenergy with carbon storage and afforestation (already represented by most models), also direct air capture, biochar and crushed basalt spreading on global croplands, and electrochemical stripping of CO2 from seawater aka direct ocean capture. The removal potential contributed by each of the six pathways varies widely across different regions of the world. Direct ocean capture showed the smallest removal potential but has important potential synergies with water desalination. This method could help arid regions such as the Middle East meet their water needs in a warming world. Enhanced weathering has much larger (GtCO2-yr-1) removal potential and could potentially help ameliorate ocean acidification. Overall, similar total amounts of CO2 are removed compared to other modeling scenarios, but broader set of technologies lessens the risk that any one of them would become politically or environmentally untenable.

Authors:
Jay Fuhrman  (Joint Global Change Research Institute)
Candelaria Bergero (Joint Global Change Research Institute)
Maridee Weber (Joint Global Change Research Institute)
Seth Monteith (ClimateWorks Foundation)
Frances M. Wang (ClimateWorks Foundation)
Andres F. Clarens (University of Virginia)
Scott C. Doney (University of Virginia)
William Shobe (University of Virginia)
Haewon McJeon (Joint Global Change Research Institute )

Twitter: @pnnlab @climateworks @uva

Adaptive emission pathways to stabilize global temperatures

Posted by mmaheigan 
· Thursday, May 11th, 2023 

Around the world, countries have agreed in the Paris Agreement to limit global warming well below 2°C and to pursue efforts to reduce global warming to 1.5°C. However, large uncertainties remain about which emission pathways will allow us to reach this goal. A recent paper presents a new adaptive approach to create emission pathways and estimate the necessary emission reductions every five years, following the stocktake process of the Paris Agreement. This Adaptive Emissions Reduction Approach (AERA) is solely based on past warming rates, and emissions of CO2 and non-CO2 radiative agents, and explicitly does not rely on projections by Earth System Models. Updating the emission pathways every five years, circumvents uncertainties in the climate system and its transient response to cumulative emissions (TCRE). Testing with the Bern3D-LPX Earth System Model of Intermediate Complexity shows that the approach works robustly across a wide range of TCREs, avoids large overshoots, and only small changes to the emission pathways are necessary every five years. This approach will allow policymakers to estimate emission pathways and create a base for international negotiations. Furthermore, it allows simulations with Earth System Models that all converge to the same temperature target to compare the climate at stabilized warming levels.

Figure caption: The three steps of the Adaptive Emission Reduction Approach: 1) Estimating the past anthropogenic warming, 2) estimating the remaining emission budget, and 3) redistributing it over the future years.

 

Authors
Jens Terhaar (University of Bern, now Woods Hole Oceanographic Institution)
Thomas L Frölicher (University of Bern)
Mathias T Aschwanden (University of Bern)
Pierre Friedlingstein (University of Exeter, Ecole Normale Superieure)
Fortunat Joos (University of Bern)

 

Twitter @JensTerhaar @froeltho @PFriedling @unibern @snsf_ch @4C_H2020 @ExeterUniMaths @Geosciences_ENS @IPSL_outreach

What drives decadal changes in the Chesapeake Bay carbonate system?

Posted by mmaheigan 
· Tuesday, May 3rd, 2022 

Understanding decadal changes in the coastal carbonate system (CO2-system) is essential for predicting how the health of these waters is affected by anthropogenic drivers, such as changing atmospheric conditions and terrestrial inputs. However, studies that quantify the relative impacts of these drivers are lacking.

A recent study in Journal of Geophysical Research: Oceans identified the primary drivers of acidification in the Chesapeake Bay over the past three decades. The authors used a three-dimensional hydrodynamic-biogeochemistry model to quantify the relative impacts on the Bay CO2-system from increases in atmospheric CO2, temperature, oceanic dissolved inorganic carbon (DIC) concentrations, terrestrial loadings of total alkalinity (TA) and DIC, as well as decreases in terrestrial nutrient inputs. Decadal changes in the surface CO2-system in the Chesapeake Bay exhibit large spatial and seasonal variability due to the combination of influences from the land, ocean and atmosphere. In the upper Bay, increased riverine TA and DIC from the Susquehanna River have increased surface pH, with other drivers only contributing to decadal changes that are one to two orders of magnitude smaller. In the mid- and lower Bay, higher atmospheric CO2 concentrations and reduced nutrient loading are the two most critical drivers and have nearly equally reduced surface pH in the summer. These decadal changes in surface pH show significant seasonal variability with the greatest magnitude generally aligning with the spring and summer shellfish production season (Figure 1).

Figure 1: Overall changes in modeled surface pH (ΔpHall) due to all global and terrestrial drivers combined over the past 30 years (i.e., 2015–2019 relative to 1985–1989). ΔpHall includes changes in surface pH due to increased atmospheric CO2, increased atmospheric thermal forcing, increased oceanic dissolved inorganic carbon concentrations, decreased riverine nitrate concentrations, decreased riverine organic nitrogen concentrations, and increased riverine total alkalinity and dissolved inorganic carbon concentrations.

 

These results indicate that a number of global and terrestrial drivers play crucial roles in coastal acidification. The combined effects of the examined drivers suggest that calcifying organisms in coastal surface waters are likely facing faster decreasing rates of pH than those in open ocean ecosystems. Decreases in surface pH associated with nutrient reductions highlight that the Chesapeake Bay ecosystem is returning to a more natural condition, e.g., a condition when anthropogenic nutrient input from the watershed was lower. However, increased atmospheric CO2 is simultaneously accelerating the rate of change in pH, exerting increased stress on estuarine calcifying organisms. For ecosystems such as the Chesapeake Bay where nutrient loading is already being managed, controlling the emissions of anthropogenic CO2 globally becomes increasingly important to decelerate the rate of acidification and to relieve the stress on estuarine calcifying organisms. Future observational and modeling studies are needed to further investigate how the decadal trends in the Chesapeake Bay CO2-system may vary with depth. These efforts will improve our current understanding of long-term change in coastal carbonate systems and their impacts on the shellfish industry.

 

Authors:
Fei Da (Virginia Institute of Marine Science, William & Mary, USA)
Marjorie A. M. Friedrichs (Virginia Institute of Marine Science, William & Mary, USA)
Pierre St-Laurent (Virginia Institute of Marine Science, William & Mary, USA)
Elizabeth H. Shadwick (CSIRO Oceans and Atmosphere, Australia)
Raymond G. Najjar (The Pennsylvania State University, USA)
Kyle E. Hinson (Virginia Institute of Marine Science, William & Mary, USA)

The ephemeral and elusive COVID blip in ocean carbon

Posted by mmaheigan 
· Monday, September 20th, 2021 

The global pandemic of the last nearly two years has affected all of us on a daily and long-term basis. Our planet is not exempt from these impacts. Can we see a signal of COVID-related CO2 emissions reductions in the ocean? In a recent study, Lovenduski et al. apply detection and attribution analysis to output from an ensemble of COVID-like simulations of an Earth system model to answer this question. While it is nearly impossible to detect a COVID-related change in ocean pH, the model produces a unique fingerprint in air-sea DpCO2 that is attributable to COVID. Challengingly, the large interannual variability in the climate system  makes this fingerprint  difficult to detect at open ocean buoy sites.

This study highlights the challenges associated with detecting statistically meaningful changes in ocean carbon and acidity following CO2 emissions reductions, and reminds the reader that it may be difficult to observe intentional emissions reductions — such as those that we may enact to meet the Paris Climate Agreement – in the ocean carbon system.

Figure caption: The fingerprint (pink line) of COVID-related CO2 emissions reductions in global-mean surface ocean pH and air-sea DpCO2, as estimated by an ensemble of COVID-like simulations in an Earth system model.   While the pH fingerprint is not particularly exciting, the air-sea DpCO2 fingerprint displays a temporary weakening of the ocean carbon sink in 2021 due to COVID emissions reductions.

 

Authors:
Nikki Lovenduski (University of Colorado Boulder)
Neil Swart (Canadian Centre for Climate Modeling and Analysis)
Adrienne Sutton (NOAA Pacific Marine Environmental Laboratory)
John Fyfe (Canadian Centre for Climate Modeling and Analysis)
Galen McKinley (Columbia University and Lamont Doherty Earth Observatory)
Chris Sabine (University of Hawai’i at Manoa)
Nancy Williams (University of South Florida)

How atmospheric and oceanographic forcing impact the carbon sequestration in an ultra-oligotrophic marine system

Posted by mmaheigan 
· Wednesday, August 11th, 2021 

Sinking particles are a critical conduit for the export of material from the surface to the deep ocean. Despite their importance in oceanic carbon cycling, little is known about the composition and seasonal variability of sinking particles which reach abyssal depths. Oligotrophic waters cover ~75% of the ocean surface and contribute over 30% of the global marine carbon fixation. Understanding the processes that control carbon export to the deep oligotrophic areas is crucial to better characterize the strength and efficiency of the biological pump as well as to project the response of these systems to climate fluctuations and anthropogenic perturbations.

In a recent study published in Frontiers in Earth Science, authors synthesized data from atmospheric and oceanographic parameters, together with main mass components, and stable isotope and source-specific lipid biomarker composition of sinking particles collected in the deep Eastern Mediterranean Sea (4285m, Ierapetra Basin) for a three-year period (June 2010-June 2013). In addition, this study compared the sinking particulate flux data with previously reported deep-sea surface sediments from the study area to shed light on the benthic–pelagic coupling.

Figure Caption: a) Biplot of net primary productivity vs export efficiency (top and bottom horizontal dashed lines indicate threshold for high and low export efficiency regimes). b) Biplot of POC-normalized concentrations of terrestrial vs. phytoplankton-derived lipid biomarkers of the sinking particles collected in the deep Eastern Mediterranean Sea (Ierapetra Basin, NW Levantine Basin) from June 2010–June 2013, and surface sediments collected from January 2007 to June 2012 in the study area.

Both seasonal and episodic pulses are crucial for POC export to the deep Eastern Mediterranean Sea. POC fluxes peaked in spring April–May 2012 (12.2 mg m−2 d−1) related with extreme atmospheric forcing. Overall, summer particle export fuels more efficient carbon sequestration than the other seasons. The results of this study highlight that the combination of extreme weather events and aerosol deposition can trigger an influx of both marine labile carbon and anthropogenic compounds to the deep. Finally, the comparison of the sinking particles flux data with surface sediments revealed an isotopic discrimination, as well as a preferential degradation of labile organic matter during deposition and burial, along with higher preservation of land-derived POC in the underlying sediments. This study provides key knowledge to better understand the export, fate and preservation vs. degradation of organic carbon, and for modeling the organic carbon burial rates in the Mediterranean Sea.

 

Authors:
Rut Pedrosa-Pamies (The Ecosystems Center, Marine Biological Laboratory, US; Research Group in Marine Geosciences, University of Barcelona, Spain)
Constantine Parinos (Institute of Oceanography, Hellenic Centre for Marine Research, Greece)
Anna Sanchez-Vidal (Group in Marine Geosciences, University of Barcelona, Spain)
Antoni Calafat (Group in Marine Geosciences, University of Barcelona, Spain)
Miquel Canals (Group in Marine Geosciences, University of Barcelona, Spain)
Dimitris Velaoras (Institute of Oceanography, Hellenic Centre for Marine Research, Greece)
Nikolaos Mihalopoulos (Environmental Chemical Processes Laboratory, University of Crete; National Observatory of Athens, Greece)
Maria Kanakidou (Environmental Chemical Processes Laboratory, University of Crete Greece)
Nikolaos Lampadariou (Institute of Oceanography, Hellenic Centre for Marine Research, Greece)
Alexandra Gogou (Institute of Oceanography, Hellenic Centre for Marine Research, Greece)

Air-sea gas disequilibrium drove deoxygenation of the deep ice-age ocean

Posted by mmaheigan 
· Thursday, March 18th, 2021 

During the Last Glacial Maximum (~20,000 years ago, LGM) sediment data show that the deep ocean had lower dissolved oxygen (O2) concentrations than the preindustrial ocean, despite cooler temperatures of this period increasing O2 solubility in sea water.

Figure 1. a) Whole ocean inventory of the O2 components in the preindustrial control (PIC): total O2 (O2); the preformed components equilibrium O2 (O2 equilibrium), physical disequilibrium O2 (O2 diseq phys) and biologically-mediated disequilibrium (O2 diseq bio); and O2 respired from soft-tissue (O2 soft). b) The difference in whole ocean inventory of O2 components between the LGM and PIC simulations.

In a study published in Nature Geoscience, the authors provide one of the first explanations for glacial deoxygenation. The authors combined a data-constrained model of the preindustrial (PIC) and LGM ocean with a novel decomposition of O2 to assess the processes affecting the oceanic distribution of oxygen. The decomposition allowed for the preformed disequilibrium O2—the amount of oxygen that deviates from its solubility equilibrium value when at the surface—to be tracked, along with other contributions such as the O2 consumed by bacterial respiration of organic matter. In the preindustrial ocean, a third of the subsurface oxygen deficit was a result of disequilibrium rather than oxygen consumed by bacteria. This contradicts previous assumptions (Figure 1a). Nearly 80% of the disequilibrium resulted from upwelling waters, depleted in O2 due to respiration, not fully equilibrating before re-subduction into the ocean interior. This effect was even greater during the LGM (Figure 1b). The authors attributed this largely to the widespread presence of sea ice—which acts as a cap on the surface preventing the water from gaining oxygen from the atmosphere—in the ocean around Antarctica, with a smaller contribution from iron fertilization.

This study provides one of the first mechanistic explanations for LGM deep ocean deoxygenation. As the ocean is currently losing oxygen due to warming, the effect of other processes, including sea ice changes, could prove important for understanding long-term ocean oxygenation changes.

Authors
Ellen Cliff (University of Oxford)
Samar Khatiwala (University of Oxford)
Andreas Schmittner (Oregon State University)

Joint highlight with GEOTRACES International Project Office

Wildfire impacts on coastal ocean phytoplankton

Posted by mmaheigan 
· Wednesday, February 24th, 2021 

Wildfire frequency, size, and destructiveness has increased over the last two decades, particularly in coastal regions such as Australia, Brazil, and the western United States. While the impact of fire on land, plants, and people is well documented, very few studies have been able to evaluate the impact of fires on ocean ecosystems. A serendipitously planned research cruise one week after the Thomas Fire broke out in California in December 2017 allowed the authors of this study and their colleagues to sample the adjacent Santa Barbara Channel during this devastating extreme fire event.

In a recent paper published in Journal of Geophysical Research: Oceans, the authors describe the phytoplankton community in the Santa Barbara Channel during the Thomas Fire. Phytoplankton community composition was described using a combination of images of phytoplankton from the Imaging FlowCytobot (McLane Labs) and phytoplankton pigments. Dinoflagellates were the dominant phytoplankton group in the surface ocean during the Thomas Fire, according to both methods (Figure 1).

Figure 1. (A) The fraction of total particle volume imaged by the Imaging FlowCytobot (IFCB) comprised of phytoplankton (green) and detritus (brown). Example IFCB images of ash (counted as part of detritus) particles are outlined in brown. (B) The phytoplankton fraction is then further divided by taxonomy, showing the abundance of nano-sized phytoplankton and especially dinoflagellates during the week of sampling. Example IFCB images of Gonyaulax (outlined in dark green), Prorocentrum (outlined in light green), and Umbilicosphaera (outlined in purple) cells are also shown.

 

While this study was not able to demonstrate a causal relationship between the Thomas Fire and the presence of dinoflagellates, this result is quite different from previous winters in the Santa Barbara Channel, when picophytoplankton and diatoms typically dominate the winter community. The incidence of dinoflagellates in the Santa Barbara Channel in December 2017 was correlated with the warmer-than-average water temperature during this study, which matched observations from other areas along the Central California coast that winter.

At the time this study was conducted, the Thomas Fire was the largest wildfire in California history. Since then, California fires have increased in danger, destruction, and human mortality; the Mendocino Fire complex (summer 2018) and five separate wildfires in summer 2020 exceeded the impacts of the Thomas Fire. With wildfire severity and frequency increasing not only in California but in coastal regions worldwide, this study gives an important first look at the impact of wildfire smoke and ash on oceanic primary productivity and community composition.

 

Authors:
Sasha Kramer (University of California Santa Barbara)
Kelsey Bisson (Oregon State University)
Alexis Fischer (University of California Santa Cruz)

Does ocean acidification make marine fish grow differently? What about sex-specific effects?

Posted by mmaheigan 
· Monday, February 8th, 2021 

The question of whether ocean acidification (OA) will impact the growth of marine fish remains surprisingly uncertain. The bulk of available evidence in the form of laboratory experiments suggests that most fish are not impacted by OA-relevant CO2 levels, but many studies suffer from the inherent methodical constraints of rearing marine fish in captivity. For example, most experiments cover a small fraction of a species’ lifespan and do not employ restricted feeding regimes which may enable fish to increase feeding to offset metabolic deficits associated with high-CO2 acclimation.

To address these methodological shortcomings, authors of a recent publication in PLOS One synthesized three years of multiple long-term, food-controlled experiments that reared large populations of the model forage fish Menidia menidia (Atlantic silverside) from fertilization to about a third of their lifespan. Results showed modest but consistent negative, temperature-dependent growth effects, in which silversides from high-CO2 treatments were shorter (-3% to -9%) and weighed less (-6% to -18%) than ambient-CO2 conspecifics. However, sometimes it takes more than just looking at means and standard deviations to elucidate these effects. Hence, the authors employed powerful shift functions to analyze how the size distributions of experimental populations shifted to smaller quantiles under future CO2 conditions.

Figure caption: The length of juvenile Atlantic silversides reared from fertilization under control (blue dots) and high-CO2 treatments (red dots). Exposure to OA conditions imposed a universal shift to a smaller body size across the size frequency distribution. Black vertical bars overlaying each distribution indicate the .1, .25, .5, .75, and .9 quantiles and quantile shifts are indicated by connecting lines.

It took over 100 days of continuous high-CO2 exposure until size differences were detectable. This means that long-term CO2 effects could exist in other tested species but are missed in relatively short experiments. Furthermore, the authors sexed several thousand fish to enable a rare sex-specific analysis of CO2 effects. Both sexes were similarly affected by high CO2, and the hormonal pathways that mediate environmental sex determination in this species are not impacted by CO2 level. Our results confirm that Atlantic silversides are relatively tolerant of future OA conditions. But even in this robust estuarine species, high CO2 can reduce growth. This could have cascading effects on population dynamics by impacting size-dependent traits like reproductive success and over-wintering survival of this widespread and ecologically important prey species.

 

Authors
Christopher S. Murray (University of Washington)
Hannes Baumann (University of Connecticut)

 

Warming counteracts acidification in temperate crustose coralline algae communities

Posted by mmaheigan 
· Friday, November 6th, 2020 

Seawater carbonate chemistry has been altered by dramatic increases in anthropogenic CO2 release and global temperatures, leading to significant changes in rocky shore habitats and the metabolism of most marine organisms. There has been recent interest in how these anthropogenic stresses affect crustose coralline algae (CCA) communities because CCA photosynthesis and calcification are directly influenced by seawater carbonate chemistry. CCA is a foundation species in temperate macroalgal communities, where species succession and rocky shore community structure are particularly susceptible to anthropogenic disturbance. In particular, the disappearance of turf and foliose macroalgae caused by climate change and herbivore pressure results in the dominance of CCA (Figure 1a).

Figure 1: (a) Examples of crustose coralline algae (CCA)-dominated seaweed bed in the East Sea of Korea showing barren ground dominated by CCA (bright white and pink color on the rock; see arrows) on a rocky subtidal zone grazed by sea urchins. (b) Specific growth rate of marginal encrusting area under future climate conditions.

In a recent study published in Marine Pollution Bulletin, the authors conducted a mesocosm experiment to investigate the sensitivity of temperate CCA Chamberlainium sp. to future climate stressors, as simulated by three experimental treatments: 1) Acidification: doubled CO2; 2) Warming: +5ºC; and 3) Greenhouse: doubled CO2 and +5ºC. After a 47-day acclimation period, when compared with present-day (control: 490 μatm and 20ºC) conditions, the Acidification treatment showed decreased photosynthesis rates of Chamberlainium sp, whereas the Warming treatment showed increased photosynthesis. The Acidification treatment also showed reduced encrusting growth rates relative to the Control, but when acidification was combined with warming in the Greenhouse treatment, encrusting growth rates increased substantially (Figure 1b). Taken together, these results suggest that the negative ecophysiological responses of Chamberlainium sp to acidification are ameliorated by elevated temperatures in a greenhouse world. In other words, if the foliose macroalgal community responses negatively in the greenhouse environment, the dominance of CCA will increase further, and the biodiversity of the algae community will be reduced.

 

Authors:
Ju-Hyoung Kim (Faculty of Marine Applied Biosciences, Kunsan National University)
Il-Nam Kim (Department of Marine Science, Incheon National University)

Marine heatwave implications for future phytoplankton blooms

Posted by mmaheigan 
· Thursday, October 15th, 2020 

Ocean temperature extreme events such as marine heatwaves are expected to intensify in coming decades due to anthropogenic warming. Although the effects of marine heatwaves on large plants and animals are becoming well documented, little is known about how these warming events will impact microbes that regulate key biogeochemical processes such as ocean carbon uptake and export, which represent important feedbacks on the global carbon cycle and climate.

Figure caption: Relationship between phytoplankton bloom response to marine heatwaves and background nitrate concentration in the 23 study regions. X-axis denotes the annual-mean sea-surface nitrate concentration based on the model simulation (1992-2014; OFAM3, blue) and the in situ climatology (WOA13, orange). Y-axis denotes the mean standardised anomalies (see Equation 1 of the paper) of simulated sea-surface phytoplankton nitrogen biomass (1992-2014; OFAM3, blue) and observed sea-surface chlorophyll a concentration (2002-2018; MODIS, orange) during the co-occurrence of phytoplankton blooms and marine heatwaves.

In a recent study published in Global Change Biology, authors combined model simulations and satellite observations in tropical and temperate oceanographic regions over recent decades to characterize marine heatwave impacts on phytoplankton blooms. The results reveal regionally‐coherent anomalies depicted by shallower surface mixed layers and lower surface nitrate concentrations during marine heatwaves, which counteract known light and nutrient limitation effects on phytoplankton growth, respectively (Figure 1). Consequently, phytoplankton bloom responses are mixed, but derive from the background nutrient conditions of a study region such that blooms are weaker (stronger) during marine heatwaves in nutrient-poor (nutrient-rich) waters.

Given the projected expansion of nutrient-poor waters in the 21st century ocean, the coming decades are likely to see an increased occurrence of weaker blooms during marine heatwaves, with implications for higher trophic levels and biogeochemical cycling of key elements.

Authors:
Hakase Hayashida (University of Tasmania)
Richard Matear (CSIRO)
Pete Strutton (University of Tasmania)

Next Page »

Filter by Keyword

abundance acidification additionality advection africa air-sea air-sea interactions algae alkalinity allometry ammonium AMO AMOC anoxic Antarctic Antarctica anthro impacts anthropogenic carbon anthropogenic impacts appendicularia aquaculture aquatic continuum aragonite saturation arctic Argo argon arsenic artificial seawater Atlantic atmospheric CO2 atmospheric nitrogen deposition authigenic carbonates autonomous platforms bacteria bathypelagic BATS BCG Argo benthic bgc argo bio-go-ship bio-optical bioavailability biogeochemical cycles biogeochemical models biogeochemistry Biological Essential Ocean Variables biological pump biophysics bloom blue carbon bottom water boundary layer buffer capacity C14 CaCO3 calcification calcite carbon carbon-climate feedback carbon-sulfur coupling carbonate carbonate system carbon budget carbon cycle carbon dioxide carbon export carbon fluxes carbon sequestration carbon storage Caribbean CCA CCS changing marine chemistry changing marine ecosystems changing marine environments changing ocean chemistry chemical oceanographic data chemical speciation chemoautotroph chesapeake bay chl a chlorophyll circulation CO2 coastal and estuarine coastal darkening coastal ocean cobalt Coccolithophores commercial community composition competition conservation cooling effect copepod copepods coral reefs CTD currents cyclone daily cycles data data access data assimilation database data management data product Data standards DCM dead zone decadal trends decomposers decomposition deep convection deep ocean deep sea coral denitrification deoxygenation depth diatoms DIC diel migration diffusion dimethylsulfide dinoflagellate dinoflagellates discrete measurements distribution DOC DOM domoic acid DOP dust DVM ecology economics ecosystem management ecosystems eddy Education EEZ Ekman transport emissions ENSO enzyme equatorial current equatorial regions ESM estuarine and coastal carbon fluxes estuary euphotic zone eutrophication evolution export export fluxes export production extreme events faecal pellets fecal pellets filter feeders filtration rates fire fish Fish carbon fisheries fishing floats fluid dynamics fluorescence food webs forage fish forams freshening freshwater frontal zone functional role future oceans gelatinous zooplankton geochemistry geoengineering geologic time GEOTRACES glaciers gliders global carbon budget global ocean global warming go-ship grazing greenhouse gas greenhouse gases Greenland ground truthing groundwater Gulf of Maine Gulf of Mexico Gulf Stream gyre harmful algal bloom high latitude human food human impact human well-being hurricane hydrogen hydrothermal hypoxia ice age ice cores ice cover industrial onset inland waters in situ inverse circulation ions iron iron fertilization iron limitation isotopes jellies katabatic winds kelvin waves krill kuroshio lab vs field land-ocean continuum larvaceans lateral transport LGM lidar ligands light light attenuation lipids low nutrient machine learning mangroves marine carbon cycle marine heatwave marine particles marine snowfall marshes mCDR mechanisms Mediterranean meltwater mesopelagic mesoscale mesoscale processes metagenome metals methane methods microbes microlayer microorganisms microplankton microscale microzooplankton midwater mitigation mixed layer mixed layers mixing mixotrophs mixotrophy model modeling model validation mode water molecular diffusion MPT MRV multi-decade n2o NAAMES NCP nearshore net community production net primary productivity new ocean state new technology Niskin bottle nitrate nitrogen nitrogen cycle nitrogen fixation nitrous oxide north atlantic north pacific North Sea nuclear war nutricline nutrient budget nutrient cycles nutrient cycling nutrient limitation nutrients OA observations ocean-atmosphere ocean acidification ocean acidification data ocean alkalinity enhancement ocean carbon storage and uptake ocean carbon uptake and storage ocean color ocean modeling ocean observatories ocean warming ODZ oligotrophic omics OMZ open ocean optics organic particles oscillation outwelling overturning circulation oxygen pacific paleoceanography PAR parameter optimization parasite particle flux particles partnerships pCO2 PDO peat pelagic PETM pH phenology phosphate phosphorus photosynthesis physical processes physiology phytoplankton PIC piezophilic piezotolerant plankton POC polar polar regions policy pollutants precipitation predation predator-prey prediction pressure primary productivity Prochlorococcus productivity prokaryotes proteins pteropods pycnocline radioisotopes remineralization remote sensing repeat hydrography residence time resource management respiration resuspension rivers rocky shore Rossby waves Ross Sea ROV salinity salt marsh satellite scale seafloor seagrass sea ice sea level rise seasonal seasonality seasonal patterns seasonal trends sea spray seawater collection seaweed secchi sediments sensors sequestration shelf ocean shelf system shells ship-based observations shorelines siderophore silica silicate silicon cycle sinking sinking particles size SOCCOM soil carbon southern ocean south pacific spatial covariations speciation SST state estimation stoichiometry subduction submesoscale subpolar subtropical sulfate surf surface surface ocean Synechococcus technology teleconnections temperate temperature temporal covariations thermocline thermodynamics thermohaline thorium tidal time-series time of emergence titration top predators total alkalinity trace elements trace metals trait-based transfer efficiency transient features trawling Tris trophic transfer tropical turbulence twilight zone upper ocean upper water column upwelling US CLIVAR validation velocity gradient ventilation vertical flux vertical migration vertical transport warming water clarity water mass water quality waves weathering western boundary currents wetlands winter mixing zooplankton

Copyright © 2025 - OCB Project Office, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, MS #25, Woods Hole, MA 02543 USA Phone: 508-289-2838  •  Fax: 508-457-2193  •  Email: ocb_news@us-ocb.org

link to nsflink to noaalink to WHOI

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.