mmaheigan :: Ocean Carbon & Biogeochemistry

Studying marine ecosystems and biogeochemical cycles in the face of environmental change

Author Archive for mmaheigan – Page 5

BGC Argo Webinar #8, Oct 16 Comparing BGC-Argo observations with models

Posted by mmaheigan

· Tuesday, September 24th, 2024

BGC Argo Webinar #8: Comparing BGC-Argo observations with models
October 16, 2024, 11am Pacific/2pm Eastern

Please join us for the quarterly GO-BGC webinar, hosted by the US Ocean Carbon and Biogeochemistry Project Office. This webinar will be focused on comparisons between BGC-Argo observations and ocean model simulations focusing on bbp and particulate forms of carbon. The webinar will begin with an update on the status of the GO-BGC float array, followed by two short presentations. We’ll then close with a community discussion and Q&A session. Recordings will be available on the OCB and GO-BGC websites.

1) Yui Takeshita (Monterey Bay Aquarium Research Institute, USA, yui@mbari.org): An update on the GO-BGC program

2) Camila Serra-Pompei (Technical University of Denmark): Assessing the potential of backscattering as a proxy for phytoplankton carbon biomass
The particulate backscattering coefficient (bbp) has often been used as an optical proxy to estimate phytoplankton carbon biomass (Cphy). However, total observed bbp is impacted by phytoplankton size, cell composition, and non-algal particles. The scarcity of phytoplankton carbon field data has prevented the quantification of uncertainties driven by these factors. Here, we first review and discuss existing bbp algorithms by applying them to bbp data from the BGC-Argo array in surface waters (<10m) and show that errors can be large when the bbp signal is low. Next, we use a global ocean circulation model (the MITgcm Biogeochemical and Optical model) that simulates plankton dynamics and associated inherent optical properties to quantify and understand uncertainties from bbp-based algorithms in surface waters. In an ideal world where field data has no methodological uncertainties, the model shows that bbp algorithms could estimate phytoplankton carbon biomass with an absolute error close to 20% in most regions.

3) Martí Galí Tàpias (Institute of Marine Sciences [ICM-CSIC], Spain): Constraining stocks and fluxes of Particulate Organic Carbon (POC) through the comparison between particulate backscattering measurements and the PISCESv2 model
BGC-Argo data offers a great opportunity for model evaluation, optimization, and the development of improved parameterizations, ultimately furthering our mechanistic understanding. However, comparison between BGC-Argo observations and models requires careful consideration of the spatiotemporal scales that each of them can resolve. When using particulate backscattering (bbp) as a proxy for particulate organic carbon (POC), additional attention must be paid to the variability in the POC/bbp ratio, its uncertainty, and its underpinning biogeochemical drivers. In this talk I will present comparisons between bbp from BGC-Argo and simulated POC based on both 3D (Eulerian) and 1D (pseudo-Lagrangian) frameworks. I will discuss the potential and limitations of model parameter optimization using BGC-Argo bbp as the observational reference. Finally, I will explore the impacts of optimized model parameters on mesopelagic POC budgets and vertical fluxes in the PISCESv2 model.

4) Discussion

Fast-sinking salp and fish detritus impacts OMZ size and ocean biogeochemical cycles

Posted by mmaheigan

· Thursday, September 12th, 2024

Marine fishes and filter-feeding gelatinous zooplankton such as salps and pyrosomes generate detritus in the form of poop and dead carcasses, which sink ~10 times faster than other oceanic detritus. This detritus is hypothesized to have a disproportionally large impact on the marine biological pump as it sequesters carbon and nutrients deeper in the water column. Until now, global models had not considered these fluxes, thus, their impacts on ocean biogeochemical cycles were not well understood.

A recent study in Geophysical Research Letters investigated the sensitivity of deep ocean carbon, oxygen, and nutrient cycles to fast-sinking detritus from filter-feeding gelatinous zooplankton (pelagic tunicates) and fishes, using a modified version of the NOAA-GFDL ocean biogeochemical model COBALT (“GZ-COBALT”). We found the fast-sinking detritus decreased surface productivity and export, while increasing transfer efficiency and sequestration at depth. Ocean oxygen minimum zones (OMZs) also decreased in size: fast-sinking detritus triggered less remineralization, particularly in the mid-depths, resulting in less oxygen consumption and a reduced expansion of OMZs.

Figure caption: Flux of detrital carbon at various depths (A, B, C), shows that incorporating fast-sinking detritus counter-intuitively decreases carbon export from the surface while increasing sequestration at depth. Particulate organic carbon (POC) export flux at (A) 100 m, (B) 1,000 m and (C) seafloor (mgC/m2/d), shows (left) the control simulation with no fast-sinking detritus, (center) the experiment with fast-sinking fish and gelatinous zooplankton detritus, and (right) the differences between the control and fast-sinking detritus simulation. (D) Total ocean volume over the 300-year simulation at the suboxic (O2 ≤ 5 mmol/m3) level, shows the simulation with fast-sinking particulate organic carbon (red) had lower suboxia than the control (black). Large hypoxic and suboxic zones are a common model bias; these results suggest that fast-sinking detritus may be one biogeochemical mechanism to reduce the expansion of these low oxygen zones.

Past observations have shown that fast-sinking, highly reactive detritus reaching the seafloor can fuel significant benthic consumption and respiration. On a global scale, we suggest that the increased fluxes to the seafloor in the model can be supported by observational constraints of seafloor oxygen consumption, suggesting that these processes could be realistically incorporated into future generations of Earth System Models.

Authors
Jessica Y. Luo (NOAA GFDL)
Charles A. Stock (NOAA GFDL)
John P. Dunne (NOAA GFDL)
Grace K. Saba (Rutgers University)
Lauren Cook (Rutgers University)

The fate of the 21st century marine carbon cycle could hinge on zooplankton’s appetite

Posted by mmaheigan

· Wednesday, September 11th, 2024

Both climate change and the efforts to abate have the potential to reshape phytoplankton community composition, globally. Shallower mixed layers in a warming ocean and many marine CO₂ removal (CDR) technologies will shift the balance of light, nutrients, and carbonate chemistry, benefiting certain species over others. We must understand how such shifts could ripple through the marine carbon cycle and modify the ocean carbon reservoir. Two new publications in Geophysical Research Letters and Global Biogeochemical Cycles highlight an often over looked pathway in this response: The appetite of zooplankton.

We have long known that the appetite of zooplankton—i.e. the half-saturation concertation for grazing—varies dramatically. This variability is largely based on laboratory incubations of specific species. An open-ocean perspective has been much more elusive. Using two independent inverse modelling approaches, both studies reached the same conclusion: Even at the community level, the appetite of zooplankton in the open-ocean is incredibly diverse.

Moreover, variability in zooplankton appetites maps well onto the biogeography of phytoplankton species. As these phytoplankton niches evolve, the composition of the zooplankton will likely follow. To help understand the impact of this response on the biological pump, we compared two models, one with only two types of zooplankton, and another with an unlimited amount, each with different appetites, all individually tuned to their unique environment. Including more realistic diversity reduced the strength of the biological pump by 1 PgC yr^-1.

Figure Caption. A) Variability in the abundance and characteristic composition of phytoplankton drives B) large differences in the associated appetite and characteristic composition of zooplankton in two independent inverse modelling studies. C) When more realistic diversity in the appetite of zooplankton is simulated in models, the strength of biological pump is dramatically reduced.

That is the same order as the most optimistic scenarios for ocean iron fertilization. This means that when simulating the efficacy of many CDR scenarios, the bias introduced by insufficiently resolved zooplankton diversity could be just as large as the signal. Moving forward, it is imperative to improve the representation of zooplankton in Earth System Models to understand how the marine carbon sink will respond to inadvertent and deliberate perturbations.

Authors (GRL):
Tyler Rohr (The University of Tasmania; Australian Antarctic Program Partnership)
Anthony Richardson (The University of Queensland; CSIRO)
Andrew Lenton (CSIRO)
Matthew Chamberlain (CSIRO)
Elizabeth Shadwick (Australian Antarctic Program Partnership; CSIRO)

Authors (GBC):
Sophie Meyjes (Cambridge)
Colleen Petrick (Scripps Institute of Oceanography)
Tyler Rohr (The University of Tasmania; Australian Antarctic Program Partnership)
B.B. Cael (NOC)
Ali Mashayek (Cambridge)

PACE introduction course – free in english and in spanish

Posted by mmaheigan

· Tuesday, August 27th, 2024

Introduction to Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) Hyperspectral Observations for Water Quality Monitoring

This online, introductory course will be cost-free and have three, 1.5-hour parts:

Part 1: Introduction to the PACE Mission for Water Quality Monitoring (September 25^th)

Part 2: Overview, Access, and Analysis of PACE Ocean Color Data Products (October 2^nd)

Part 3: Access and Visualization of PACE-OCI Data using Python/Jupyter Notebook Software (October 9^th)

Registration is now open – course will be offered in English AND Spanish!

For more information and to register visit:

ENGLISH: https://appliedsciences.nasa.gov/get-involved/training/english/arset-introduction-plankton-aerosol-cloud-ocean-ecosystem-pace

SPANISH: https://appliedsciences.nasa.gov/get-involved/training/english/arset-introduccion-los-datos-hiperespectrales-de-la-mision-plankton

NASA’s ARSET program offers free, online training on using Earth Observations for decision making that are open to the public. Courses are designed for a broad audience, ranging from introductory to advanced. For more on ARSET and to see their wealth of upcoming and previous trainings, please visit their website.

Apply to Attend Leaky Deltas Workshop in March 2025

Posted by mmaheigan

· Tuesday, August 27th, 2024

OCB Scoping Workshop Leaky Deltas: Sources or sinks in the global carbon cycle?
March 17-20, 2025 at Louisiana State Univ. (Baton Rouge, LA)

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 transfer between (i.e., to and from) land to ocean.

Recent evidence suggests that coastal oceans have become net sinks for atmospheric CO2 during post-industrial times and continued human pressures in coastal zones. Alterations to deltas will likely have an important impact on the future evolution of the coastal ocean’s carbon budget.

NOTE This workshop has multiple deadline options: early (if you need a visa to attend), mid (if you want to apply for travel support), and a final deadline for all applications.

Apply to attend Leaky Deltas workshop

Learn more on the workshop webpage.

Apply to a workshop on ethics and governance – mCDR participation wanted!

Posted by mmaheigan

· Friday, August 9th, 2024

Applications for a workshop on ethics and governance for (all forms of) climate interventions have just opened:

https://apply.knowinnovation.com/climateintervention/

NSF OCE will be sending out a “KandyGram” with this information soon.

The application deadline is August 23^rd and we’d like to see good representation for mCDR.

Plankton plummet in one of the world’s longest time series

Posted by mmaheigan

· Friday, August 2nd, 2024

Phytoplankton are the main primary producers in the ocean and fuel marine food webs. Long-term shifts in phytoplankton biomass are useful for understanding the context of short-term changes and for examining the relationships between climate indices and phytoplankton dynamics. However, current monitoring programs often offer too short a time frame to disentangle these relationships.

In a recent publication in the Proceedings of the National Academy of Sciences, data from the Narragansett Bay, RI Long-Term Plankton Time Series, were used to examine long-term trends in Chlorophyll a, a proxy for phytoplankton biomass. The magnitude of the winter-spring bloom and of annual phytoplankton biomass declined by about half from 1968 to 2019 (Figure 1). The winter–spring bloom, which fuels coastal ecosystems, occurred about five days earlier each decade. The authors found these changes were associated with multiple environmental factors impacted by climate change, including warming surface seawater temperatures and reduced nutrient concentrations.

Figure 1: In addition to long-term trends, the authors observed that phytoplankton biomass in Narragansett Bay was highly variable similar to other coastal and open ocean time series they analyzed. A high degree of variation in phytoplankton biomass means that it can take decades to identify a trend from the noise in a dataset. This highlights the need to sustain ecosystem monitoring of phytoplankton and other environmental factors for the long term globally. These results provide the first step to understanding the effect of climate change and anthropogenic inputs at the base of the food web, which will inform future research to determine how this change implicates the rest of the ecosystem.

A major secondary component of this study was the digitization of much of the historical dataset from 1959-1999, which required the lead author to obtain, organize, and digitally record 30 years of physical data from a storage closet and harmonize it with digitized data from 2000-2019. All biological and environmental data from this time series are now publicly available at BCO-DMO for scientists, managers, and educators to explore and utilize.

Authors:
Patricia S. Thibodeau (University of New England) @PattyPlankton
Gavino Puggioni (University of Rhode Island)
Jacob Strock (University of Rhode Island)
David G. Borkman (Rhode Island Department of Environmental Management, Office of Water Resources–Shellfish)
Tatiana A. Rynearson (University of Rhode Island) @RynearsonLab

A New Insight into Ocean Carbon Sequestration

Posted by mmaheigan

· Thursday, August 1st, 2024

How does the microbial carbon pump (MCP) redefine our understanding of oceanic carbon sequestration and climate change mitigation?

A recent study published in Nature Reviews Microbiology reviews the pivotal role of the microbial carbon pump (MCP) a novel concept differing from the known mechanisms for carbon sequestration in the ocean, the Biological Carbon Pump (BCP), the Carbonate Counter Pump (CCP), and the Solubility Carbon Pump (SCP) (Figure 1).

Figure 1 Illustration of the microbial carbon pump (MCP) and other carbon pumps, outlining their relationships and modes of carbon transformation and sequestration in the ocean.

Unlike the others, the MCP operates independently of physical processes like vertical transportation and sedimentation; it is driven by microbial processes at every depth in the water column, and functions as a two-way pump of carbon cycle, thus playing a unique role in regulation of climate change. The MCP’s role in transforming dissolved organic carbon (DOC) from labile states into refractory states, reveals the “enigma” of how the oceanic refractory DOC (RDOC) reservoir is formed. This paper also illustrates the dual functions of the MCP-regulated oceanic carbon reservoir over geological timescales, which may help explain the “eccentricity puzzle” in the Milankovitch climate theory.

The spatial and temporal distribution of RDOC is influenced by various microbial processes and the paper details how the MCP responds to environmental changes across environmental gradients and the entire water column. We also revealed the impacts of climate change on microbial activities and carbon sequestration efficiency, which in turn affect carbon cycles across different oceanic regions and depths. We explored the synergistic effects of the MCP with BCP, CCP, and SCP (BCMS), which could have great potentials in geoengineering. Applications of BCMS approach make it possible for international program on Ocean Negative Carbon Emissions (ONCE) practice for both of carbon sink enhancement and ecosystem sustainable development, such as scenarios of sea-farming areas and wastewater treatment plants, avoiding the potential risks of traditional geoengineering approaches.

Understanding the MCP processes and effects is essential for accurate assessment of the ocean’s capacity to mitigate climate change, and how the MCP can support potential modes of geoengineering. The findings and implications are of profound reference for policymakers, environmental stakeholders, and funding agencies for strategies to fight climate changes, leverage more effective preservation and restoration of ecosystems.

Authors:
Nianzhi Jiao (Xiamen University)
Tingwei Luo (Xiamen University)
Quanrui Chen (Xiamen University)
Zhao Zhao (Xiamen University)
Xilin Xiao (Xiamen University)
Jihua Liu (Shandong University)
Zhimin Jian (Tongji University)
Shucheng Xie (China University of Geosciences)
Helmuth Thomas (Helmholtz-Zentrum Hereon)
Gerhard J. Herndl (University of Vienna)
Ronald Benner (University of South Carolina)
Micheal Gonsior (University of Maryland)
Feng Chen (University of Maryland)
Wei-Jun Cai (University of Delaware)
Carol Robinson (University of East Anglia)

Out of sight, out of mind: extreme signals of ocean acidification hidden in the mesopelagic

Posted by mmaheigan

· Wednesday, July 31st, 2024

Ocean Acidification (OA), caused by the air-to-sea transfer of anthropogenic carbon (C_ant), is intuitively thought to be a surface-intensified process, which makes sense because the concentration of C_ant is greatest near the ocean surface and decreases with depth. But this intuition is not correct for multiple metrics of OA that are less commonly studied below the sea surface, including the partial pressure of carbon dioxide gas (pCO₂) and the hydrogen ion concentration ([H⁺]).

We braved the quiescent seas of a three-dimensionally mapped data product (Lauvest et al., 2016) hunting for signals of OA in the deep. Just like anyone who seeks moss in Seattle, we were successful. We identified massive interior ocean changes in pCO₂ and [H⁺] caused by the accumulation of C_ant (up to the year 2002). Such signals were not clearly identifiable for the more commonly studied pH and aragonite saturation state OA metrics. Extreme pCO₂ and [H⁺] changes induced by smaller amounts of C_ant at depth are caused by greater sensitivities of these parameters to carbon addition in subsurface waters that are weakly buffered because they have experienced significant organic matter respiration. This results in mesopelagic pCO₂ (and [H⁺]) changes that are more than twice as large as overlying surface water changes throughout large expanses of the ocean, outpacing the atmospheric pCO₂ change that drives OA itself (ΔpCO_{2 Air} of ~92 μatm in year 2002).

Yikes! What should we investigate next? Well, it may be that the re-emergence of high-pCO₂, mesopelagic waters at the sea surface could cause elevated CO₂ evasion rates and reduced carbon storage efficiency in regions where waters do not have time to fully equilibrate with the atmosphere before subduction. It is also possible that the elevated signal-to-noise ratio associated with subsurface pCO₂ and [H⁺] changes could prove useful in the assessment of environmental impacts associated with some marine carbon dioxide removal strategies. More work is needed to characterize the evolution of mesopelagic OA metric changes beyond the year 2002, and what they could mean for ocean ecosystems that are already under pressure from a variety of anthropogenic stressors.

Authors:
Andrea J. Fassbender (NOAA Pacific Marine Environmental Laboratory)
Brendan R. Carter (Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington)
Jonathan D. Sharp (Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington)
Yibin Huang (Xiamen University)
Mar C. Arroyo (University of California Santa Cruz)
Hartmut Frenzel (Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington)

Publication: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023GB007843

OCB Supports Early Career Participants in Cornell Satellite Remote Sensing Training Program

Posted by mmaheigan

· Thursday, July 25th, 2024

OCB Supports Early Career Participants in Cornell Satellite Remote Sensing Training Program 2024

María del Alma Concepción Rodríguez

Alba Guzman-Morales

Kiwanuka Moses

Michelle Wagner

Michelle Wagner is in her first year of master’s study at the City College of New York. Her research interest is in monitoring the responses of coastal systems to natural and anthropogenic stressors. After graduating from the City College of New York, Michelle joined the Tzortziou Bio-optics lab at CCNY. Her work utilized HPLC and microscopic analysis as well remote sensing data to characterize seasonal shifts in phytoplankton community composition in the Long Island Sound estuary and increasing intensity in red tide events and other HABS.

I am very happy to have been a part of the Cornell 2024 Satellite Remote Sensing Training Program this summer. As someone who is new to the world of satellite data processing, I could not have asked for a better introduction. Dr. Monger’s strong expertise as well as his guidance and encouragement gave me the confidence to tackle hard problems. The course not only introduced me to Python programming but also provided a range of tools for handling satellite data. It significantly broadened my perspective and deepened my understanding of satellite remote sensing. I really enjoyed this course and would recommend it to anyone pursuing satellite remote sensing and ocean color analysis. I would like to say thank you to Dr. Bruce Monger and OCB for this amazing experience!

Alba Guzmán Morales was born in Arecibo, Puerto Rico. She received her B.S. in Biology and M.S. in Biological Oceanography from the University of Puerto Rico Mayagüez Campus in 2019 and 2024, respectively. Her research focused on using satellite imagery to study water clarity trends in Puerto Rico to evaluate management efforts in a watershed. As a NOAA Cooperative Science Center in Atmospheric Sciences and Meteorology Fellow, she evaluated the applicability of a NOAA Kd490 product by comparing it with in situ Kd490. She has also been involved in Unmanned Aerial Vehicle research to measure salinity.

Cornell's Satellite Remote Sensing course was what I expected and more. While I had previous experience processing satellite data the course provided me with tools I hadn’t yet had the opportunity to use in my work. It was amazing to process and visualize L1 to L2 ocean color, SST, wind, and altimetry data. I am deeply thankful to the great instructors Dr. Bruce Monger and Jillian Steinmetz, to the colleagues I met during the course as well as OCB for supporting this opportunity. Let the research continue!

Kiwanuka Moses: I’m a second-year Earth Systems Science PhD Student working under Dr. Sridhar Maruthi Balaji Bhaskar at Florida International University. My research uses remote sensing and machine learning to estimate water quality parameters for inland lakes (Okeechobee and Victoria). The goal is to develop monitoring algorithms based on Landsat 8 OLI and Sentinel 2 MSI images. These models will be correlated with results from NASA SeaDAS software.

The Cornell Satellite Remote Sensing course was a great experience. I learned multiple ways of downloading datasets, cleaning them, and channeling them to a particular study area. I also learned how to use Python command lines for image processing using NASA SeaDAS and better understood the different components of oceanography (Physical and biological) as a field. There was a great improvement in my programming skills. I enjoyed every moment with Dr. Bruce Monger and Ms. Jillian Elaine, the TA. Their patience regarding the questions directed at them was exceptional. I recommend this course to anyone interested in remote sensing and ocean color. Special thanks to Ocean Carbon and Biogeochemistry (OCB) for the sponsorship and for making this a reality for me.

María del Alma Concepción Rodríguez's journey into water resources began during her undergraduate studies at the Polytechnic University of Puerto Rico. Earning a Bachelor of Science in Chemical Engineering and a master’s in environmental management, she immersed herself in internships and projects related to the water industry. These experiences profoundly impacted her, highlighting water's vital role as the driving force of nature and the center of life.

As she advanced to her PhD in Civil Engineering, now going into her third year, María del Alma’s passion for water conservation grew stronger. She became particularly concerned about the potential contamination from regulated wastewater disposals in the waters surrounding the Caribbean Island of Puerto Rico. This concern sparked a compelling desire to delve deeper into understanding their impacts. Her doctoral research is a testament to this dedication. It focuses on how effluent discharges affect oceanic waters and aims to develop a comprehensive evaluation methodology. María del Alma leverages innovative GIS techniques to identify contamination hotspots through spatial data analysis. Her goal is to create geospatial models that visualize current and future scenarios, providing a clearer picture of the potential impacts on our waters.

Through her work, María del Alma strives to protect and conserve our natural environment, recognizing that safeguarding water resources is not just important but essential.

Imagine learning about the intricacies of satellite remote sensing while collaborating with peers, all within the vibrant academic atmosphere of Cornell University—that was my experience in a nutshell. The 2024 Cornell Satellite Remote Sensing Summer Course was an enriching experience that deepened my technical knowledge and connected me with a network of passionate individuals in the remote sensing community. The course’s rigorous curriculum laid a strong foundation for my understanding of the field and opened my eyes to the vast remote sensing applications. We delved into the core principles of remote sensing, how the satellite data is collected, and the processing of such data using coding. Dr. Bruce Monger was an excellent instructor who guided us throughout the course while getting a better understanding of each of our investigations. Teaching assistant Jillian Steinmetz was knowledgeable and always willing to assist us. The course featured lectures and hands-on workshops where you were given exercises to work on the computer using Python and SeaDAS to understand the processing of satellite imagery. One of the most exciting moments of the course was the hands-on experience with satellite data—using advanced software to process and analyze the data and turn the raw information into meaningful insights for my PhD research. Participating in the 2024 Cornell Satellite Remote Sensing Training Program was a transformative experience that broadened my horizons and passion for using innovative technology in real-world water applications.

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.

Author Archive for mmaheigan – Page 5

OCB Supports Early Career Participants in Cornell Satellite Remote Sensing Training Program 2024

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