Simulations With the Marine Biogeochemistry Library (MARBL)

Long, Matthew C.; Moore, J. Keith; Lindsay, Keith; Levy, Michael; Doney, Scott C.; Luo, Jessica Y.; Krumhardt, Kristen M.; Letscher, Robert T.; Grover, Maxwell; Sylvester, Zephyr

doi:10.1029/2021ms002647

Cited by 67 publications

(87 citation statements)

References 149 publications

(213 reference statements)

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“…Phytoplankton responses to climate change in the Southern Ocean also agree. In a CCSM (Community Climate System Model, a previous version of CESM) simulation run under a high emission scenario, diatom growth rates increased in the subpolar region of the Southern Ocean (Marinov et al, 2010), as did diatom productivity in simulations with the latest version of CESM (CESM version 2; Long et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Climate drivers of Southern Ocean phytoplankton community composition and potential impacts on higher trophic levels

et al. 2022

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Southern Ocean phytoplankton production supports rich Antarctic marine ecosystems comprising copepods, krill, fish, seals, penguins, and whales. Anthropogenic climate change, however, is likely to drive rearrangements in phytoplankton community composition with potential ramifications for the whole ecosystem. In general, phytoplankton communities dominated by large phytoplankton, i.e., diatoms, yield shorter, more efficient food chains than ecosystems supported by small phytoplankton. Guided by a large ensemble of Earth system model simulations run under a high emission scenario (RCP8.5), we present hypotheses for how anthropogenic climate change may drive shifts in phytoplankton community structure in two regions of the Southern Ocean: the Antarctic Circumpolar Current (ACC) region and the sea ice zone (SIZ). Though both Southern Ocean regions experience warmer ocean temperatures and increased advective iron flux under 21st century climate warming, the model simulates a proliferation of diatoms at the expense of small phytoplankton in the ACC, while the opposite patterns are evident in the SIZ. The primary drivers of simulated diatom increases in the ACC region include warming, increased iron supply, and reduced light from increased cloudiness. In contrast, simulated reductions in ice cover yield greater light penetration in the SIZ, generating a phenological advance in the bloom accompanied by a shift to more small phytoplankton that effectively consume available iron; the result is an overall increase in net primary production, but a decreasing proportion of diatoms. Changes of this nature may promote more efficient trophic energy transfer via copepods or krill in the ACC region, while ecosystem transfer efficiency in the SIZ may decline as small phytoplankton grow in dominance, possibly impacting marine food webs sustaining Antarctic marine predators. Despite the simplistic ecosystem representation in our model, our results point to a potential shift in the relative success of contrasting phytoplankton ecological strategies in different regions of the Southern Ocean, with ramifications for higher trophic levels.

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Section: Discussionmentioning

confidence: 99%

Climate drivers of Southern Ocean phytoplankton community composition and potential impacts on higher trophic levels

et al. 2022

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“…When oxygen concentration is <5 μM, nitrate is consumed rather than oxygen during the remineralization of this organic matter (J. K. Moore & Doney, 2007). The model has one class of explicit, iron‐binding ligands and external iron sources from atmospheric deposition (pyrogenic and mineral dust sourced iron), marine sediments, hydrothermal vents, and riverine inputs (Long et al., 2021; J. K. Moore & Braucher, 2008). We ran the simulations with constant pre‐industrial CO 2 for 300 years and averaged the results over the last 20 years of the simulation.…”

Section: Methodsmentioning

confidence: 99%

“…The ratio of coarse/fine dust at deposition is a useful proxy for the distance traveled from the mineral dust source regions, as the coarse dust particles are expected to be removed more quickly during atmospheric transport. The dust iron solubility in CESM2 is a function of the ratio of coarser dust particle deposition/finer dust particle deposition (Long et al., 2021). The approach gives low solubilities near dust sources (∼0.5%) increasing to greater than 10% in the most remote regions in the central Pacific, capturing the observed relationship between deposition rate and iron solubility seen in observations (Sholkovitz et al., 2012).…”

Section: Methodsmentioning

confidence: 99%

Acclimation of Phytoplankton Fe:C Ratios Dampens the Biogeochemical Response to Varying Atmospheric Deposition of Soluble Iron

Wiseman

Moore

Twining

et al. 2023

Global Biogeochemical Cycles

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Dissolved iron (dFe) plays an important role in regulating marine productivity. In high nutrient, low chlorophyll regions (>33% of the global ocean), iron is the primary growth limiting nutrient, and elsewhere iron can regulate nitrogen fixation by diazotrophs. The link between iron availability and carbon export is strongly dependent on the phytoplankton iron quotas or cellular Fe:C ratios. This ratio varies by more than an order of magnitude in the open ocean and is positively correlated with ambient dFe concentrations in field observations. Representing Fe:C ratios within models is necessary to investigate how ocean carbon cycling will interact with perturbations to iron cycling in a changing climate. The Community Earth System Model ocean component was modified to simulate dynamic, group‐specific, phytoplankton Fe:C that varies as a function of ambient iron concentration. The simulated Fe:C ratios improve the representation of the spatial trends in the observed Fe:C ratios. The acclimation of phytoplankton Fe:C ratios dampens the biogeochemical response to varying atmospheric deposition of soluble iron, compared to a fixed Fe:C ratio. However, varying atmospheric soluble iron supply has first order impacts on global carbon and nitrogen fluxes and on nutrient limitation spatial patterns. Our results suggest that pyrogenic Fe is a significant dFe source that rivals mineral dust inputs in some regions. Changes in dust flux and iron combustion sources (anthropogenic and wildfires) will modify atmospheric Fe inputs in the future. Accounting for dynamic phytoplankton iron quotas is critical for understanding ocean biogeochemistry and projecting its response to variations in atmospheric deposition.

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“…where I s and I c are the daily-averaged saturating and compensating irradiance (W/m 2 ), f is the fraction of daylight that is implemented to account for periods of darkness, and I is the irradiance reaching an underwater depth of 2 m. The irradiance is attenuated following the implementation in the Marine Biogeochemistry Library (MRBL) 77,78 .…”

Section: Growthmentioning

confidence: 99%

Biophysical potential and uncertainties of global seaweed farming

Arzeno-Soltero¹,

Frieder²,

Saenz³

et al. 2022

Preprint

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International climate goals require over 5 gigatons/year (Gt/year) of CO2 to be removed from the atmosphere by midcentury. Macroalgae mariculture has been proposed as a strategy for such carbon dioxide removal (CDR). However, the global potential for seaweed cultivation has not been assessed in detail. Here, we develop and use a dynamic seaweed growth model, the Global MacroAlgae Cultivation MODeling System (G-MACMODS), to estimate potential yields of four different types of seaweed worldwide, and test the sensitivity of these estimates to uncertain biophysical parameters under two nutrient scenarios (one in which the surface ocean nutrient budget is unaltered by the presence of seaweed farms, and another in which seaweed harvest is limited by nutrients that are resupplied by vertical transport). We find that 1 Gt of seaweed carbon could be harvested in 0.8% of global exclusive economic zones (EEZs; equivalent to ~1 million km2) if farms were located in the most productive areas, but potential harvest estimates are highly uncertain due to ill-constrained seaweed mortality and nitrogen exudation rates. Our results suggest that seaweed farming could produce climate-relevant quantities of biomass carbon and highlight key uncertainties to be resolved by future research.

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Simulations With the Marine Biogeochemistry Library (MARBL)

Cited by 67 publications

References 149 publications

Climate drivers of Southern Ocean phytoplankton community composition and potential impacts on higher trophic levels

Climate drivers of Southern Ocean phytoplankton community composition and potential impacts on higher trophic levels

Acclimation of Phytoplankton Fe:C Ratios Dampens the Biogeochemical Response to Varying Atmospheric Deposition of Soluble Iron

Biophysical potential and uncertainties of global seaweed farming

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