Primary production dynamics during the decline phase of the North Atlantic annual spring bloom

Meyer, Meredith G.; Brzezinski, Mark A.; Cohn, Melanie R; Kramer, Sasha J.; Paul, Nigel D.; Sharpe, Garrett C; Niebergall, Alexandria K.; Gifford, Scott M.; Cassar, Nicolas; Marchetti, Adrian

doi:10.1101/2023.05.18.541304

Cited by 5 publications

(18 citation statements)

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“…We observed substantial dynamics in N. Atlantic respiration rates driven by the decline of a phytoplankton bloom and multiple mixing events. Here, large phytoplankton were more prevalent than in the N. Pacific (Meyer et al, 2023). Accordingly, our N. Atlantic whole water respiration rates were, on average, 1.4fold higher than the N. Pacific and small size-fraction rates were, on average, 1.3-fold lower.…”

Section: The Dynamic North Atlantic End Membermentioning

confidence: 51%

“…At PAP, we initially observed a declining, large phytoplankton bloom, marked by reduced primary production and chlorophyll-a levels (Meyer et al, 2023). During this period, surface whole water and small-fraction respiration decreased (Figure 7B).…”

Section: N Atlantic Respiration Rate Temporal Dynamicsmentioning

confidence: 89%

“…However, whole water respiration rates had two significant increases, corresponding to mixing during the first storm and first wind periods. Notably, a peak in deep water respiration rates was observed at the end of the first wind period, coinciding with a major flux event and an increase in particulate carbon (Meyer et al, 2023).…”

Section: N Atlantic Respiration Rate Temporal Dynamicsmentioning

confidence: 99%

“…Chlorophyll-a and net primary production were performed in the Pacific and N. Atlantic as reported in Meyer et al (Meyer et al, 2022(Meyer et al, , 2023. Briefly, net primary production (24 h 13 C uptake incubation) was estimated based on samples collected at the surface on the same days as respiration assays in the N. Pacific and at the same rosette casts as respiration assays in the N. Atlantic.…”

Section: Chlorophyll-a and Primary Productionmentioning

confidence: 99%

“…In this study, we evaluated size-fractionated microbial respiration rates in two contrasting oceanic regions using O 2 consumption assays and optode measurements: the low productivity and low carbon export area of the North Pacific Ocean at Station Papa (Wong et al, 1995;Boyd and Harrison, 1999;Meyer et al, 2022), and the high productivity North Atlantic Porcupine Abyssal Plain (PAP) (Fasham et al, 1999;Frigstad et al, 2015;Meyer et al, 2023). For the N. Pacific, respiration rates were determined using a single, manually applied fiber optic cable to obtain optode readings.…”

Section: Introductionmentioning

confidence: 99%

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Microbial respiration in contrasting ocean provinces via high-frequency optode assays

Cohn,

Stephens,

Meyer

et al. 2024

Front. Mar. Sci.

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Microbial respiration is a critical component of the marine carbon cycle, determining the proportion of fixed carbon that is subject to remineralization as opposed to being available for export to the ocean depths. Despite its importance, methodological constraints have led to an inadequate understanding of this process, especially in low-activity oligotrophic and mesopelagic regions. Here, we quantify respiration rates as low as 0.2 µmol O2 L-1 d-1 in contrasting ocean productivity provinces using oxygen optode sensors to identify size-fractionated respiration trends. In the low productivity region of the North Pacific Ocean at Station Papa, surface whole water microbial respiration was relatively stable at 1.2 µmol O2 L-1 d-1. Below the surface, there was a decoupling between respiration and bacterial production that coincided with increased phytodetritus and small phytoplankton. Size-fractionated analysis revealed that cells <5 µm were responsible for the majority of the respiration in the Pacific, both at the surface and below the mixed layer. At the North Atlantic Porcupine Abyssal Plain, surface whole water microbial respiration was higher (1.7 µmol O2 L-1 d-1) than in the Pacific and decreased by 3-fold below the euphotic zone. The Atlantic size-fraction contributions to total respiration shifted on the order of days during the evolution of a phytoplankton bloom with regular storm disturbances. The high-resolution optode method used in the Atlantic captured these significant shifts and is consistent with coinciding stain-based respiration methods and historical site estimates. This study highlights the dynamic nature of respiration across vertical, temporal, and size-fractionated factors, emphasizing the need for sensitive, high-throughput techniques to better understand ocean ecosystem metabolism.

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Section: The Dynamic North Atlantic End Membermentioning

confidence: 51%

Section: N Atlantic Respiration Rate Temporal Dynamicsmentioning

confidence: 89%

Section: N Atlantic Respiration Rate Temporal Dynamicsmentioning

confidence: 99%

Section: Chlorophyll-a and Primary Productionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microbial respiration in contrasting ocean provinces via high-frequency optode assays

Cohn,

Stephens,

Meyer

et al. 2024

Front. Mar. Sci.

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Physical Mechanisms Sustaining Silica Production Following the Demise of the Diatom Phase of the North Atlantic Spring Phytoplankton Bloom During EXPORTS

Brzezinski,

Johnson,

Estapa

et al. 2024

Global Biogeochemical Cycles

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Each spring, the North Atlantic experiences one of the largest open‐ocean phytoplankton blooms in the global ocean. Diatoms often dominate the initial phase of the bloom with succession driven by exhaustion of silicic acid. The North Atlantic was sampled over 3.5 weeks in spring 2021 following the demise of the main diatom bloom, allowing mechanisms that sustain continued diatom contributions to be examined. Diatom biomass was initially relatively high with biogenic silica concentrations up to 2.25 μmol Si L−1. A low initial silicic acid concentration of 0.1–0.3 μM imposed severe Si limitation of silica production and likely limited the diatom growth rate. Four storms over the next 3.5 weeks entrained silicic acid into the mixed layer, relieving growth limitation, but uptake limitation persisted. Silica production was modest and dominated by the >5.0 μm size fraction although specific rates were highest in the 0.6–5.0 μm size fraction over most of the cruise. Silica dissolution averaged 68% of silica production. The resupply of silicic acid via storm entrainment and silica dissolution supported a cumulative post‐bloom silica production that was 32% of that estimated during the main bloom event. Diatoms contributed significantly to new and to primary production after the initial bloom, possibly dominating both. Diatom contribution to organic‐carbon export was also significant at 40%–70%. Thus, diatoms can significantly contribute to regional biogeochemistry following initial silicic acid depletion, but that contribution relies on physical processes that resupply the nutrient to surface waters.

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Microbial Respiration in Contrasting Ocean Provinces via High-Frequency Optical Assays

Cohn

Stephens

Meyer

et al. 2023

Preprint

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Microbial respiration plays a pivotal role in the marine carbon cycle, influencing the fraction of fixed carbon that undergoes remineralization versus export to depth. Despite its importance, methodological constraints have led to an inadequate understanding of this process, especially in low-activity oligotrophic and mesopelagic regions. Here, we quantify respiration rates as low as 0.2 μmol O2 L-1 d-1 in contrasting ocean productivity provinces using optical oxygen sensors to identify size-fractionated respiration trends. At the low productivity North Pacific Ocean Station Papa, surface microbial respiration was relatively stable at 1.2 μmol O2 L-1 d-1. Below the surface there was a decoupling of respiration and bacterial production potentially driven by phytodetritus remineralization. Size-fractionated rates showed cells <5 μm contributed the most to Pacific respiration. At the North Atlantic Porcupine Abyssal Plain, the optode measurement frequency was drastically increased. Surface microbial respiration was higher (1.7 μmol O2 L-1 d-1) and decreased by 3-fold below the euphotic zone. The Atlantic filtered fraction contributions to total respiration shifted with the phytoplankton bloom evolution. The high resolution optode method used in the Atlantic is consistent with coinciding in vivo 2-para-(iodophenyl)-3(nitrophenyl)-5(phenyl) tetrazolium chloride respiratory stain measurements and historical site estimates. We estimate that 58% of gross primary production was respired at the Pacific site and 34% at the Atlantic site, demonstrating that the Atlantic had a higher carbon export potential. This study highlights the dynamic nature of respiration across vertical, temporal, and size-fractionated factors, emphasizing the need for sensitive, high-throughput techniques to better understand ocean ecosystem metabolism.

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Primary production dynamics during the decline phase of the North Atlantic annual spring bloom

Cited by 5 publications

References 60 publications

Microbial respiration in contrasting ocean provinces via high-frequency optode assays

Microbial respiration in contrasting ocean provinces via high-frequency optode assays

Physical Mechanisms Sustaining Silica Production Following the Demise of the Diatom Phase of the North Atlantic Spring Phytoplankton Bloom During EXPORTS

Microbial Respiration in Contrasting Ocean Provinces via High-Frequency Optical Assays

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