A Regional, Early Spring Bloom of <i>Phaeocystis pouchetii</i> on the New England Continental Shelf

Smith, Walker O; Zhang, Weifeng G.; Hirzel, Andrew J.; Stanley, Rachel; Meyer, Meredith G.; Sosik, Heidi M.; Alatalo, Philip; Oliver, H. R.; Sandwith, Zoe O.; Crockford, E. Taylor; Peacock, Emily E.; Mehta, Arshia; McGillicuddy, Dennis J.

doi:10.1029/2020jc016856

Cited by 16 publications

(10 citation statements)

References 69 publications

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“…The VPR was towed at 10 knots (5.1 m s −1 ), undulating between 5 and up to 100 m with a vertical velocity of approximately 1 m s −1 . Net community production (NCP) integrated over the mixed layer was calculated for the VPR transect from O 2 /Ar measured continuously (seconds‐to‐minutes) by an Equilibrator Inlet Mass Spectrometer (EIMS) from the ship's underway system (intake depth = 2.1 m; Smith et al., 2021). We present data from VPR Tow 1 on 18 April 2018, near the beginning of the cruise.…”

Section: Methodsmentioning

confidence: 99%

Ephemeral Surface Chlorophyll Enhancement at the New England Shelf Break Driven by Ekman Restratification

et al. 2022

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The Mid‐Atlantic Bight (MAB) hosts a large and productive marine ecosystem supported by high phytoplankton concentrations. Enhanced surface chlorophyll concentrations at the MAB shelf‐break front have been detected in synoptic measurements, yet this feature is not present in seasonal means. To understand why, we assess the conditions associated with enhanced surface chlorophyll at the shelf break. We employ in‐situ and remote sensing data, and a 2‐dimensional model to show that Ekman restratification driven by upfront winds drives ephemerally enhanced chlorophyll concentrations at the shelf‐break front in spring. Using 8‐day composite satellite‐measured surface chlorophyll concentration data from 2003–2020, we constructed a daily running mean (DRM) climatology of the cross‐shelf chlorophyll distribution for the northern MAB region. While the frontal enhancement of chlorophyll is apparent in the DRM climatology, it is not captured in the seasonal climatology due to its short duration of less than a week. In‐situ measurements of the frontal chlorophyll enhancement reveal that chlorophyll is highest in spring when the shelf‐break front slumps offshore from its steep wintertime position causing restratification in the upper part of the water column. Several restratification mechanisms are possible, but the first day of enhanced chlorophyll at the shelf break corresponds to increasing upfront winds, suggesting that the frontal restratification is driven by offshore Ekman transport of the shelf water over the denser slope water. The 2‐dimensional model shows that upfront winds can indeed drive Ekman restratification and alleviate light limitation of phytoplankton growth at the shelf‐break front.

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Section: Methodsmentioning

confidence: 99%

Ephemeral Surface Chlorophyll Enhancement at the New England Shelf Break Driven by Ekman Restratification

et al. 2022

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“…Productivity was also measured using 14 C-uptake (Smith et al, 2000(Smith et al, , 2021. Briefly, samples were collected from known isolumes and placed into sterile 280 mL Qorpak bottles to which ca.…”

Section: Methodsmentioning

confidence: 99%

“…Photoinhibition effects were included using the relationship determined by Behrenfeld and Falkowski (1997b). Daily productivity was derived by integrating the rates through the 1% isolume depth (Oliver et al, 2021;Smith et al, 2021). All variables of both models are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…From April 17 to April 24, offshore movement of the front (the position of the 34.5 isohaline) was consistent with a westward motion of the front oriented in a WNW-ESE direction. The spring inshore bloom was at times dominated by Phaeocystis pouchetii, but the chlorophyll offshore was dominated by diatoms (Smith et al, 2021). Nitrate concentrations exceeded 5 µM inshore but less in offshore waters.…”

Section: Depth Of Euphotic Zone Z Eu Mmentioning

confidence: 95%

“…A second, related method is the vertically resolved method of estimating productivity, which again uses temperature, chlorophyll concentrations, and PAR in combination with a photosynthesis model. This allows for the primary productivity to be estimated throughout the water column at discrete depths and then integrated to give daily productivity estimates, and can be applied to different locations where highly resolved chlorophyll and temperature data are available (e.g., from closely spaced CTD measurements; Oliver et al, 2021;Smith et al, 2021). Such a method allows for the incorporation of small-scale features (e.g., narrow chlorophyll maxima) to be included in estimates of integrated productivity (Oliver et al, 2021), as well as to more reliably account for vertical temperature changes.…”

Section: Introductionmentioning

confidence: 99%

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Primary Productivity in the Mid-Atlantic Bight: Is the Shelf Break a Location of Enhanced Productivity?

Smith

2022

Front. Mar. Sci.

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Estimates of primary production represent the input of carbon into food webs, as well as the initial step in the biological pump. For the past 60 years, much of the productivity information has been obtained using measurements of 14C-bicarbonate removal during simulated in situ incubations. However, such measurements often do not reflect the complexity of the environment, and also suffer from uncertainties, biases and limitations. A vertically resolved bio-optical model has been used to estimate productivity based on profiles commonly assessed in oceanographic investigations, but comparisons with simultaneous measurements of 14C-uptake are limited. We conducted three cruises off the coast of New England that included sampling continental shelf waters, the shelf-break region, and deeper waters at scales of 7 km, all of which had productivity estimated by a vertically resolved productivity model as well as by traditional 14C-uptake measurements using simulated in situ techniques. We found that the vertically resolved bio-optical model gave results that appear to be more robust and resolved productivity at smaller vertical and horizontal scales, and seem less biased by some of the uncertainties in 14C-uptake measurements. Both estimates suggest that the New England waters are highly productive due to a variety of biological and physical processes occurring at different times of the year, but there was no consistent stimulation at the shelf break over the time scales of these estimates.

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Spring Phytoplankton Distributions and Primary Productivity in Waters off Northern Norway

Smith

Meng

Basedow³

2022

Preprint

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Phytoplankton distributions and primary productivity were assessed off the northern coast of Norway in spring. Biomass and productivity were greatest off the continental shelf during the period of observations. * A satellite climatology showed that blooms usually form on the continental shelf first, and spread to deeper waters from 2-4 weeks after the shelf bloom. * The Calanus finmarchicus population had the potential for removing substantial amounts of chlorophyll each day, but phytoplankton vertical distributions were controlled by passive sinking.

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A Regional, Early Spring Bloom of Phaeocystis pouchetii on the New England Continental Shelf

Cited by 16 publications

References 69 publications

Ephemeral Surface Chlorophyll Enhancement at the New England Shelf Break Driven by Ekman Restratification

Ephemeral Surface Chlorophyll Enhancement at the New England Shelf Break Driven by Ekman Restratification

Primary Productivity in the Mid-Atlantic Bight: Is the Shelf Break a Location of Enhanced Productivity?

Spring Phytoplankton Distributions and Primary Productivity in Waters off Northern Norway

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