The North Atlantic Spring Phytoplankton Bloom and Sverdrup's Critical Depth Hypothesis

Siegel, David A.; Doney, Scott C.; Yoder, James A.

doi:10.1126/science.1069174

Cited by 481 publications

(539 citation statements)

References 24 publications

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“…Near the offshore boundary of the Middle Atlantic Bight, high levels of winter chlorophyll may reflect this region's similarity to subtropical conditions (i.e. light levels, winds), since the North Atlantic subtropical gyre is characterized by an OctoberFebruary chlorophyll maximum (Henson et al, 2009;Siegel et al, 2002). Hence, in some years, blooms in the Middle Atlantic Bight were detected with start dates as early as February.…”

Section: Discussionmentioning

confidence: 99%

Spring bloom dynamics and zooplankton biomass response on the US Northeast Continental Shelf

Friedland

Leaf

Kane

et al. 2015

Continental Shelf Research

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a b s t r a c tThe spring phytoplankton bloom on the US Northeast Continental Shelf is a feature of the ecosystem production cycle that varies annually in timing, spatial extent, and magnitude. To quantify this variability, we analyzed remotely-sensed ocean color data at two spatial scales, one based on ecologically defined sub-units of the ecosystem (production units) and the other on a regular grid (0.5°). Five units were defined: Gulf of Maine East and West, Georges Bank, and Middle Atlantic Bight North and South. The units averaged 47 Â 10 3 km 2 in size. The initiation and termination of the spring bloom were determined using change-point analysis with constraints on what was identified as a bloom based on climatological bloom patterns. A discrete spring bloom was detected in most years over much of the western Gulf of Maine production unit. However, bloom frequency declined in the eastern Gulf of Maine and transitioned to frequencies as low as 50% along the southern flank of the Georges Bank production unit. Detectable spring blooms were episodic in the Middle Atlantic Bight production units. In the western Gulf of Maine, bloom duration was inversely related to bloom start day; thus, early blooms tended to be longer lasting and larger magnitude blooms. We view this as a phenological mismatch between bloom timing and the "top-down" grazing pressure that terminates a bloom. Estimates of secondary production were available from plankton surveys that provided spring indices of zooplankton biovolume. Winter chlorophyll biomass had little effect on spring zooplankton biovolume, whereas spring chlorophyll biomass had mixed effects on biovolume. There was evidence of a "bottom up" response seen on Georges Bank where spring zooplankton biovolume was positively correlated with the concentration of chlorophyll. However, in the western Gulf of Maine, biovolume was uncorrelated with chlorophyll concentration, but was positively correlated with bloom start and negatively correlated with magnitude. This observation is consistent with both a "top-down" mechanism of control of the bloom and a "bottom-up" effect of bloom timing on zooplankton grazing. Our inability to form a consistent model of these relationships across adjacent systems underscores the need for further research.Published by Elsevier Ltd.

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Section: Discussionmentioning

confidence: 99%

Spring bloom dynamics and zooplankton biomass response on the US Northeast Continental Shelf

Friedland

Leaf

Kane

et al. 2015

Continental Shelf Research

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“…Recruitment of copepods, the most abundant mezozooplankton in the region, depends on the supply of food (Head et al, 2000). Interestingly, while the general pattern of bloom timing in the North Atlantic tends to be earlier at lower latitudes and later at higher latitudes (Siegel et al, 2002), this pattern is reversed within the Labrador Sea (Head et al, 2000). An early explanation of the reversal was offered by Head et al (2000), that ice melt from icebergs in the north Labrador Sea resulted in high stratification.…”

Section: Introductionmentioning

confidence: 99%

Physical controls and interannual variability of the Labrador Sea spring phytoplankton bloom in distinct regions

Frajka‐Williams

Rhines

2010

Deep Sea Research Part I: Oceanographic Research Papers

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We investigated the variability of the spring phytoplankton bloom in the Labrador Sea, dividing into distinct biogeographical zones, then analyzing the relationship between the bloom and physical forcings. The spring phytoplankton bloom in the north Labrador Sea varied in intensity by a factor of 4 and in timing of onset by 3 weeks over the 11-year record from SeaWiFS satellite ocean chlorophyll, 1998-2008. This north bloom (north of 60 • N and west of the Labrador shelves) is earliest and most intense, owing in part to the offshore-directed freshwater stratification from the West Greenland Current. On interannual timescales, significant correlations were found between the north bloom intensity and ocean processes, namely offshore advection, eddy activity and runoff from Greenland. In contrast, the central Labrador Sea is later and weaker, and only a correlation between the bloom timing and irradiance was found. As the subpolar gyre shifts in strength and shape, freshwater outflow from the Arctic and Greenland changes, we may expect further changes in the biological response as indicated by these relationships.

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“…Due to its global scale monitoring over several decades (e.g., Siegel et al 2002;Carr et al 2006), CHL a consists in a usefull indicator for assessing skill of ocean biogeochelical models. Generally, models roughly agree with large-scale observed patterns (R * 0.4, Table 3).…”

Section: Cfc11 and Cfc12 Distributionmentioning

confidence: 99%

“…The atmospheric and land components use the same regular horizontal grid with 96 9 96 points, representing a resolution of 3.6°9 1.8°, while the atmosphere has 39 vertical levels. The INCA (INteraction between Chemistry and Aerosol, e.g., Schulz 2007 andSzopa et al 2012) model is used to simulate tropospheric greenhouse gases and aerosol concentrations, while stratospheric ozone is modeled by REPROBUS (Reactive Processes Ruling the Ozone Budget in the Stratosphere, Lefevre et al 1994Lefevre et al , 1998.…”

Section: Ipsl-cm5a-lrmentioning

confidence: 99%

Skill assessment of three earth system models with common marine biogeochemistry

et al. 2012

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We have assessed the ability of a common ocean biogeochemical model, PISCES, to match relevant modern data fields across a range of ocean circulation fields from three distinct Earth system models: IPSL-CM4-LOOP, IPSL-CM5A-LR and CNRM-CM5.1. The first of these Earth system models has contributed to the IPCC 4th assessment report, while the latter two are contributing to the ongoing IPCC 5th assessment report. These models differ with respect to their atmospheric component, ocean subgrid-scale physics and resolution. The simulated vertical distribution of biogeochemical tracers suffer from biases in ocean circulation and a poor representation of the sinking fluxes of matter. Nevertheless, differences between upper and deep ocean model skills significantly point to changes in the underlying model representations of ocean circulation. IPSL-CM5A-LR and CNRM-CM5.1 poorly represent deep-ocean circulation compared to IPSL-CM4-LOOP degrading the vertical distribution of biogeochemical tracers. However, their representations of surface wind, wind stress, mixed-layer depth and geostrophic circulations (e.g., Antarctic Circumpolar Current) have been improved compared to IPSL-CM4-LOOP. These improvements result in a better representation of large-scale structure of biogeochemical fields in the upper ocean. In particular, a deepening of 20-40 m of the summer mixed-layer depth allows to capture the 0-0.5 lgChl L -1 concentrations class of surface chlorophyll in the Southern Ocean. Further improvements in the representation of the ocean mixedlayer and deep-ocean ventilation are needed for the next generations of models development to better simulate marine biogeochemistry. In order to better constrain ocean dynamics, we suggest that biogeochemical or passive tracer modules should be used routinely for both model development and model intercomparisons.

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The North Atlantic Spring Phytoplankton Bloom and Sverdrup's Critical Depth Hypothesis

Cited by 481 publications

References 24 publications

Spring bloom dynamics and zooplankton biomass response on the US Northeast Continental Shelf

Spring bloom dynamics and zooplankton biomass response on the US Northeast Continental Shelf

Physical controls and interannual variability of the Labrador Sea spring phytoplankton bloom in distinct regions

Skill assessment of three earth system models with common marine biogeochemistry

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