Mesozooplankton community characteristics in the NE subarctic Pacific

Goldblatt, Robert H.; Mackas, David L.; Lewis, A.G.

doi:10.1016/s0967-0645(99)00078-8

Cited by 70 publications

(38 citation statements)

References 34 publications

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“…There are some difficulties in trying to predict export flux using a single model simulation for two different months. In May, OSP is characterized by zooplankton transforming particles immediately below the euphotic zone (Dagg 1993) and low diel vertical migration (Goldblatt et al 1999). Significantly, in August at OSP, the ontogenetic migration to depth of the neocalanoid copepods has taken place, and there is evidence of more diel vertical migration, compared to May, by relatively small copepods (Goldblatt et al 1999).…”

Section: Discussionmentioning

confidence: 99%

“…In May, OSP is characterized by zooplankton transforming particles immediately below the euphotic zone (Dagg 1993) and low diel vertical migration (Goldblatt et al 1999). Significantly, in August at OSP, the ontogenetic migration to depth of the neocalanoid copepods has taken place, and there is evidence of more diel vertical migration, compared to May, by relatively small copepods (Goldblatt et al 1999). However, the ratios of the observed POC flux at the euphotic zone to 100 m below are very similar in both months ( Table 5), suggesting that other particle-transformation processes must be important.…”

Section: Discussionmentioning

confidence: 99%

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Shedding light on processes that control particle export and flux attenuation in the twilight zone of the open ocean

Buesseler

Boyd

2009

Limnology & Oceanography

427

529

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Pelagic food webs drive a flux of .10 310 12 kg C yr 21 that exits surface waters, mostly via sinking particles through the ocean's ''biological pump.'' Much of this particle flux is remineralized in the poorly studied waters of the twilight zone, i.e., the layer underlying the euphotic zone and extending to 1000 m. We present a reanalysis of selected upper-ocean studies of particulate organic carbon (POC) flux and relate these observations to a simple one-dimensional biological model to shed light on twilight zone processes. The ecosystem model first predicts particle flux from the base of the euphotic zone, and then its attenuation below based on transformations by heterotrophic bacteria and zooplankton, and active downward transport of surface-derived particles by zooplankton. Observations and simulations both suggest that future sampling strategies for the twilight zone should take regional variability of the euphotic zone depth (Ez) into account. In addition, conventional curvefitting of particle flux data (i.e., power law or exponential) skews our interpretation of twilight zone processes. To overcome these artifacts, we introduce two new terms: the Ez-ratio (POC flux at Ez relative to net primary production [NPP]) and T 100 (the ratio of POC flux 100 m below Ez to POC flux at Ez). A comparison of NPP, Ezratios, and T 100 provides a new set of metrics to classify the ocean into different regimes, representing high and low surface export and subsurface flux attenuation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Shedding light on processes that control particle export and flux attenuation in the twilight zone of the open ocean

Buesseler

Boyd

2009

Limnology & Oceanography

427

529

View full text Add to dashboard Cite

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“…1). No sampling occurred between 1981 and 1995 (Goldblatt et al 1999) and SUPER Program data from May 1988 (Miller 1993), although the timing of this latter survey was such that only N. flemingeri copepodites were sufficiently abundant. TTs also took place in June 1997, but by this later time, C5 copepodites already made up more than 50% of the population, as did N. flemingeri copepodites in both years.…”

Section: Discussionmentioning

confidence: 99%

“…the duration of the period of high biomass). Mackas et al 1993, Miller 1993, Goldblatt et al 1999. Although contemporaneous depth-stratified and CPR sampling was too limited for direct comparison, these data do enable us to compare the depth preferences of the different copepodite stages.…”

Section: Methodsmentioning

confidence: 99%

Shortened duration of the annual Neocalanus plumchrus biomass peak in the Northeast Pacific

Batten¹,

Mackas²

2009

Mar. Ecol. Prog. Ser.

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The calanoid copepod Neocalanus plumchrus (Marukawa) is a dominant member of the spring mesozooplankton in the subarctic North Pacific and Bering Sea. Previous studies have shown interdecadal and latitudinal variation in seasonal developmental timing, with peak biomass occurring earlier in years and places with warmer upper ocean temperatures. Because N. plumchrus normally has a single dominant annual cohort, its seasonal timing can be indexed from measurements of total population biomass or by following progressive changes in stage composition. Early studies empirically found that peak upper ocean biomass occurred when about half of the pre-dormant population had reached copepodite stage 5 (C5). However, more recent comparisons derived from recent Continuous Plankton Recorder (CPR) data now show peak biomass when a larger fraction (> 80%) of the population is at C5. CPR samples the surface 10 to 15 m, but comparisons to depth-resolved BIONESS data show that this discrepancy is not an artefact of sampling depth. Other causes are either a prolongation of duration of pre-dormant C5 or a narrowing of the age range making up the annual cohort. We assessed changes in cohort width using a modification of Greve's cumulative percentile method, and found that average cohort widths in the Alaska Gyre were significantly narrower in

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“…time scales for changes in Z 2 biomass are much longer than for phytoplankton and microzooplankton, and thus Z 2 is specified at the maximum value of the observed annual cycle (Goldblatt et al, 1999) in order to simulate summer conditions. The only nutrient explicitly modeled, and so the only potentially limiting nutrient in the model, is nitrogen (N ).…”

Section: Modelmentioning

confidence: 99%

Perturbation dynamics of a planktonic ecosystem

Healey¹,

Monahan²,

Ianson³

2009

J Mar Res

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Planktonic ecosystems provide a key mechanism for the transfer of CO 2 from the atmosphere to the deep ocean via the so-called "biological pump".Mathematical models of these ecosystems have been used to predict CO 2 uptake in surface waters, and more recently have been embedded in global climate models. While the equilibrium properties of these models are well studied, less attention has been paid to their response to external perturbations, despite the fact that, as a result of the variability of environmental forcing, such ecosystems are rarely, if ever, in equilibrium. Human induced perturbations to these ecosystems, namely the addition of limiting nutrients (e.g. iron) to areas where nitrate is plentiful to accelerate the biological pump, have been proposed as a solution to reduce atmospheric CO 2 . In this study, linear theory is used to determine the structure of initially "unit-norm" perturbations to state variables of a five state variable ecosystem model in steady state, describing Ocean Station P (50 • N 145 • W) in summer, that optimize either instantaneous export flux of organic matter at fixed times or integrated export as the ecosystem relaxes towards equilibrium. A common feature in the optimization experiments for both instantaneous and integrated flux is the synchronization of the oscillatory behavior between two state variables. Because of these oscillations, there is an indirect contribution to the export flux that is non-intuitive. For all perturbations, it is found that the flux to higher trophic levels is the primary contributor to export flux, and, contrary to expectations, the contribution of aggregation is negligible.

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Mesozooplankton community characteristics in the NE subarctic Pacific

Cited by 70 publications

References 34 publications

Shedding light on processes that control particle export and flux attenuation in the twilight zone of the open ocean

Shedding light on processes that control particle export and flux attenuation in the twilight zone of the open ocean

Shortened duration of the annual Neocalanus plumchrus biomass peak in the Northeast Pacific

Perturbation dynamics of a planktonic ecosystem

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