Behavior of a simple plankton model with food-level acclimation by herbivores

Abstract. The North Atlantic spring bloom is one of the main events that lead to carbon export to the deep ocean and drive oceanic uptake of CO 2 from the atmosphere. Here we use a suite of physical, bio-optical and chemical measurements made during the 2008 spring bloom to optimize and compare three different models of biological carbon export. The observations are from a Lagrangian float that operated south of Iceland from early April to late June, and were calibrated with ship-based measurements. The simplest model is representative of typical NPZD models used for the North Atlantic, while the most complex model explicitly includes diatoms and the formation of fast sinking diatom aggregates and cysts under silicate limitation. We carried out a variational optimization and error analysis for the biological parameters of all three models, and compared their ability to replicate the observations. The observations were sufficient to constrain most phytoplankton-related model parameters to accuracies of better than 15 %. However, the lack of zooplankton observations leads to large uncertainties in model parameters for grazing. The simulated vertical carbon flux at 100 m depth is similar between models and agrees well with available observations, but at 600 m the simulated flux is larger by a factor of 2.5 to 4.5 for the model with diatom aggregation. While none of the models can be formally rejected based on their misfit with the available observations, the model that includes export by diatom aggregation has a statistically significant better fit to the observations and more accurately represents the mechanisms and timing of carbon export based on observations not included in the optimization. Thus models that accurately simulate the upper 100 m do not necessarily accurately simulate export to deeper depths.

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“…Zooplankton grazing is parameterized using a modified Ivlev equation (Franks et al, 1986) and depends on small phytoplankton concentration…”

Section: Model Descriptionmentioning

confidence: 99%

Optimizing models of the North Atlantic spring bloom using physical, chemical and bio-optical observations from a Lagrangian float

et al. 2011

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“…In the last two decades, numerous plankton models with instantaneous nutrient recycling have been proposed (see Busenberg et al, 1990;DeAngelis et al, 1989;Evan & Parslow, 1985;Fasham, 1993;Fasham et al, 1990;Franks et al, 1986;Henderson & Steele, 1995;Nisbet & Gurney, 1976;Nisbet et al, 1983;Ruan, 1993;Steele & Henderson, 1981Sarmiento et al, 1993;Truscott & Brindley, 1994;Wroblewski et al 1988). In 1995, Beretta et al and Ruan & Wolkowicz (1995) simultaneously proposed a plankton-nutrient model with delayed nutrient recycling.…”

Section: Introductionmentioning

confidence: 99%

Oscillations in Plankton Models with Nutrient Recycling

Ruan

2001

Journal of Theoretical Biology

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Plankton}nutrient interaction models with both instantaneous and delayed nutrient recycling are considered. The system consists of three components: autotrophic phytoplankton, herbivorous zooplankton and dissolved limiting nutrient. Local stability of the equilibria is analysed. It is shown that the positive equilibrium loses its stability when the nutrient input concentration passes through a critical value and the Hopf bifurcation occurs that induces oscillations of the populations. Numerical simulations are carried out to illustrate the obtained results.

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“…Conceptually the NPZ model is slightly different from other three state NPZ models in the literature, e.g. Franks et al (1986); Fasham et al (1990); Edwards & Brindley (1996), in that a mechanistic approach has been adopted in the derivation in some of the terms (see model description). An important addition for this work is the inclusion of a non-uniform flux of nutrients into the bottom of the surface mixed layer.…”

Section: Phytoplankton Patchiness Induced By Langmuir Circulationsmentioning

confidence: 99%

Large-eddy simulation of subsurface phytoplankton dynamics: an optimum condition for chlorophyll patchiness induced by Langmuir circulations

Brereton¹,

Siddons²,

Lewis³

2018

Mar. Ecol. Prog. Ser.

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Phytoplankton patchiness occurs on a plethora of spatial and temporal scales which can be extremely patchy in both horizontal and vertical directions. This patchiness directly affects the dynamics of the overall bloom, so understanding the mechanisms for patchiness to occur on each scale is therefore integral to the understanding of plankton bloom dynamics as a whole. This modelling study aims to introduce a mechanism for patch formations, which has previously had very little exposure, but is ubiquitous to the oceanic mixed layer -patchiness induced by the interaction between nutrient upwelling and Langmuir circulations.

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Behavior of a simple plankton model with food-level acclimation by herbivores

Cited by 202 publications

References 22 publications

Optimizing models of the North Atlantic spring bloom using physical, chemical and bio-optical observations from a Lagrangian float

Optimizing models of the North Atlantic spring bloom using physical, chemical and bio-optical observations from a Lagrangian float

Oscillations in Plankton Models with Nutrient Recycling

Large-eddy simulation of subsurface phytoplankton dynamics: an optimum condition for chlorophyll patchiness induced by Langmuir circulations

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