Ocean plankton populations as excitable media

Truscott, James E.; Brindley, J.

doi:10.1007/bf02458277

Cited by 167 publications

(112 citation statements)

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“…This is the hallmark of an excitable system. Truscott & Brindley (1994) investigated a two-component phytoplankton-zooplankton (PZ) model that has the characteristics of an excitable system whose excitability is robust over a realistic parameter range. Normally, however, a large driving perturbation is required to initiate the bloom in general for an excitable system.…”

Section: Introductionmentioning

confidence: 99%

Plankton blooms induced by turbulent flows

Reigada

Hillary

Bees

et al. 2003

Proc. R. Soc. Lond. B

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Plankton play an important role in the ecology of the ocean and the climate because of their participation in the global carbon cycle at the base of the food chain. However, damaging plankton blooms can sometimes occur and are initially characterized by sudden transient increases in the phytoplankton population. They are thought to be driven by several effects, such as seasonal variations in temperature and salinity, and nutrient mixing. Furthermore, phytoplankton and zooplankton have different buoyancy properties, leading to a differential response in turbulent environments. In this paper, we investigate this effect in a model of advected plankton dynamics. We find that, over a range of parameter values, flows of marine species subjected to inertial/viscous forces naturally lead to patchiness and, in turn, periodically sustained plankton blooms.

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Section: Introductionmentioning

confidence: 99%

Plankton blooms induced by turbulent flows

Reigada

Hillary

Bees

et al. 2003

Proc. R. Soc. Lond. B

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“…All three components are advected by a two-dimensional flow, v(r, t), obtained from a so-called seeded eddy model [Abraham, 1998], and diffusive terms represent the effect of small-scale mixing (k = 4 m 2 s À1 ). The biological terms on the right-hand sides describe logistic growth of phytoplankton, grazing by zooplankton and growth and mortality for zooplankton, following [Truscott and Brindley, 1994a;Steele and Henderson, 1992]. [5] The third equation describes the dispersal of the relative iron anomaly, where loss terms arising from sinking and uptake by phytoplankton have been neglected, for simplicity, as it turns out that they are not important for the long term behavior of the model.…”

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confidence: 99%

“…[2] Truscott and Brindley [Truscott and Brindley, 1994a] suggested that plankton blooms might be explained by the excitability of the dynamical system describing biological interactions in the plankton ecosystem. The characteristic feature of excitable systems [Meron, 1992] is that perturbations exceeding a certain threshold can induce a temporary large deviation from the equilibrium state.…”

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confidence: 99%

“…The biological terms on the right-hand sides describe logistic growth of phytoplankton, grazing by zooplankton and growth and mortality for zooplankton, following [Truscott and Brindley, 1994a;Steele and Henderson, 1992]. The parameter values are based on [Truscott and Brindley, 1994a], adjusted to the SOIREE situation so that the equilibrium state of the homogeneous system is consistent with the observations (r 0 = 0. [5] The third equation describes the dispersal of the relative iron anomaly, where loss terms arising from sinking and uptake by phytoplankton have been neglected, for simplicity, as it turns out that they are not important for the long term behavior of the model.…”

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confidence: 99%

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Ocean fertilization experiments may initiate a large scale phytoplankton bloom

Neufeld

Haynes

Garçon

et al. 2002

Geophysical Research Letters

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[1] Oceanic plankton plays an important role in the marine food chain and through its significant contribution to the global carbon cycle can also influence the climate. Plankton bloom is a sudden rapid increase of the population. It occurs naturally in the North Atlantic as a result of seasonal changes. Ocean fertilization experiments have shown that supply of iron, an important trace element, can trigger a phytoplankton bloom in oceanic regions with low natural phytoplankton density. Here we use a simple mathematical model of the combined effects of stirring by ocean eddies and plankton evolution to consider the impact of a transient local perturbation, e.g., in the form of iron enrichment as in recent 'ocean fertilization' experiments. The model not only explains aspects of the bloom observed in such experiments but predicts the unexpected outcome of a large scale bloom that in its extent could be comparable to the spring bloom in the North Atlantic. [Truscott and Brindley, 1994a] suggested that plankton blooms might be explained by the excitability of the dynamical system describing biological interactions in the plankton ecosystem. The characteristic feature of excitable systems [Meron, 1992] is that perturbations exceeding a certain threshold can induce a temporary large deviation from the equilibrium state. The plankton bloom produced artificially by iron fertilization experiments has been shown to be consistent with excitable system behaviour [Pitchford and Brindley, 1999]. However, previous work has considered only the spatially homogeneous situation, and need not be relevant to the iron fertilization experiments, in which localised perturbations produce a localised bloom that is subsequently strongly affected by stirring by mesoscale ocean eddies.[3] The role of stirring has been recognised and investigated in the context of the SOIREE experiment [Boyd et al., 2000;Abraham et al., 2000] and the spatial characteristics of the bloom filament was found to be similar to that seen in tracer release experiments [Sundermeyer and Price, 1998], in having a roughly constant width and exponentially increasing length. However, the biological evolution in this analysis was modelled by a simple linear growth rate, which cannot be adequate for predicting the long term behavior of the bloom when nonlinearities, e.g. interactions with other species, become important.[4] Here we consider a, perhaps minimal, model that unifies the two approaches described above by taking into account spatial distribution, stirring and non-linear interactions between biological components. The model equations arewhere P, Z represent the phytoplankton and zooplankton concentration (in nitrogen currency) and F is the deviation of the iron concentration from the original homogeneous background. All three components are advected by a two-dimensional flow, v(r, t), obtained from a so-called seeded eddy model [Abraham, 1998], and diffusive terms represent the effect of small-scale mixing (k = 4 m 2 s À1 ). The biological terms on the right-han...

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“…Some models (e.g. 'red tide' models) simply do not 'work' when we replace Holling type III with Holling type II or I [35].…”

Section: Introductionmentioning

confidence: 99%

Patterns of Zooplankton Functional Response in Communities with Vertical Heterogeneity: a Model Study

Морозов

Арашкевич

2008

Math. Model. Nat. Phenom.

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Abstract. Parameterization of zooplankton functional response is crucial for constructing plankton models. Theoretical studies predict enhancing of system stability in case the response is of sigmoid type. Experiments on feeding in laboratories tell us in favor of non-sigmoid types for most herbivorous zooplankton species. However, recent field observations show that the overall functional response of zooplankton in the whole euphotic zone can exhibit a sigmoid behavior even when the response for the same species in laboratory mesocosms is non-sigmoid. Here we propose a simple model explaining the observed alterations of functional response. We divide the euphotic zone into a number of layers and take into account the food-dependent migration of zooplankton. In each layer, the functional response (local response) is suggested to be non-sigmoid. We show that the overall response of zooplankton exhibits different behavior compared to the patterns of the local response. In particular, the model predicts emergence of a sigmoid type as a result of zooplankton accumulation and feeding in layers with high phytoplankton density. We show the importance of light attenuation by phytoplankton on the alteration of functional response. The modelling results allow us to hypothesize that the sigmoid functional response in real communities should emerge more often than it was suggested earlier based only on experimental studies on zooplankton feeding.

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Ocean plankton populations as excitable media

Cited by 167 publications

References 10 publications

Plankton blooms induced by turbulent flows

Plankton blooms induced by turbulent flows

Ocean fertilization experiments may initiate a large scale phytoplankton bloom

Patterns of Zooplankton Functional Response in Communities with Vertical Heterogeneity: a Model Study

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