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Ecological Control of Subtropical Nutrient Concentrations
Jan 31st, 2010

Ecological Control of Subtropical Nutrient Concentrations

story by Helen Hill and Stephanie Dutkiewicz.

Figure 1: Multiple-Resource Experiment. (top) Emergent biogeographical provinces, defined by most dominant species, reminiscent of Longhurst (1995). (bottom) Biogeography of four major functional groups: (i) Diatom-analogs (red), (ii) other large phytoplankton (orange), (iii) <i>Prochlorococcus</i>-analogs (green), and (iv) other small phytoplankton (yellow-green).

Figure 1: Multiple-Resource Experiment. (top) Emergent biogeographical provinces, defined by most dominant species, reminiscent of Longhurst (1995). (bottom) Biogeography of four major functional groups: (i) Diatom-analogs (red), (ii) other large phytoplankton (orange), (iii)Prochlorococcus-analogs (green), and (iv) other small phytoplankton (yellow-green).

In this article we spotlight recent work by Darwin Project team members Stephanie Dutkiewicz, Mick Follows and Jason Bragg, who have been examining the utility of resource control theory to interpret the relationships between organisms and resources in a global coupled physical-biogeochemistry-ecosystem model built around MITgcm.

The team find that in regions of low seasonality, resource competition theory (Tilman, ‘77)  not only anticipates the competitive outcome amongst organisms but also provides a quantitative diagnostic of ecological control of nutrient concentrations. DFB’s sensitivity experiments clearly indicate control on the ambient nutrient by phytoplankton physiology as predicted by the theory. Read the rest of this entry »

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Ocean Ecosystems
Jun 18th, 2009

Population Competition in Action

story by Helen Hill

As the Darwin project begins to bear fruit we focus here on the work of recent doctoral graduate Fanny Monteiro who together with Mick Follows and Stephanie Dutkiewicz have been using the MITgcm to probe the behaviour of self-assembling phytoplankton communities within a global ocean circulation (Follows et al. 2007). Figure 1 summarises the core ideas behind the teams work: Within this, many tens of phytoplankton “types” are initialized, each one having a randomly assigned sensitivity to light, temperature and nutrient requirements. In Fanny’s work, she additionally initialised this model with populations of “diazotrophs” – organisms that can fix their own nitrogen, but with the trade-off of correspondingly slow growth and high iron to phosphorus requirements.

Figure 1. Illustration of the key components in the self-assembling phytoplankton community model. After some years of interaction, the fittest "types" persist and occupy distinct habitats.

Figure 1. Illustration of the key components in the self-assembling phytoplankton community model. After some years of interaction, the fittest "types" persist and occupy distinct habitats.

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