Sack Lunch Seminar (SLS)

Modeling the Coupling of Ecology and Biogeochemistry in the Present and Future
Ocean













We examine the interplay between ecology and biogeochemical cycles in the
context of a global three-dimensional ocean model where self-assembling
phytoplankton communities emerge from a wide set of potentially viable cell
types. The emergent community structures and ecological regimes vary across
different physical environments in the model ocean: Strongly seasonal,
high-nutrient regions are dominated by fast growing bloom specialists, while
stable, low-seasonality regions are dominated by organisms that can grow at low
nutrient concentrations. In the latter regions, the framework of resource
competition theory provides a useful qualitative and quantitative diagnostic
tool with which to interpret the outcome of competition between model organisms
in the more complex model, their regulation of the resource environment, and
the sensitivity of the system to changes in key physiological characteristics
of the cells. We use this "laboratory" to investigate the changes that may
result in a future changing climate. Our models suggest some subtle and
interesting interactions. In a warming world, reduced subtropical surface
nutrient concentrations are not directly caused by reduced supply but a
temperature driven increase in photo-autotroph growth rates.