Sack Lunch Seminar (SLS)

Nutrients, grazing and the size-based biogeography of marine ecosystems


Direct observations along the Atlantic Meridional Transect, together with satellite-derived estimates, suggest that the large-scale marine ecosystem is characterised by a ubiquitous population of small phytoplankton, with regions of high biomass occurring through the superposition of larger phytoplankton size-classes. The pattern is captured by the complex ecosystem model, which itself remains consistent with analytical solutions to a much simpler theoretical model.

The hierarchy of theory, numerical model and observations supports the idea that (with notable exceptions) grazing places a limit on the amount of phytoplankton biomass within each size-class, while the nutrient supply dictates the number of size classes - and hence the total biomass - in the system.