A New Mechanistic Model of Aggregation and Particle Export Flux Using Multiple Particle Types

The particulate material sinking out of the surface ocean is a heterogeneous mixture of fecal pellets, aggregates, and other biological detritus. The relative magnitudes of these different components vary spatially and temporally, and the different physical properties of these components result in different particle sinking speeds, remineralization rates, and fates of the sinking material. With a few notable exceptions, detailed size-spectra models of aggregation most often consider one type consider particles to be homogeneous. I present initial results from a new detailed, low dimension, size resolved, mechanistic model for particle production, aggregation, and settling that follows the evolution of size distributions of aggregates, fecal pellets, and other forms of sinking detritus over time. The model is coupled to a simple food web model with two size classes of phytoplankton and zooplankton, and I use this to explore how changes in community structure affect changes in the flux of particulate material sinking out of the surface waters.