A simulation study of the growth of benthic microalgae following the decline of a surface phytoplankton bloom

The West Florida continental shelf is an oligotrophic system for most of the year. An episodic chlorophyll plume has previously been observed in satellite imagery on the northern portion of the shelf during the spring months. The fate of the plume upon its decline in the late spring and early summer is unknown. Decreased chlorophyll levels and sustained nutrient stocks may be explained by sediment/water-column interactions, including the presence of benthic microalgae. A one-dimensional model, consisting of 16 state variables, is constructed to simulate the decline of a surface chlorophyll bloom in the northeastern Gulf of Mexico as measured during the Florida Shelf Lagrangian Experiment (FSLE). Results from a baseline simulation of two FSLE studies suggest that remineralized nutrients from the declining bloom are taken up by heterotrophic bacteria in the water-column and by benthic microalgae in the sediments. Perturbation experiments imply that low light levels, due to increased CDOM, do not have significant effects on the benthic microfloral community at mid-shelf locations.