Phytoplankton accumulation in Langmuir cells

We investigate the distribution of phytoplankton in Langmuir circulations, under various assumptions about the motion of the water and of phytoplankton through the water. The details of water movement appear to be relatively unimportant compared to the details of phytoplankton movement: Stommel's analysis of a very simple model is easily extended to more realistic descriptions of Langmuir circulation, but it breaks down if plankton velocities are not constant. We discuss some possible ecological consequences, especially concerning red tides.