As in the other "free-floating" exhcanges portrayed in the model (salt, nutrients, sediments, etc.), phytoplankton is heavily dependent on the speed of the currents to flux through the bay. The fraction of phytoplankton that moves out of the cell is proportionate to the fraction of surface water that moves out of the cell to total amount of water in the cell. Water movement is calculated in the global input sector.
Phytoplankton primary production is limited by light, nutrients, and water temperature. Phytoplankton biomass is lost through respiration, consumption, and mortality.
* Note: only spatial movement to the north is portrayed here for the sake of simplicity. Movement to the south, east, and west is calculated in the same manner.