Hierarchical control of phytoplankton succession by physical factors

Abstract

The influence of physical factors on phytoplankton succession was assessed during an annual cycle in the St. Lawrence Estuary (Canada), where nutrients remain abundant throughout the whole year. Results demonstrate that the frequency of destabilization of the water column selects the growth rates of the cells, through nutrient conditions. Mean light intensity in the mixed layer determines the occurrence of non-motile forms such as diatoms, and temperature sets the conditions for optimal metabolic activity (flagellate numbers and succession of diatom species). This results in a conceptual model where stability conditions, mean light in the mixed layer and temperature hierarchically control phytoplankton succession.