SIZE PLASTICITY OF FRESH-WATER PHYTOPLANKTON - IMPLICATIONS FOR COMMUNITY STRUCTURE

A survey of 330 phytoplankton communities in Florida lakes shows the range of populations (i.e. from sparse to dense) developed by 63 phytoplankton genera to increase with increasing size plasticity of the genera. The average size of individuals within genera tended to increase as the 1/2 power of their biomass in the community, the strength and nature of these relationships depending on the potential for size plasticity of the genera. These patterns provide evidence of the important adaptative value of algal size and support the notion that algal biomass is an important vector constraining the structure of phytoplankton communities.