Limnological characteristics of six subtropical lakes were monitored to determine the factors which regulate chlorophyll α concentrations and phytoplankton standing crops. Most physical chemical variables showed non-significant differences with depth but differences between lakes often were large. Phytoplankton blooms occurred throughout the year and there were marked differences between the hypereutrophic and mesotrophic lakes in chlorophyll α concentrations, standing stocks, and dominant species. Densities of total zooplankton and rotifers in the hypereutrophic lakes were 3- to 6-fold greater than in the mesotrophic lakes. Regression models for chlorophyll α and total phytoplankton cell volume were calculated for each lake and for all lakes combined, but R2 values and numbers of shared variables tended to be low indicating the need for additional variables and more frequent sampling.