The phytoplankton community model, PROTECH, simulates algal growth and is sensitive to numerous environmental variables (temperature, depth, light, daylength, nutrient supply). This investigation examines the effects of altering, in turn, each of these variables upon the simulated algal growth. We compare these results with those predicted by a phytoplankton variation on Grime's C-S-R paradigm. Finally, it is concluded that PROTECH is a suitable tool for the exploration of community assembly in relation to the ecological theories of competition, succession and biodiversity.