Pond Boss Forums STOCKING A NEW POND Creating the food chain Plankton

One has to be careful when genralizing from graphs or a conclusion. The graph of phytoplankton growth curve above can be misleading because it does not provide what species were present as the temperature increases. Often in freshwater (FW) systems, it is the less than beneficial bluegreen algae (Cyanobacteria) are the most heat tolerant species. For most "wild" FW plankton communities normally as the temperature increases there is a shift in species composition which occurs at various points based on several variables such as day length & nutrient composition.
The graph alone also leads one to believe or asume that phytoplankton is a simple system comprised of one, a couple or a few species creating the nice 'smooth' data set. Rarely is that the case. What happens in my experience is as the temperature increases the species present change and above certain temperature levels or plateaus many drop out and at the end only a few or one specie is present at the highest temperatures on the graph - heat tolerant types. Sometimes those graphs are adapted from laboratory studies (growth cultures) where only one or two optimum species are used to create the data points and the graph nicely displayed the author's point.