onstration of succession regulation, or Acknowledgments

Any explanation of seasonal succession of phytoplankton communities should discuss why replaced species reappear, in roughly the same concentrations, in following years. A model of an annual cycle, representing two or more groups of phytoplankton but only one type each of nutrient and herbivore, can exhibit seasonal succession of two groups, and coexistence of three. It shows some of the features common to many instances of succession. Although the model’s physical environment repeats exactly from year to year, its plankton populations commonly oscillate with a period of 2 yr or longer. Models with a single, undifferentiated phytoplankton component may overestimate the predictability of plankton populations. Phytoplankton communities in oceans and lakes generally comprise different species at different times of year (e.g. Kalf