Competition of two suspension-feeding protozoan populations for a growing bacterial population in continuous culture.

Mathematical studies for ecosystems involving 2 predators competing for a growing prey population have shown that the 2 competitors can coexist in a state of sustained oscillations for a range of values of the system parameters. For the case of 1 suspension-feeding protozoan population, recent experimental observations suggest that the predator-prey interaction is complicated by the ability of the bacteria to grow on products produced by the lysis of protozoan cells. This situation is studied here for the case where 2 suspension-feeding protozoan populations compete for a growing bacterial population in a chemostat. Computer simulations show that the 2 protozoan populations can coexist over a range of the operating parameters. Some necessary conditions for coexistence are presented as are some speculations regarding the possible physical explanations of results.