Our conceptual understanding of the role of heterotrophic bacteria in pelagic ecosystems and in ocean biogeochemical cycles is closely linked to our understanding of how their growth rate, abundance, and diversity is controlled. Here we discuss consequences of the simplifying assumption that there are only 5 potentially important interactions between heterotrophic bacteria and their biological and chemical environment.
Bacterial abundance is assumed to be controlled by protozoan predation in all cases.
For each class, we derive expressions describing bacterial carbon demand, and discuss the control of bacterial carbon demand, growth rate and diversity. For 2 classes of models, infectious viruses are shown to affect neither growth rate nor abundance of the steady state bacterial community. For all 4 classes of models, viruses are suggested to control diversity of the steady state bacterial community.