CROWDING AND LIGHT LIMITATION AFFECT PHYTOPLANKTON COMPETITION FOR NITROGEN
Abstract
We consider a chemostat model of phytoplankton competing for nitrogen taking into account effects of both intra- and interspecific crowding and the light limitation. We consider crowding as an additive density-dependent mortality rate. Crowding effects may be classified into intra- and interspecific crowding depending on whether the additional mortality is caused by the same or alternate species.
We analyze the existence and local and global stability of single species and coexistence equilibria using the linearization and stability method of Lyapunov. We present a numerical example illustrating the fact that the crowding effects may lead to the bistable coexistence of two phytoplankton species. We demonstrate that the crowding effects and the light limitation affect the outcome of exploitative competition for a single resource and promote coexistence. We also show that while the crowding has a stabilizing effect on phytoplankton community, the light limitation may destabilize the system and produce sustained oscillations.
