| Phytoplanktons are producers in aquatic ecosystem and are sources of energy to higher levels (consumers) of food chains and food webs. A simple mathematical model is described in the present paper called nutrient – phytoplankton model. This model tries to understand the dynamics of nutrient driven phytoplankton growth. In the literature surveyed so far, a large number of complicated simulation studies are reported. It is found in actual (realistic) field studies that the growth of the Phytoplanktons is strongly controlled by the nutrients rather than by consumer of higher trophic level (e.g. population densities). The present model is based on the assumption that the growth is accelerated when nutrients exceed a certain level (ecologically saying, that is, oligotrophic water resource turn into eutrophic one). This threshold effect should be generic to simulation models. |