THE MODEL OF SEASONAL DYNAMIC OF PLANKTON COMMUNITY BIOMASS IN THE OCEAN

The mathematical model is proposed to study the seasonal fluctuation o f phyto- and zooplankton biomass in the ocean at different latitudes. It is assumed that relation between particular trophic levels are of ' 'predator - prey'' type. The analysis of the results shows that in tem perate and high latitudes biomass dynamic is characterized by clearly distinct pick in spring and early summer, moderate second pick and sta tionary state in winter when there is no predation. The fluctuations o f biomass are not very large in tropics, while closer to the equator t hey become more harmonical. The model under study can be considered as a part of the model of global nitrogen anti phosphorus cycles in the ocean. The changes of phyto- and zooplankton biomass as well as in N a nd P concentration are presented as three-dimensional pictures, The mo del shows that the decrease in total N and P results in the generation of 2, 3 and 4-years cycles in temperate and high latitudes.