Assimilation and turnover time of phosphorus by size fractions of microplankton in lakes of different types

Abstract

In a direction from oligotrophic lakes to more productive ones concentration of biologically available phosphorus (BAP) increased from 1 up to 35 μg/L, turnover time of BAP — from 19 up to 1300 min. Relative participation of phytoplankton and bacterioplankton fractions of microplankton in phosphorus assimilation depend on productivity of lakes. In oligotrophic lakes the phosphorus assimilation by bacteria reached 80–90% of total assimilation. As the trophic status of lakes increased the participation of bacteria in phosphorus assimilation decreased to 10–20%, accordingly assimilation activity of phytoplankton increased. It testifies to domination of phosphorus flow through microbial organisms (0.23–1.5 μm) in oligotrophic lakes.