Efficiency of Transfer of Essential Substances from Phytoplankton to Planktonic Crustaceans in Mesotrophic Lake Obsterno (Belarus)

The efficiency of transfer of essential substances (carbon, phosphorus, nitrogen, and fatty acids (FAs), including polyunsaturated fatty acids (PUFAs)) from phytoplankton to zooplankton in three habitats (pelagic zone and vegetated and unvegetated littoral areas) in mesotrophic Lake Obsterno (Belarus) has been assessed. The efficiency of transfer of substances was calculated as the ratio of their secondary production to primary production per water volume unit and biomass unit. The efficiency per water volume unit can characterize the efficiency of transferring substances in a lake, while the efficiency per biomass unit indicates the ability of zooplankton to accumulate essential substances consumed with the food resources in biomass, i.e. it characterizes the quality of zooplankton as a resource for higher trophic levels. The efficiency of PUFA transfer was lower than the carbon transfer efficiency. On the contrary, the accumulation of nutrients, especially phosphorus, was more effective when compared with the carbon accumulation rate. This indicates that zooplankton serve as a sink for nutrients which are transferred up the trophic webs. The plankton communities in the pelagic zone of mesotrophic lake were found to be more effective in transferring the substances from the primary producers to the consumers than the littoral communities were.