Summary
5 field studies, each of 15 days long, with experimental enclosures (fertilized and not fertilized) and daily measurements of physico-chemical and microbial parameters (nitrogen forms, bacteria, phyto- and zooplancton), allowed us to specify the nitrogen compounds transformation and the part of microorganisms in water column.
Nitrogen dynamics and microbial activities of the water column are studied using size fractionation of plancton.