Measurements of inorganic nutrients, phytoplankton cell densities and
benthos biomass were carried out at different stations off Constanta,
on the Romanian shelf and in the Danube River by the Romanian Institut
e of Marine Research between 1959 and 1992. Measurements in the Sulina
branch of the Danube reveal that there was a five- and two-fold incre
ase, respectively, of the total inorganic nitrogen and phosphate loads
of the Danube River, whereas the riverine input of silicate decreased
to about one-third. In addition, industrial waste waters contribute t
o this input-especially phosphate, Distinct increases of phytoplankton
cell densities, as well as the frequency of algal blooms, were report
ed. There was a more than double decrease of benthic biomass in the Ro
manian shelf area due to suboxia in the bottom water after the sedimen
tation of algal blooms.