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ALGAL BLOOMS AND DEVELOPMENT OF THE MAIN 
PHYTOPLANKTONIC SPECIES AT THE ROMANIAN BLACK SEA 
LITTORAL UNDER EUTROPHICATION CONDITIONS



N. Bodeanu

Romanian Marine Research Institute Constanta

Abstract
The growth of the mineral salts and organic matter stocks in the
western Black Sea, induced by the intensification in the 8th and 9th
decades of the antrophic activity in the pontic basin, in Danube and
other tributary rivers, determined the increase of the frequency and
magnitude of the algal blooms with their negative consequence for 
ecosystems. More than 20 monospecific algal blooms have occured in 
the Romanian coastal waters between 1983 and 1988. Out of the eight
species responsible of the phenomenon, five species achieved the
greatest blooms ever known until now at the Romanian littoral. Except
the algae which produce monospecific blooms, some other numerous
species recorded remarkable developments. The number of species with
high numerical densities (over 100,000 cells l-1) increasing from a
period to another, reached 72 in 1983-1988, if compared with 61 in
1971-1982 and only 38 in 1960-1970. Out of the total mass species
which developed between 1960-1988, over than 50% reached the 
greatest developments in 1983-1988. The great intensity of the
blooming phenomena, the growth of the mass species number and the
increase of their density induced high levels of the global
phytoplankton quantities. Ever rising from period to period, medium
biomass for the Romanian Black Sea area was ten times greater in 
1983-1988 than 1959-1963.