Distribution of Planktonic Primary Production in the Black Sea

Planktonic primary production data from the entire Black Sea are reviewed for the last two decades. Surface and vertical profile of data are spatially and seasonally compared for different significant areas (north-western shelf, western and southern coast, eastearn and western halistatic zones). High production rates, especially in the coastal waters of the NW and W Black Sea exhibit large inter- and intraseasonal variations. Such values clearly reflect meso- and eutrophic feature of these waters. There are major annual spring (diatoms) and autumn (coccolithophorids) blooms, followed in recent years by additional summer (dinoflagellates, coccolithophorids) blooms. The major primary producers are usually Skeletonema costatum, Chaetoceros curvisetus, Peridinium trochoideum, Exuviaella cordata and Prorocentrum micans. Factorial analyses reveal very high correlation coefficients between chlorophyll a concentration and salinity, primary production and salinity, and between chlorophyll a concentration and primary production. The annual cycle of plankton dynamics in the central Black Sea is being studied by means of an one-dimensional vertically resolved physical-biological upper ocean model, involving interactions between inorganic N (NO3, NH4), phytoplankton and herbivorous zooplankton, and detritus.