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The Eastern Mediterranean is one of the world's most oligotrophic seas characterized as a "marine desert" because of the impoverished phytoplankton biomass and productivity levels mainly due to phosphorus deficiency. The Aegean Sea is classified among the most oligotrophic areas of the Eastern Mediterranean Sea, but despite its oligotrophic nature, relatively eutrophic waters do exist mainly in the north and northwest part of the area.

In the present paper, the spatial and temporal variation of the phytoplanktonic primary production rate of the Aegean Sea is examined. The study is based on a five-year dataset of Coastal Zone Color Scanner (NIMBUS 7 - CZCS) satellite sensor images, with a spatial resolution of one square kilometre and a temporal resolution of one image per month approximately. The satellite images were processed to apply sensor calibration, to correct for atmospheric contamination and to estimate chlorophyll like pigment concentrations. Pigment concentrations along with a set of climatological data (Photosynthetically Available Radiation (PAR), Cloud Index, etc) were used as input parameters in a semi analytical marine primary productivity estimation model, in order to develop a series of phytoplanktonic productivity distribution maps of the study area.

The results showed a presence of enhanced algal biomass in the northern part of the Aegean Sea and reduced phytoplanktonic primary production rate in the southern part of the area. Generally, the Aegean Sea is characterized by an almost permanent, throughout the year, gradient of decreasing primary production rate towards the North to South direction. This can be attributed to the significantly different hydrographic characteristics between the North and South Aegean subbasins that are separated by the Cyclades plateau and are influenced by the Black Sea waters and Levantine Sea waters, respectively. Finally, high phytoplanktonic primary production rates are also observed in semi enclosed gulfs and coasts and especially in areas that urban and / or industrial waste deposition takes place.