QUANTITATIVE RELATIONSHIPS BETWEEN PHYTOPLANKTON, BACTERIA AND PROTISTS IN AN AEGEAN SEMIENCLOSED EMBAYMENT (MALIAKOS GULF, GREECE)

The seasonal variations of temperature, dissolved organic carbon (DOC) , chlorophyll a (chl a), and bacterial and protistan abundance were in vestigated in an enclosed Eastern Mediterranean embayment over an 8 mo period. DOC levels in the gulf were high, likely due to allochthonous input through freshwater discharge. However, after the end of spring, when allochthonous input was minimal, bacterial abundance was linearl y related to chi a and DOG, suggesting that during this period the rem aining DOC pool (probably autochthonous DOG) was important. Bacterial abundance was significantly correlated with the biomass of the phytopl ankton at the end of spring and throughout summer. A correspondence of protistan abundance with bacteria, especially during the warm months, when the phytoplankton biomass was low, suggests that the microbial l oop is the dominant component of the food web structure during the oli gotrophic period of the year.