The annual distribution of nutrients in a selected section of the river Axios exhibited different patterns of change. The prevelance of very high concentrations of phosphate phosphorus and their continuous fluctuations may indicate the anthropogenic effect on the distribution of this nutrient. The high levels of TIN and silicon may result from the maximal inflows reaching the river. Chlorophyll a concentrations displayed their minimum when nutrients were available. A total of 119 taxa were identified in the phytoplankton.