SPATIAL AND TEMPORAL VARIATION OF CHLOROPHYLL 'a' ALONG THE DANUBE RIVER

The spatial and temporal variation affects the processes and patterns of the environment, particularly in structured systems such as river networks. Chlorophyll is bound within the living cells of algae and other phytoplankton found in surface water. The aim of the study was to describe the seasonal and spatial distribution of surface chlorophyll a (Chl a) in relation to some environmental variability factors, based on data collected in 2012 from 16 sampling sections along the Danube river. The concentration of Chl a was measured from the surface layer using a spectrometric method and the values ranged from 2.3 mu g/l in November to 68 mu g/l in July. Chl a showed temporal variability related to the anthropogenic pressures and meteorological conditions. After significant lower concentrations in late spring and early summer, Chl a exhibited its strongest maximum in summer: July and August. The high concentration of ail a indicated high productivity, also noted in numerical abundance and biomass of phytoplankton. The understanding of CM a, phytoplankton population and its distribution enables researches to draw conclusions about a water body health, composition and ecological status.