SPATIAL AND TEMPORAL VARIATIONS OF COLOURED DISSOLVED ORGANIC MATTER IN THE SHALLOW EUTROPHIC LAGOON

In this study spatial and temporal distribution of coloured dissolved organic matter (CDOM) was studied in the shallow eutrophic Curonian Lagoon in spring and summer from 2005 to 2011. CDOM is one of the main components that contributes to water colour and have different origins: terrestrial and autochthonous. Due to ongoing eutrophication increased CDOM concentration can affect primary production and ecosystem structure by reducing the amount and quality of photosynthetically active radiation to phytoplankton and macrovegetation. MERIS/Envisat (satellite of European Space Agency) were used and CDOM was derived after application of Boreal Processor. Two-band semi-empirical algorithm that uses the reflectance peak in the red and near-infrared (NIR) spectral regions was applied in order to get chlorophyll a (chl a). We obtained that 1) there was high seasonal pattern in CDOM concentration, its higher values appeared in spring as an outcome of high river loads after ice melting and rain; 2) during summer CDOM concentration differed spatially: higher CDOM values occurred close to the mouths of Rivers and in the southwestern part of the lagoon, which is often affected by intensive primary producers bloom, and possibly high phytoplankton degradation could increase CDOM concentration there. Environmental conditions (wind speed and direction, river discharge, temperature, precipitation and chl a) were important for the explanation of spatial and temporal distribution patterns. Financial support provided by European Social Fund Agency project "Development of Technological and Environmental Researches in Lithuanian Marine Sector", Nr. VP1-3.1-?MM-08-K-01-019.