Development of tools for ecological quality assessment in polish marine areas according to the Water Framework Directive. Part II — Chlorophyll-a

To implement the EU Water Framework Directive (WFD) it is necessary to establish tools enabling ecological status quantification on the basis of biological indicators, and to assess reference conditions and relevant environmental pressures for the construction of response curves. This study focuses on the Polish sector of the Baltic Sea. A number of statistically significant linear correlations, linking chlorophyll-a concentrations with pressure parameters, were found. Due to the lack of historical data, reference conditions and ecological class boundaries for chlorophyll-a assessment were determined using a simplified mathematical approach.