DEVELOPMENT OF CLASSIFICATION SYSTEM AND BIOLOGICAL REFERENCE CONDITIONS FOR BULGARIAN RIVERS AND LAKES ACCORDING TO THE WATER FRAMEWORK DIRECTIVE

The study focused on sampling procedures and analysis of biological and physico-chemical quality elements (according to the EU Water Framework Directive (WFD)) and aimed at defining reference conditions and sites, maximum ecological potential, specific physico-chemical and hydromorphological conditions for assessed surface water types of rivers and lakes categories. Biological quality elements (BQE) and their metrics were selected in compliance with WFD requirements and its additional guidelines. All five compulsory BQEs were surveyed (phytoplankton, macrophyte flora, phytobenthos, macrozoobenthos, fish fauna) towards establishing rivers and lakes ecological status and potential. Current research indicates a certain necessity for integration of all assessments and analysis of ecological status/ potential and their direct link to the measurement and monitoring programmes in Bulgaria.