Phytoplankton Based Assessment of the Ecological Status and Ecological Potential of Lake Types in Bulgaria

ABSTRACT

Research has been carried out of the main characteristics of phytoplankton communities in order to assess the ecological status and ecological potential of the types of lakes in Bulgaria, according to the requirements of WFD 2000/60/EC. Eighty lakes/reservoirs have been researched on the territory of the Republic of Bulgaria. The assessment was made on the basis of four main metrics (phytoplankton biovolume; Algae Groups Index; transparency, chlorophyll a) and three additional metrics (% Cyanobacteria; intensity of algal “bloom” and presence of toxic species). More than half of the researched lakes in Bulgaria are in compliance with the WFD requirements for good ecological state (high and good ecological status, maximum and good potential). A classification system for assessment of ecological status or potential has been developed using above-mentioned phytoplankton metrics. The existing 17 types of lake in Bulgaria are classified in two main groups: oligotrophic lake types and mesotrophic lake types.

Keywords:

• Bulgaria
• ecological status
• ecological potential
• lake
• phytoplankton
• Water Framework Directive