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Gribat kauko patiesi skaistu ? lūk !
Successful lake management requires a close cooperation between science and decision makers. In this paper we propose a novel approach to setting targets for the ecological status of lakes of Central Europe. As a first step, we developed a conceptual model for “good” ecological status of lakes and dose - response relationships between eutrophication pressure (expressed as total phosphorus and chlorophyll-concentrations) and biological communities (taxonomic composition of phytoplankton and macrophytes, colonization depth and abundance of macrophytes). Next, we established “good” status boundaries based on non-linear responses of biological communities to eutrophication pressure, e.g., shift in phytoplankton composition to light competitors (Cyanobacteria), decrease of macrophyte abundance and colonisation depth. Shallow lakes alternative stable state theory (Scheffer, 1998) was elaborated, defining a range of chlorophyll-a values were shift from vegetation dominated community with clear water to a phytoplankton dominated community with clear water occurs, marking a “good” - “moderate” status boundary or shallow lakes of Central Europe. In conclusion, our work resulted in chlorophyll-a ecological status boundaries which were recently formulated in the EC decision (EC, 2009) and, for the lakes, would form a base for the objective setting for the River Basin Management Plans in Europe. |