Phytoplankton-based shallow lake types in the Carpathian basin: steps towards a bottom-up typology

As lake biota are basically determined by hydromorphological characteristics of the lake basin, establishment of a lake typology is the first step in lake quality assessment and management. Based on descriptor variables (size, depth, lake bed material, water-regime and macrophyte coverage), 16 hydromorphological lake-types were established for the Pannonian Ecoregion. Our analyses revealed that descriptor variables have considerable effect both on biomass and composition of phytoplankton. As the phytoplankton biomass of several lake-types can be merged, a simplified typology can be proposed. Since the phytoplankton composition of various lake-types differed significantly in terms of diversity and relative abundance of functional groups, well delineated composition-based types cannot be established for Pannonian lakes. Although the Pannonian Ecoregion is the westernmost part of the Eurasian steppe zone, the proposed typology of the studied area can be extended to lakes of the greater Pannonian region.