Phytoplankton in the ecological status assessment of European lakes – advantages and constraints

Although the phytoplankton indices describing the response of phytoplankton to the eutrophication have been developed and used for many years in the routine lake monitoring programme in some countries, the implementation of the Water Framework Directive (WFD) [EC, 2000] stimulated the development and improvement of quite a number of the current WFD-compliant phytoplankton-based methods. This paper is a review of the current phytoplankton-based methods for assessing the ecological status of European lakes. The particular attention was paid to the ways of solving problems arising from the need to reflect the complex and dynamic plankton algal communities on a numerical scale in order to gain reliable information about the state of the ecosystem.