anthropogenic disturbances in regulated lakes Elisabetta Garofalo*; Paola Annoni**, Reiner Bruggmann*** 8th Partial Order Workshop on Hasse Diagram, Partial Order and Applications Varsavia, 22-24 Ottobre 2008 * CESI RICERCA ** UNIVERSITÀ STATALE DI MILANO *** LEIBNIZ-INSTITUTE FOR FRESHWATER ECOLOGY AND INLAND FISHERIES The use of phytoplankton as a quality indicator has been adopted by the European Water Frame Directive issued in 2000 (WFD 2000/60CE), which has widen the connotation of biological survey by shifting the attention from an anthropocentric view of natural systems towards a more ‘eco-centric’ view. This new perspective implies that biocenosis must be kept at a high ecological level notwithstanding their direct exploitation. However at the moment the WFD implementation is still at an early stage and many are the issues opened by the directive. The latest European call on the Environment (Assessing the ecological status of water bodies) testifies the need of a concrete contribution to the definition of classification methods recommended by WFD, with particular focus on lakes, transitional and coastal waters. Within this framework, the paper offers an insight into phytoplankton communities living in hydrologically regulated lakes. Data come from an extensive survey carried out during 2004 in nine Italian reservoirs which are exploited at different levels for power production. Phytoplankton communities are investigated at the order level. Authors followed a multi-dimensional approach with the goal of identifying the level of sensitivity of algae communities to anthropogenic disturbances which describe artificial hydrological regulation and water quality. Results highlight two groups of algae orders: one consisting of algae with their own regulation mechanisms, which are in conflict with the mechanism of reservoir regulation. The other consisting of algae which adapted to anthropogenic disturbances in some way and can then be considered robust to exploitation. This approach, if applied and further confirmed in similar water bodies, may be used for optimizing the experimental effort providing methods for ecological classification which are cost-effective, as explicitly recommended in the 2008 European call on Environment. KEYWORDS: phytoplankton, artificial lakes, partial order, Hasse diagram, sensitivity analysis averaged ranks, similarity analysis