| Zusammenfassung: | Lake Pamvotis is a shallow urban Mediterranean lake located in northwestern Greece (region of Epirus). During the last three decades, the trophic status of the lake has changed as a result of anthropogenic activity and especially domestic sewage discharge, resulting in severe deterioration. During the 1980s, the lake has been stocked with several native fish species and some exotic herbivorous species (e.g., Ctenopharygodon idella), which resulted in a great decline of submersed vegetation. Ten years ago, a diversion of the sewage effluent was established to reduce external nutrient loads and improve water quality. Nowadays, the aquatic vegetation is mainly located at the northern littoral zone of the lake, and estimated to cover only about 5-10% of the total water surface of the lake. The main purpose of this study was to evaluate the aquatic macrophytic vegetation of lake Pamvotis and to investigate the spatial distribution of water quality among the remaining aquatic vegetation groups. Five major groups and six subgroups of aquatic vegetation were derived from a TWINSPAN classification. Water quality parameters (nitrate, nitrite, ammonium, DIN, SRP-soluble reactive phosphorus, carbonate, bicarbonate, chlorophyll-a), were determined while pH, conductivity, surface DO and Secchi depth were measured monthly in situ during the vegetated periods of 2004 and 2005. One-way ANOVA and CCA ordination revealed significant differences and relationships regarding the environmental variables among the distinguished vegetation groups. The results showed that SRP, pH, transparency, ratio transparency to water depth and total inorganic carbon, were significantly different among these vegetations suggesting the existence of different macrophytes-based mechanisms affecting main parameters of water chemistry. The potential role of floating-leaved vegetation in lake restoration is discussed.
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