Lake Koronia, a wetland in gradual recovery process or a flash from the past?

Abstract

Lake Koronia, Greece, is a wetland of international and European importance (Ramsar and Natura 2000 site). The lake has deteriorated in terms of habitats, water quantity and quality since 1995, resulting in mass fish and bird deaths. We monitored abiotic and biotic (aquatic macrophytes) parameters between 2015 and 2021 to investigate recovery progress, following implementation efforts of a restoration plan. Abiotic conditions were recorded monthly/seasonally, while vegetation data were recorded in two periods (June 2017, 2020). After an initial considerable increase in water level, mean annual values fluctuated at around 70-71 m asl. Water transparency values were low while conductivity values were high. Three vegetation units were present: Lemnetea, Potamogetonetea and Phragmitetea, represented by few taxa. Helophytic taxa formed a narrow littoral reedbed (< 10 % of the lake area). Few rooted hydrophytes were present but limited to sparse patches (< 5 % of the total abundance). These results indicate that vegetation stabilization or even further expansion could be possible, given that hydrological and physicochemical conditions improve. The possible recovery of this fragile ecosystem depends on both the mitigation of anthropogenic pressures and favourable natural conditions. The continuation of restoration measures and monitoring efforts are considered necessary in this direction.