Limnological survey of the warm monomictic lake Trichonis (central western Greece)

The physical and chemical status of Trichonis - the largest and deepest natural lake in Greece - is examined over two annual cycles (1985-86 and 1988-89). A correlation between lake nutrient patterns and phytoplankton biomass is attempted. Limnological features are compared with data from other warm and temperate lakes. With regard to its thermal regime, Trichonis is classified as a warm monomictic lake. The lake's stratification pattern and annual heat budget resemble those of other temperate lakes. Trichonis is a carbonate type, low conductivity lake ('cIass II, low salinity' warm lake). Nitrogen and phosphorus concentrations were rather low. The inorganic nitrogen content fluctuated widely over the two annual cycles examined. On the contrary, phosphorus concentrations showed no significant changes. The limiting factor during 1985-86 was P, while N was limiting during stratification in 1988-89. A weak correlation was found between the plankton community features (species abundance, biomass, chlorophyll-a) and light penetration. At present the eutrophication process from oligotrophy towards mesotrophy has not been essentially accelerated.