Seasonality of phytoplankton as an indicator of trophic status of the large perialpine ‘Lago di Garda’

The seasonality of phytoplankton and its vertical distribution in Lake Garda, Italy, was studied on the basis of monthly sampling during 1994. Chlorophyll a concentration, phytoplankton biovolumes and species composition are used for the trophic characterization of the lake, supplemented by water chemistry data (nutrients and total phosphorus) and Secchi depth. Horizontal differences in trophic status are investigated by comparing data from three sampling stations, whereas the long term changes in trophic status are based on a comparison of the recent findings with earlier studies of the phytoplankton.