Detecting cyanobacterial blooms in large North European lakes using the Maximum Chlorophyll Index

The Maximum Chlorophyll Index (MCI), developed for the MERIS sensor processing scheme, is used to investigate the seasonaldynamics, spatial distribution, and coverage of cyanobacterial blooms over Lake Peipsi (Estonia/Russia) and Lake Võrtsjärv(Estonia). In these optically complex waters, the amounts of suspended matter and dissolved organic matter vary greatly andindependently of the phytoplankton biomass. We demonstrate that MCI is a useful, new tool for detecting and estimating cyanobacterialbiomass (R2 = 0.73), phytoplankton biomass (R2 = 0.70) and chlorophyll a concentration (R2 = 0.64). The MCI-derivedresults are consistent with known patterns of phytoplankton dynamics in these lakes, whose optical properties are in the same range as in many coastalregions of the Baltic Sea.