Relating chlorophyll from cyanobacteria-dominated inland waters to a MERIS bloom index

The cyanobacteria index (Cl) has been applied to Medium Resolution Imaging Spectrometer (MERIS) imagery to characterize cyanobacterial biomass in diverse regions. While a consistent qualitative estimate of cyanobacterial biomass is useful, establishing universal relationships to chlorophyll a (chl) concentration, the dominant photosynthetic pigment in phytoplankton, would quantify blooms for regional comparisons. Relationships between chl concentrations were determined from water reflectance measurements and chl concentration from water samples taken from cyanobacterial blooms in eutrophic lakes in Florida, where chl ranged from 16 to 115 mu g L-1. When the chl relationship was applied to simultaneous satellite and field data, the chl concentration determined from satellite Cl showed negligible bias and root mean square error of 27%. The generic Cl-based chl algorithm presented here seems suitable for consistent quantification of chl concentration within cyanobacterial blooms.