Validating chlorophyll-a concentrations in the Lagos Lagoon using remote sensing extraction and laboratory fluorometric methods

Remote sensing data is a viable alternative for mapping pigment concentrations in water body, and consequently, the trophic. Chlorophyll-a (Chl-a) is present in all phytoplankton species. This study therefore uses laboratory fluorometric and remote sensing extraction methods for assessing chlorophyll-a concentration in the Lagos Lagoon. The fluorometer was calibrated with a commercially available chlorophyll-a standard before used in the laboratory to estimates chlorophyll-a concentration. Landsat 7 (ETM+) and Landsat 8 (OLI) were acquired for the remote sensing method. The Landsat data were first geometrically rectified. Then brightness values were converted to reflectance through the radiometric correction process. For the regression models, logarithmically transformed chlorophyll-a was used as the dependent variable. Single bands, band ratios and logarithmically transformed band ratios were the independent variables. R2 values were computed and evaluated. • Chlorophyll-a contributes to productive water bodies; • laboratory fluorometric and remote sensing extraction methods; • Landsat data acquired for the remote sensing method.