In- Situ Optical measurements of sediment type and phytobenthos of tidal flats: A basis for imaging remote sensing spectroscopy

For an accurate interpretation of air- and spaceborne imagery of the Wadden Sea, reliablein-situ optical data of the wide range of dominant surface types is required. The motivation for undertaking the present research was to create a statistically robust library of reflectance spectra of the most important surface types present in terms of areal cover. From this library of sprectra it was possible to create a procedure which enables a distinction to be made between different surface sediment types, the dominant phytobenthic species present on the tidal flats and to estimate the biomass of the microphytobenthos present based on the optical spectral signatures. Reflectance was measured in the optical window at 250 different sites in the German Wadden Sea. In parallel, pigment concentration of the microphytobenthos, grainsize and water content were also measured. The sites investigated covered the complete range of sediment types, which included different densities of the microphytobenthos and different species of the dominant macrophytes.