Microphytobenthos biomass and production monitoring on intertidal mudflats using remote sensing

Coastal areas and estuaries are ecosystems with a high economical and ecological value. Sediment-inhabiting microalgae (microphytobenthos) form thin biofilms on intertidal mudflats and are important for stabilizing the sediment and transferring inorganic nutrients to the estuarine foodweb. Knowledge about the microphytobenthos distribution and production is therefore essential for the management of these areas. As intertidal mudflats are not easily accessible for routine sampling and show high spatial and temporal variability, remote sensing techniques are increasingly used for monitoring these areas. The potential of remote sensing techniques however is still not fully explored. Using a large dataset of field spectra, Chl a and environmental data from different projects and field campaigns in Northwestern Europe, we explored the performance of a wide range of measures. These measures were both obtained from literature and from testing high scoring wavelength combinations of the type ration (i/j) and vegetation index (i-j)/(i+j). A number of the tested measures performed well, compared to the NDVI as a baseline index, and could be successfully applied using simulated multi- and hyperspectral sensors bands. Based on our data we also formulated recommendations for obtaining more reliable ground-truth data by restricting sampling to a specific time frame around low tide.