The seaweed dominated rocky intertidal flats of the island of Helgoland (North Sea) are characterized by geo-morphologically and ecologically small-scaled structures (<10m). Synoptic acquisition of biotope information of the whole area is only possible via airborne remote sensing. Four spatially highly resolved hyperspectral AISA Eagle images (~1 m ground resolution) have been recorded over the year 2008 in order to (1) investigate spatiotemporal changes of the intertidal/sublittoral fringe seaweed vegetation, and to (2) spectrally characterize mixed vs. uniform vegetation units. Geometric correction of AISA Eagle flight lines has been enhanced to sub-meter precision with help of an additional GPS basis station. Reflectance spectra of characteristic seaweed species and biotopes have been collected with a field spectrometer and selected small-scale areas have been mapped and geo-referenced in detail and transferred into a GIS to validate the airborne sensor data and to set up a spectral library. A main goal of the classification is the distinction of algal species based on their spectral reflectance. Our results from field spectroscopy of dominant brown algae indicate that differentiation between brown algal genera (Fucus, Sargassum, Laminaria) is possible. Endmember extraction and species classification were implemented by SMACC and Spectral Angle Mapper. The seasonal variations in the spatial extent of green algal dominated biotopes, of serrated wrack (Fucus serratus) populations and of the invasive Japanese wireweed Sargassum muticum will be demonstrated.The research was performed in the framework of two projects InnoHyp and CoastEye financed by the cities of Bremen and Bremerhaven.