Marine Habitat Mapping in Germany: Application, Progress and Challenges

The increasing demand by national legislation and European marine policy amplifies the need for high resolution and area-wide habitat maps of the seafloor. The basis for a consistent and objective delineation of habitats is a consistent derivation of sediment classes. For this reason, the German Federal Maritime and Hydrographic Agency (BSH) has published a guideline for high-resolution, hydroacoustic sediment mapping, with the advice of scientific experts. Large areas within the German exclusive economic zone, in particular in the special areas of conservation (SAC) have already been mapped in agreement with this guideline.We will introduce the mapping guideline and its sediment classification system, present the mapping progress and demonstrate the successful use of sediment maps for the creation of habitat maps. The approach by the BSH works very well for the large-scale mapping of the German North and Baltic Sea. However, more specific tasks like environmental investigations for approval procedures or scientific questions need adjustments to the mapping criteria. We will show this exemplary for hard substrate habitats. According to the guideline of the BSH (update is in progress), hard substrates presence is given as raster information with cell size of at least 100 x 100 m. For e.g. approval procedures, this raster information is not sufficient to map the protected natural habitat "reefs" in a large scale. Therefore, the German Federal Agency for Nature Conservation (BfN) has developed its own criteria where individual objects have to be detected. The object detection is still to be done manually which might be acceptable for small study sites, but not practicable for large-scale mapping. Consequently, current work is concerned with the automation of object detection to speed up the interpretation and make it objective / reproducible.