The seafloor topography of the reference areas is mapped by ship based multi-beam echo sounder surveys; e.g. a Kongsberg EM710 system on the research ship FS Heincke. Subsequent analyses correct for ship movement and tidal effects to derive the bathymetry and acoustic properties of the sea floor at high accuracy. Acoustic properties as the backscatter intensity are further interpreted for classification of bed sediments and bottom relief by an angular range analysis. Small bed features and the sediment mobility are observed by 3D bed sonars mounted on autonomous sea floor observatories (landers). The high resolution MBES bathymetry complements earlier large scale data by the federal authorities (BSH).
Bed sediments and benthic species at the sea bed surface of the reference areas are sampled by grab samplers (Shipek, Van Veen), box corers, and multi-corer (MUC) equipment. A sedimentological description and granulometric analysis (laser diffraction) of the sediments is carried out, and sediment samples are stored for subsequent analyses. Habitat characteristics are specified and benthic fauna is characterized by taxonomy, number, biomass, and bioturbation potential. Analyses for organic pollutants are carried out by gas chromatography GC_MS_MS for target chlorinated hydrocarbons (CHCs) and polyaromatic hydrocarbons (PAHs). Dissolved concentrations of hydrophobic organic pollutants (PAH, PCBs, organochlorine pesticides) in the sediment porewater are measured.
Fishing pressure is an ecosystem indicator which can be expressed by the trawling intensity that is estimated from Vessel Monitoring by Satellite data (VMS)
All data is inter-compared to results from large scale interpolations of existent data bases and large scale model results. These comprise grain size data, total organic carbon, and the mud content of surface sediment grab samples. Exemplary current velocities and bed shear stresses were calculated by a numerical model. Sea water temperature are given based on BSH measurements and model runs.