Bacteria of marine sediments play an important role in carbon and nutrient cycles. Due to their disposal of various genetic information and their competence for gen transfer bacteria have the capability to adapt to changes in their environment very fast. Thus investigating the bacterial community allows following changes, as result of anthropogenic origin in many cases, very early. Waterways form important networks in transport systems but due to tidal pumping effects sediment accumulates in coastal rivers intercepting them. Dumping this sediment into the sea is a common procedure to prevent its accumulation. The impact of these potentially polluted sediments on bacterial communities of unpolluted environments is barely investigated. In this study the dumping site Tonne E3 in the German Bight (North Sea, Germany) was examined. From 2005 to 2007 4.2 Mio m³ of excavated material from the Hamburg port area have been dumped into the North Sea. Further activities followed in the last years. In August 2009 sediment samples were taken at Tonne E3 to analyze the bacterial community via automated ribosomal intergenic spacer analysis (ARISA).The dumping area and a reference region were investigated. ARISA focuses on the length polymorphism of a highly conserved region in the bacterial genome providing a highly resoluted community pattern. The results revealed three community structures. One pattern occurred in the samples of the reference region and two others in the samples of the dumping site which differed to the community pattern of the reference. The different patterns in the samples suggest an impact of other variables such as the composition of the sediment. For a detailed insight into the community structure the patterns were further analyzed via distance matrices. Correlations with additional parameters, e.g. heavy metal contamination or CHN values were analyzed by gradient analyses to show relations with variables explaining the different patterns.