X-ray fotos of 10 sediment cores from the Baltic Sea

Various types of trace fossils have been studied on radiographs of sediment cores from the Western Baltic since the early nineteen sixties. lnvestigations on the endo- und epifauna including their habitats and population densities carried out independently by biologists helped to identify the processes of their formation and classify the structures. Biogenic traces are ubiquitous in both sandy and muddy sediments of the Great Belt, where the bottom waters are weil oxygenated through inflows from the North Sea (through Kattegat-Skagerrak). Almost all types of bioturbation structures encountered in the Kiel Bay are also observed in a variety of shapes and forms, and can be considered as representative for the Western Baltic area. Polychaetes, bivalves and echinoderms were recorded at the sediment surface of the cores, and also in living positions in the sediment. The different types of burrows having distint outlines ('trace fossis'), and those having indistinct outlines ('biodeformational strctures'), and their varying abundance encountered in the area have been linked, wherever possible, to the sediment type, and to the macro-benthos.