The present PhD-thesis contributes to assess the ecological consequences of the invasion of Marenzelleria spp. in the Baltic Sea. The spionid polychaetes of the genus Marenzelleria spp., consisting of the sibling species M. neglecta, M. viridis, and M. arctia have been found in the Baltic Sea since the 1980s. Because of difficulties in species identification, little is known about their species dependent sediment reworking and solute transport pattern as well as their effects on the biogeochemistry of bioturbated sediments. These potential differences were examined in laboratory experiments.<eng>
