History and Success of an Invasion into the Baltic Sea: The Polychaete Marenzelleria cf. Viridis, Development and Strategies

Abstract

In the mid 1980s, a new polychaete appeared in coastal waters of the Baltic Sea and rapidly became an important faunistic element. The identification of this spionid as Marenzelleria cf. viridis indicated North America as the most likely area of origin. The history of invasion into the Baltic Sea is outlined. Sound taxonomic experience and competence was and is necessary to elucidate the background when dealing with bioinvasions. A review of taxonomic problems of the genus Marenzelleria is given. Based on long time series we could draw a picture on the species strategy in stressed habitats. Three coastal areas were selected to demonstrate the role of environmental factors facilitating Marenzelleria invasion in the Baltic Sea in the last decade. This review deals with the expansion and niching of an allochthonous species and its influence on the indigenous macrozoobenthos. Both the life history and physiology of Marenzelleria make it well adapted to life in brackish water conditions, occupying a niche in an environment with low species diversity.