Gridded abundance map of the invasive Polychaete Marenzelleria in the Baltic Sea

Gridded abundance map of Polychaete worm Marenzelleria. This animated gridded abundance map shows how the species invaded the Baltic Sea from Danish waters in the 1990s and became abundant throughout the whole region. This animation shows that probably multiple invasions occurred at the same time. The species is part of the Descriptor 2, Non Indigenous Species of the MSFD and is being monitored under HELCOM. The product was developed with DIVA (Data-Interpolating Variational Analysis) and shows the log-transformed abundance. Data was provided by Sweden (SMH - Swedish Agency for Marine and Water Management; Swedish Meteorological and Hydrological Institute (SMHI); (2015): SHARK - Marine soft bottom macrozoobenthos monitoring in Sweden since 1971)), Finland (SYKE) and Denmark (Aarhus University - Josefson, A.; Rytter, D.; Department of Bioscience - AU, Denmark; (2015): Danish benthic marine monitoring data from ODAM).