Stable oxygen isotopes as recorders of salinity and river discharge in the German Bight,North Sea

A high-resolution sediment core (sedimentation rate ~2 mm/year) from the German Bight was analysed for its foraminiferal stable oxygen isotope (¹⁸O) composition. These data were correlated with instrumental summer sea-surface temperature and salinity data from the nearby island of Helgoland, reaching back 100 years. Comparing the isotope data with the instrumental records reveals a distinct ¹⁸O–salinity relationship (¹⁸O=0.34×S–9.36; r=0.86) for the German Bight, where salinity is mainly driven by freshwater input from the Elbe River. Thus, these findings provide the possibility for future regional paleosalinity and paleodischarge reconstructions for times far beyond the instrumental timescale.