An evaluation of long-term physical and hydrochemical measurements at the Sylt Roads Marine Observatory (1973–2019), Wadden Sea, North Sea

A 46-year study at the Sylt Roads Marine Observatory in the Wadden Sea reveals significant long-term changes in sea surface temperature, salinity, and nutrient dynamics. Since continuous sampling began in 1984, sea surface temperatures have risen by +1.11°C, with the most pronounced increases observed during autumn months. Conversely, pH and salinity have decreased by 0.23 and 0.33 units, respectively. The study also documents periods of intense eutrophication (1973–1998) followed by de-eutrophication since 1999, with notable shifts in nutrient limitation for phytoplankton—from silicate limitation before 1998 to soluble reactive phosphorus (SRP) limitation afterward. Despite significant changes in nutrient concentrations, chlorophyll a levels showed no substantial seasonal differences between the two eutrophication periods, suggesting complex interactions driving phytoplankton dynamics. The research is based on twice-weekly measurements of physical and hydrochemical parameters, with data available via PANGAEA.

Rick, J. J., Scharfe, M., Romanova, T., van Beusekom, J. E. E., Asmus, R., Asmus, H., Mielck, F., Kamp, A., Sieger, R., & Wiltshire, K. H. (2023). An evaluation of long-term physical and hydrochemical measurements at the Sylt Roads Marine Observatory (1973–2019), Wadden Sea, North Sea. Earth System Science Data, 15(3), 1037–1057. https://doi.org/10.5194/essd-15-1037-2023