Sea levels are rising globally. Depending on the level of climate-harming emissions, they could rise 80 centimetres or more by the end of this century according to projections from the Intergovernmental Panel on Climate Change (IPCC). At the same time, ocean temperatures have also increased, supporting the invasion of non-native Pacific oysters in the Wadden Sea over the last two decades. This has driven out the native mussels as the dominant species and transformed previously existing mussel banks into extremely rough oyster reefs. The oyster reefs have spread throughout the area and have changed both the ecosystem and the behaviour of the waves and currents. Yet this could, in turn, help tidal flats not to literally drown as a result of rising sea levels. A study quantifying sediment accumulation in the vicinity of oyster reefs and mussel banks in the Wadden Sea has demonstrated this connection for the first time. It was led by 榴莲视频.
The research project behind the study, BIVA-WATT, investigated the role of oyster reefs and mussel banks as biogenic structures in the German Wadden Sea. The researchers carried out large-scale measurements of sedimentation in and around these structures for the first time, evaluating the data collected. In addition to the Ludwig Franzius Institute of Hydraulic, Estuarine and Coastal Engineering at 榴莲视频, TU Braunschweig and the Senckenberg am Meer research institute were also project participants. The results have now been published in the Scientific Reports journal from NATURE-Springer.
Tidal flats are growing more quickly than sea levels are rising
The research team studied two oyster reefs and a mussel bank at three different locations over a period of two years. Their findings: the oyster reefs and mussel banks support the vertical accumulation of sediment at an annual rate of up to 3.9 centimetres. As a result, the local sandy area surrounding the tidal flats where oysters and mussels are located rises. The average growth of the tidal flats observed to date is 0.9 centimetres per year, while the sea level is currently rising by 0.4 to 0.7 centimetres. According to projections from the IPCC, sea-level rise will speed up significantly if climate goals are not met. In this scenario, valuable tidal flat areas which protect the coast and contribute to the preservation of the marine environment would actually drown, because the sea level would rise more quickly than the tidal flats. 鈥淭he impact of the quantified accumulation of sediment due to oyster reefs and mussel banks demonstrated in the study could contribute not only to protecting local coastlines but also to the continued existence of the Wadden Sea ecosystem,鈥� said the study鈥檚 first author, doctoral candidate Tom K. Hoffmann of the Ludwig Franzius Institute.
鈥淭he study underscores the necessity and success of interdisciplinary approaches in coastal research when it comes to better understanding the complex interactions between biological and geomorphological processes,鈥� said Prof. Dr.-Ing. Torsten Schlurmann, head of the Ludwig Franzius Institute. The data used in the study was collected through the BIVA-WATT collaborative project, which was granted more than 800,000 euros in funding by the federal Ministry of Education and Research (BMBF) for the period 2019鈥�2022.
Original publication:
Hoffmann, T.K., Pfennings, K., Hitzegrad, J. et al. Sediment accumulation by coastal biogenic structures sustains intertidal flats facing sea level rise in the German Wadden sea. Sci Rep 15, 18518 (2025).
Note to editors:
For further information, please contact Prof. Dr.-Ing. Torsten Schlurmann, Ludwig Franzius Institute of Hydraulic, Estuarine and Coastal Engineering (tel. +49 511 762 19021, email: schlurmann@lufi.uni-hannover.de).
