Introduction
Globally, marine restoration has become an increasingly important measure to regenerate ecosystems, protect biodiversity, and support ocean sustainability. In Denmark, marine nature restoration is still a relatively new field, and significant experience and knowledge have been built up over the past 15–20 years, through the implementation of various research and citizen-based projects in Danish waters. These initiatives have primarily concentrated on establishing boulder reefs and eelgrass meadows, while the restoration of shellfish beds was only initiated in recent years.
In 2022, the Center for Marine Restoration (CMR) was founded. CMR is a Danish national centre that spans four institutions: Technical University of Denmark, University of Southern Denmark, Aarhus University, and The Limfjord Council (a local organisation of municipalities around the Limfjorden). The purpose of CMR is to ensure that marine nature restoration in Denmark is carried out on a knowledge-based foundation by collecting, mapping, and analysing existing and new knowledge, and by providing this expertise to local, municipal, and national stakeholders to support the successful implementation of different types of marine restoration projects.
Results
Along the shallow Danish coastlines, the current shellfish beds are dominated by blue mussel beds (Mytilus edulis), whereas horse mussels (Modiolus modiolus) and European flat oysters (Ostrea edulis) occur only sporadically, if at all. This presentation focuses on the restoration of blue mussel beds, outlining their historical national distribution and reviewing the key ecosystem functions they support. This is followed by an update on recent trends in international and national mussel populations, demonstrating that the natural formation of stable mussel beds is under pressure and needs active restoration in Denmark. Finally, the common CMR guidelines for restoring blue mussel beds will be introduced, together with updates on experiences from restoration efforts in Danish waters.
Acknowledgment
The Center for Marine Restoration is funded by the Velux Foundation and the Danish Ministry of Environment and Gender Equality.