Reintroduction of the European Oyster in the German North Sea: Establishing sustainable seed oyster production for a long-term reintroduction programme
The European oyster Ostrea edulis, once a widespread species in the North Sea, is considered functionally extinct in some regions due to intensive fishing. As an ecological key species, it had many positive effects on other plant and animal species and provided important ecosystem services for the surrounding ecosystem. Due to its preference for settling on the shells of conspecifics, it over generations gradually forms a biogenic reef. These reefs provide food, shelter and habitat for a variety of other species. An intact oyster reef thus directly increases the biodiversity of the ecosystem.
Within the ongoing project RESTORE, a pilot reef of the European oyster is currently planned and established as a nature conservation measure. In 2020, it will be built up in the Borkum Reef Ground SAC and biologically and ecologically monitored over the next years.
The PROCEED project builds on important interim results of RESTORE with respect to the reintroduction of the European Oyster Ostrea edulis in the German North Sea. It is funded by the German Federal Agency for Nature Conservation, BfN, with funds from the German Federal Ministry for the Environment, BMU, as part of the Federal Biodiversity Programme.
Project term 2018-2024
A stable seed oyster production is an obligatory basis for the successful reintroduction of the European oyster. In identifying donor populations and sources of seed oysters for reintroduction, it became clear that only a few hatcheries within Europe still produce suitable seed oysters of this species. In order to ensure a long-term availability of young oysters, PROCEED is building and operating a technologically innovative hatchery at the AWI site Helgoland to establish a healthy parent broodstock and the production of suitable seed oysters. Accordingly, biological and technological research questions in this field will be identified and findings will be directly implemented. The aim is to support a long-term restoration programme by providing a sufficient supply of seed oysters, thus ensuring the preservation and enhancement of biological diversity through the oyster reef habitat.
Knowledge transfer to society
The European network NORA (Native Oyster Restoration Alliance) was founded in 2017 on the initiative of AWI and BfN. As an international platform, NORA will facilitate strategy development in the areas of monitoring, biosecurity, production and technology transfer between current and future restoration projects. This cooperation is intended to support the strengthening of the native species population in its entire European distribution area.
The coordination of the network is funded by the PROCEED project and will be managed for 2 years by The Nature Conservancy (TNC). Current information can be found on the website https://noraeurope.eu/.
In addition to research, an intensive transfer of knowledge into society is established. The oyster bank is used as a model to show and explain the special and important role of ecological key species and the importance of biodiversity and valuable ecosystem services.
An interactive online knowledge platform, exhibitions in the Erlebniszentrum Naturgewalten on Sylt, the Blue House Aquarium on Helgoland and the Zoo am Meer in Bremerhaven as well as specially developed educational materials for schools are planned to create a general understanding of the native species and the need of its reintroduction.
Furthermore, the oyster reef serves
- as a nursery and spawning ground for various fish species such as flatfish, gobies or pike
- to improve water quality: the oysters remove small particles and pollutants from the water due to their naturally high filtration capacity of up to 240 litres per day. This results in a local decrease in toxic algal blooms and improved interactions between the processes of the seabed and the water column ("increase in bentho-pelagic coupling").
- to support coastal protection by stabilising the sediment.
Ostrea edulis, as a biogenic reef builder, is a species in special responsibility. The biogenic reef serves as a settlement substrate for associated flora and fauna and is therefore a hotspot of biological diversity. It ensures important ecosystem services by providing habitat, nursing ground, food and protection for numerous invertebrates (such as sea anemones and crustaceans) and various fish species.
Supported by the Federal Agency for Nature Conservation with funds from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety within the Federal Programme for Biological Diversity (Bundesprogramm Biologische Vielfalt).