Brecht Stechele
Ghent University, Gent, Belgium
The flat oyster (Ostrea edulis) is indigenous to Europe and once formed large reefs spreading out along almost all European coastlines. For centuries, these oysters supported flourishing ecosystems and supported oyster fishery. Roman literature describes the collection of oyster spat (attached juveniles) from rocks and grow-out in ponds. Unfortunately, multiple factors, such as overfishing since the 18th century, cold winters in the 1960s and outbreaks of disease (e.g. Bonamia) in the 1980s devastated wild oyster reefs resulting in collapse of the stock. This, in turn, made both harvesting of wild stocks and aquaculture of O. edulis impossible in the most traditional rearing areas. Recently, renewed interest in the flat oyster has boosted the number of restoration and aquaculture projects throughout Europe.
In recent years several policy measures have opened possibilities for restoration of flat oyster reefs. The Belgian marine spatial plan 2020-2026 excluded bottom fishery from large areas assigned to offshore energy generation. Some of these areas overlap with the historical distribution of flat oyster reefs and are already protected under the Natura 2000. Additionally, the Belgian state aims to restore the gravel beds, the historical habitat for flat oysters, framed within the Belgian implementation of the Marine Strategy.
Even though natural colonization of substrate by flat oysteris preferred, introducing juveniles or adults can facilitate the restoration process, thereby increasing restoration success. The presence of a reproductive oyster population is therefore a condition sine qua non. There are only a few wild live specimens in the Belgian part of the North Sea and the larval presence can be increased by culturing flat oyster though restoration projects.
Within the H2020 project on ‘Multi-use platforms and co-location pilots boosting cost-effective, eco-friendly and sustainable production in marine environments’, UNITED, five multi-use pilot demonstrators will provide evidence that the development of multi-use platforms or co-location of different activities in a marine and ocean space is a viable approach for oyster restoration. The Belgian pilot demonstrator aims at boosting reef creation through native oyster aquaculture in the offshore wind farms. Viable aquaculture systems will be developed for oyster cultivation in high energy offshore environments while scouring protection material, used to stabilize wind turbine pillars or underwater cable crossing, will be upgraded to support larval settlement and reef building. An important output of this project will be the development of modelling tools for restoration. A metabolic growth model for flat oyster will be coupled with a population model and a larvae distribution model. These tools will allow evaluation of shellfish restoration scenarios.
Figure 1. An illustrative overview of the Belgian pilot demonstrator within the H2020 UNITED project
For further information, contact Brecht Stechele (brecht.stechele@ugent.be), see also: https://www.submariner-network.eu/united
