Will the Belgian Oysters flourish on our shores?

November 2020: a busy month at the Belgian pilot!

Our Belgium waters used to house reefs of European flat oyster (Ostrea edulis). Such reefs provide a valuable habitat supporting a unique marine biodiversity, but also provided a luxury seafood for our cuisine and culture. However, overfishing since the 19th century and the occurrence of diseases (such as bonamiasis) in the 1980s devastated these wild oyster reefs.

The opportunity

Belgian offshore wind farms offer a unique environment to restore oyster reefs and develop aquaculture. Bottom fishing is not allowed in wind parks – and oyster reefs would thus not be damaged. At the same time, the hard substrate used as scour protection around wind turbine poles provide a substrate for oyster larvae to settle on and initiate natural oyster reefs. The UNITED project aims to culture the initial oyster stocking material to allow the natural reefs to develop and, in the longer term, natural oyster reefs would provide oyster larvae to the aquaculture sector.

UGent and partners accept the challenge

Co-location of restoration and aquaculture in wind parks looks like a logical choice, but we are still far from its large-scale application. The distance from the coast, operation and maintenance of the structures needed for restoration and aquaculture production, and the harsh sea and weather conditions in the North Sea complicate implementation. Optimal growing conditions of flat oyster are quite specific, and this makes offshore aquaculture and restoration very challenging. The selected scour material must fulfill the technical requirements imposed on scour material in general and, at the same time, it should create an attractive habitat for oyster larvae to settle.

Research and development update

During the summer the Belgian UNITED team deployed aquaculture structures for flat oyster designed by UGent and Brevisco and produced by Brevisco, and restoration tables designed and produced by Jan De Nul Group. Now, it was time to retrieve these structures for a first evaluation (Figure 1). We sailed off in November to collect data and observe the first results, under a bright autumn sun and joined by the camera man of No-Office, to capture our every move (Figure 2).

The team investigated the settlement of wild oyster spat (Figure 3), robustness of deployed systems, differences in flat oyster settlement between multiple nature-inclusive scour protection materials, efficiency of decommissioning methods, labelling techniques, and differences in biodiversity between substrates. A labour and time consuming job, so the entire team was present to collect the data (Figure 4). The aquaculture structures were transported to the Marine Station Ostend (Flanders Marine Institute, to increase survival of settled oysters while being counted. The results are currently being processed.

The knowledge gained from these first captivating sea missions nearshore are crucial for the selection of the best performing materials and methods to be applied in the spring of 2021 in an offshore wind farm of Parkwind.

For more information on the project, please visit the websites of Horizon 2020 UNITED project and UGent. The work done at the Marine Station Ostend makes use of resources, facilities and/or services provided by Flanders Marine Institute and the Marine Biology Research Group of UGent as part of the Belgian contribution to EMBRC-ERIC.