France REEFOREST – REstoring the European Flat Oyster Reefs & their Ecosystem Services on the French coasT

The progress report of the REEFOREST project is now available online. It presents the main results obtained in France on the optimization of the flat oyster restoration methodology since 2022. This project is led by Ifremer & OFB (French Office for Biodiversity) in collaboration with Natura 2000 managers and professionals from the shellfish and the fishing industries. The project calls also on various specialists in marine ecological restoration (e.g. BESE, SEABOOST, CorailArtefact…). Some experiments are also made in collaboration with other NORA partners.

Bringing out the settlement substrates in the Bay of Brest.

The substrate cones are overgrown with native oysters, sea anemones, sponges, Hydrozoa and other sessile invertebrates after just a few months.

The main pilot site for REEFOREST is located in bay of Brest, in the heart of a former oyster bed. The advances made by REEFOREST are increasingly consolidating the methodology for restoring the flat oyster and its habitat, particularly in sensitive areas (Natura 2000 type). This methodology is based on the tryptic: “Where, When & How to restore”.

The choice of restoration site (“Where to restore?”) involves taking into account historical, ecological, hydrobiological and geomorphological criteria. Reeforest is revisiting these criteria at the Brest site.
Once the site has been selected, the next step is to choose the best time of year to restore a site (“When to restore?”). The success of the restoration depends crucially on the choice of this moment. Substantial analysis work on long time series has been carried out in REEFOREST to provide a set of keys for determining this ideal time. Some of the indicators proposed here can even be used to anticipate the new breeding season.
To answer the third question, “How can we restore?”, REEFOREST offers a range of restoration tried and tested methods from the use of concrete blocks for artificial ecosystems to bio-inspired soft methods for sensitive sites (Natura 2000). The latter method, which is very promising and environmentally friendly, has been and will continue to be the focus during the rest of the project.

Field Trials with different settlement substrate materials and structures.

The settlement cone is positioned on a wooden stick to avoid that crabs and other bottom-living predators feed on young oysters.

The artificial structure is overgrown with oysters and other sessile invertebrates.

Another part of the REEFOREST project aims to improve the evaluation of the main ecosystem services of populations undergoing restoration. Particular emphasis is placed on filtration and biodiversity support services. First results concerning these both services are given in the report. The last objective of REEFOREST is working on the application and transfer of the methodology to other sectors of interest. REEFOREST’s achievements are currently benefiting 3 other brand new projects in France : REHPAR, CLIMAREST and REFONA.