REEFGLUE for bioinspired reef rehabilitation

The European flat oyster (Ostrea edulis), native to the North Sea, provides a multitude of ecosystem services, including enhancing water filtration and sustaining biodiversity. Continuous exposure to overexploitation has led to massive declines in population stocks. In addition, habitat destruction by bottom-trawling fisheries have decimated substrate availability required for larval settlement, thereby limiting population recovery. At present, multiple initiatives aim to restore flat oyster habitats by introducing artificial settlement substrates. These substrates are often made of concrete, of which the production is unsustainable. Recently developed bio-inspired adhesive, so called Reefglue, can replace concrete and serve as a bio-concrete filled with recycled shellfish material. Pilot research has shown that oyster larvae are capable of settling on this bio-concrete, showing the potential as a more sustainable alternative to regular concrete when creating artificial reefs. We propose to study the attraction- and settlement success of oyster larvae on this bio-concrete. Furthermore, the physical and ecological performance of bio-concrete within the North Sea environment will be studied. In addition to the provision of settlement substrate, restoration often includes the release of hatchery-produced spat or translocations of adult individuals. Although these efforts are thought to be effective in stimulating population recovery, the impact on the genetic diversity remains unknown. Genetic diversity has a large influence on a populations ecological resilience. When kick-starting oyster reef rehabilitation it is imperative to take the genetic background of the introduced individuals into account to preserve ecological resilience. In this research, an approach will be developed to study population genetics with non-invasively collected environmental DNA (eDNA). Gaining insight in population genetics enables the preservation of genetic diversity of existing/introduced populations in restoration programs. Both the provisioning of bio-inspired concrete and of a genetically diverse source population will enable kickstarting ecologically sound oyster reef rehabilitation and preservation of their ecosystem services.