At least half a million flat oysters will be introduced into the Port of Rotterdam on 2 September as part of a new pilot project. It is the trial run of an innovative method combining nature restoration and the installation of marine infrastructure, such as wind turbines, breakwaters and subsea cables. Before being installed at sea, the foundations of this infrastructure are covered with juvenile oysters. This pilot is part of a unique partnership between Van Oord and companies, research institutions, and nature organisations, working together to restore oyster reefs in the North Sea on a large scale.

The new method, known as the remote setting method, involves cultivating millions of oyster larvae in a dedicated hatchery before transferring them to a harbour or other location close to the sea. There, they are placed in shipping containers filled with seawater and rocks. In just a few days, the larvae attach themselves to the rocks and then grow into juveniles. The consortium is also investigating the influence of reef sounds. Do flat oysters use these sounds to find a suitable habitat for themselves? If so, then the sounds can be used to improve their chance of settling.

After a few weeks, the shipping containers are loaded onto vessels. The rocks bearing the juvenile oysters are released into the sea, where they seek their new habitat. If successful, this modular, flexible design will provide a cost-efficient method for reef restoration that can be applied anywhere and on any scale. By incorporating the oyster-bearing rocks directly into the engineering, construction and maintenance of wind farms, subsea cabling, breakwaters, platforms and other marine structures, the consortium members are combining marine infrastructure and large-scale nature restoration. Researchers will spend the next few months monitoring the survival and growth rates of the oysters. Next year, the consortium members plan to test the remote setting method again, at a TenneT cable crossing in open sea.

The push to develop this new method comes from an awareness that marine life in the North Sea is under pressure. Oysters form large-scale subsea reef structures by clustering together over the course of their lifespan. The reefs create a solid bedding full of nooks and crannies that are ideal habitats for numerous types of plants and animals. The oysters also filter the water, release nutrients and absorb waste products. All this makes them a vital factor in sustaining life in the North Sea. The North Sea’s oyster reefs have disappeared almost entirely, however, due to overfishing, pollution and disease. The remote setting method can make a significant contribution to regrowing the reefs.

The project draws on the expertise of the nine consortium partners: Wageningen Marine Research, Wageningen University & Research, ARK Rewilding Nederland, Stichting Zeeschelp, Waardenburg Ecology, Van Oord Ocean Health, TenneT, Port of Rotterdam Authority and De Rijke Noordzee (a joint venture between Dutch nature conservation organisations Stichting de Noordzee and Natuur & Milieu). The companies, public knowledge institutions and nature conservation organisations that make up the consortium have spent the past 3 years working together to refine the remote setting method.