(Ostend) To combat coastal erosion, Belgium is testing a solution: the creation offshore of a natural mussel reef, likely to curb the harmful effects of the powerful currents of the North Sea while developing biodiversity.
This scientific experiment, the result of research by the Flemish institutes Ilvo and VLIZ associated with Belgian firms specializing in offshore construction, was carried out for six years a few kilometers offshore from the La Panne station, near the French border.
Its results were presented in October in Ostend, the Belgian stronghold of marine studies. The test project is now waiting to attract governments who will be able to develop it on a large scale with the necessary funding.
The principle is to install ropes at the edge of deep water on which mussel larvae can cling.
Nature then takes over.
The growth of molluscs clustered together on vertical lines will gradually provide a natural barrier to currents, in this intermediate space between low and deep water where the sand is swept away with force.
Second stage: as soon as they become too heavy to be supported by the rope, these clumps of mussels fall to the bottom of the water on their own, giving birth to a new ecosystem.
“A habitat for all kinds of living species develops around the mussels, and it is the fact that it falls to the bottom that will create the reef,” underlines Alexia Semeraro, researcher at the Research Institute for Agriculture , fishing and food (Ilvo).
“Biological protection lines”
A “biogenic reef” which amounts to stabilizing sediments suspended in the water on the ground, she continues. And therefore to limit erosion in a maritime area known for its powerful currents and waves sometimes exceeding several meters high.
“We offer a solution for the challenges to come,” argues Tomas Sterckx, of the Belgian multinational Deme, who brought his expertise in maritime infrastructure to the project.
He explains that with climate change the Belgian coast is exposed to the risk of more and more frequent storms of increasing intensity.
What he calls “underwater biological protection lines”, built with ropes using aquaculture techniques, will not replace the addition of sand to reinforce the coastline.
But “this first line of defense against storms” is one of the keys to the fight against erosion, insists Tomas Sterckx.
Off the coast of La Panne, the buoys and anchors which attached the ropes to the two experimental reefs created since 2017 have now been removed. This involves respecting the requirements for protecting fauna and flora in the Natura 2000 classified area.
In their laboratory in Ostend, Ilvo biologists are already preparing the recipes for the next “natural buffers” that they intend to test, based on algae, sea grasses or tube-dwelling sand worms.