When huge blocks of concrete are thrown to the bottom of the sea, we can think that whoever is doing it is looking for a territorial conflict or even to ruin the ecosystem, as It was already seen in Gibraltar in 2013 in order to prevent fishing. However, on the coast of the United Kingdom, this same action of throw concrete blocks It has become the spearhead of one of the most ambitious bioengineering and ecological restoration projects in Europe, despite being contradictory.
The objective. The objective of throwing these blocks is to bring reefs back to life of native North Sea oysters, lost more than a century ago due to overfishing, pollution and the destruction of their habitat.
Heavy engineering. At first glance, it seems simple to take some concrete blocks and throw them over the side of a boat. But in reality the 20 blocks recently deployed off the coast of Tyne and Wear are actually pieces of green high-tech.
And it’s no wonder, because have been developed ARC Marine under the name Reef Cubes and made with a special material called “Marine Crete”. Furthermore, they are not small at all, because each of these cubes weighs six tons and measures one and a half meters high.
Why this weight? This initiative promoted by the Zoological Society of London (ZSL), the Wild Oysters project and Groundwork, leaves nothing to chance, since the fact of launching these heavy masses of concrete is explained by the British climate.
In the previous phases of this project, the team encountered devastating storms that destroyed all restoration attempts. That is why these six-tonne masses ensure that the violent ocean currents and waves of the North Sea do not move the structures even one centimeter so that they can develop their final objective.
Its usefulness. The magic actually happens on the surface of the block, as these cubes are not entirely smooth, but are designed with complex rough textures and artificial pores that perfectly mimic natural marine surfaces. These automatically become the perfect anchorage for life to thrive and an ideal refuge for fish and crustaceans.
The role of oysters In addition to the roughness, 4,000 native European oysters have been placed inside each of these 20 immense cubes thanks to the efforts of 190 local volunteers. And it makes all the sense in the world, because beyond their great gastronomic value, oysters They are the great “purifiers” of the ocean.
To give us an idea, a single adult oyster is capable of filtering up to 200 liters of water per day. In this way, when they feed they eliminate pollutants, nitrogen and excess nutrients, radically improving the quality of coastal water and allowing sunlight to penetrate deeper, which in turn stimulates the growth of marine flora. In short, these blocks act as a new ‘home’ for the animals that live on the seabed, but also as a way to clean their environment.
It already gave results. The robustness of using thousands of tonnes of concrete on the seabed has already been tested in Scotland with great success, and now this project is just the beginning of what is to come. That is why, while these artificial reefs begin to filter millions of liters of water daily in the north, other projects are taking note to scale the idea to titanic proportions.
In Norfolk, initiatives such as Oyster Heaven and Norfolk Seaweed are already planning the deployment of 40,000 clay “Mother Reefs” by the end of 2026. Their goal is to house 4 million juvenile oysters, which would officially be crowned the largest restored reef in all of Europe. In this way, throwing blocks into the sea has gone from being a technique to create conflicts between regions to being able to recover part of an ecosystem.
Images | Robert Katzki Nicolas Arnold
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