Exploring how 3D-printed reefs can benefit biodiversity

We’re collaborating with WWF Denmark to improve the resilience of the ecosystem in the Kattegat.

We’ve joined forces with WWF Denmark on an innovative project to explore how 3D-printed reefs can benefit biodiversity in the Kattegat.  

The Kattegat, a sea area between Denmark and Sweden, is experiencing a historically low cod population – threatening the health of the entire ecosystem.  

Through our partnership with WWF Denmark, we’ve deployed a dozen 3D-printed reef structures on the seabed between the wind turbines at our Anholt Offshore Wind Farm.  

Our hope is that these man-made reefs will create habitats for the cod to thrive and contribute to a healthier, more resilient marine ecosystem.

A delicate balance  

Years of overfishing, increasing oxygen depletion near the seabed, and habitat loss have all led to a decline of the cod stock in the Kattegat over the last 20 years.  

The cod stock is now alarmingly low – leading to a devastating impact on the entire ecosystem.  

As top predators, cod help maintain the marine ecosystem’s delicate balance by preying on other species, such as green crabs. 

With fewer cod in the Kattegat, the green crab stock grows, disturbing the ecosystem and negatively impacting other species. The crabs eat the seeds of eelgrass and snails that keep the eelgrass free from overgrowing algae.  

This creates a problem since eelgrass is itself of great importance to both biodiversity and the climate. It provides important habitats for marine life such as juvenile fish, it produces oxygen, and it stabilises the seabed.  

Crucially, it also very effectively stores carbon in its root network, preventing it from ending up in the atmosphere and contributing to the global temperature rise. 

Marine biodiversity in Denmark is under heavy pressure, and today there are 90 % fewer cod in the Kattegat than in 1990. Action is needed – and urgently. We must give nature and wildlife a hand, while trying to solve our climate crisis by expanding our renewable energy production at the same time. To solve the nature crisis, we must leave nature in better shape than before. That’s why we’re very excited that we, together with Ørsted, can test the new, unique 3D-printed reef structures here in Denmark for the first time.
Bo Øksnebjerg Secretary General, WWF Denmark

3D-printed reefs offer innovative solution 

The 3D-printed reefs we’ve deployed on the Kattegat seabed will increase the number of habitats for cod, hopefully with a positive effect on the species stock to, in turn, contribute to a healthier marine ecosystem. 

The biocompatible reefs made from natural materials, which will not be harmful to the surrounding environment, have a wedding cake-like appearance that allow space for the fish to swim in and out of hiding spaces.  

The structures will also provide hard surfaces and crevices onto which other organisms can attach.  

The 3D-printed reefs, which are about 1 cubic meter in size and weigh up to half a ton, vary in their exact shape to best imitate natural habitats.  

Our Biodiversity agenda 

Biodiversity is our life-support system – and its situation is critical. As a global leader in green energy, it’s our responsibility to make a positive contribution to both climate and nature.  

That’s why we’re committed to delivering an industry-leading goal of transforming all renewable energy projects into projects that create a net-positive biodiversity impact.  

This project around the Kattegat is the latest example of the solutions we’re exploring. Our ambition is that from 2030 at the latest, all new projects we commission must have a net-positive biodiversity impact.  

Building blocks for positive change

Climate change and biodiversity loss are two interconnected crises that must be addressed together. But we know we don’t have all the answers, that’s why we’re working with trusted expert partners to find and implement the best solutions.  

This project builds on our growing partnership with WWF Denmark.  

Last year we teamed up to install biohuts at the piers in the port of Grenaa in collaboration with the Port of Grenaa and the Kattegat Centre.  

Biohuts can be described as fish kindergartens as they provide vital protection to small fish. They provide a space for juvenile cod to seek shelter and food until they are large enough to swim out into deeper water.  

Together, the two projects offer new coastal habitats for cod at key stages in its life cycle.  

12 3D-printed reefs installed in the Kattegat

The 3D-printed reefs are also intended to complement existing boulder reefs that we established in connection with the construction of the Anholt Offshore Wind Farm in 2012.  

The objective with the installation of these stone reefs was to create attractive oases for marine species on an otherwise barren seafloor. Now, a decade after the stone reefs were established, they are teeming with life.  

Our hope is that the new 3D-printed reefs will complement the biohuts and boulder reefs, creating a healthier, resilient marine ecosystem for the Kattegat cod.  

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