The windmills on the North Sea are getting closer and closer, from the deck of the MS Tender. It’s half past ten in the morning. In the cabin of the speeding fishing boat, marine ecologists and divers speculate regarding what they will find during this long-awaited mission. Ropes full of mussels, rare off the coast of The Hague? Eggs from sharks and rays on the applied structures, a godsend for the animals that normally reproduce with difficulty?
“After centuries of large-scale fishing, nature in the North Sea has become impoverished,” says Marjolein Kelder, project leader of the expedition, a collaboration between environmental organization Natuur & Milieu and Stichting De Noordzee.
Two years ago, her researchers placed a number of artificial reefs on the otherwise rather barren and boring seabed, 12 kilometers from the coast, just in front of the Hollands Kust Zuid wind farm. The goal: to see if these kinds of structures become a breeding ground for marine life, similar to shipwrecks, which are hotspots for fish, anemones and other organisms, further enhancing biodiversity from there.
With a good result today, says Kelder, the hope is growing that artificial reefs can boost a rich marine life in wind farms. “Between windmills, bottom-disturbing fishing is not allowed,” explains marine ecologist Renate Olie. “Wind farms can become nurseries for the North Sea.”
Example function in Europe
Windmills at sea are sprouting like mushrooms from the seabed. Whether they are a curse or a blessing to the local ecology depends on how they are built. Where the Dutch government regularly falls short in nature policy – take the nitrogen crisis or the state of the soil – for example, it shows itself as progressive in the field of nature-inclusive wind farms at sea.
From the sunny deck, project leader Kelder explains that the Netherlands has an exemplary function in Europe. “Unlike the nitrogen crisis, where action was taken much too late, thanks in part to the North Sea Agreement, a great deal of attention is being paid to nature in the construction of wind farms.” Think of corridors for bird migration, fish-friendly building methods or alternative footstones with cavities where sea creatures can nest.
When the Netherlands opens a tender for wind farms, they do not choose a suitable energy company purely on the basis of the lowest costs, as in many other countries. “In the latest tender, the government opts for 50 percent on the basis of innovative nature plans.” In the race for major projects, energy companies sometimes spend as much as one hundred million euros on environmentally friendly construction. Oil notices that. “Companies are looking for ecologists en masse. I often get offers for a job.”
Cloudy water
At the briefing on deck, dive leader Floor Driessen tells her team what the intention is today. Step one is to recover the stone ReefCube, the structure that was placed 3 meters deep two years ago, a kind of pyramid of 3 by 3 meters of stone cubes with holes in them. Sounds easy: the coordinates are written on a whiteboard in the bridge.
But during the briefing it turns out that just finding it is a difficult task. “The water is so murky that you can only see an arm’s length in front of you,” explains diver Ben Stiefelhagen. Partly because of the sand fog underwater, partly because algae are in bloom.
Diver and ecologist Joost Bergsma made two dives today, each lasting 42 minutes, at noon and at six o’clock, when there is little current. Once the artificial reef has been found, step two follows: taking photos, so that it can be determined on board which organisms are living there. Waves today are ‘only’ half a meter high, yet Driessen apologizes during her explanation and rushes to the edge of the ship. Seasick. “Part of North Sea diving”, Olie laughs.
How do you measure progress?
The fact that nature restoration in the North Sea is more difficult to organize than in forests and heaths, for example, became apparent during the expedition. The plans are grand. Kelder says that the National Postcode Lottery paid 8.5 million euros for De Rijke Noordzee – the project that focuses on opportunities for wind farms. One goal is to recreate the original oyster beds that disappeared 200 years ago between wind farms. But how, and how do you measure progress?
During Bergsma’s first dive, the ecologists on board eagerly await a message from the small diving boat. After half an hour, Bergsma has not yet found the pyramid, due to the poor underwater visibility. After three quarters of an hour he comes up exhausted, without result. “Setback,” says Olie.
Floating around for hours
In the hours that follow, the atmosphere on board is kafkaesque. A rented fishing boat with a crew of regarding fifteen people bobs around for hours, waiting for a small underwater structure to be found to see if anemones grow and crayfish live there. Very expensive and time-consuming, and for what exactly?
Crew members with a more traditional skipper background have their doubts. Piero Tundo, from the ship’s galley, is “not a fan” of the artificial reefs. The North Sea has become a lot cleaner in recent decades, he says, now that skippers no longer dump all their rubbish and oil into the water. “Nature will heal itself.”
The 69-year-old pilot Dirk Venema also shakes his head over the railing. “Waste of money,” he says. In any case, he has “an opinion” regarding the government’s nature policy. “My parents were farmers.” Tundo also thinks that the environment is a ‘hot topic’ and that is why millions go to feel-good projects like this.
Waiting for his second dive, Bergsma counters that. He emphasizes that nowadays there are almost no cod left, and that other animal species have also practically disappeared. A richer North Sea offers benefits for many other species, birds and fish. Compare artificial reefs in wind farms with a forest in an open plain, where animals find shelter and food. Kelder: “Climate change is a threat, but if the ecosystem is healthy, the sea can better cope with those blows.”
Diver Bergsma jumps into the water for a second time with an oxygen tank. The team waits expectantly in the cabin. After twenty minutes, the audio connection on board sounds. “Joost has found structure.” A team member of De Rijke Noordzee jumps and shouts, the captain jokes that it’s time for champagne.
“It was completely full of vegetation,” Bergsma says with satisfaction once on board, when he pulls the diving mask off his head. “Lots of penpenschaft”, he explains tiredly, a hydropolyp, family of jellyfish, with a pink top. “Lots of swimming crabs at the bottom, but no fish.”
A little later, the four ecologists are sitting expectantly behind a laptop in the cabin, on which Bergsma uploads his GoPro images. The description of what he saw does not immediately sound like a great diversity of species, with the pen shaft and gargle pipe polyp predominating in particular. Sometimes more species can be discovered on the video images.
Olie is already relieved that the structure is still there following two years, well and good. And yes, although there are no mussels to be seen on the ropes made for this purpose, this can be radically different in the summer.
Nipple eggs
The laptop screen shows greenish hazy images that are reminiscent of Titanic, filmed from the diver’s head. The richly vegetated construction appears, the wispy pen shaft is reminiscent of tropical coral reefs. Crabs and crayfish crawl through it. “See that sea urchin!” says Bergsma. “Eggs from the nipples”, Olie responds enthusiastically. She was already hoping for exotic-looking underwater slugs.
She has a “slug addiction,” she admits. More species are expected to be in the holes, not dirty brown beasts, but magical-looking sea creatures that might come straight out of a David Attenborough documentary. In addition to sea snails, she also counts a velvet swimming crab, a sea apple and a starfish in the images. “Much more biodiversity than I expected.”
After a downer in the morning, the ecologists can go to bed satisfied in their cabin. The ship is back in the harbor of Scheveningen. In the following days they will look for three more structures, which they will hopefully find immediately. One is partly made with tree trunks and old oyster cages, because cement is not really durable.
Bergsma is ready for his next dives. He admits that he does not yet know how much effect these types of structures have in the gigantic sea, whether it only provides biodiversity on the artificial reef itself, or also in tens of meters around it. But the only way to find out is through this kind of research. Kelder: “If you really want to place many of these types of structures between wind turbines, it is easier and cheaper to conduct research on a test site like this than between wind turbines, where diving is not allowed.”
In the coming years, the pressure on the North Sea will continue to grow, with solar at sea, CO2 storage infrastructure and green hydrogen. “We have to keep looking at the risks for nature,” says Kelder. “And also keep looking for opportunities for nature that you wouldn’t have had without this infrastructure.”
Europe is watching with interest. “Recently I was at a conference in Ireland,” says Kelder, “where wind farms were only concerned with limiting risks, for example for birds. I came to tell you how wind farms can also yield new nature.”
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