Wired into 130 feet of North Sea water between Denmark and Britain, dozens of steel monopiles were built to catch wind, and the animal pressing closest to the steel in a July 2025 water sample was one that no turbine engineer ever put in a risk assessment
The water around it looks like any other stretch of the North Sea: gray, cold, and apparently empty. Steel meets salt at the waterline, and somewhere below, in water that drops to 130 feet, the foundation of a wind turbine sits on a sandy seafloor that was featureless for centuries. Nobody designed what came next. Nobody wrote it into the construction plan. And when scientists finally lowered a water sampler beside the steel and analyzed what they pulled back up, the name on the results was not one any turbine engineer had listed in a risk assessment.
A desert that suddenly had a mountain
The North Sea floor, across most of its southern half, is a vast plain of soft sand. There is almost no hard surface anywhere, which means almost nothing can attach, and almost nothing does. For filter feeding creatures that need something solid to grip, the open seabed might as well be concrete poured smooth.
The arrival of a steel monopile, a cylinder sometimes wider than a bus and driven dozens of feet into that sand, changes everything about the local physics of survival. Monopile foundations provide vertical surfaces where mussels, barnacles, and other colonizing organisms readily attach. These colonizing species form the base of a complex food web, attracting fish and crustaceans that pull the food chain upward through the water column. Within months of installation, a bare steel post becomes something closer to a coral head, bristling with life.
Future projects could deliberately design their scour protection to maximize reef habitat, essentially building a fish nursery into every foundation specification.
What the numbers behind a single turbine reveal
By 2025, key ecological measures such as species richness, diversity, and trophic structure at wind farm foundations showed no significant difference from established, purpose built artificial reefs. A separate review of benthic communities on hard substrate found that wind farm foundations could lead to a doubling of species richness and an order of magnitude increase in species abundance per square meter.
That second figure is not a rounding error. It is the difference between a desert and a forest. The reef effect has been documented at wind farms from Denmark to the English Channel, and the direction of the data has not changed in more than a decade of monitoring. Each new farm adds another data point to a pattern that is starting to look less like a happy accident and more like a reliable ecological rule.
Seals learned the route, then something bigger followed
Scientists now routinely document marine creatures visiting or living within offshore wind farms, ranging from microscopic oyster larvae to gray seals, sharks, and porpoises. The seals arrived first at many sites and quickly figured out something no human observer had anticipated: the turbine array functions as a reliable hunting grid.
When a gray seal tags a monopile as a feeding stop, it is reading the food web correctly. Mussels coat the steel, small fish hover in the mussel shadow, and the seal works the column the way a human angler works a known snag. Researchers tracking individual seals with GPS found animals traveling between turbines in straight lines, as if navigating a mapped route. No wild seal had been observed moving like that before wind farms existed. The question animating marine biologists was whether those animals represented genuine population growth or simply a reshuffling of creatures that would otherwise be somewhere else.
The animal in the water sample that stopped the conversation
A Wageningen University study published in 2025 found evidence of shark and skate species frequenting offshore wind farms in the North Sea. Researchers detected their DNA in water samples taken from several Dutch wind farms using environmental DNA analysis, a technique that works by filtering seawater for genetic traces that living animals shed continuously through skin, mucus, and waste. If a creature passed through recently, the water remembers.
Sharks and skates are apex predators in the North Sea food web. What the eDNA results confirm is that the animals are actively choosing the wind farm environment, pressing close enough to the steel that their genetic signature saturates the water column. Annemiek Hermans, the lead researcher and a PhD candidate at Wageningen, said it was like “finding a fingerprint in the water,” adding: “Even if you don’t see the shark, the DNA tells you it’s been there.” For a fishing industry that has watched North Sea shark and skate populations shrink for decades, the finding carries unexpected weight. A structure built to harvest wind is, it appears, also rebuilding a food web, and the same operator behind South Fork Wind is now embedding batteries alongside turbines to extend the value of every rotor turn.
What the industry does with an accidental reef
The discovery places wind farm developers in an unusual position. Their permits were written for electricity, not ecology. Now marine biologists are arguing that foundations and the scour protection rock piled around them should be treated as habitat, not just infrastructure, and that decommissioning rules requiring their removal may be doing more harm than good.
Hermans cautioned that fishing should be avoided entirely in such locations if wildlife is to thrive, warning that “if we start allowing bottom trawling in these areas, we risk losing the very protection the zones may offer.” That regulatory gap is now a live debate in the Netherlands, the United Kingdom, and Denmark, where the oldest offshore wind farms are approaching the end of their licensed lives. Future projects could deliberately design their scour protection to maximize reef habitat, essentially building a fish nursery into every foundation specification.
Some developers are already testing textured concrete collars that favor mussel attachment from the first week of installation. The turbine that generates clean power above the surface and rebuilds a collapsing food web below it is no longer a thought experiment. In the North Sea, it is already standing.
Hugo is an engineer with strong technical expertise. Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.
