Hywind Tampen’s anchor chains are becoming marine-life corridors, with crabs, anemones, sea stars and shrimp clustering along steel
A chain from one of the floating wind turbines was resting more than 800 feet beneath the surface in the mud of the North Sea.
In March 2026, an underwater robotic vehicle trailed this chain made of steel for several hundred yards.
Squat lobsters were commonly seen.
Hermit crabs with anemones on their backs, shrimp, starfish, fish, and other creatures found rarely in the surrounding normal seafloor environment were also common.
Hermit crabs with anemones on their backs, shrimp, starfish, fish, and other creatures found rarely in the surrounding normal seafloor environment were also common.
At Hywind Tampen, the equipment that keeps the floating turbines upright might be helping to create a new habitat, too.
The chain is part of a much bigger machine
Hywind Tampen is made up of 11 floating wind turbines located about 87 miles out in the Norwegian part of the North Sea, where the seabed lies between 850 and 980 feet below the surface.
As of its official opening in 2023, Equinor has estimated the capacity of Hywind Tampen as 88 MW and described it as powering the Snorre and Gullfaks offshore oil and gas facilities.
However, the wind turbines sit atop floating concrete structures, not on foundations drilled directly into the seafloor.
Therefore, the anchors and chains must prevent the force of wind, waves, and currents from drifting the structures.
And the chains extend hundreds of feet down into the sea until they reach suction anchors on the bottom.
An underwater robot followed the hardware
This happened on cruises in December 2025 and March 2026 conducted by the Norwegian Institute of Marine Research using ROV Ægir.
When collecting material on the reef effect, scientists filmed trajectories starting from suction anchors and running 1,150 to 1,640 feet further along anchor chains towards turbines.
In addition, they filmed control transects over muddy bottoms at some distance from the chains.
Comparison is the key thing.
The point was not to find out if there were animals in the neighborhood of Hywind Tampen.
Animals lived here anyway.
The goal was to compare the seabed connected with floating-wind equipment and not connected with it.
The crustaceans went toward the chain
A few species were more abundant in the controls.
In the absence of chains, irregular sea urchins and calcareous tube-building bristle worms were abundant, while sea urchins were abundant in control transects.
Most of the other species exhibited migration to the contrary.
Squat lobsters, hermit crabs, sea anemones, shrimp, sea stars, brittle stars, and hydrozoans were found to be abundant in the chain transects.
Sea cucumbers, whelks, and fish were also observed in abundance at chain transects.
During one of the March transects towards the turbine Hy10, squat lobsters were found abundant along the chain, while hermit crabs were observed with anemones.
Ling, tusk, shrimp, and some species of sea stars were observed there.
Steel changes what the seabed offers
Muddy ground and a metal chain are two distinctly different habitats.
The surrounding substrate is soft and relatively homogeneous; in contrast, the presence of the wind farm structures creates solid substrates, edges, refuges, and attachment sites for the organisms.
This phenomenon is known as the reef effect by marine ecologists.
However, it is too early to say what caused this increase in particular.
Nor did every species accumulate around the wind farm, according to Cruise no. 2025001020 and 2026001021 from the Institute of Marine Research Norway.
Fish acoustic survey transects revealed inconsistent results during December, as some of the transects experienced decreased density of fish within the Hywind Tampen facility, while others exhibited an aggregative effect.
The pattern was not observed during March, indicating lack of preliminary evidence for attraction or repulsion by the wind farm of the fish population.
Seven transects keep the conclusion narrow
The most critical figure in the report is probably the number seven.
Technical issues and the weather ensured that scientists could only conduct seven of the 12 intended ROV transects, while technical issues with the sediment core meant that much of the intended sampling was impossible.
But this does not make this report proof that floating-wind anchor systems help to increase biodiversity in the North Sea.
This is just a hypothesis from one floating wind farm operation.
This makes the underwater photos even more valuable for analysis.
The Hywind Tampen farm was designed with chains capable of transferring great force from the movement of the turbines to the seabed.
Three years after the wind farm went into full production mode, scientists are discovering another role developing within the same steel.
For squat lobsters, hermit crabs, shrimp, and anemones, part of the anchoring system is becoming less like an engineering structure.
Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.
