Biologists compared a recent survey of fish at Horns Rev 1 with an 8-year-old study conducted prior to construction of the 160-megawatt installation, and found most to be thriving. Some species actually increased in number.
Whether the peaceful coexistence of fish and giant turbines at Horns Rev 1 has any relevance to other wind farms is unknown, since conditions at any particular installation tend to be unique. But it does suggest that there is nothing inherently incompatible between marine life and offshore wind power – while pointing to some positive influences.
Located in the North Sea 14 km west of Denmark, the turbines at Horns Rev 1 are sunk deep into the seabed in shallow water no more than 20 meters deep. Surrounding the pylons are large piles of stones built to prevent sand erosion at the bases of the turbines.
Scientists found that the stone structures serve as artificial reefs, providing inhabitants with an abundant supply of food and shelter from currents – while attracting new species that prefer a rocky sea floor.
“Species such as the goldsinny-wrasse, eelpout and lumpfish which like reef environments have established themselves on the new reefs in the area — the closer we came to each turbine foundation, the more species we found,” says DTU biologist, Claus Stenberg.
Of particular interest were how species that live on the fine-grained sand banks beneath the wind farm would be affected – including one of the most important fish to the Danish fishing industry, the sand eel
“The study shows that wind farms have not been a threat nor of particular benefit to the sand eel. The sand eel is dependent on the fine sand, in which it buries, to live, and the mills did not affect either the sand grain size on the bottom nor had any impact on the number of sand eels,” said Stenberg.
“Horns Rev is situated in an extremely tough environment with strong wave action, which means for example that seaweed forests, together with the small fish that live in them, cannot establish themselves. We would therefore expect the positive reef effects to be even greater still in a park located for example in the more sheltered Kattegat,” he continued.
The area around the Danish wind farm has been closed to fishing since construction began, making it something of a mini protected area.
“Our studies suggest that the Horns Rev 1 is too small to function as a true marine protected area (MPA), because over their lifecycles the fish utilize a much greater area than just the wind farm. But presumably several parks located close to one another could have a combined positive effect on spawning and the survival of fish fry, as wind farms which are located downstream of each other can act as a kind of dispersion corridor for eggs and larvae,” said Stenberg.