Offshore wind turbines are transforming the marine environment, according to a report

Offshore wind turbines are transforming the marine environment, but knowledge remains limited on many aspects of their effects on biodiversity, according to a collective scientific assessment presented a few days ago.

Led by Ifremer and the CNRS, this expertise "offshore wind turbines and biodiversity" constitutes "the most complete overview to date" on the subject, assured Thierry Dauxois, CEO of the CNRS during a press conference.

Twenty-five experts worked on this report of more than 1.000 pages, analyzing a corpus of 411 scientific articles. "We left nothing out," assured Cédric Bacher, a researcher at Ifremer.

Scientists have listed ten "pressures" exerted by offshore wind turbines, from noise and collisions with birds to changes in the habitat of fish and other crustaceans.

Wind turbine foundations, for example, create a well-documented "reef effect" by attracting numerous marine species that colonize them. One of the articles analyzed reports one to two tons of mussels clustered on the submerged base of a single wind turbine in a Belgian wind farm.

"These mussels are surrounded by a whole range of species, forming a new community, with anemones, crabs, but also fish that come to feed on them," described Nathalie Niquil, research director in marine ecology at the CNRS. "All this leads us to believe that there is a change on the scale of the entire ecosystem."

Other pressures with well-documented effects include the risk of collision with seabirds or the modification of the behavior of porpoises and fish, due to the noise emitted during the construction of wind turbines.

"Biodiversity is changing because of wind farms, but also because the wind farms are located in a landscape that has already been transformed," Mr. Bacher pointed out. "These transformations are lasting and likely if there is a massive, long-term deployment of offshore wind power."

By 2050, France has set itself the objective of reaching 45 gigawatts (GW) of offshore wind power, compared to 2 GW currently.

Scientists have taken a neutral stance on the documented effects, refusing to label them as positive or negative, as the same effect can "be interpreted differently depending on the context," according to Ms. Niquil.

They also pointed out the numerous gaps in the scientific literature on certain understudied areas (chemical emissions, artificial light, etc.) and regarding the cumulative, long-term and large-scale effects of wind turbines.