A few miles out into the Atlantic Ocean off the coast of Portugal, there is a collection of three floating wind turbines that generate electricity.
The Windfloat Atlantic facility is notable as the world’s first commercial-scale semi-submersible floating offshore wind farm (it went live in 2020).
Most of the debate regarding wind power in this type of ocean setting has centered upon the amount of electricity produced by turbines at sea. Building and maintaining these structures far offshore presents significant engineering challenges.
Attention has also focused on their visual impact and whether they alter ocean views for people onshore.
But researchers studying the waters around one floating wind farm ended up focusing on something else entirely beneath the surface below.
What researchers found beneath the turbines
However, while studying the marine environment in the vicinity of the turbines, scientists monitoring marine life discovered another significant issue related to marine biology.
Researchers conducted environmental monitoring at WindFloat Atlantic for more than eight years.
During that time, species including octopus, rays, and sole were observed in higher abundance within the project area than in comparable surrounding waters.
This observation raised an interesting question:
Why would marine life congregate in much greater numbers around floating wind turbines?
There are three large floating wind systems located about 20 kilometers offshore in waters averaging about 95 to 100 meters in depth.
As noted above, the monitoring program covered a wide range of environmental factors associated with the project.
These included plankton, fish, octopus populations, marine mammals, seabirds, bats, underwater noise generated by the turbines, and biological growth occurring on the structures themselves.
The study drew upon data collected through regular government-mandated environmental monitoring programs. Researchers also conducted independent environmental assessments to better understand how floating offshore wind facilities interact with marine biodiversity.
The numbers inside the project area stood out
Over 270 species were identified within the WindFloat Atlantic project area during the monitoring period. Among them were 52 fish species, five marine mammal species, 33 bird species, and three bat species.
These findings were based on eight years of environmental monitoring conducted at the project, according to Ocean Winds.
The results were summarized in a report from Blue Grid, Marine and Environmental Sciences Centre, Faculty of Sciences of the University of Lisbon, and the Polytechnic University of Leiria.
Natural seasonal and annual environmental changes remained the primary influence on marine communities in the area. Even so, they found some differences between the marine community inside the wind turbine complex and similarly situated control sites outside the project boundaries.
One of the major differences noted was an increase in abundance of both octopus and fish species inside the project area.
Higher abundance was also observed among elasmobranch communities, including rays.
Abundance was generally found to be higher within the study area than in surrounding comparative areas.
Despite this general trend, however, researchers found no evidence of adverse impacts on lower trophic level organisms, such as phytoplankton and zooplankton. On the contrary, higher abundance was observed among some higher trophic groups, including fish, octopus, and other invertebrates.
Additionally, researchers determined that the installation of the WindFloat Atlantic facility had not disrupted normal ecosystem function.
Why was more marine life gathering here?
Researchers explained that the “refuge effect” was linked to restrictions on fishing and vessel traffic within the wind turbine area.
The “reef effect” was linked to underwater structures providing habitat and surfaces for various types of marine animals to colonize.
Monitoring documented marine growth on the turbine platforms, including kelp, barnacles, mussels, sea stars, anemones, and other species. Together, these conditions appear to create a refuge and feeding area for marine wildlife.
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