Provence Grand Large monitoring records frequent dolphins and tracks seafloor community changes
Nineteen kilometers from the coast of Provence, France, research boat travels into the Gulf of Fos, with crew members looking out for something in the water, their notebooks ready. Soon enough, the dolphins show up — 35, at times 38, at other times even 40 on each voyage. This is now an established pattern.
But underneath all this, a question that remains unanswered lingers: what exactly is going on with marine life when three massive floating wind turbines call this Mediterranean deepwater home?
A pilot farm unlike any other in France
Provence Grand Large reached full commissioning on June 5, 2025 — making it simultaneously France’s first and the Mediterranean’s first floating offshore wind farm. Three turbines, built by Siemens Gamesa, now stand 17 kilometers off Port-Saint-Louis-du-Rhône, generating 25 MW of capacity and supplying electricity equivalent to the annual consumption of 45,000 homes.
When a dolphin echolocates near a turbine platform, that sound is captured and stored, building a behavioral record that will only grow more valuable with time.
The engineering which is outstanding here is the fixity of the turbines themselves, since they are not installed on any fixed foundation but instead rest on tension leg platforms, a technique that is borrowed from offshore oil drilling rigs. This technique was invented by SBM Offshore and IFP Energies Nouvelles and is the first ever used in floating wind. The project has received financing from EDF Renewables, Enbridge, and CPP Investments, among others, since 2016.
$4.1M question: How does a wind farm impact its surrounding marine environment?
Pilot programs were anticipated to provide engineering information. But the Provence Grand Large took it to another level by allocating $4.1 million to a 20-year-long environmental study and monitoring project, an extremely ambitious undertaking for such a small facility.
The project studies the marine megafauna, seabirds, and seafloor communities within specific before-and-after windows. Since 2022, an independent scientific committee, which has been set up by the French state, is overseeing this process, which ensures quality and transparency of the gathered data. This data will not stay where it came from; rather, it will be used to develop designs for upcoming French floating wind farms, such as the Méditerranée Grand Large, which has been contracted out to EDF Renewables in December 2024.
Dolphins on every trip: What boat surveys are revealing
A result which has emerged from the boat observation missions is that of dolphins. Thirty-five to forty, consistently, each time, in the vicinity of the farm. A statistic which seems more likely to give rise to speculation than to provide any concrete answers, such as whether the dolphins are attracted to, oblivious to, or just living in the area.
Seasonal patterns emerge too. Shearwaters appear in significant numbers through summer. As water temperatures fall in winter, species diversity drops noticeably. Below the surface, hydrophones deployed at 50 meters depth record cetacean acoustic signals continuously — before installation, during construction, and through the operational phase. When a dolphin echolocates near a turbine platform, that sound is captured and stored, building a behavioral record that will only grow more valuable with time.
Scooping mud to read the seafloor’s story
Dolphins are tangible and measurable, but there’s another more subtle layer of information coming from the seabed. Biosediment surveys involve taking mud core samples from the seabed and examining the animal life living in the mud—worms, crabs, snails, and other benthic creatures that people rarely see.
The same standard mud core samples were taken both before and after the turbines were put into place, thus generating a clear picture of biological change. The benthic community is an excellent indicator of ecological change because it cannot leave its habitat like fish can. It stays in one place. If sediment composition changes, or the anchor cables create a hard substrate that brings new species to colonize, the mud core samples will reflect this.
Watching the skies: Radar, cameras, and nesting gulls
At above-water level, there is an equally systematic approach. A radar placed at the center turbine provides information about the path of birds and the interaction of avifauna with structures. All three turbines have cameras running 24/7 and are connected with acoustic deterrent systems which activate when the birds come close to the turbines.
The farm also works with the Camargue Regional Nature Park to create and renovate nesting sites for Mediterranean gulls and terns, protecting those species from predators and improving their reproductive success. The turbines, in this sense, function as more than power generators — they’re active wildlife monitoring stations, embedded in an ecosystem they are simultaneously studying.
A template for the turbines yet to come
Every dataset collected at Provence Grand Large will inform what comes next. The 20-year monitoring window means the farm will keep generating ecological data long after it becomes routine infrastructure, capturing slow-developing changes that shorter studies would miss entirely. As floating wind expands into deeper waters globally, the Gulf of Fos is quietly becoming one of the world’s most closely observed marine test sites.
Visualize the research ship returning to port at the end of the day, its hard drives packed and its journals shut. Above it, the three turbines spin slowly amidst the clouds. Below it, fins are slicing through the water, belonging to the dolphins, still present, calm, and gliding through the sea that observes just as it is observed.
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.
