Small eaters, big impact: suspension feeders reshape the food web in offshore wind farms
Offshore wind farms attract a diverse marine life. New research shows that the fauna that colonizes the wind turbines also influences the marine food web. In particular, the increase in suspension feeders – such as mussels, amphipods and anemones that extract small food particles from the water – helps to transfer carbon more quickly and directly into the food web.
The offshore wind sector will continue to expand to help meet the EU’s targets for reducing CO₂ emissions. While much is already known about the impact of offshore wind farms on local biodiversity, the key question remains what these changes mean for the functioning of marine ecosystems as a whole.
“We collected a lot of samples in the Belgian part of the North Sea and beyond to model the food webs of natural and artificial habitats,” said Emil De Borger (Ghent University & NIOZ), principal investigator of the study. “This allowed us to investigate in detail how these systems function, and to compare the ecological processes of soft sediment habitats with those around wind turbines.”
Jan Vanaverbeke (UGent & Institute of Natural Sciences), co-author of the new study, emphasizes another important point: "Until now, most studies on food webs in offshore wind farms were based on simulated environments. In other words: wind farms that only exist in scientific models. We took a different approach. Our goal was to develop models of food webs based on reality, using data collected in real, operational wind farms."
Using stable isotope analysis and ecological food web modelling, the researchers reconstructed and quantified how carbon and energy flow between species through food uptake, from plankton to fish. The resulting models revealed striking differences between natural sandy bottoms and offshore wind farms.
Biodiversity hotspots
The study confirms that artificial reef structures such as offshore wind farms are indeed species-rich compared to surrounding soft-bottom habitats. However, many of these species occur only in a very low biomass when extrapolating to the scale of the offshore wind farm, which includes a lot of “empty space” in between the turbines.
The real ecological game-changer is the proliferation of suspension feeders, organisms such as mussels, amphipods, and anemones that attach to the hard surfaces of turbines and feed by extracting organic particles directly from the water column. The turbines thus promote a more direct uptake of the carbon and energy stored in the food particles into the food web. On sandy seabeds, carbon and energy often have to make longer detours.
“These suspension feeders act like biological pumps,” explained De Borger. “They take in carbon-rich particles from the water, process them, and enrich the surrounding sediment with organic matter. That deposition, in turn, becomes food for bottom-dwelling species, creating new feeding opportunities in an otherwise energy-poor environment. It is these numerous interactions between a diverse community of species that lead to the high productivity of the new food web.”
Fish diets and carbon budgets
One of the study’s notable findings relates to the diets of fish in and around wind farms. Field observations confirm earlier research suggesting that some fish species shift their diets toward prey that are particularly abundant near turbines.
“This supports the idea that offshore wind farms aren’t just physical structures,” said co-author Ulrike Braeckman (Ghent University & Institute of Natural Sciences). “They actively shape species behaviour, including predator-prey relationships. Some fish are clearly taking advantage of the concentrated food sources created by the turbines. It’s an engineered ecosystem that’s influencing natural processes.”
Understanding these food web changes is critical not just for scientific knowledge, but for practical management. “Food webs tell us about ecosystem stability, biodiversity, and even our food supplies and carbon budgets,” added Jan Vanaverbeke. “As we continue to increase offshore wind capacity, we need to understand how these systems function, both to protect marine life and to sustainably manage ocean resources.”
Balancing renewable energy and ecosystem stewardship
The study underscores the importance of integrating ecological insights into the planning, construction, and monitoring of offshore renewable energy projects. As Europe races to expand its offshore wind capacity to meet climate goals, these findings provide valuable guidance on how to balance the impact on the marine environment with the sustainable goal of offshore wind energy production.
The researchers call for a wider use of models based on real ecosystems and indicate that long-term monitoring is necessary to track and understand changes in food web dynamics and biodiversity over time. "Our work shows that wind farms can enhance certain ecological pathways, but it is essential to understand which ones, and how they affect the broader system," says Emil De Borger.
The study “Offshore wind farms modify coastal food web dynamics by enhancing suspension feeder pathways” is freely available and was published in Communications Earth & Environment by a multidisciplinary team of marine researchers from Ghent University (Marine Biology Research group) and marine institutes from Belgium and the Netherlands (Institute of Natural Sciences; Flanders Research Institute for Agriculture, Fisheries and Food – ILVO; Royal Netherlands Institute of Sea Research – NIOZ; Wageningen Marine Research).