The influence of offshore windpower on demersal fish

TLDR

Offshore windpower is rapidly expanding in northwestern Europe, yet its effects on marine ecosystems remain poorly understood. This study examines whether wind turbines act as artificial reefs and fish aggregation devices, potentially increasing local fish densities or altering assemblages. Researchers used visual transects at two Swedish Baltic Sea wind farms to assess fish communities and habitat composition around turbines. Fish abundance was higher near turbines, with distinct community structure on monopiles and greater mussel and barnacle coverage, indicating that wind farms serve as combined artificial reefs and fish aggregation devices for small demersal fish.

Abstract

Abstract A significant expansion of offshore windpower is expected in northwestern Europe in the near future. Little is known about the impacts it may have on the marine environment. Here, we investigate the potential for wind turbines to function as artificial reefs and fish aggregation devices (FADs), i.e. whether they would locally increase fish densities or alter fish assemblages. Fish communities and habitat composition were investigated using visual transects at two windpower farms off the southeastern coast of Sweden, central Baltic Sea. Fish abundance was greater in the vicinity of the turbines than in surrounding areas, while species richness and Shannon–Wiener diversity (H′) were similar. On the monopiles of the turbines, fish community structure was different, and total fish abundance was greater, while species richness and diversity (H′) were lower than on the surrounding seabed. Blue mussels and barnacles covered most of the submerged parts of the turbines. On the seabed, more blue mussels and a lesser cover of red algae were recorded around the power plants than elsewhere. Results from this study suggest that offshore windfarms may function as combined artificial reefs and fish aggregation devices for small demersal fish.