Abstract
The expansion of marine artificial structures (MAS), particularly offshore wind farms (OWFs), has raised questions about their ecological role and potential to enhance diversity. While MAS can function as artificial reefs, evidence remains fragmented, and the effectiveness of nature-inclusive design (NID) in MAS is poorly understood. This study synthesises global evidence on diversity responses to MAS, with a focus on OWFs and NID. Literature searches following PRISMA guidelines identified 104 relevant studies, of which 55 provided 367 effect sizes for a meta-analysis following outlier removal.
MAS significantly increased diversity relative to controls (SMD = 0.899 ± 0.122 SE, P < 0.001), though responses were highly context dependent. The strongest gains were observed for oil and gas platforms, artificial reefs, and coastal infrastructure, while OWFs showed weaker, non-significant effects, although responses were context dependent. Diversity responses increased with structure age and were more pronounced for sessile than mobile taxa in OWFs. NID interventions enhanced diversity in coastal infrastructure, artificial reefs, and add-on units. However, studies assessing NID in OWFs were limited, and as direct evidence remains scarce, conclusions on their effectiveness in this context are largely inferential. A halo effect was detected, with increases in diversity extending ∼50 m into surrounding soft sediments.
These findings highlight that while MAS can enhance diversity, outcomes are highly variable and context dependent. For OWFs, realising ecological benefits will require broader application of NID, long-term monitoring, designs tailored to site-specific ecological objectives, and stronger evidence to guide policy and industry adoption.