Artificial reefs (ARs), a form of anthropogenic intervention in marine habitats, have a long history of deployment and continue to proliferate worldwide. Based on a comprehensive literature review and meta-analysis, we show that (i) ARs have evolved from socioeconomic-oriented tools into often-used components of active marine restoration, yet this transition conflicts with the continued use of eco-unfriendly materials, hindering upscaling; (ii) ARs positively impact marine organisms at community, population, and individual levels, but their contributions to organismal fitness remain limited compared to natural reefs. To address these limitations, we advocate a paradigm shift toward “rewilding ARs”─temporary structures designed to create opportunities for natural reef formation, enhance habitat quality, and gradually degrade to minimize human impact. These features support the transition from active intervention to spontaneous recovery, promoting sustainable biodiversity recovery by improving organism fitness and facilitating upscaling. Integrating insights from ecologists, engineers, legal experts, environmental consultants, and NGOs, we introduce six guiding principles for “rewilding ARs” to ensure effective, durable, no-regret, scalable, permit-friendly, and outcome-optimized implementation. Lastly, we present pioneering examples of innovative ARs progressing toward these principles, serving as references for future endeavors. ... Read more

In the past, a large part of the seabed of the southern North Sea was covered by hard substrates, including oyster beds, coarse peat banks, and glacial erratics. Human activities, particularly bottom trawl fisheries, led to the disappearance of most of these hard substrates, resulting in the loss of its associated diverse benthic life as well. However, the introduction of human-made structures such as offshore wind farms in the North Sea, offers a chance to provide habitat of similar functionality as the former hard substrates. The offshore wind farm infrastructure generally contains layers of rock material deployed at the base of the wind turbine foundations and cable crossings, so-called scour protection, aiming to prevent seabed erosion. The scour protection offers a unique habitat for rock-dwelling benthic organisms in an otherwise mostly soft-bottom environment. By designing the scour protection to be more nature-inclusive, the biodiversity of benthic life can be increased. In this study we examined the effect of substrate material and grading of the scour protection on the epibenthic biodiversity in situ. This was done by deploying research cages containing crates (n = 15) with different types of substrates (concrete, granite, and marble) on the scour protection within an offshore wind farm in the Dutch North Sea. The study revealed a significant (p < 0.05) positive relation between available substrate surface (pebble size) and taxonomic richness. Furthermore, a biological trait assessment of living habits (Tube dwelling, Burrowing, Free living, Crevice dwelling, Epi/endobiotic, and Attached) revealed variations in habit modes across substrate types, with marble and concrete samples showing greatest divergence. Marble samples contained a higher prevalence of tube dwelling organisms, whereas concrete samples contained a relatively higher prevalence of free living, epi/endobiotic and crevice dwelling organisms. The findings support the value of nature-inclusive scour protection designs, emphasizing that both taxonomic and functional diversity can be enhanced by increasing the available surface area of the scour protection and incorporating a variety of substrate types. By adopting these nature-inclusive design components, the coexistence of renewable energy production and a diverse marine benthic community can be further optimized. ... Read more