Leveraging built marine structures to benefit and minimize impacts on natural habitats

Many natural marine habitats are decreasing in extent despite global conservation and restoration efforts. In contrast, built marine structures, such as hardened shorelines, offshore energy and aquaculture infrastructure, and artificial reefs, are increasing in extent-and, in some locations, represent over 80% of nearshore, structured habitat. When introduced into the seascape, built marine structures inevitably interact with natural habitats, but these structures are not typically designed to support natural systems. This approach often results in overall harm to natural systems, further impeding marine conservation goals. However, there is growing recognition within the ocean management and engineering community that built marine structures can be strategically designed to minimize their negative impacts and potentially support ecosystems and associated biota. We synthesize the best available science and provide bright spot examples of how leveraging built marine structures to mimic or facilitate natural habitats can help recover biodiversity, augment ecosystem services, and rehabilitate degraded habitats, providing positive outcomes for people and nature in a changing climate. Despite these bright spots, we caution that built structures typically have overall negative environmental consequences for natural habitats and should not be used in lieu of conventional habitat restoration or conservation or to justify the destruction of natural habitats.