Artificial shorelines lack natural structural complexity across scales (dataset)

From microbes to humans, habitat structural complexity plays a direct role in the provision of physical living space and increased complexity supports higher biodiversity and ecosystem functioning across biomes. Natural coastlines are structurally complex transition zones between land and sea that support diverse ecological communities but are under increasing pressure from human activity. Coastal development and the construction of artificial shorelines are changing our landscape and altering biodiversity patterns as humans seek both socio-economic benefits and protection from coastal storms, flooding, and erosion. In this study, we evaluate how much structural complexity is missing, and at which scales, with the creation of artificial structures compared to naturally occurring rocky shores. We quantified the structural complexity of both artificial and natural shores at resolutions from 1 mm through to 10s of m using three remote sensing platforms (handheld camera, terrestrial laser scanner and uncrewed aerial vehicles) across both artificial and natural shorelines. Natural shorelines were approximately 20-50 % more structurally complex and offered greater structural variation between locations. In contrast, artificial shorelines were more structurally homogenous and typically deficient in structural complexity across scales. Our findings reinforce concerns that replacing natural rocky shorelines with artificial structures simplifies coastlines at organism-relevant scales. Furthermore, we offer much-needed insight into how structures might be modified to more closely capture the complexity of natural shorelines that support biodiversity.