A multiscale framework for bioinspired additively manufactured artificial reefs in coral restoration

The ongoing degradation of coral reefs has led to increased research into artificial reefs, particularly the use of additively manufactured structures for habitat restoration. Although advances in geometric complexity and material development have been achieved, these factors alone are insufficient for ecological restoration. To address persistent gaps in integrating design, material selection, and ecological outcomes, this review introduces a multiscale framework for evaluating bioinspired, additively manufactured artificial reefs. The framework comprises six interrelated dimensions: restoration and site requirements, bioinspired and parametric design, material and environmental compatibility, manufacturing and constructability, multiphysics performance assessment, and validation, monitoring, and implementation. Evidence is systematically evaluated across four hierarchical scales: material and surface, module and geometry, reef and site, and implementation and system. The analysis shows that overall performance depends on the interaction of material formulation, geometric configuration, manufacturing process, site-specific conditions, and decision-making across scales. Translating bioinspired features into metrics requires data on chemical stability, degradation behavior, biological response, and durability. Manufacturing must preserve intended surfaces, cavities, porosity, and structural attributes. Although hydrodynamic and structural models can guide design, their predictive value depends on model assumptions, material characterization, experimental validation, and field conditions. Current evidence remains disconnected across ecological objectives, material and manufacturing qualification, physical performance assessment, and long-term monitoring. The proposed framework aims to address these discontinuities by linking restoration objectives to design, qualification, multiphysics assessment, validation, and adaptive implementation. This approach offers a structured basis for evaluating trade-offs, assessing evidence strength, and guiding the development of artificial reef infrastructure for coral restoration.