Emerging 3D technologies for future reformation of coral reefs: Enhancing biodiversity using biomimetic structures based on designs by nature

Using waste biomass to produce 3D-printed artificial biodegradable structures for coastal ecosystem restoration

The loss of ecosystem functions and services caused by rapidly declining coastal marine ecosystems, including corals and bivalve reefs and wetlands, around the world has sparked significant interest in interdisciplinary methods to restore these ecologically and socially important ecosystems. In recent years, 3D-printed artificial biodegradable structures that mimic natural life stages or habitat have emerged as a promising method for coastal marine restoration. The effectiveness of this method relies on the availability of low-cost biodegradable printing polymers and the development of 3D-printed biomimetic structures that efficiently support the growth of plant and sessile animal species without harming the surrounding ecosystem. In this context, we present the potential and pathway for utilizing low-cost biodegradable biopolymers from waste biomass as printing materials to fabricate 3D-printed biodegradable artificial structures for restoring coastal marine ecosystems. Various waste biomass sources can be used to produce inexpensive biopolymers, particularly those with the higher mechanical rigidity required for 3D-printed artificial structures intended to restore marine ecosystems. Advancements in 3D printing methods, as well as biopolymer modifications and blending to address challenges like biopolymer solubility, rheology, chemical composition, crystallinity, plasticity, and heat stability, have enabled the fabrication of robust structures. The ability of 3D-printed structures to support species colonization and protection was found to be greatly influenced by their biopolymer type, surface topography, structure design, and complexity. Considering limited studies on biodegradability and the effect of biodegradation products on marine ecosystems, we highlight the need for investigating the biodegradability of biopolymers in marine conditions as well as the ecotoxicity of the degraded products. Finally, we present the challenges, considerations, and future perspectives for designing tunable biomimetic 3D-printed artificial biodegradable structures from waste biomass biopolymers for large-scale coastal marine restoration.

Restoration ecology meets design-engineering: Mimicking emergent traits to restore feedback-driven ecosystems

Ecosystems shaped by habitat-modifying organisms such as reefs, vegetated coastal systems and peatlands, provide valuable ecosystem services, such as carbon storage and coastal protection. However, they are declining worldwide. Ecosystem restoration is a key tool for mitigating these losses but has proven failure-prone, because ecosystem stability often hinges on self-facilitation generated by emergent traits from habitat modifiers. Emergent traits are not expressed by the single individual, but emerge at the level of an aggregation: a minimum patch-size or density-threshold must be exceeded to generate self-facilitation. Self-facilitation has been successfully harnessed for restoration by clumping transplanted organisms, but requires large amounts of often-limiting and costly donor material. Recent advancements highlight that kickstarting self-facilitation by mimicking emergent traits can similarly increase restoration success. Here, we provide a framework for combining expertise from ecologists, engineers and industrial product designers to transition from trial-and-error to emergent trait design-based, cost-efficient approaches to support large-scale restoration.

Evaluating biodiversity for coral reef reformation and monitoring on complex 3D structures using environmental DNA (eDNA) metabarcoding

Quantifying coral reef biodiversity is challenging for cryptofauna and organisms in early life stages. We demonstrate the utility of eDNA metabarcoding as a tool for comprehensively evaluating invertebrate communities on complex 3D structures for reef reformation, and the role these structures play in provisioning habitat for organisms. 3D design and printing were used to create 18 complex tiles, which were used to form artificial reef structures. eDNA was collected from scraping tile surfaces for organismal biomass and from seawater samples around the artificial reefs in the Gulf of Eilat/Aqaba, Red Sea. Metabarcoding targeted the mitochondrial COI gene with specific primers for marine biodiversity. We provide the first eDNA biodiversity baseline for the Gulf of Eilat/Aqaba, capturing extensive information on species abundance, richness, and diversity. Tile tops had higher phylogenetic diversity and richness, despite a higher abundance of organisms on tile bottoms, highlighting the detection of cryptic organisms with eDNA. We recommend eDNA metabarcoding for reef restoration initiatives, especially for complex marine structures, to improve success and evaluation of biodiversity.