Experimental study of a 3D printing application to produce substrates for coral propagation

Abstract

Additive Manufacturing provided an innovative method of production for ecology restoration areas, allowing rapid prototyping of substrates with high complexity morphologies, a critical and fundamental attribute to guarantee coral growth and Crustose Coralline Algae. The experimental study has a purpose to prove and qualify the influence of textured surface substrates morphology and chemical composition on the growth and propagation of transplanted corals. It was used Additive Manufacturing and silicone molds for converting three-dimensional samples into limestone mortar with white Portland cement substrates for coral growth. A systematic methodology was established starting with a deep bibliographic research on scientific articles, related books in design, biology and engineering areas and several national and international case studies about implementation of artificial marine structures. Based on literature review, tiles samples were designed and printed with different geometries and textures inspired by soil erosion and nature marine environment. Commercial coral frag tiles were analysed through Scanning Electron Microscopy (SEM) to identify the main chemical elements. Tropical coral species with fast growth rate in captivity were selected namely Montipora Danae; Montipora Confusa and Montipora Undata. The developed substrates were introduced into a closed-circuit aquarium to monitor the coral weekly evolution process and analyse the results obtained. The experimental results provided positive statistical parameters for future implementation tests, concluding that the intensity of textured surface, interfered favourably in the coralline algae biofilm growth. Also, the chemical composition and design of the substrates were determinant factors for successful coral propagation. Recesses and cavities mimic the natural rocks aspect and promote, at the same time, the presence and interaction of other species that favour the richness of the ecosystem.