X-REEFS Project: Overview

The goal of the X-REEFS project is to develop an innovative hybrid biological and engineered reef-mimicking structure, with resilient ecological properties designed to survive changing environmental conditions. We are developing biocompatible, wave-attenuating structures that promote rapid growth of corals and build reef resilience by increasing coral resistance to thermal stress and disease to withstand future changes. 

By bringing together specialists in structural engineering, physical and chemical oceanography, reef ecology and restoration, and adaptive biology, the X-REEFS project is creating a hybrid reef-like structure that will significantly reduce risk to communities and DoD installations in coastal areas, reduce maintenance costs, promote ecosystem health, and strengthen DoD’s ability to maintain its infrastructure and military readiness.

Our base structure will use a novel, modular, interlinked system based on perforated hexagonal prisms, called SEAHIVEs. The geometry and porosity of each element will be optimized for wave energy dissipation and stability. The system will be enhanced using complex lattice forms and advanced coral mimics that increase wave dissipation, reduce the material used, and create structural complexity. To reduce the project’s carbon footprint, our team will use concrete with large amounts (approximately 40%) of supplementary cementitious materials to recycle industrial by-products while reducing CO₂ emissions.

We will use the University of Miami’s (UM’s) world-class SUrge STructure Atmosphere INteraction (SUSTAIN) facility, the only storm simulator facility in the world capable of generating Category 5 hurricane-force wind and waves, as well as an in situ full-scale test bed site off Miami Beach, for testing innovations and designs. To achieve the wave reduction targets put forward by the DoD, we will use a multi-model strategy to assess and design for the interaction between waves, storm surge, structure design and placement using laboratory and field benchmarks. To assess performance, we will downscale multi-decadal historical wave-forcing site conditions and climate change projections, including sea level rise to characterize wave attenuation and flood reduction.

Read more about our work to develop biocompatible, wave-attenuating structures here.

To address current limitations in larval settlement and growth in reef restoration, the X-REEFS team will innovate by experimenting with enhanced physical and chemical habitats to increase the recruitment and growth of corals and the reef community. To enhance durability and support reef resilience, we will explore the use of specialized concretes and coatings as sources from which calcification enhancers can be slow-released to boost coral and crustose-coralline algae calcification.

For our prototypes, we will work with a variety of scales, including texture at the millimeter scale, to increase rugosity, modify pH, and promote the recruitment and growth of corals and the reef community. Contact-based anti-algal coatings and invertebrate grazers (i.e., urchins, snails) will be deployed onto the structure to minimize macroalgal growth.

The X-REEFS project will target resilient and fast-growing coral species and genotypes for propagation and outplanting to the structure. Novel chemical and bacterial cues will promote coral settlement in either controlled propagation or via direct seeding of coral larvae to the structures.

Read more about our work to increase accretion of corals and their allies here.

We will test deploy additional interventions to increase the resilience and adaptive capacity of coral recruits. Traits that support coral and reef resilience (such as heat tolerance and fast growth) will be selected using new sperm cryopreservation techniques and ex situ coral spawning. Our team will selectively breed coral stocks, including parents sourced from outside of Florida, to help increase thermotolerance, as well as manipulate the microbial partners of corals to increase their resilience.

We will further innovate by targeting the production of "chimeric" (multi-genotype) colonies and staghorn-elkhorn coral hybrids for our breeding efforts, allowing us to leverage the potential high resilience and rapid growth of these corals. 

Finally, we will integrate a new tool for rapid, standardized stress testing of corals (CBASS) across these activities to rapidly identify parents for both direct outplanting and breeding efforts, and to measure changes in thermotolerance as a result of our interventions. 

Read more about our work to enhance coral adaptive capacity here.

The X-REEFS project focuses on Florida and the Caribbean to develop, test, and implement hybrid coral reefs designed to maximize wave attenuation at minimal cost, while also being self-repairing, fast-growing, and resilient to future sea-level and climate projections. The first test site represents a natural extension of the many years of experience that our Florida-based team brings to the project and our upcoming test bed project in Miami Beach, which already combines hybrid reef structures with interventions to increase coral resilience. The methodologies, techniques, and structural solutions developed as part of the X-REEFS project will inform reef restoration projects globally.