In addition to building reefs, which occur offshore of numerous Department of Defense (DoD) installations within DoD submerged lands, tropical corals grow on military structures (e.g., boat ramps, piers) and expended materials. Military activities such as testing, training, and in-water construction work sometimes incidentally or intentionally damage natural or structure-attached corals or coral reefs. The Sikes Act requires the United States (US) Military to cause no net harm to protected habitats and species, which includes coral reefs and several species of Endangered Species Act listed corals. Due to their protected status, many corals and coral reefs impacted by DoD activities legally require mitigation. The primary mitigation approach, typically associated with in-water construction work, is to translocate individual adult corals to new locations, which can be exceedingly expensive, typically has low success rates, and does not completely account for ecosystem losses; thus, further compensatory mitigation in addition to translocation is usually required. This project focuses on translocating a larger proportion of reef diversity, and providing new habitat with improved physical conditions to encourage growth of mini-reefs in advantageous locations that would then produce larvae and help recolonize impacted areas. With the approach presented in this project, the project team expects to provide an improved alternative method for coral reef mitigation to the DoD, a growing need as regulatory pressure to mitigate for corals increases.

This project will demonstrate a new technology for coral mitigation that is expected to improve upon existing technologies by resulting in higher translocation success rates, additional ecosystem benefits, and lower overall costs associated with coral mitigation. “Coral Arks,” developed by the Rohwer Laboratory at San Diego State University, are new technologies that represent two major improvements for coral mitigation: (1) portable and depth-adjustable structures that provide more flexible relocation and improved physical conditions for translocated corals and (2) a new method to translocate not only adult corals, but also a significant fraction of the diverse biota that comprise coral reefs, and are essential to their survival and ecosystem services.

The project team anticipates that “Coral Arks” will result in (1) improved survival rates for translocated adult corals, (2) improved associated metrics of coral reef function, such as associated fish biomass, coral growth rates, and nearby coral recruitment, and (3) enhanced community biodiversity, compared to the traditional approach of translocating corals to existing hard substrate or emplaced materials such as Reef Balls or boulders. Further, “Coral Arks” represent a new, mobile artificial reef device, that will allow both protection of the artificial reef system via vertical adjustment ahead of storms, for example, and minimizes the potential for future conflict with DoD requirements by introducing flexibility in siting. Because of these benefits, “Coral Arks” are anticipated to result in cost savings to mitigate for an equivalent amount of unavoidable reef impact, compared to traditional translocation and compensatory mitigation requirements.