Reef Arks Frequently Asked Questions


What is the shape and size of an Arks?
Coral Reef Arks are geodesic, negatively buoyant structures approximately 10-feet in diameter. The geodesic provides a strong framework for mounting the ARMS and provides a large internal volume that recreates the essential subsurface space of a healthy coral reef. These interstitial spaces provide habitat for essential invertebrates like crabs, urchins, lobsters, sponges, et cetera and are important for nutrient cycling.

The geodesic shape is very strong and simple to construct. It is also extremely adaptable; simply changing the number of "faces" on the geodesic allows a different sized Ark to be built. This means that small and very large Arks will be constructed from the same basic materials.

The geodesic shape also creates a naturally regulating system, where pieces of corals break off when they grow too far out from the structure. This will self-regulate the Arks weight over long-time frames and prevent them from exceeding the buoyancy capacity of the surface buoy.

We are currently testing methods to electrify the geodesic frame in order to precipitate calcium carbonate on the Arks to build the structure with very minimal starting materials.

How are the Arks tethered?
A mooring line runs between the seafloor and a surface buoy. The surface buoy provides the buoyancy to suspend the Arks and houses the solar cells for power, communications, and navigation beacons. A secondary "drop line" is suspended from the surface buoy and runs through a central cylinder in the Arks. We will be testing an attachment system that will allow vertical adjustment of the Arks within the water column, allowing the Arks to be moved in the case of extreme weather events (e.g., hurricanes, cyclones, warm-water events).

Where will the Arks be deployed?
The prototype Arks will be deployed off the coast Curacao, which has necessary infrastructure to support the development phase. Curacao is also the site of the sea urchin restoration experiments and coral larva recruitment projects. The long-term goal is to place the Arks away from pollution runoff and in areas where climate change impacts are predicted to be less severe. Multiple Arks will be sited together in order to maximize connectivity and productivity, as well as gain logistical benefits (e.g., permitting, monitoring, and navigational alerts).

Will the Arks be able to survive 100 years?
Yes, the goal is to build Arks with a life expectancy of 100-plus years with very little to no maintenance. This time frame was chosen because: 1) the engineering specifications are obtainable, and 2) this will be a period of major climate change under any reasonable climate modeling scenario.

Arks are designed so that pieces of reef will naturally break off and fall to the seafloor, maintaining the weight of the Arks over time. Calcifying organisms, including coral and crustose coralline algae (CCAs), will cement the components of each Ark together. Because the Arks are living structures they will heal fractures and cracks over time.

Why will Arks be suspended rather than on the seafloor?
The goal is to get corals into the clean, open ocean water at the right light level.

What if a Coral Reef Ark breaks free?
The Arks are negatively buoyant and if one were to break loose (highly unlikely), then it will sink and not become a floating hazard.

How will you mitigate navigational hazards created by Coral Reef Arks?
Arks will be sited outside major navigational lanes and will be marked by surface buoys with appropriate navigation markers. The required permits (e.g., Army Corps of Engineers and the Coast Guard in US waters) will be obtained and a Notice to Mariners will be sent out before installing the Arks.


How will Arks benefit fisheries?
One of the advantages of creating a reef-like ecosystem with the Arks is the associated fisheries. The large internal spaces of the geodesic sphere will create habitat for invertebrates, which in turn will be eaten by groupers and other fishes. As with a natural reef, the large surfaces will support algae, which in turn will support grazing fish and their predators (including reef sharks). The Arks are designed to maximize seawater flow which greatly enhances reef health. Artificial structures with larger vertical dimensions have 10-100 times higher fish production relative to structures lying on the seafloor (US Department of the Interior 2003) and Arks are analogous to anchored fish aggregating devices (FADs). FADs attract pelagic fish species, allowing them to be caught and saving fishers from traveling long distances, which is energy intensive and dangerous. Ultimately, the goal is to use the Arks to create new fisheries and reduce fishing effort.

What about the other animals?
Our preliminary studies showed that most coral reef taxa recruit to the ARMS. Additionally, certain ecologically important species may also be specifically collected and attached to the Arks. For example, in one pilot project we will be collecting corals from structures that the military is planning to remove. By harvesting the corals and moving them to Arks, we will develop valuable biomaterial for conservation and restoration, and this will also help the Navy mitigate the damage (a legal requirement).

Will the animals on the Arks suffer genetic bottlenecks?
The goal is place 10-20 Arks near each other (determined by the mooring depth). This proximity will allow for genetic exchange of swimming and spawning organisms between the Arks. We will also test the effect of moving individual ARMS between Arks to facilitate exchange of sessile, non-spawning organisms.

How old do corals need to be to survive in the open ocean?
Corals can survive in the open ocean from the larval stage onward. However, they need an appropriate settlement structure like the Arks and ARMS. On degraded reefs, young corals are smothered in microbial-laden water and sediments. The high-water velocity environment on Arks will eliminate sedimentation of coral settlers, and reduce algal-mediated microbialization and the associated hypoxia that kills corals.

Why won't Arks become degraded and colonized by non-coral organisms (e.g., algae, invasive species, biofouling organisms)?
Proper location of the Arks will provide many advantages to the corals (e.g., oxygenated, low nutrient water) and disadvantages their competitors (which are favored by high nutrient conditions).

How well do ARMS attract coral larvae?
Corals naturally recruit to the ARMS (we have observed over 100 coral species so far). In addition to natural recruitment, we may also transplant adults (e.g., when the corals are being removed for other reasons). To enhance recruitment, we and several other groups are continually improving the settlement surfaces for corals. We will take advantage of any findings from these studies to enhance our current ARMS design. In addition, many groups, including our direct collaborators, are generating millions of sexually produced coral offspring. ARMS will be used as settlement surfaces for these larvae and then moved to Arks to boost the number of genetically distinct coral individuals on Arks to exceed those of natural populations.

Could fishing gear get entangled on the Arks?
Yes, Arks or any other marine structure will be susceptible to entanglement by fishing gear. The surface buoy will provide warnings to fisherman.


How will the ARMS get to the Arks?
Initially everything will be done by divers. However, it is easy to imagine a future where robotic systems would move the ARMS and help with maintenance. By making the building blocks of the Arks relatively small and diver-deployable, local groups will be able to develop their own projects. And the geodesic design means that large, open ocean-going projects can build very large Arks with the same components.

How do you know that the ARMS biodiversity will survive in its new location?
Coral reefs form on nearly any substrate in the tropical seas, including rocks, old coral, sunken ships, and oil rigs. These sites are often in the open ocean and these communities thrive. Coral reefs also form on some of the most remote islands on the planet and tend to be some of the healthiest reefs remaining on Earth. This phenomenon highlights that coral reefs can form nearly anywhere conditions are appropriate (temperature, light, etc.).

Will the new Arks locations still be vulnerable to climate change stressors (e.g., acidification, sea surface temperature)?
Our team is using climate models to identify locations that are projected into the future to be most suitable for coral Arks. The open ocean is much more predictable in respects to temperature changes and pH than are near-shore sites, which is another reason to place the Arks far from land. Additionally, the mobility of Arks will allow them to be moved if conditions unexpectedly deteriorate.


How will the Arks promote tourism?
Arks will be beautiful coral reefs floating in blue water. They will attract large fish and SCUBA divers alike. Hotels and resorts will be able to place Arks near their beaches, giving their guests a destination and providing valuable coral habitat.

Will Arks help with coastal protection?
Arks themselves will not be big enough to provide coastal protection. However, enhanced restoration of coral reefs, using Arks, will help build up the essential barrier reefs.

Why are small molecules important with respect to bioprospecting?
Small molecules are critical players in biological processes and can be particularly useful in the development of new drugs to fight diseases like cancer. They are also important sources of antibiotics and other natural products.

Will Arks sequester carbon dioxide?
Arks will sequester carbon via building calcium carbonate structures and by dropping fragments into the deep sea. The building of calcium carbonate will be bolstered by electrifying the geodesic frame in order to precipitate calcium carbonate from seawater as part of the construction process. We estimate that we will remove one ton of carbon per Arks. So Arks will be net neutral or even negative in regards to CO2 production.


How much will the Ark prototype cost?
We are raising $1 million USD to build and test the first Ark prototype in the field. This includes testing different smaller prototypes in flow chambers, constructing and deploying a full-sized prototype, and monitoring succession for 5 years.

Where will the first Ark be built?
The necessary personnel, facilities, and collaborations are in San Diego and Curaçao. Different aspects of the project are being built and tested in both sites and Curaçao will be the first site for the full-sized prototype.

Aren't coral reefs doomed and won't the Arks be a waste of time?
No, in many parts of the world coral reefs are surviving and even thriving. In other places, degraded reefs are recovering. There is hope and the Arks will give us a tool to increase the rates of restoration, while insuring against periodic disasters like wide-spread bleaching.

How are Arks better than artificial reefs or other conservation/restoration programs?
Arks transport both species and the essential ecosystem functions. Without these functions (structure and nutrient recycling), transplanted corals will not survive. The ability to move, exist in the open-ocean, and recapitulate natural reef functions make the Arks an essential tool for both conservation and restoration.

What is the plan for monitoring and maintaining Arks?
Initially, Arks will be monitored to assess survival, growth, and biodiversity as they grow into an established reef structure. To assess the efficacy of Arks as a mitigation and conservation tool, each deployed Ark will be monitored quarterly in Year 1 and every other quarter in Year 2. A full ecosystem workup of water chemistry and biodiversity will be completed by the Rohwer lab (

For the long term, we are building a business plan that will include non-profit and for-profit uses of the Arks. The goal is to develop financial models that will ensure the coral reefs thrive in the future.

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