US military wants to build fake reefs to protect bases from storms

The US military is funding research to develop “Reefense” structures that rapidly recruit oysters and coral for defence against storm surges

By Jeremy Hsu

The US military wants to build artificial reefs to protect coastal bases from storm surges amid rising seas and climate change. Its “Reefense” programme has awarded three contracts with the goal of using both artificial and natural defences to bolster the protection provided by human-built sea walls and concrete breakwaters alone.

The project comes after catastrophic incidents such as Hurricane Michael, a Category 5 storm that wrecked every single building at Florida’s Tyndall Air Force Base and hit some of the Air Force’s expensive F-22 Raptor fighter jets in 2018, resulting in $4.7 billion in damage overall.

“We’re here to develop self-healing, hybrid biological and engineered reef-mimicking structures that mitigate coastal flooding and erosion, but that also have a living component to them,” says Catherine Campbell at the US Defense Advanced Research Projects Agency (DARPA).

A first line of defence envisioned by DARPA’s Reefense programme would consist of an artificial structure capable of dissipating some of the power of incoming waves and storm surges. That would pave the way for oysters or corals to grow on the artificial foundation and further strengthen the coastal protection capabilities.

While natural reefs usually start shaping up over five to 10 years, DARPA is aiming for these artificial reef structures to spur serious oyster and coral settlement within just a few years. Its vision could take advantage of new lab techniques for growing oysters and corals.

As part of the programme, one team at Rutgers University in New Jersey has received $4.5 million to develop defences based on oyster reefs in the Gulf of Mexico near Tyndall Air Force Base. Another team, at the University of Hawaii, received more than $7.3 million to experiment with structures that encourage coral reef growth in the Pacific Ocean. The third team, at the University of Miami, was awarded almost $7.5 million to develop an artificial reef solution with a different species of coral for the Atlantic Ocean.

The research teams must first build artificial reefs, starting at 50 metres in length, before eventually extending them to 150 metres. Early testing in wave tanks is set to eventually lead to a three-year-long deployment offshore between 2023 and 2026.

Researchers will also selectively breed oysters and corals at seawater temperatures 3°C higher than ambient temperatures, so the animals can better survive in a warming world.

“All the teams have expertise in growing oysters and corals in their laboratory environments, selecting for higher temperatures or disease resistance,” says Campbell.