Biorock electric coral reefs survive the most severe hurricanes with little or no damage

Two new Global Coral Reef Alliance videos answer the question many people have: what happens in a hurricane? Here we show that Biorock reefs hit by the eye of three of the strongest Caribbean hurricanes, Hanna, Ike, and Irma, suffered almost no physical damage and built up sand around them during the event.

In contrast, solid concrete objects nearby caused so much scour and erosion around and under them that they sank into the sand. Solid breakwaters cause reflection of waves at the solid surface, concentrating all the wave energy in one plane, which causes sand to wash away in front of the structure, then underneath, until it is undermined and collapses. This is the inevitable fate of any vertical seawall, so they need constant and costly repair and replacement. After Hurricane Andrew every single shipwreck in South Florida was torn apart or moved great distances due to the strong surface drag. Not one remained intact.

Biorock electric coral reefs can be any size or shape. For growing corals, we make open frameworks, so the corals can benefit from the water flow through the structure, just as they do in coral reef. As a result of their low cross section to waves, they dissipate energy by surface friction as waves pass through them, refracting and diffracting waves rather than reflecting them. Their low drag coefficient means that they survive waves that would move or rip apart a solid object of the same size.

Here we show what happened to Biorock reefs after the most severe hurricanes ever to hit Saint Barthelemy and Grand Turk. Incredibly, there was little or no physical damage to the structures or to the corals, even though these structures were not welded, simply wired together by hand, and they were not physically attached to the bottom, simply sitting on the bottom under their own weight, attaching themselves to hard bottoms and cementing sand around their bases through growth of limestone rock over their surfaces.

Saint Barthelemy:

Grand Turk:

These astonishing results follow our previous video showing the record recovery of severely eroded beaches behind Biorock reefs:

Scientific papers documenting the Grand Turk results are at: Effect of severe hurricanes on Biorock Coral Reef Restoration Projects in Grand Turk, Turks and Caicos Islands

and the rapid restoration of the beach at: Biorock Electric Reefs Grow Back Severely Eroded Beaches in Months

It is important to realize that neither rocks nor structures exposed at low tide shown in this video are an essential part of the method. Almost all of Biorock structures are completely submerged and have no rocks. At Pulau Gangga this design was used to protect the beach from storms at high tide, and effectiveness was more important than aesthetics to the Resort, so they opted not to have what most people want: an invisible watchman that you can’t see at low tide sunset!

In addition, Biorock electric reefs greatly increase the settlement, growth, survival, and resistance to stress of all marine organisms, with only a single known exception: predatory sharks avoid electric fields that confuse them, protecting people and sharks from each other (Uchoa, O’Connell, & Goreau, 2017). In 2016 there was nearly complete survival of Biorock corals during severe high-temperature events that bleached and killed more than 95% of corals on nearby reefs.

Our results show that Biorock electric reefs are the most cost-effective method for saving corals from global warming, restoring reef communities (whether corals, oysters, or mussels), and protecting coastlines from erosion and global sea level rise.