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.

Broward Segment II FONSI & EA are inadequate and should be rejected

June 14 2014

To: Eric P. Summa, Chief, Environmental Branch, Planning and Policy Division, US Army Corps of Engineers, Jacksonville District

From: Thomas J. Goreau PhD, President, Global Coral Reef Alliance

Re: Finding of No Significant Harm for Broward Segment II Beach Project and failure to require an Environmental Impact Statement
The US Army Corps of Engineers (ACE) issued on August May 14 2014 a Finding Of No Significant Impact (FONSI) and an Environmental Assessment (EA) for the placement of sand on Broward County Segment II, and stated that this project “will have no significant impact on the quality of the human environment”, that it “will not jeopardize the continued existence of any threatened or endangered species of adversely impact any designated “critical habitat”” and therefore “does not require an Environmental Impact Statement”.

The first two claims are entirely incorrect, and therefore the failure to require a full environmental impact assessment amounts to dereliction of ACE’s responsibility to the public.

The coral reefs of the hard ground ridge closest to the beach from Lauderdale-By-The-Sea (LBTS) to the Port Everglades channel have the largest area and highest live coral cover of any coral reefs now remaining in Florida, and the only ones that can be swum to from shore.

These reefs have spectacular forests of endangered and threatened staghorn coral (Acropora cervicornis), elkhorn coral (Acropora palmata) and huge ancient colonies of pillar coral (Dendrogyra cylindrus), star coral (Montastrea annularis), great star coral (Montastrea cavernosa), and more than a dozen additional reef building coral species.

The best reef is on the ridge closest to the beach, with up to around 40% live coral cover, almost certainly the largest area of coral remaining in Florida. This reef and was entirely unknown to the scientific community until it was first described by T. J. Goreau & D. Clark, 2001, Reef Protection in Broward County, Florida, Global Coral Reef Alliance White Paper:

This fundamental study is not cited. The reason the reef was unknown to Florida reef scientists and coral reef monitoring programs until then was because they dived from boats, and dived only on the reef ridges further from the beach, which average only around 1% live coral cover. Nevertheless the reef was well known to shore divers because it was closest to shore. This area is where the reefs come closest to shore, and are therefore most vulnerable to being buried by sand and damaged by turbidity from fill dumped on the beaches.

Most importantly the coral reef area nearest to the beach is overwhelmingly dominated by the endangered staghorn coral, Acropora cervicornis, which is THE MOST SEDIMENT SENSITIVE CARIBBEAN CORAL SPECIES. No discussion is made of the abundance of this coral or it’s extreme sensitivity to sediments in this document!

The stretch of beach from LBTS to Port Everglades is the only remaining nearshore coral reef habitat in Southeast Florida because it is the only stretch of shore where sand has not been dumped on the beaches. In all other parts of SE Florida the nearshore reefs were killed when they were damaged by dredged sand dumped on the beaches, and no prior baseline studies were ever done in those areas. Only the oldest divers now remember the magnificent reefs that were killed. The reef adjacent to Segment II is the last remaining nearshore reef in SE Florida.

The claim by ACE that there will be no damage to the adjacent endangered and threatened species habitats is based on the claim that the sand will not move from the beach and bury the adjacent hardground. This is based on mathematical models that “show” that the sand will not move beyond an “equilibrium toe of fill”, but this result is due to faulty mathematical assumptions in models that consider average conditions, but do not include hurricanes or winter storms. The fact is that in every other place where sand was dumped on the beach the sand quickly buried the nearshore hardground and killed the corals, as the old divers can tell them.

There are many erroneous statements regarding coral reefs in this document. Specifically some of the most egregious are:

1. Once again the claim is made (page 75) that there will be no sediment movement beyond the Equilibrium Toe Of Fill. This is an artificial line that has no natural basis in reality whatsoever, being purely the artifact of a totally inadequate mathematical model that does not describe reality at all, because this model represents average conditions and does not include hurricanes or winter storms, which are consistently observed to bury offshore hardgrounds next to beach dredge-fill dumping (“renourishment”) projects. I have personally observed this on Broward Segment III and Broward Segment I, and USACE promised that no dredge-fill dumping would be allowed on Segment II unless the environmental impact assessments of Segments III and I showed no hardground burial. Why has this promise been ignored and why was the burial of hardground communities in those areas not documented in the EA and FONSI? The amount of sand dumped on the beach is well known, and most of it was immediately eroded away, even before the dumping was finished. The beach profiles before, during, and after should have been documented. Why were they not used to calculate the mass balance of the sand dumped, that which remained, and that which was eroded away to adjacent habitats?

2. The irresponsible claim (page 83) that sediment will cause no harm to staghorn coral is totally false (see above), and the claim that dumping sand will cause more erosion that will uncover more previously buried hardground is reductio ad absurdum.

3. The claim (page 103) that this project does not violate E.O. 13089 is clearly false because of 2 above.

4. The alleged “mitigation” is a costly joke, because the laboratories involved and the methods they use simply won’t work in the medium or long term.

5. The best coral reef restoration project in Florida, the Lauderdale-By-The-Sea Biorock project, which has around 40% live coral cover, is directly threatened by the proposed Segment II beach dredge-fill dumping project. That is to say at a time when corals are under severe threat, efforts made to restore them may be destroyed by this project.

In effect ACE, by accepting this grossly inadequate EA, has buried its head in the sand by denying the impacts this sand will have in burying the immediately adjacent areas of the best populations of threatened and endangered coral reef species left in Florida. This is a serious dereliction of their public responsibility in an age of environmental awareness, and a violation of E.O 13089.

We cannot allow the last good nearshore reefs in SE Florida to be killed like all the rest! We call on the Army Corp of Engineers to revoke this irresponsible “Finding Of No Significant Impact” and failure to require a full Environmental Impact Statement.