HI - Biorock coral reef proposed for Keonenui Bay in Kahana
KAHANA — The Keonenui Bay Foundation, a 501(c)(3) corporation, is proposing construction of a live barrier coral reef in West Maui’s Keonenui Bay.
This large structure is a steel mesh frame protected by the Biorock mineral accretion technique.
According to the foundation, coral on the frame grows six times faster, is immune to ocean acidification and better survives bleaching.
In just a few years, coral growth and hard calcium carbonate accretion on the metal results in a porous and strong surface that causes large swells to break, dissipating wave energy but allowing sand to deposit on the beach and protecting shoreline structures.
Coral growth can be jump started by attaching fragments of local coral species.
“This is a nature-based solution to beach restoration and shoreline structure protection,” wrote foundation President Michael Lindenfeld, Ph.D.
Biorock reefs have been built for decades by the Global Coral Reef Alliance in around 40 countries and have restored beaches every time they were designed appropriately. The validated design follows that of actual coral reefs in Hawaii, where coral reefs have been protecting beaches for millions of years.
Wave dissipation measurements on Molokai showed that the reef top should be within 2 feet of the surface, the width be at least 50 feet, and that the leading edge facing the incoming wave be steep.
The Keonenui Bay Foundation welcomes comments and questions from the community.
For Biorock information, see the Global Coral Reef Alliance website
These dimensions ensure that large swell steepens and then breaks. Thus, the Biorock reef works like a permeable, submerged breakwater, but it’s inexpensive and contains live coral that feeds fish.
“Steel rusting is prevented and mineral deposition occurs due to a harmless, about one- volt direct electrical current turning water next to the frame alkaline. Using dissolved carbon dioxide and calcium ions, calcium carbonate is deposited on the frame as aragonite, three times stronger than concrete, and is also taken up by the coral. The current is not felt by or affects any marine creature or person,” Lindenfeld noted.