FORT LAUDERDALE, Fla. — South Florida researchers trying to prevent predatory fish from devouring lab-grown coral are turning to biodegradable straws in an effort to restore what some are calling the marine rainforest.
Scientists around the world have been working for years to tackle the decline of coral reef populations. Last summer, reef rescue groups in South Florida and the Florida Keys tried to save coral from rising ocean temperatures. In addition to the work to keep existing coral alive, researchers have also grown new coral in laboratories and then placed them in the ocean.
But protecting the underwater ecosystem that is home to more than 25% of all marine species is not easy. Even more challenging is ensuring that coral grown in a laboratory and placed in the ocean does not become expensive fish food.
Marine researcher Kyle Pisano said one problem is that predators such as parrotfish try to bite and destroy the newly transplanted coral in areas like South Florida, leaving them with a survival rate of less than 40%. With projects requiring thousands of corals to be planted in the next year and tens of thousands of corals in the next decade, losses mount as coral pieces can cost more than $100 each.
Pisano and his partner, Kirk Dotson, developed the Coral Fort and claim that the small biodegradable cage, made partly of straws, increases the survival rate of transplanted coral to more than 90%.
“Parrotfish on the reef really enjoy biting a newly transplanted coral,” Pisano said. “They treat it a bit like popcorn.”
Fortunately, the fish eventually lose interest in the coral as it ages, but scientists must protect the coral in the meantime. In the past, stainless steel and PVC pipe barriers have been placed around transplanted coral, but those barriers had to be cleared of algae growth and ultimately removed.
Pisano came up with the idea of creating a protective barrier that would eventually disappear, eliminating the need to maintain or remove it. He began conducting offshore experiments with biodegradable coral cages as part of a master’s degree at Nova Southeastern University. He used a substance called polyhydroxyalkanoate, a biopolymer derived from the fermentation of canola oil. PHA biodegrades in the ocean, leaving only water and carbon dioxide. His findings were published last year.
The coral cage consists of a limestone disk surrounded by eight vertical Phade brand drinking straws, made by WinCup Inc. from Atlanta. The device has no top, Pisano said, because the young coral needs sunlight and the parrotfish do not. generally want to position themselves face down to eat.
Dotson, a retired aerospace engineer, met Pisano through his professor at Nova Southeastern, and the two formed Reef Fortify Inc. to further develop and market the Coral Fort, for which a patent has been applied for. The first batch of cages cost $12 each, but Pisano and Dotson believe that could change as production increases.
Early prototypes of the cage, made from standard phade straws, were able to protect the coral for about two months before it dissolved into the ocean, but that wasn’t long enough to outlast parrotfish interest. When Pisano and Dotson asked for help, the company assured them that it could custom-make virtually any shape from the biodegradable PHA material.
“But it turns out that the boba straws work just fine right out of the box,” Dotson said.
Boba straws are wider and thicker than normal straws. They are used for a tea-based drink with tapioca balls at the bottom of the cup. For Pisano and Dotson, that extra thickness means the straws last just long enough to protect the growing coral before harmlessly disappearing.
Reef Fortify hopes to work with reef restoration projects around the world. The Coral Forts are already being used by researchers at Nova Southeastern and the University of Miami, as well as the Hawaii Division of Aquatic Resources.
Rich Karp, a coral researcher at the University of Miami, said they have been using the Coral Forts for about a month. He pointed out that doing work underwater takes a lot of time and effort, so having a protective cage that dissolves when it is no longer needed essentially cuts their work in half.
“Simply trapping corals and removing the cages later, that’s twice the amount of work, twice the amount of bottom time,” Karp said. “And it’s not really scalable.”
Experts say coral reefs are an important part of the oceanic ecosystem. They occupy less than 1% of the world’s ocean, but provide food and shelter for almost 25 percent of marine life. Coral reefs also help protect people and their homes along the coastline from storm surges during hurricanes.