A quest to regrow a coral reef

3 January, 2015 6:30 PM

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A quest to regrow  a coral reef

David Vaughan plunges his right arm down to his elbow into one of nine elevated tanks where thousands of tiny colonies of coral are growing at an astonishing rate in shaded seclusion next to the Mote Tropical Research Laboratory in Summerland Key, Florida.

“Now this is the exciting part. You ready for this?” he asks, straining to be heard over the relentless hiss of filtered saltwater squirting from a maze of pipes and plastic tubing into the shallow fiberglass tank, the size of a dining-room table.

Vaughan, a marine biologist who is executive director of the laboratory, retrieves a flat rock from the bottom. A chocolate-brown colony of brain coral, nearly eight inches wide, has grown on the stony surface, its distinctive fleshy, serpentine folds nearly covering the rock.

A year ago the colony began as inch-and-a-half-wide coral fragments cut with a band saw from the same parent colony. As if doused with a growth elixir, these coral “seeds” began to grow 25 times as fast as they would in the wild. And when arranged a few inches apart on the rock, the mini-colonies quickly advanced across the surface and fused to become a single grapefruit-sized organism that continues to grow.

A year ago the colony began as inch-and-a-half-wide coral fragments cut with a band saw from the same parent colony. As if doused with a growth elixir, these coral “seeds” began to grow 25 times as fast as they would in the wild.

Other coral species grown from tiny coral seeds in the Mote lab have developed even faster — up to 50 times their normal rate.

Vaughan and a staff biologist, Christopher Page, say this quick-grow technique, called microfragmenting, may make it possible to mass-produce reef-building corals for transplanting onto dead or dying reefs that took centuries to develop — perhaps slowing or even reversing the alarming loss of corals in the Florida Keys and elsewhere.

Other scientists are excited, too. While there are other efforts around the world to grow new coral, “this is easily the most promising restoration project that I am aware of”, said Billy Causey, a coral expert who oversees all federal marine sanctuaries in the Southeastern United States, the Gulf of Mexico and the Caribbean for the National Oceanic and Atmospheric Administration.

“Dave and Chris are buying us time,” he added. “This will keep corals out there until we can come to understand what is happening to coral on the larger scale.”

A quarter of the Earth’s corals have disappeared in recent decades, and the Mote scientists say no one can predict what will happen if the oceans continue to warm, pollution and acidification increase, overfishing further decimates species beneficial to coral, and runoff from the land continues to reduce the amount of life-giving sunlight that reaches the bottom.

“We do not know if this is a fix-all,” Page said. “At worst, we’re buying a little time. At best, we could restore the ecosystem.”

Vaughan stumbled upon the microfragmenting idea eight years ago. He was transferring colonies of elkhorn coral between aquariums in his lab. He reached to the bottom of a tank to retrieve a colony growing on a two-inch concrete puck.

“Part of the coral had grown over the back side and had attached to the bottom of the aquarium,” he said. When he grabbed it, “it broke off and left two or three polyps behind. I thought I just killed those. But oh, well, I moved the puck over.”

A week later he happened to glance at the abandoned polyps — the individual hydra-shaped, genetically identical organisms that make up a coral colony — on the bottom of the aquarium. “I noticed that those one to three polyps were now five to seven polyps,” he said. “They not only had lived — they had grown and had doubled in size.” It was, he said, “my Eureka mistake”. He cut a few more polyps from the original colony and placed them on other pucks. “And they grew like crazy. The coral seems to want to repair itself quickly and grow back over its lost ground before something else takes its territory.”

But it wasn’t until Page was hired in 2011 that Vaughan first applied this insight to the large-scale production of massive corals.

Page, 29, had raised corals in an aquarium as a teenager in Buffalo, New York. He knew that hobbyists and live-coral dealers routinely split growing colonies into pieces to sell or trade. “It was a chance to apply what I had done on a much larger scale and actually accomplish something big,” he said.

Three years later, he said, he can produce 1,000 microfragments just one centimetre square in four days. And with more space and adequate funding, he added, “the sky’s the limit.”

In June, Mote scientists won federal approval to begin their most ambitious project yet — to create a living coral thicket on the limestone skeleton of a dead reef half a mile off Big Pine Key, just east of Key West.

They have started planting 4,000 nursery-raised corals — symmetrical brain, boulder star, great star and massive starlet — on the 2.5-acre test site. Those species will join more than 1,000 staghorn coral raised in Mote’s offshore nursery by a team led by another staff scientist, Erich Bartels.

The goal, Vaughan said, is to create “in a very short period of time a reef like the reefs we remember” from decades ago.

The project, among the largest coral restorations ever attempted, is the first large-scale effort in the Keys, and one of the few in the world, to restore massive corals in the wild, Vaughan said.

By late October the Mote team had transplanted a total of 720 nursery corals to the offshore site in three separate plantings roughly a month apart.

The first planting, on July 25, was a disaster. Parrotfish found the nursery-raised corals particularly tasty. While some colonies were untouched, most “got chomped”, Page said.

The researchers adjusted their technique. Instead of transplanting corals directly from the nursery to the test site, they temporarily placed them under wire cages near their intended permanent homes.

“They are doing fantastic,” Page said. “Predation significantly decreased after they acclimatised to site conditions” and were then relocated to the test site — perhaps because of subtle shifts in the colour of the colonies, changes in their internal chemistry or other factors.

Colour matters, the scientists found. Predators seemed to pass up darker corals in favour of fluorescent green ones.

Source: indianexpress.com

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