sffrenchman
Contributor
- Messages
- 265
- Reaction score
- 30
- # of dives
- 500 - 999
I thought that you may be interested in the following article on reef restoration published in Science Magazine.
C.
Science 31 July 2009:
Vol. 325. no. 5940, pp. 559 - 561
DOI: 10.1126/science.325_559
NEWS:
Bringing Coral Reefs Back From the Living Dead
Dennis Normile
A smattering of efforts are aiming to prove that degraded coral reefs can be restored to functionality, if not pristine beauty.
ISHIGAKI, JAPANLast April on the northern edge of Sekisei Lagoon, Japan's largest coral reef, five divers placed dozens of stainless steel cages packed with custom-made ceramic disks on the sea floor near a patch of healthy coral in the ailing reef. All had to be ready before a mass spawning event expected during the new moon in May, in hopes that millions of coral larvae would settle on the disks. The high-tech operation went according to plan, and earlier this month the divers moved the cages to sheltered lagoon waters to enable the larvae to mature and form colonies. In another 18 months or so, the disks will be cemented into parts of the reef where a process known as bleaching, triggered by unusually warm waters, had killed the coral. In 30 years or so, researchers hope, the 27,000-hectare reef will be fully restored.
One year earlier and 1000 kilometers to the southwest, the Philippine coastal community of Bolinao set out to restore its bleached and overfished reef. Residents decked out in homemade plywood flippers dove without air tanks from outrigger canoes. They broke off fragments of a robust coral from one part of the reef and wedged pieces into cracks in bleached sections. Six months later they returned, snapped off bits of the healthy transplanted coral, and repeated the process.
The Bolinao reef restoration may be the most inexpensive in the world, whereas that in Sekisei Lagoon is probably the costliest. But both projects are important experiments in an urgent effort to stabilize the world's embattled coral reefs, which provide habitat for some 9 million species, including 4000 kinds of fish. Roughly 100 million people in developing countries depend on reefs for subsistence fishing and tourism, estimates the Global Environmental Facility (GEF). The "rainforests of the sea," however, are threatened by human activity and natural disasters. About 19% of our planet's original global coral reef area has been destroyed; another 15% could be lost in the next 2 decades, according to the Global Coral Reef Monitoring Network's Status of Coral Reefs of the World: 2008.
As losses mount, restoration projects are only just getting off the ground. "The science of reef restoration is in its infancy," says Alasdair Edwards, a reef scientist at Newcastle University in New-castle upon Tyne, U.K. "There are tens of thousands of square kilometers of degraded reefs apparently out there, and almost all restoration trials are working at subhectare scales." The immediate challenge, he and others say, is to show that promising techniques can be scaled up. That will require resources that are by no means guaranteed: A good share of recent restoration projects has been funded by GEF's Coral Reef Targeted Research program, which ends this year.
Some experts are skeptical that restoration can make much of a difference. Healthy reefs lightly disturbed by humans typically recover from bleaching and natural disasters on their own, Edwards notes. But reefs pummeled by pollution, destructive fishing practices, or land reclamation are often pushed beyond recovery by bleaching or storms. "The only way to help is to reduce stresses that made [such reefs] degrade in the first place," says David Fisk, a coral reef scientist and consultant in Geneva.
Saving Sekisei
The daunting challenges facing restoration scientists are evident at Sekisei Lagoon, cradled by Ishigaki and Iriomote, the two southernmost large islands of Okinawa prefecture. Sekisei's predicament has been documented by Mineo Okamoto, a specialist in marine assessment techniques at Tokyo University of Marine Science and Technology, who in 1993 started mapping coral in the lagoon using echo sounders and cameras to add detail to satellite images. Back then, Sekisei was in pristine condition, thanks to its remote location and status as a national park. But Okamoto sensed that change was coming from global warming, with its threat of more-frequent bleaching events, and rising ocean acidification, which is caused by the uptake of carbon dioxide from the atmosphere and weakens corals (Science, 4 May 2007, p. HYPERLINK "http://www.sciencemag.org/cgi/content/full/sci;316/5825/678" 678). Okamoto set out to document how such climate changes affect a coral reef.
Okamoto completed his first coral map in 1998. That year an El Niño followed by a La Niña warmed the eastern Pacific to the point that zooxanthellaealgae that live symbiotically with coral and provide nutrientsdeserted their hosts. Without zooxanthellae, corals blanch and unless the algae return within a few weeks, the colony starves and perishes. The 1998 bleaching event killed 16% of corals worldwide (Science, 27 October 2000, p. HYPERLINK "http://www.sciencemag.org/cgi/content/full/sci;290/5492/682" 682).
Sekisei Lagoon's northern edge was hit hard. But the interior and southern rim were spared, which enabled coral to recolonize bleached sections without human intervention. Three bleaching events since 2001 devastated the interior and southern sections even as the northern rim recovered. But prevailing currents tend to sweep larvae produced on the northern edge away from the lagoon, impeding recolonization of recently damaged areas.
To speed the reef's recovery, Okamoto custom-made ceramic disks with grooves on the undersides that coral larvae can nestle in while avoiding algae that foul the disks' tops. Okamoto placed limited numbers of diskswhich are small enough to fit in the palm of a handin the lagoon in 2002. Two years later, Japan's environment ministry made Sekisei Lagoon's restoration "a big public works project" and bestowed a budget of about $430,000 a year, says Okamoto, who now serves as a consultant. Teams have been placing cages filled with disks along the ocean side of the reef's 10-kilometer-long northern rim before the annual mass coral spawning. Months later, they move disks hosting juveniles to the lagoon's interior, where the corals mature. Okamoto estimates that the May 2008 spawning yielded about 10,000 colonies that will be placed on the lagoon's southern edge in December.
"We have set a long-term period of 30 years for this restoration project," says Takanori Satoh, a ranger for the ministry's Coral Reef Research and Monitoring Center in Ishigaki. In 7 or 8 years, he says, researchers will be able to ascertain whether larvae from the transplanted corals have begun to recolonize the lagoon's interior.
Economizing
Few projects can expect such unstinting support as Sekisei. "At the end of the day, [reef restoration] has got to be something low-cost and low-tech that involves the local communities," says Edgardo Gomez, a marine biologist at the University of the Philippines in Diliman, who has worked with fishers in Bolinao, where the university has a marine lab, to restore reefs. Degraded by decades of blast fishing, Bolinao's reefs were devastated by the 1998 bleaching and have recovered only spottily. "The fish catch greatly diminished, and people had to resort to other ways of making a living," Gomez says.
To restore the reef, Gomez needed to find a coral species that thrives even when handled roughly. "The villagers can't afford adhesives, and nobody in the town of Bolinao, save for the dive shop, has scuba equipment," Gomez says. He settled on Porites cylindrica, a fast-growing branching coral. During their first training workshop in April 2008, Bolinao spear fishers planted about 400 square meters of reef. Six months later, 80% of transplanted coral was growing nicely and was big enough for bits to be broken off to replant another 400 square meters. The process was repeated in spring 2009. "If we keep doubling the areas we are restoring, in time it will become significant," Gomez says.
Gomez is planning to introduce these methods elsewhere in the Philippines and in other countries. He admits that the patched-up reefs will lack the diversity of natural reefs. "What is most important is that you build back the [roughness] of the reef so fish and invertebrates have refuges," he says. The promise of a healthy fishery gives locals an incentive to stick with an effort that may take years before they see a payoff.
Another approach to restoration on the cheap is what Baruch Rinkevich, a marine biologist at the National Institute of Oceanography in Haifa, Israel, calls "underwater silviculture." Just as foresters rear trees in nurseries for transplantation, Rinkevich and colleagues have pioneered coral nurseries: mesh nets or even lengths of rope raised off the sea floor to avoid predators and sedimentation. Students, technicians, or local fishers collect donor corals, chop them into nubbins as small as 0.5 centimeters across, and glue these onto a substrateanything from seashells to bits of plastic pipingthat is then attached to the nursery nets. Rinkevich says up to 99% of nubbins survive, depending on the species, and 12 to 18 months later they are big enough to transplant onto a reef.
Rinkevich worked out the kinks of the technique in Eilat, on the Red Sea, starting in the mid-1990s. More recently, he has experimented in Jamaica, the Philippines, Singapore, Thailand, and Zanzibar. "The results are more than just promising; they are beautiful," he says. Rinkevich claims that under optimal conditions in countries with cheap labor, he can produce a colony ready for transplantation for as little as 18 cents. So far, Rinkevich has built nurseries with 10,000 corals and transplanted up to 3000 colonies. He envisions nurseries with up to 200,000 corals and similarly supersized transplantations. "By doing that, I'm pretty sure we can change completely denuded reefs," he says. Newcastle's Edwards agrees that nurseries are one of the most promising approaches. "You're minimizing the collateral damage [by cutting donor material into small pieces], getting transplants, and maximizing the effect you can have," he says.
One drawback is that a reliance on nubbins from a single donor coral results in limited genetic diversity. To address that, Rinkevich and others are investigating a variation on the theme in which they capture eggs and sperm from the ocean during mass spawning events or from colonies taken into the lab just before spawning (Science, 14 December 2007, p. HYPERLINK "http://www.sciencemag.org/cgi/content/full/sci;318/5857/1715" 1715). The gametes are mixed, and the resulting larvae settle onto substrates in tanks. The juvenile corals are moved into the nursery and transplanted to a reef a year or so later. Although this procedure boosts genetic diversity, it is more costly than nubbins and requires more expertise.
One recent trial in the Philippines led by James Guest, a marine biologist at the National University of Singapore, yielded about 1.6 million larvae from 19 colonies in tanks with 2000 concrete pins as substrates. Based on work in 2008, they expect about 1000 colonies to survive the first year. "We still have lots of work to do to improve these survival levels," Guest says.
Another approach is more like animal husbandry than silviculture. Researchers have "got a bit of a handle on the process of sexual reproduction in corals," which opens up the possibility of manipulating larvae, says Andrew Heyward, a coral reproductive specialist at the Australian Institute of Marine Science in Perth.
In a 2008 experiment in Palau, Heyward's team collected gametes from lab colonies and cultured larvae in improvised tanks: aboveground swimming pools. Each day they tested a few larvae to see if these were ready to settle and form a colony by exposing them to a reef chemical that triggers settlement in "competent" larvae. When half the batch was primed to settle, the researchers funneled larvae into an enclosure over an artificial reef. Six months later, they found five times as many juvenile corals on the treated rock as on nearby rocks that relied on natural recruitment. The equation is simple, says Heyward: More larvae in a given area mean better recruitment. "It takes almost no technology," he says.
With the future of reefs hanging in the balance, coral scientists are eagerly following the nascent restoration efforts. The various techniques being deployed "are still basically unproven in the long term," Edwards cautions. Fisk in Geneva is pessimistic about any restoration effort reaching a critical scale that would make a reef resilient. "You can't build big enough to withstand natural and manmade disturbances," he says.
Others insist that reef restoration will ultimately prevail. Rinkevich compares reef rehab to terrestrial reforestation. Although most present-day forests in North America and Europe are human cultivated, they nonetheless provide habitat for wildlife and prevent soil erosion. "In similar ways, transplanted corals change the environment in an area around a reef: Fish arrive, and invertebrates arrive," Rinkevich says. The detrimental impact of global warming and rising ocean acidification is "going to get worse before it gets better," adds Gomez. But "waging a rear-guard action" through restoration should lessen the harm inflicted on reefs and on livelihoods.
Such debates might be settled "as soon as someone can come up with a large-scale restoration that has worked," says Edwards. It may be up to Sekisei Lagoon and bootstrapping community efforts to prove that the world's battered coral reefs can be saved.
C.
Science 31 July 2009:
Vol. 325. no. 5940, pp. 559 - 561
DOI: 10.1126/science.325_559
NEWS:
Bringing Coral Reefs Back From the Living Dead
Dennis Normile
A smattering of efforts are aiming to prove that degraded coral reefs can be restored to functionality, if not pristine beauty.
ISHIGAKI, JAPANLast April on the northern edge of Sekisei Lagoon, Japan's largest coral reef, five divers placed dozens of stainless steel cages packed with custom-made ceramic disks on the sea floor near a patch of healthy coral in the ailing reef. All had to be ready before a mass spawning event expected during the new moon in May, in hopes that millions of coral larvae would settle on the disks. The high-tech operation went according to plan, and earlier this month the divers moved the cages to sheltered lagoon waters to enable the larvae to mature and form colonies. In another 18 months or so, the disks will be cemented into parts of the reef where a process known as bleaching, triggered by unusually warm waters, had killed the coral. In 30 years or so, researchers hope, the 27,000-hectare reef will be fully restored.
One year earlier and 1000 kilometers to the southwest, the Philippine coastal community of Bolinao set out to restore its bleached and overfished reef. Residents decked out in homemade plywood flippers dove without air tanks from outrigger canoes. They broke off fragments of a robust coral from one part of the reef and wedged pieces into cracks in bleached sections. Six months later they returned, snapped off bits of the healthy transplanted coral, and repeated the process.
The Bolinao reef restoration may be the most inexpensive in the world, whereas that in Sekisei Lagoon is probably the costliest. But both projects are important experiments in an urgent effort to stabilize the world's embattled coral reefs, which provide habitat for some 9 million species, including 4000 kinds of fish. Roughly 100 million people in developing countries depend on reefs for subsistence fishing and tourism, estimates the Global Environmental Facility (GEF). The "rainforests of the sea," however, are threatened by human activity and natural disasters. About 19% of our planet's original global coral reef area has been destroyed; another 15% could be lost in the next 2 decades, according to the Global Coral Reef Monitoring Network's Status of Coral Reefs of the World: 2008.
As losses mount, restoration projects are only just getting off the ground. "The science of reef restoration is in its infancy," says Alasdair Edwards, a reef scientist at Newcastle University in New-castle upon Tyne, U.K. "There are tens of thousands of square kilometers of degraded reefs apparently out there, and almost all restoration trials are working at subhectare scales." The immediate challenge, he and others say, is to show that promising techniques can be scaled up. That will require resources that are by no means guaranteed: A good share of recent restoration projects has been funded by GEF's Coral Reef Targeted Research program, which ends this year.
Some experts are skeptical that restoration can make much of a difference. Healthy reefs lightly disturbed by humans typically recover from bleaching and natural disasters on their own, Edwards notes. But reefs pummeled by pollution, destructive fishing practices, or land reclamation are often pushed beyond recovery by bleaching or storms. "The only way to help is to reduce stresses that made [such reefs] degrade in the first place," says David Fisk, a coral reef scientist and consultant in Geneva.
Saving Sekisei
The daunting challenges facing restoration scientists are evident at Sekisei Lagoon, cradled by Ishigaki and Iriomote, the two southernmost large islands of Okinawa prefecture. Sekisei's predicament has been documented by Mineo Okamoto, a specialist in marine assessment techniques at Tokyo University of Marine Science and Technology, who in 1993 started mapping coral in the lagoon using echo sounders and cameras to add detail to satellite images. Back then, Sekisei was in pristine condition, thanks to its remote location and status as a national park. But Okamoto sensed that change was coming from global warming, with its threat of more-frequent bleaching events, and rising ocean acidification, which is caused by the uptake of carbon dioxide from the atmosphere and weakens corals (Science, 4 May 2007, p. HYPERLINK "http://www.sciencemag.org/cgi/content/full/sci;316/5825/678" 678). Okamoto set out to document how such climate changes affect a coral reef.
Okamoto completed his first coral map in 1998. That year an El Niño followed by a La Niña warmed the eastern Pacific to the point that zooxanthellaealgae that live symbiotically with coral and provide nutrientsdeserted their hosts. Without zooxanthellae, corals blanch and unless the algae return within a few weeks, the colony starves and perishes. The 1998 bleaching event killed 16% of corals worldwide (Science, 27 October 2000, p. HYPERLINK "http://www.sciencemag.org/cgi/content/full/sci;290/5492/682" 682).
Sekisei Lagoon's northern edge was hit hard. But the interior and southern rim were spared, which enabled coral to recolonize bleached sections without human intervention. Three bleaching events since 2001 devastated the interior and southern sections even as the northern rim recovered. But prevailing currents tend to sweep larvae produced on the northern edge away from the lagoon, impeding recolonization of recently damaged areas.
To speed the reef's recovery, Okamoto custom-made ceramic disks with grooves on the undersides that coral larvae can nestle in while avoiding algae that foul the disks' tops. Okamoto placed limited numbers of diskswhich are small enough to fit in the palm of a handin the lagoon in 2002. Two years later, Japan's environment ministry made Sekisei Lagoon's restoration "a big public works project" and bestowed a budget of about $430,000 a year, says Okamoto, who now serves as a consultant. Teams have been placing cages filled with disks along the ocean side of the reef's 10-kilometer-long northern rim before the annual mass coral spawning. Months later, they move disks hosting juveniles to the lagoon's interior, where the corals mature. Okamoto estimates that the May 2008 spawning yielded about 10,000 colonies that will be placed on the lagoon's southern edge in December.
"We have set a long-term period of 30 years for this restoration project," says Takanori Satoh, a ranger for the ministry's Coral Reef Research and Monitoring Center in Ishigaki. In 7 or 8 years, he says, researchers will be able to ascertain whether larvae from the transplanted corals have begun to recolonize the lagoon's interior.
Economizing
Few projects can expect such unstinting support as Sekisei. "At the end of the day, [reef restoration] has got to be something low-cost and low-tech that involves the local communities," says Edgardo Gomez, a marine biologist at the University of the Philippines in Diliman, who has worked with fishers in Bolinao, where the university has a marine lab, to restore reefs. Degraded by decades of blast fishing, Bolinao's reefs were devastated by the 1998 bleaching and have recovered only spottily. "The fish catch greatly diminished, and people had to resort to other ways of making a living," Gomez says.
To restore the reef, Gomez needed to find a coral species that thrives even when handled roughly. "The villagers can't afford adhesives, and nobody in the town of Bolinao, save for the dive shop, has scuba equipment," Gomez says. He settled on Porites cylindrica, a fast-growing branching coral. During their first training workshop in April 2008, Bolinao spear fishers planted about 400 square meters of reef. Six months later, 80% of transplanted coral was growing nicely and was big enough for bits to be broken off to replant another 400 square meters. The process was repeated in spring 2009. "If we keep doubling the areas we are restoring, in time it will become significant," Gomez says.
Gomez is planning to introduce these methods elsewhere in the Philippines and in other countries. He admits that the patched-up reefs will lack the diversity of natural reefs. "What is most important is that you build back the [roughness] of the reef so fish and invertebrates have refuges," he says. The promise of a healthy fishery gives locals an incentive to stick with an effort that may take years before they see a payoff.
Another approach to restoration on the cheap is what Baruch Rinkevich, a marine biologist at the National Institute of Oceanography in Haifa, Israel, calls "underwater silviculture." Just as foresters rear trees in nurseries for transplantation, Rinkevich and colleagues have pioneered coral nurseries: mesh nets or even lengths of rope raised off the sea floor to avoid predators and sedimentation. Students, technicians, or local fishers collect donor corals, chop them into nubbins as small as 0.5 centimeters across, and glue these onto a substrateanything from seashells to bits of plastic pipingthat is then attached to the nursery nets. Rinkevich says up to 99% of nubbins survive, depending on the species, and 12 to 18 months later they are big enough to transplant onto a reef.
Rinkevich worked out the kinks of the technique in Eilat, on the Red Sea, starting in the mid-1990s. More recently, he has experimented in Jamaica, the Philippines, Singapore, Thailand, and Zanzibar. "The results are more than just promising; they are beautiful," he says. Rinkevich claims that under optimal conditions in countries with cheap labor, he can produce a colony ready for transplantation for as little as 18 cents. So far, Rinkevich has built nurseries with 10,000 corals and transplanted up to 3000 colonies. He envisions nurseries with up to 200,000 corals and similarly supersized transplantations. "By doing that, I'm pretty sure we can change completely denuded reefs," he says. Newcastle's Edwards agrees that nurseries are one of the most promising approaches. "You're minimizing the collateral damage [by cutting donor material into small pieces], getting transplants, and maximizing the effect you can have," he says.
One drawback is that a reliance on nubbins from a single donor coral results in limited genetic diversity. To address that, Rinkevich and others are investigating a variation on the theme in which they capture eggs and sperm from the ocean during mass spawning events or from colonies taken into the lab just before spawning (Science, 14 December 2007, p. HYPERLINK "http://www.sciencemag.org/cgi/content/full/sci;318/5857/1715" 1715). The gametes are mixed, and the resulting larvae settle onto substrates in tanks. The juvenile corals are moved into the nursery and transplanted to a reef a year or so later. Although this procedure boosts genetic diversity, it is more costly than nubbins and requires more expertise.
One recent trial in the Philippines led by James Guest, a marine biologist at the National University of Singapore, yielded about 1.6 million larvae from 19 colonies in tanks with 2000 concrete pins as substrates. Based on work in 2008, they expect about 1000 colonies to survive the first year. "We still have lots of work to do to improve these survival levels," Guest says.
Another approach is more like animal husbandry than silviculture. Researchers have "got a bit of a handle on the process of sexual reproduction in corals," which opens up the possibility of manipulating larvae, says Andrew Heyward, a coral reproductive specialist at the Australian Institute of Marine Science in Perth.
In a 2008 experiment in Palau, Heyward's team collected gametes from lab colonies and cultured larvae in improvised tanks: aboveground swimming pools. Each day they tested a few larvae to see if these were ready to settle and form a colony by exposing them to a reef chemical that triggers settlement in "competent" larvae. When half the batch was primed to settle, the researchers funneled larvae into an enclosure over an artificial reef. Six months later, they found five times as many juvenile corals on the treated rock as on nearby rocks that relied on natural recruitment. The equation is simple, says Heyward: More larvae in a given area mean better recruitment. "It takes almost no technology," he says.
With the future of reefs hanging in the balance, coral scientists are eagerly following the nascent restoration efforts. The various techniques being deployed "are still basically unproven in the long term," Edwards cautions. Fisk in Geneva is pessimistic about any restoration effort reaching a critical scale that would make a reef resilient. "You can't build big enough to withstand natural and manmade disturbances," he says.
Others insist that reef restoration will ultimately prevail. Rinkevich compares reef rehab to terrestrial reforestation. Although most present-day forests in North America and Europe are human cultivated, they nonetheless provide habitat for wildlife and prevent soil erosion. "In similar ways, transplanted corals change the environment in an area around a reef: Fish arrive, and invertebrates arrive," Rinkevich says. The detrimental impact of global warming and rising ocean acidification is "going to get worse before it gets better," adds Gomez. But "waging a rear-guard action" through restoration should lessen the harm inflicted on reefs and on livelihoods.
Such debates might be settled "as soon as someone can come up with a large-scale restoration that has worked," says Edwards. It may be up to Sekisei Lagoon and bootstrapping community efforts to prove that the world's battered coral reefs can be saved.
