Archive for the ‘Coral reefs’ Category

Global Bleaching of Corals. Again

Thursday, October 22nd, 2015

When water temperatures rise a degree or two, corals expel their symbiotic algae – zooxanthellae – and turn white. It happens frequently on a local scale, and the affected corals usually recover when the sea cools again.

When bleaching occurs, symbiotic algae are lost, the coral (this one is a brain coral) will die and crumble unless sea temperature drops and the zooxanthellae can recolonize the coral (compareinnovationtoronto.com)

When bleaching occurs, symbiotic algae are lost, the coral (this one is a brain coral) will die and crumble unless sea temperature drops and the zooxanthellae can recolonize the coral (compareinnovationtoronto.com)

Summer sea surface temperature just one degree warmer than usual, lasting for 4-6 weeks, is enough to start the bleaching – corals clearly live, and thrive, at temperatures close to those that bleach and kill them.

When much of the sea surface around the tropics remains warmer for a prolonged period, the bleaching spreads, corals die and reefs are heavily damaged. The last really major global bleaching event occurred in 1997-98, while a less extensive one occurred in 2010.

A now iconic picture of part of a reef in Samoa taken before and after the onset of the current global bleaching event (sciencealert.com)

A now iconic picture of part of a reef in Samoa taken before and after the onset of the current global bleaching event (sciencealert.com)

And now, starting before the current El Nino emerged and compounded by the huge, warm ‘Pacific Blob’, we are well into another global bleaching event. With the current El Nino now growing into something fierce, this bleaching event could last a couple of years, long enough to kill and crumble a lot of the corals.

NOAA has produced a remarkable, satellite-based interactive global coral watch website, where you can observe the conditions change over the next few months. It’s scary, but it’s fascinating.

Coral bleaching isn’t new, but the 1997-1998 event was the greatest in hundreds, perhaps thousands of years. Now we have another of the same or greater magnitude. Again most reefs will be damaged. Last time, global loss was about 10%. This time it will be as much or more. It is a devastating prognosis.

NOAA October 2015 prediction of 60% probability of coral bleaching over the next four months (coralwatch.noaa.gov)

NOAA October 2015 prediction of 60% probability of coral bleaching over the next four months (coralwatch.noaa.gov)

Some protective efforts that would reduce other sources of stress on the reefs are possible, for instance reducing both pollution and overfishing, especially of algal grazers. Closing reefs to all fishing would be best. Unlikely perhaps, but not impossible.

We can as well look for other lines of hope. For instance, corals vary latitudinally in their tolerance of thermal stress, and there appears to be a genetic basis to this variation. In tanks at the National Sea Simulator at Melbourne, biologists are growing different strains of coral species under conditions of warmer temperatures and higher acidity, hoping to select for those more tolerant of the coming conditions, planning then to seed them back on the reefs. Of course this is worth doing.

Sea surface temperatures have been higher than normal for the past year, not related to the Pacific Blob or to El Nino. Now they will remain high or higher as the El Nino heat spreads and lingers (dnlr.hawaii.gov)

Sea surface temperatures have been higher than normal for the past year, not related to the Pacific Blob or to El Nino. Now they will remain high or higher as the El Nino heat spreads and lingers (dnlr.hawaii.gov)

Yet the Great Barrier Reef covers 135,000 square miles and since 1985 half of its coral cover has been lost; little remains of Caribbean coral reefs; the coral reefs around Hawaii and elsewhere in the Pacific have never been under such stress. The future of coral reefs is really bleaker than ever.

For now, the Pacific Blob will eventually dissipate. The new El Nino will slowly play itself out. Sea temperatures will drop back at least in the direction of normal. Parts of coral reefs not too damaged should slowly recover once again.

But we are warned: sea temperatures rising because of climate change rather than El Ninos will not revert to past ‘normal’ temperatures. At best their rise can be slowed by enlightened global agreement to curtail the emission of greenhouse gases,

The current global coral bleaching event is growing as we head into December’s UN Conference on Climate Change in Paris – a conference that is perilously close to being our last chance to take significant global action. Threatened, damaged, bleaching, crumbling coral reefs are not a bad metaphor for the state of our planet’s climate to remind global politicians that no longer can we afford politics as usual.

 The very odd logo for the UN Conference on Climate Change, COP 21, Nov 30-Dec11: the whole world will be watching (unfccc.int)

The very odd logo for the UN conference on Climate Change, COP 21, Nov 30-Dec11: the whole world will be watching (unfccc.int)

They – we – really have to do it this time.

The Partial Recovery of Coral Reefs.

Wednesday, May 27th, 2015

The damage to coral reefs varies of course. It’s greatest in the Caribbean and the Western Pacific – Indonesia, PNG, the Philippines, Guam. It’s least where humans can’t easily get to them – near isolated islands like Pitcairn and Easter, and around atolls scattered in the Pacific, hundreds of km from human communities.

A coral reef in the Philippines, reduced to rubble, similar to many in the Caribbean (wwf.org)

A coral reef in the Philippines, reduced to rubble, similar to many in the Caribbean (wwf.org)

Pristine reefs, with angel fish, healthy corals, even top predators, are now very rare, existing isolated far from human communities (kidsdiscover.com)

Pristine reefs, with angel fish, healthy corals, even top predators, are now very rare, exist isolated far from human communities (kidsdiscover.com)

And that variation is intriguing. If we reduced the stresses we can actually control – pollution, destruction and overfishing – will that make the reefs more resilient to the challenges of climate change? We can find out only by reducing those stresses.

Meanwhile, what happens to a reef, not wrecked by pollution and other destructive events, if overfishing is reduced? Will it recover any? some? all? of its lost ecological complexity? Marine Protected Areas (MPAs) that are large, old and isolated are recognized to be the ideal solution, but in much of the tropics where humans live in any abundance they are impractical, even impossible: completely restricting fishing is not an option.

Coral reefs of the world. Far too many people live far too close to far too many of them, for instance in the Caribbean and the Western Pacific (oceanservice.noaa.com)

Coral reefs of the world. Far too many people live far too close to far too many of them, for instance in the Caribbean and the Western Pacific (oceanservice.noaa.com)

Now a new and remarkable study indicates that some limited management can go a long way. We don’t have detailed long-term data on coral reefs to guide us, but we do now have current and recent data on a lot of reefs. A team of coral reef biologists has assessed what is known about the current status and recent history of 832 coral reefs, ranging from the most damaged to the most pristine (only 20 of the 832 are considered to be pristine).

The team compared fish biomass on the reefs – finding 1000 kg or more per hectare on a pristine reef, less than half that amount on overfished reefs, and as low as 10% of that amount on the most overfished reefs.

These illustrations are from the Nature article assessing 832 coral reefs. You will need to go to the article to see the details. a and b: The fish biomass on fished reefs is a small fraction of what exists on unfished reefs (red, extremely overfished; green, unfished). c: The less the fish biomass, the longer the time to full recovery when fishing is completely restricted  - 50-60 years for the most damaged. d: With limited regulations in place, ecological complexity (functional return) gradually increases (nature.com),

These illustrations are from the Nature article assessing 832 coral reefs. You will need to go to the article to see the details. a and b: The fish biomass of fished reefs is a small fraction of what exists on unfished reefs (red, extremely overfished; green, unfished). c: The less the fish biomass, the longer the time to full recovery if fishing is completely restricted – 50-60 years for the most damaged. d: With limited regulations in place, ecological complexity (functional return) gradually increases (nature.com),

Unexpectedly, limited regulations can still have considerable impact. For instance, protecting herbivorous grazers, scrapers and browsers (Parrot Fish come to mind) reduces algal cover, promotes coral dominance once again, and raises fish biomass. Eliminating the most damaging fishing gear, like beach seines, also helps fish recovery. Restricting access to the reef to those with negotiated rights to fish there while excluding external fishers helps even more. Sustainable fishing becomes possible.

Parrotfish (this is the Bicolor Parrotfish) are critical herbivores on a coral reef, sraping back algae (ecology.com)

Parrotfish (this is the Bicolor Parrotfish) are critical herbivores on a coral reef, sraping back algae (ecology.com)

Currently most reefs anywhere near human communities are hardly managed at all. Now we know that with limited regulations, a reef can recover to about half of its pristine fish biomass, and when it does, it is much less likely to collapse.

So sustainable fishing on somewhat recovered coral reefs is a target we can realistically aim for, an outcome so very clearly worthwhile in itself. These are grounds for a little optimism.

Will such changes then also make the reefs more resilient to the stresses of rising ocean temperatures and acidification associated with climate change? Coral reef biologists predict that they will, but though the theory is sound, it is untested.

Let’s find out. It’s the least we can do.

What Coral Reefs Can Teach Us

Tuesday, September 30th, 2014

On many coral reefs, the living corals have died, the reef has turned to rubble, and diverse algae have overgrown the rubble. So far, about 80% of coral cover on Caribbean reefs has been lost, and about 50% has been lost on the reefs in the tropical Pacific. Ecologists call this shift in ecosystem structure a phase shift, or ‘regime change’.

This global coral reef disaster is not a new and sudden response to some new stress. The shift to algae has been coming for 3 or 4 decades, and the stresses responsible include overfishing of both predators and herbivores, pollution, demolition, hurricanes, diseases of both corals and sea urchins, along with ocean warming and coral bleaching. Sea level rise and ocean acidification pose ever greater threats in the decades ahead.

Surviving coral reefs around Indonesia are still fished illegally with dynamite (solcomhouse.com)

Surviving coral reefs around Indonesia are still fished illegally with dynamite (solcomhouse.com)

If we could stop the fishing, the pollution, and the habitat destruction, as we do in no-take Marine Protected Areas, and assuming for the moment that the ocean is not going to get too warm, too high, or too acidic too quickly, what kind of coral reef recovery is then possible?

If herbivores like parrot fish and sea urchins return to a reef, they can clear the algae off pieces of the substrate, and coral larvae have a chance to colonize. Whether they succeed depends on many factors: light, current, predators, competition, chance, and even the ‘taste’ of the reef. But recovery is at least possible.

To help coral reefs recovery, corals are grown for a year or two and then transplanted to a damaged reef (digitaljournal.com)

To help coral reefs recovery, corals are grown for a year or two and then transplanted to a damaged reef (digitaljournal.com)

Of course we cannot pretend that climate change will not devastate coral reefs, no matter how resilient they might be now. Even under ideal conditions, recovery would take decades, and time is something we don’t have much of.

But coral reefs may still have a lot to teach us. We know now that shifts from one stable phase to another stable phase of an ecosystem can take decades, and is likely to be the result of accumulating and interacting stresses. Such a shift may start without our recognizing it for decades, and once we finally recognize it, there may then be little we can do about it. As the climate warms, we are likely to see this play out repeatedly in both marine and terrestrial ecosystems.

Can it also occur at a planetary scale, shifting us from a cool and dry planet to a hothouse planet? It has happened before. Perhaps it has already started, a result of accumulating stresses that we have caused, passing a tipping point we have not noticed.

Or perhaps we have not reached that point, and we can recover some of what we have lost, like no-take zones in MPAs. Perhaps we can still slow the process enough so that the outcome is one we and most of our co-existing species can tolerate as we too explore the limits of our resilience.

Coral reefs as we remember them (plaza.ufl.edu)

Coral reefs as we remember them (plaza.ufl.edu)

The Great Barrier Reef : We Barely Knew You

Wednesday, August 6th, 2014

We are going to lose our coral reefs within the next century – including the greatest of them all, the Great Barrier Reef. Warming ocean temperatures, coral bleaching, and ocean acidification will kill them. This is without the overfishing, habitat destruction and pollution that already seriously stress them. Some very tolerant and adaptable coral species will probably persist, but the reefs will crumble.

The Great Barrier Reef extends for 1430 miles close to the coast of northeast Australia, with 3000 separate reefs or cays, and hundreds of islands (cairnsdiveadventures.com.au)

The Great Barrier Reef extends for 1430 miles close to the coast of northeast Australia, with 3000 separate reefs or cays, and hundreds of islands (cairnsdiveadventures.com.au)

Coral reef biologists continue to have depressing annual meetings. Individuals, scientists, NGOs and other organizations all continue to search for ways to protect reefs and give them more time to adapt to what lies ahead. But what lies ahead is bleak indeed.

What to do? Just accept it and watch it happen? Find some way to prevent it? Though much has been written about this, Ian McCalman’s new book The Reef is an intriguing contribution.

Historian Iain McCalman book The Reef takes us from Captain Cook's imperial invasion to the impact of current climate change,

Historian Iain McCalman book The Reef takes us from Captain Cook’s imperial invasion to the impact of current climate change,

It is, to start with, a very fine book. It tells the history of our emerging understanding of the Great Barrier Reef through the journals and accounts of 20 people, in 20 chapters, starting with Captain Cook’s trip up the GBR Inner Passage in 1770, one he was lucky to survive with his repaired ship still floating.

Captain Cook on his first trip mapped the coasts of New Zealand and Eastern Australia (gbrexperience.com)

Captain Cook on his first trip mapped the coasts of New Zealand and Eastern Australia (gbrexperience.com)

Then some of the naturalists on board subsequent navigating trips by other ships used the opportunity to get to know the Aborigines and the geology and some of the biology of the reef. The naturalists mainly counted species, all well known long before that by the coastal Aborigines.

Some castaways from ships wrecked on various parts of the reef at the north end near Torres Straight were saved and adopted by Aborigines, and lived to tell their remarkable stories about the people who were radically different from their popular reputation as savage, violent and ignorant cannibals.

And then in the early 1900s came the trained naturalists and scientists who began more serious study of the reef. Maurice Young’s year long expedition in 1929, leading a team of 14 scientists (amazingly for its time, 6 were women) revealed a lot about corals and their commensal and possibly symbiotic algae (known as zooxanthellae).

The colors of coral come from their symbiotic zooxanthellae that are expelled when ocean surface temperatures rise a couple of degrees, bleaching the corals (lovethesepics.com)

The colors of coral come from their symbiotic zooxanthellae that are expelled when ocean surface temperatures rise a couple of degrees, bleaching the corals (lovethesepics.com)

Yonge and the team wrote extensively about the year, drawing attention to the great uniqueness of the GBR – and unintentionally attracted hordes of tourists with all their collateral damage. So close to the mainland, the unprotected reef became stressed by resorts, pollution, uncontrolled fishing, destructive dynamiting, and growing interest by oil and gas companies.

All of this provoked the increasing concern of the conservationists and ecologists emerging over the past half century. In 1979, after great conflict among the players, the GBR Marine Park was finally created. In 1981 UNESCO designated it a World Heritage Site.

McCalman concludes the personal narratives with an account of the naturalist and coral expert, Charlie Veron, who early on recognized the growing threats to coral reefs from climate change. He published his own fine book in 2009 with the sobering title A Reef in Time: the GBR from Beginning to End.

Charlie Veron's book tells the history of the GBR and its imminent end (amazon.com)

Charlie Veron’s book tells the history of the GBR and its imminent end (amazon.com)

At the very end of his book, McCalman tries not to leave us in fatalistic despair about the reef by sharing the anecdotes of some very resilient humans, determined to not give up.

But that is not enough.

The only real hope for any kind of coral reef survival is rapid reduction of CO2 emissions. We need to dispel the myths that prevent the US, Canada and other nations from taking action. And we need to nourish plausible new ideas, like the cap-and-dividend proposal of US Congressman Chris Van Hollen which even libertarians seem to like.

But all of this has happened far too quickly. Just under three centuries will have passed from our ‘discovery’ of the GBR to its probable destruction at our hands.

We thought we would have more time together.

Live Reef Fish Food Trade

Monday, July 8th, 2013

If you live in Hong Kong or in cities such as Beijing and Shanghai, you can choose the fish you want to eat at a restaurant from a tank full of living, swimming fish. It will probably be a grouper, and it will be very expensive, perhaps $300 a plate, but it will be fresh, and it will taste good.

Groupers ("coral trout") at a restaurant in Shanghai (tracc-borneo.org)

Groupers (“coral trout”) at a restaurant in Shanghai (tracc-borneo.org)

Though the Live Reef Fish Food Trade started slowly in the 1970s, it has exploded in the past decade. It is causing extraordinary damage to coral reefs.

The target species are mostly groupers, snappers and wrasses. They are caught as adults and shipped to the restaurants, or they are caught as juveniles and kept in cages, fed small reef fish until they are plate sized, and then shipped to the restaurants.

They come from the Coral Triangle area, the region of the tropical Pacific with the greatest density of coral reefs. They are caught by hand, but usually after they are stunned by dynamite (illegal everywhere) or by cyanide poisoning (also illegal everywhere).

The Coral Triangle, including the reefs of the Philippines, Indonesia, Malaysia, PNG and Solomon Islands). (natureconservancy.org)

The Coral Triangle, including the reefs of the Philippines, Indonesia, Malaysia, PNG and Solomon Islands. (natureconservancy.org)

A masked diver applies cyanide to part of a reef in hopes of finding a few young groupers among the stunned fish (fishchannel.com)

A masked diver applies cyanide to part of a reef in hopes of finding a few young groupers among the stunned fish (fishchannel.com)

Another fisherman detonates dynamite to stun fish (turingfoundation.org)

Another fisherman detonates dynamite to stun fish (turingfoundation.org)

As reefs are stripped of the fish, the collectors go ever farther away – an expansion that has extended into the Indian Ocean and through the South Pacific.

Fish are collected from ever further sources as reefs are serially over-fished. (wwf.panda.org

Fish are collected from ever further sources as reefs are serially over-fished. (wwf.panda.org

Fishing has been ‘open access’, which essentially means few regulations, and where any exist, little enforcement exists. The catch is largely illegal, unregulated, and under-reported (the discouraging IUU designation).

Three countries provide most (but not all) of the fish – Indonesia, the Philippines and Malaysia. China (including Hong Kong) is the single major market and it continues to expand rapidly: a novel, good tasting, living grouper is a fine luxury meal in a newly affluent society.

Fish are shipped to Hong Kong, and then distributed to other cities in southern China (sciencedirect.com)

Fish are shipped to Hong Kong, and then distributed to other cities in southern China (sciencedirect.com)

Groupers are the main victims. They live for a few decades, they grow relatively slowly, they don’t mature until they are relatively large and 5-10 years old, they don’t swim fast making them easy for human divers to approach, and they spawn in aggregations in predictable places, making it even easier to find and catch them. Targeting juveniles and using destructive fishing techniques should have disappeared decades ago yet they are flourishing in the current hunt.

A tiger grouper, now listed by IUCN as threatened or endangered (bergoiata.org)

A tiger grouper, now listed by IUCN as threatened or endangered (bergoiata.org)

Territorial conflicts have arisen among all of the players – between local fishermen and outsiders, between local and state fishers and agencies, between communities and between states, between conservationists and the need for jobs. And as usual, despite the market value of the fish, the fishers/divers are paid little.

This is a classic boom-and-bust scenario. Given the lucrative and growing market in China, the ease of capturing the fish, the lack of both regulations and enforcement, a projected demand that far exceeds the projected supply, and inadequate knowledge of the biology of the species, groupers in the region are declining rapidly to extinction.

Certainly there are efforts to underway to protect the fish and regulate the fishing. In February 2013 government representatives of the six Coral Triangle nations met with those from a few SE Asian countries to address the threats and propose more effective management and sustainable trade in living reef fish. They proposed the development of marine protected areas to protect spawning aggregations, accreditation procedures for fishermen, and methods to detect cyanide in fish in order to prohibit its use. They addressed the issues of capture of juveniles for grow-out farms, and the capture of feed fish for the groupers that would otherwise be food for fish communities on the reefs. Worthwhile initiatives that may be too late.

Perhaps groupers are just unlucky, carrying the wrong suite of characteristics to survive unregulated human greed and predation. But that’s an inadequate conclusion. The ‘illusion of plenty’ has been dispelled in many parts of the world, and it needs to be dispelled in the Coral Triangle nations and communities. Governments and NGOs can do a lot to change perceptions and habits.

A goliath grouper, one of the largest species, easy to approach and photograph, easy to capture (thebuzzmedia.com)

A goliath grouper, one of the largest species, easy to approach and photograph, easy to capture (thebuzzmedia.com)

At the same time China is a huge and voracious market, perhaps insatiable. If a lack of eco-consciousness is also driving the desire for live reef fish in the restaurants, then it too can change.

But this is much more than just another sad example if boom-and-bust overfishing. Coral reefs are also under increasing stress from climate change, and the community disruption and damage resulting from the Live Reef Fish Food Trade will only increase their vulnerability.

The Live Reef Fish Food Trade is ethically wrong, environmentally catastrophic, and quite unnecessary. If all participants truly understood the impact it is having, surely they would agree to end it.

Failure to Protect The Great Barrier Reef

Monday, February 25th, 2013

Last summer UNESCO’s World Heritage Committee threatened to downgrade its listing of the Great Barrier Reef from World Heritage Area to Heritage Site in Danger. Downgrading the listing could repel tourists, and ought to be a blow to national pride.

The Great Barrier Reef, managed well since 1994, remains threatened by pollution, warming seas and now coal and natural gas facilities at its southern end (bayrun.com.au)

The Great Barrier Reef, managed well since 1994, remains threatened by pollution, warming seas and now coal and natural gas facilities at its southern end (bayrun.com.au)

The GBR has suffered stress from the usual suspects for decades – overfishing, mining, Crown-of-Thorns starfish plagues, run-off from adjacent mainland coastal farms. Now add to those the coral bleaching and intense cyclones of recent years associated with climate change, as well as the looming devastating impact of ocean acidification. Not surprisingly, half the coral cover has been lost or damaged since the 1980s.

Coral bleaching has killed and damaged corals on the GBR just as it has on reefs around the world (scienceonline.org)

Coral bleaching has killed and damaged corals on the GBR just as it has on reefs around the world (scienceonline.org)

The World Heritage Committee based its threat on the recent developments at Gladstone and nearby Curtis Island, at the southern end of the reef. Gladstone has become the largest center for coal export in Australia – there are huge seams of coal running north-south in the eastern part the country adjacent to the reef. The coal is sent where you would expect, to Japan, China, South Korea and India. Now the port of Gladstone is being dredged even deeper to handle ever more and larger ships.

The eastern part of Australia is rich in coal resources.

The eastern part of Australia is rich in coal resources (Haliburton.com).

That’s part of UNESCO’s concern.

The other part involves coal seam gas, gas that is or can be extracted during the coal mining process. Curtis Island, lying close to Gladstone, is actually part of the GBR World Heritage Area. However, it is now under extraordinary development to liquefy the coal seam gas to liquid natural gas (LNG), and send it off in refrigerated tankers to consuming nations where it will rendered back into natural gas. The liquid takes up 1/600th the volume of the gas, so the advantage of shipping it as liquid is obvious.

The World Heritage Committee report (p20-22) calls for these developments to cease and for a review of their impact. Since no actual sanctions by UNESCO are possible, beyond downgrading of the status of the Reef, what kind of response can we expect?

The Queensland Government has now submitted a defensive response, promising an independent review of the the Port of Gladstone, and commenting on existing water quality improvement programs, research initiatives, the GBR zoning plan, the Coral Sea reserve, and the recently implemented national carbon tax. The number of gas ports under development will be limited, but they will still be in the World Heritage Area.

However, as the Premier of Queensland said early on, ‘We are in the coal business’. That hasn’t changed.

So there will be no reconsideration, no precautionary plan, no delay in port or LNG development. The long-term threat to the reef is dismissed.

Is this anyway to treat a World Heritage Area? Liquid Natural Gas facilities under development on Curtis Island (Greenpeace.org)

Is this anyway to treat a World Heritage Area? Liquid Natural Gas facilities under development on Curtis Island (Greenpeace.org)

We shouldn’t be surprised. Extract and sell is the mantra of resource exploitation in Canada, the US, Africa, South America, Asia – and Australia. The exported coal and LNG from Gladstone and Curtis Island will no doubt support the Queensland economy, providing jobs and infrastructure. Unfortunately, given the other stresses that already exist, there isn’t any reason to think that a severely damaged GBR will be able to recover.

The tension between extracting resources and conserving natural ecosystems is familiar to us everywhere. You would think one place where conservation trumps extraction would be The Great Barrier Reef. Apparently not.

Will anyone listen to the outcry in defense of the Great Barrier Reef? If you would like to add your voice, visit: ‘Save the Reef’ It could only help.

So worth protecting

So worth protecting (ngm.nationalgeographic.com)

How Resilient Are Coral Reefs?

Thursday, August 2nd, 2012

On the Pacific coast of Panama, coral reefs exist in a fairly narrow band of tropics compressed between cold water currents that flow south along the California coast and north along the Peruvian coast. Not exactly the extensive coral reefs of the South Pacific, but still, they are there.

Sea surface temperatures in the tropical Pacific. That’s supposed to be Central America in the upper right, Indonesia in the lower left. Blue indicates cool water, red to yellow increasingly warm water. The ocean currents compress the tropics in the Eastern Pacific compared with the Western Pacific (pord.ussd.edu)

An elegant piece of research published last month in Science indicates that reefs may be resilient, able to cease growth during harsh times, and then regrow once conditions improve. The Pacific Panama reefs are about 7000 years old, but from 4000 years ago to about 1500 years ago, they quit growing. Then they started to grow again.

The 2500 years of no growth is correlated with a long period of intense El Nino and La Nina activity. If the greater stress of these events caused the reefs to stop growing, then the same should have occurred broadly around the tropical Pacific. This appears to be true.

How does a dormant or dying reef reef recover? In the case of the Panama reefs, it is very likely that as conditions improved, the reefs were recolonized from remnants of reefs that had survived in sites less affected by the stressful times.

Cauliflower coral, Pocillopora damicornis, dominates the coral community of the reefs off the west coast of Panama. According to cores made into several of the reefs, growth of this species ceased for 2500 years (loiczsouthasia.org)

A reasonable conclusion is that if we now just stopped – and reversed – the increase in CO2 emissions that our current coral reefs could recover.

But that’s the kicker, isn’t it? CO2 emissions continue to rise every year, and we have no reason to think they will stabilize, let alone reverse, in any political future we can see.

Earlier this summer, 2000 coral reef biologists got together for one of their regular international meetings. They produced a Consensus Statement that they are all signing, and it is a clear, concise and grim summary of the predicament that coral reefs face as ocean temperatures rise, ocean acidification continues, and other stresses of over-fishing and pollution continue relentlessly. The only hope for coral reefs is for CO2 emissions to be reduced.

This is part of the statement (and here’s the full statement)
“CO2 emissions at the current rate will warm sea surface temperatures by at least 2-3°C, raise sea-level by as much as 1.7 meters, reduce ocean pH from 8.1 to less than 7.9, and increase storm frequency and/or intensity. This combined change in temperature and ocean chemistry has not occurred since the last reef crisis 55 million years ago.”

Coral reefs will not survive what we doing to the planet.
As I and many others have written before, that is beyond sad. We have evolved in a complex, beautiful and who knows how unique world, and we are wrecking it.

Reefs at Risk

Saturday, February 26th, 2011

Cyclone Yasi, as big as Katrina, and one of the strongest cyclones in a century, swept across the Great Barrier Reef and on into Queensland on Feb 2. A coral reef has little defense against such a storm.

Crossing the unusually warm Coral Sea before it got to the reef, it grew in strength to Category 5 – just as Katrina grew to Category 5 when it blew across the warm Gulf of Mexico. The Coral Sea has in fact never been warmer, a product of the impact of the current La Nina and the long-term warming of the ocean.

Cyclone Yasi, Category 5, about to hit Queensland on Feb 2 (oz.climatesense.com)

Because of the warmer surface waters, this has been another bad year of global coral bleaching on reefs from the Indian Ocean, Thailand, the Maldives, and the Caribbean, probably as bad as 1998, certainly worse than 2002 or 2005. Global bleaching events such as these used to occur every hundred or a thousand years. No longer.

Coral bleaching occurs when water temperatures get too warm and symbiotic algae called zooxanthellae are expelled (csdpd.noaa.gov)

Corals live very close to their upper lethal temperature limits, and a rise in surface temperatures of just 1-2 degrees centigrade is enough to cause extensive coral bleaching. Following the global bleaching of 1998, about 15% of corals failed to recover. We’ll see soon enough how much recovery occurs from the global bleaching of this last year.

At the same time, as atmospheric carbon levels continue to rise, the oceans are becoming more acidic. This is the greatest threat of all: at some point calcareous skeletons of corals will no longer form and the reefs will crumble. Only a reduction in atmospheric levels of CO2 will prevent this, and we all know now how unlikely that is.

As atmospheric CO2 rises, so does the amount of CO2 dissolved in sea water, and the pH gradually drops, making sea water more acidic (ioc.ionesco.org)

Coral reef scientists around the globe have been warning us for some years that coral reefs are not going to survive global warming. The warnings have now escalated. The World Resources Institute, along with the Nature Conservancy and a diversity of coral reef monitoring organizations, has just published “Reefs at Risk Revisited”, updating its last report of 1998. Local and global stresses now threaten 75% of reefs. Without action on our part, by 2030 that will be 90%, and by 2050, all of them.

Of course, efforts to protect the reefs from overfishing, destructive fishing, pollution, and coastal development are all worthwhile, allowing the corals to be as resistant as possible to the serious global stresses of warming temperatures, coral bleaching, and ocean acidification. But there probably isn’t a single coral reef scientist left who thinks there will still be reefs in existence for our grandchildren to see.

What will the world look like without reefs? This isn’t hard to imagine – we need only go to many parts of the Caribbean and snorkel or dive around reefs that now are dead and crumbling rubble, covered with macroalgae.

A Caribbean coral reef reduced to rubble, abandoned by most fish and all scuba divers (coralreefresearch.org)

The costs are huge. A coral reef dies, and those who depend on it leave or die with it – reef fish and their prey and predators, scuba diving operations, recreational visitors, community fishermen, everything is lost. Vulnerable tropical countries, most of them island nations, are now advised to reduce their dependence on coral reefs, and ‘build adaptive capacity’.

We don’t know if life is abundant or rare in the universe, but we can make some reasonable guesses. With 100 billion galaxies, each with its trillion or so stars, life is probably not unusual. But it is probably bacteria-like rather than multicellular, for after all that’s what life on our own very benign planet looked like for a couple of billion years or more.

Stromatolites are mounds of cyanobacteria and look like rocks. They dominated life on Earth for about two billion years. Life on other planets may be no more complex. (fas.org)

Complex ecosystems like those we find on Earth may be extraordinarily unusual across the universe. And even if complex life has evolved elsewhere, it will be different, contingent on the interacting pressures and planetary events of their own systems. Coral reefs evolved here, on Earth, and probably nowhere else.

Other ecosystems may survive these perilous times through adaptation, resilience, and migration to different latitudes. But not coral reefs. We’ve become familiar, even comfortable, with the extinction of particular species. But the extinction of an ecosystem? That is something very different.

There are no words that I know of to express the depth of such a loss. It is a loss to our universe.

Great Barrier Reef. See it while it's still there. (rtdiveclub.com)