Community | September 21, 2010 | 35 comments

Extreme Heat Bleaches Coral, and Threat Is Seen

source: http://www.nytimes.com/2010/09/21/science/earth/21coral.htm?_r=1

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JanforGore
This year’s extreme heat is putting the world’s coral reefs under such severe stress that scientists fear widespread die-offs, endangering not only the richest ecosystems in the ocean but also fisheries that feed millions of people.

From Thailand to Texas, corals are reacting to the heat stress by bleaching, or shedding their color and going into survival mode. Many have already died, and more are expected to do so in coming months. Computer forecasts of water temperature suggest that corals in the Caribbean may undergo drastic bleaching in the next few weeks.

What is unfolding this year is only the second known global bleaching of coral reefs. Scientists are holding out hope that this year will not be as bad, over all, as 1998, the hottest year in the historical record, when an estimated 16 percent of the world’s shallow-water reefs died. But in some places, including Thailand, the situation is looking worse than in 1998.

Scientists say the trouble with the reefs is linked to climate change. For years they have warned that corals, highly sensitive to excess heat, would serve as an early indicator of the ecological distress on the planet caused by the buildup of greenhouse gases.

“I am significantly depressed by the whole situation,” said Clive Wilkinson, director of the Global Coral Reef Monitoring Network, an organization in Australia that is tracking this year’s disaster.

According to the National Oceanic and Atmospheric Administration, the first eight months of 2010 matched 1998 as the hottest January to August period on record. High ocean temperatures are taxing the organisms most sensitive to them, the shallow-water corals that create some of the world’s most vibrant and colorful seascapes.

Coral reefs occupy a tiny fraction of the ocean, but they harbor perhaps a quarter of all marine species, including a profusion of fish. Often called the rain forests of the sea, they are the foundation not only of important fishing industries but also of tourist economies worth billions.

Drastic die-offs of coral were seen for the first time in 1983 in the eastern Pacific and the Caribbean, during a large-scale weather event known as El Niño. During an El Niño, warm waters normally confined to the western Pacific flow to the east; 2010 is also an El Niño year.

Serious regional bleaching has occurred intermittently since the 1983 disaster. It is clear that natural weather variability plays a role in overheating the reefs, but scientists say it cannot, by itself, explain what has become a recurring phenomenon.

“It is a lot easier for oceans to heat up above the corals’ thresholds for bleaching when climate change is warming the baseline temperatures,” said C. Mark Eakin, who runs a program called Coral Reef Watch for the National Oceanic and Atmospheric Administration. “If you get an event like El Niño or you just get a hot summer, it’s going to be on top of the warmest temperatures we’ve ever seen.”

Coral reefs are made up of millions of tiny animals, called polyps, that form symbiotic relationships with algae. The polyps essentially act as farmers, supplying the algae with nutrients and a place to live. The algae in turn capture sunlight and carbon dioxide to make sugars that feed the coral polyps.

The captive algae give reefs their brilliant colors. Many reef fish sport fantastical colors and patterns themselves, as though dressing to match their surroundings.

Coral bleaching occurs when high heat and bright sunshine cause the metabolism of the algae to speed out of control, and they start creating toxins. The polyps essentially recoil. “The algae are spat out,” Dr. Wilkinson said.

The corals look white afterward, as though they have been bleached. If temperatures drop, the corals’ few remaining algae can reproduce and help the polyps recover. But corals are vulnerable to disease in their denuded condition, and if the heat stress continues, the corals starve to death.

Even on dead reefs, new coral polyps will often take hold, though the overall ecology of the reef may be permanently altered. The worst case is that a reef dies and never recovers.

In dozens of small island nations and on some coasts of Indonesia and the Philippines, people rely heavily on reef fish for food. When corals die, the fish are not immediately doomed, but if the coral polyps do not recover, the reef can eventually collapse, scientists say, leaving the fishery far less productive.

Research shows that is already happening in parts of the Caribbean, though people there are not as dependent on fishing as those living on Pacific islands.

It will be months before this year’s toll is known for sure. But scientists tracking the fate of corals say they have already seen widespread bleaching in Southeast Asia and the western Pacific, with corals in Thailand, parts of Indonesia and some smaller island nations being hit especially hard earlier this year.

snip

Parts of the northern Caribbean, including the United States Virgin Islands, saw incipient bleaching this summer, but the tropical storms and hurricanes moving through the Atlantic have cooled the water there and may have saved some corals. Farther south, though, temperatures are still remarkably high, putting many Caribbean reefs at risk.

Summer is only just beginning in the Southern Hemisphere, but water temperatures off Australia are also above normal, and some scientists are worried about the single most impressive reef on earth. The best hope now, Dr. Wilkinson said, is for mild tropical storms that would help to cool Australian waters.

“If we get a poor monsoon season,” he said, “I think we’re in for a serious bleaching on the Great Barrier Reef.”
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35 comments // Extreme Heat Bleaches Coral, and Threat Is Seen

  • IceKat
    • 0
      IceKat  

    • Unfortunately behind a paywall this paper named "Major bleaching events can lead to increased thermal tolerance in corals" contains the following passage.

      J. A. Maynard, K. R. N. Anthony, P. A. Marshall and I. Masiri

      Abstract.
      A key determinant of the fate of reef corals in a warming climate is their capacity to tolerate increasing thermal stress. Here, an increase in thermal tolerance is demonstrated for three major coral genera (Acropora, Pocillopora and Porites) following the extensive mass bleaching event that occurred on the Great Barrier Reef (Australia) in 1998. During the subsequent and more severe thermal stress event in 2002, bleaching severity was 30–100% lower than predicted from the relationship between severity and thermal stress in 1998, despite higher solar irradiances during the 2002 thermal event. Coral genera most susceptible to thermal stress (Pocillopora and Acropora) showed the greatest increase in tolerance. Although bleaching was severe in 1998, whole-colony mortality was low at most study sites. Therefore, observed increases in thermal tolerance cannot be explained by selective mortality alone, suggesting a capacity for acclimatization or adaptation.
      ____________________________________

      Who would have thought it, corals with the ability to acclimatize and adapt. It's not really surprising though, after all corals have been around for millions of years. Do people really think ocean temperatures have remained stable for all that time?

      Note the line, "despite higher solar irradiances during the 2002 thermal event" And you thought it was all about CO2!

    • 1 year ago
  • ayipis
    • -1
      ayipis  
    • Image

    • http://www.usatoday.com/life/movies/news/2010-09-22-waitingforsuperman22_CV_N.ht...

      These days, documentary films crowd theaters and TV screens, entertaining and illuminating, scooping up awards and respectable box-office receipts, and making a handful of filmmakers rich and famous. But do their films have an impact on whatever they're documenting?
      So far, the answer is: It's not always clear and rarely quantifiable.

      *****************
      someone from the past made a documentary..and sold the idea that the globe is getting warmer..to a bunch of americans neck deep in snow..

      and that man is now very powerful and very rich................VERY RICH .

    • 1 year ago
  • EthicalVegan
  • ayipis
    • -2
      ayipis  
    • Image

    • http://latimesblogs.latimes.com/lanow/2010/09/las-summer-ends-with-a-chill-it-wa...

      Southern California's summer to end with a chill: It was the coldest in decades

      Farewell summer, we hardly knew ye!

      The last day of summer is Wednesday, but meteorologists say the season barely bothered to show up in the region this year. So cooler fall will make an almost noiseless entrance Thursday, hardly indistinguishable from the summer Southern Californians just experienced.

      “Summer played hooky on us. It never really showed up,” said Bill Patzert, a climatologist for the Jet Propulsion Laboratory in La Canada Flintridge. “We leaped from spring to fall.”

      ***********************************

      BTW..its now called "climate disruption"....soon enough you guys would spin this shit so much it would be called.."global cooling"...

      keep them stoned and keep them stupid folks..

    • 1 year ago
  • IceKat
  • Gravity_Man
    • 0
      Gravity_Man  

    • I wonder why all the oil goop failed to protect the corals from getting too much sunlight? Perhaps the plankton that was shading the corals died. Ditto all the dead fish not casting a shadow.

    • 1 year ago
  • DrewLewis
  • EthicalVegan
  • JanforGore
    • +2
      JanforGore  

    • http://www.chemistrydaily.com/chemistry/Coral_bleaching

      Coral bleaching results when the symbiotic zooxanthellae (single celled algae) are expelled from the host coral organism due to stress. The corals that form the structure of the great reef ecosystems of tropical seas depend on these symbiotic photosynthesizing unicellular algae called 'zooxanthellae' that live within their tissues. When the zooxantheallae are expelled, the coral looses its pigment, leading to a bleached or completely white appearance.

      Coral bleaching is a vivid symptom of the stresses already being caused by global warming, but coral may be stressed by factors other than elevated sea surface temperatures, such as solar irradiance (photosyntheticaly active radiation and ultraviolet band light). Other anthropogenic factors include pollution and smothering silt runoff from coastal development. Stressors expose coral to diseases like white band disease and black band disease .

      If the stressors leading to the coral bleaching subside quickly, the coral host can repopulate its symbiotic algae within weeks or months.

      Other reef creatures have symbiotic zooxanthellae, which they may also expel under stressful conditions. Bleaching stress is also exhibited by soft corals, giant Tridacna clams and some sponges.

      The Great Barrier Reef along the northeast coast of Australia suffered two mass coral bleaching events in the summers of 1998 and 2002. While most reef areas recovered with relatively low levels of coral death, some locations suffered severe damage, with up to 90% of corals killed.

      Other coral reef provinces have been permanently damaged by warm sea temperatures, most severely in the Indian Ocean. Up to 90% of coral cover has been lost in the Maldives, Sri Lanka, Kenya and Tanzania and in the Seychelles.
      _______
      "If the stressors leading to the coral bleaching subside quickly"
      __
      This is not the case however regarding the overabundance of CO2 contributing to sea temperature increases as we continue to pump out millions of tons of CO2 daily through burning fossil fuels, deforestation, agriculture and the destruction of wetlands and peatlands which are CO2 sinks. Thirty percent of the world's coral reefs have now died. This is now why we must put forward a plan to decrease the CO2 emissions contributing to ocean temperature increases which are making our oceans more acidic. We can achieve this through renewable energy sources, sustainable agriculture, reforestation, and the preservation of peatlands and wetlands that store CO2, as well as addressing destruction of coral reefs through overdevelopment and tourism.

    • 1 year ago
  • JanforGore
  • ayipis
  • NaranjaCabeza
  • JanforGore
    • +1
      JanforGore  
    • Image

    • http://www.skepticalscience.com/Ocean-cooling-skeptic-arguments-drowned-by-data....

      Ocean cooling: skeptic arguments drowned by data

      In 2008, climate change sceptic Roger Pielke Sr said this: “Global warming, as diagnosed by upper ocean heat content has not been occurring since 2004”.

      It is a fine example of denialist spin, making several extraordinary leaps:

      •that one symptom is indicative of the state of an entire malaise (e.g. not being short of breath one day means your lung cancer is cured).
      •that one can claim significance about a four year period when it’s too short to draw any kind of conclusion
      •that global warming has not been occurring on the basis of ocean temperatures alone

      So much for the hype. What does the science say about the temperature of the oceans – which, after all, constitute about 70% of the Earth’s surface? The oceans store approximately 80% of all the energy in the Earth’s climate, so ocean temperatures are a key indicator for global warming.

      No straight lines

      Claims that the ocean has been cooling are correct. Claims that global warming has stopped are not. It is an illogical position: the climate is subject to a lot of natural variability, so the premise that changes should be ‘monotonic’ – temperatures rising in straight lines – ignores the fact that nature doesn’t work like that. This is why scientists normally discuss trends – 30 years or more – so that short term fluctuations can be seen as part of a greater pattern. (Other well-known cyclic phenomena like El Nino and La Nina play a part in these complex interactions).

      Looking at the trend in ocean heat, this is what we find:

      There are, however, disputes about the accuracy of Argo buoys and expendable measuring devices dropped into the sea, and the reporting of temperatures down to only 700 metres. How do scientists resolve these kind of disputes – bearing in mind that such disputes are the very stuff of science, the essence of true scepticism? One way is to find more data sources – different ways of measuring the phenomenon in dispute. By using results from seven different teams of scientists, all using different tools and methods, we are able to see a clear trend. And while there is variation between team results due to the differences in technique and measurement methods, one thing they all agree on: long term, temperatures are going up.

      he reaction of the oceans to climate change are some of the most profound across the entire environment, including disruption of the ocean food chain through chemical changes caused by CO2, the ability of the sea to absorb CO2 being limited by temperature increases, (and the potential to expel sequestered CO2 back into the atmosphere as the water gets hotter), sea-level rise due to thermal expansion, and the amount of water vapour in the atmosphere.

      While there is a great deal we don’t know about how the oceans behave, we do however know that it’s safer to discuss all aspects of climate change using multiple sets of data, rather than just one, as Pielke Sr did. If ocean heat is a guide, then global warming is still on track to cause great disruption if we don’t modify our actions to reduce the release of anthropogenic CO2.

      Claims that global warming is not happening on the basis of short-term ocean temperatures are not supported by the evidence.

    • 1 year ago
  • ayipis
    • -3
      ayipis  
    • JanforGore:

      "Claims that global warming is not happening on the basis of short-term ocean temperatures are not supported by the evidence."

      its not called global warming anymore...they will let you know as soon as they figure it out what it is and what to call it

      .till them go ahead and milk the public..there is money to be made out there..LOL

    • 1 year ago
  • themotivateddropout
  • EmperorThan
  • crystalman
  • ayipis
    • -4
      ayipis  

    • FYI..its no longer called "climate change" its officially....CLIMATE DISRUPTION..

      if you guys cant even figure out what to call it,how can i even trust that you guys even know what the 'eff' your doing..

    • 1 year ago
  • pandaman2105
  • IceKat
    • 0
      IceKat  
    • Image

    • "They are saying bleaching is the end of the world, but when you look into it, that is a highly dubious proposition." Peter Ridd, a physicist with Townsville's James Cook University.

      While GISS predict ocean temperatures to rise the fact is (according to The National Oceanographic Data Center) that oceanic heat content has been falling for the past five years. So, that's something to take into consideration when making predictions as to the state of future bleaching.
      Bleaching is nothing new, this quote from science.org.au
      "Coral bleaching is a natural process. For thousands of years, fishermen have noticed mysterious whitening of the reefs." although it goes on to state that bleaching has become more common in recent years. But isn't this to be expected seeing as the planet did warm slightly towards the end of the last century? As the planet once again cools, and as ocean temperatures continue to fall, this is surely good news for corals worldwide.

      But we've heard it all before. Professor Ove Hoegh-Gulberg, one of the chief alarmists, produced a paper stating that global warming would mean that bleaching events like the one that occurred in 1998 would happen every two years from 2010 and every year from 2020. As I've already pointed out, global ocean temperatures are now falling. Of course some people want to see a cooler earth, but they should take a look at how well corals do in cooler water before they wish for that.
      Not in the text above but stated in the original text is this sentence, "Temperatures have since cooled in the western Pacific and the immediate crisis has passed there..."

      The article also states "with corals in Thailand, parts of Indonesia and some smaller island nations being hit especially hard earlier this year" but then goes on to state "In Thailand, “there some signs of recovery in places,” said James True" so maybe it isn't all as bad as some people like to portray.

      So, coral bleaching goes on, as it always has done, but with reducing temperatures, and the coral's ability to survive and thrive after bleaching events, maybe this isn't as bad as it first appears.

    • 1 year ago
  • EthicalVegan
  • themotivateddropout
    • +3
      themotivateddropout  
    • EthicalVegan:

      Because of conspiracy theory conspiracy theorists.
      Convoluted, eh?
      These are people who turn any warning from a perceived liberal/democrat/environmentalist/hippie/stoner/gay/atheist into some wacky dishonest theory meant to somehow destroy everything America represents.

      People still laugh when I bring up global warming.
      Eventually that joke is gonna be considered black humor.

    • 1 year ago
  • EthicalVegan
  • ayipis
  • ayipis
  • themotivateddropout
  • themotivateddropout
  • themotivateddropout
    • +2
      themotivateddropout  
    • ayipis:

      Global warming has been a punch line around conservative waterholes for almost a decade. I've heard liberals and environmentalists literally begging people to believe that their neglect of the Earth will have negative long term repercussions.
      How about you search for Global Warming on the Current search bar.
      or Google it.

      Oh and by the way, I said perceived liberal/democrat/etc/etc...
      That means that's not always what they are, but what they are interpreted to be.

    • 1 year ago
  • EthicalVegan
    • +3
      EthicalVegan  
    • themotivateddropout:

      Oh, definitely at the disheartening situation.

      I so much enjoy your comments, I really do. Make that "appreciate" your comments. Thank you -- always -- for being able to write what I am capable only of thinking, but not putting down on paper the way you can.

    • 1 year ago
  • themotivateddropout
  • JanforGore
  • ayipis
  • fun_size
    • +2
      fun_size  

    • Sadly most people will gladly ignore this knowledge supposing themselves safe in their own ignorance. The world's oceans are far more delicate than people seem to think and yet we still continue to over fish and pollute the oceans indiscriminately. I fear for our future...

    • 1 year ago
  • JanforGore
    • +3
      JanforGore  
    • fun_size:

      Yes, it's that arrogance that we can do anything and it won't matter because the Earth is just too big to feel the effects of man's destructive behavior. As we can see, that is not true.

    • 1 year ago
  • JanforGore
    • +2
      JanforGore  

    • 'Scientists say the trouble with the reefs is linked to climate change. For years they have warned that corals, highly sensitive to excess heat, would serve as an early indicator of the ecological distress on the planet caused by the buildup of greenhouse gases.'

      Remember these quotes so you can tell your grandchildren when they ask if we knew this was coming and why we didn't do anything about it.

    • 1 year ago
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