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Climate change may kill off the worlds reefs within just a few decades predicts the latest International Programme on the State of the Ocean. Ove oegh-­‐Guldberg, Prof and Dir, Global Change Institute,University of Queensland, prepared the preliminary Case Study 2 which was a collaborative effort of 2 workshops dealing with ocean stress. These were the
International Earth System Expert Workshop on Ocean Stresses and Impacts held on the, 11th–13th April, 2011 and the International Earth System Expert Workshop on Integrated Solutions for Synergistic Ocean Stresses and Impacts, 2nd–4th April, 2012.

The preliminary report reiterated that coral reefs are the most diverse on the planet. And that the reefs are not only beautiful and provide food for millions, they also are coastal barriers to wave stress, protecting humans and infrastructure.

Coral reefs around the world are facing major stress from local factors such as overfishing, pollution, and unsustainable practices along tropical coastlines. Over the past 50 years, these activities have resulted in at least 40% of the world's coral reefs
disappearing. This problem is in itself extremely serious. Recently, however, climate change has also begun to threaten the world's reefs, through the dual effects of ocean warming and acidification.
Scientific projections of how the temperature and chemistry of the world's oceans will change in the future indicate a high risk of major catastrophe. Higher sea temperatures
and altered chemistries of the future are hostile to coral reefs, and are likely to eliminate
these wonderful ecosystems in the next 30-­‐50 years if urgent action is not taken.

Marine Pollution Bulletin (pdf) illustrates how our coral reefs will die as a result of climate change as well as other assaults.

Interactive effects among the main climate change factors of warming and ocean acidification and coral diseases.

Warming Induces coral bleaching; bleached corals are more sensitive to diseases and have lowered calcification rates; affects postdisturbance recovery through negative impacts on reproduction, development and recruitment

Warming's extreme temperatures will reduce calcification; Induces coral disease; disease stressed corals are more sensitive to bleaching and have reduced calcification rates; affects postdisturbance recovery through negative impacts on reproduction, development and recruitment and expending of resources to combat infection.

Ocean acidification and reduced carbonate and aragonite concentration. Results in reduced calcification; corals with reduced calcification are more sensitive to bleaching and diseases; affects post disturbance recovery through negative impacts on reproduction, development and recruitment

Ocean acidification and reduced carbonate and aragonite concentration. Results in dissolution of aragonite and calcite skeleton; weakened skeleton is more sensitive to the impact of bioeroders and storms.

Interactive effects of local stress factors on climate change factors and marine diseases.

Coral bleaching:

Sedimentation and turbidity increase coral susceptibility to
bleaching; decrease post bleaching recovery by smothering corals and limiting settlement of coral larvae.

Nutrients: increase coral susceptibility to bleaching through imbalance of nutrients in surrounding water that induces biochemical changes in cells; decreases post bleaching recovery through reduced reproductive output and by promoting growth of competitive algae, coral disease and increase of bioerosion and breakage

Overfishing: resistance to bleaching may decrease due to reduction in biomass and functional diversity in reef fishes; post bleachingrecovery by promoting overdominance of fleshy macroalgae and soft-bodied reef invertebrates, and loss of hard substrates due to intensified bioerosion and expansion of ‘urchin barrens’ associated with loss of keystone predators.

Destructive practices: physical destruction may result in partial
mortality and weakening, increasing susceptibility to bleaching; reduces post bleaching recovery through reduced reproductive potential, development and recruit survival

Coral Disease::

Sedimentation and turbidity: increase coral susceptibility to diseases; promote growth of disease causing micro-organisms and disease inducing fleshy macroalgae

Nutrients: induce proliferation of disease causing microorganisms and bioeroders; intensify growth of fleshy macroalgae that induce
coral diseases

Overfishing: reduction of keystone predatory fishes promotes population explosion of prey organisms that become vulnerable to marine diseases; reduction of herbivorous organisms promotes overgrowth of fleshy macroalgae that induce coral diseases

Destructive practices: corals suffering from mechanical damage are more sensitive to diseases; damaged corals may have low capacity of post disturbance recovery due to reduced reproductive potential as a result of trade-off between recovery and reproduction.

The Marine Pollution Bulletin concludes it's research with the following.

There is no single ‘most important’ stressor affecting coral reefs in the immediate term, rather different factors assume dominance in different areas and times. Continuing over-use or abuse of reef systems has already led to the demise of an unacceptably high proportion of reefs in all ocean basins, and reduction of many of the local stressors in most reef areas is clearly urgently needed. While it is common to refer to a certain percentage of the world’s or region’s reefs having suffered ‘degradation’ or similar, such statements  common in policy documents for example, appear to gloss over the fact that many reefs are already dead and probably an irrecoverable state. Thus, comments like a certain region has suffered a 30% decline in reefs’ may mean that 30% are dead and  irrecoverable, not that conditions on all of them have declined by  30%. The difference is critical. While CO2 rise is over-arching, it may be of little consequence to one of the approximately 25% of reefs that are already dead from other factors, the reefs having failed to ‘adapt’ to the stressors existing at those particular sites. Without coordinated action at local, regional and global levels to reduce local stress factors and combat climate change, there will be continued decline of reefs, and of their ability to support human communities. Present rates of deterioration, if continued, mean that most reefs will be lost as effective systems in a few decades. However, even if the local stressors can be averted, reduction of CO2 levels remains of paramount importance for their long term  survival. The current global targets of carbon emission reductions, including the targeted limit of a 2 C rise (450 ppm), are unrealistic and definitely not enough for coral reefs to survive, and lower targets should be pursued. Without such action then entirely new and radical conservation strategies may be required to protect remaining coral reefs (e.g. Rau et al., 2012), although in such a scenario survival of these ecosystems is likely to be confined to a few intensively- managed localities. A huge loss in biodiversity, and productivity which is of value to people, is inevitable in such a high CO2  world

Originally posted to Pakalolo on Fri Jan 03, 2014 at 01:48 PM PST.

Also republished by Climate Change SOS.

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Comment Preferences

  •  Tip Jar (15+ / 0-)

    "If you do not change direction, you may end up where you are heading."- Lao-Tzu

    by Pakalolo on Fri Jan 03, 2014 at 01:48:55 PM PST

  •  And in other depressing news: (4+ / 0-)

    From the Arctic to the equator and on to the Antarctic, jellyfish plagues (or blooms, as they’re technically known) are on the increase. Even sober scientists are now talking of the jellification of the oceans. And the term is more than a mere turn of phrase. Off southern Africa, jellyfish have become so abundant that they have formed a sort of curtain of death, “a stingy-slimy killing field,” as Gershwin puts it, that covers over 30,000 square miles. The curtain is formed of jelly extruded by the creatures, and it includes stinging cells. The region once supported a fabulously rich fishery yielding a million tons annually of fish, mainly anchovies. In 2006 the total fish biomass was estimated at just 3.9 million tons, while the jellyfish biomass was 13 million tons. So great is their density that jellyfish are now blocking vacuum pumps used by local diamond miners to suck up sediments from the sea floor.

    If Hobby Lobby is against contraception, why does it buy its inventory from China, the country that limits the number of children by law?

    by Inland on Fri Jan 03, 2014 at 02:33:19 PM PST

  •  since we neither eat coral (1+ / 0-)
    Recommended by:

    nor make petroleum products out of it, I can't imagine many of us will care. :-(

    Dogs from the street can have all the desirable qualities that one could want from pet dogs. Most adopted stray dogs are usually humble and exceptionally faithful to their owners as if they are grateful for this kindness. -- H.M. Bhumibol Adulyadej

    by corvo on Fri Jan 03, 2014 at 03:18:43 PM PST

  •  I snorkeled some coral that was badly damaged (1+ / 0-)
    Recommended by:

    by Super Typhoon Yolanda recently, near Coron Island in the Philippines. Sad to see coarl gardens turned into coral clear cuts.  

    "If Wall Street paid a tax on every “game” they run, we would get enough revenue to run the government on." ~ Will Rogers

    by Lefty Coaster on Fri Jan 03, 2014 at 06:00:41 PM PST

  •  Thank you for posting this diary. (1+ / 0-)
    Recommended by:

    Grim news, but necessary to the public.

    Poverty is not an accident. Like slavery and apartheid, it is man-made and can be removed by the actions of human beings. —Nelson Mandela

    by kaliope on Sat Jan 04, 2014 at 01:51:36 AM PST

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