“One third of coral species face extinction”

The Telegraph, 10th July

One third of the major reef-building coral species are vulnerable to extinction, and the pace of destruction is increasing so it is conceivable that the "rainforests of the ocean" could be wiped out this century.

The warning that coral communities are faring even worse than their terrestrial counterparts, notably tropical rainforests, is given by an international team led by Prof Kent Carpenter, Director of the Global Marine Species Assessment Of Conservation International And The International Union For Conservation Of Nature, IUCN.

Built over millions of years, coral reefs are home to more than 25 percent of marine species, making them the most biologically diverse of marine ecosystems.

The loss of reefs could have huge economic effects on food security for around 500 million people who are dependent on reef fish for food and/or their livelihoods and tourism is also likely to suffer.

"The results of this study are very disconcerting," said Prof Carpenter, lead author of the Science article.

"When corals die off, so do the other plants and animals that depend on coral reefs for food and shelter, and this can lead to the collapse of entire ecosystems."

"Whether corals actually go extinct this century will depend on the continued severity of climate change, extent of other environmental disturbances, and the ability of corals to adapt," the article concludes.

"Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures."

Researchers identified the main threats to corals as climate change and local stresses resulting from destructive fishing, declining water quality from pollution, and the degradation of coastal habitats.

Climate change causes rising water temperatures and more intense solar radiation, which lead to coral bleaching and disease often resulting in mass coral mortality. Bleaching happens when the water temperature rises to the point where it kills the tiny polyps that make up the coral, leaving behind the white limestone skeleton of the reef.

With colleagues, Prof Carpenter has compiled data for over 700 coral species and classified their conservation status according to the IUCN "Red List" Categories and Criteria. Their analysis indicates that, of 704 species, 231 are in the "Critically Endangered," "Endangered," or "Vulnerable" categories.

The results also indicate the extinction risk of corals has increased over the past decade. Before the massive bleaching events of 1998, which wiped out around 16 per cent of reefs, only 13 species would have been included in the three threatened categories based on the data available today. The vast majority – 671 – would have been categorised as of "least concern."

The Caribbean has the largest proportion of corals in high extinction risk categories, with notable declines of staghorn and elkhorn corals, while the Coral Triangle (Indo-Malay-Philippine Archipelago, western Pacific) has the highest proportion of species in all categories of elevated extinction risk, notably as a result of warming.

Corals in oceanic islands of the Pacific generally have the lowest proportion of threatened species and Hawaiian reefs have been spared extensive coral loss from bleaching or disease. However, it hosts several rare species may prove especially vulnerable to future threats. Corals from the genera (group of species) Favia and Porites were found to be the least threatened due to their relatively higher resistance to bleaching and disease.

Marine researchers at the International Coral Research Symposium (ICRS) in Fort Lauderdale, Florida, this week are exploring the longer term consequences of widespread loss of corals due to global warming and ocean acidification.

Chair of the Climate Change session, Prof Ove Hoegh-Guldberg of the ARC Centre of Excellence for Coral Reef Studies and University of Queensland, said: "The evidence suggests reef systems are becoming more brittle, as a result of bleaching, disease and the effects of acidifying water – and this means we are likely to see more moonscape-like areas where reefs once used to be. This will be accompanied by a switch from the spectacularly colourful fish that people normally associate with reefs to much fewer and plainer ones."

"The loss of reefs will also expose coastal communities, already facing rising sea levels, to a greater risk from storm surges and tsunamis – as reefs currently provide a protective barrier against these," he said.

"This will be accompanied by murkier, less productive waters as water quality suffers." Researchers have found evidence that the rate at which coral reefs have been deteriorating and disappearing has accelerated in the last five years.

"For the past 30 years the loss has been between 1-2 per cent of the world’s coral per year," he said. "The latest data suggests the rate is now around 2 per cent a year. This doesn’t give us much time."

Emerging evidence indicates some corals have suffered a 20 per cent reduction in their growth rates, which researchers consider to be due to the rising acidification of sea water making it harder for them to build their chalky skeletons.

"This apparent drop in calcification is bound to be a real issue for discussion at the symposium," he said.

Most disturbing of all were recent claims by some atmospheric researchers that the level of carbon dioxide has been underestimated, and may be closer to 410 parts per million, than to the 385 estimated by the Intergovernmental Panel on Climate Change (IPCC).

"If we continue on the pathway that we are on right now, we get to levels where you are looking at the total loss of reef structures worldwide. Under those conditions you just don’t have corals – no corals, and you also lose 50% of the fish and other species that live in and around corals," he said.

"We either reduce our carbon dioxide emission now or many corals will be lost forever," says Julia Marton-Lefèvre, IUCN Director General.

"Improving water quality, global education and the adequate funding of local conservation practices also are essential to protect the foundation of beautiful and valuable coral reef ecosystems."

1 thought on ““One third of coral species face extinction”

  1. I have read some of the many news reports on the ocean acidification and reef crisis that are presently extant. I beg to differ with the position that reducing our global carbon footprint will help save our ocean bathing beauties, the reefs. It’s not that I don’t fully support reducing our carbon footprint, I am rather more concerned about the role of the present deadly dose of anthropogenic CO2 already in the air on its way to our surface ocean waters. Those hundreds of billions of tonnes of anthropogenic CO2, the bulk of which we’ve prescribed and put en route in the past 75 years, is slowly dissolving into the surface ocean. By most accounts CO2 in the atmosphere takes on the order of 200 years to equilibrate with the surface ocean. Hence the pH drop we’ve been recording is just the proverbial tip of the dry-iceberg.

    As the surface ocean absorbs the rest of this deadly dose, regardless of whether we emit more which we surely are doing, the acidification process already destined to occur is more than sufficient to change ocean ecology in far wider and disastrous fashion than merely scalding the bathing beauties at the shore. In fact the devastating effects CO2 has on the ocean is not proceeding only via H2O+CO2=H2CO3 (carbonic acid), there is a secondary reaction wherein CO2 is enhancing the greeness of the planets dry lands. There is is a major benefit our high and rising CO2 delivers to droughty grasses who are losing less water via evapotranspiration, remaining green and growing bushier each spring, and as such are superior ground cover thus reducing topsoil loss in the wind. Tragically that dust in the wind is the major source of vital mineral micronutrients for the open ocean. Prophetically it seems, all we really are is dust in the wind.

    So as our reef beauties cry out and dissolve like Dorothy’s wicked witch in our acidifying oceans, the acidification will certainly continue for at least another century unabated even if we never emit another molecule of fossil CO2 into the air. At the same time as the oceans suffer this chemical shock treatment, like those we give our swimming pools, they will continue as well to lose their photosynthetic capacity to counter this onslaught. The loss of net primary productivity, NPP, is reportedly 17% in the North Atlantic, 26% in the North Pacific, and 50% in the sub-tropical tropical oceans.

    We can find the fundamental proof of the depth of this problem by considering it from the point of view of basic chemical thermodynamics. Indeed we have expended a hundred terrawatts or so burning fossil carbon to put that deadly dose of CO2 into our atmosphere and ocean. No trivial energy savings will serve to counter its certain first principals chemical effects. We can still trust in what the Second Law of Thermodynamics teaches us in that one must balance equations energetically. If we are to address a problem created by terrawatts of energy we must devote terrawatts of energy. In this case those curative terrawatts better be emission free or we are lost.

    So where is there a source of emission free terrawatts of curative power we can devote to saving the oceans and help restore the balance of Nature? It is of course ONLY available from photosynthesis and therein lies the course we must chart to restore our oceans as we must surely not simply imagine the damage we’ve prescribed can simply be ignored and start from the present mortally wounded state. No mere conservation ethic or effort will suffice, we are far to far over the tipping point for that to work. We must replenish and restore ocean photosynthesis for there in the vast living ocean expanse the terrawatts of power, solar power, can be found and used to compete with the H2O+CO2=H2CO3 reaction. There in lies hope if we act now to assist the ocean plants, phyto-plankton, to convert CO2 in the ocean to life instead of death. Without replenished mineral micronutrients, without our determined efforts to administer the antidote, life in the oceans, and on this small blue planet, will surely revert to the cyanobacteroa; state from whence it came.

    If you are a religious person you might liken what we need to do as seeking absolution for our sins of emission by our acts of contrition and ecorestoration, otherwise the path to perdition is that of dissolution of those sins into dying oceans.

    Russ George – founder/president
    Planktos Science
    San Francisco

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