Corals: More Resilient Than Many Have Thought

The review found that many studies had used flawed methods, subjecting marine creatures to sudden increases in carbon dioxide that would never be experienced in real life. ² In some cases it was levels far beyond what would ever be reached even if we burnt every molecule of carbon on the planet, said Howard Browman, the editor of ICES Journal of Marine Science, who oversaw the review. He said that a handful of influential scientific journals and lobbying by international organizations had turned ocean acidification into a major issue. ¹ Some recent studies:

• Lucy Georgiou and colleagues concluded that at least some coral has the ability to regulate its own internal pH. This allows the coral to thrive, even in extreme acid environments. ³
• The tropical, turquoise waters of the Palau Rock Island in the far western Pacific Ocean are naturally more acidic due to a combination of biological activity and the long residence time of sea water within its maze of lagoons and inlets. Sea water pH within the Rock Island lagoons is as low now as the open ocean is projected to be as a result of ocean acidification near the end of this century. ⁴ A study by scientists at Woods Hole Oceanographic Institution (WHOI) found that the coral reefs there seem to be defying the odds, showing none of the predicted responses to low pH except for an increase in bioerosion—the physical breakdown of coral skeletons by boring organisms such as mollusks and worms. ⁵ “Based on lab experiments and studies of other naturally low pH reef systems, this is opposite of what we expected,” says lead author Hannah Barkley. Surprisingly, in Palau where the pH is lowest, researchers saw a coral community that hosts more species and has greater coral cover than in the sites where pH was normal.
• Researchers from Northeastern University's Marine Science Center and the University of North Carolina at Chapel Hill have found that moderate ocean acidification and warming can actually enhance the growth rate of one reef-building coral species. Only under extreme acidification and thermal conditions did calcification decline. This work is the first to show that some corals may benefit from moderate ocean acidification. ⁶

Great Barrier Reef

The there's the question asking how much of the Great Barrier Reef has been destroyed. One of a number of reports says that 93% of the reef has been hit by coral bleaching.⁷ Joanne Nova says this is bunk. She reports, “Local dive operators (who possibly know what the reef looks like) found about 5% damage and describe the difference as phenomenal. Indeed, they say the reef is pretty much just like it was 20 years ago when they last did a survey.” They said, “The discrepancy is phenomenal. It is so wrong. Everywhere we have been we have found healthy reefs.” ⁸

Caribbean Reefs

Half of all coral species in the Caribbean went extinct between 1 and 2 million years ago, probably due to drastic environmental changes. Scientists working at the Smithsonian Tropical Research Institute (STRI) think one group of survivors, corals in the genus Orbicella, will continue to adapt to future climate changes because of their high genetic diversity. ⁹ In present times, the main reason why the area covered by live coral has more than halved since the 1970s are overfishing and coastal pollution, according to scientist Carl Gustaf Lundin. Dr. Lundin helped oversee an analysis by 90 experts of 35,000 surveys of Caribbean reefs over the past 40 years. Their report concluded that climate change had been wrongly blamed for a problem that had largely been caused by local factors which could have been controlled by better regulation.¹⁰

Warmer Water

Ocean warming, caused by man-made global warming, was supposed to lead to the destruction of the corals we've been told again and again, notes Pierre Gosselin. ¹¹ Yet, some folks are showing otherwise. Stanford researchers have shown that some corals can—on the fly—adjust their internal functions to tolerate hot water 50 times faster than they would adapt through evolutionary change alone.¹²) These findings make clear that some corals can stave off effects of ocean warming through a double- decker combination of adaptation based on genetic makeup and physiological adjustment to local conditions. Another study adds to the finding that corals are far more resilient than first thought. Hume and colleagues report that a number of coral species survive at sea water temperatures far higher than estimates for the tropics during the next century. They conclude, “We associate coral reefs with tropical seas of around 28 degrees so in that mindset even slight warming can have devastating effects on corals. But in the Arabian/Persian Gulf, corals can survive sea water temperatures of up to 36 degrees Celsius every summer, heat levels that would kill corals elsewhere. Corals have adapted.” ¹³

More on Adaptability

In one study adult corals were exposed to increased temperature and acidification. Then their offspring were exposed to the same conditions to see if trey were more successful because of their parent's experience. ¹⁴ Results revealed there was a more positive metabolic response and ecological response, greater survivorship and growth if the parents had been preconditioned to future scenarios, or as Joanne Nova notes, evolved to survive past ones. ¹⁵)

New Reefs Discovered

Until recently no one even knew that corals could grow just out from the river mouth of the Amazon. Then 9,300 square kilometers of reef was found living in a region no one thought corals could grow. This has astonished scientists, governments and oil companies who have started to explore on top of it. ¹⁶ The reef appears to be thriving below the freshwater plume or outflow. Compared to many other reefs, scientists say it is relatively 'impoverished.' Nevertheless, they found over 60 species of sponges, 73 species of fish, spiny lobsters, stars and much other reef life. ¹⁷ Joanne Nova observes, “The corals discovered near the Amazon might be quite important. The zone has been described as having a 'unique pH' which is a funny way to say that it was almost certainly a lower pH (because rivers are naturally low). Why hide that? It might show that corals aren't under as much threat from 'acidification' as some people want you do think.” ¹⁸ Researchers found another large reef system off Queensland, hidden under 20 m of water. Scientists found fields of strange donut -shaped mounds. The mounds are geological structures formed by the growth of a green algae made of living calcified segments. ¹⁹ So far, researchers have mapped more than 6,000 square kilometers, more than three times the previously estimated size of the reef. ²⁰ Says one researcher, “You're looking at these sites on a map going, maybe there's something there, then you dive over the side to have a look and all of a sudden are greeted with these coral habitats that you totally didn't expect.” ²¹

Sunscreen Contamination

As mentioned earlier when discussing Caribbean Reefs, heavy coral loss has been due to coastal pollution. Another pollution item posting a threat is sunscreen. New research finds that a common chemical in sunscreen lotions and other cosmetic products poses an existential threat—even in miniscule concentrations—to the planet's coral and coral reefs. The chemical oxybenzone (benzophenone-3) is found in more than 3,500 sunscreen products worldwide. It pollutes coral reefs via swimmers who wear sunscreen or waste water discharges from municipal sewage outfalls and coastal septic systems. ²² Oxybenzone pollution predominantly occurs in swimming areas, but it is also on reefs 5 to 20 miles from the coastline as a result of submarine freshwater seeps that can be contaminated with sewage. The chemical is highly toxic to juvenile corals. The lowest concentration to see a toxicity effect was 62 parts per trillion—equivalent to a drop of water in six and a half Olympic sized swimming pools. Researchers found concentrations of oxybenzone in the US Virgin Islands to be 23 times higher than the minimum considered toxic to corals. Oxybenzone was also found in high concentrations in the waters around the more popular coral reefs in Hawaii and the Caribbean. ²² References

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