Global warming is melting soft corals
November 13, 2007
Unlike conventional corals, soft corals have no calcified outer skeleton to protect and support them. When they die, they leave no trace of their existence. Benayahu has witnessed a sharp decline in soft corals in recent years. Whereas he once found soft corals in 50-60 percent of his study sites around the world, just a few years later only about five percent have soft corals.
"There was a massive disappearance of soft corals," he remarked about a Japanese soft coral reef. "You can't imagine this was the same site. Just two years passed and the entire area was deserted, lifeless."
A soft-bodied stony coral after exposure to acidified experimental conditions. Under relatively high temperatures, these corals may lose their algal symbionts and become pale (bleached) or even transparent. [Image courtesy of A. Briestien]
Anemone-like stony coral after exposure to acidified experimental conditions. While the soft body coral survives, reproduces and grows bigger than usual, it loses its calcareous skeleton. [Image courtesy of A. Briestien]
"It's too late. We have now actually missed the boat in finding some key pharmaceuticals," said Benayahu." There is a huge gap in our knowledge of soft corals in the reef environment, and with the rate of extinction, we have lost certain species forever."
While Benayahu warnings are dire, other research suggests that some types of corals may survive environmental changes caused by higher ocean acidity driven by elevated CO2 levels.
In March, Israeli biologists Maoz Fine and Dan Tchernov reported that some stony corals can survive increased acidity by morphing into soft-bodied polyp forms. The corals produce hard skeletons again once pH level returns to normal. The research helps explain when some corals disappear and reappear on the fossil record. As soft-bodied polyps, corals will not leave recognizable fossil remains.
Despite these findings, Fine and Tchernov warn that decreasing ocean pH will cause profound changes to most coral species, degrading overall coral reef health and the systems the ecosystems afford mankind.
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Coral reefs decimated by 2050, Great Barrier Reef's coral 95% dead
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