Soft corals are reef builders too!

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New research suggests that soft coral might be vital for the health of our oceans.

Scientists in Tel Aviv and Taiwan have found that, like stony corals, soft corals are an essential building block in all reefs.

Previously it had been thought that these corals were only minor contributors to coral reefs but a major study of reefs in the South China Sea has found that in fact massive parts of the reefs are formed by tiny parts of the soft coral called sclerites – less than 1mm in length - cemented together by calcium carbonate.

The study done by researchers at Tel Aviv University, the Academia Sinica, the National Museum of Natural Science of Taiwan, and National Taiwan University examined reefs in the Kenting National Park in South Taiwan.

Prior to this study it was thought that the soft coral was simply a kind of ‘veneer’ for the reefs with little or no value for the reefs. The work revealed that these soft coral are in actual fact essential for the reef ecosystem; providing homes for creatures such as fish, snails and algae as well as acting as natural wave breakers near to shore.

Professor Benayahu, one of the authors of the paper, cautioned thought that while soft coral is rich in biodiversity it is woefully understudied and in danger of being wiped out.

"As burning oil dissolves into the sea water, the water becomes more acidic, which then dissolves calcareous materials," he warns.

This includes corals whose skeletons are made of calcite. Prof Benayahu urges further studies on soft corals including the rate that they build reefs and their response to changes in temperature, water acidity and rising sea levels to make fully informed choices, without which some of the essential building blocks on which our oceans are founded may be lost.

For more information see: M.-S. Jeng, H.-D. Huang, C.-F. Dai, Y.-C. Hsiao, Y. Benayahu. Sclerite calcification and reef-building in the fleshy octocoral genus Sinularia (Octocorallia: Alcyonacea). Coral Reefs, 2011; DOI: 10.1007/s00338-011-0765-z

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