Soft Corals can Resist Harmful Effects of Decreasing Oceanic pH

Soft corals are more resilient to changes in oceanic acidity than previously believed, a new study has found.

Coral reefs provide shelter to thousands of marine organisms. Rising levels of carbon dioxide and ocean temperature are threatening the existence of these beautiful "forests of oceans."

A new study from Tel Aviv University researchers and colleagues has shown that soft corals can resist the harmful effects of decreasing pH in the ocean.

The research is published in the journal PLOS One.

"The rise in temperature and ocean acidification are the main concerns of environmental change," said Prof. Yehuda Benayahu from Tel Aviv University's Department of Zoology.

Oceanic acidification is caused by increased carbon dioxide emissions and pollution. The emissions dissolve in ocean water and decrease the pH of the water. A change in organic acidity of the ocean can disrupt lives of several marine creatures.

High levels of acidity, slows down calcification of stony corals, which is the leading cause for disappearance of coral reefs.

Researchers in the current study wanted to know whether soft corals can live in warmer, more acidic oceans of the future.

"I was curious as to whether coral tissue could protect the inner coral skeleton, which is of most use in terms of reef construction, so I conducted an experiment using live soft corals and soft coral skeletons, which were placed in tanks containing ocean water with manipulated pH levels," said Yasmin Gabay, graduate student at the Tel Aviv University.

Researchers found that tissue-covered soft corals were less likely to be damaged by the acidic water than bare skeleton of the coral.

"We found that the soft coral's tissue may indeed protect the skeleton from declining pH levels," said Yasmin Gabay in a news release. "The organism's internal environment apparently has a mechanism that protects against the acidic conditions."

According to Prof. Benayahu, the future of soft corals is still unclear. These corals don't build the massive reefs because they take long to calcify. However, they can live under harsh conditions and are replacing stony corals in oceans.

A recent study had shown that the spectacular Great Barrier Reef grew during the last ice age and has survived a wide range of temperatures.