The encouraging conclusion belongs to a new study

Mar 10, 2012 11:32 GMT  ·  By
(Top) Unexpected survival of fast-growing Malaysian coral in a 2010 bleaching event that killed a larger, slow-growing coral beside it. (Bottom) The reverse happened in Indonesian corals during the same event
   (Top) Unexpected survival of fast-growing Malaysian coral in a 2010 bleaching event that killed a larger, slow-growing coral beside it. (Bottom) The reverse happened in Indonesian corals during the same event

As increased amounts of atmospheric greenhouse gases drive ocean acidification at ever-increasing speeds, marine species living around coral reefs come under severe threat. Now, a study demonstrates that some of those species could potentially survive acidification, at least for a while.

A few coral species have demonstrated a remarkable ability to endure under extremely-adverse conditions, by adapting to their new environments. While most corals are not so lucky, it could be that not all of them will disappear as the world's waters turn acidic.

Details of the new investigation appear in the latest issue of PLoS ONE, a peer-reviewed journal published by the Public Library of Sciences. The work was carried out by an international collaboration of investigators, led by scientists at the University of New South Wales (UNSW), in Australia.

The conclusion is largely based on an analysis of a coral population living in southeastern Asian waters, which managed to survive a mass bleaching event in 1998 and 2010. Coral bleaching occurs as the organisms separate from their support structures, and then drift away.

“Mass coral-bleaching events, caused by a breakdown in the relationship between the coral animals and their symbiotic algae, are strongly correlated with unusually high sea temperatures and have led to widespread reef degradation in recent decades,” explains lead study author, Dr. James Guest.

The expert currently holds joint appointments as a research fellow, at the UNSW Center for Marine Bio-innovation, and with the Advanced Environmental Biotechnology Center at the Nanyang Technological University, in Singapore, EurekAlert reports.

One of the main conclusions of the new study is that less hardy, fast-growing branching coral species will be replaced by hardier, slow-growing massive species, if ocean acidification is allowed to progress unchallenged.

During the 2010 mass bleaching event, roughly 90 percent of fast-growing corals perished. However, those that survived may have done so due to the aid of adaptations they gained during the 1998 event.

“The most parsimonious explanation, therefore, is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. This is controversial because many scientists believe that corals have exhausted their capacity to adapt to thermal stress,” Guest says.

“The results of the present study do indicate, however, that the effects of coral bleaching will not be as uniform as previously thought and fast-growing branching taxa such as Acropora and Pocillopora are likely to persist in some locations despite increases in the frequency of thermal stress events,” he concludes.