By Gerry T. Estrera
Ecologically-fragile coral reefs, touted to be the rainforests of the sea, may be able to adapt to moderate climate warming, thus improving their chance of surviving through the end of this century.
 “Only if there are large reductions in carbon dioxide emissions,” said a study funded by US National Oceanic and Atmospheric Administration (NOAA). The study was researched by the agency’s scientists and its academic partners, the California State University and the University of British Columbia.
 Results further suggest corals have already adapted to part of the warming that has occurred in recent years.
 “Earlier modeling work suggested that coral reefs would be gone by the middle of this century. Our study shows that if corals can adapt to warming that has occurred over the past 40 to 60 years, some coral reefs may persist through the end of this century,” said study lead author, Dr. Cheryl Logan, an assistant professor in California State University Monterey Bay’s Division of Science and Environmental Policy.
 Warm water can contribute to a potentially fatal process known as coral “bleaching,” in which reef-building corals eject algae living inside their tissues. Corals bleach when oceans warm only 1-2°C (2-4°F) above normal summertime temperatures. Because those algae supply the coral with most of its food, prolonged bleaching and associated disease often kills corals.
 Dr. Terry Hughes, a distinguished professor at James Cook University in Australia, said that as climate change intensifies, coral bleaching would also increase at an unprecedented level. “Bleaching events are expected to increase in terms of frequency,” he pointed out.
 “The surface of the world’s oceans has warmed by 0.7°Centigrade, resulting in unprecedented coral bleaching and mortality events,” said the Consensus Statement released during the opening of the 2012 International Coral Reef Symposium (ICRS) held in Cairns, Australia.
 In a series of journals some years back, Science reported that climate change could trigger the death of coral reefs, with coral bleaching being the clearest sign. A particularly severe, worldwide bleaching event occurred in 1998, effectively destroying 16 percent of the world’s reefs. Some areas lost 50-90 percent of their coral in this single event.
 In 2010, as much as 95% of the corals in the Philippines suffered bleaching after a warming event. “The bleaching has been observed at many other sites around the Philippines featuring mass mortality of corals,” a news report said.
 The NOAA study explores a range of possible coral adaptive responses to thermal stress previously identified by the scientific community. It suggests that coral reefs may be more resilient than previously thought due to past studies that did not consider effects of possible adaptation.
 When asked whether the same phenomenon is happening in the Philippines, Dr. Theresa Mundita S. Lim replied, “There are actually already studies that show that some of our coral reef areas are more resilient to coral bleaching than others.”
 Dr. Lim, the director of Biodiversity Management Bureau, cited those coral reefs teeming within Verde Island passage and those in Tubbataha. Bleached coral reefs in these areas, she said, “recover more quickly.”
 The key, she said, is “to maintain these areas so that they can adapt faster and recover more quickly than the rate they are being destroyed by overfishing, unsustainable fishing practices, and siltation, among others.”
 Healthy coral reef areas, Dr. Lim pointed out, “adapt better.”
 The NOAA study projected that, through genetic adaptation, the reefs could reduce the currently projected rate of temperature-induced bleaching by 20 to 80 percent of levels expected by the year 2100, if there are large reductions in carbon dioxide emissions.
 “The hope this work brings is only achieved if there is significant reduction of human-related emissions of heat-trapping gases,” said Dr. Mark Eakin, who serves as director of the NOAA Coral Reef Watch monitoring program, which tracks bleaching events worldwide. “Adaptation provides no significant slowing in the loss of coral reefs if we continue to increase our rate of fossil fuel use.”
 While the study focuses on ocean warming, many other general threats to coral species have been documented to exist that affect their long-term survival, such as coral disease, ocean acidification, and sedimentation. Other threats to corals are sea-level rise, pollution, storm damage, destructive fishing practices, and direct harvest for ornamental trade.
 The Philippines is part of the so-called Coral Triangle, which contains nearly 73,000 square kilometers of coral reefs – that’s 29 percent of the global total. Aside from the Philippines, it also includes Indonesia, Malaysia, Papua New Guinea, Solomon Islands, and Timor-Leste.
 Spanning the marine waters of insular Southeast Asia and the western Pacific, the Coral Triangle is recognized as the global center of marine biological diversity. It has the highest coral diversity in the world (76 percent of all coral species) as well as the highest diversity of coral reef fishes in the world (37 percent of all species).
 “The health and livelihoods of approximately 240 million people in the region are currently sustained by the significant biodiversity and ecosystems of the Coral Triangle,” said a part of the Australian Government Support Plan for the Coral Triangle Initiative on Coral Reefs, Fisheries, and Food Security. “It is a source of food, income, and protection from severe weather events. The ongoing health of these ecosystems is critical for the people of the region.”
 Meanwhile, the NOAA study calls for further research to test the rate and limit of different adaptive responses for coral species across latitudes and ocean basins to determine if, and how much, corals can actually respond to increasing thermal stress.
 “Not all species will be able to adapt fast enough or to the same extent, so coral communities will look and function differently than they do today,” Dr. Logan said in a statement.
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