Coral Reefs Could Survive Longer In Warming Planet Than Previously Thought
Coral are already a dying class, and rising ocean temperatures could eventually wipe them out altogether. But recently scientists have discovered a population of coral off the coast of American Samoa that shows surprising resilience in warm waters, offering cold comfort suggesting they'll last longer than we thought in the face of global warming. "Adding these adaptive abilities to ecosystem models is likely to slow predictions of demise for coral reef ecosystems," wrote the authors of a new study, published this week in the journal Science.
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The fascinating thing about this particular type of coral, called Acropora hyacinthus, is that it doesn't adapt by evolution alone. Rather, individuals could adjust to warmer water. In effect, they were able to "buy more time to evolve the necessary adaptations by using acclimatization as a first line of response," Christian Voolstra, a coral geneticist who was not part of the research team, told Nature.
Corals are a kind of invertibrate marine animal within the phylum cnydaria, the same phylum to which jellyfish belong. Coral reefs often derive their energy from a symbiotic relationship with algae, which use photosynthesis and give reefs their brown color. But when the temperature around them increases, they discharge the algae. This is known as bleaching.
In this study, scientists uprooted hardy coral accustomed to temperature swings and placed them in warm water to test the extent to which they bleached. They compared these to more wimpy coral — ones accustomed to cooler water and less variability. As predicted, the hardy coral were less vulnerable to the heat. By way of natural selection over generations of offspring, they had adapted.
In a second test, they moved cold-water coral into hot water and tracked their ability to adapt, as well as the expression of 74 genes believed to be important for acclimation, over 27 months. Over time, these coral became "more resistant to bleaching," Nature reported. The authors believe A. hyacinthus has dormant genes that can fire when necessary to stave off bleaching.
"In less than two years, acclimatization achieves the same heat tolerance that we would expect from strong natural selection over many generations for these long-lived organisms," the scientists wrote. In other words, this species could prevent bleaching in warm water by both dealing with it and by passing on favorable traits to their offspring. With more research, more climate change-resistant species could be identified.
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