Scientists seek clues to save reef ecosystems

The first-ever video of coral bleaching, released last week by researchers from Australia’s Queensland University of Technology, has shocked environmentalists across the world. Though scientists have long warned of coral bleaching events, precipitated by global warming, few knew the phenomenon could be so violent.The Australian researchers found that under simulated warming conditions, solitary mushroom coral called Heliofungia actiniformis will swell and squeeze, dramatically expelling their algal tenants. The eight-day time-lapse video, which has gone viral on the Internet, brings coral to life for viewers who may be more accustomed to thinking about reefs as habitats rather than animals and bleaching as a passive event.Andrea Grottoli, a professor of earth sciences at Ohio State University, told The Christian Science Monitor (CSM) that the video is a much more vivid way of conveying the science to the public and adds emotional content to something we know.As pointed out by the CSM, the relationship between coral and algae is a prime example of symbiosis in the animal world. “Coral polyps provide a perfect protective home for tiny zooxanthellae algae. In exchange, the photosynthetic algae provide nutrients and colour to their (naturally colourless) coral landlords. But if sea temperatures rise even a few degrees over the normal thermal maximum, corals will begin to expel algae from their bodies and turn white. The whole bleaching process can take as few as 10 days.”Algae will return to their hosts if temperatures cool. If the heat does not let up, bleached coral may die. And as climate warming shows no sign of slowing, researchers fear the worst for coral ecosystems.Temperature is the single largest stressor facing modern coral reefs, and currently the world is witnessing annual bleaching events, despite predictions that the phenomenon would not occur for several decades. Climate change presents a distinctly long-term challenge for conservationists. But marine scientists are already working toward short-term solutions for maintaining coral health. And by better understanding the mechanics behind bleaching, researchers could target conservation efforts where they count the most.According to Grottoli, there are things that can buy time for coral reefs. Reefs that are protected or isolated from human impact tend to recover more quickly from bleaching. And even on bleached reefs, there are some colonies that do not bleach. So scientists are trying to identify what makes those individual corals resilient when other individuals are bleaching.In a previous study led by Grottoli, researchers found that coral with higher fat reserves were better able to survive and bounce back from bleaching events. In a different paper, Australian researchers theorised that coral microbiomes could hold clues to saving reef ecosystems.The next step is to look through that kind of microbial soup and find which bacteria may be the beneficial ones, understand how they are responding under temperature changes, and what contributions they are making to the coral, as suggested to the CSM by Tracy Ainsworth, a molecular biologist at Australia’s James Cook University.The relationship between coral and algae is a prime example of symbiosis in the animal world