Healthy coral in the Solomon Islands. Emily Darling/WCS


Scientists suggest protecting ‘reefs of hope’ may offset climate-change damage to coral reefs

April 20, 2018

By Diane Mar-Nicolle

Among the most damaging effects that climate change has wrought on the natural world are those sustained by coral reefs.

Bleaching, as it is commonly known, occurs when coral is exposed to warmer ocean temperatures, water pollutants, over-exposure to sunlight and extreme low tides. Under any of these conditions, coral expel algae living in their tissue, which turns the coral white and fragile. If the conditions last long enough, the corals starve and die.

Despite this grim scenario, SFU alumnus Emily Darling and marine biology professor Isabelle Côté are hopeful that all is not lost for coral reefs.

In their paper, published recently in Science, the authors point out various approaches that scientists are starting to adopt in hopes of saving reefs from climate change. These include selective breeding or genetic engineering to increase corals’ resistance to warmer, more acidic oceans.

While the authors applaud any and all efforts to save the reefs, they say such approaches are partial solutions at best.

“Right now, it isn’t realistic to think that we can cost-effectively restore high-diversity reefs at scales of hundreds or thousands of square kilometers using these methods,” says Darling.

Instead, the duo suggests resources might be better spent finding and protecting ‘reefs of hope’—rare coral reefs that appear to have a lower risk of exposure to bleaching and predator outbreaks.

Protecting these reefs would ensure their coral larvae can travel, via shared ocean currents, to more vulnerable reefs.

While the authors concede that eliminating greenhouse gas emissions is the ultimate solution, “finding and protecting even the smallest of resistant refuges is an urgent priority for global conservation efforts.”

Without preventative measures, Côté and Darling predict that coral reefs will be transformed beyond recognition in the coming decades.

“Weedier corals, algae and sponges do not calcify carbonate reef architectures,” they say. “This can result in slower-growing reefs, flatter reefs and reefs that are more likely to erode and break apart.”

Not only will critical ocean ecosystems be affected by the worldwide transformation of coral reefs, so will society.

“These changes will force some societies to transform away from current reef-dependent livelihoods, like fishing or tourism,” Darling says.

Côté cautions, “We cannot overstate how dire the outlook is for coral reefs because of climate change. The ultimate cause of all these ills is, without doubt, carbon emissions. We can buy ourselves some time with selective breeding and strategic choices of which reefs we protect, but at the end of the day, if we don't curb emissions, we will lose reefs as we know them today.”

Bleached corals from abnormally hot ocean waters in Madagascar in 2016. Stephanie D'agata/WCS