Coral reefs have become a focus for observation and study due to their economic and ecological importance and sensitivity to warming ocean temperatures.
At a time when climate change is increasingly difficult to ignore, its devastating effects on our environment and ecosystems are becoming more apparent.
“30 per cent of all of the ocean species have a home in coral reefs,” explained Dr. Emily S. Darling, a Banting Postdoctoral Fellow in the Department of Ecology and Evolutionary Biology and an Associate Conservation Scientist with the Wildlife Conservation Society’s Marine Program. “They are also incredibly important for society, so half a billion people on the planet who live in the tropics depend on coral reefs for food security, their livelihood, coastal protection and cultural practices.”
From 2014–2016, bleaching events have increasingly devastated coral reef populations around the globe. Bleaching events occur when coral reefs, under duress from harsh environmental conditions, expel the photosynthetic algae that they have a symbiotic relationship with.
Though not deadly in itself, the breakdown of this symbiotic relationship is stressful to the corals and has long-term health implications that can lead to death in some cases.
To minimize the effects of climate change on the environment, it is important to understand a habitat’s threshold for change and how species can resist adverse effects and bounce back from them — their resilience.
Ecological resilience is an important principle for every ecosystem, but the drastic impact of climate change on fragile coral reefs provides an opportunity for insight into the process.
Resistance and recovery capture the two aspects of ecological resilience that hint at how ecosystems persevere after a disturbance. A study published this year in Science found that a relative increase in the frequency of bleaching events results in a lower likelihood of the ability of slow growing coral species to recover.
According to Darling, resilience can be categorized in two ways: the intrinsic resistance of species with inherited physical traits that are better suited to the changing environment, and the extrinsic resistance that results from inhabiting an environment resilient to climatic disturbances.
Due to concerns that climate change and bleaching are happening too fast, efforts are underway to identify ‘super coral’ species that have natural traits helpful for survival and to potentially genetically engineer such traits into existing species.
Extrinsic resistance might be sought through the ‘reefs of hope,’ a group of reefs sheltered from bleaching and predators. These reefs are also connected to other reefs through ocean currents, allowing them to potentially seed and repopulate lost coral habitats.
Another way to combat coral reef loss is to artificially replenish coral reef territory. Darling noted, however, that doing so comes with technical drawbacks.
“It is very, very expensive, to even replant a few square meters of a real reef, so [the] question is ‘how do we scale that up to go to the hundreds of species of coral that build reefs?’”
While there is still a ways to go, methods to promote ecological resilience in ecosystems will provide a defense from the inevitable habitat loss that will ensue as a result of climate change.
Yet, there is a limit to the damage the environment can take.
“There will be no solutions if climate change continues as business as usual and if there is no political will and momentum to actually deal with our carbon problems,” said Darling.
She added that having already lost half the worldwide coral population, estimates suggest that we may lose up to 90 per cent by 2050 if climate change is not adequately addressed.
Mundane but consequential human activities contribute to coral reef destruction, such as the consumption of single-use plastics. There are an estimated 11 billion pieces of plastic on coral reefs, which can cause disease in coral reefs or smother them to death.
Darling praised Catherine McKenna, Canada’s Minister of Environment and Climate Change for her efforts to push a zero plastic policy in Canada at the World Ocean Summit in Mexico earlier in March.
“It’s not just natural ecosystems that have to keep up with climate change, or change or adapt,” said Darling. “It’s also our societies.”
Despite not having coral reefs to save here in Canada, Darling believes that conservation work starts at home.
“One leading way is to build, adapt capacity, or collective action around groups of people to be able to make positive change,” said Darling, “[and] really transform the way that we engage with the future climate… towards sustainability.”