Can a coral reef die?

Can a coral reef die?

An inaccurate (and possibly tongue in cheek) article went viral and triggered many crying-emojis on the internet over the past few days. Its bold claim? “The Great Barrier Reef is dead, RIP.” The reality is a little less bleak and more nuanced, but when is a reef, or any other ecosystem made up of thousands upon thousands of different species, “dead”? And can it come back?

img_6392Bleached corals dot the back reef in Okinawa, which, like much of the globe, experienced severe bleaching this year (photo by the author).

 

First, just some brief fact checking: the Great Barrier Reef is not dead. This claim arises, however, from an alarming fact: last Austral summer (so winter 2015-16 for us Northern Hemisphere folks), a record number of corals on the GBR, particularly in the north, bleached and died. This happened because the El Niño conditions at the time were among the strongest ever, making the ocean much, much warmer than usual. Corals can live in a wide variety of environments, but this sort of sudden change (which will likely become more common as the planet warms) upsets the balance between corals and the tiny algae that live in their tissues and provide the corals with food. The corals expel the algae, and then they starve to death.

This is also not the first time this has happened. The 1998/1999 El Niño was of similar strength, and sparked a similarly devastating global bleaching event. But while many reefs lost most of their corals during that El Niño, some recovered their hard corals and some did not. Some grew back as soft coral communities rather than reefs, while others were reborn as unsightly algae beds. Now that this El Niño has ended, the same will likely be true for the Great Barrier Reef. Ten years from now, corals will have grown back in places, and others will be unrecognizable, possibly barren, possibly replaced by ecosystems that are unlike anything we’ve seen before. Scientists will work hard to try to understand why some reefs are resilient and others aren’t, and these ecosystems will continue to die and regrow and change as the planet heats up.

We are entering (or, more accurately, have already entered) an era of great change for this planet. The ecosystems of 2116 will undoubtedly differ greatly from those today – but we may have the power to guide these changes. By limiting carbon emissions as much as possible, investing in scientific research, and using this knowledge to manage natural resources in new and creative ways, we can avoid the worst of all possible outcomes, and hopefully preserve much of the earth’s biodiversity. I believe this article achieved its goal of starting conversation about the perils faced by reefs among people who never would have thought about it otherwise. While some are worried that the article prompted fatalism among those who took it literally – were these people really about to save coral reefs anyway?

A reef can die, but it can also be reborn. We may not have been able to stop this bleaching event, but the actions we take over the next few decades will determine the fate of these ecosystems, and all ecosystems, as our planet continues to warm.

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