Bleached coral in the Great Barrier Reef in 2006. (AP/Ove Hoegh-Guldberg)
Anybody who has been visiting coral reefs for the past 20 years or so will tell you that the scene underwater pales – quite literally – in comparison to what it used to be.
New research published in PLoS ONE yesterday shows that coral bleaching in the Atlantic and the Caribbean in 2005 was the worst bleaching event ever recorded in the region. That year, more than 80% of the corals studied by researchers from 22 countries bleached, and 40% of it died. Scientists at the National Oceanic and Atmospheric Administration (NOAA) think this year could rival 2005. Corals in the Caribbean are already bleaching again – in some cases worse than five years ago.
When you’re snorkeling over a coral reef, it’s easy to think of the coral formations you see as inanimate parts of the landscape. They’re not. In fact, corals are an exquisitely refined species; a symbiotic partnership of coral polyps that host a special kind of algae, which in turn photosynthesizes food for the polyps to grow and build themselves. The species as a whole (there are many different kinds of corals in coral reefs) are the backbone of their environment, providing food and shelter to thousands of other species, from sea cucumbers all the way up the food chain to sharks and humans. For us, coral reefs, by NOAA’s estimates, generate up to $375 billion every year in jobs, food and tourism.
Despite that critical role, corals are extremely finicky. They don’t respond well to change – particularly changes in the water they live in. When water temperatures rise, the corals expel their guest algae, causing the structure to turn white, or bleach. If the water continues to stay warm, the corals eventually starve to death without the algae’s food, and with the corals death the entire system that lives on them starts to follow. Add this to the host of other challenges that coral reefs face – oceans’ increasing acidity (they don’t like that either), water pollution and overfishing – and some scientists think coral-dominated reefs could disappear in the next 40 years.
Bleaching has been on coral watchers’ radars since 1998, when the world’s worst recorded incident of global bleaching occurred and 16% of the world’s reefs died. This year things are looking grim too. (Here’s a map where you can see bleaching hot spots this year in the Caribbean as monitored by NOAA.) While the majority of corals recover from bleaching, re-integrating algae once water temperatures cool down, repeated occurrences of periods of stress could affect the animals’ ability to recover.
What can we do to ensure that reefs aren’t wiped in a matter of decades? Well, getting a greener energy economy online as fast as possible to curb the trend of rising ocean temperatures is the long answer. The short answer probably lies in mandating that the sectors that profit directly from coral reefs — primarily fishing and tourism — get more involved. There are a couple of very cool programs like Reef Check and CoralWatch that train tourists how to visually monitor coral reef health and report their findings back to the organizations. That helps build statistics and drive education, which in turn might encourage the market to favor dive operators and seafood brands that operate more sustainably in their delicate environments.
Is that enough? Probably not. Is it better than nothing? Without question.