Last week, the Australian Research Council reported the results of an aerial and underwater survey of the Great Barrier Reef. While I generally don’t like to comment on unpublished works, this study has been generating a lot of media attention. The ARC Press Release states that a shocking 93% of the 1,400 mile (2,300 km) long reef has been affected by coral bleaching. And in the northern section, less than 1% of the 522 reefs surveyed showed no evidence of bleaching.
Corals are symbiants – species that are in very close association with one another. The reefs are made up of individual animals with hard exoskeletons that aggregate into colonies. Each coral polyp is home to numerous single-celled plants that provide the animal with energy. In return, the algae is provided with safe housing inside and is able to use nutrients from the coral’s waste.
When coral polyps are stressed – from pollution, desiccation, or changes in temperature or solar radiation – they eject the algae. Because the algae contribute to the coral’s color, we call this coral bleaching. Bleaching can serve to increase the short-term survival of the coral, but if the stressful conditions persist, it will eventually die.
While the Great Barrier Reef is an iconic natural wonder, it isn’t the only place mass-bleaching is occurring and this isn’t the first time it’s happened. Late last year, the National Oceanic and Atmospheric Administration officially declared a global mass-bleaching event – the third in recorded history. The bleaching event began in the North Pacific Ocean in the summer of 2014 and has since expanded across the Pacific and Indian Oceans and the Caribbean Sea. Researchers believe that by the end of 2015, almost 95% of US coral reefs had been exposed to bleaching conditions.
And there’s more bad news. A study published this month found that this is only the beginning. Researchers now believe that the structure of coral reefs have insulated them from bleaching and mortality during past streaks of warmer weather. They predict that an increase in local temperature as small as 0.5°C would result in the loss of this insulating mechanism.
This means that an increase in ocean temperature of 0.5°C may result in the rapid degradation of the Great Barrier Reef. If you’ve been putting off that vacation to check out the Great Barrier Reef – or any reef, for that matter – it might be time to book your flights.