Faced with warming seas and acidic water, coral reefs across the globe are suffering unprecedented levels of bleaching and death. The problem is well documented in Hawaii’s stunning reefs and even the iconic Great Barrier Reef down under. Now, it looks like Japan’s largest and most gorgeous reef is also on the same doomed journey.
A government survey of Sekisei Lagoon in southwestern Japan near Okinawa has found that just 1.4 percent of the coral reef is healthy, as reported by AFP. Splashed with vibrant color and rich in life, the reef spans for approximately 20 kilometers (12.4 miles) by 15 kilometers (9.3 miles) and contains more than 350 coral species. Its damage was assessed using over 1,000 satellite images of Sekisei Lagoon and two other reefs around the Ishigaki and Iriomote islets of the Okinawa Prefecture.
To add further salt to the wound, Japan's Environment Ministry reported last year that 70 percent of the reef was dead, with up to 90 percent of it suffering from heavy bleaching, a level that could take decades to recover from.
All in all, it’s a pretty bleak picture.
Corals get their gorgeous colors from the microalgae that live symbiotically with them. If they are subjected to stress – such as warming temperatures, too much light, water acidification, or pollution – the microalgae flee the coral, leaving them a sickly pale color and in poor health, a process known as bleaching for obvious reasons.
The problem faced by Japan's reefs has been in the works for some decades. A previous survey in 1991 estimated that nearly 15 percent of the coral reef was healthy. Much of these patterns come in waves as a large bleaching episode, often driven by weather events like El Niño, is often followed by a period of recovery. Nevertheless, the reef appears to have not recovered significantly since 2008, when the proportion of healthy coral was as low as 0.8 percent.
Climate change is “the greatest global threat” to coral reef ecosystems, according to the National Oceanic and Atmospheric Administration (NOAA). Along with rising sea surface temperatures, carbon dioxide absorbed into the ocean from the atmosphere decreases the water's pH, making it more acidic and hostile to life.
This isn't just terrible news for Okinawa's scuba diving enthusiasts, it also has the potential to wreak havoc on the thousands of fantastic beasts that rely on the reefs. Coral reefs are a central part of the world’s marine life. Although they cover less than 1 percent of Earth's marine environment, they are home to more than 25 percent of marine life.
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