It is surprising, however, that by 2010 global coral coverage was almost back to pre-1998 levels. “This is good news,” says Sutter. “Although the reefs have fallen, they are back again.” When “old” reefs are wiped out, the new species that move in are often faster-growing, weed species (just as with trees after wildfires), Sutter says. It’s great to have this growth, he says, but these opportunistic corals are often more susceptible to disease, heat, and storms.
Global decline has been the trend since 2010, with coral dropping below 1998 levels. This is due in large part to two other global bleaching events, in 2010 and 2015-2017, in which coral has not been sufficiently deferred. There has been a slight 2 percent rise in live corals since 2019, although it is too early to say if that will continue. “If you’re a really optimistic person, you might say this happened even when the temperatures were high, so we’d probably see an adaptation,” Sutter says.
During the long, stable, and relatively healthy period of reefs in the 1990s and early 2000s, the average reef was about 30 percent live hard corals and 15 percent macroalgae such as seaweed and turf. This is twice the amount of algae in corals. Since 2009, that percentage has fallen to about 1.5 with coral macroalgae blooms down 20 percent. While seagrass also creates a productive ecosystem, unlike the intricate architecture that coral reefs make, it supports different fish.
Encouragingly, the Coral Triangle in East Asia stands out as a bold exception. This region contains nearly a third of the world’s coral reefs – and hosts an abnormally large more live hard coral and less macroalgae today than in the early 1980s, despite warmer waters. This thinks it thanks genetic diversity Among the 600 species of corals in the area, allowing corals to adapt to warmer waters. “The diversity probably provided some protection,” Sutter says, while a healthy population of herbivorous fish and hedgehogs keeps the seagrass low.
The other three major global regions of coral reefs – the Pacific Ocean, which absorbs more than a quarter of the global total; Australia at 16 percent; and the Caribbean, at 10 percent—all of which host fewer coral reefs today than when the measurements began. “The Caribbean is a really tragic and desperate situation,” says Voolstra, where there are only 50 or so species of corals. new disease eliminate them.
Sutter adds that everything could be worse. “The reefs are probably, on average, doing better than I imagined,” he says. “The fact that corals retain the ability to bounce back, that’s amazing.”
In the face of extreme conditions, coral reef advocates globally are actively working to protect and restore coral reefs from pollution. One recent studyLed by Lisa Bostrom-Einarson of James Cook University in Australia, she searched the literature and found more than 360 coral restoration projects in 56 countries. Most focus on transplanting portions of coral from a thriving spot to a struggling area, or “gardening” the reefs in nurseries and transplanting them outside. It also includes innovative efforts such as using electricity To induce calcification on artificial corals (an old but still controversial idea), use a diamond saw to cut away the fine, fast-growing fragments of slow-growing corals.