Bright Areas of the Global Coral Reef Catastrophe
Surprisingly, however, 2010 global coral coverage almost returned to pre-1998 levels. “That’s good news,” Souter said. “Even if the reefs fall, they rise again.” When “old-growing” corals are wiped out, new ones move to usually faster-growing, weedy species (like trees after a forest fire), Souter said. It’s nice to have this growth, he said, but these opportunistic corals are always more vulnerable to disease, heat, and storms.
A global decline has largely been the trend since 2010, with corals sinking back below 1998. This is due in large part to two more global bleaching events, in 2010 and 2015. -2017, where corals have not yet been adequately paid. There has been a small, 2 percent increase in live coral since 2019, though it will soon be announced if it will continue. “If you’re an optimistic person you can tell it happens even when the temperature is high, so maybe we’ve seen an adjustment,” Souter said.
During the long, relatively strong and healthy season for corals in the 1990s and early 2000s, the average reef was about 30 percent live hard coral and 15 percent macroalgae such as seaweeds and turf. It is twice as much coral than algae. Since 2009, that ratio has dropped to about 1.5 while reef macroalgae has increased by 20 percent. While seaweed also makes for a productive ecosystem, it is not the same as the complex architecture created by reefs, and it supports a variety of fish.
Encouragingly, the Coral Triangle of East Asia appears to be a bold exception. This region holds nearly a third of the world’s coral reefs — and it doesn’t normally host more survive hard coral and very little macroalgae today than in the early 1980s, despite rising water temperatures. Thought that thanks to genetic diversity among the region’s 600 coral species, allowing corals to adapt to warm water. “Perhaps diversity has provided some protection,” Souter said, while healthy populations of herbivorous fish and urchins control marine weeds.
The other three major global regions for coral — the Pacific, hold more than a quarter of the world’s total; Australia, with 16 per cent; and the Caribbean, with 10 percent — all much less coral now than when the measurements began. “The Caribbean is a terrible and desperate case,” said Voolstra, who has 50 or more coral species and a new disease wiping them.
It could be even worse, Souter added. “The reefs are probably, for the most part, better than I thought,” he said. “The fact that the reefs retain the ability to bounce back, that’s amazing.”
In the face of punitive conditions, coral conservationists around the world are working to protect corals from pollution and to actively restore them. In a recent study, led by Lisa Boström-Einarsson of James Cook University in Australia, has read the literature and found more than 360 coral restoration projects in 56 countries. Most focus on transplanting coral fragments from a fertile area to a difficult one, or “planting” young corals in nurseries and planting them. They also include new efforts such as using electricity to induce calcification of artificial reefs (an old but still controversial idea), and to use a diamond blade to cut small, fast-growing microfragments from slow-growing reefs. corals.