The past few decades haven’t been kind to Australia’s majestic Great Barrier Reef.
Since 1985, half the reef’s coral has been ravaged by tropical storms, invasive crown-of-thorns starfish, disease, and coral bleaching driven by rising ocean temperatures. This past March, due to El Niño and global warming, an unprecedented bleaching event in the northern third of the reef turned 95 percent of corals a ghastly bone white.
Usually when disaster befalls coral reefs, they take about 10 or 20 years to bounce back. The problem is that they don’t always get that much time to recover, especially now that global warming is making severe bleaching events more common and human activities like fishing and pollution keep expanding.
So that’s the grim news. The good news is that the Great Barrier Reef and other reefs worldwide have valuable allies that can help them hang on: rabbitfish, parrotfish, and other brightly colored fish species that can aid recovery. We just have to make sure those fish are free to do their job.
A new study in Ecology Letters, led by Camille Mellin of the University of Adelaide, found that when fishing bans are put in place around the Great Barrier Reef, the local coral recover much more quickly from disaster. The researchers looked at 46 different reefs across 20 years, and this pattern emerged quite clearly.
The key chart showS coral recovery in places within marine protected areas that ban fishing (in green) versus those without protection (in red). The protected areas recover significantly faster after bleaching events, starfish invasions, disease, and major storms.
Scientists have known for a while that certain fish help maintain the health of reefs by clearing away harmful algae that would otherwise smother the coral. In 2008, researchers recorded the rabbitfish playing this crucial role in the Great Barrier Reef. In the Caribbean, the stoplight parrotfish seems to be a key algae muncher. Other species of parrotfish and surgeonfish appear to be invaluable for protecting reefs around the world.
The problem is that many of these herbivore fish populations have been declining over time, due to heavy fishing. This new study suggests that protecting these fish would help aid reefs that provide billions in benefits for tourism and shoreline protection.
Currently, about half of the Great Barrier Reef Marine Park is off limits to fishing fleets. But that still leaves vast swaths of the park unprotected. Figuring out which species, exactly, are most important to reef health in different areas might make fishing restrictions easier to tailor the paper mentions that that’s the next big research step.
This study on fish and reef health doesn’t come in isolation. In 2014, a report from the Global Coral Reef Monitoring Network warned that many Caribbean reefs could disappear “within a few decades.” That paper emphasized the importance of protecting the stoplight parrotfish by limiting spearfishing and banning certain traps.
The paper noted that in places like Bermuda and Belize that have parrotfish protections, reefs have sprung back much more quickly after devastating hurricanes.
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