Some coral reefs are thriving, and scientists say they may guide efforts to curb threats such as overfishing and climate change that are blamed for widespread global declines.
A major new study identified 15 “bright spots” among more than 2,500 coral reefs in 46 nations — including off Indonesia, the Solomon Islands and Kiribati — where there were far more fish than predicted.
And Australia’s Great Barrier Reef, the world’s biggest, was performing in line with expectations, given its remoteness and high level of protection, said Joshua Cinner, a professor at James Cook University in Australia and lead author of the study published Wednesday in the journal Nature.
Australian Prime Minister Malcolm Turnbull, facing a tight reelection battle, has pledged $740 million for the reef, which scientists say is suffering widespread coral bleaching due to climate change.
The report found that in many of the bright spots, local people depended heavily on reefs for food and took part in owning and managing fish stocks, while many of the reefs also had deep waters nearby that fish could use as a refuge.
“People invest in creative solutions when their livelihoods depend on it,” Cinner said.
The study also identified 35 “dark spots,” in such places as Jamaica and Tanzania, where there were fewer fish than expected. In many of those areas, fishermen used nets that could snag and damage reefs. They also had access to freezers, which gave an incentive to catch and store extra fish, depleting stocks.
Another factor was that reefs with dark spots had recently suffered an environmental shock, such as from a cyclone or from a rise in water temperatures that can bleach reefs.
“We can learn things from the bright spots about what to encourage,” Nicholas Graham of Britain’s Lancaster University said.
The authors stressed that bright spots were not those with the most fish but were places that were outperforming expectations judged against baselines such as the size of local population, tourism and whether reefs were in a marine reserve.
Cinner said the study was unable to include all possible factors due to a lack of data, including the battering that reefs get from waves. Reefs with high “wave energy” typically have fewer places for fish to grow and hide.
The study involved 39 scientists from 34 universities and conservation groups.