Who Can Save Dying Reefs? Fish!

In 2009, marine scientist Enric Sala led a National Geographic Society team to Kiribati, about 1800 miles south of Hawaii, to see if the vibrant and virtually untouched reefs there held any clues to bringing damaged reefs back to health.

"The bottom was covered by thriving coral. It was, like, crystal-clear, blue, turquoise water, schools of silver jacks. And then the corals, pastels, oranges, and beiges - it was like an impressionist painting," Sala said.

His team presented their findings to Kiribati officials, and the government took steps to protect the waters from fishing and other human activity. However, between 2015 and 2016, record levels of ocean warming decimated half the coral reefs the team had been studying.

After hearing that news, they lost hope for the health of coral reefs, but the study continued, and last year, they went in for another dive. Despite the reported conditions, the reef had somehow restored itself and was filled with life and color. Sala was elated. This resurrection, Sala says, can be traced to two key factors.

First, thankfully, half of the corals had remained alive. Despite the rise in temperatures, there were enough surviving corals left behind to help reproduce and replenish the reefs.

The second factor was the Kiribati government's decision to protect those waters fully.

"It has an abundance of fish that is off the charts. So they were eating all the algae that would smother the dead coral skeletons and make it impossible for the corals to come back, which is what happens in other places like the Caribbean," Sala explained.

Protecting oceans from overfishing, Sala added, allows the ecosystem to become more resilient. In highly protected areas, the populations of fish grow so much that they spill over the boundaries of their areas and help replenish surrounding fishing grounds.

"So if countries want a future for the fisheries, they need to manage their fisheries in a more responsible way around areas that are set aside to help regenerate the rest of the ocean," Sala said.

- Jon Betz/National Geographic