The Florida Barrier Reef's Last Stand

Summer heat this year posed an existential threat to the world's third-largest barrier reef.

The race to save the only barrier reef in the U.S. hit a major setback this summer when a heat wave turned the waters off the Florida Keys into a Jacuzzi.

The Florida Reef Tract is used to weathering warm water during fall months, but unseasonably hot water arrived this summer, meaning those coral colonies had to endure months of extreme water temperatures. A buoy off Florida recorded 101-degree water temperatures this July. When corals are stressed by hot or cold water, they lose their color—a result of expelling algae that provides corals with most of their energy—and eventually die.

Throughout the summer and into early October, the National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch program placed the Florida Keys under a coral bleaching Alert Level 2, meaning significant bleaching is expected with likely mortality.

The bleaching was heartbreaking for researchers and volunteers trying to save the reefs—and an existential threat to the third-largest barrier reef in the world. Over the past 50 years, 97 percent of the Florida Reef Tract's historical cover has died due to overlapping environmental pressures: pollution, bleaching events, and disease.

In 2019, NOAA, which has authority over the protected waters inside the Florida Keys National Marine Sanctuary, launched Mission: Iconic Reefs, a 20-year plan to try to restore seven of the most notable reefs by growing and outplanting roughly 500,000 corals back onto them.

To accomplish this, NOAA is relying on several ocean nonprofits, such as Mote Marine Laboratory, Reef Renewal USA, and the Coral Restoration Foundation (CRF), as well as a large network of private aquariums. The CRF maintains large underwater nurseries where it grows critically endangered staghorn and elkhorn corals. Part of the researchers' work is selecting corals that are more resistant to heat and disease. Because coral can reproduce asexually as well as through sexual reproduction, hardy phenotypes can be split into fragments and regrown as identical clones.

Mote Marine Laboratory also recently started a breeding program to reintroduce the Caribbean king crab to the coral reefs. Animals like crabs and urchins are important grazer species that keep coral reefs from being smothered by fast-growing algae.

But when the heat wave hit the Keys this summer, staff had to frantically retrieve thousands of those coral samples and transport them to above-ground nurseries before they were cooked to death. One nursery near Looe Key was a total loss. The results could be equally dire for the over 100,000 coral fragments already planted back on the reefs.

If the reefs collapsed completely, it would be disastrous for the Florida Keys. According to the Florida Fish and Wildlife Conservation Commission, the reefs in Southeast Florida are valued at $8.5 billion and sustain 70,000 full- and part-time jobs. The barrier reef also protects the Keys from hurricanes and major storms by soaking up wave action.

But while the news is grim, it's also a testament to the ingenuity of the research groups and their passionate volunteers. Mote Marine Laboratory runs a volunteer-driven program called BleachWatch, where boaters and divers can submit bleaching reports and photos from their own observations of local reefs. This gives scientists an early warning system for bleaching in the Florida Keys.

Reason attended a volunteer orientation session for the BleachWatch program in August, followed by a dive with I.CARE, a local coral restoration nonprofit. I.CARE has an outplanting site that sits in deeper water than most, and the corals there were still thriving. Volunteer divers carefully scraped algae away from the tiny pieces of coral with steel brushes, giving them the best chance possible for survival.

When the water finally cools down, they will come back with more coral—and hope that future generations will be able to see a thriving reef.