Global coral bleaching could land heavy blow on Florida’s recovering reefs

Scientists fear a global bleaching event that has now become the largest on record could hit Florida’s 220-mile reef tract, the nation’s only shallow inshore reef.
Scientists fear a global bleaching event that has now become the largest on record could hit Florida’s 220-mile reef tract, the nation’s only shallow inshore reef. Florida Keys National Marine Sanctuary

A global coral bleaching that now ranks as the largest and longest on record could count Florida reefs among its next victims, scientists warned this week.

As a powerful El Niño in the Pacific fizzles, scientists say they are keeping a close on the 220-mile reef tract that stretches between the Dry Tortugas and Fort Pierce, where recent bleaching has claimed less than one percent of the reef. After the last major El Niño in 1998, the region lost about 30 percent of the reef, a mortality rate that could climb higher in the face of climate change and increasing ocean temperatures.

“If you think of corals as a canary, they’re chirping really loud right now, the ones that are alive,” said Jennifer Koss, the National Oceanic and Atmospheric Administration’s Coral Reef Conservation Program director. “We can’t afford to not listen to them.”

The planet is now in the midst of the biggest bleaching event ever documented, which has raised alarms about an ecosystem that globally acts an economic engine for some countries, the NOAA scientests announced Monday at a Honolulu conference. Reefs also serve as a first line of defense against tsunamis, fierce winter storms and, in Florida in particular, hurricanes.

Over the last two years, Florida’s reef tract has suffered some bleaching and disease outbreaks, but so far little of the reef died, said Billy Causey, NOAA’s Gulf of Mexico and Caribbean regional director at the Office of National Marine Sanctuaries.

The tract has also appeared to stabilize after the 1998 bleaching, with just a few ups and downs including a 2010 record freeze that killed some inshore reefs. But the forecast for continued bleaching through 2017 is cause for concern, he said. That’s partly because Florida reefs lack the diversity of species that make up other reefs, making them more vulnerable. Florida also sits at a crossroads for the Gulf of Mexico and Caribbean in relatively small basins where water quality can be poor. In the past, he said, Florida conditions often served as a first warning for events around the planet.

“It seems like we were at ground zero in Florida,” he said.

Globally, scientists fear that as the two-year bleaching continues, reefs already hit will suffer a second blow. Bleaching occurs when high water temperatures or pollution cause coral to expel the algae inside them that provide food and give them their color. Without a source of food, the coral weaken and become more susceptible to disease.

In 2013, a massive heat wave scientists dubbed the Blob hit the northeast Pacific, followed in 2015 by the El Niño that has resulted in about two years of continuous waves of warm water, said Mark Eakin, NOAA’s Coral Reef Watch coordinator.

“The warming in the Pacific has already put in place a warming pattern downstream in the Caribbean area,” he said. “That’s why we have so much concern in the Caribbean.”

Monitoring programs established following the 1998 event will help scientists track conditions and watch for bleaching, Causey said. If needed, managers may need to close areas to protect them. Causey is also hopeful some reefs will acclimate to new conditions or more resilient corals will emerge.

“What I’m seeing personally is that areas that bleach, one coral head is totally bleached and next to it not touched at all,” he said. “There are reefs out there that will be more resilient in the future.”

Follow Jenny Staletovich on Twitter @jenstaletovich