A new study that shows coral bleaching events will become more prevalent and severe in the next 15 years is underscoring the importance of the restoration work pioneered by Florida Keys researchers.
Those Keys scientists have already begun to grow bleach-resistant genetic strains of coral.
Whether it's fishing, diving or tourism in general, coral reef and seagrass ecosystems are the engine that drive the Florida Keys economy. Florida Keys' reefs and seagrass meadows are responsible for 33,000 jobs and $2.3 billion a year in revenues, according to an economic study by National Ocean and Atmospheric Administration (NOAA).
However, a recent study by NOAA scientists paints a bleak future for coral reefs when it comes to coral bleaching in South Florida and the Caribbean.
"Coral bleaching events are expected to increase in frequency and severity as the climate changes," the study stated.
Extremely warm water temperatures can result in coral bleaching. When water is too warm, corals will expel the algae, called zooxanthellae, living in their tissues, causing the coral to turn completely white. Corals can survive a bleaching, but they are under more stress and are subject to mortality and disease.
However, not all bleaching is tied to warm-water events. In January 2010, cold water temperatures in the Florida Keys caused a coral bleaching that resulted in some coral death.
Light bleaching occurs by the end of most every summer in the Keys and the Dry Tortugas, but extreme bleaching, which in some cases lead to coral death, occurs every five to 10 years. Ruben van Hooidonk, a University of Miami coral researcher and NOAA climate scientist, found that extreme fatal bleaching could occur every year starting 2030 or 2035, he said.
"It's urgent that we reduce our green house gas emissions, not only in the U.S. but globally," van Hooidonk said.
But extreme temperatures are not the only stress on the reef, van Hooidonk said. Run-off and other land-based forms pollution, anchoring on the reef and use in general are also impacting the reef, van Hooidonk said.
"These are all preventable things," van Hooidonk said.
Groups like the Tavernier-based Coral Restoration Foundation, Summerland Key-based Mote Marine Laboratory and The Nature Conservancy are coming to the rescue of Keys' reefs. Those groups have been growing corals in their nurseries and replanting them on the reef for more than a decade. The groups have identified certain specific genotypes that are more resistant to extreme temperature changes in coral.
The Coral Restoration Foundation has reared more than 150 different genetic strains staghorn coral and 60 strains of elkhorn coral.
"It's important to have different genetic strains of corals," Coral Restoration Foundation founder Ken Nedimyer said. "Some might be heat resistant and not be cold resistant or vice versa. We are focusing on the bleach resistant ones. You can focus on the bad or focus on finding solutions."
Mote has grown 55 different strains of coral, said Dave Vaughan, who oversees Mote's tropical research center on Summerland Key.
"Some had no bleaching," Vaughan said. "Some survived well and others bounced back."
Mote recently obtained a $250,000 grant from the National Science Foundation to construct a series of large tanks that will allow Mote to expose different strains of coral to different temperatures and pH levels to determine which corals do well with the added stress, Vaughan said.
"It is important to have this healthy stock of genetically diverse corals," van Hooidonk said. "This study could also show possible locations for other nurseries and out-planting sites."
In 2005, Mote partnered with the Florida Keys National Marine Sanctuary on a program called "Bleach Watch." Mote officials train recreational, commercial and scientific divers to monitor and report on conditions at the reefs. Each diver is provided with a water-resistant identification card or wristband showing different types of coral and how to document percentage of living coral to bleaching. A diver who completes a dive will fill out a data form and send it to the Bleach Watch coordinator.
A condition report is available online and updated monthly, weekly or biweekly, depending on the severity of climate conditions, Walter said.