Researchers assess damage to coral reefs in Florida Keys after historic marine heat wave

Feb. 15 (UPI) -- A team of researchers completed a scientific mission Wednesday to assess the damage from last year's record-high marine temperatures on restored coral reefs in the Florida Keys.

The National Oceanic and Atmospheric Administration's Mission: Iconic Reefs program released the findings Thursday, which focused on 64 locations at five reef sites: Carysfort Reef, Horseshoe Reef, Sombrero Reef, Looe Key Reef and Eastern Dry Rocks.

Mission: Iconic Reefs conducted the research with Mote Marine Laboratory & Aquarium and the Coral Restoration Foundation.

The investigation focused reef-building stony corals that were nursery-raised and transplanted by the Coral Restoration Foundation, Mote Marine Laboratory & Aquarium and Reef Renewal.

Preliminary findings indicated less than 22% of approximately 1,500 staghorn coral surveyed remain alive. Only the two northernmost reefs surveyed, Carysfort Reef and Horseshoe Reef, had any living staghorn coral.

Of the five reefs surveyed, only Carysfort Reef, Sombrero Reef in the middle Keys and Eastern Dry Rocks off Key West had any living elkhorn coral.

Researchers found no live staghorn or elkhorn coral in Looe Key Reef in the lower Florida Keys.

Rough weather conditions prevented the research team from surveying more than the branching staghorn and elkhorn coral transplants, but Mission: Iconic Reefs said anecdotal evidence suggests boulder, massive and brain coral transplants fared better during the marine heat wave.

"The findings from this assessment are critical to understanding the impacts to corals throughout the Florida Keys following the unprecedented marine heat wave," said Sarah Fangman, Florida Keys National Marine Sanctuary superintendent. "They also offer a glimpse into coral's future in a warming world."

Corals in the Florida Keys faced the hottest ocean temperatures on record last summer. It also was the longest-lasting recorded marine heat wave in 30 years, according to NOAA.

The unprecedented high temperatures prompted evacuation of in-water nursery corals to land-based nurseries to limit their exposure to the heat.

The health of Florida's coral reefs has declined since the 1970s, according to NOAA. Contributing factors include damage from hurricanes, heat-induced bleaching, disease and human impact.

NOAA said Thursday's report will support Mission: Iconic Reefs' efforts to restore nearly 3 million square feet of coral reef at seven sites in the Florida Keys National Marine Sanctuary.