KEY LARGO, Fla. -- Dive operations in the Florida Keys are up and running in the aftermath of Hurricane Irma, but divers will find an altered reef system.
"The reefs took a hit during the storm," said Martha Roesler, chief development officer for the Key Largo-based Coral Restoration Foundation, whose mission is to restore the Florida reef tract.
From Oct. 9 to 19, the Florida Keys National Marine Sanctuary, which encompasses 3,840 square miles around the Keys, conducted a preliminary assessment of 60 reef sites. Of those, regional research associate Lauri MacLaughlin said, 14% were categorized as Tier 1, meaning that they were in especially dire need of restoration. Conversely, 53% of the sites were placed in the least dire category of Tier 3.
At some sites, the reef itself had structural damage, as did individual corals and sea fans. A layer of sediment -- sometimes thin, sometimes several inches thick -- has also formed on many reefs. The sediment is having an especially strong impact on the sponge population, said marine sanctuary chief of staff Mike Bachman, because it clogs up the sponges' pores and prevents them from eating.
But both MacLaughlin and Roesler said that fish populations along the reefs appear to be especially abundant, likely due at least in part to the fact that few people have been fishing sanctuary waters since Irma.
Divers headed to the Keys can expect to see the most damage to reefs located closest to the center of Irma's path, sanctuary officials said.
For example, the popular Looe Key Reef just offshore of the Lower Keys, where Irma was centered, was hard hit, said MacLaughlin, who has assessed the site personally. Likewise, Sombrero, about 20 miles to Looe's northeast and the best known reef in the Marathon area, also sustained enough toppled corals to be designated as Tier 1.
Oft-frequented reefs off of Key West, such as Sand Key and Western Dry Rock, fared better, said Bachman, who has dived those sites post-Irma.
"What I've noticed is kind of a range of conditions, which is what we sort of expected," he said.
Similarly, conditions off Key Largo and the Upper Keys, which have the region's highest concentration of dive sites, vary. Molasses Reef, believed by some to be the most spectacular in Florida, weathered the storm without major damage, said Bill Goodwin, a resource manager of the marine sanctuary.
Horseshoe Reef, home to the Keys' largest remaining stand of endangered elkhorn coral, had entire colonies toppled over.
Popular wreck sites off the Keys generally withstood Irma, though some sustained damage.
The 522-foot Gen. Hoyt S. Vandenberg off of Key West was turned approximately 35 degrees by the storm's wave action, Bachman said, but is in good shape. A portion of the 310-foot Coast Guard cutter the Duane, which sits off Key Largo, broke and is lying in the sand, MacLaughlin said.
Despite what damage there is along the Upper Keys' reefs, guide Ryan Jenkins of Rainbow Reef Dive Center in Key Largo said that businesses has been strong of late on weekends.
"The reefs fared pretty well," he said.
Jenkins said that visibility off the Upper Keys has returned to normal. Still, Mac-Laughlin cautioned that especially from the Marathon area south to Key West, conditions could be more silty than normal for as long as a year, as sediments that were pushed west by Irma from the Atlantic Ocean to the Gulf of Mexico and Florida Bay slowly filter back downstream.
Meanwhile, Roesler said, the damage that Irma caused to the reefs means there will be plenty of opportunity for civic-minded divers to combine a Florida Keys visit with volunteer work at the Coral Restoration Foundation nursery sites.
"We have the opportunity to help bring back a healthy reef," she said.