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Hurricane Irma Changes the Seascape in the Florida Keys

Hurricane Irma has changed the underwater landscape of the Florida Keys. But the reef ecosystem is beginning to recover — with a little help.

Divers returning to the Florida Keys will notice changes to the seascape following the tremendously strong waves and surge of Hurricane Irma. The Category 4 storm struck on September 10. The powerful storm sheared sponges, broke fragile corals, fractured the reef, and littered the sensitive environment with fishing traps, lines, nets and boat and household debris. While the lingering effects of churned-up fine sand and heavy sediment remain evident months after the hurricane, the powerful storm was not catastrophic. The reef ecosystem is beginning to recover – with a little help.

How did the reef fare?

A rapid assessment in mid-October of Florida Keys National Marine Sanctuary surveyed 57 high-priority sites. Note that this is a relatively small portion of the Florida Reef Tract, which stretches approximately 360 miles from Dry Tortugas National Park west of the Florida Keys to the St. Lucie Inlet in Martin County. It is the only living barrier reef in the continental United States.

Science divers documented broad-scale impact, noting that damage type and severity varied within regions and even within sites. The majority (53 percent) of the sanctuary’s reef suffered minor damage, but 33 percent of the surveyed areas had sustained moderate damage. Divers found severe impacts at 14 percent of the sites with those deemed as top priorities for emergency actions.

Where the hurricane’s eyewall crossed the Middle and Lower Keys, divers reported that the reef framework had fractured and eroded. Some areas here experienced blowouts. Ancient substrate is now exposed, offering divers a view of the reef’s building blocks through the ages.

Sections of the coral reef in the Florida Keys National Marine Sanctuary suffered fracturing and undermining. Credit: Steve Gittings/NOAA
Photo: Steve Gittings/NOAA

Sand and silt carried by fast-moving wave action damaged, sheared and choked sponges, causing widespread mortality. Heavy sedimentation and turbidity continue to slow recovery and exacerbate preexisting conditions, such as coral disease and bleaching. Marine debris — including an estimated 150,000 lobster traps — also poses a challenge for removal.

Reef recovery efforts

NOAA, with its partners, quickly embarked on focused triage. Divers worked to unbury, reposition and reattach corals where stabilization offered a greater chance for recovery. NOAA undertook this first-of-its-kind emergency response to a natural weather event due to the sheer size and force of Hurricane Irma. Florida’s coral reef tract, home to seven threatened species, is already under tremendous stress from bleaching, disease, ocean acidification, climate change and sea-level rise.

The massive, coordinated assessment and response effort included not only the Florida Keys National Marine Sanctuary, but many other government agencies and stakeholders, including the Office of National Marine Sanctuaries and the National Park Service.

NOAA will continue to work with restoration partners on short- and long-range efforts. These will include include sanctuary-permitted, manmade nurseries where more resilient coral types are grown for transplantation. Nurseries directly in the storm’s path suffered 95 percent loss, while those outside the eyewall remained mostly intact.

How can you help?

Visitors to Florida Keys National Marine Sanctuary can help monitor ocean conditions by reporting what they see, including the locations of marine debris, coral disease and invasive species such as lionfish. The sanctuary partners with Mote Marine Laboratory and Aquarium using the Community-based Observations of Coastal Ecosystems and Assessment Network (C-OCEAN). The online reporting tool can provide early detection and assessment to help the scientific community better understand events — both natural and human related — that adversely affect marine organisms. There is no paperwork involved and you won’t need specialized training.

If you’re planning a visit, the Florida Keys National Marine Sanctuary features several Blue Star dive operators. These centers take extra step to help divers become better environmental stewards and to interact responsibly with coral reefs.

By guest authors Gena Parsons and Marlies Tumolo, NOAA

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