Evaluating the Impact of Hurricane Dorian on our Coral Reefs

While it may have faded from the news, Hurricane Dorian continues to have a major impact on The Bahamas. The Perry Institute for Marine Science led the first expedition to assess damage to reefs throughout the northern Bahamas in October 2019. We are still analyzing data to measure the hurricane’s impact, but our preliminary data indicates that the effects of the storm varied considerably across Abaco and Grand Bahama. Despite the size, strength and duration of the storm, most reefs surveyed suffered little damage and may recover with little lasting impacts.

Some of the reefs hit hardest by the storm were in areas close to shore, where debris from land, ranging from destroyed homes to trees from shore smashed into them. In these areas, coral heads ranging from the size of a grapefruit to the size of a small car were toppled and rolled up to 50 meters from the reef. In several areas, mud from inshore smothered corals and buried reef stricture to nearly 3 feet.

The sheer power of Hurricane Dorian’s breaking waves damaged branching corals on some reefs, dislodged coral heads, and even caused large sections of reefs to calve off the way an iceberg breaks off a glacier.

Declines in coral health and fish populations were also noted on many reefs, but the level of damage varied significantly. While one reef may be nearly destroyed, another mere miles away was relatively unharmed. It is not a surprise that one of the sites that received the greatest damage was a shallow reef off of the Marsh Harbour coast. However, it was surprising that the damage to other nearby reefs was barely noticeable.

Other areas where damage was particularly bad included reefs in east Grand Bahama near the Equinor facility. Non-native trees from shore steamrolled across the reef, taking out everything in their path—even a half mile off-shore.  Reefs north of West End, Grand Bahama and the Abacos, between Spanish Cay and Grand Cay, also suffered extensive damage. Those areas were buried under layers of silt and mud.

With this initial assessment of reefs as a guide, we are planning to move forward with the Bahamian government and Bahamas National Trust to do more focused assessments of key areas and develop strategies to promote the recovery of these reefs.  We are also turning our attention to seagrass and mangrove habitats that may have also suffered extensive structural damage. We are especially interested in assessing the state and populations of key species in these areas, including queen conch, lobster and various fish.

Finally, as reconstruction efforts on land have begun, we have been working with local partners to help them recover and promote the development of a sustainable blue economy in the area. We are currently working to help provide economic opportunities to local fishers and dive operators whose homes and livelihoods were destroyed by Dorian. We are actively involving them in our research, conservation and restoration efforts. We are also working with them to rebuild infrastructure damaged by Hurricane Dorian, so that new economic opportunities can be created to replace those that have been lost.

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