The Florida Reef spans 358 miles from end-to-end and is almost 4 miles wide at its most dense. Its base is made up of slow-growth stony corals dating back 5,000 to 7,000 years.
It is one of the largest tropical reef systems in the world; only Australia's Great Barrier Reef and the Meso-American Barrier Reef near Belize are larger. Home to at least 1,400 species of corals, invertebrates, mollusks, crustaceans, fishes and marine mammals, its rich biodiversity supports the health of millions of plants and animals that live within, on and around it—and the $7 billion diving, fishing and tourism-based economy of the Florida Keys.
The reef also protects the region around it, acting as a buffer against powerful storm surges for adjacent islands and beaches. Its health is so crucial to life in its region that it is illegal to remove corals from the reef or harm it in any way.
So, how did National Aquarium aquarists in Baltimore come to be in possession of 98 specimens of precious Florida corals?
Back in 2014, researchers from the Florida Keys National Marine Sanctuary noticed a sudden decline in the health of some species of stony corals that make up the structural base of the Florida Reef tract. Reef colonies began to develop irregular patches of exposed white coral skeleton, devoid of the colorful, live tissue typically associated with healthy reefs. Within weeks of detection, corals exhibiting tissue loss would perish completely.
The culprit is a pervasive outbreak of a pathogen now known as Stony Coral Tissue Loss Disease (SCTLD) which is transmitted by contact or water flow from one coral to the next. Its origin is still somewhat mysterious, but it is exacerbated by rising water temperatures and ocean acidification associated with climate change, as well as harmful nutrient runoff from human-driven activity on land. To date, 60% of corals within the range of the SCTLD outbreak are infected; all corals infected so far have died.
By 2017, faced with an expanding zone of infection and a ticking clock, researchers and regulators wisely expanded their focus beyond investigating the SCTLD outbreak in order to create a plan for future reef recovery.
Teams of divers began rescuing healthy coral specimens from waters beyond the disease front as the Florida Fish and Wildlife Conservation Commission (FWC), the National Oceanic and Atmospheric Administration (NOAA) and the Florida Keys National Marine Sanctuary began to contact peers and research partners—including universities, marine laboratories and AZA-accredited institutions like the National Aquarium—looking for assistance with housing, monitoring, protecting and, eventually, propagating healthy corals. Their hope is to not only protect healthy samples of corals impacted by SCTLD, but to someday be able to use these samples and their potential offspring to repopulate the reef.
Dozens of institutions responded. Some—like the National Aquarium—had available tank space and experts able to assist in structuring and guiding the project; others were able to contribute funds necessary to finance the work. As of October 2019, the Aquarium is one of more than 30 sites across the U.S. holding more than 1,500 healthy coral samples. While still the property of the FWC, the corals on loan to the Aquarium will spend at least three years in our Animal Care and Rescue Center as our treasured guests.
Corals are not plants; they are aquatic invertebrate animals related to anemones and jellies. In order to thrive, they require clean, warm circulating water, regular feeding and reliable exposure to light. That means each of the 98 corals currently in our care receives individual attention each day. Every coral is fed twice daily, receiving a steady diet of algae and microscopic animals known as zooplankton via turkey baster. Our team also looks for the appearance of new polyp-stage coral, measures colony growth and keeps a close eye on the presence and quantity of naturally occurring reef residents, including algae, crustaceans and other tiny plant and animal life, ensuring all relationships remain in balance—while also keeping an eye out for any health concerns that might arise.
Assuming the ACRC corals retain their health and vitality, project aquarists will eventually work to encourage coral reproduction several years from now. Regardless of species, successful replication will eventually be critical to the success of the SCTLD rescue project since substantial quantities of coral will be necessary to replace the thousands lost to SCTLD and save the Florida Reef.
Meanwhile, scientists in Florida continue to monitor water quality, looking for a specific event or trigger for this particularly lethal outbreak of SCTLD, and are investigating why some corals—like the already-endangered elkhorn and staghorn corals that form much of the reef’s mass—do not appear to be impacted by SCTLD. Learning what renders some corals immune to the disease could be a key to saving the reef from future disease events.
"For us, a successful outcome would be maintaining the biosecurity of these corals so that we can send them back to Florida where they can play a role in restoring the reef," says National Aquarium Assistant Curator Brian Nelson, who also serves as chair of the Association of Zoos and Aquariums (AZA) Aquatic Invertebrate Taxonomy Advisory Group. "We have to do whatever we can; we cannot someday look back and see that we had the opportunity to help save the reef and did nothing."