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Florida’s corals rescued from one of the worst bleaching events are back to the ocean

Temperature-controlled seawater systems at Keys Marine Laboratory (Florida Institute of Oceanography/WUFT News)
Temperature-controlled seawater systems at Keys Marine Laboratory (Florida Institute of Oceanography/WUFT News)

When the potentially record-high heat wave swept Florida in July, thousands of corals were rescued and relocated to land-based facilities to avoid bleaching. Now as the temperature drops to normal levels, healthy corals are ready to go back to their offshore nurseries.

Bleaching may be deadly for corals. When water temperatures swing to extremes, corals expel the algae in their tissues, turning them stark white.

“Saving our reefs is a community effort,” said Phanor Montoya-Maya, reef restoration program manager of the Coral Restoration Foundation in a press release. “And this was never more apparent than this summer when our network pulled together during one of the most extreme environmental challenges many of us have ever faced.”

Keys Marine Laboratory (KML), operated by the Florida Institute of Oceanography (FIO) at Long Key, sheltered more than 5,000 corals for approximately four months.

The urgency arose in July when coral restoration practitioners, including representatives from the Florida Keys National Marine Sanctuary and the Florida Fish and Wildlife Conservation Commission, requested assistance to save corals from bleaching caused by an unprecedented heat wave.

The restoration team commenced its month-long program on Oct. 30, successfully reintroducing about 360 corals to their offshore nursery at Tavernier on the first day. The plan is to return all rescued corals to nurseries by December.

The restoration process involves various partners, including The Florida Aquarium, the Florida Keys National Marine Sanctuary, Florida Fish and Wildlife Conservation Commission and the Coral Restoration Foundation.

According to Nicole Charnock, a biological scientist at KML, every coral that’s going back out into the ocean must get a coral veterinarian health check. But now, only one veterinarian is working on the certification process.

“It’s a pretty rigorous process,” said Charnock. “They’re a little bit limited on how quickly they can put things out. They’re making sure that every single coral is healthy and ready for that move.”

While many healthy corals are waiting for relocation, researchers capitalize on the time by proactively advancing their work.

They employ a technique called micro fragmentation, breaking healthy corals into smaller pieces of 1 to 5 polyps with specialized saws. This process stimulates coral tissue growth, enabling them to grow into clones at an accelerated rate, 25 to 50 times faster than normal.

“The idea behind it is similar to if you cut your hand and your skin tries to grow back really fast over that wound,” Charnock said.

Coral reefs are often called the “rainforests of the sea.” They sustain habitats for marine life, buffer the impacts of storms on coastal communities and support local economies.

Since April 2023, the National Oceanic and Atmospheric Administration (NOAA) has been monitoring a steady rise in ocean temperatures. Record-breaking warm ocean temperatures have bleached and killed corals within 3,800 square miles of the Florida Keys National Marine Sanctuary.

In July, a sensor in Manatee Bay near Everglades National Park recorded 101.1 degrees Fahrenheit, potentially a world record.

Joshua Patterson, associate professor of restoration aquaculture at the School of Forest, Fisheries and Geomatics Sciences at the University of Florida, said the bleaching issue is not new to Florida. But this summer, the heat was particularly early and more extreme than what has been recorded.

“This is the first summer that I can remember where it’s turned into an active rescue effort if you would say,” he said. “In the past, it’s been more of a monitoring type response, just documenting things and doing research to look for what survives in the thermally tolerant colonies.”

KML, one of the largest temperature-controlled seawater systems in the Florida Keys, took measures to combat the bleaching crisis – it has tripled the number of pumps to 120 and installed 60 water tanks ranging from 40 to 1,000 gallons.

However, the extreme climate pattern poses a looming threat to Florida Keys corals next year. Patterson said that moving corals back and forth to the ocean may not be a viable solution for the next summer.

Removing a coral from the ocean and bringing it into a land-based system carries risks. Corals that don't respond well to transportation may perish. And there's a biosecurity concern where unwanted elements could be inadvertently introduced or released.

In Florida, practitioners follow stringent inspection guidelines to make sure corals are inspected before they return to the ocean.

“A fair number” of organizations are working on preserving genetic representatives, Patterson said. Pillar coral, a species with only a handful of natural colonies in Florida, is safeguarded in large numbers in land-based systems.

The Florida Aquarium is also focusing on spawning corals they have in land-based systems in the hope of increasing genetic diversity and identifying corals that are thermally tolerant.

“Potentially we can learn more about these corals and identify ones that are more thermally tolerant or resistant to disease,” he said. “Although there is still a lot to be worked out there.”

Haohong is a reporter for WUFT News who can be reached by calling 352-392-6397 or emailing news@wuft.org.