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Ocean temperatures of 100 degrees has Florida battling a massive coral bleaching crisis

In the sweltering summer heat, an unprecedented and critical situation has emerged in Florida. The ocean temperatures have soared to a record-breaking 100 degrees Fahrenheit, instigating a mass coral bleaching event in the Florida Keys.

As the underwater heatwave continues, a desperate rescue operation is underway to prevent Florida’s coral species from slipping into extinction.

In just two weeks, bleaching has completely affected multiple coral reefs in the vicinity of the Florida Keys. Even worse, many have perished entirely, according to marine biologists. The rapid escalation of this calamity has shocked even the most seasoned experts. 

Grim forecast

The grim forecast for the near future predicts total extinction of the bleached reefs in a week if this oceanic inferno continues. The concerns extend even further to deeper reefs that could face a similar catastrophe if the ocean temperature continues to rise.

Excessive heat, compounded by an absence of rain and wind, has pushed the water temperatures around Florida to some of the most extreme levels ever recorded. 

A buoy located in the Florida Bay recently registered a staggering 101.1 degrees Fahrenheit at a depth of 5 feet. Although the area is known for its scant coral presence, researchers at other stations in the region have documented temperatures exceeding 96 degrees. One station even clocked a scorching 99 degrees, according to the National Data Buoy Center.

Corals are highly sensitive 

The severity of this heatwave is particularly destructive to coral reefs. Corals, by nature, are highly sensitive to temperature changes. 

An environment that remains excessively hot for an extended period can trigger a reaction in coral known as “bleaching.” Under such conditions, corals expel their algal food source, turn white, and gradually starve to death. 

This bleaching process is currently unfolding in the Florida Keys where the water temperatures have exceeded 90 degrees, far beyond the usual mid-80s that these marine ecosystems are accustomed to.

Florida coral bleaching and mortality

A striking illustration of this catastrophe is evident in a reef managed by The Florida Aquarium. On July 6, researchers recorded the water temperature at 91 degrees, and the coral was in perfect health.

A mere 13 days later, when the team returned, they found the coral entirely bleached, with an estimated 80% already dead.

The Coral Restoration Foundation reported a similar grim finding – “100% coral mortality” at Sombrero Reef off the coast of Marathon in the Florida Keys.

Keri O’Neal, the director and senior scientist at the Florida Aquarium told CNN: “This is akin to all of the trees in the rainforest dying. Corals serve that same fundamental role. Where do all of the other animals that rely on the rainforest go to live? This is the underwater version of the trees in the rainforest disappearing.”

Shocking images

Andrew Ibarra, a NOAA monitoring specialist at the Florida Keys National Marine Sanctuary, corroborated the extent of the destruction. Upon examining his “favorite reef,” Cheeca Rocks, he found the entire reef bleached. 

“Every single coral colony was exhibiting some form of paling, partial bleaching or full-out bleaching. Including recent mortality for some corals that have already died,” said Ibarra. CNN reports that Ibarra’s photos and videos “show a ghastly graveyard of corals.”

Katie Lesneski is the monitoring coordinator for NOAA’s Mission: Iconic Reefs. She told CNN: “The pictures are frankly horrifying. It’s hard for me to put into words how I’m feeling right now.” 

Despite the grim picture, Lesneski said there is still a “little hope spot” in a deeper reef where only 5 percent of the coral has begun to bleach due to slightly cooler water temperatures. However, even these corals are at risk if there’s no break from the relentless heat.

Florida coral bleaching is an escalating crisis 

The escalating crisis has sparked a desperate rescue mission. Reef restoration experts are now engaged in a delicate operation, extracting genetically significant species from their nurseries and moving them to land where they can escape the extreme ocean heat. 

These include corals like the Staghorn and Elkhorn, listed as “threatened” under the Endangered Species Act. Florida has already lost 90% of its Elkhorn coral, a species vital for reducing destructive waves from hurricanes.

The evacuated corals are now housed in water-filled, climate-controlled tables at facilities such as the Florida Institute of Oceanography’s Keys Marine Laboratory (KML). Thus far, KML has taken in at least 1,500 corals. They anticipate that the number will grow to 5,000 or more as the rescue mission unfolds.

Keeping species alive

“At this point we’re in emergency triage mode. Some of these corals that came in last week were looking very bad, and we may lose them,” Cynthia Lewis, director of KML, told CNN.

Despite these losses, every piece of coral saved can provide valuable insights into the survival of corals in warmer oceans. This will serve as a foundation for rebuilding Florida’s reefs post-bleaching event.

“If anything our work is more important than ever because we’re really depending on aquarium facilities to keep these species from going extinct in Florida,” said O’Neal. 

More about coral bleaching

Coral bleaching refers to the loss of color in corals. This occurs when stressors such as changes in light, nutrients, or temperature lead to the expulsion of symbiotic microorganisms from the coral’s tissues.

The phenomenon has serious implications for the health and survival of coral reefs. It often results in decreased growth and reproduction rates, increased susceptibility to disease, and, in severe cases, large-scale coral mortality.



Coral bleaching is primarily driven by changes in sea surface temperatures. Corals are sensitive to temperature changes, and even small increases can cause bleaching.

Warming ocean temperatures, attributed to climate change, are regarded as the most significant cause of recent and widespread coral bleaching events.


High-intensity light or changes in light spectrum can also induce coral bleaching, especially when combined with elevated sea temperatures.

Photosynthetic symbiotic organisms within the coral, called zooxanthellae, produce reactive oxygen species under intense light conditions. This can damage both the zooxanthellae and the coral tissues.

Other stressors

In addition to temperature and light, other environmental stressors can contribute to coral bleaching.

These include changes in salinity, nutrient availability, and water quality, as well as the presence of pollutants and diseases. Each of these factors can lead to physiological stress in corals, triggering bleaching.



Coral bleaching has significant ecological impacts. Coral reefs, often dubbed the “rainforests of the sea,” are biodiversity hotspots. They provide habitat and food for a myriad of marine species.

When coral bleaching occurs, as with the current Florida coral bleaching event, the loss of live coral cover can lead to the decline of these species and disrupt the intricate food web within the reef ecosystem.


The bleaching of coral reefs also has profound economic consequences. Many coastal communities rely on coral reefs for their livelihood, particularly through fisheries and tourism.

A loss of live coral cover can lead to a decline in fish stocks and a reduction in the appeal of diving and snorkeling sites. This significantly impacts local economies.

Mitigation and Conservation Efforts

Monitoring and research

Monitoring and research play a crucial role in mitigating coral bleaching. Scientists use various techniques, including remote sensing, to track changes in sea surface temperature and predict potential bleaching events.

Research is also underway to understand the genetic and physiological attributes that make some corals more resilient to bleaching than others.

Reducing local stressors

Management strategies aim to reduce local stressors on coral reefs. These include managing pollution, overfishing, and physical damage to reefs, all of which can make corals more susceptible to bleaching.

Coral restoration and assisted evolution

Coral restoration efforts involve the cultivation of corals in nurseries and their subsequent transplantation to degraded reefs.

More innovative techniques include “assisted evolution,” where corals are selectively bred or genetically modified to enhance their resilience to bleaching.

Mitigating climate change

As the primary cause of coral bleaching is warming ocean temperatures, reducing global greenhouse gas emissions is vital to mitigate coral bleaching. International agreements, such as the Paris Agreement, aim to limit global warming. This, in turn, would protect coral reefs from severe bleaching events.

In summary, coral bleaching is a significant global environmental issue that threatens the biodiversity, ecological function, and economic value of coral reefs.

While mitigation and conservation efforts are underway, the success of these strategies will depend largely on the extent to which global greenhouse gas emissions can be reduced to limit warming ocean temperatures.


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