The Gulf of Mexico is known for its oil, but it's also home to the unexpected. About 240 miles from Houston and surrounded by offshore oil platforms lies Flower Garden Banks National Marine Sanctuary, one of the world's healthiest coral reefs.
Marine researchers who have visited Flower Garden Banks describe it with awe in their voices. „When you look out there, there's so much coral that it can be disorienting,“ said Michelle Johnston, superintendent of Flower Garden Banks National Marine Sanctuary.
Like coral reefs around the world Bleaches at an amazing rate, scientists are racing to study and preserve this amazing coral reef in unlikely places. „We have this magical underwater place, (and) it's completely surrounded by the oil and gas industry,“ Johnston said.
![Underwater panoramic photo of healthy coral covering a coral reef](https://grist.org/wp-content/uploads/2024/05/NOAAHickerson.jpg?quality=75&strip=all)
![Underwater panoramic photo of healthy coral covering a coral reef](https://grist.org/wp-content/uploads/2024/05/NOAAHickerson.jpg?quality=75&strip=all)
Emma Hickerson/Flower Garden Banks National Marine Sanctuary (via NOAA)
To understand how both can exist in such close proximity, it helps to understand the history of the area. About 190 million years ago, the oceans here dried up, leaving behind huge salt flats. Over many years, the dried salt layer was buried deep underground.
Eventually, a new body of water formed above it, the Gulf of Mexico. Because the salt is less dense than the surrounding rock, its layer slowly rose toward the surface, pushing the earth above it and at the same time pulling up large oil deposits from below. This change slowly led to the formation of giant underwater mountain ranges known as „salt domes.“ If you look at a map of the Gulf of Mexico today, you'll see that many of the oil extraction sites are on the same ocean floor mountains.
Some of these mountains were so high that sunlight only reached them through the water. Then, about 10,000 years ago, coral polyps began to twine around the top and grow. Those underwater peaks are now Flower Garden Banks.
Because coral reefs are far from the coast, they have been protected from many threats, such as overfishing and coastal pollution. And thanks to its depth and northern latitude, the water here is cool enough for corals to tolerate, essentially protecting Flower Garden Banks from global warming. For example, in the summer of 2023, while other coral reefs in the Caribbean were devastated by heat stress and bleaching, Flower Gardens' unique geology helped it manage to survive better than others.
But this same unique geology also made the region a major hub for offshore oil drilling.
“When you’re offshore diving in Flower Gardens, you look around from the dive boat and you see oil and gas platforms in every direction,” Johnston said. “So everything in this industry is happening around this beautiful place.”
![floating oil drilling platform](https://grist.org/wp-content/uploads/2024/05/AP23320772290156.jpg?quality=75&strip=all)
![floating oil drilling platform](https://grist.org/wp-content/uploads/2024/05/AP23320772290156.jpg?quality=75&strip=all)
LM Otero/AP Photo
So far, coral reefs have thankfully avoided catastrophic oil spills, but that doesn't mean oil hasn't left its mark. In fact, the legacies of oil extraction, carbon emissions, and climate change are literally etched into the hard skeleton of corals themselves.
„I think of that skeletal material as a little time capsule,“ said Amy Wagner, a scientist who studies corals for clues about Earth's past.
In 2005, when she was a graduate student, Wagner and a team of scientists visited Flower Garden Banks in search of a very special type of coral, Siderastrea siderae. “It looks like a chunk of stone at the bottom,” she said.
The team dived 78 feet to the top of these ancient mountain peaks and excavated an approximately 6-foot core of this slow-growing species of coral. This is his 250 year record of pollution, climate change and even world events. „When you start drilling, especially the first time, you get a layer of coral tissue,“ Wagner says. “So, since it’s free food, a lot of fish end up coming in, right?”
![A diver holds a digging tool near a rock-shaped coral.](https://grist.org/wp-content/uploads/2024/05/Wagner1.png?quality=75&strip=all)
![A diver holds a digging tool near a rock-shaped coral.](https://grist.org/wp-content/uploads/2024/05/Wagner1.png?quality=75&strip=all)
![hole in coral](https://grist.org/wp-content/uploads/2024/05/Wagner2.png?quality=75&strip=all)
![hole in coral](https://grist.org/wp-content/uploads/2024/05/Wagner2.png?quality=75&strip=all)
Amy Wagner's team excavated coral samples from Flower Garden Banks in 2005. Courtesy of Amy Wagner and John Halas
After hours of digging, they repaired the hole and swam the 6-foot-long core to the surface. Back at the lab, they cracked open the core sample and took X-rays. “They’re like trees,” Wagner said. „You can count tree rings and go back in time. Corals produce annual bands like this.“
Living coral organisms use nutrients and minerals drawn from seawater to build new growth zones each year. Basically, everything that's in the seawater goes into the skeletal layers of corals that year. „So we have a long record of tiny little time capsules that contain ocean chemicals,“ Wagner said.
Wagner and colleague Christine DeLong, a professor at Louisiana State University, used a high-tech version of a dental drill to collect tiny amounts of dust from each growth zone. Then, like detectives, they analyzed various elements in the dust for clues and studied how the coral's core changed over time.
![The person holds a white stick split in half with a band along the inside long notch.](https://grist.org/wp-content/uploads/2024/05/Wagner-Core.jpg?quality=75&strip=all)
![The person holds a white stick split in half with a band along the inside long notch.](https://grist.org/wp-content/uploads/2024/05/Wagner-Core.jpg?quality=75&strip=all)
Jesse Nichols / Grist
Just like humans, corals build their skeletons from calcium. However, sometimes we make mistakes and accidentally extract similar elements from seawater. One of those elements is barium, which is often used as a lubricant in offshore oil wells. During the energy crisis of the 1970s, oil drilling boomed in the Gulf of Mexico. Wagner and DeLong were then able to see that spike reflected in barium concentrations within the coral. When oil prices collapsed, production decreased and so did Valium.
There's a lot of other history that scientists can see etched into this coral's core. When we look at nitrogen, we see that fertilizer pollution from the Mississippi River is increasing. Radiocarbon tests show that nuclear weapons testing increased during the Cold War.
And corals even tell the story of how fossil fuels are changing the climate. In the words of one scientist, they are „recording the coral's own demise.“ To understand that, it's important to know that carbon atoms are not all exactly the same. There are actually several different weights, depending on the number of neutrons on each carbon atom. Carbon atoms with seven neutrons are called „heavy carbons“ and atoms with six neutrons are called „light carbons.“ Plants prefer to use light carbon for photosynthesis. Therefore, carbon atoms inside plants tend to be slightly lighter than carbon atoms inside volcanoes, for example.
Fossil fuels are derived from ancient plants that are light and carbon-rich. As fossil fuel emissions increase, carbon atoms in the atmosphere become progressively lighter.
![](https://grist.org/wp-content/uploads/2024/05/Xray.jpg?quality=75&strip=all)
![](https://grist.org/wp-content/uploads/2024/05/Xray.jpg?quality=75&strip=all)
Provided by Christine DeLong
We can see this same trend occurring inside the coral. As the world burns more fossil fuels, coral carbon slowly becomes lighter in band samples. As the climate warms due to these fossil fuel emissions, coral reefs around the world are at risk.
Today, Flower Garden Banks is still holding out, but it won't be safe forever. As early as 2040, Flower Garden Banks could begin to experience large-scale bleaching events every summer. If we were to reduce emissions at a more reasonable pace, climate models suggest we could buy another 15 to 20 years for our flower garden banks, effectively doubling that period. Become. That window is critical to the sanctuary's staff and independent scientists who work diligently to study and protect what may be one of the last remaining coral reefs.
„When you go to places like flower gardens, it's like this coral is still very healthy,“ DeLong said. „It's important to be able to manage and care for these reefs, because they could be the last reefs we have.“
Flower Garden Banks scientists recently began collecting corals from the reef and storing them in a land-based coral research laboratory. The hope is that there will eventually be enough coral stocked here in case the worst happens.
![A blue aquarium with round corals](https://grist.org/wp-content/uploads/2024/05/Tank.jpg?quality=75&strip=all)
![A blue aquarium with round corals](https://grist.org/wp-content/uploads/2024/05/Tank.jpg?quality=75&strip=all)
Jesse Nichols / Grist
„It's a grim outlook,“ Johnston said. “It’s better to be proactive and save something than to end up in a situation where all the corals bleach and die and there’s nothing left. I hope we can adapt. I think the problem is that the climate is changing so quickly that we may not have time.“
The Flower Garden Bank is the product of 10,000 years of slow and steady growth, capturing an annual snapshot of our world in tiny millimeter-sized chapters. The next few decades will be crucial in determining how long this reef can continue its ancient underwater history.