Author: Bryn Nelson / Source: Science News for Students
PLAYA LARGA, Cuba — The Bay of Pigs is surprisingly clear and vividly blue — nothing like its name might suggest.
Cuba’s famous bay looks like an artist’s palette — one that stretches toward the horizon. There’s a streak of robin’s-egg blue by the rocky shore. Further out, the water turns turquoise, then navy blue where the seafloor drops down to meet the deeper ocean.Beneath the surface, bright bursts of other colors come into view. Even in 10 meters (about 33 feet) of water, you can see hills on the sandy bottom. Look closer and you can see that each hill is a clump of fanciful structures in greens, browns, oranges and purples. They resemble piles of boulders topped by tubes, antlers, bushes and fans. They’re coral reefs, or stony ridges made from the external skeletons of millions of tiny marine creatures living together. Fittingly, some scientists call them “animal forests.”
Many of these animal forests around the world are in big trouble. People have harmed some by carelessly climbing on the corals or by catching too many of the fish that keep reefs healthy. Diseases, global warming and fierce storms have battered other reefs. Scientists are especially worried about Australia’s Great Barrier Reef. Unusually warm water there in 2016 killed large sections of the connected corals.
Recent research suggests that pollution and warmer waters have raised the risk of mass die-offs in other tropical reefs. Such threats can leave huge dead zones in the water and turn corals a ghostly white. One recent study found that corals off the coast of Panama had been badly damaged within the past decade.
Other researchers have been noting more gradual changes that have taken place over centuries. To do this, they pored over old sailing charts. These charts had warned sailors about the locations of reefs to help prevent shipwrecks.
Looking at those charts now suggests that the island chain making up the Florida Keys has lost more than half of its corals during the past 240 years. Reefs closest to shore have suffered most.
Most Cuban corals have avoided the same fate. Scientists now want to know why.
Some reefs near Cuba’s coast, like those in the Bay of Pigs, have lost large predators, such as sharks and sea turtles. Even so, they still support communities teeming with colorful medium-sized and smaller fish. Coral hills, called patch reefs, grow closer together. They can rise up to become low mountains. Then they disappear into deepest blue down the ledge.
The United States and Cuba have a troubled past that can be traced in part to this very bay on the island’s southern coast. And their prickly relationship has often made it hard for the two countries’ scientists to work together.
In 1961, about 1,400 exiled Cuban soldiers returned to the Bay of Pigs and tried to invade the country. With support from the United States, they tried to overthrow a new ruler named Fidel Castro. He was a rebel who had seized power and was setting up a form of government known as communism.
The invasion failed. Castro stayed in power. And the United States and Cuba have been at odds ever since.
Relations between the two countries have warmed a bit over the past few years. Despite ongoing disagreements and travel restrictions, Cuba’s wide variety of unique wildlife is drawing more U.S. scientists and tourists. The World Wildlife Fund has called this nation“by far the most biologically rich and diverse island in the Caribbean.” Researchers from both countries now are teaming up on new projects. And they’re calling for more cooperation to help Cuba preserve its unusually healthy corals.
By working together, the researchers hope to shed new light on important species that live on or near the reefs. What they learn could help scientists protect other ocean animals around the world.
Doing the time warp
Compared to coral reefs elsewhere in the Caribbean Sea, many of Cuba’s are “quite stunning,” says Daria Siciliano. She’s a coral expert at the University of California, Santa Cruz. These reefs, she says, host more species and in greater numbers. They also are virtually undisturbed by humans.
“In Cuba, you can very much see some of the coral reefs that you would have seen 50 years ago elsewhere,” Siciliano says. “So it’s a time warp.”
Coral reefs do better when they have plenty of fish in all sizes. Cuba’s reefs have fared well because many still have small and large species that other places have lost.
Dan Whittle directs the Cuba Program at the nonprofit Environmental Defense Fund in Washington, D.C. He explains that larger animals, such as sharks and other big fish, eat smaller ones. This helps maintain a healthy balance between predators and prey.
The reefs, in turn, are a key link in a chain of connected habitats that includes coastal swamps and the deeper ocean. Neighboring the Bay of Pigs is Cuba’s Zapata Swamp. Some biologists consider it the most important wetland in the Caribbean. Eighty percent of Cuba’s species can be found here, including the critically endangered Cuban crocodile.
To the east, scuba divers and researchers love exploring another underwater wonderland. It’s called Gardens of the Queen National Park and is about 90 kilometers (56 miles) off of Cuba’s southeastern shore. Coral reefs there are so pristine that some visitors have nicknamed it “The Crown Jewel of the Caribbean.”
One potential reason for the Cuban reefs’ good health is that the country has less pollution than in neighboring countries. Cuban farmers use fewer chemicals on their fields that can wash into the ocean when it rains. Cuba also hasn’t built as many homes and businesses along its coastline as many other nations have. In all, the country has banned fishing in about 23 percent of the shallow ocean waters surrounding the island. That ban helps protect fish of all sizes. It also keeps the number of predators and prey in balance. About 3 percent of U.S. waters are in comparable protected zones.
Cuba’s conservation record isn’t perfect. And plenty of challenges remain. Enforcing rules to protect the…
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