Elkhorn coral near St. Martin in the Caribbean Source: David Montalvo

Swim out into the turquoise waters of the Caribbean, just beyond where the sandy sea floor gives way to massive rock formations, and a decades-long transformation has become apparent. Where a vibrant coral reef should be, there is a vast, colorless surface of almost nothingness. Years of overfishing, boating and environmental degradation are causing coral reefs in the Caribbean—and around the world—to disappear in huge numbers. Indeed, the erosion threatens not just fish and marine life that are supported by coral ecosystems, but a vast tourism economy that the National Oceanic and Atmospheric Administration says translates into a nearly $30 billion boost to the global economy. The United Nations and conservation groups have sounded the alarm about the ecosystem's failure and its ripple effects, which include the mass extinction of thousands of species of animals. "Coral degradation is a global problem," said Luis Solorzano, executive director at The Nature Conservancy, a nonprofit organization working in more than 35 countries and operating more than 100 marine conservation projects. Read MoreThe Great Barrier reef could lose 90% of its coral "Coral reefs help protect coastlines, which include coastal communities, hotels and other investments, from storms," Solorzano said. In fact, the stony substance minimizes the force of sea waves and helps protect an estimated 200 million people in islands and coastal states from storms and rising sea levels, according to researchers at Stanford University.



The trouble with St. Martin

In the turquoise waters off St. Martin, just out of reach from the sandy beach, a towering elkhorn coral comes into sight. A few fish can be seen huddling around its shadow, darting into the dark at signs of danger. Private boats and Jet Skis are frequent visitors. The vibrant scene, teeming with life, belies the fact that St. Martin's shores are actually locked in a life or death struggle. In a study last year, Stanford scientists estimated that up to 60 percent of coral reefs around the world have been wiped out since the Industrial Revolution. Meanwhile, there are indications that things could be getting worse in the Caribbean, which recent studies have shown have lost 80 percent of their coral reefs. Read MoreThe popular fish that we may be making poisonous Local economies, noted the U.S. oceanic agency, "receive billions of dollars from visitors to reefs through diving tours, recreational fishing trips, hotels, restaurants, and other businesses based near reef ecosystems." St. Martin is an island a third the size of Washington, D.C., and about 200 miles east of Puerto Rico. In the 1960s, it experienced a tourism boom that created "long-term degradation" of its corals, according to a recent study by the American Museum of Natural History. Fast forward to the current day, and St. Martin's economy is so heavily reliant on tourism that the service industry makes up 84 percent of its gross domestic product, and 85 percent of the labor force is employed by the tourism industry, according to the Central Intelligence Agency's World Factbook. That reliance on tourism by St. Martin and other Caribbean islands, is hastening the demise of the ecosystem.

$1 trillion wiped out?

Small mound coral near St. Martin in the Caribbean. Source: David Montalvo