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With an estimated 1.7 million new cancer diagnoses every year in the US, and outbreaks of malaria, Ebola and Zika rocking populations around the world, scientists are on a constant search for new compounds that might kill the cancer cells and microbes that threaten human life. Over the past two decades, they've turned increasingly to one important place: coral reefs.
Organisms that live in and around reefs play an integral, often understated, role in drug development. Though reefs cover less than one percent of the earth's surface, they are home to 25 percent of all ocean species, many of which have helped scientists crack some of the toughest medical puzzles: sea sponges were used to develop the breakthrough HIV drug AZT; mollusks called sea hares in the Indian Ocean have lent their compounds to treatments for breast and prostate cancers; toxins from cone snails have become prototypes for painkillers. Scientists in Sydney are doing promising research on coral algae to treat malaria. Last December, the FDA approved Yondelis, a cancer-fighting drug made from a compound originally isolated from a sea squirt, a small tubular marine animal that is part of the reef community. And while coral's disease-fighting resume is a bit shorter than the organisms that call it home, its role in medicine is not negligible. Made of calcium carbonate and porous in nature, it has an unusual similarity to the human skeleton and has served as a blueprint for bone graft implants.
All this promise is tempered by the very real fact that we're currently in the midst of one of the longest coral bleaching events in history—one that is destroying our opportunity to find cures for the world's most challenging and economically taxing diseases. Thanks to rising water temperature and its negative effects on the algae that keeps coral alive, reefs that were once buzzing metropolises of kaleidoscopic sea life are currently the ocean's cemeteries, stretching out for miles and miles like a pale white skeleton. New findings released this week revealed that the Great Barrier Reef is getting hit the hardest, with 93 percent of its coral bleached in total.
Compounds derived from the ocean are approximately seven times more likely to make it into drug form [than compounds from land], William Gerwick, professor of oceanography and pharmaceutical sciences at the University of California, San Diego, told VICE. There are currently 13 approved drugs for various cancers, chronic pain, the common cold, and diabetes that came from or were inspired by marine life—a number that doesn't seem particularly impressive until you consider that the field of marine pharmacology is only about 20 years old. "The literature estimates that researchers go through an average of 15,000 compounds to find one that will go through the drug testing process and reach clinical use," Gerwick said. But when it comes to marine life, it's one drug for every 2,000 compounds—a much better bet.
The staggering number and range of species in the ocean is one reason for this success, but what makes marine compounds particularly effective for drug development is how they've evolved. "Part of why coral reefs have such potential is because all of that diversity makes for tough competition," David Kline, a coral reef researcher at Scripps Institution of Oceanography, told VICE. "It's hard to survive in a reef, so a lot of organisms have had to develop really nasty venoms and poisons [to stave off predators] that are especially potent in chemical form and end up being the source of a lot of drugs."
Compounds and extracts aside, the genomes of reef-based organisms also offer medical insights for humans—algae and sponges, for instance, have complex DNA that is remarkably similar to ours. "We don't see many things like cancer in these organisms, so once we find out what genes control this, maybe we can unlock similar genes in humans and potentially put a halt to life-threatening diseases," Jose Lopez, an oceanography researcher at Nova Southeastern University in Florida, told VICE. He is part of the Global Invertebrate Genome Alliance, a research community whose goal is to sequence the genomes of thousands of organisms including reef creatures like sponges, mollusks, and jellyfish. "We may not come up with a product or chemical when we study them, but we can learn how cell structure works, or how to escape disease from their genetic code." Lopez thinks it is also possible to apply novel marine behaviors, like regeneration, to the human body. "Maybe we could regenerate our limbs if we had the right sequence from animals who do it, like starfish," he said.
That is, of course, if coral bleaching doesn't wipe out the creatures he hopes to investigate. "If the coral dies, the reef dies, and it would be extremely difficult, if not impossible, to reconstruct a whole reef. Not knowing about the sequences of the organisms or not even knowing they exist would essentially mean [gene] editing in the dark."
Gerwick, who studies the medical application of algae and cyanobacteria in cancer, inflammation, and tropical diseases, worries about future outbreaks. "Diseases mutate over time, and new ones like Zika and Ebola are emerging every year," he said. "It's not like we're done once we address just what's happening now; this is an ongoing and increasing effort, and marine organisms can help us address the changing landscape of disease, provided we don't lose them."
Lopez says the proof of bleaching's severity is strikingly obvious. "What's unsettling is the fact that we're losing organisms that have been around for billions of years and have evolved to survive—that has to be a red flag that something bad is happening."
Crumbling reef ecosystems will impact the study of known species, but there's potentially even more loss in the unknown: The field of marine medicine is still so untapped that it could take many years to continue to explore it. "I worry we'll lose potential treatments before we even have a chance to study them," Kline said. "Keeping coral healthy means we have the possibility of finding the next cure for cancer or AIDS in a sponge or mollusk. We won't know if it's gone."
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UPDATE 4/22/16: An earlier version of this story said William Gerwick worked at University of San Diego. He actually works at University of California, San Diego.