In Vitro for Corals? Kind of, in the Caribbean

Oxygen tank strapped to his back, Michael del Rosario moves his fins delicately as he glides along an underwater nursery just off the Dominican Republic coast, proudly showing off the "coral babies" growing on metal structures that look like large spiders. Del Rosario helped plant these tiny animals in the nursery after they were conceived in an assisted reproduction laboratory run by the marine conservation organization Fundemar. In a process something like in vitro fertilization, coral egg and sperm are joined to form a new individual, a technique gaining momentum in the Caribbean to counter the drastic loss of corals, per the AP.

• Climate change: Oceans are warming at twice the rate of 20 years ago, per UNESCO—and that's devastating for corals. Rising heat causes them to feel sick and expel the algae that live in their tissue and provide them both their striking colors and their food. The process, known as bleaching, exposes the coral's white skeleton. The corals may survive, but they're weakened and vulnerable to disease and death if temperatures don't drop. Half of the world's reefs have been lost since 1950, per research in the journal One Earth.

• Help from Fundemar: The state of corals around the Dominican Republic, as in the rest of the world, isn't encouraging. Fundemar's latest monitoring last year found that 70% of the nation's reefs have less than 5% coral coverage. Healthy colonies are so far apart that the probability of the eggs of one coral (which is an animal, not a plant) meeting another's sperm during the spawning season is decreasing. Fundemar monitors spawning periods, collects eggs and sperm, performs assisted fertilization in the laboratory, and cares for the larvae until they're strong enough to be taken to the reef.
• Changing techniques: In the past, Fundemar and other conservation organizations focused on asexual reproduction. That meant cutting a small piece of healthy coral and transplanting it to another location so that a new one would grow—a method that can produce corals faster than assisted fertilization. The problem, per Fundemar operations manager Andreina Valdez, is that it clones the same individual, meaning all those coral share the same disease vulnerabilities. In contrast, assisted sexual reproduction creates genetically different individuals, reducing the chance that a single illness could strike them all down.
• More than pretty creatures: For countries such as the Dominican Republic, in the so-called "hurricane corridor," preserving reefs is particularly important. Coral skeletons help absorb wave energy, creating a natural barrier against stronger waves. "What do we sell in the Dominican Republic? Beaches," del Rosario says. "If we don't have corals, we lose coastal protection, we lose the sand on our beaches, and we lose tourism."

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