In Vitro Fertilization Could Help Restore Vulnerable Coral Reefs

It’s no secret that the world’s coral reefs are at risk. Pollution, dredging, overfishing and, especially, acidic, warming waters are pushing these complex ecosystems to the brink of destruction, and marine scientists and researchers have been stymied in attempts to restore their health.

Saving them isn’t just the right thing to do, it’s a necessity if we want to keep our oceans healthy and viable. Coral reefs provide nurseries for nearly a quarter of the ocean’s fisheries, help protect shorelines from storms, and offer underwater wonders for snorkelers and divers.

Now, a project at San Francisco’s California Academy of Sciences offers hope for what marine biologist Bart Shepherd calls ‘one of the most magical and beautiful places on Earth’. “It’s this incredible city of organisms that all learn to live together.  All these animals are competing to try and take over space and try to get access to sunlight, to nutrients in the water.”

Shepherd is director of the Academy’s Steinhart Aquarium, and, with the Academy’s curator of ichthyology, Luiz Rocha, directs the appropriately-named Hope for Reefs initiative.

Reefs under stress

Human activity and increasingly warm and acidic ocean water are taking a heavy toll on the world’s coral reefs. A recent aerial survey found more than two-thirds of the coral in Australia’s Great Barrier Reef is experiencing “shocking” amounts of bleaching, and Rocha says human-induced climate change is devastating other reefs as well.

“When coral gets stressed, in most cases because of warm water, it expels the algae,” he explains. Algae have a symbiotic relationship with the coral polyps. The coral provides a protective environment for the algae, which provide corals with essential nutrients and their incredible colors. “So,” Rocha adds, “when the algae gets out, the coral gets bleached and becomes white.” That bleaching can lead to the coral’s death.

Restoring the reef

Various methods have been tried to bring back reefs. The most successful so far has been artificially accelerating a natural process called fragmentation. Researchers purposefully break off coral branches, allow the pieces to recover and grow, and then plant them back onto the reef.

But Shepherd points to a long-term problem with that approach. “You are producing thousands of identical genetic clones of the same coral from one parent colony. So, you’re really reducing the genetic diversity that’s out there on the reef and the ability of the coral to respond, perhaps, to things we don’t even know are going to happen.”

So, the Hope for Reefs crew turned to a unique method pioneered by the coral conservation group Secore International.  In 2011, it began using in vitro fertilization to restore the health of dying coral reefs. Endangered elkhorn coral off the coast of its field station in Curaçao was the test case. Shepherd says, “So, we actually have proven that you can go and collect gametes – sperm and eggs, fertilize them and grow them in a laboratory for a short period of time, plant that baby coral back out on the reefs and, within five years, it will grow up and spawn with its wild counterparts on the reef.”

A small window of opportunity

Corals only spawn once a year, at night around a full moon. During those couple of nights, millions of the corals’ sex cells float to the surface, but, Shepherd explains, more than 99 percent don’t make it.

“What we’re able to do is intercede at a point where most of the sperm and eggs will be eaten by fish. We put a net over the coral and we collect those sperm and eggs, bring them back to the lab, cross-fertilize them and go from there.”

Hope for Reefs doesn’t stop with restoration. Shepherd says educating local governments and community stakeholders to save their coral reefs is key to the success of the project — and time is crucial.


“We need communities that want to help manage their reefs, that are going to look at the environmental conditions and why they are the way they are and what we can do to improve them. Reducing sewage outflow, reducing sedimentation, reducing the fishing pressures on herbivores, and there’s a holistic approach to managing reefs that really needs to be in place in order for this to work.”   

And, says project co-director Luiz Rocha, that approach includes communication. “We don’t safeguard our results. We know that it is urgent. We know that we have to talk about it as soon as possible. So, we are working on our scientific publications that take quite a while to be published, but we also take to the field with us a media person, a science writer, a photographer that will be talking about our results in real time, most of the time.”

Looking ahead

Hope for Reefs has just finished the first year of its five-year project and everyone involved is optimistic.  The challenge is to scale up in vitro fertilization to restore endangered coral reefs worldwide before they are lost. The project hopes to seed one million global corals by 2021.

With a commitment of nearly $13-million from the California Academy of Sciences, and a new partnership with The Nature Conservancy, twenty new expeditions are planned. First up, the degraded reef at Secore International’s field station in Curaçao and, then, on to the Yucatan Peninsula and the Great Maya Reef.


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