The world’s coral reefs are facing an unprecedented crisis, threatened by warming ocean temperatures and a decline in reproductive success. In the Dominican Republic, however, a novel approach is offering a glimmer of hope: assisted coral fertilization. Conservationists are now actively intervening in the natural reproductive process, aiming to bolster coral populations and preserve these vital marine ecosystems.
Michael del Rosario, environmental education coordinator at Fundemar, a marine conservation organization, describes the scene at an underwater nursery off the Dominican Republic coast. “Oxygen tank strapped to his back, I move my fins delicately as I glide along, proudly showing off the ‘coral babies’ growing on metal structures that look like large spiders,” he explains. These “coral babies” aren’t the result of natural propagation, but rather the product of a carefully orchestrated process mirroring in vitro fertilization.
The technique, gaining traction throughout the Caribbean, involves collecting coral eggs and sperm and combining them in a laboratory setting. This is becoming increasingly crucial as climate change disrupts natural coral reproduction. Rising ocean temperatures cause coral bleaching, weakening the organisms and reducing their ability to spawn successfully. “We live on an island. We depend entirely on coral reefs and seeing them all disappear is really depressing,” del Rosario said. “But seeing our coral babies growing, alive, in the sea gives us hope, which is what we were losing.”
Fundemar’s latest monitoring revealed a stark reality: 70% of the Dominican Republic’s reefs have less than 5% coral coverage. This fragmentation of healthy colonies significantly reduces the likelihood of successful natural fertilization. Biologist Andreina Valdez, operations manager at Fundemar, explains, “That’s why assisted reproduction programs are so important now, because what used to be normal in coral reefs is probably no longer possible for many species. So that’s where we come in to help a little bit.”
The process begins with meticulous monitoring of coral spawning periods – a spectacular event where corals release millions of eggs and sperm into the water, creating a shimmering, milky spectacle. Fundemar scientists collect these gametes, perform the fertilization in the lab, and nurture the resulting larvae until they are robust enough for transplantation back onto the reef.
Inside the Fundemar laboratory, Ariel Alvarez uses a microscope to examine the tiny coral fragments growing on star-shaped ceramic pieces. The lab currently produces over 2.5 million coral embryos annually. While only approximately 1% of these embryos survive to maturity in the ocean, this survival rate surpasses that of natural fertilization on the degraded reefs.
Historically, conservation efforts focused on asexual reproduction – fragmenting healthy coral and transplanting it to new locations. While faster than assisted fertilization, this method creates clones, all sharing the same genetic vulnerabilities. Assisted sexual reproduction, in contrast, generates genetically diverse individuals, increasing the resilience of the coral population against disease. “You can’t conserve something if you don’t have it. So (these programmes) are helping to expand the population that’s out there,” says Mark Eakin, corresponding secretary for the International Coral Reef Society.
This approach isn’t unique to the Dominican Republic. Australia pioneered assisted coral fertilization, and the technique is now being adopted in Mexico, Curacao, Puerto Rico, Cuba, and Jamaica. However, experts emphasize that restoration efforts are only a partial solution.
The fundamental driver of coral decline remains climate change. Burning fossil fuels releases greenhouse gases, trapping heat and causing ocean temperatures to rise. Oceans are warming at twice the rate they were 20 years ago, according to UNESCO’s State of the Ocean Report. This warming leads to coral bleaching, a process where corals expel the algae that provide them with both color and nourishment, leaving them weakened and susceptible to disease.
The loss of coral reefs has far-reaching consequences. They provide crucial coastal protection, absorbing wave energy and mitigating erosion. For countries like the Dominican Republic, heavily reliant on tourism, healthy reefs are essential for maintaining beaches and attracting visitors. “What do we sell in the Dominican Republic? Beaches,” del Rosario points out. “If we don’t have corals, we lose coastal protection, we lose the sand on our beaches, and we lose tourism.”
Beyond tourism, coral reefs support a vast array of marine life, providing habitat and sustenance for countless species. This is particularly critical for communities dependent on fishing. Alido Luis Baez, a fisherman in Bayahibe, recounts how fishing has changed over the decades. “We didn’t have to go so far before,” he says. “But because of overfishing, habitat loss, and climate change, now you have to go a little further every day.” His father, also a fisherman, remembers a time when reefs were thriving and fish were abundant close to shore.
Despite the challenges, there is a sense of cautious optimism. Del Rosario believes there is still time to reverse the decline. “More needs to be done, of course… but we are investing a lot of effort and time to preserve what we love so much,” he said. “And we trust and believe that many people around the world are doing the same.”
