Our planets coral reef’s are not only beautiful to experience for divers, but they are integral to our underwater ecosystem. They may occupy less than 0.1% of the world’s ocean surface, but they provide a home for at least 25% of all marine species.
Unfortunately, the planet’s coral reefs are diminishing. Coral reef’s are incredibly delicate, and they are currently under threat from a variety of sources including climate change, oceanic acidification, blast fishing, coral mining, overuse of reef resources, and urban/agricultural runoff and water pollution. The world’s reefs are diminishing so fast in fact that some scientists say they could be gone by the middle of this century. In the Caribbean specifically, coral populations have declined an estimated 80 percent over the past forty years.
Scientists around the world are looking to new ways to save our reefs. Their latest effort is in vitro fertilization.
After years of captive breeding, scientists from SECORE have reported that for the first time, they have successfully raised laboratory-bred colonies of coral to sexual maturity in the wild.
Specimens of Elkhorn — a highly endangered reef-building species common to the Caribbean — were reared from gametes collected in the wild, fertilized in vitro, and planted back into the ocean. For marine conservationists, this is a big deal, but certainly not the end of our efforts to save the coral reefs.
Unlike similar reproductive efforts of the past, SECORES latest experiment doesn’t rely on asexual reproduction, which means that in the process of creating new coral, they are also giving these coral their own unique genetic type, increasing genetic diversity. Previously, fragments of adult coral were collected, spawned asexually in nurseries, and then returned to their reef. SECORE’s technique involves catching male and female gametes in the wild and then fertilizing them in the laboratory to raise larger numbers of genetically unique corals. Genetic diversity will be vital to these new corals ability to weather changing environmental challenges.
The process requires some patience, as Elkhorn corals only reproduce once a year in the wild, following the full moon in August. Over the past several breeding cycles, SECORE biologists have used nets to gently collect sperm and eggs as they’re released. The gametes are then brought to a lab and mixed in vitro to produce embryos. After a short period of time in their nursery, thee embryos are then settled into a reef. It isn’t until four years later that these embryos mature enough to reproduce again.
Successes like these are important, but even SECORE is aware that lab-grown coral aren’t going to save the reef’s over night.
“Our techniques can only support natural recovery, which means that conditions have to be appropriate to allow long term survival of outplanted corals,” said SECORE director Dirk Petersen in a statement.
One of the biggest challenges then is making sure conditions can sustain these new coral. Warmer ocean temperatures have been causing massive coral bleaching. Rising acidity levels in the ocean make it harder for corals to secrete and maintain their calcium carbonate exoskeletons. And the addition of chemicals such as oxybenzone (a common compound in sunscreen ) poison them.
If we really want to save our reefs, it’s going to require a lot more than re-populating. We need to be able to give these corals a safe environment to call home.