The effects of climate change can be clearly seen in almost every corner of the world, but the oceans have been hit hardest of all. Greenhouse gases dissolve in the water, making it more acidic. This has an enormous effect on marine life with hard shells, such as crustaceans and sea turtles, and it also bleaches and erodes coral — an integral part of tropical ecosystems. Damage from tourism and industrial practices have also compounded the problem and impeded preservation efforts.
Scientists from the international group SECORE (SExual COral REproduction) have now taken a significant step for the future of coral conservation by successfully demonstrating that lab-grown coral can reproduce in the wild. As detailed in Bulletin of Marine Science, this will allow researchers to give the coral a safe space to grow until it reaches sexual maturity and be placed in the wild population.
"In 2011, offspring of the critically endangered elkhorn coral (Acropora palmata) were reared from gametes collected in the field and were outplanted to a reef one year later," lead author Valérie Chamberland explained in a news release. "In four years, these branching corals have grown to a size of a soccer ball and reproduced, simultaneously with their natural population, in September 2015. This event marks the first ever successful rearing of a threatened Caribbean coral species to its reproductive age."
SECORE's approach is unlike anything that has been used by coral conservationists, as it utilizes in vitro fertilization. The conventional method is to treat the coral like a plant and grow it the same way a gardener would utilize cuttings. Small pieces are taken from a mature coral and nutured until it grows into its own individual adult. Then, it is returned back to the reef where it was taken.
While using these pieces does increase the number of mature coral, the downside is that it limits the amount of genetic diversity found within the population, putting it at risk for inbreeding depression. The pieces that are taken for growth are genetically identical to the coral from where they were taken. When they are brought back years later to reproduce as adults, there isn't any new genetic information coming in, though there is a lot more of it. This is a huge problem for endangered species, as it gives them fewer options to adapt within their environment.
Because SECORE controls how the gametes can combine, the practice promotes an increase of genetic diversity. By introducing these diverse genes into the reef when they are implanted into the wild, it gives the coral population as a whole a better chance of longevity.
Scaling up the operations at SECORE could bring dramatic changes to elkhorn reefs in just a few years by not just increasing the number of coral in the reef, but making sure it has all the genetic tools available to adapt and thrive in the face of a changing climate.