With the increasing threat of climate change, scientists are actively looking for a way to save coral reefs from being destroyed. The main focus of these efforts is preventing coral bleachings, which can result in coral death and are triggered by the rising water temperatures. As of now, the promising approach to solving this issue is the genetic modification of coral and its symbiotes.
Coral bleaching in particular is caused by the corals expulsion of an algae commonly referred to as zooxanthellae. The algae forms a symbiotic relationship with the coral in which it provides the coral with food to grow and survive. When a reef is under environmental stress these algae stop producing food leading and are expelled from the coral’s tissue, which causes coral bleaching. By genetically modifying these algae to resist heat and giving them the ability to function in higher temperatures we can decrease the amount of coral bleachings. Among zooxanthellae there are a number of different species, and a small number of them have the ability to resist heat. Corals those that are dominated by Clade C have been proven to have me more tolerant of heat in comparison to those where it is less dominant. We hope to find a way to genetically modify both the algae itself and the coral so that this heat resistance trait is magnified in the coral.
A promising solution to combating the rising temperature of the ocean is gene assisted evolution. Scientists hope to genetically enhance the corals heat tolerance so that they resist the increasing water temperatures. Professor Madeleine Van Oppen, one of the leading scientists in this field is currently conducting various experiments focused on the assisted evolution of both coral and its symbiotes. One of her more recent efforts involves breeding coral in more demanding environments to see if the coral would become more resistant. Another one of her efforts involves the application of CRISPR to coral. Scientists are looking to select strains that are responsible for heat tolerance and hope that the activation or deactivation of certain genes that are involved n heat resistance will be passed on to newer generations. Dr. Philip Cleves is another leading figure in this field of research and was the first scientist to successfully use microinjection to insert CRISPR-Cas9 into coral embryos. Through this process Cleves is able to knock out certain genes to determine if they play a role in heat resilience. Cleves isn't really focused on actually genetically engineering new kinds of coral, but instead wants to decipher the DNA of coral.
Another approach is Marine Permaculture, which was developed by the Climate Foundation. Marine Permaculture can restore overturning circulation and in turn prevent thermally induced photobleaching. This solution involves the ocean farming of kelp and seaweeds, which helps return nutrient up-welling to pre-global warming levels. In doing so, Marine Permaculture can effectively cool the reef and provide key nutrients for the growth and survival of reefs. This actively lowers the reef temperature through the restoration of overturning circulation while also cultivating seaweed that can be used for carbon storage technology. This can directly reduce global greenhouse gases, which also has an impact reef environments. Rather than focusing on increasing coral resilience, the Climate Foundation is trying to restore the cooler, pre-global warming conditions of the ocean.