Coral Conservation:The Tides are Changing

The rainforests of the sea. Coral reefs are the most diverse ecosystem on the planet and are of immense value to both the marine world and our own. They are the protectors of the coastline, a haven for young fish, a source of valuable nutrients for marine life and are of course one of the most beautiful sites in the world.

The ecosystem services that these reefs provide are priceless. However, since money usually does the talking, take a moment to reflect on the fact that The Great Barrier Reef alone generates more than 1.5 billion dollars every year for the Australian economy from fishing and tourism. Unfortunately, due to overwhelming pressure, these invaluable lifelines are facing extinction. In 2005 alone, the U.S lost half of its coral reefs in the Caribbean due to a colossal bleaching event. At present, it is estimated that 27 percent of the global reef ecosystem has been lost due to both climate change and human activities. Though most of us may not live in the immediate vicinity of a beautiful coral clad coastline, their bleaching and subsequent demise will affect us all.

Photo by me: Coral reef located off the coast of Gili Trawangan, Indonesia.

Gene Editing to the rescue? Some researchers are now considering the use of gene-editing tools such as CRISPR to help us understand the genetic basis of coral biology, so to influence conservation practices in the future. Whilst this gene-editing practice is carried out across the spectrum of biological sciences from plants to bacteria and even in humans, its application in coral is a rather novel technique. This owes – in some part- to the rather infrequent, whimsical breeding practices of coral which take place when the conditions are just right, usually no more than twice a year and always under a full moon. During this tiny window, coral release a cloudy rich soup of egg and sperm cells and when the sex cells meet they fuse and form zygotes (fertilised single cells). It is within these zygotes that scientists are able to ‘cut and paste’ the altered DNA sequence into the coral zygotes, which will multiply throughout the organism as it grows and develops. Not only does this require cutting edge CRISPR techniques but also a deep understanding of coral growth cycles and the likelihood of reproduction. The use of CRISPR to modify the DNA of coral has been demonstrated with genes that code for specific growth factors as well as red and green fluorescence, with genetic changes observed in about 50% of the population.

The hope is that this research can provide the blueprint for future genetic manipulation in coral, perhaps one day a more temperature tolerant species could be flourishing along our shores. What is for sure, the more we can understand about the underlying basic mechanisms of how coral works, the more successful the conservation efforts in the future. It is certainly a step in the right direction. The rapidity of coral decline, accelerated by climate change is certainly a 21st century problem, in need of a 21st century solution.

Extra Information

What is coral? - Marine invertebrates that typically live in colonies formed of hundreds and sometimes thousands of individual organisms (polyps). - Produce calcium carbonate to form a hard protective skeleton - Feed at night on a variety of small organism from microscopic zooplankton to small sh! - Many have a symbiotic (mutual) relationship with certain algae such as zooxanthellae. The coral provides the algae with a home and in return the algae photosynthesise, providing the coral with food as well as acting as an in house maid service, removing waste material.

What is coral bleaching?

When the coral is stressed (e.g. warmer than normal water), they vacate the photosynthesising algae from the premise. Expelling the algae, causes the coral to turn white. Contrary to popular myth, this does not kill the coral. They are able to recover if the stress is removed. However, the longer they go without recovery the higher the chance of mortality.