Cryopreserving living coral from the Great Barrier Reef

Preserving genetic information for the future

As reefs experience increasing loss of coral cover due to a variety of environmental events and stressors, genetic diversity in those affected populations continues to be lost. For coral species to have any chance of adapting to environmental stressors like climate change, genetic diversity is the linchpin. Strategic cryopreservation and biobanking of living coral cells to secure genetic diversity represent one approach that can mitigate some of the genetic loss that is occurring on the Great Barrier Reef. Cryopreservation can also facilitate the selective breeding of individuals of known genotypes and support scientific discovery in coral reproductive biology.

Since the inception of our program in 2011, the team has cryopreserved gametes from 26 coral species across the northern, central and southern regions of the Great Barrier Reef. These samples are held in Taronga’s CryoDiversity Bank, the largest biorepository for living coral cells in the world.  We have also demonstrated the ability of cryopreserved coral sperm to fertilise fresh coral eggs with little loss of fertilising potential. Our sperm freezing and in vitro fertilisation technologies can also be up-scaled to restoration relevant quantities.

Collection during the 2020 Great Barrier Reef spawning event

The Taronga team will work alongside AIMS scientists in the National Sea Simulator during the 2020 December spawning event. Collecting gametes from corals already in use in the SeaSim, we will expand on work from previous years, cryopreserving gametes from high priority coral species and colonies. We will also continue to refine methods for assessing sperm fertility potential. These carefully cryopreserved samples will be transported for secure storage at Taronga’s CryoDiversity Banks in NSW to expand genetic diversity and regional representation of the existing biorepository.

An invaluable living vault for the Great Barrier Reef

It is anticipated that cryopreservation and biobanking will play an increasingly important role in coral breeding and recovery activities. This work will also support crucial AIMS research programs such as assisted evolution and assisted gene flow through the targeted collection and cryopreservation of high conservation value genotypes, potentially including those that are tolerant to bleaching events.

Our research continues to improve our ability to accurately assess sperm quality and maximise the recovery of sperm after cryopreservation, which will be essential to ensure the utility of samples held in the CryoDiversity Bank. As with plant seedbanks, our CryoDiversity Bank represents an invaluable living vault, the cells of which can be thawed out decades, or even centuries, from now to produce living coral offspring. Providing that a healthy habitat exists, these offspring can bolster the genetic diversity of priority coral populations and help ensure their long-term survival.

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