Cryopreservation Techniques for Coral Conservation

The accelerating loss of coral reef ecosystems has driven innovation in ex situ conservation, with cryopreservation emerging as a cornerstone for safeguarding genetic resources. By cooling coral cells, gametes, larvae and even small tissue fragments to ultra-low temperatures, metabolic activity is arrested and ice formation is minimised. Vitrification—transitioning water directly to a glassy state without crystallisation—has become central to modern protocols, often coupled with ultra-rapid warming via infrared lasers to prevent lethal recrystallisation. Advances now encompass isochoric vitrification, which employs constant-volume chambers to inhibit ice nucleation, enabling cryostorage of centimetre-scale fragments. Species-specific optimisation of cryoprotective agents and equilibration regimes has yielded viable recovery of Symbiodiniaceae, epithelial and gland cells, as well as fertilisable sperm and settling larvae. These integrated methods underpin living repositories, assisted evolution and global restoration initiatives aimed at reversing reef decline.

Research from Nature Portfolio

Recent studies have demonstrated the cryopreservation and revival of centimetre-scale stony coral fragments using millilitre-scale isochoric vitrification. In this passive, electronics-free system, specimens cryostored in constant-volume chambers exhibit high post-thaw viability assessed by calibrated oxygen-uptake respirometry, establishing a prototype pipeline for global deployment. Foundational work in ultra-fast laser warming has enabled survival of vitrified larvae with up to 43 per cent viability, which resume swimming and development within hours. Building on this, protocols combining vitrification solutions with laser pulses have produced the first instances of cryopreserved coral larvae settling in symbiosis with dinoflagellate partners, marking a key advance for high-throughput biobanking of complex coral–microalgal associations.

Cryopreservation Techniques for Coral Conservation publication trend

The graph below shows the total number of articles in cryopreservation techniques for coral conservation across all publications each year (not limited to Nature Index journals).

Technical terms

Cryopreservation: The process of cooling biological materials to ultra-low temperatures to halt metabolic activity and preserve cellular structures.

Vitrification: Rapid solidification of water into a non-crystalline, glass-like state, avoiding ice formation and associated damage.

Isochoric vitrification: Vitrification conducted in a constant-volume chamber to suppress ice nucleation through pressure changes.

Cryoprotective agents (CPAs): Chemicals such as dimethyl sulfoxide or ethylene glycol that penetrate cells to reduce ice formation and osmotic stress.

Cryobank: A repository for long-term storage of cryopreserved biological samples under controlled ultra-low temperature conditions.

References

1. Cryopreservation and revival of Hawaiian stony corals using isochoric vitrification. Nature Communications (2023).
2. Successful cryopreservation of coral larvae using vitrification and laser warming. Scientific Reports (2018).
3. First instance of settlement by cryopreserved coral larvae in symbiotic association with dinoflagellates. Scientific Reports (2019).
4. The World Coral Conservatory: A Noah's ark for corals to support survival of reef ecosystems. PLOS Biology (2020).
5. Cryopreservation and Cryobanking of Cells from 100 Coral Species. Cells (2022).
6. Producing Coral Offspring with Cryopreserved Sperm: A Tool for Coral Reef Restoration. Scientific Reports (2017).