First Cryorepository for Coral Larvae: Safeguarding Corals for Future Generations

Abstract

Research on the development of innovative cryobanking techniques can aid coral restoration and conservation. This study applied a customized freezing device and “cryojig” along with vitrification and laser warming techniques to create the first cryorepository for pelagic-phase larvae of the corals Seriatopora caliendrum, Pocillopora verrucosa, Stylophora pistillata, and Pocillopora acuta. Three vitrification solutions (VSs) were prepared, with each composed of two of four cryoprotective agents. These included VS1: 2 M ethylene glycol (EG) and 1 M propylene glycol; VS2: 2 M EG and 1 M glycerol; VS3: 2 M dimethyl sulfoxide and 1 M EG. Larvae were then mixed with the VSs, 40% (w/v) Ficoll, and 10% (v/v) gold nanoparticles (GNPs) at a final concentration of 1.2 × 10¹⁸ particles/m³ and using our customized device for vitrification and laser warming. Over a thousand coral larvae (576 S. caliendrum, 376 P. verrucosa, 238 S. pistillata, and 524 P. acuta) were successfully stored in the cryorepository and the proportions of coral larvae that were noted to be actively swimming or settled after vitrification and laser warming. This is the first project to establish a coral larvae cryorepository, and the methods applied could represent a critical tool for reef restoration and maintenance of marine biodiversity.