Freezing on the beach: A robust coral sperm cryopreservation design

Area of Science:

• Marine Biology
• Cryobiology
• Biotechnology

Background:

• Coral sperm cryopreservation is crucial for marine conservation.
• Existing methods require reliable, portable, and affordable hardware.
• Previous cooling rack designs showed variability in cooling rates.

Purpose of the Study:

• To develop and test a second-generation, conduction-based cooling rack for coral sperm cryopreservation.
• To create a robust, travel-ready, and inexpensive hardware solution.
• To improve the consistency of cooling rates compared to older designs.

Main Methods:

• Assembly of a cooling rack using 3D-printed and commercial components.
• Testing cooling rates for 1-mL and 0.5-mL cryovials from -10 to -80 °C.
• Comparison of cooling rate variability with a previous design.

Main Results:

• The second-generation rack demonstrated repeatable cooling rates: -22.9 ± 1.9 °C/min for 1-mL samples and -35.4 ± 3.3 °C/min for 0.5-mL samples.
• This represents a significant improvement in cooling rate consistency.
• The new design showed reduced variability compared to the older model (-31.8 ± 7.1 °C/min for 1-mL samples).

Conclusions:

• The developed cooling rack is a robust and reliable tool for coral sperm cryopreservation.
• The design's affordability and portability facilitate its use in the field.
• Open-access design files and a manual promote widespread adoption and further innovation in coral banking technology.