How Freezing Coral Sperm Could Save Our Reefs

Scientist Mary Hagedorn is racing to save marine life through cryobiology

For the first time, scientists at the Smithsonian Conservation Biology Institute (SCBI) have successfully cryopreserved (or frozen) and thawed coral larvae from the mushroom coral (Fungia scutaria). Photo: The Smithsonian

For six weeks over this past summer, Mary Hagedorn waited on the island of Curaçao for the one night a year that elkhorn coral — a large branching coral that resembles elk antlers — spawn. Finally, as summer spilled into September, the environmentally threatened coral released vast clouds of egg and sperm bundles. Hagedorn had what she was waiting for: fresh coral eggs to crossbreed with 10-year-old cryopreserved, or frozen, sperm.

Hagedorn is an adjunct professor at the Hawaii Institute of Marine Biology and a research scientist with the Smithsonian Conservation Biology Institute. She has made a name for herself for creating the field of coral cryobiology, the practice of studying how coral cells respond at cold temperatures, and exploring whether freezing coral with liquid nitrogen could help preserve and expand endangered or threatened coral populations. Hagedorn is also helping to create the first genome repository for coral sperm. Her goal in Curaçao was to crossbreed 10-year-old sperm with fresh eggs collected from the western Caribbean to determine whether frozen coral sperm from one area of the Caribbean could be thawed and crossed with coral eggs of the same species in another area.

Cryobiology was once the stuff of futuristic movies. Today, it may be what saves coral reefs of the future. In October, the United Nation’s Intergovernmental Panel on Climate Change released a special report predicting a 70 to 90 percent loss of coral reefs around the world due to climate change. This is significant, because coral reefs are home to more than a quarter of all marine life at some point in their life cycle, including many of the fish species we eat.

Medium spoke with Hagedorn and postdoctoral fellow Jonathan Daly, who assists her research.

Medium: Let’s start with the basics. Why is coral cryobiology important?

Mary Hagedorn: Coral cryobiology can freeze and store the [living cells] of threatened reef areas. Then, this material can be thawed and used to reinvigorate damaged populations or reseed the oceans of the future.