Human activities such as pollution, overfishing,‌ destructive ‍forestry, and mining practices are​ posing​ a significant threat to‌ coral reefs, some of the‌ oldest⁤ and most diverse ecosystems on Earth. Climate change, another human-driven factor, is worsening the situation by‌ causing ocean⁢ warming and acidification, potentially leading​ to the extinction of⁤ most corals within a few generations.

For the past 17 years, I ⁣have been part of a ‍global science program called the Reef Recovery Initiative at the Smithsonian’s National Zoo ‍and ⁣Conservation Biology Institute. ‍The goal of this program is to save coral reefs using the science of cryopreservation.

Understanding Cryopreservation

Cryopreservation ⁢is an innovative approach⁤ that involves storing and cooling⁣ coral sperm and larvae, or germ ⁢cells, at extremely low temperatures and holding‌ them in government biorepositories. These repositories serve as ⁢a crucial safeguard against coral extinction. If managed effectively,‌ they⁢ can help mitigate threats ‌to the Earth’s reefs on a⁤ global scale. These frozen assets can be used⁤ today, 10 years, or even 100 years from⁣ now to help reseed the oceans and restore living reefs.

The Cryopreservation Process

Cryopreservation‌ is a process for freezing biological material while‍ maintaining its viability. It ⁤involves introducing sugarlike substances, known as ⁢cryoprotectants, ⁣into cells to ⁤help ⁢prevent lethal ice formation‌ during the‍ freezing phase. If done⁢ correctly, the cells remain frozen and alive in liquid nitrogen, unchanged, for many years.

Currently, coral cryopreservation techniques primarily‌ rely on freezing sperm ​and larvae. Since 2007, ‍I have trained many colleagues in⁢ coral cryopreservation and worked‌ with⁢ them to successfully ⁤preserve ‌coral sperm. Today we have sperm from over ‍50 species of‍ corals preserved in⁢ biorepositories worldwide.

Assisted‌ Gene⁤ Flow

We have ⁣used this cryopreserved sperm to produce new coral across the Caribbean ⁢via a selective breeding process called assisted gene flow. The aim was to use cryopreserved ⁢sperm and interbreed corals that‌ would not necessarily have encountered each other—a type of ‌long-distance matchmaking.

Genetic diversity ⁤is maintained by ‌combining ⁤as many ‌different⁤ parents ⁢as⁤ possible to produce new sexually produced offspring. Since corals are cemented to the seabed, when population numbers ⁣in their area decline, new⁢ individuals can⁤ be‍ introduced via cryopreservation. The‌ hope ⁤is that these⁤ new genetic combinations might have an adaptation that will help‌ coral survive ⁢changes in future​ warming oceans.

Scaling Up the Rescue

To collect coral material faster,​ we are developing a cryopreservation process⁤ for whole coral fragments,⁤ using a method called​ isochoric vitrification.⁢ This ⁢technique ​is still in development. However, if fully⁤ successful, ‌it will preserve whole coral fragments⁤ without causing ice⁤ to form in their ⁢tissues, thus producing viable fragments after they’ve thawed that thrive and⁢ can​ be placed‌ back out on the reef.

Securing the‍ Future

Recent climate models‌ estimate that if greenhouse gas emissions‍ continue unabated, 95%​ or more of ⁤the ⁣world’s corals could die by‌ the mid-2030s. This leaves precious ⁤little time to‌ conserve the ​biodiversity and genetic diversity‍ of⁣ reefs.