As ocean temperatures continue to rise, scientists across the world are stepping in to help corals fight back. In the Maldives, Australia, and beyond, efforts are underway to preserve and restore coral ecosystems that are facing unprecedented bleaching and collapse due to global warming.
Every year between spring and summer, coral reefs perform one of nature’s most stunning spectacles mass spawning. On certain nights after the full moon, millions of coral polyps release bundles of eggs and sperm into the ocean, creating a glowing underwater display. These bundles must fuse with others of the same species to form larvae that settle on the seabed and grow into new coral colonies.
At this critical moment, scientists from Taronga Zoo in Sydney dive into the Great Barrier Reef (GBR) to collect coral sperm and larvae for cryopreservation storing them at extremely low temperatures. This work, done at the Taronga CryoDiversity Bank, aims to preserve coral genetic material for future restoration. The facility now holds samples from 30 coral species, making it the world’s largest coral biobank.
Bleaching, caused by corals expelling their symbiotic algae when stressed by heat or pollution, not only strips reefs of colour but also weakens their ability to reproduce. Some coral species are genetically more vulnerable, and without intervention, their loss could permanently reduce the planet’s coral diversity.
“The cryopreservation and biobanking work have two objectives to secure as much genetic diversity as possible while reefs still exist, and to use those samples to breed resilient corals for aquaculture and restoration,” explains Jonathan Daly, aquatic cryobiology specialist at Taronga and the University of New South Wales.
Similar restoration efforts are underway in the Maldives, where volunteers with Soneva Conservation & Sustainability are rebuilding damaged reefs. Since launching in 2022, the initiative has created a one-hectare underwater nursery and transplanted 31,000 coral fragments around the Kunfunadhoo Islands.
These projects are part of a growing global movement to rescue coral reefs before it’s too late. Scientists are developing heat-tolerant coral strains, using biobanks to safeguard genetic material, and experimenting with artificial reefs and larval seeding to accelerate recovery.
Yet experts caution that such efforts can only buy time. Without urgent action to limit global warming to below 1.5°C, the natural resilience of coral reefs will not be enough to withstand repeated marine heatwaves.
The fight to save the world’s coral reefs, once vibrant underwater cities, has become a race against time — one that blends cutting-edge science with humanity’s last hope to preserve the ocean’s most beautiful ecosystems.