Photos: With pristine reefs at stake, Cuba bets on coral nurseries

Luminous yellow and blue fish dart through the fragments of coral hanging from rows of pipes anchored to the seabed in Guanahacabibes, in western Cuba, while scientists in diving gear annotate their observations on waterproof clipboards. Pictured above: Divers check a coral reef being raised for research by the National Aquarium of Cuba in Havana.

This is Cuba's first coral nursery, designed to help the country repopulate its reefs, some of the most pristine in the Caribbean, and make them more resilient in the face of global threats to coral like warming waters, overfishing and illness.

The nursery was created three years ago through a landmark collaboration between the Cuban and Florida aquaria during a short-lived Cuba-US detente since rolled back by US President Donald Trump.

"We want to recover the reefs' original functions and health," Pedro Pablo Chevalier, head of the Biodiversity Department of the National Aquarium in Havana, said.

Corals are animals that settle on the ocean floor and support more sea life than any other marine environment. They also draw huge numbers of tourists, scientists and divers, and provide a natural barrier to flooding.

But since the 1970s, more than half the coral cover in the Caribbean has died, according to the Global Coral Reef Monitoring Network. Cuba's corals have been somewhat shielded by the relative underdevelopment of its coastline, lower use of fertilizer and establishment of protected areas covering a quarter of all insular waters.