A senior geologist at the US Geological Survey has put forward a theory that coral reefs off the Florida coast and in the Caribbean are being killed by micro-organisms that live inside giant dust clouds lifted out of the African desert and carried across the Atlantic by winds.
Gene Shinn has kept a record of a coral reef formation off Key Largo since 1960 - and what was once a vibrant coral colony is now lifeless.
He soon realized that some of the major die-offs in coral reefs in the 1980s coincided with droughts in Africa that produced enormous dust clouds.
A later comparison of a fungus contained in African dust with spores that were killing coral sea fans in the Caribbean proved to be a match.