Known as the 'forests of the ocean', coral reefs represent an entire underwater ecosystem, teeming with life. But this ecosystem is under threat. Researchers from The University of Queensland and Colby College in the USA have used old 18th century nautical charts and compared them to modern satellite data as a novel way to understand coral loss over a period of 240 years. Michael Wheeler spoke with lead researcher Loren McClenachan, assistant professor at Colby College to find out more.