Between 1773 and 1775, George Gauld, a surveyor with the British Admiralty, immortalized the coast of the Florida Keys in ink. Though his most pressing goal was to record the depth of the sea — to prevent future shipwrecks — Gauld embraced his naturalist side, too. He sprinkled his maps with miscellany that later charts would omit: where sea turtles made their nests, or the colors and consistency of sand.
Gauld also took note of the corals he saw. And in doing so he created the oldest known records of Florida reefs.
“With the early charts you can actually see the reef itself being drawn,” said Loren McClenachan, a marine ecologist at Colby College in Maine. “It matches almost exactly with the satellite data.” In a study published Wednesday in the journal Science Advances, McClenachan and her colleagues compared those 240-year-old observations with present-day satellite images.
A stark picture of shrinking coral emerged: Half of the reefs recorded in the 1770s are missing …