This image of a coral reef was captured by NOAA photographer LCDR Eric Johnson on the Great Barrier Reef off the coast of Australia. The Great Barrier Reef is the largest reef ecosystem in the world. It is home to over 400 species of coral and 1,500 different species of fish. Many of these species are only found on this reef. It is an extremely delicate system that has been damaged over the last few decades by both natural and man-made sources. Pollution has taken a toll, as has the voracious crown of thorns starfish.