Dr. Emily Hall, manager of Mote's Ocean Acidification program, shares how the harmful chemistry change called ocean acidification (OA) is a growing challenge for marine ecosystems, including vital coral reefs. OA happens when excess carbon dioxide enters the ocean, causing the water to acidify. If you're a coral building a calcium carbonate skeleton: Watch out! OA may work like "osteoporosis of the sea" affecting your skeleton and your survival odds. Hall and colleagues want to know which marine life will be "winners" and "losers" in a more acidic ocean.