Nature World: Corals in the Great Barrier Reef are diminishing, and scientists are blaming ocean acidification for their dangerously low growth rates, a new study describes. Coral growth rates have plummeted 40 percent since the mid-1970s, and given that the Australian reef is the site of the largest collection of corals - over 400 types - scientists are getting worried. "Coral reefs are getting hammered," study leader Ken Caldeira of the Carnegie Institution said in a press release. Not only from ocean acidification,...