Freezing winter temperatures in North America have had a devastating effect on Floridas coral reefs.<br /><br />Water temperatures need to be just right for coral to survive, but last winter was lethal, with temperatures dropping six degrees lower than average.<br /><br />Some coral areas were fortunate enough to be protected by the Florida Current - a warm water mass that blocks extreme temperature variations but much of the reef fell victim to the sharp drop in temperature.<br /><br />Al Jazeeras Cath Turner has this report.
