Everyone’s favorite marine mammal likes to keep cool, but scorching seawater appears to be wreaking havoc with dolphins in some parts of the world, a new study suggests.
Scientists first noticed the problem after a 2011 heat wave in Australia: Unusually warm seawater off Australia’s western coast that year was followed by a significant decrease in dolphin births over the next six years. By tracking hundreds of dolphins during that time, scientists also found the warmth had dropped the mammal’s survival rate by 12 percent.
“The extent of the negative influence of the heat wave surprised us,” said study lead author Sonja Wild in a statement. “It is particularly unusual that the reproductive success of females appears to have not returned to normal levels, even after six years,” said Wild, a Ph.D. student at the University of Leeds in the U.K.