"Lots of people have speculated that animals with short generation times will simply adapt to change," Graeme Hays, a marine scientist at Australia's Deakin University, told NBC News in an email. "We show that is not the case."

The range and abundance of the cold-water plankton, Calanus finmarchicus, declined while the warm-water species, C. helgolandicus, expanded its range and increased in abundance.