The costs of being big in a warmer world

Scientists first documented that animals have smaller body sizes in warmer environments back in the 19th century. Today, scientists know from laboratory studies that most ectotherms (i.e. previously called cold-blooded animals), such as fish, grow faster but to smaller maximum body sizes at higher temperatures. Yet, the mechanisms driving these patterns are somehow still unknown. Hypotheses have been proposed to explain these patterns. And, theoretical models have been built, some of which project that ocean warming will result in an alarming 14–24% decrease in maximum body mass of marine fishes globally by the year 2050! Yet many of these models have been criticized because they do not have a solid physiological basis. So, discovering the physiological drivers of size–temperature relationships has an especially important applied context—forecasting climate change impacts on global food supply and ecological sustainability.