August 11, 2020 — When an intense heat wave strikes a patch of ocean, overheated marine animals may have to swim thousands of kilometers to find cooler waters, researchers report August 5 in Nature.
Such displacement, whether among fish, whales or turtles, can hinder both conservation efforts and fishery operations. “To properly manage those species, we need to understand where they are,” says Michael Jacox, a physical oceanographer with the National Oceanographic and Atmospheric Administration based in Monterey, Calif.
Marine heat waves — defined as at least five consecutive days of unusually hot water for a given patch of ocean — have become increasingly common over the past century (SN: 4/10/18). Climate change has amped up the intensity of some of the most famous marine heat waves of recent years, such as the Pacific Ocean Blob from 2015 to 2016 and scorching waters in the Tasman Sea in 2017 (SN: 12/14/17; SN: 12/11/18).
“We know that these marine heat waves are having lots of effects on the ecosystem,” Jacox says. For example, researchers have documented how the sweltering waters can bleach corals and wreak havoc on kelp forests. But the impacts on mobile species such as fish are only beginning to be studied (SN: 1/15/20).