May 13, 2021

Years After the Pacific Marine Heat Wave, Ecosystem Shifts Persist

A humpback whale, one of the species affected by the Pacific marine heat wave, breaches in Kenai Fjords National Park in the Gulf of Alaska. Credit: Kaitlin Thoreson, National Park Service.

From 2014 to 2016, the Gulf of Alaska experienced the worst marine heat wave of the decade. From single-celled organisms to top predators, practically no level of the ecosystem was left unscathed. During the Pacific marine heat wave, tens of thousands of dead seabirds washed up on beaches, unusually low numbers of humpback whales arrived in their summer habitats, and toxic algal blooms spread along the West Coast of North America.

Now, a new study in Scientific Reports casts doubt on whether Gulf ecosystems will be able to return to their pre–heat wave conditions. This study—a collaborative effort between researchers at NOAA and several other government and research organizations—combined dozens of data sets to build a detailed picture of how many heat wave–induced changes have persisted. Thanks in part to long-term monitoring efforts by Gulf Watch Alaska, a program established in 2012 to assess the ongoing effects from the 1989 Exxon Valdez oil spill, scientists were able to compare pre–heat wave and present conditions in several different sections of the ecosystem.

“We were able to show these impacts—from the intertidal out to the pelagic [open ocean] ecosystem, and from algae and phytoplankton on up to whales and commercial fisheries, and a lot of different species in between,” said Robert Suryan, a NOAA marine biologist and lead author of the study.

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