March 19, 2021 — The eastern Pacific marine heatwave, which occurred from California to Alaska in 2014–2016, was the longest lasting heatwave globally over the past decade. A new study led by NOAA Fisheries scientists and partners looked at its effects. They found that the heatwave affected various components of the Gulf of Alaska marine food web from plankton to whales to humans. There have been various impacts, some positive and some negative. Some of these impacts persisted through 2019, when this study was completed.
“As of 2019, the Gulf of Alaska ecosystem had yet to recover from the effects of this major heatwave,” said Rob Suryan, from the Alaska Fisheries Science Center who is lead author on the study. “What also is remarkable is how rapidly conditions changed and that species from all trophic levels and age classes responded. The community composition, or proportion of species that make up the ecosystem, are distinct from what we observed prior to the heatwave.”
Since 2012, the percent of global ocean experiencing strong or severe heatwaves has increased from 30 percent to nearly 70 percent in 2016. There has also been an increase in documentation of disturbance to marine ecosystems, biodiversity, and ecosystem services associated with marine heatwaves.
In the Gulf of Alaska, the marine heatwave was particularly strong in the spatial extent, duration, and magnitude of ocean warming. It was also unique in that it extended down to the seafloor and affected a broad diversity of habitats. Its effects were seen in offshore oceanic to intertidal waters in glacial fjords.
Scientists looked at 187 biological data sets from different sampling programs in the Gulf of Alaska. They also examined long-term monitoring and synthesis efforts led by the Exxon Valdez Oil Spill Trustee Council’s Gulf Watch Alaska and the Alaska Fisheries Science Center.
From these data, scientists determined how the biological community responded as a whole and which species exhibited negative, positive, or neutral responses. They also looked at whether species showed continued, multi-year response or signs of recovery for up to five years after the onset of the Pacific marine heatwave.
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