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Researchers call for regional and context-specific approaches to these extreme events

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News — Woods Hole, Mass (February 28, 2025) -- Marine heatwaves can create chaos in ocean ecosystems and disrupt coastal economies. In recent years, they’ve made headlines for driving drastic changes in fish migration, more frequent occurrence of harmful algae blooms but also for fueling storm systems. Yet in some situations, the broad definition of a marine heatwave—ocean temperatures exceeding a seasonal threshold for five consecutive days— leaves more questions than answers.

In a new commentary published in , an interdisciplinary group of researchers from Woods Hole Oceanographic Institution () and San Diego State University () call on scientists to be more specific in their work. Different scientific disciplines prioritize varied aspects of marine heatwaves, including what drives them and the regional impacts they may have.

“Ecologists examine biological effects, such as the migration of marine life and food sources. Meanwhile, physical oceanographers analyze underlying drivers from a statistical perspective, and climate scientists seek to attribute causes,” explained , a WHOI physical oceanographer. “The detection, interpretation, and impact assessments of marine heatwaves are heavily influenced by methodological choices, such as defining temperature baselines and selecting data sources.” 

Belfast Bay is an inlet of the Penobscot Bay, Gulf of Maine, and Atlantic Ocean located by Belfast, Maine. Like most coastal Maine communities, Belfast has a rich commercial fishing history. (Photo credit: Rachel Mann)

"As scientists, we often aim for standardized methodologies to ensure comparability across studies. However, the drivers of anomalously warm waters and their ecological impacts can vary by region and species,” said SDSU Postdoc , a co-lead author of the study and member of the . “So while a 'one-size-fits-all' approach to identifying and characterizing marine heatwaves may seem ideal, our goal as a community should be to determine the most suitable practices for specific regional oceanographic and ecosystem dynamics."

In 2012, a long-lasting marine heatwave wreaked havoc on Maine’s marine life and fishing industry. At times, water temperatures were nearly 40°F above average. The state’s staple lobster fishery suffered. According to the study on the occurrence, lobster yields weren’t low, but early molting resulted in a massive price drop. Due to pronounced ocean warming off the Northeast U.S. coast since 2012, fishers more frequently find warm-water fish and squid, not usually found in the region.

“Places like the Gulf of Maine are extremely dynamic, so the use of different methods to detect marine heatwaves lead to strong differences in how we might characterize these events,” said , a WHOI biologist and member of the Marine Predators Group. “Conversely, when you look at an area like the Gulf of Mexico, a variety of methodologies for identifying marine heatwaves lead to less noticeable differences in the resulting detection of these events.”

Sea surface temperature anomalies (red-blue gradient) and marine heatwaves (outlined in white) in the Gulf of Maine in February 2023 are shown, as measured by two contrasting methodological pathways. (Graphic Credit: Laura McDonnell, ©Woods Hole Oceanographic Institution)

“As we see marine heatwaves happening more frequently, taking a regional approach to studying them will become more important. These extreme events can result in commercially important marine species losing suitable habitat in important areas they’d ordinarily occupy reliably” explained WHOI Postdoc , the study’s co-lead author and member of the Marine Predators Group. “Scientists need to take regional and context-specific approaches to studying marine heatwaves so that we can support marine organisms and the lives and livelihoods of those who depend on ocean ecosystems.”

*This work was supported by NASA and the Northeast Regional Ocean Council.

About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the world's most extensive suite of data-gathering platforms. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu