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Marine heatwaves are on the rise. A surprising result from the analysis of data for fish populations in Europe and North America could change ways of thinking about the ecological consequences of such events.
The British biologist Thomas Huxley observed that the great tragedy of science is the slaying of a beautiful hypothesis by an ugly fact1. Such inconvenient truths are, however, crucial for the advancement of knowledge, and they force a reassessment of what has been taken for granted. Writing in Nature, Fredston et al.2 report a result that will cause a rethink about how marine heatwaves, periods of unusually warm temperatures in the ocean3, affect fish communities. Contrary to the authors’ expectations and to existing research, Fredston and colleagues were unable to detect an effect of these events at the ecosystem level. This unexpected negative result changes our understanding of how these heatwaves affect marine ecosystems and raises many questions.