From the article:

A nuclear plant in northern France shut down three reactors after a swarm of jellyfish clogged pumps used to cool the units, energy group EDF said on Tuesday, August 11.

Three reactors were taken offline on Monday and output at a fourth was cut by half, EDF said in a statement, leaving just one operating at full capacity. A sixth reactor was already offline for scheduled maintenance. "This situation has no impact on the safety of the facilities, the safety of personnel, or the environment," said EDF.

France has seen nuclear power production disrupted by multiple heatwaves and droughts this year, with EDF shutting down several reactors in June and July because of extreme heat.

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Swarms of jellyfish have also forced nuclear plants to shut down elsewhere, including a three-day closure in Sweden in 2013 and a 1999 incident in Japan that caused a major drop in output. Experts say overfishing, plastic pollution and warming seas due to climate change have created conditions allowing jellyfish to thrive and reproduce.