Four reactors at France’s Gravelines nuclear power plant were shut down late Sunday due to a swarm of jellyfish in the cooling systems, operator EDF said on Monday, likely due to rising water temperatures because of global warming.

A nuclear power plant in northern France hit by a jellyfish invasion was getting back online on Wednesday, operator EDF said, with service restored at the first of four closed reactors. The Gravelines facility near Dunkirk on the French coast is the largest nuclear power plant in western Europe,

Four of the plant’s reactors shut down after swarms of jellyfish clogged its pumping stations. It isn’t the first time the creatures have thwarted nuclear plants.