A swarm of moon jellyfish caused the Oskarshamn nuclear power station in southeastern Sweden to undergo an emergency shutdown. The jellyfish were clogging the pipes that deliver cooling water to the reactor’s turbines.

The reactor was shut down for maintenance and was scheduled to be brought back online. During the process, it had to be shut back down due to the jellyfish.

Eight years ago the same nuclear power station had a similar problem. The number 1 reactor had to be shut down for the same reason. Other nuclear power stations have had to be shutdown due to jellyfish and other small, marine life forms clogging pipes or taking over the plant.

When staff members finish clearing the jellyfish from the reactor cooling tubes, the plant will be able to open back up and restart the reactors. Before this can happen, staff members will have to figure out how to get the jellyfish out of the tubes and safely into the ocean.

Moon jellyfish can thrive in all different types of water and it can be hard to say if they will cause future problems for the power station. Jellyfish populations can grow out of control quickly and when this happens, they have been known to travel in large swarms. According to Lene Moller, from the Swedish Institute for the Marine Environment, “It’s one of the species that can bloom in extreme areas that are overfished or have bad conditions.”

Moller went on to say that moon jellyfish are common in the area and despite algae blooms and other problems within the ecosystem, the creatures are still able to live and even flourish.

Image from Wikimedia Commons.