Someone thought building a giant taser and electrocuting everything on the seabed was a good idea.

https://www.pulsefishing.eu/what-is-pulse-fishing/techniques

If it doesn't destroy the plants too, it probably ~is better for the ecosystem than what it's replacing, but if aliens come and start dragging electrocution nets over human cities to electrocute us all, we won't be able to say we didn't have it coming.