Comment Reminded of old SF story in Analog (Score 1) 27
Jellyfish that could concentrate heavy metals from the water they live in.
You would let them breed and clean up water in an area, then release a pheromone to get them to jump into your harvester ship, render them and get the contaminants.
They were released in an area with an old nuclear waste dump, so some of the stuff they were concentrating was potentially fissile.
Especially so when the pheromone told them to go up the water intakes at a power plant...