Increase in concentration of a pollutant at a particular trophic level, from one link in a food chain to another. Certain chemicals occur in their largest ecological concentration in predators at the top of the food web.
The tragic 1950s mass poisoning in Minimata, Japan is the most infamous example of mercury bioaccumulation.
When the mercury enters the sea as waste material, bacteria changes it to methylmercury and it enters the small organisms such as shrimps. Afterwards, many of these small creatures are eaten by a large fish, which gets in a large amount of mercury, which means that the absorption grows, and the amount of toxics accumulates. Finally, it arrives at the top consumer – the human that eats the biggest amount of mercury, which in Minamata case lead to serious diseases.
The factory located in Minimata used mercury and dumped the methylmercury-rich waste into the bay, where it accumulated in fish.
Many residents of the town depended on fish as a crucial part of their diet and got poisoned. The exact death toll is not certain, but well over a thousand people died, and many others suffered nerve damage.