Mercury pollution can be a serious health threat as once mercury enters our body, it acts as a neurotoxin, interfering with the brain and nervous system. Mercury is emitted to the air by power plants and other industrial facilities and becomes a serious threat when it settles into oceans. As the mercury enters waterways, naturally occurring bacteria absorb it and the pollutant makes it way up the food chain as larger fish consume smaller fish. As an example, mackerel, swordfish, tuna, and grouper rank high when it comes to mercury content. We have known about the effects of mercury in fish for some time now, however, looming changes in climate could make fish accumulate even more mercury, according to a study in the journal PLOS ONE.