Ocean currents act much like a conveyer belt. they transport warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. this, currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth's surface.
This is called Biomagnification - concentration of toxins in an organism as a result of its ingesting other plants or animals in which the toxins are more widely disbursed.