where does the mercury come from in fish
Mercury in fish The consumption of fish is by far the most significant source of ingestion-related mercury exposure in humans and animals.[4] Mercury and methyl mercury are present in only very small concentrations in seawater. However, they are absorbed, usually as methyl mercury, by algae at the start of the food chain. This algae is then eaten by fish and other organisms higher in the food chain. Fish efficiently absorb methyl mercury, but excrete it very slowly.[5] Methyl mercury is not soluble and therefore not excreted. Instead, it accumulates, primarily in the viscera, although also in the muscle tissue.[6] This results in the bioaccumulation of mercury, in a buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish, and so on. The older that such fish become, the more mercury they may have absorbed. Anything that eats these fish within the food chain also consumes the higher level of mercury that the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. Species on the food chain can amass body concentrations of mercury up to ten times higher than the species they consume. This process is called biomagnification. For example, herring contains mercury levels at about 0.1 parts per million, while shark contains mercury levels greater than 1 part per million.[7]
Ichthys The first appearances of the ichthys symbol in Christian art and literature date to the 2nd century AD. The symbol's use among Christians had become popular by the late 2nd century, and its use spread widely in the 3rd and 4th centuries.[3] The symbolism of the fish itself may have its origins in pre-Christian religious imagery. For example, Orpheus was described as a "fisher of men" as early as the 3rd or fourth century BC.[4] The fish was used as a symbol in a number of other near-eastern religions as well, often as a sacred (or taboo) food. The fish was sacred to the goddess Atargatis, for example, who was said to cause tumors in those who ate them. Fish were only allowed to be eaten by priests during rituals devoted to Atargatis, in the belief that they represented her body.[5] Despite the thematic similarities of these various sacred fish, some scholars have argued that there is no direct link between them and the Christian symbol or practice of the Eucharist; instead, the Christian usage was probably simply part of a larger, popular religious motif of the time.[5] In the early Church, the Ichthys symbol held "the most sacred significance", and Christians used it to recognize churches and other believers through this symbol because they were persecuted by the Roman Empire.[6] The Ichthys symbol is also a reference to "the Holy Eucharist, with which the miracle of the multiplication of the loaves and fishes had such intimate connection both in point of time and significance."[7] While many Christians hang a cross necklace or rosary inside their vehicles, "the fish sticker on the car is a more conscious symbol of a witnessing Christianâ€”significantly, unlike the former, it is on the outside of the car for everyone to see".[8]