Why would tuna have higher levels of mercury than other fish?Explain the mechanism that acts across trophic levels
Mercury becomes concentrated in tuna through the process of bioaccumulation. Bioaccumulation occurs when an organism consumes a toxin at a rate faster than its body can eliminate the toxin. Bioaccumulation results in highest concentrations in the organisms at the highest trophic levels. There are several factors that influence mercury bioaccumulation in tuna. These factors include the diet, size, age, and type of the tuna.
Tuna are predator fish that eat smaller fish, squid, and crustaceans. Tuna have a rapid metabolism which means they eat a lot and digest their prey quickly. The mercury from the tuna's food builds up in its fatty tissues faster than its body can remove it. Large tuna generally have higher mercury levels than smaller tuna. The older that a tuna is, the higher its mercury level will be. Albacore (white) tuna is higher in mercury than canned light tuna.
Tuna doesn't have the highest levels of mercury in fish. The EPA and FDA state that shark, swordfish, king mackerel, and tilefish have higher mercury levels than tuna. These are also predator fish.