Mercury exposure and elimination rates in captive bottlenose dolphins

Mercury concentration in fish, faeces and exhaled air were investigated in order to evaluate total mercury exposure through the gut in captive bottlenose dolphin and escretion via intestine and pulmonary routes. Results showed that faeces account for elimination of 34-38% of dietary mercury; while only 0.9-1.2% of alimentary mercury is eliminated through exhaled air. The remaining complexation of mercury with selenium, forming insoluble tiemannite granules is discussed as an important mechanism, compementary to excretion, by which odontocetes are able to cope with elevated alimentary exposure to mercury.