Selenium status in Charadriiformes. Tissue distribution and seasonal, geographical, and species variation.

The distribution of selenium in a marine wader, the Oystercatcher (Haematopus ostralegus) is given by the levels in 15 tissues and plasma. Red blood cells (RBC) contain the highest level (23 mg/kg dry wt) followed by liver, lung, and kidney (17-19 mg/kg). Most other tissues range from 3-10 mg/kg. The average kidney and liver concentrations of the Oystercatcher belong to the concentrations characteristic in birds. However, the Oystercatcher's tissue selenium concentrations are in general four- to fivefold mammalian levels, but in liver and lung, 11- to 13-fold and in the RBC, 12- to 33-fold. The selenium plasma and RBC levels of the Oystercatcher vary during the year from 280 to 410 micrograms/L and 13 to 30 mg/kg dry wt, respectively; the plasma concentrations are positively correlated with the RBC selenium concentrations. An overview of literature data shows that the selenium kidney and liver concentrations of birds do not vary with geographical latitude and size (length) of the birds. In species of the orders Charadriiformes and Procellariiformes, high selenium kidney, and to a lesser extent liver, concentrations may occur. A function of selenium in antioxidation is suggested.