15 in an environment where 6006 is available, the more 6006 it accumulates in the kidney, if 6006 has a long biological halflife. This is not a concentration through the food web since the clams are filter feeders. The radionuclide content of bird species presents a sharp contrast, both qualitatively and quantitatively, associated with feeding habit (Table 8 and Appendix Table 10). The fairy terns and noddy terns feed mostly at sea outside the lagoon and contain small amounts of fallout radionuclides, naturally occurring 40%. of 1375, The curlew, less than the amount of They contain barely detectable amounts on the other hand, feeds on the reef and on Scaevola sp. seeds, and consequently contains relatively large amounts of 13746, as much as 2,300 pCi/g dry in muscle. The turnstones also feed along the beaches and on the reef, and contain both 6006 and 1375, The source of 1376 for the turn- stones is not known, although it could be by direct ingestion of sand particles. The yellowfin tuna, which are feeding on essentially the same organisms as the terns, contain about the same levels of 6006 as the fairy terns. The 6005 levels in the noddyterns are somewhat higher but still are of the same order of magnitude. Thus the area in which an animal is feeding is a factor affecting its radionuclide content, as expected, in relation to the distance from the source of the radionuclide.