Trace elements in the teeth of Steller sea lions (Eumetopias jubatus) from the North Pacific

The occurrence of trace elements in the teeth of Steller sea lions (Eumetopias jubatus) collected from the North Pacific from 1968 to 1999 is described. Using particle-induced X-ray emission analysis, we detected eight trace elements: Ca. Mn, Fe, Cu, Zn, Br, Sr and Pb. We used a general linear model to evaluate long-term trends of trace element accumulation. Zn (Zn/Ca) and Fe (Fe/Ca) levels both varied during the last three decades, and showed significant differences between animals of different age (Fe/Ca), season (Zn/Ca and Fe/Ca), and sex (Zn/Ca); both Zn/Ca and Fe/Ca ratios were higher in young males than older males. Pb was detected in 39% of the samples from Hokkaido (Japan) and 22% of those from Alaska. The high levels of Pb recorded in 1975 were thought to be related to the use of leaded gasoline during the 1970s. Our results indicate that the levels of trace elements in the teeth of Steller sea lions can be used as indicators of temporal and spatial variations of trace element pollution.