Trace metals in seabirds, Steller sea lion, and forage fish and zooplankton from central California

We studied concentrations of the trace metals, aluminum (Al), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), silver (Ag), cadmium (Cd), and mercury (Hg), in krill (Euphausia pacifica and Thysanoessa spinifera), two species of fish (short-bellied rockfish Sebastes jordani and northern anchovy Engraulis mordax), four species of marine bird (Common Murre Uria aalge, Brandtʹs Cormorant Phalacrocorax penicillatus, Rhinoceros Auklet Cerorhinca monocerata, and Pigeon Guillemot Cepphus columba) and a pinniped, (Steller sea lion Eumetopias jubatus) from the Gulf of the Farallones, central California in 1993. Geometric mean levels of some trace elements in Steller sea lions were elevated (Cu, 91.0 mg/kg dry weight; Hg, 19.0 mg/kg; Se, 4.1 mg/kg). Levels of Hg in Pigeon Guillemot (3.5 mg/kg) were also elevated. Mercury increased whereas Pb decreased with increasing trophic level in the Gulf of the Farallones food web. Selenium levels were highest for krill and sea lions, and intermediate for fish and birds occupying mid trophic levels. Results indicate little to relatively high trace metal contamination of upper trophic level marine wildlife in the central California coastal marine ecosystem.