| Summary: | There is a continuing need to monitor contamination of the marine environment by xenobiotic compounds, particularly those which are persistent and accumulate in food chains. Eggs of marine birds have proven to be an efficient and effective means of measuring and tracking substances, such as persistent organic pollutants (POPs) and mercury which are transferred from the female bird to the egg via yolk lipids or proteins. Here we report and discuss data from long term monitoring of POPs and mercury in seabird eggs from the northeast Pacific. For this program, the marine system was divided, and representative species selected. The nearshore subsurface is monitored using two cormorant, Phalacrocorax, species, auritus and pelagicus, both feed on a variety of benthic and pelagic fish. The offshore subsurface is monitored using the rhinoceros auklet, Cerorhinca monocerata, a feeder mainly on small pelagic fishes, with the offshore surface species, the Leach’s storm-petrel, Oceanodroma leucorhoa, which feeds mainly on surface plankton and larval fishes. At three breeding colonies each along the Pacific coast of Canada and at four year intervals 15 eggs are collected and analyzed as five pools of 3 eggs each. Among the chemicals measured in this long term study are the perfluorinated carboxylates and sulfonates. Data from a recent retrospective study, using archived samples collected from 1990 to 2011, shows, as reported for more polluted environments, that PFOS (perfluorooctane sulfonate) increased in continental shelf ranging auklet eggs until the late 1990s and have declined since then. In contrast, another compound, PFUdA (perfluoroundecanoate) increased steadily in eggs of both near and offshore species. Stable isotopes will be used to examine the possible role of dietary variation, possibly related to marine regime shifts, in variation in contaminant levels in these monitored seabirds.
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