TP10 Migrations: Role of Biota in Contaminant Distribution
D135-136
1:20 PM - 4:40 PM, Tuesday
() Delivery of persistent organic pollutants (POPs) by sockeye salmon (Oncorhynchus nerka) to their nursery lakes.
Krümmel, E1, Macdonald, R2, Kimpe, L1, Gregory-Eaves, I1, Demers, M1, Smol, J3, Finney, B4, Blais, J1, 1 Department of Biology, University of Ottawa, Ottawa, Ontario, Canada2 Institute of Ocean Sciences, Department of Fisheries and Oceans, Sidney, British Columbia, Canada3 Paleoecological Environmental Assessment and Research Laboratory, Department of Biology, Queen's University, Kingston, Ontario, Canada4 Institute of Marine Science, University of Alaska, Fairbanks, Alaska, USA
ABSTRACT- High contaminant loadings in orca populations of British Columbia have raised concern about toxic effects in these animals. Orcas receive the pollutants mainly through their diet, which consists primarily of pacific salmon in some populations. Pacific salmon are not only a crucial food source for top predators such as orcas, bears, and humans, but also act as important vectors of nutrients to their nursery lakes. Pacific salmon migrate to the ocean where they accumulate more than 95% of their body mass, then return to their nursery lake to spawn and subsequently die, thus fertilizing the lake. It was shown that this mechanism, which originally evolved to secure the survival of the young, now also acts as a transport route of contaminants. In a recent study, we demonstrated that lakes with the highest densities of spawning salmon could receive a sixfold increase of contaminant concentrations compared to the atmospheric loading in lakes that do not receive salmon. We analyzed eight sediment cores from lakes in Alaska with varying salmon returns. The cores were dated by 210Pb and 137Cs and extracted for polychlorinated biphenyls (PCBs) and selected organochlorine pesticides. POP concentrations in muscle tissue of sockeye salmon were also measured to identify the signature of this potential source. The patterns of the most abundant PCBs in the sediments of one of the lakes showed similarities to those found in sockeye salmon that were collected in this lake. Furthermore, the PCB concentrations in the sediments strongly correlated with the density of sockeye spawners. Our present efforts are now focused on reconstructing past sockeye salmon abundances and contaminant histories, to see if this relationship exists through time. We are also looking at a wider spatial network of lakes, including some from British Columbia.
Key words: persistent organic pollutants, nursery lakes, pacific salmon, contaminant transport