Modelling the association between the El Niño Southern Oscillation and levels of legacy pollutants in Alaskan seabird eggs from 1999 to 2010

Abstract

Background

The circumpolar north has long been a sink for legacy persistent organic pollutants (POPs). Under a warmer climate, these contaminants are predicted to remobilize within environmental media where they are subject to climate processes, underscoring the need to examine the effects of large-scale climate oscillations on the fate of legacy POPs.

Methods

We apply piecewise log-linear spline regression models with non-parametric bootstrapping to measure the association between the El Niño Southern Oscillation (ENSO), a measure of Pacific sea surface temperature variability, and levels of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) measured in common murre (Uria aalge) and thick-billed murre (Uria lomvia) eggs collected from the Gulf of Alaska and Bering Sea between 1999 and 2010.

Results

In thick-billed murres, average PCB concentrations increased 143 % per unit increase in ONI during the warm phase of the ENSO, with a meta-regression pooled estimate of 0.887 (95 % CI: 0.674, 1.099). Similarly, average PBDE concentrations increased 562 % per unit increase in ONI during the warm phase, with a pooled estimate of 1.890 (95 % CI: 0.647, 3.133). During the cool phase, average PCB concentrations decreased 59 % per unit increase in ONI, with a pooled estimate of −0.892 (95 % CI: −1.400, −0.384). In common murres, average PCB concentrations decreased 51.4 % per unit increase in ONI during the warm phase, with a meta-regression pooled estimate of −0.722 (95 % CI: −0.894, −0.549), and increased 39.5 % per unit increase in ONI during the cool phase, with a pooled estimate of 0.333 (95 % CI: 0.185, 0.481). Average PBDE concentrations decreased 79.2 % per unit increase in ONI during the warm phase, with a pooled estimate of −1.572 (95 % CI: −2.357, −0.787).

Conclusion

Our results indicate associations between the ENSO and PCB and PBDE loads in Alaskan murre eggs, suggesting the ENSO may be an important factor in the fate of legacy POPs within Alaskan marine food webs. To our knowledge, this is the first paper to link the ENSO and levels of legacy POPs in Alaska's environment and may be relevant to health and food security in this region.