The trophic transfer of persistent pollutants (HCB, DDTs, PCBs) within polar marine food webs

- The trophic web in Antarctica was longer but more depleted than the sub-Arctic one.
- The Trophic Magnification Factor was larger in Antarctic than the sub-Arctic areas.
- Biomagnification seems to be less important than bioconcentration.
- PCB residue was mostly made up by congeners with a lower biomagnification potential.
- HCB levels were similar in polar organisms and no biomagnification occurred.

Biomagnification (increase in contaminant concentrations at successively higher levels of trophic web), is a process that can transversally impair biodiversity and human health. Most research shows that biomagnification should be higher at poles with northern sites having a major tendency to biomagnify Persistent Organic Pollutants (POPs) through their marine food webs. We investigated the biomagnification degree into two marine trophic webs combining carbon and nitrogen stable isotopes and POP analyses. We showed that the Antarctic trophic web was more depleted than the sub-Arctic one and the differences highlighted for the basal part could explain the difference in length between them. Concentrations of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and p,p'-DDE were of the same order of magnitude in the two polar trophic webs, with some values surprisingly higher in the Antarctic than sub-arctic organisms: PCBs ranged (average ± standard deviation) 1.10 ± 0.39-12.93 ± 7.62, HCB <0.10-7.28 ± 5.32, and p,p'-DDE 0.52 ± 0.18-11.36 ± 5.3 ng/g wet weight (wt) in the Antarctic organisms, and 0.53-5.08, <0.10-1.48, and 0.27 ± 0.35-5.46 ± 1.73 ng/g wet wt, respectively, in the sub-Arctic ones. The contribution of tetra- and penta-CBs to the ∑PCBs was 10-65% in the Antarctic species and 15-45% in the Arctic species. The relationships between POPs and trophic levels, and the information obtained by the Trophic Magnification Factor revealed that the Antarctic trophic web had a greater tendency to biomagnify PCBs and p,p'-DDE than its sub-Arctic counterpart. POP availability in the environment and specific ecological features may play an important role in the bioaccumulation, and biomagnification is apparently less important than bioconcentration.