Despite PCBs being banned since the 1980’s, some European peri-alpine
lakes, and consequently their fish populations, are still contaminated
by these xenobiotics. We investigated the relative contribution of
physiological and trophic factors that could be implicated in fish PCB
bioaccumulation in Lake Bourget (France), one of the most contaminated
in Europe, by collecting Arctic char (n = 55) and European whitefish (n
= 89) from 2013 to 2016. Concentrations of 7 indicator PCBs were 9-168
ng.g w.w(-1) in whitefish and 90-701 ng.g w.w(-1) in Arctic char. The
fish trophic positions calculated from delta N-15 values were positively
correlated with PCB concentrations (r(2) = 0.45; p < 0.001). A
biomagnification model relying on TP and lipid content of fish was then
designed, and it confirmed this result. A Bayesian mixing model based on
delta C-13 and delta N-15 values was used to estimate the relative
contribution of preys in the fish diet, which explained a significant
proportion of the biomagnification model residuals (i.e., 17%).
Zooplankton consumption was negatively correlated with PCB
concentrations, whereas consumption of chironomids enhanced the PCB
burden in fish. Correction of the biomagnification model for individual
diets of fish increased the correlation between the predicted and
measured fish PCB contents (R-2 = 0.71; p < 0.001), highlighting the
importance of fish feeding habits in the bioaccumulation process. (C)
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