Drivers of variability in mercury and methylmercury bioaccumulation and biomagnification in temperate freshwater lakes

The four largest freshwater lakes in southwestern France are of both ecological and economic importance. However, some them subjected to mercury (Hg) contamination, resulting the ban human consumption piscivorous fish. Moreover, beyond predatory fish, little information exist regarding Hg levels other species these ecosystems. In this context, we used a food web analytical approach investigate bioaccumulation biomagnification relation trophic structure lakes. More specifically, various organisms (macrophytes, epiphyton, invertebrates fish) were collected at analysed for carbon nitrogen stable isotopes as well total (THg) methylmercury (MeHg). A spatial variability was observed, particularly carnivorous with higher being found two more northern (median±SE: 3491 ± 474 1113 209 ng THg.g−1 dw HC L, respectively) than southern pair (600 117 911 CS PB, respectively). Methylmercury observed through webs all lakes, different magnification slopes (HC = 0.16; L 0.33; 0.27; PB 0.27), even though length chains similar between Our results suggest that rather structure, anthropogenic inputs (sulfate phosphorus ones) may have strong impact, or less directly, on methylation environments, lead concentrations exceeding environmental recommendations despite low backgrounds sediment water.