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Seasonal variation in mercury and food web biomagnification in Lake Ontario, Canada

2011; Elsevier BV; Volume: 161; Linguagem: Inglês

10.1016/j.envpol.2011.10.023

1873-6424

Liang Zhang, Linda M. Campbell, Timothy B. Johnson,

Marine animal studies overview

Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern Lake Ontario. Hg concentrations, measured in 6 species of invertebrates and 8 species of fishes, tended to be highest in the spring and lowest in the summer for most biota. Yellow perch (Perca flavescens) exhibited significant ontogenetic shifts in diet and Hg, although such patterns were not evident for other species. Food web structure, as indicated by stable isotope values (δ15N, δ13C) was not static. Log-transformed Hg data were strongly and consistently correlated with δ15N values for the whole food web in each of the three seasons (slopes, 0.17–0.24) and across the entire year (slope, 0.2). While significantly different between seasons, the regression slope values are still consistent with published global Hg biomagnification rates. Our results indicate that the assessment of Hg trends in Great Lakes must take into account seasonal patterns and time of sampling.