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Organized Oral Session

Hybrid Session

Session: : New Ecological Insights from Stable Isotope Ratios of Amino Acids

OOS 21-4 - How does mercury transfer along a food chain? An improved biomagnification factor applied to freshwater fish

Tuesday, August 8, 2023
10:45 AM – 11:00 AM PDT
Location: 255
Biomagnification is commonly quantified by two indices: trophic magnification factor (TMF) and biomagnification factor (BMF), which measure how much a pollutant accumulates through a food web and transfers from one organism to another, respectively. However, both indices have uncertainties due to simplified assumptions about diet sources and trophic position (TP). This study presents an improved BMF (i.e., BMF′) applied to mercury bioaccumulation in freshwater fish from four sites before and after rainfall. The diet source and TP of each fish were identified using nitrogen stable isotope of amino acids (δ15NAAs) combined with bulk carbon isotope (δ13C). The BMF′ was calculated using TP and diet contributions derived from MixSIAR. The results showed that BMF′ values (1.3–27.2 and 1.2–27.8) were generally higher than TMF values (1.5–13.9 and 1.5–14.5) for both total mercury and methyl mercury. The BMF′ implying actual mercury transfer pathway is more cautious index than relatively underestimated TMF for risk assessment. The improved BMF provides novel insight into the behavior and trophic transfer of pollutants like mercury.