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Trophic Magnification Factors: Impact of Ecology, Ecosystem and Study Design



Katrine Borga, Karen Kidd, Olof Berglund, Jason Conder, Frank Gobas, John Kucklick, Olaf Malm, Dave Powell, Derek Muir


Recent reviews by researchers from academia, industry and government have revealed that the criteria used by the Stockholm Convention on persistent organic pollutants (POPs) under the United Nations Environmental Programme are unable to identify the actual bioaccumulative capacity of several substances. Rather, trophic magnification factors (TMFs) were suggested as the most reliable tool for bioaccumulation (B) assessment of POPs. TMFs are increasingly used to quantify biomagnification, and represent the average prey to predator transfer of POPs through food webs, rather than the individual species biomagnification metrics that are highly variable from one predator-prey combination to another. TMF is calculated from the slope of logarithmically transformed concentrations of POPs versus trophic level (TL) of organisms in the food web; the latter is often calculated from stable nitrogen isotope ratios (In this paper we give the background for the development of TMFs, identify and discuss impacts of ecosystem and ecological variables on TMF values, and discuss challenges and uncertainties associated with the contaminant measurements and the use of  for TL estimations. Recommendations are provided towards experimental design, data treatment and statistical analyses, including advice for users on reporting and interpreting TMF data. Interspecies and intrinsic ecological and organismal properties, such as thermoregulation, reproductive status, migration, and age - particularly among species at higher trophic levels with high contaminant concentrations - can influence the calculation of TMF (i.e. regression slope). Ecosystem status and the choice of lower trophic level organisms are important considerations in characterizing the baseline and starting point of accumulation (i.e. regression intercept). Following recommendations herein for study design, empirical TMFs are likely to be useful for understanding the food web biomagnification potential for chemicals,
Integrated Environmental Assessment and Management


TMF, POPs, trophic level, contaminants, stable isotopes, food web, field studies, regression


Borga, K. , Kidd, K. , Berglund, O. , Conder, J. , Gobas, F. , Kucklick, J. , Malm, O. , Powell, D. and Muir, D. (2011), Trophic Magnification Factors: Impact of Ecology, Ecosystem and Study Design, Integrated Environmental Assessment and Management, [online],, (Accessed April 20, 2024)
Created June 11, 2011, Updated March 4, 2022