Practical advice for selecting or determining trophic magnification factors for application under the European Union Water Framework Directive

Abstract

European Union Directive 2013/39/EU, which amended and updated the Water Framework Directive (WFD; 2000/60/EC) and its daughter directive (2008/105/EC), sets Environmental Quality Standards for biota (EQS biota ) for a number of bioaccumulative chemicals. These chemicals pose a threat to both aquatic wildlife and human health via the consumption of contaminated prey or the intake of contaminated food originating from the aquatic environment. EU member states will need to establish programs to monitor the concentration of 11 priority substances in biota and assess compliance against these new standards for the classification of surface water bodies. An EU-wide guidance effectively addresses the implementation of EQS biota . Flexibility is allowed in the choice of target species used for monitoring to account for both diversity of habitats and aquatic community composition across Europe. According to that guidance, the consistency and comparability of monitoring data across member states should be enhanced by adjusting the data on biota contaminant concentrations to a standard trophic level by use of the appropriate trophic magnification factor (TMF), a metric of contaminant biomagnification through the food web. In this context, the selection of a TMF value for a given substance is a critical issue, because this field-derived measure of trophic magnification can show variability related to the characteristics of ecosystems, the biology and ecology of organisms, the experimental design, and the statistical methods used for TMF calculation. This paper provides general practical advice and guidance for the selection or determination of TMFs for reliable application within the context of the WFD (i.e., adjustment of monitoring data and EQS derivation). Based on a series of quality attributes for TMFs, a decision tree is presented to help end users select a reasonable and relevant TMF. Integr Environ Assess Manag 2019;15:266-277. C

Monitoring priority substances in biota under the Water Framework Directive: How effective is a tiered approach based on caged invertebrates? A proof of concept study targeting PFOS in French rivers.

“…Ci designates the predicted whole-body concentration in fish (Cifish) or the measured concentration in gammarids (Cigam). Note that this equation is consistent with the generic trophic magnification model, which for hydrophobic substances is based on concentrations in lipids (Burkhard et al 2013;Kidd et al 2019).…”

“…TMFs are obtained by regression between the chemical concentrations in organisms of a food-web and their respective TLs (Borgå et al 2012); in principle, all concentrations refer to whole-body. The TMFs used for the tests were borrowed from previous studies on French riverine sites (Simonnet-Laprade et al 2019a; Simonnet-Laprade et al 2019b); while they came from field studies in a context relevant to the purpose of the present study, they were comparable to the TMFs retrieved from a literature review and screened according to Kidd et al (2019). The TMFs determined in French rivers are compiled in Table S4, and TMFs from the literature survey are compiled in Figure S1 and Table S5 in SM.…”

“…Conversely, it seems almost impossible to precisely characterize the ecosystems at all sites of a nationwide monitoring network. From a nationwide assessment perspective, a unique TMF value applicable at all sites seems preferable in practice, but challenging to confidently select (Kidd et al 2019). We carefully reviewed existing TMFs for PFOS in aquatic ecosystems (Table S4 in SM), and selected a set of TMFs derived from French rivers.…”

Comment on “Bioaccumulation of Methyl Siloxanes in Common Carp (Cyprinus carpio) and in an Estuarine Food Web in Northeastern China”

“…Thus it is strongly recommended to use all the data for TMF calculation because the real food-web is intrinsically incorporated in the assessment. Kidd et al (2018) also suggested key principles for evaluation of TMF studies including a minimum food web TL difference of 2.0 and balance in the number of samples for low and high trophic level species. Using all the data in Table 2 of Xue et al (2019), TMF were calculated as shown in Table 2 below [with TMFs of Xue et al (2019) in the last column].…”

Testing the Use of Standardized Laboratory Tests to Infer Hg Bioaccumulation in Indigenous Benthic Organisms of Lake Maggiore (NW Italy)

“…Indeed, from a risk-assessment point of view, mercury requires an approach based on establishing its bioaccumulative potential in resident biota rather than the typical toxicity-based approach commonly used for other trace elements [9,10]. Data from low trophic levels (i.e., plankton and benthic invertebrates) are necessary to estimate the trophic magnification factors (TMF) for a given food web to fulfil e.g., European regulatory requirements for bioaccumulative chemicals [11]. In the case of small organisms such as freshwater benthic invertebrates, collecting an adequate amount of biomass of resident biota for measuring Hg accumulation can be quite a time-and resource-intensive exercise.…”