VGE Mollusques (2015-2020)

Conversion of EQS marine water into Environmental Guide Values Molluscs – EGV molluscs

Ifremer Coordination

Type of project


 Project duration


I. Amouroux (ARC)




Water protection in Europe is regulated by the Water Framework Directive (WFD) applicable to each member of the European Union. To assess the chemical status of water bodies, Environmental Quality Standards (EQS) are defined for each priority substance (Directive 2013/39/EU). These standards are set for the majority of substances in marine water (34 of the 45 substances - or groups of substances). Considering the difficulties of sampling and analysing substances present at trace levels in the marine water matrix and the low spatial and temporal representativeness of the results obtained on spot water samples, the use of integrative matrices (molluscs, passive samplers) is preferred for monitoring the quality of the marine environment (ROCCH, Rinbio).

These results acquired on molluscs cannot be interpreted directly in relation to the EQS marine water, it is necessary to adapt the threshold to molluscs. Since 2015, Ifremer, in partnership with the OFB, has been involved in a project aimed at adapting the EQS marine water to mollusc EGVs (Environmental Guide Values) for hydrophobic and bioaccumulative organic substances and metal compounds of the WFD.

Between 2015 and 2020, two main steps were carried out:

  • An assessment based on existing data to review the conversion factors (BAF (bioaccumulation factor) and BCF (bioconcentration factor)) that can be used to convert a EQS marine water into a EGV mollusc . Based on existing data, proposals for EGVs mollusc were made after considering the applicability of the proposed thresholds. EGVs mollusc were thus proposed in 2018 and used in a regulatory framework,
  • After developing a methodology for the acquisition of mollusc BAFs in the marine environment, field BAF data acquisition was carried out at 7 sites in the Channel, North Sea, Bay of Biscay and the Mediterranean, thus enabling the conversion factors used to be refined.

 On the basis of these two steps, the mollusc thresholds for the 28 substances considered were re-examined and proposals for a joint WFD-MSFD assessment were made in 2021.

Ifremer staff


Main results :

Amouroux Isabelle, Sire Alizee (2016). Méthodologie de détermination d'un facteur de bioaccumulation (BAF) sur les mollusques en milieu marin. BAF opérationnel déterminé dans le contexte DCE . ONEMA - Office National de l'Eau et des Milieux Aquatiques , Ref. RBE/BE/ARC 16.10 ou Expertise 16-041 , 51p.

Sire Alizee, Amouroux Isabelle (2016). Détermination de Valeurs Guides Environnementales (VGE) mollusques alternatives aux Normes de Qualité Environnementale (NQE) définies dans la DCE . ONEMA , Ref. RBE/BE/ARC/16.01, 82p.

Amouroux Isabelle, Brun Melanie (2018). Substances prioritaires DCE : Cohérence et applicabilité des seuils mollusques existants en milieu marin : DCE (NQE, VGE) et OSPAR (EAC, BAC) . RBE/BE/ARC/2018.01-v2 .

Amouroux I, Gonzalez J.L., Menet F., Maheux F., Brach-Papa C., Ravel C., Chavanon F., Munaron D., Guillou J.L., Guesdon S., Seugnet J.L., Pierre-Duplessix O., Schmitt A., Lebrun L., Terre-Terrillon, A. Rozuel E., Tixier C., Bely N. (2020). Substances prioritaires DCE : Etude de détermination de facteurs de bioaccumulation (BAF) sur les mollusques en milieu marin. BAF opérationnel déterminé dans le contexte DCE. Rapport Ifremer, RBE/BE/ARC/2020, AFB, mai 2020, 65 p.