The Working Group on Biological Effects of Contaminants (WGBEC) investigates the biological effects of contaminants in the marine environment. The group provides research and increases the understanding of contaminant interactions and effects, including the development of inte-grated biological effects monitoring strategies, which are used to support international research and monitoring. The WGBEC has contributed significantly to the implementation and harmonization of tech-niques that can be used to evaluate the biological effects of pollutants in national monitoring programmes. An overview of national effect-based monitoring programmes of Member States is provided with the aim to support European countries and Regional Seas Conventions on their implementation. A summary of the national effects-based monitoring programmes has been pro-vided by twelve European countries represented at the WGBEC meetings. The adoption of bio-logical effects monitoring can differ widely and comparisons between approaches and the choice of biological effects methods used acts as an important tool. A summary of the main findings is presented. Furthermore, OSPAR's Hazardous Substances and Eutrophication Committee (HASEC) has en-couraged contracting parties to perform targeted biological effects monitoring to enhance the assessment of contaminants in sediment and biota towards the OSPAR QSR2023. WGBEC mem-bers contributed to the integrated biological effects approach assessment by providing data from their national monitoring activities to produce maps and figures to enable interpretations. Revision of the biological effects methods, including new techniques and developments, and the quality assurance of existing methods are core activities for the WGBEC, which require continu-ous discussion and evaluation by the group. Activities include the production of new ICES TIMES documents as well as intercalibration exercises to ensure Member States are providing comparable data for national monitoring. To this end, intercalibration exercises were performed under the BEQUALM programme for two of the more commonly used biological effects meth-ods, including micronucleus formation in mussel haemocytes and PAH metabolites in fish bile. These intercalibrations were successful despite identifying some variation in reported values be-tween laboratories. Further intercalibration exercises are planned and the WGBEC strongly sup-port the need for such quality assurance. In addition to the national monitoring activities and the different methods and approaches for determining the effects of contaminants on biological systems, the WGBEC was interested in discussing some key questions related to the potential impacts of contaminants to marine life. These questions included: the direct and indirect effects of natural and synthetic particles; how climate change and acidification parameters can interact with contaminants and influence bioa-vailability and effect; whether the structure of marine communities can be used to indicate con-taminant exposure; to provide guidance on performing risk assessments for contaminants of emerging concern; and to evaluate the effects of contaminants in marine sediments and whether current sediment toxicity tests are adequate. In addition, and as a wider concept, the linkages between contaminants in the marine environment and human health were also described.S
