The Effect Screening Study commissioned by the Swedish Environmental Protection Agency aimed to assess the biological impact of environmental contaminants in eight polluted hot spot areas along the Swedish coast. The study focused on established biomarkers in fish and benthic invertebrates, questioning their efficacy in contaminant monitoring programs. In the first stage, health status and biomarkers in various species were examined, revealing contamination-related effects. In the second stage, these responses were linked to contaminant concentrations, to identify informative test species and biomarkers for biological effect monitoring in the Baltic Sea. 

Our findings revealed several contaminant groups exceeding safe levels, causing adverse effects on the amphipods and fish. In amphipods, trace metals, Hg, PBDD/F, PBDEs, HCB, and OTCs were linked to embryo aberrations and oxidative stress. In fish, HCBs, PFAS, and PCBs emerged as key predictors of multiple adverse effects and linked to growth-related traits and oxidative stress; moreover, some of the effects in fish were sex-specific. We even developed a highly accurate logistic model (>90%) to assess exposure probability based on the observed biological responses. The study underscores the need for ecologically relevant biomarkers in routine environmental management and the Marine Strategy Framework Directive, emphasizing ongoing research for effective monitoring tools and improved assessment criteria.