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• Total Hg biomagnified through successive trophic levels in two European rivers. • Total Hg in goby and a native benthic species not significantly different. • Round goby diet indicates a preference for invertebrates over molluscs. • Goby introduction has not introduced a new pathway for trophic contaminant transfer. • Evidence for case-specificity regarding potential impacts on recipient systems. In this study, we examine multiple trophic levels in two Central European rivers (the Dyje and Elbe) to assess whether round goby invasion has changed the pattern of total mercury (Hg) transfer through trophic levels. In the absence of comparable historical data, we also examined levels for European gudgeon, a native benthic species occupying a similar trophic niche to round goby. Our data clearly indicated bioaccumulation of total Hg with increasing trophic position in both rivers. Patterns were very similar in both rivers, with no significant difference in total Hg accumulation between round goby and gudgeon. Biomagnification factors were high for gobies (highest in the Elbe) and relatively low for perch (higher in the Dyje), with levels for burbot (Dyje only) similar to those for gobies. Goby dietary analysis revealed a clear preference for benthic macroinvertebrates in both rivers, with zebra mussels taken only occasionally. Both perch and burbot had an omnivorous diet, effectively "diluting" total Hg accumulation from benthivorous fish. Our results indicate that goby invasion has not altered the pattern of trophic contaminant transfer and, consequently, has not increased threat levels to top predators and humans. Our results corroborate findings from around Europe suggesting a preference for macroinvertebrates over zebra mussels and provide further evidence for case-specificity regarding potential round goby impacts on recipient systems. [ABSTRACT FROM AUTHOR]

Methamphetamine, mainly consumed as an illicit drug, is a potent addictive psychostimulant that has been detected in surface water at concentrations ranging from nanograms to micrograms per litre, especially in Middle and East Europe. The aim of this study was to expose brown trout (Salmo trutta fario) to environmental (1 μg L−1) and higher (50 μg L−1) concentrations of methamphetamine for 35 days with a four-day depuration phase to assess the possible negative effects on fish health. Degenerative liver and heart alterations, similar to those described in mammals, were observed at both concentrations, although at different intensities. Apoptotic changes in hepatocytes, revealed by activated caspase-3, were found in exposed fish. The parent compound and a metabolite (amphetamine) were detected in fish tissues in both concentration groups, in the order of kidney > liver > brain > muscle > plasma. Bioconcentration factors ranged from 0.13 to 80. A therapeutic plasma concentration was reached for both compounds in the high-concentration treatment. This study indicates that chronic environmental concentrations of methamphetamine can lead to health issues in aquatic organisms. Image 1 • Methamphetamine and its metabolite amphetamine concentrate in tissues of brown trout. • Histological findings appear even at low concentration in liver and heart. • The tissue impairments are similar to those described in mammals. • Brown trout shows partially adaptation to methamphetamine exposure. • Environmental concentration of methamphetamine can lead to alterations in aquatic fauna. [ABSTRACT FROM AUTHOR]