Toxicity and trophic transfer of Cu from sediments along the aquatic food chain with oligochaetes (Lumbriculus variegatus) and zebrafish (Danio rerio)

ABSTRACT: Dietary route is predominant for metal accumulation in some aquatic organisms, yet the transfer of Cu from sediments to apex species and its effects on the organisms along the aquatic food chain remain poorly explored. In this study, the oligochaetes (Lumbriculus variegatus) were exposed to Cu-amended sediments at environmentally relevant concentrations for 96 h, which were supplied to adult zebrafish (Danio rerio) for 30 d. Subcellular distribution of Cu in the L. variegatus, and tissue distribution in the D. rerio, and effects on the two species were evaluated. The results showed Cu was rapidly accumulated in a dose-dependent manner in the L. variegatus with a predominant heat-stable protein (HSP) subcellular fraction (> 40%). Cu was distributed in all tissues in the D. rerio in a concentration dependent pattern. Cu altered the transcripts of genes related to Cu transporter (ctr1 and atp7a) and the levels of metallothionein2 (MT2). Meanwhile, dietary Cu delayed gonadal development, altered the fitness components, affected the hormone levels and key genes modulating fish reproduction. These results have demonstrated that Cu at its environmental concentrations from abiotic environments can readily be transferred along the aquatic food chain and causes various adverse effects on the species at different trophic levels. This study suggests incorporation of dietary exposure in the framework of the ecological risk assessment of Cu in aquatic systems.