Important questions in this context are if and how uptake, bioaccumulation and trophic transfer of NPs differ compared to non-nanoparticulate counterparts. Even less is known on their fate within food webs. The current knowledge and understanding of the dietary uptake and bioaccumulation of NPs in aquatic organisms is limited. Environmental significance Man-made nanoparticles (NPs) may accumulate in sediment and be taken up by benthic invertebrates that serve as food for higher trophic level organisms, such as fish. Furthermore, there were no indications of induction of oxidative stress in fish intestine and liver, suggesting that effects from environmentally relevant Cu/CuO NP exposure via the diet may be minimal. tubifex to stickleback may be limited compared to dissolved Cu. Altogether, the results suggest that sediment-associated CuO NPs can enter the aquatic food web, but that transfer of CuO NPs from T. In CuO NP-exposed fish, Cu and mta mRNA levels were noticeably lower than in CuCl 2-exposed fish and inversely correlated with the amount of Cu in their faeces, suggesting that a large fraction of NPs was egested. aculeatus fed CuO NP- and CuCl 2-spiked food packages (2 μg Cu per g fish ww per day 7 days) showed increased Cu concentrations (∼13 and ∼31 μg Cu per g dw compared to control, respectively) and metallothionein ( mta) mRNA expression in intestinal tissue. Yet, metallothionein-like protein levels were significantly elevated in CuO NP-exposed worms compared to the control, while they were not in CuCl 2-exposed worms. tubifex, no significant differences in Cu accumulation were detected following 7 days of exposure to sediment-associated CuO NPs or CuCl 2 (100 μg Cu per g dw sediment). A key methodological achievement of study 2 was the development of worm homogenate-based food packages, which allowed controlling CuO NPs and CuCl 2 dosing of fish. tubifex) to fish ( Gasterosteus aculeatus, three-spined stickleback). Study 1 focussed on transfer from sediment to worms ( Tubifex tubifex) and study 2 on transfer from worms ( T. We tested this hypothesis in a proof-of-concept approach consisting of two studies examining the transfer of copper( II) oxide NPs (CuO NPs) (<50 nm) and dissolved copper (CuCl 2). Uptake of NPs by benthic invertebrates that serve as food for higher trophic level organisms such as fish may result in their transfer along the food chain. Man-made nanoparticles (NPs) released into the aquatic environment are likely to accumulate in sediment.
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