Tire wear particle leachate exhibits trophic and multi-generational amplification: Potential threat to population viability.

The toxic additives leached from tire wear particles (TWPs) in road runoff can directly poison aquatic organism through high-dose exposure in sporadic hotspots. Given the ubiquity of road runoff carrying TWPs, it is necessary to assess whether there are lagging effects from low-dose exposure, as the toxicity of TWPs leachate can be transferred and amplified across multi-generations and different trophic levels: microalgae, zooplankton and larval fish. In this study, Chlorella pyrenoidesa exposed to different concentrations of TWPs leachate were fed to rotifer Brachionus calyciflorus, which were subsequently used as the initial feeding for fry of Cyprinus carpio. Below 1000 mg/L, the growth of microalgae was not influenced by TWPs leachate. Rotifer fed with contaminated microalgae for a single generation exhibited hormesis in their reproduction. After multigenerational feeding, the microalgae from 500 mg/L treatment were sufficient to suppress reproduction of rotifer since the third generation. For the secondary consumer carp fry, survival, growth, and feeding rate were significantly inhibited at first generation when consuming the rotifers fed with microalgae exposed to 250 mg/L TWPs leachate. So, evidence was presented for the generational and trophic amplification of toxicity in TWPs leachate within the food chain. A seemingly innocuous low dose can exhibit evident ecotoxicity after trophic and generational transfer, which could decline population viability of the aquatic organisms in the future.