Pollution with plastic is a growing concern in the marine
environment.1 However, emissions from land-based sources
reach rivers first, and freshwaters provide an important source
of marine plastic pollution through riverine transport.2
Therefore, the occurrence of plastic in the freshwater
environment receives increasing attention.3−6 Special concerns
exist with respect to nanoplastics because of their large surface
area and hypothesized ability to penetrate cells.7−11 Both
primary particles from personal care and cosmetic products and
secondary particles from degradation of larger plastic items are
expected to contribute to pollution of the environment with
nanoplastic.12 Recent reports showed the importance of
physical abrasion as a source of secondary micro- and
nanoplastic.13,14 Yet there are hardly any proven life history
effects of micro- and nanoplastic on marine organisms, and
effect data for freshwater organisms are lacking. For microplastic,
the first reported data on effects on invertebrates relate
to survival, feeding, oxidative status, and PCB uptake in
lugworms (Arenicola marina).15−17 In marine zooplankton,
decreased feeding18 and reduced survival and fecundity have
been observed.19 Even less is known about the effects of
nanoplastic. For mussels (Mytilus edulis),