Data on the effects of different shapes of MP on biota are currently scarce. Thus, ESR9 will focus on the particle shape found in aquatic environments. Further, the shape of MP may interfere with uptake and gut retention time which in turn may alter their toxicity. ESR9 will expose freshwater key species to different shapes of MP from selected polymers to determine uptake, gut retention time and their toxicity. ESR9 will test the effects of different surface properties of biodegradable MP to investigate how degradation affects toxicity.