Seite - 167 - in Freshwater Microplastics - Emerging Environmental Contaminants?

Rist et al. [61]exposed themarineAsiangreenmusselPernaviridis to1–50μm polyvinyl chloride (PVC) fragments.MPexposure reduced thefiltrationand respi- ration rates, byssus production, aswell asmotility,whilemortalitywas enhanced. Regarding life-history parameters,MP significantly reduced the reproductive suc- cess ofCrassostrea gigas and negatively affected larval development of the off- spring(PSspheres,2,6μm).Sussarelluetal. [62] linkedtheseeffects toadisrupted energyuptake,which resulted in a shift of resources from reproduction to growth. In contrast, studies withM. edulis by van Cauwenberghe et al. [63] showed no significant effects of particle exposure to energy reserves (PS spheres, 10, 30, 90μm). Behavioral and physiological responses have also been shown for bivalves exposed to suspended solids. For instance, particle exposure damaged the cilia of the gill filaments inP. viridis (<500 μm[64]) and significantly reduced the algal ingestion ofM.mercenaria (3–40 μm, [65]). Therefore, the lack of studies com- paring impacts of bothMPs and suspended particles hampers a discrimination of MP-associated andmoregeneral particle-associated effects. Thesestudiesprovideevidence thatMPingestioncanaffectmarinebivalves.As thegeneral feeding strategies are consistent inbothmarineand freshwater species, the latter may be similarly affected. Still, morphological details of the feeding- associatedorgansvaryinthedifferentbivalvetaxa,whichcanalter feeding-specific characteristics [66]. 3.1.5 Gastropods Incomparison tobivalves, fewer studieshaveexaminedMPtoxicity ingastropods, which also have a high capacity to ingestMPs (discussed in Sect. 2.1). The only currently available study onMP toxicity in gastropods suggests limited impacts [36]. In this study, theomnivoroussurfacegrazerP.antipodarumwasexposed toa mixture of five different polymers (4.6–603 μm particle size; polyamide (PA), polycarbonate (PC), PET, PS, PVC) mixed with food at a ratio of 30 and 70%. After 8weeks,MPsneither affected the growth (shellwidth, length, bodyweight) nor the reproduction (number of produced embryos and ratio of embryoswith and without shell). Additionally,MP had no effect on the development of the conse- cutive generationof juveniles. 3.1.6 Fish Several adverse effects byMP exposures have also been observed for freshwater fishes (Table 2). MPs accumulate in the gills of marine crustaceans, and studies with freshwater fishes demonstrate that this pathway is relevant for vertebrate species too.Oneexample is zebrafish (Danio rerio) inwhichPSbeads accumulate Interactions ofMicroplasticswithFreshwaterBiota 167