Food transfer and uptake of nanosized polystyrene particles in a two-species marine system

Research has shown that smaller size plastic particles (<100nm) are available for biological uptake. Present study investigates the food transfer of polystyrene nanoparticles (50nm) in a maritime set up with Mytilus edulis and Carcinus maenas. Inspired by Dawson et al (2018), underlining the grinding function of krill to turn microplastic (MP) into nanoplastic (NP), the same two-species set-up was exposed to microplastic polystyrene particles (2μm) to investigate the internal fate of microplastics in C. maenas The study aims to assess the importance of food as source for plastic uptake and to what extend translocation occurr in both organisms. Seventy M. edulis were exposed through their diet to two concentrations, 0.167 mg/L and 1.67 mg/L, of polystyrene particles in two sizes, 2μm and 50nm. 35 females of C. maenas were fed one M. edulis apiece. Three tissue samples for the crabs and three for the mussels were analysed by fluorescent absorbance in an ELISA microplate reader. For the nanoplastic particles, we found a transfer from M. edulis to C. maenas for the high exposure treatment as well as for the low exposure treatment, however solely to the stomach tissue. The measurements for the microplastic particles suggested presence of titrated particles (<100nm) in the hepatopancreas. Notably, all p-values showed non-significance, which is likely because of the large background noise as seen in the control treatment. In the recent study by Schür et al (2019) the common methodology of uptake and translocation studies using fluorescent plastic particles is questioned. Results show that leaching of fluorescent dye occurs in lipid droplets in D. magna, and thus suggest artefacts in detection measurements. Further studies are needed to further explore the implications of our findings, e.g. detection confirmation by confocal microscopy.