The Effect of Exposure to Microplastic Particles on Baltic Sea Blue Mussel (Mytilus edulis) Filtration Rate

This study sought to investigate the effect of microplastics on Mytilus edulis’s ability to filtrate water. The mussels were sampled at Hanö bay located in the Baltic Sea, and were transported to a controlled environment. The mussels were exposed to three different solutions, one containing a concentration of 1 000 Microbeads (diameter 10 μm) per liter, one containing the same amount of plastic beads in addition to algae in a concentration of 3 000- 5 000 cells per ml, and the third group containing only algae. The mussels were kept in these different conditions for six days. After this acclimatization period the mussels were given filtrated salt water, and were all fed the same amount of algae during four hours. The number of algal cells per liter was counted every half hour, by removing a one ml sample and analyzing it using a FlowCam in order to test for any differences in filtration rate between the different groups. The study found that there was no significant difference in the net change in algal content between the groups, thus drawing the conclusion that microplastics in a concentration of 1000 beads per liter does not have a short-term effect on the filtration rate of the mussels. These results are discussed here to suggest that that the mussels are able to separate the microplastic into non-food particles before ingesting them. The results indicate that this process requires some amount of energy, which in turn make the mussels hungrier. This could have negative effects on the fitness of the mussels in the long-term, however the long term effects were not tested in this study. The study concludes that more research is needed.