Alteration to organismal behavior due to microplastic exposure

Influx of plastics into the biosphere has faced increased public scrutiny in the last twenty years. Plastics fragment into particles at the microscale which can lead them to interact with organisms in unanticipated ways. Research has focused on hazards linked to ingestion of microplastics with little research focused on how secondary effects influence organismal behavior and interspecies relationships. Plastics do not establish homogenous test suspensions; they either float or sink. The present study investigated how the presence of microplastics influenced the behavior of Daphnia magna, and two planktivorous fish, Pimephales promelas and Gambusia affinis. The study investigated two plastic types: fluorescent microspheres and microplastic fragments. The results demonstrated that microplastics influenced the behavior of the organisms with effects dependent on species and plastic type. Microplastics attracted D. magna and decreased their mobility and total swimming distance. Both fish species were more often found at the bottom of the chamber and their behavior was linked to D. magna location. Some changes in fish mobility were observed with fluorescent microspheres. Coloration of microplastics may have influenced the organism's responses results and further research is needed. Results of the present study reveal a potential effect of microplastics on communal distribution of aquatic organisms in natural ecosystems.