Impacts of Microplastics on Swimming Behavior of the Copepod Temora turbinata (Dana, 1849)

Zooplankton are vulnerable to the ingestion of microplastics by mistaking them for its prey. However, there is a lack of knowledge about the impacts of microplastic availability on zooplankton behavior. In this study, we investigated the effects of polystyrene microbeads on swimming patterns of the calanoid copepod Temora turbinata under controlled laboratory conditions. We acquired high-resolution video sequences using an optical system containing a telecentric lens and a digital camera with an acquisition rate of 20 frames per second. We estimated the mean speed, NGDR (Net-to-Gross Displacement Ratio, a dimensionless single-valued measure of straightness) and turning angle to describe the swimming behavior in three different treatments (control, low and high concentration of microplastics). Our results revealed that swimming speeds decreased by 30% (mean speed) to 40% (instantaneous speed). The NGDR and turning angle distribution of the organisms also changed in the presence of polystyrene microbeads. Such differences were more clearly observed at the high microplastic concentration (1,000 beads mL-1). These results suggest that the swimming behavior of Temora turbinata is affected by microbeads. Changes in copepod swimming behavior as a response to the presence of microplastics may lead to individual-based effects leading to potential impacts on several ecological traits, including bottom-up transference of microplastic particles to higher trophic levels.