Microplastic consumption and physiological response in Acartia clausi and Centropages typicus: Possible roles of feeding mechanisms

Abstract

Multi-day experiments were carried out with two Marmara Sea calanoid copepod species: Acartiaclausi and Centropages typicus, to assess the possible role of the type of feeding on the consumptionof microplastics and its influence on the rate of energy metabolism of these species. In a mixture ofmicroplastic beads (6 μm diameter) and algae Rhodomonas salina (5–10 μm size range) with equalconcentrations of about 5000 cells/beads mL −1 the ambush feeder A. clausi consumed almost 5 timesless microplastic 858.8 ± 294.1 beads ind−1 day−1 than the cruising feeder C. typicus and halved itsconsumption of microplastics alone, while C. typicus, on the contrary, increased its consumption rateof pure microplastics to 20237.4 ± 7020.41 beads ind−1 day−1. Both types of reaction to microplasticslead to a decrease in the respiratory rates of the copepods. During the 5 days of maintenance ona solely microplastic diet, the respiration rates of A. clausi and C. typicus decreased 2.2 and 3.4times, respectively, due to a decrease in the energy spent on motor activity, whilst maintaining basalmetabolic energy. It has been shown that in A. clausi, consuming microplastics, a decrease in respirationrate occurs in the same way as in individuals starving in filtered water. A more rapid respiration ratedecrease in Centropages typicus consuming microplastics may be due to the greater energy expenditureon microplastic beads capture and egestion via fecal pellets. Acartia clausi seems to exhibit a betterstrategy in dealing with the adverse consequences of microplastics consumption in comparison toCentropages typicus.