Microplastics do not increase bioaccumulation of petroleum hydrocarbons in Arctic zooplankton but trigger feeding suppression under co-exposure conditions

Abstract

Arctic sea ice has alarmingly high concentrations of microplastics (MPs). Additionally, sea ice reduction in theArctic is opening new opportunities for the oil and maritime industries, which could increase oil pollution inthe region. Yet knowledge of the effects of co-exposure to MPs and crude oil on Arctic zooplankton is lacking.We tested the influence of MPs (polyethylene, 20.7μm) on polycyclic aromatic hydrocarbon (PAH)bioaccumulation and oil toxicity in the key arctic copepodCalanus hyperboreusafter exposure to oil with andwithout dispersant. Up to 30% of the copepods stopped feeding and fecal pellet production rates were reducedafter co-exposure to oil (1μLL−1) and MPs (20 MPs mL−1). The PAH body burden was ~3 times higher in feedingthan in non-feeding copepods. Copepods ingested both MPs and crude oil droplets. MPs did not influence bioac-cumulation of PAHs in copepods or their fecal pellets, but chemical dispersant increased bioaccumulation, espe-cially of≥4 ring-PAHs. Our results suggest that MPs do not act as vectors of PAHs in Arctic marine food webs afteroil spills, but, at high concentrations (20 MPs mL−1), MPs can trigger behavioral stress responses (e.g., feedingsuppression) to oil pollution in zooplankton.