Interactions between vertical migration and local oceanography drive microplastic exposure for Antarctic krill

Euphausiids play important roles in ecosystems worldwide, transferring energy from primary producers to secondary consumers. Antarctic krill are the most abundant euphausiid on Earth and play important roles as critically important species in Southern Ocean ecosystems. Microplastics have been found throughout the Southern Ocean ecosystem, including krill. Here, we examine where krill and microplastics interact throughout the coastal ocean of the West Antarctic Peninsula. Using a physical ocean model to simulate the transport of vertically migrating krill and drifting microplastics, we identified several hotspots around the Antarctic Peninsula where both are consistently found in higher than average abundances. The extent of the overlap was modulated by both currents in the near-surface (< 50 m) and deep (> 50 m) ocean, and the vertical migration behaviors of Antarctic krill. Therefore, in order to understand the impacts of microplastics, we need to evaluate overlap in the context of euphausiid behavior and oceanographic conditions.