Exposure to microplastics can cause stress-induced spawning on arctic copepods

, Rodriguez Torres Rocío, Almeda Rodrigo, Kristiansen Michael, Rist Sinja, Winding Mie S., Nielsen Torkel G..

The Arctic is composed of sensitive ecosystems that are currently experiencing enormous changes. Knowledge about the effects of microplastic pollution on the arctic ecosystems is still scarce despite the extremely high concentrations of microplastics (MPs) currently found in arctic sea ice. We experimentally investigated the ingestion and impact of virgin MPs (20µm polyethylene spheres) on three key arctic copepods: Calanus finmarchicus, C. glacialis and C. hyperboreus. Copepod females were exposed to two MP concentrations (200 and 20000 MP L-1) in combination with different food concentrations (from 50 cells mL-1 to 5000 cells mL-1) for 6 days. We found that the three copepod species ingested MPs, up to 900 particles cop.-1 d-1. The amount of MPs inside the fecal pellets increased exponentially with decreasing food concentration. Fecal pellet production rates were not affected by the ingestion of MPs. However, egg production rate increased when copepods were exposed to MPs, suggesting that MPs causes stress-induced spawning. The presence of MPs inside the fecal pellets did not affect their sinking velocities. Overall, our results indicates that: (1) ingestion of virgin MP microspheres have a low impact on fecal pellet production rates of arctic Calanus species, (2) exposure to MPs can induce behavioral stress responses (e.g., increased spawning) and, (3) copepod fecal pellets may play a crucial role on the fate of virgin MP in the ocean by packing and vertically transporting the plankton-size particles to the sea floor.

View online