Effects of crude oil and high salinity on eggs and early naupliar stages of the copepod <i>Calanus hyperboreus</i>

The rise in shipping due to the reduction of sea ice in the Arctic is expected to increase oil spill incidents. <i>Calanus hyperboreus</i> is a key organism in the Arctic food web and has a complex life cycle including pronounced seasonality and wide vertical distribution. Reproduction and spawning take place at depth in late winter, and the eggs float toward the surface, where they may encounter brine release and oil at the interface between water and sea ice. In the laboratory, we exposed <i>C. hyperboreus</i> eggs and nauplii to crude oil (1 μL L^-1) and high salinity (35.5 ppt), reflecting such conditions. Hatching success and nauplii size were not affected by exposure to oil alone, but decreased when exposed to high salinity or a combination of the two. The stressors did not impact the mortality of eggs and nauplii, which varied between 13.7% and 33.7% for the entire 6-day study period.