Bioaccumulation of oil compounds in the high-Arctic copepod Calanus hyperboreus

Oil and gas exploration in the Arctic will increase the risk for accidental oil spills and thereby have a potential impact on the ecosystem and the organisms inhabiting these areas. Lipid rich copepods are an important food source for higher trophic levels in Arctic marine ecosystems. However, high lipid content and a slower metabolism increase the risk for bioaccumulation in Arctic species. Here we exposed three late development stages of the lipid rich high-Arctic copepod species Calanus hyperboreus to two different ¹⁴C-marked crude oil model compounds, the alkane dodecane (log K_ow 6.10) and the polycyclic aromatic hydrocarbon (PAH) phenanthrene (log K_ow 4.46) on a short-term scale of 4days. Exposure was followed by a depuration phase of 3days. We observed a difference in estimated bioaccumulation of the two model compounds between stages and found a slower depuration of dodecane than of phenanthrene in the two largest and most lipid rich stages. However, depuration of dodecane and phenanthrene was non-significant for all three stages. The results indicate that even short-term exposure may result in long-term bioaccumulation and internal exposure of oil compounds in the lipid rich high-Arctic copepods C. hyperboreus. Slow elimination and depuration of oil components indicate a risk for transfer of oil component up the food web to pelagic fish, seabirds and baleen whales.