Large-scale and long-time experiment testing the sensitivity of polar cod
Polar cod is a key component of Arctic marine food webs, connecting lower levels of the food web with those at the top by being an important food for sea birds and marine mammals. From a management perspective, it is therefore important to understand how sensitive polar cod is to potential pollution, which would provide us with an idea of the consequences an oil spill would have for the marine food web in the Arctic.
Recent research shows that polar cod eggs and larvae are sensitive to very low levels of crude oil. Adult polar cod, on the other hand, have been shown to efficiently break down toxic oil components and tolerate certain levels of oil exposure. However, in the event of an oil spill during the polar night, adult fish have depleted the majority of their energy reserves in order to produce good quality eggs and sperm, leaving little energy for the fish to combat the toxicity of oil compounds and withstand a major oil spill.
Nansen Legacy researchers are experimentally investigating the effects of crude oil exposure on polar cod in the spawning period during the Arctic winter. Illustration: Leah Strople
To test the effects of a winter oil spill on polar cod reproduction, Nansen Legacy postdoctoral fellow, Ireen Vieweg (UiT), brought many hundreds of live polar cod to Tromsø from a cruise in Hinlopen in 2018. In the aquarium facilities of UiT, the fish have been held in several large tanks under cold, dark and food deprived conditions since December, when they were exposed to low levels of crude oil. Since then, Nansen Legacy researchers have closely followed the fish’s physiological responses to the crude oil exposure, as well as their energy investment into reproduction. The experiment will run for five months and terminated around Easter.
Read more about the experiment on Forskning.no