Timing of the active period for Calanus copepods in the Arctic

Retreating sea ice due to climate change creates opportunities for petroleum exploitation in historically inaccessible Arctic areas. However, Arctic ecosystems are considered particularly vulnerable to oil spills due to the remoteness, high seasonality of ecosystems, and low degradation rates of oil in polar regions. As petroleum activities move northward, potential oil spills may coincide with the short growth season of Arctic animals. Of particular importance are marine zooplankton in the genus Calanus, which dominate zooplankton biomass in Arctic and subarctic regions and play important roles as consumers of microplankton and prey for other animals, including commercially important fish stocks. In response to the highly seasonal environment at high latitudes, Calanus copepods perform seasonal vertical migrations. A short growth season is spent in upper waters, followed by an extended period dormant in deep waters. However, we have limited knowledge about the drivers behind the timing of the active period.

In this project, we will use three complementary approaches to investigate drivers behind the timing of the active period in Arctic Calanus. First, we will statistically analyze compiled pan-Arctic survey data to estimate the timing of the active phase across latitudinal gradients and identify potential environmental drivers. Secondly, we will perform laboratory experiments to investigate mechanisms behind the end of the active period. Finally, we will numerically model the optimal timing of the active period for different species and environmental conditions. Key questions we will address are how the timing of the active period of Calanus varies geographically and between years, and which mechanisms – including predation risk, food availability and abiotic factors – explain this variation. Results from this project can provide information on the seasonal variation in Arctic Calanus’ vulnerability to potential oil spills, and contribute towards a mechanistic understanding of the drivers behind seasonal migrations, a critical and elusive aspect of Calanus life history.

Figure: The zooplankton Calanus glacialis and other copepods of the genus Calanus play important roles as consumers of primary producers (phytoplankton) and prey for animals at higher trophic levels in Arctic and subarctic regions. Photo: Kristina Øie Kvile.

Relevant publications:

Kvile KØ, Ashjian C, Feng Z, Zhang J, Ji R. Pushing the limit: Resilience of an Arctic copepod to environmental fluctuations. Global Change Biology, https://doi.org/10.1111/gcb.14419.

Kvile KØ, Langangen Ø, Prokopchuk I, Stenseth NC, Stige LC. Disentangling the mechanisms behind climate effects on zooplankton. Proceedings of the National Academy of Sciences of the United States of America113:1841-1846

Kvile KØ, Dalpadado P, Orlova E, Stenseth NC, Stige LC. Temperature effects on Calanus finmarchicus vary in space, time and between developmental stages. Marine Ecology Progress Series 517:85-104