Seasonal cycles are particularly strong in regulating many aspects of Arctic marine biology, particularly the timing of spring phytoplankton blooms and the ecosystem response in terms of both secondary production and coupling of these pelagic processes down to the benthos and up to birds and mammals. However, the vast majority of data on seasonality in Arctic trophic dynamics comes from studies in summer and autumn; far less is known for winter and spring periods, which severely limits understanding of Arctic marine ecosystems and their response to rapidly warming climatic conditions in this region. The classic assumption is that the pelagic realm in polar oceans, including zooplankton and micronekton, is essentially asleep during winter, waiting to awake in spring once light and phytoplankton return. However, several studies employing winter sampling have reported reproductively active holoplanktonic and meroplanktonic zooplankton populations in polynas and under sea ice, and zooplankton and micronekton in ice-covered and ice-free waters have recently been observed undergoing behaviors such as diel vertical migration, bioluminescence, and predatory feeding. This suggests that not only is there considerable biological activity at this time, but that light may be a significant ecological factor in the trophic interactions during polar winter. Our work is investigating pelagic biological processes in the polar winter to better understand the biological interactions at that time of year, and their implications for other seasons, now and under future climate change scenarios.
A major focus of our work is on pelagic bioluminescence in Arctic fjords of Svalbard. We are measuring bioluminescence of zooplankton and micronekton in the laboratory and in situ with bathyphotometers, along with optical properties of polar water, to develop algorithms that identify species based on flash kinetics. We are also studying the visual morphology and physiology of Arctic zooplankton and micronekton to develop numerical models for understanding ecological interactions mediated by vision in order to predict how they will be influenced by light availability and temperature in a warming Arctic. This work is allied with the Marine Night research program, and is funded through the Norwegian Research Council and the University Centre in Svalbard.
You can read more about a recent field expedition on UDaily.
Heather Cronin (UD Masters student), Jon Cohen, Mark Moline