MEPS 605:61-72 (2018)  -  DOI: https://doi.org/10.3354/meps12753

Pan-Arctic diel vertical migration during the polar night

L. Hobbs1,2,*, F. R. Cottier1,3, K. S. Last1, J. Berge3,4,5

1Scottish Association for Marine Science, Oban, Argyll PA37 1QA, UK
2Department of Mathematics and Statistics, University of Strathclyde, Glasgow G1 1XH, UK
3Department of Arctic and Marine Biology, UiT The Arctic University of Norway, 9037 Tromsø, Norway
4University Centre in Svalbard, 9171 Longyearbyen, Svalbard, Norway
5Centre for Autonomous Marine Operations and Systems, Norwegian University of Science and Technology, 7491 Trondheim, Norway
*Corresponding author:

ABSTRACT: Diel vertical migration (DVM) has generally been assumed to cease during the polar night in the high Arctic, although recent studies have shown the occurrence of lunar vertical migrations (LVMs) and shallow DVMs. Here, we quantified when and where full-depth (>20 m), solar-mediated DVM exists on a pan-Arctic scale. We observed the scattering population, most likely to be comprised of zooplankton, using 300 kHz acoustic Doppler current profilers (ADCPs). We quantified the presence/absence of DVM, and found that DVM continues throughout the year to at least 20 m at all locations south of 74°N. North of 77°N, DVM ceases for a period of time during the polar night. The dates of this cessation accurately align with the date of the winter solstice (±2 d). Between 74 and 77°N, DVM presence/absence is variable. Acoustic data sampled at 89°N, however, showed no evidence of DVM at any time during the year—a new observation. Using indicators of presence/absence of sea ice from ADCPs and satellite-derived sea ice concentration data, we revealed that local variations in sea ice cover directly determine the continuation or cessation of DVM during the polar night. Earlier-forming and higher-concentration sea ice causes a cessation in DVM, whereas low-concentration or late-forming sea ice results in continuous DVM when comparing migrations at similar latitudes.


KEY WORDS: Arctic · Diel vertical migration · Polar night


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Cite this article as: Hobbs L, Cottier FR, Last KS, Berge J (2018) Pan-Arctic diel vertical migration during the polar night. Mar Ecol Prog Ser 605:61-72. https://doi.org/10.3354/meps12753

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