All-sky camera system providing high temporal resolution annual time series of irradiance in the Arctic.

The ArcLight observatory provides hourly continuous time series of light regime data (intensity, spectral composition, and photoperiod) from the Arctic, Svalbard at 79° N. Until now, no complete annual time series of biologically relevant light has been provided from the high Arctic due to insufficient sensitivity of commercial light sensors during the Polar Night. We describe a camera system providing all-sky images and the corresponding integrated spectral irradiance () in energy or quanta units, throughout a complete annual cycle.

Artificial light during the polar night disrupts Arctic fish and zooplankton behaviour down to 200 m depth.

For organisms that remain active in one of the last undisturbed and pristine dark environments on the planet-the Arctic Polar Night-the moon, stars and aurora borealis may provide important cues to guide distribution and behaviours, including predator-prey interactions. With a changing climate and increased human activities in the Arctic, such natural light sources will in many places be masked by the much stronger illumination from artificial light. Here we show that normal working-light from a ship may disrupt fish and zooplankton behaviour down to at least 200 m depth across an area of >0.

Unexpected Levels of Biological Activity during the Polar Night Offer New Perspectives on a Warming Arctic.

The current understanding of Arctic ecosystems is deeply rooted in the classical view of a bottom-up controlled system with strong physical forcing and seasonality in primary-production regimes. Consequently, the Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply. Here, based upon a multidisciplinary ecosystem-scale study from the polar night at 79°N, we present an entirely different view.

Lipid sac area as a proxy for individual lipid content of arctic calanoid copepods.

We present an accurate, fast, simple and non-destructive photographic method to estimate wax ester and lipid content in single individuals of the calanoid copepod genus Calanus and test this method against gas-chromatographic lipid measurements.

Diel vertical migration of Arctic zooplankton during the polar night.

High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar night. One key process that is generally assumed to cease during winter is diel vertical migration (DVM) of zooplankton.