At the rainbow’s end: high productivity fueled by winter upwelling along an Arctic shelf

Abstract

Herein we document findings from a unique scientific expedition north of Svalbard in the middle of the polar night in January 2012, where we observed an ice edge north of 82°N coupled with pronounced upwelling. The area north of Svalbard has probably been ice-covered during winter in the period from approximately 1790 until the 1980s, a period during which heavy ice conditions have prevailed in the Barents Sea and Svalbard waters. However, recent winters have been characterized by midwinter open water conditions on the shelf, concomitant with northeasterly along-shelf winds in January 2012. The resulting northward Ekman transport resulted in a strong upwelling of Atlantic Water along the shelf. We suggest that a reduction in sea ice and the upwelling of nutrient-rich waters seen in the winter of 2012 created conditions similar to those that occurred during the peak of the European whaling period and that this combination of physical features was in fact the driving force behind the high primary and secondary production of diatoms and Calanus spp., which sustained the large historical stocks of bowhead whales (Balaena mysticetus) in Arctic waters near Spitsbergen.

Brief Communication: Trends in sea ice extent north of Svalbard and its impact on cold air outbreaks as observed in spring 2013

“…This especially holds for the Svalbard archipelago, which is close to the Fram Strait marginal sea ice zone. It has been shown by Ivanov et al (2012), Falk-Petersen et al (2014), and Onarheim et al (2014) that sea ice retreat is visible at the northern boundary of Svalbard by an increase of the "Whaler's Bay polynya" extent ( Fig. 1a).…”

Atlantic Water advection vs. glacier dynamics in northern Spitsbergen since early deglaciation

“…Today, easterlies are the prevailing winds at the northern margin of Svalbard (Lind and Ingvaldsen, 2012). Then, northward Ekman transport of surface waters generates (southward) upwelling of subsurface (or intermediate) AW, which subsequently is able to flood the northern shelf of Svalbard (Falk-Petersen et al, 2015;Lind and Ingvaldsen, 2012). A northward retreat of the sea ice edge even amplifies this mechanism (FalkPetersen et al, 2015, and references therein).…”

“…the shelves and fjords of Svalbard (Carmack and Wassmann, 2006). Therefore, the inflow of (sub)surface AW in the photic zone is interpreted as leading directly to a higher productivity (Carmack and Wassmann, 2006;Falk-Petersen et al, 2015;Sakshaug, 1997). Accordingly, nutrient advection and consequentially increasing phytoplankton blooms in spring and early summer may have resulted from such upwelling events during the early YD.…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…The input of nutrients to the Arctic Ocean basin by Arctic rivers is small (Le Fouest et al, 2013). Nutrient supply from the deep basins of the Arctic Ocean into the upper layers is restricted because of strong stratification , although in some shelf-slope areas, winter upwelling can fuel primary production (Falk-Petersen et al, 2015). Thus, horizontal advection is the main source of nutrients supporting new primary production in the Arctic.…”