Sea ice and primary production proxies in surface sediments from a High Arctic Greenland fjord: Spatial distribution and implications for palaeoenvironmental studies

Tage Dalsgaard,Thorbjørn Joest Andersen,Maija Heikkilä,Mikael K Sejr,Kaarina Weckström,Sofia Ribeiro,Marit-Solveig Seidenkrantz,Søren Rysgaard,Katrine Husum,Petra Tallberg,Guillaume Massé,Matthias Forwick,Audrey Limoges

doi:10.1007/s13280-016-0894-2

Abstract

In order to establish a baseline for proxy-based reconstructions for the Young Sound–Tyrolerfjord system (Northeast Greenland), we analysed the spatial distribution of primary production and sea ice proxies in surface sediments from the fjord, against monitoring data from the Greenland Ecosystem Monitoring Programme. Clear spatial gradients in organic carbon and biogenic silica contents reflected marine influence, nutrient availability and river-induced turbidity, in good agreement with in situ measurements. The sea ice proxy IP25 was detected at all sites but at low concentrations, indicating that IP25 records from fjords need to be carefully considered and not directly compared to marine settings. The sea ice-associated biomarker HBI III revealed an open-water signature, with highest concentrations near the mid-July ice edge. This proxy evaluation is an important step towards reliable palaeoenvironmental reconstructions that will, ultimately, contribute to better predictions for this High Arctic ecosystem in a warming climate.

Highlights

The thinning and retreat of Arctic sea ice is one of the most striking consequences of recent climate change, and has a very significant impact on Arctic ecosystem functioning (Wassmann et al 2011)
The BSi concentration in each sediment sample was inferred from the intercept of the linear regression equation obtained by plotting the increase in Si against time, assuming that all amorphous, biogenic Si had dissolved after 2 h of extraction, while mineral Si dissolved continuously at a constant rate during the 5-h extraction
Biogenic silica—a proxy for siliceous, mainly diatom production—was generally higher at the outer fjord stations and sites in the middle part of the ford, where there is a combination of high input from the glacial rivers, lower turbidity than in the innermost fjord region, and some degree of exchange with more saline and nutrient-rich waters from the outer fjord/Greenland Sea

Summary

Introduction

The thinning and retreat of Arctic sea ice is one of the most striking consequences of recent climate change, and has a very significant impact on Arctic ecosystem functioning (Wassmann et al 2011). Studies along the latitudinal gradient in sea ice cover around Greenland show a significant impact of sea ice on productivity of both primary (Krause-Jensen et al 2012) and secondary producers (Sejr et al 2009). This suggests that any future changes in sea ice cover will impact the marine ecosystem. Rysgaard and Glud 2007 and references therein) Today, this is one of the most studied High Arctic fjord systems in the world and can be considered a ‘‘natural laboratory’’

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