Competing effects of Atlantification and meltwater discharge on the productivity and burial of organic carbon off Kongsfjorden, Svalbard during the Holocene
Description
The unprecedented warming in the Arctic has altered the physiographic conditions resulting in contrasting variations in marine productivity. In the present study, we investigate the competing effects of enhanced warming, Atlantification and glacial melt on the productivity of an Arctic fjord (Kongsfjorden) in the western Svalbard margin during the Holocene (10.5 kyr BP). Productivity and preservation of organic matter have been reconstructed using multiple proxies, i.e. element and isotopic characterisation of sediment (Corg, Corg/N, 15N, TN, 13Corg), grain size and benthic foraminifera. The results suggest enhanced productivity but reduced preservation of organic carbon (Corg), dominated by regional influence for the early Holocene (10.5 – 7 kyr BP). In contrast, the mid-Holocene (7 – 4 kyr BP) was marked by strong nutrient utilisation and moderate marine productivity but with elevated preservation of organic carbon. The late Holocene was also less productive, albeit with few episodes of fluctuations in productivity. Moreover, the last ~200 years productivity variations are similar to those of modern-day patterns in the Kongsfjorden. With the ongoing rapid pace of warming, productivity is expected to increase despite large glacial meltwater discharge. A similar (or more intense) situation for productivity may be expected, as observed in the early Holocene. The present study helps in delineating the processes and vis-à-vis regional influences on the productivity variations, their preservation patterns and the eventual burial of organic matter in the fjordic sediments.