Natural variability of benthic foraminiferal assemblages and metal concentrations during the last 150 years in the Ingøydjupet trough, SW Barents Sea.

Abstract

While today the SW Barents Sea is a relatively un-impacted and uncontaminated area, industrial activities related to the petroleum industry are projected to increase in the coming decades. This makes the area a valuable natural laboratory to establish pre-impacted baselines as a precursor for future seabed monitoring programs. Here we present benthic foraminiferal assemblages and metal concentrations in four sediment cores from the Ingøydjupet trough, SW Barents Sea, covering approximately the last 150 years. This information supports the application of foraminiferal assemblages as a bio-monitoring tool applicable in high latitudes. At all stations, metal concentrations in the sediment correspond to no effect concentrations. The downcore metal concentrations are mainly attributed to natural variability of the clay fraction and total organic content of the sediments. Agglutinated foraminifera are poorly preserved down-core. Patterns in the calcareous foraminiferal assemblages suggest an enhanced food supply as a result of increased Atlantic Water inflow through the region during the last 150 years. At near-shore stations, the Norwegian Coastal Current additionally influences assemblages. Decadal scale climatic oscillations are indicated by increased calcareous fluxes and are attributed to variability in the food-rich Atlantic Water. This study serves as an important baseline data set prior to increasing industrial activities in the SW Barents Sea, and thereby contributes to a better understanding of natural environmental variability.