Fig 1.
Schematic map of study area and main current systems in the Nordic Seas.
White star indicates the crater area where plankton tows, box-cores and water sampling were conducted, detailed bathymetry can be found in Ofstad et al. [30]. Red lines are Atlantic Water inflows, blue line is Arctic Water outflows, and the green line is a coastal current. Abbreviations: NwAC Norwegian Atlantic current, WSC West Spitsbergen current, ESC East Spitsbergen current, NCC Norwegian Coastal Current. Current systems are based on Loeng [3]. Basemap from IBCAO 3.0 [51].
Fig 2.
Box-and-whisker plot of shell density with water depth for A) Neogloboquadrina pachyderma (n = 120), B) Turborotalita quinqueloba (n = 115) and c) Limacina helicina (n = 25) sampled from the crater area in 2016. Boxes extend from the lower to upper quartile values of the data, with a line at the median. Whiskers indicate 1.5 times the inter-quartile distance. Black dots are single measurements.
Fig 3.
Turborotalita quinqueloba from water column.
A) Texture of test surface of Turborotalita quinqueloba at three different depth intervals; 0–50 m, 100–150 m and 200–300 m. B) Variation in inner and outer shell density of T. quinqueloba as mean CT number of entire shell measured by XMCT increases. C) Mean CT number of T. quinqueloba (n = 115), with error bars, plotted against water depth. D) Calcite saturation at sampling site plotted against water depth. E) T. quinqueloba cross-section before and after assumed gametogenesis. Scale bars measure 100 μm.
Fig 4.
Neogloboquadrina pachyderma from water column.
A) Texture of test surface of Neogloboquadrina pachyderma at four different depth intervals; 0–50 m, 50–100 m, 100–150 m and 200–300 m. B) Variation in inner and outer shell density of N. pachyderma with mean CT number of entire shell measured by XMCT. C) Mean CT number of N. pachyderma (n = 120), with error bars, plotted against water depth and calcite saturation. D) Calcite saturation at sampling site plotted against water depth. Scale bars measure 100 μm.
Fig 5.
Shell thickness versus shell density.
Mean shell thickness of A) Neogloboquadrina pachyderma and B) Turborotalita quinqueloba plotted versus mean shell density in the form of a CT number, fitted with an exponential model. Shells from water column samples are represented by circles, while crosses represent shells from surface sediments. Exponential model is only fitted to shells from water column. Arrow in B) is pointing to an outlier.
Fig 6.
Turborotalita quinqueloba from surface sediments.
Cross-sections of Turborotalita quinqueloba specimens (A,C,D,E) from surface sediment sample (0–1 cm), including surface texture of a B) high-density (n = 11) and a F) low-density specimen (n = 7). Scale bars measure 100 μm.
Fig 7.
Neogloboquadrina pachyderma from surface sediments.
Cross-sections of Neogloboquadrina pachyderma specimens (A,C,D,E,F) from surface sediment sample (0–1 cm), including surface texture of a B) high-density (n = 3) and a G) low-density specimen (n = 9). F) Close-up of shell wall cross-section. Scale bars measure 100 μm.
Fig 8.
Limacina helicina from water column.
A) Limacina helicina shell diameter (n = 175) and density (n = 25) (given by CT number) with depth. B) Aragonite saturation at sampling site plotted against water depth. C) Generalized shell size with depth (left) and cross-sections of L. helicina specimens from 0–50 m (2 whorls), and 150–200 m (2.75 whorls) water depth interval. Grey boxes are shown as close-ups in E. D) Boxplot of Mann-Whitney U test on top shell thickness of L. helicina as a function of whorl number. E) Top of L. helicina specimens shown in C, schematic of shell thickness measurements performed on all shells. Scale bars measure 100 μm.