Environmental changes in Krossfjorden, Svalbard, since 1950: Benthic foraminiferal and stable isotope evidence

Figures & data

Figure 1. (a) Overall map showing the location of Svalbard and the study area. (b) Bathymetric map showing the main surface currents, West Spitsbergen Current (WSC) and East Spitsbergen Current (ESC). (c) Bathymetric map of Krossfjorden showing the core site (green filled circle) and additional surface currents, Spitsbergen Polar Current (SPC) and Spitsbergen Trough Current (STC). Additionally, dashed purple line indicates the inflowing Atlantic Water (AW) to Krossfjorden at deep to intermediate water depths. White dashed line indicates the direction of meltwater from the glacier front.

Figure 2. Close-up of the inner part of Krossfjorden showing the site of NP16-Kro1-MC A and the glacier front positions of Lilliehöökbreen (König, Kohler, and Nuth 2013; Moholdt et al. 2021). Scale is indicated in the figure.

Figure 3. Temperature (red line) and salinity profile (blue line) from CTD (conductivity, temperature and density) cast carried out prior to coring, 2 August 2016 (Husum and Wold 2016).

Table 1. Time markers (core depth and age) used for developing depth–age model by Guruvayoorappan et al. (2020).

Core depth (cm)	Age Common Era
0	2016
22.5	1963
32.5	1954
Depth–age model
Core depth (cm)	Age Common Era (mean)	Sediment accumulation rate(cm/year)	Minimum age 68.2% confidence level	Maximum age 68.2% confidence level	Minimum age 95.4% confidence level	Maximum age 95.4% confidence level
2.5	2009	0.50	2005	2017	2003	2017
3.5	2007	0.50	2004	2012	1999	2017
4.5	2005	0.50	2001	2010	1998	2013
5.5	2003	0.50	1999	2008	1995	2012
6.5	2001	0.50	1997	2005	1992	2009
7.5	1999	0.33	1994	2004	1990	2007
8.5	1996	0.50	1993	2001	1988	2004
9.5	1994	0.50	1989	2000	1985	2003
10.5	1992	0.50	1987	1997	1984	2001
11.5	1990	0.33	1985	1995	1980	1999
12.5	1987	0.50	1983	1992	1979	1997
13.5	1985	0.50	1981	1990	1976	1994
14.5	1983	0.50	1978	1988	1974	1993
15.5	1981	0.50	1977	1986	1972	1989
16.5	1979	0.33	1974	1984	1970	1988
17.5	1976	0.50	1973	1980	1969	1985
18.5	1974	0.50	1969	1979	1966	1982
19.5	1972	0.50	1969	1975	1965	1980
20.5	1970	0.50	1965	1974	1963	1978
21.5	1968	0.33	1965	1972	1960	1974
22.5	1965	1.00	1964	1967	1962	1969
23.5	1964	1.00	1962	1966	1961	1968
24.5	1963	0.50	1961	1965	1959	1966
25.5	1961	1.00	1959	1963	1958	1965
26.5	1960	1.00	1958	1962	1956	1964
27.5	1959	0.50	1957	1961	1955	1963
28.5	1957	1.00	1955	1959	1954	1962
29.5	1956	1.00	1954	1958	1952	1960
30.5	1955		1953	1957	1951	1959

Note. Core depth, age including minimum and maximum ages (68.2 percent and 95.4 percent confidence level), and sediment accumulation rates are also shown (Guruvayoorappan et al. 2020).

Figure 4. Concentration (individuals * g⁻¹) and flux (individuals * cm⁻² * year⁻¹) of benthic foraminifera in core NP16-Kro1-MC A, percentage of calcareous and agglutinated forms, and diversity parameters. The shaded areas show the fauna assemblage zones identified by cluster analysis.

Figure 5. Stratigraphically constrained cluster analysis including all samples.

Figure 6. (a) Relative abundance (black line, upper x-axis) and flux (gray area, lower x-axis) of main calcareous species. The upper panel show species that constitutes a minimum of 2 percent of the fauna assemblage in at least two samples. The lower panel show species that constitutes a minimum of 1 percent of the fauna assemblage in at least two samples. The shaded areas show the fauna assemblage zones identified by cluster analysis. (b) Relative abundance (black line, upper x-axis) and flux (gray area, lower x-axis) of main agglutinated species that constitutes a minimum of 1 percent of the fauna assemblage in at least two samples. The shaded areas show the fauna assemblage zones identified by cluster analysis.

Figure 7. Stable isotope analysis (δ¹³C, δ¹⁸O) of NP16-Kro1-MC A. The shaded areas show the fauna assemblage zones identified by cluster analysis.

Figure 8. (a) Stable isotopes (δ¹³C, δ¹⁸O) from NP16-Kro1-MC A. (b) Temperature and salinity in the core of West Spitsbergen Current measured during late summer (Norwegian Polar Institute 2022a, 2022b). (c), (d) Selected benthic foraminiferal species (%) from NP16-Kro1-MC A. (e) Reconstructed SST (August) and MIZ diatoms (%) from Guruvayoorappan et al. (2020). The shaded areas show the fauna assemblage zones identified by cluster analysis.

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