Polovodova Asteman, Irina; Risebrobakken, Bjørg; Moros, Matthias; Binczewska, Anna; Dobosz, Slawomir; Jansen, Eystein; Slawinska, Joanna; Bak, Malgorzata (2017): Foraminifer, diatom frustules, and total organic carbon of sediment cores EMB046_6-5GC, EMB046_10-4GC, and EMB046_20-3GC in the Norwegian Trench and the Skagerrak [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.874853,

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Supplement to: Polovodova Asteman, I et al. (2018): Late Holocene palaeoproductivity changes: a multi-proxy study in the Norwegian Trench and the Skagerrak, North Sea. Boreas, 47(1), 238-255, https://doi.org/10.1111/bor.12264

To detect climatic linkages between the Baltic Sea, the Skagerrak and the Nordic Seas, we present multi‐proxy reconstructions covering the last 4500 years from three sediment cores taken in the Skagerrak and along the SW Norwegian margin. Foraminiferal assemblages at all three sites show a distinct change at c. 1700 years BP, associated with a transition from absence and rare occurrence of Brizalina skagerrakensis during c. 4500–2300 years BP to its subsequent abundance increase, suggesting a stronger influence of nutrient‐rich water‐masses during the last c. 1700 years. Increased nutrient availability, which probably stimulated higher primary productivity, is further supported by an increase in diatoms, total organic carbon and benthic foraminiferal species indicative of high productivity and carbon fluxes during the last c. 1700 years as compared to c. 4500–2300 years BP. The amplitude of the B. skagerrakensis signal is largest in the central Skagerrak and gradually becomes smaller towards the Norwegian Sea suggesting that the dominant source of the nutrient‐rich water was the brackish outflow from the Baltic Sea. The generally lower abundances of planktonic foraminifera since c. 1700 years BP support the hypothesis of less saline surface water conditions in the Skagerrak. These results agree with other studies, which suggest a stronger Baltic outflow over the last 1700 years coinciding with a general cooling, increased wintertime westerlies bringing more winter precipitation to northern Europe, increased river runoff and higher frequency of floods. The increase in outflow also occurs during deposition of laminated sediments in the deep Baltic Sea. Leakage of dissolved inorganic phosphorus from anoxic sediments, as well as enhanced erosion due to deforestation in combination with higher runoff from Norway, coastal upwelling and more vigorous frontal dynamics may all have contributed to higher nutrient availability within the adjacent Skagerrak during the last 1700 years BP as compared to c. 4500–2300 years BP, when low productivity prevailed in the study area.

The reconstruction of the late Holocene palaeoproductivity changes in the Skagerrak and the Norwegian Trench provides data of multiple proxies: benthic foraminifera, planktonic foraminifera, diatoms and total organic carbon (TOC) analyzed in 3 sediment cores: EMB046/6-5GC, EMB046/10-4GC and EMB046/20-3GC.

The data are given as nine files: 3 separate files (foraminifera, diatom and TOC) for each of the cores. Benthic foraminiferal data are presented as relative abundances (%) of Brizallina skagerrakensis and absolute abundances of palaeoproductivity species, low oxygen species, agglutinated taxa and total benthic foraminifera. Palaeoproductivity species include: Alabaminella weddelensis, Brizalina skagerrakensis, Bulimina marginata, Epistominella exigua, Epistominella vitrea, Nonionella iridea, Uvigerina mediterrannea and Uvigerina peregrina. Low oxygen species are grouped by summing together species Adercotryma glomerata, Ammodiscus spp., Bolivina spp., Buccella frigida, Globobulimina auriculata, Globobulimina turgida, Planulina ariminensis, Textularia earlandi, Spiroplectammina biformis and Stainforthia fusiformis.

Planktonic foraminifera and diatoms are given in absolute abundances per g sediment, whilst TOC data are in %.

The dataset has been originally published in:

Polovodova Asteman, I., Risebrobakken, B., Moros, M., Binczewska, A., Dobosz, S., Jansen, E., Slawinska, J., & Bak, M.: Late Holocene palaeoproductivity changes: a multi-proxy study in the Norwegian Trench and the Skagerrak, North Sea. Boreas.

This paper should be cited whenever the data are used.