Biodiversity Data Journal : Research Article
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Research Article
Image dataset of benthic foraminifera in multicorer and gravity corer sediments from north-western Scotland shelf (North Atlantic Ocean)
expand article infoLiubov Kireenko, Anna Tikhonova, Nina Kozina, Alexander Matul
‡ Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
Open Access

Abstract

Geological studies in the seas and oceans often give preference to the study of benthic foraminifera, which are a widespread and taxonomically diverse group of shell protozoa. In this paper, we present an extensive image dataset produced during the detailed micropaleontological analysis of 146 samples of bottom sediments collected by multicorer and gravity corer AMK-5656 from the Westray Basin on the north-western Scotland shelf (North Atlantic Ocean). In total, 106 taxa (at species and genera level) of benthic foraminifera were identified and photographed using the high-resolution microscope camera. This dataset can aid as a guide for identification of the benthic foraminiferal taxa at the paleoecological studies, stratigraphic works and interregional paleoceanographic correlation in the North Atlantic Ocean.

Keywords

benthic foraminifera, micropaleontology, Scotland shelf, North Atlantic Ocean, Quaternary sediments

Introduction

The North Atlantic (NA) is one of the key areas of the thermohaline circulation system of currents that transfer the heat, salt, dissolved elements and gases and sedimentary matter to the Subarctic and Arctic regions. This circulation being a part of the large-scale circulation of the World Ocean affects the warming and cooling of the global climate and regional oceanography in the NA and Arctic (Morley et al. 2011). The climatic regime sets the marine environments, in particular, the habitat of the microorganisms which are preserved in the bottom sediments. An environmental imprint in the microfossil assemblages provides information on the modern and past oceanographic, climatic and ecological changes. Benthic foraminifers as calcareous microorganisms are one of the leading microfossil groups in the marine geological studies giving the appropriate biostratigraphic and paleoecological data.

In this article, we present a new extensive dataset of the microphotographic illustrations with taxonomic coverage for 106 benthic foraminiferal taxa (mostly as species and genera) from the latest Pleistocene to the the Holocene sediments in the Westray Basin on the north-western Scotland shelf (NWSS). The sediment material was collected in summer 2018 during the 71st cruise of the research vessel Akademic Mstislav Keldysh (Novigatsky et al. 2019). Laboratory treatment and microscopic analysis followed the standard micropaleontological technique for benthic foraminifera. We used the sediment fraction of > 63 μm to count small foraminiferal tests which can be numerous in the high-latitude sediments.

Previous studies described diverse and abundant benthic foraminiferal microfauna in the modern and the the Holocene sediments on and around the Scotland shelf and provided some microphotographs of the typical species (Lo Giudice Cappelli et al. 2019, Mackensen 1987, Mojtahid et al. 2021). Our aim is to continue a research study on the identification and illustration of the benthic foraminifera in the North Atlantic bottom sediments (Kireenko et al. 2022). We present 17 tables with high-quality microphotographs of 106 identified foraminiferal taxa (species and genera) produced using the Nikon microscope SMZ25, equipped with Nikon camera DS-Fi3 and NIS-Elements D software. This work intends to update existing guides on the benthic foraminifers from the European continental margin (like Murray 2003) potentially helping in the future routine micropaleontological studies in the area.

Data Description

We studied the benthic foraminiferal microfauna from the multicorer (MC) and gravity corer (GC) sediments on the AMK-5656 station obtained during the 71st cruise of the Russian research vessel Akademik Mstislav Keldysh in summer 2018 (Novigatsky et al. 2019). The location of the AMK-5656 station is the Westray Basin on the NWSS to the northwest of the Orkney Islands (59°29.469’ N, 3°49.783’ W; 157 m depth). The sediments of the MC (18 cm long) and GC (625 cm long) are the alternating foraminiferal light-brown sandy and muddy silts (Fig. 1).

Figure 1.  

Location of studied sediment cores AMK-5656 MC and GC. Map sources are GEBCO at https://download.gebco.net and EMODnet at https://portal.emodnet-bathymetry.eu.

The NWSS is a shallow water region of western North Atlantic Ocean dominated by the warm saline surface water of the North Atlantic Current branch crossing the NWSS from west to east between Orkney and Shetland (Anonymous 2022a). The cold deep water of Iceland-Scotland Overflow Current coming from the north via the Faroe-Iceland Channel can also influence the local bottom environments (Rasmussen et al. 2002, Sejrup et al. 2004). A prevailing sediment type in the Westray Basin is muddy sand or slightly gravelly sandy mud (Anonymous 2022b) which, in general, is similar to what we found in the AMK-5656 MC and GC.

Bio-monitoring studies, based on the living fauna, indicate that the taxonomically diverse benthic foraminifers densely populate the high-latitude shelf areas (Schönfeld et al. 2012). They sensitively react to environmental change and reflect the conditions occurring both at the bottom (factors of direct habitat on and in sediments) and the surface (e.g. phytoplankton production as food source) (Bauch et al. 2001).

Table 1 presents a list of the identified benthic foraminiferal species. We found in the samples of the AMK-5656 MC and GC, 106 taxa all in all identified mostly at species level, partly as genera. Amongst them, four species have the agglutinated shells and the rest are calcareous-secretive. The microphotographs on Figs 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 present high-resolution images of all identified benthic foraminifers showing the shell morphology of every taxa in details from two-three views (apertural, lateral, side, umbilical and spiral).

Table 1.

List of benthic foraminiferal taxa in station AMK-5656 from north-western Scotland shelf in North Atlantic.

Ammonia falsobeccarii (Rouvillois, 1974)

Amphicoryna scalaris (Batsch, 1791)

Amphicoryna separans (Brady, 1884)

Astrononion gallowayi Loeblich & Tappan, 1953 = Astrononion hamadaense Asano, 1950

Bolivina albatrossi Cushman, 1922

Bolivina earlandi Parr, 1950

Bolivina inflata Heron-Allen & Earland, 1913

Bolivina limbata (Brady, 1881) = Loxostomina limbata (Brady, 1881)

Bolivina pseudoplicata Heron-Allen & Earland, 1930

Bolivina spathulata (Williamson, 1858)

Bolivina striatula Cushman, 1922

Bolivina subspinescens Cushman, 1922

Bolivina tortuosa (Brady, 1881) = Sigmavirgulina tortuosa (Brady, 1881)

Bolivina sp. d'Orbigny, 1839

Bolivinellina pseudopunctata (Höglund, 1947)

Brizalina alata (Seguenza, 1862) = Bolivina alata (Seguenza, 1862)

Brizalina pygmaea (Brady, 1881) = Bolivina pygmaea (Brady, 1881)

Buccella frigida (Cushman, 1922) = Buccella calida (Cushman & Cole, 1930)

Bulimina aculeata d'Orbigny, 1826

Bulimina elongata d'Orbigny, 1846

Bulimina marginata d'Orbigny

Cassidulina carinata Silvestri, 1896

Cassidulina laevigata d'Orbigny, 1826

Cassidulina obtusa Williamson, 1858

Cassidulina reniforme Nørvang, 1945

Cassidulina teretis Tappan, 1951 = Cassidulina neoteretis Seidenkrantz, 1995

Cassidulina sp. d'Orbigny, 1826

Cassidulinoides bradyi (Norman, 1881)

Cornuspira involvens (Reuss, 1850)

Cibicides refulgens Montfort, 1808

Cibicides lobatulus (Walker & Jacob, 1798) = Lobatula lobatula (Walker & Jacob, 1798)

Cibicidoides wuellerstorfi (Schwager, 1866)

Cibicides sp. Montfort, 1808

Discorbis sp. Lamarck, 1804

Eggerelloides scaber (Williamson, 1858)

Elphidium clavatum Cushman, 1930 = Elphidium excavatum subsp. clavatum Cushman, 1930

Elphidium earlandi Cushman, 1936

Elphidium gerthi van Voorthuysen, 1957 = Cribroelphidium gerthi (van Voorthuysen, 1957)

Elphidium sp. Montfort, 1808

Epistomaroides polystomelloides (Parker & Jones, 1865)

Epistominella exigua (Brady, 1884)

Epistominella vitrea Parker, 1953 = Eilohedra vitrea (Parker, 1953)

Facetocochlea pulchra (Cushman, 1933)

Fissurina sp. Reuss, 1850

Fursenkoina fusiformis (Williamson, 1858) = Stainforthia fusiformis (Williamson, 1858)

Fursenkoina complanata (Egger, 1893) = Stainforthia loeblichi (Feyling-Hanssen, 1954)

Fursenkoina texturata (Brady, 1884)

Geminospira bradyi Bermúdez, 1952

Glabratella altispira Buzas, Smith & Beem, 1977

Globobulimina pacifica Cushman, 1927 = Laryngosigma lactea (Walker & Jacob, 1798)

Globocassidulina subglobosa (Brady, 1881)

Hyalinea balthica (Schröter, 1783)

Islandiella norcrossi (Cushman, 1933)

Lagena sp. Walker & Jacob, 1798

Lamarckina haliotidea (Heron-Allen & Earland, 1911)

Lenticulina gibba (d'Orbigny, 1839)

Massilina secans (d'Orbigny, 1826) = Quinqueloculina secans d'Orbigny, 1826

Melonis barleeanus (Williamson, 1858) = Melonis affinis (Reuss, 1851)

Melonis pompilioides (Fichtel & Moll, 1798)

Melonis sp. Montfort, 1808

Miliolinella subrotunda (Montagu, 1803)

Mychostomina revertens (Rhumbler, 1906)

Neoglabratella wiesneri (Parr, 1950)

Neolenticulina variabilis (Reuss, 1850)

Nonion pauperatum (Balkwill & Wright, 1885) = Subanomalina pauperata (Balkwill & Wright, 1885)

Nonion sp. Montfort, 1808

Nonionella auricula Heron-Allen & Earland, 1930

Nonionella iridea Heron-Allen & Earland, 1932

Nonionoides turgidus (Williamson, 1858)

Oolina sp. d'Orbigny, 1839

Patellina corrugata Williamson, 1858

Planorbulina mediterranensis d'Orbigny, 1826

Planulina sp. d'Orbigny, 1826

Procerolagena clavata (d'Orbigny, 1846)

Pyrgo murrhina (Schwager, 1866)

Pyrgo williamsoni (Silvestri, 1923)

Quinqueloculina seminulum (Linnaeus, 1758)

Quinqueloculina sp. d'Orbigny, 1826

Robertinoides bradyi (Cushman & Parker, 1936)

Robertinoides sp. Höglund, 1947

Rosalina araucana d'Orbigny, 1839 = Valvulineria araucana (d'Orbigny, 1839)

Rosalina auberii d'Orbigny, 1839 = Discorbis auberii (d'Orbigny, 1839) = Rotorbis auberii (d'Orbigny, 1839)

Rosalina bertheloti d'Orbigny, 1839 = Discorbinella bertheloti (d'Orbigny, 1839)

Rosalina bradyi (Cushman, 1915) = Rosalina anomala Terquem, 1875

Rosalina globularis d'Orbigny, 1826

Rosalina opercularis d'Orbigny, 1826 = Rosalina opercularis d'Orbigny, 1839 = Discorbina opercularis (d'Orbigny, 1839)

Rosalina vilardeboana d'Orbigny, 1839 = Discorbis vilardeboanus (d'Orbigny, 1839)

Rosalina sp. d'Orbigny, 1826

Sahulia conica (d'Orbigny, 1839) = Textularia conica d'Orbigny, 1839

Siphotextularia concava (Karrer, 1868)

Spiroloculina depressa d'Orbigny, 1826

Spiroloculina excavata d'Orbigny, 1846

Spiroloculina sp. d'Orbigny, 1826

Spirillina viviparina Saidova, 1975

Spiroplectinella wrighti (Silvestri, 1903)

Textularia sagittula Defrance, 1824

Triloculina elongata d'Orbigny in Fornasini, 1905

Triloculina trigonula (Lamarck, 1804)

Triloculina trihedra Loeblich & Tappan, 1953

Trifarina angulosa (Williamson, 1858)

Trifarina bradyi Cushman, 1923

Trifarina fluens (Todd in Cushman & McCulloch, 1948)

Uvigerina peregrina Cushman, 1923

Uvigerina mediterranea Hofker, 1932

Valvulineria minuta (Schubert, 1904) = Discorbis minuta (Schubert, 1904)

Valvulineria rugosa (d'Orbigny, 1839) = Discorbis rugosa (d'Orbigny, 1839) = Rosalina rugosa d'Orbigny, 1839

Figure 2.  

Station 5656 MC. 1 Brizalina pygmaea; 2 Brizalina alata, a,b lateral view; 3 Bolivina tortuosa; 4 Bulimina aculeata, a apertural view, b lateral view; 5 Bulimina marginata, a apertural view, b lateral view; 6 Bolivina pseudoplicata, 6a side view, 6b lateral view; 7 Bolivina pseudoplicata; 8,9 Bolivina earlandi, a side view, b lateral view; 10,11 Bolivina striatula, a side view, b lateral view. Scale 100 µm.

Figure 3.  

Station 5656 MC (continued). 12 Cassidulina carinata, a, b apertural view, c lateral view; 13 Cassidulina obtusa, a, b apertural view, c lateral view; 14 Cassidulina laevigata, a, b apertural view, c lateral view; 15 Cassidulina reniforme, a, b apertural view, c lateral view; 16 Cassidulina sp., cf. C. laevigata, a, b apertural view, c lateral view; 17 Cassidulina teretis, a, b apertural view, c lateral view; 18 Islandiella norcrossi, a, b apertural view, c lateral view; 19 Globocassidulina subglobosa, a side view, b apertural view, c lateral view. Scale 100 µm.

Figure 4.  

Station 5656 MC (continued). 20 Astrononion gallowayi, a side view, b apertural view, c lateral view; 21 Elphidium clavatum, a side view, b apertural view; 22 Elphidium earlandi, a side view, b apertural view, c lateral view; 23 Elphidium gerthi, a side view, b apertural view; 24 Nonionoides turgidus, a side view, b apertural view; 25 Nonionella iridea, a spiral view, b apertural view, c umbilical view; 26 Nonion pauperatum, a side view, b apertural view; 27 Nonionella auricula; 28 Nonion sp. cf. N. faba, a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 5.  

Station 5656 (continued). 29 Melonis barleeanus, a side view, b apertural view, c lateral view; 30 Melonis pompilioides, a side view, b apertural view; 31 Ammonia falsobeccarii, a spiral view, b apertural view, c umbilical view; 32 Hyalinea balthica, a side view, b apertural view; 33 Cibicides refulgens, a spiral view, b apertural view, c umbilical view; 34 Cibicides lobatulus, a spiral view, b apertural view, c umbilical view; 35 Epistomaroides polystomelloides, a side view, b apertural view; 36 Planulina ariminensis, a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 6.  

Station 5656 MC (continued). 37 Rosalina vilardeboana, a spiral view, b apertural view, c umbilical view; 38 Rosalina bradyi, a spiral view, b apertural view, c umbilical view; 39 Rosalina araucana, a spiral view, b apertural view, c umbilical view; 40 Rosalina auberii, a spiral view, b apertural view, c umbilical view; 41 Lamarckina haliotidea, a spiral view, b apertural view, c umbilical view; 42 Rosalina bertheloti, a spiral view, b apertural view, c umbilical view; 43 Rosalina opercularis, a spiral view, b apertural view, c umbilical view; 44 Rosalina globularis, a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 7.  

Station 5656 MC (continued). 45 Trifarina angulosa, a side view, b apertural view; 46 Trifarina bradyi, a side view, b apertural view; 47 Uvigerina mediterranea; 48 Uvigerina peregrina, a side view, b apertural view; 49 Fursenkoina fusiformis, a apertural view, b side view; 50 Fursenkoina complanata, a apertural view, b side view; 51 Geminospira bradyi, a apertural view, b side view; 52 Robertinoides sp., a side view, b lateral view; 53 Robertinoides bradyi, a apertural view, b side view; 54 Neolenticulina variabilis, a side view, b lateral view; 55 Lenticulina gibba; 56 Amphicoryna scalaris, a side view, b apertural view. Scale 100 µm.

Figure 8.  

Station 5656 MC (continued). 57 – 60 Fissurina sp.; 61,62 Lagena sp., a side view, b apertural view; 63 Oolina sp.; 64 Globobulimina pacifica, a side view, b apertural view; 65 Pyrgo williamsoni, a apertural view, b side view; 66 Quinqueloculina seminulum, a-c side view, d apertural view. Scale 100 µm.

Figure 9.  

Station 5656 MC (continued). 67 Miliolinella subrotunda, a side view, b apertural view, c lateral view; 68 Triloculina elongata, a side view, b apertural view; 69 Spiroloculina excavata, a, b side view, c apertural view; 70 Massilina secans, a, b side view, c apertural view; 71 Cornuspira involvens, a side view, b lateral view; 72 Epistominella exigua, a spiral view, b umbilical view; 73 Glabratella altispira, a spiral view, b umbilical view; 74 Patellina corrugate, a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 10.  

Station 5656 MC (continued). 75 Sp. cf. C. lobatulus juvenile test, a spiral view, b apertural view, c umbilical view; 76 Planorbulina mediterranensis, a spiral view, b umbilical view; 77 Discorbis sp., a spiral view, b apertural view, c umbilical view; 78 Sahulia conica, a apertural view, b side view; 79 Sahulia conica, a, c side view, b apertural view; 80 Textularia sagittula, a side view, b lateral view; 81 Siphotextularia concava, a side view, b lateral view; 82 Eggerelloides scaber, a, c side view, b apertural view. Scale 100 µm.

Figure 11.  

Station 5656 GC. 1 Brizalina pygmaea, a side view, b apertural view; 2 Brizalina alata, a, b side view, c apertural view; 3 Bolivina spathulata, a side view, b apertural view; 4 Bolivina striatula, a side view, b apertural view; 5 Bolivina pseudoplicata, a side view, b apertural view; 6 Bolivina earlandi, a side view, b lateral view; 7 Bolivinellina pseudopunctata, a side view, b apertural view; 8 Bolivina albatrossi, a side view, b apertural view; 9 Bolivina inflata, a side view, b apertural view; 10 Bolivina limbata, a side view, b lateral view; 11 Bolivina sp., a side view, b lateral view; 12 Bolivina subspinescens, a side view, b lateral view; 13,14 Fursenkoina complanata, 13a apertural view, 13b side view; 15 Fursenkoina fusiformis, a side view, b, c apertural view; 16 Fursenkoina texturata, a side view, b apertural view. Scale 100 µm.

Figure 12.  

Station 5656 GC (continued). 17 Bulimina marginata, a side view, b apertural view; 18 Bulimina elongata, a side view, b apertural view; 19 Bulimina aculeata, a side view, b apertural view; 20 Bulimina aculeata, a side view, b apertural view; 21 Trifarina angulosa, a side view, b apertural view; 22 Trifarina fluens, a side view, b apertural view; 23 Trifarina bradyi, a side view, b apertural view; 24 Uvigerina peregrina, a side view, b apertural view; 25 Uvigerina mediterranea, a side view, b apertural view; 26 Amphicoryna scalaris, a side view, b apertural view; 27 Amphicoryna separans, a side view, b apertural view; 28 Neolenticulina variabilis, a side view, b apertural view; 29 Lenticulina gibba, a side view, b apertural view. Scale 100 µm.

Figure 13.  

Station 5656 GC (continued). 30 Cassidulina carinata, a side view, b apertural view; 31 Cassidulina laevigata, a side view, b apertural view; 32 Cassidulina obtusa, a apertural view, b lateral view; 33 Cassidulina reniforme, a apertural view, b lateral view; 34 Cassidulina teretis, a side view, b apertural view; 35 Cassidulinoides bradyi, a side view, b apertural view; 36,37 Cassidulina sp. cf C. laevigata a side view, b apertural view; 38 Islandiella norcrossi, a side view, b apertural view; 39,40 Globocassidulina subglobosa, a side view, b apertural view; 41 Buccella frigida, a spiral view, b umbilical view; 42 Epistominella vitrea, a spiral view, b apertural view, c umbilical view; 43 Epistominella exigua, a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 14.  

Station 5656 GC (continued). 44,45 Rosalina vilardeboana, a spiral view, b apertural view, c umbilical view; 46 Rosalina globularis, a spiral view, b apertural view, c umbilical view; 47 Rosalina bradyi, a spiral view, b apertural view, c umbilical view; 48 Rosalina opercularis, a spiral view, b apertural view, c umbilical view; 49 Rosalina bertheloti, a spiral view, b apertural view, c umbilical view; 50 Rosalina araucana, a spiral view, b apertural view, c umbilical view; 51 Rosalina sp., a spiral view, b apertural view, c umbilical view; 52 Lamarckina haliotidea, a spiral view, b apertural view, c umbilical view; 53 Discorbis sp., a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 15.  

Station 5656 GC (continued). 54 Discorbis sp., a spiral view, b apertural view, c umbilical view; 55 Neoglabratella wiesneri, a spiral view, b apertural view, c umbilical view; 56 Cibicides lobatulus, a spiral view, b apertural view, c umbilical view; 57 Cibicidoides wuellerstorfi, a spiral view, b apertural view, c umbilical view; 58 Sp. cf. C. lobatulus juvenile test, a spiral view, b apertural view, c umbilical view; 59,60 Glabratella altispira, 59a spiral view, 59b umbilical view; 61 Patellina corrugata, a spiral view, b apertural view, c umbilical view; 62 Planorbulina mediterranensis, a spiral view, b umbilical view; 63 Valvulineria rugosa, a spiral view, b apertural view, c umbilical view; 64 Valvulineria minuta, a spiral view, b apertural view, c umbilical view. Scale 100 µm

Figure 16.  

Station 5656 GC (continued). 65 Elphidium clavatum, a side view, b apertural view; 66 Elphidium gerthi, a side view, b apertural view; 67 Elphidium sp. cf. E. magellanicum, a side view, b apertural view; 68 Elphidium earlandi, a side view, b apertural view; 69 Elphidium sp. cf. E. williamsoni, a side view, b apertural view; 70 Astrononion gallowayi, a side view, b apertural view; 71 Melonis pompilioides, a side view, b apertural view; 72 Melonis barleeanus, a side view, b apertural view; 73,74 Sp. cf. Haynesina depressula, a side view, b apertural view; 75 Ammonia falsobeccarii, a spiral view, b apertural view, c umbilical view; 76 Nonionella auricula; 77 Nonion pauperatum, a side view, b apertural view; 78 Nonionoides turgidus; 79 Nonionella iridea, a spiral view, b apertural view, c umbilical view. Scale 100 µm.

Figure 17.  

Station 5656 GC (continued). 80 Nonion sp., cf. N. faba, a spiral view, b apertural view, c umbilical view; 81,82 Robertinoides bradyi, a apertural view, b lateral view; 83 Geminospira bradyi, a apertural view, b lateral view; 84 Hyalinea balthica, a side view, b apertural view; 85 Sp.; 86 Mychostomina revertens, a spiral view, b apertural view, c umbilical view; 87 Spirillina viviparina, a spiral view, b apertural view, c umbilical view; 88 Cornuspira involvens, a side view, b apertural view; 89 Facetocochlea pulchra, a spiral view, b umbilical view; 90 Spiroloculina sp., a side view, b apertural view; 91 Spiroloculina depressa, a, b side view, c apertural view; 92 Globobulimina pacifica, a-c side view, d apertural view. Scale 100 µm.

Figure 18.  

Station 5656 GC (continued). 93 Pyrgo murrhina, a side view, b apertural view; 94 Pyrgo williamsoni, a side view, b apertural view; 95 Triloculina elongata, a side view, b apertural view; 96 Triloculina trigonula, a-c side view, d apertural view; 97 Triloculina trihedra, a, b side view, c apertural view; 98 Miliolinella subrotunda, a, b side view, c apertural view; 99 Massilina secans, a-c side view, d apertural view; 100 Quinqueloculina seminulum, a, b side view, c apertural view; 101 Quinqueloculina sp. cf. Q. seminulum; 102-106 Quinqueloculina sp. Scale 100 µm.

Figure 19.  

Station 5656GC (continued). 107-111 Fissurina sp.; 112,113 Lagena sp., a side view, b apertural view; 114 Procerolagena clavata, a side view, b apertural view; 115,116 Oolina sp. a side view, b apertural view; 117 Sp. cf. Asterorotalia pulchella, a, b side view; 118 Textularia sagittula, a, b side view, c apertural view; 119,120 Spiroplectinella wright, 119a, b side view, 119c apertural view, 120a side view, 120b apertural view; 121 Siphotextularia concava, a, b side view, b apertural view; 122,123 Sahulia conica, a side view, b apertural view. Scale 100 µm.

Studies of the radiocarbon dated sediment cores in Shetland-Orkney area of the NWSS (Bradwell et al. 2021) concluded that the ice-sheet withdrawal from the Westray Basin could occur just before 17.5 calendar ka. After this time level, we can expect starting marine sedimentation in the area. Therefore, our cores AMK-5656 MC and GC may contain records of the deglaciation and the Holocene. The radiocarbon datings on the AMK-5656 cores are not yet ready. There is a prominent change in the main parameters of the sedimentology, geochemistry and benthic foraminifera at the GC core level of 295 cm. Under the level: the content of terrigenous matter increases, CaCO3 content is between 25 and 40%, total abundance of benthic foraminifers is low and the infaunal shelf/slope species Bulimina marginata and Fursenkoina fusiformis have increased concentrations indicating the high fluxes of the total organic carbon and oxygen-depleted conditions (Alve 1994, Eichler et al. 2014). Above the level: opposite distribution of these parameters with a significant rise of CaCO3 and total foraminiferal content and sharp decline of the above-mentioned species abundance. Possible explanation of such change could be a transition from deglacial to the Holocene environments, but this will be proven by the radiocarbon dating.

Methods

Onboard, the retrieved MC and GC sediments were subsampled through every 1 cm and stored in the refrigerator. In the shore laboratory, we analysed 19 samples from the MC (every 1 cm) and 127 samples from the GC (every 5 cm). All samples were freeze-dried, weighed, washed in the distilled water through a sieve with mesh size of 63 µm as recommended in Fatela and Taborda 2002, Klootwijk and Alve 2022, dried and weighed again. We routinely counted 150-300 benthic foraminiferal tests per one sample under the microscope Nikon SMZ800N with a magnification of 80x. The microphotographs were made using the Nikon microscope SMZ25, equipped with Nikon camera DS-Fi3 and NIS-Elements D software. Then, microphotograph tables were edited by the computer software Adobe Photoshop CC 2019. To identify benthic foraminiferal taxa, we used publications by Feyling-Hanssen et al. 1971, Holbourn et al. 2013, Jones 1994, Tikhonova et al. 2019.

Usage notes

The microphotograph tables with images of benthic foraminifers can be used in the practical micropaleontological work with the modern and Quaternary sediment samples from the high-latitude areas of the North Atlantic. They will help the species identification, description of the foraminiferal assemblages and interpretation of the micropaleontological data for the biostratigraphy and paleoecology.

Acknowledgements

The authors thank the head of the expedition S.V. Gladyshev, the deputy head of the expedition A. N. Novigatsky, A. A. Klyuvitkin, S.M. Isachenko, G.V. Malafeev and the entire scientific staff for their assistance in conducting the expedition. The authors express special gratitude to the captain and crew of the research vessel Akademik Mstislav Keldysh.

Grant title

This work was funded by the Russian Foundation of Basic Research, project number 20-35-90093 and was carried out with partial support from the Russian Ministry of Education and Science, SIO theme No. 0128-2021-0006 (sediment sampling) and the Russian Science Foundation grant 21-17-00235 (micropaleontology).

Author contributions

Conceptualisation, L.K., A.T., N.K. and A.M.; Methodology, L.K.; Investigation, L.K. A.T. and N.K.; Resources, A.T. and N.K.; Data Curation, L.K.; Writing – Original Draft Preparation, L.K.; Writing – Review & Editing, A.T., N.K. and A.M; Visualisation, L.K.; Supervision, L.K.; Funding Acquisition, L.K. and A.M. All authors have read and agreed to the published version of the manuscript.

Conflicts of interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript or in the decision to publish the results.

References