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  • 1
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    Online Resource
    Multiproxy evidence of the Neoglacial expansion of Atlantic Water to eastern Svalbard
    Copernicus GmbH ; 2020
    In:  Climate of the Past Vol. 16, No. 2 ( 2020-03-10), p. 487-501
    Details
    In: Climate of the Past, Copernicus GmbH, Vol. 16, No. 2 ( 2020-03-10), p. 487-501
    Abstract: Abstract. The main goal of this study is to reconstruct the paleoceanographic development of Storfjorden during the Neoglacial (∼4 cal ka BP). Storfjorden is one of the most important brine factories in the European Arctic and is responsible for deepwater production. Moreover, it is a climate-sensitive area influenced by two contrasting water masses: warm and saline Atlantic Water (AW) and cold and fresh Arctic Water (ArW). Herein, a multiproxy approach was applied to provide evidence for existing interactions between the inflow of AW and sea ice coverage, which are the major drivers of environmental changes in Storfjorden. The sedimentary and microfossil records indicate that a major reorganization of oceanographic conditions in Storfjorden occurred at ∼2.7 cal ka BP. The cold conditions and the less pronounced presence of AW in Storfjorden during the early phase of the Neoglacial were the prerequisite conditions for the formation of extensive sea ice cover. The period after ∼2.7 cal ka BP was characterized by alternating short-term cooling and warming intervals. Warming was associated with pulsed inflows of AW and sea ice melting that stimulated phytoplankton blooms and organic matter supply to the bottom. The cold phases were characterized by heavy and densely packed sea ice, resulting in decreased productivity. The ancient environmental DNA (aDNA) records of foraminifera and diatoms support the occurrence of the major pulses of AW (∼2.3 and ∼1.7 cal ka BP) and the variations in sea ice cover. The episodes of enhanced AW inflow were marked by an increase in the percentage of DNA sequences of monothalamous foraminifera associated with the presence of fresh phytodetritus. Cold and less productive intervals were marked by an increased proportion of monothalamous taxa known only from environmental sequencing. The diatom aDNA record indicates that primary production was continuous during the Neoglacial, regardless of the sea ice conditions. However, the colder periods were characterized by the presence of diatom taxa associated with sea ice, whereas the present-day diatom assemblage is dominated by open-water taxa.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.5194/cp-16-487-2020
    DOI: 10.5194/cp-16-487-2020-supplement
    DOI: 10.5194/cp-16-487-2020-corrigendum
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2217985-9
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  • 2
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    The taxonomic status of the minute foraminifera 〈i〉Discorbina minutissima〈/i〉 Chaster (1892), 〈i〉D. chasteri〈/i〉 Heron-Allen & Earland (1913) and related species
    Copernicus GmbH ; 1992
    In:  Journal of Micropalaeontology Vol. 11, No. 2 ( 1992-12-01), p. 127-134
    Details
    In: Journal of Micropalaeontology, Copernicus GmbH, Vol. 11, No. 2 ( 1992-12-01), p. 127-134
    Abstract: Abstract. This study presents a revision, using type material, of the tiny foraminifera Discorbina minutissima Chaster, D. chasteri Heron-Allen & Earland (erected as a nomen novum for D. minutissima Chaster, non Seguenza) and D. chasteri var. bispinosa Heron-Allen & Earland. All are referred to the genus Rotaliella Grell. Heron-Allen & Earland’s new name chasteri is shown to be only applicable as a replacement name for Chaster’s species; their own material from Clare Island is a new species, named here R. heronalleni sp.nov. In addition, two other species — Rotaliella ? simplex (Sidebottom) and R. antarctica sp.nov. — have been recognised amongst the specimens labelled as D. chasteri in the Heron-Allen & Earland Collection in the Natural History Museum (BMNH). Lectotypes are designated for Rotaliella chasteri and R. bispinosa.
    Type of Medium: Online Resource
    ISSN: 2041-4978
    URL: Article
    DOI: 10.1144/jm.11.2.127
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 1992
    detail.hit.zdb_id: 2053393-7
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  • 3
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    Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology
    Copernicus GmbH ; 2017
    In:  Biogeosciences Vol. 14, No. 11 ( 2017-06-06), p. 2741-2754
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 14, No. 11 ( 2017-06-06), p. 2741-2754
    Abstract: Abstract. Deep-sea sediments constitute a unique archive of ocean change, fueled by a permanent rain of mineral and organic remains from the surface ocean. Until now, paleo-ecological analyses of this archive have been mostly based on information from taxa leaving fossils. In theory, environmental DNA (eDNA) in the sediment has the potential to provide information on non-fossilized taxa, allowing more comprehensive interpretations of the fossil record. Yet, the process controlling the transport and deposition of eDNA onto the sediment and the extent to which it preserves the features of past oceanic biota remains unknown. Planktonic foraminifera are the ideal taxa to allow an assessment of the eDNA signal modification during deposition because their fossils are well preserved in the sediment and their morphological taxonomy is documented by DNA barcodes. Specifically, we re-analyze foraminiferal-specific metabarcodes from 31 deep-sea sediment samples, which were shown to contain a small fraction of sequences from planktonic foraminifera. We confirm that the largest portion of the metabarcode originates from benthic bottom-dwelling foraminifera, representing the in situ community, but a small portion (〈 10 %) of the metabarcodes can be unambiguously assigned to planktonic taxa. These organisms live exclusively in the surface ocean and the recovered barcodes thus represent an allochthonous component deposited with the rain of organic remains from the surface ocean. We take advantage of the planktonic foraminifera portion of the metabarcodes to establish to what extent the structure of the surface ocean biota is preserved in sedimentary eDNA. We show that planktonic foraminifera DNA is preserved in a range of marine sediment types, the composition of the recovered eDNA metabarcode is replicable and that both the similarity structure and the diversity pattern are preserved. Our results suggest that sedimentary eDNA could preserve the ecological structure of the entire pelagic community, including non-fossilized taxa, thus opening new avenues for paleoceanographic and paleoecological studies.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-14-2741-2017
    DOI: 10.5194/bg-14-2741-2017-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
    detail.hit.zdb_id: 2158181-2
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  • 4
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    Online Resource
    Taxonomic relationships in the genus 〈i〉Ammonia〈/i〉 (Foraminifera) based on ribosomal DNA sequences
    Copernicus GmbH ; 2000
    In:  Journal of Micropalaeontology Vol. 19, No. 1 ( 2000-05-01), p. 85-95
    Details
    In: Journal of Micropalaeontology, Copernicus GmbH, Vol. 19, No. 1 ( 2000-05-01), p. 85-95
    Abstract: Abstract. The genus Ammonia is a common benthic foraminifer which is widely distributed in nearshore marine environments. Its large morphological variability causes considerable difficulties in species identification. In the present study, we investigated taxonomic relationships in Ammonia by using a molecular approach based on ribosomal DNA sequences. We obtained 149 partial large subunit ribosomal DNA (LSU rDNA) sequences and 23 small subunit ribosomal DNA (SSU rDNA) sequences from 88 living Ammonia specimens which were collected from free-living populations in 14 localities. Sequence analysis revealed the presence of eight distinct genotypic groups (T1–T7, T9) and one distinct genotype that is represented by one specimen (T8). Examination of morphological characters shows that only one genotypic group can be clearly distinguished by its morphology. Biogeographical and ecological features are used for an additional characterization and it seems that the different groups live in relatively well defined environmental conditions and that only one genotypic group is cosmopolitan, while the others have a rather restricted geographical distribution. According to our study, three of the genotypic groups can be regarded as distinct species.
    Type of Medium: Online Resource
    ISSN: 2041-4978
    URL: Article
    DOI: 10.1144/jm.19.1.85
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2000
    detail.hit.zdb_id: 2053393-7
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  • 5
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    Palaeoceanographic changes in Hornsund Fjord (Spitsbergen, Svalbard) over the last millennium: new insights from ancient DNA
    Copernicus GmbH ; 2016
    In:  Climate of the Past Vol. 12, No. 7 ( 2016-07-11), p. 1459-1472
    Details
    In: Climate of the Past, Copernicus GmbH, Vol. 12, No. 7 ( 2016-07-11), p. 1459-1472
    Abstract: Abstract. This paper presents a reconstruction of climate-driven environmental changes over the last millennium in Hornsund Fjord (Svalbard), based on sedimentological and micropalaeontological records. Our palaeo-investigation was supported by an analysis of foraminiferal ancient DNA (aDNA), focusing on the non-fossilized monothalamous species. The main climatic fluctuations during the last millennium were the Medieval Warm Period (MWP, AD 1000–1600), the Little Ice Age (LIA, AD 1600–1900) and the modern warming (MW, AD 1900 to present). Our study indicates that the environmental conditions in Hornsund during the MWP and the early LIA (before ∼ AD 1800) were relatively stable. The beginning of the LIA (∼ AD 1600) was poorly evidenced by the micropalaeontological record but was well marked in the aDNA data by an increased proportion of monothalamous foraminifera, especially Bathysiphon sp. The early LIA (∼ 1600 to ∼ AD 1800) was marked by an increase in the abundance of sequences of Hippocrepinella hirudinea and Cedhagenia saltatus. In the late LIA (after ∼ AD 1800), the conditions in the fjord became glacier-proximal and were characterized by increased meltwater outflows, high sedimentation and a high calving rate. This coincided with an increase in the percentages of sequences of Micrometula sp. and Vellaria pellucidus. During the MW, the major glacier fronts retreated rapidly to the inner bays, which limited the iceberg discharge to the fjord's centre and caused a shift in the foraminiferal community that was reflected in both the fossil and aDNA records. The palaeoceanographic changes in the Hornsund fjord over the last millennium were driven mainly by the inflow of shelf-originated water masses and glacial activity. However, the environmental changes were poorly evidenced in the micropalaeontological record, but they were well documented in our aDNA data. We considerably increased the number of potential proxy species by including monothalamous foraminifera in the palaeoecological studies.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.5194/cp-12-1459-2016
    DOI: 10.5194/cp-12-1459-2016-supplement
    DOI: 10.5194/cp-12-1459-2016-corrigendum
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
    detail.hit.zdb_id: 2217985-9
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