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Bigler, Christian
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Myrstener, E., Biester, H., Bigler, C., Lidberg, W., Meyer-Jacob, C., Rydberg, J. & Bindler, R. (2019). Environmental footprint of small-scale, historical mining and metallurgy in the Swedish boreal forest landscape: The Moshyttan blast furnace as microcosm. The Holocene, 29(4), 578-591
Öppna denna publikation i ny flik eller fönster >>Environmental footprint of small-scale, historical mining and metallurgy in the Swedish boreal forest landscape: The Moshyttan blast furnace as microcosm
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2019 (Engelska)Ingår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 29, nr 4, s. 578-591Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The history of mining and smelting and the associated pollution have been documented using lake sediments for decades, but the broader ecological implications are not well studied. We analyzed sediment profiles covering the past similar to 10,000 years from three lakes associated with an iron blast furnace in central Sweden, as an example of the many small-scale furnaces with historical roots in the medieval period. With a focus on long-term lake-water quality, we analyzed multiple proxies including geochemistry, pollen and charcoal, diatom composition and inferred pH, biogenic silica (bSi), visible near-infrared spectroscopy (VNIRS)-inferred lake-water total organic carbon (LW-TOC), and VNIRS-inferred sediment chlorophyll (sed-Chl). All three lakes had stable conditions during the middle Holocene (similar to 5000 BCE to 1110 CE) typical of oligo-dystrophic lakes: pH 5.4-5.6, LW-TOC 15-18 mg L-1. The most important diatom taxa include, for example, Aulacoseira scalaris, Brachysira neoexilis, and Frustulia saxonica. From similar to 1150 CE, decreases in LW-TOC, bSi, and sed-Chl in all three lakes coincide with a suite of proxies indicating disturbance associated with local, small-scale agriculture, and the more widespread use of the landscape in the past (e.g. forest grazing, charcoal production). Most important was a decline in LW-TOC by 30-50% in the three lakes prior to the 20th century. In addition, the one lake (Fickeln) downstream of the smelter and main areas of cultivation experienced a shift in diatom composition (mainly increasing Asterionella formosa) and a 0.6 pH increase coinciding with increasing cereal pollen and signs of blast furnace activity. The pH did not change in the other two lakes in response to disturbance; however, these lakes show a slight increase (0.3-0.5 pH units) because of modern liming. LW-TOC has returned to background levels in the downstream lake and remains lower in the other two.

Ort, förlag, år, upplaga, sidor
Sage Publications, 2019
Nyckelord
diatoms, environmental change, geochemistry, human impacts, lake-water carbon, sediment, total organic carbon
Nationell ämneskategori
Ekologi
Identifikatorer
urn:nbn:se:umu:diva-158734 (URN)10.1177/0959683618824741 (DOI)000463639500004 ()
Tillgänglig från: 2019-05-21 Skapad: 2019-05-21 Senast uppdaterad: 2019-09-19Bibliografiskt granskad
Capo, E., Rydberg, J., Tolu, J., Domaizon, I., Debroas, D., Bindler, R. & Bigler, C. (2019). How Does Environmental Inter-annual Variability Shape Aquatic Microbial Communities?: A 40-Year Annual Record of Sedimentary DNA From a Boreal Lake (Nylandssjon, Sweden). Frontiers in Ecology and Evolution, 7, Article ID 245.
Öppna denna publikation i ny flik eller fönster >>How Does Environmental Inter-annual Variability Shape Aquatic Microbial Communities?: A 40-Year Annual Record of Sedimentary DNA From a Boreal Lake (Nylandssjon, Sweden)
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2019 (Engelska)Ingår i: Frontiers in Ecology and Evolution, E-ISSN 2296-701X, Vol. 7, artikel-id 245Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

To assess the sensitivity of lakes to anthropogenically-driven environmental changes (e.g., nutrient supply, climate change), it is necessary to first isolate the effects of between-year variability in weather conditions. This variability can strongly impact a lake's biological community especially in boreal and arctic areas where snow phenology play an important role in controlling the input of terrestrial matter to the lake. Identifying the importance of this inherent variability is difficult without time series that span at least several decades. Here, we applied a molecular approach (metabarcoding on eukaryotic 18S rRNA genes and qPCR on cyanobacterial 16S rRNA genes) to sedimentary DNA (sed-DNA) to unravel the annual variability of microbial community in 40 years' sediment record from the boreal lake Nylandssjon which preserve annually-laminated sediments. Our comparison between seasonal meteorological data, sediment inorganic geochemistry (X-ray fluorescence analyses) and organic biomarkers (pyrolysis-gas chromatography/mass spectrometry analyses), demonstrated that inter-annual variability strongly influence the sediment composition in Nylandssjon. Spring temperature, snow and ice phenology (e.g., the percentage of snow loss in spring, the timing of lake ice-off) were identified as important drivers for the inputs of terrestrial material to the lake, and were therefore also important for shaping the aquatic biological community. Main changes were detected in the late-80s/mid-90s and mid-2000s associated with increases in algal productivity, in total richness of the protistan community and in relative abundances of Chlorophyta, Dinophyceae as well as Cyanobacteria abundance. These changes could be linked to a decline in terrestrial inputs to the lake during the snow melt and run-off period, which in turn was driven by warmer winter temperatures. Even if our data shows that meteorological factors do affect the sediment composition and microbial communities, they only explain part of the variability. This is most likely a consequence of the high inter-annual variability in abiotic and biotic parameters highlighting the difficulty to draw firm conclusions concerning drivers of biological changes at an annual or sub-annual resolution even with the 40-year varved sediment record from Nylandssjon. Hence, it is necessary to have an even longer time perspective in order to reveal the full implications of climate change.

Ort, förlag, år, upplaga, sidor
Frontiers Media S.A., 2019
Nyckelord
varved sediment record, sedimentary DNA, protists, metabarcoding, meteorological data, inorganic geochemistry, organic proxies, paleolimnology
Nationell ämneskategori
Naturgeografi
Identifikatorer
urn:nbn:se:umu:diva-161823 (URN)10.3389/fevo.2019.00245 (DOI)000474916200001 ()
Tillgänglig från: 2019-08-12 Skapad: 2019-08-12 Senast uppdaterad: 2019-08-12Bibliografiskt granskad
Maier, D. B., Diehl, S. & Bigler, C. (2019). Interannual variation in seasonal diatom sedimentation reveals the importance of late winter processes and their timing for sediment signal formation. Limnology and Oceanography, 64(3), 1186-1199
Öppna denna publikation i ny flik eller fönster >>Interannual variation in seasonal diatom sedimentation reveals the importance of late winter processes and their timing for sediment signal formation
2019 (Engelska)Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, nr 3, s. 1186-1199Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Disentangling the process information contained in a diatom sediment signature is crucial for reliable future predictions based on paleolimnological records. In this study, we combine limnological and paleolimnological monitoring to address the fundamental question: Which environmental information is contained in a diatom sediment signal? We compared annual diatom sequential sediment trap records with the diatom record of the annually varved lake sediment of Nylandssjon (northern Sweden) from three meteorologically different years (2012-2014). The seasonal patterns in diatom sedimentation were strikingly different in varve years 2012 and 2014 compared to varve year 2013. In 2012 and 2014, up to 70% of the annual flux occurred in a single spring month and was dominated by Cyclotella glomerata. In contrast, in 2013, peak fluxes were much lower and more annually integrated. Next, we compared the full-year diatom trap results with year round in-lake physical, chemical, and biological monitored parameters, as well as meteorological variables. Annual averages of environmental conditions did not explain the interannual variability in diatom sedimentation. Instead, the seasonality of diatom sedimentation was determined by the timing of the spring diatom bloom relative to lake over-turn in winters with warm vs. cold air temperature. With our combined limnological and paleolimnological monitoring approach, we find that an annual diatom signal can either contain primarily seasonal climate information from a short time period or be annually integrated. We synthesize our results in a novel conceptual model, which describes the response of sediment diatom signals to two distinct sequences of late-winter conditions.

Ort, förlag, år, upplaga, sidor
Association for the Science of Limnology and Oceanography, 2019
Nationell ämneskategori
Geologi Klimatforskning
Identifikatorer
urn:nbn:se:umu:diva-159614 (URN)10.1002/lno.11106 (DOI)000467593600022 ()
Tillgänglig från: 2019-06-17 Skapad: 2019-06-17 Senast uppdaterad: 2019-06-17Bibliografiskt granskad
Zale, R., Huang, Y.-T. -., Bigler, C., Wood, J. R., Dalén, L., Wang, X.-R., . . . Klaminder, J. (2018). Growth of plants on the Late Weichselian ice-sheet during Greenland interstadial-1?. Quaternary Science Reviews, 185, 222-229
Öppna denna publikation i ny flik eller fönster >>Growth of plants on the Late Weichselian ice-sheet during Greenland interstadial-1?
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2018 (Engelska)Ingår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 185, s. 222-229Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Unglaciated forelands and summits protruding from ice-sheets are commonly portrayed as areas where plants first establish at the end of glacial cycles. But is this prevailing view of ice-free refugia too simplistic? Here, we present findings suggesting that surface debris supported plant communities far beyond the rim of the Late Weichselian Ice-sheet during Greenland interstadial 1 (GI-1 or Bolling-Altered interstadial). We base our interpretations upon findings from terrigenous sediments largely resembling 'plant-trash' deposits in North America (known to form as vegetation established on stagnant ice became buried along with glacial debris during the deglaciation). In our studied deposit, we found macrofossils (N = 10) overlapping with the deglaciation period of the area (9.5-10 cal kyr BP) as well as samples (N = 2) with ages ranging between 12.9 and 13.3 cal kyr BP. The latter ages indicate growth of at least graminoids during the GI-1 interstadial when the site was near the geographic center of the degrading ice-sheet. We suggest that exposure of englacial material during GI-1 created patches of supraglacial debris capable of supporting vascular plants three millennia before deglaciation. The composition and resilience of this early plant community remain uncertain. Yet, the younger group of macrofossils, in combination with pollen and ancient DNA analyses of inclusions, imply that shrubs (Salix sp., Betula sp. and Ericaceae sp) and even tree species (Larix) were present in the debris during the final deglaciation stage. 

Ort, förlag, år, upplaga, sidor
Elsevier, 2018
Nyckelord
Holocene, Pleistocene, Glaciology, Paleolimnology, Scandinavia, Vegetation dynamics, MIS-3
Nationell ämneskategori
Geologi Naturgeografi
Identifikatorer
urn:nbn:se:umu:diva-148634 (URN)10.1016/j.quascirev.2018.02.005 (DOI)000428830400015 ()
Forskningsfinansiär
Knut och Alice Wallenbergs StiftelseCarl Tryggers stiftelse för vetenskaplig forskning
Tillgänglig från: 2018-06-26 Skapad: 2018-06-26 Senast uppdaterad: 2018-08-17Bibliografiskt granskad
Adolf, C., Wunderle, S., Colombaroli, D., Weber, H., Gobet, E., Heiri, O., . . . Tinner, W. (2018). The sedimentary and remote-sensing reflection of biomass burning in Europe. Global Ecology and Biogeography, 27(2), 199-212
Öppna denna publikation i ny flik eller fönster >>The sedimentary and remote-sensing reflection of biomass burning in Europe
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2018 (Engelska)Ingår i: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 27, nr 2, s. 199-212Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Aim: We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10-500 mu m) and macroscopic charcoal (MAC from sieves, particles > 100 mu m). Location: North-south and east-west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period: Lake sediments and MODIS active fire and burned area products were collected for the years 2012-2015. Methods: Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm(2)/year) and the MODIS-derived products to identify source areas of charcoal and the extent to which lake-sediment charcoal is linked to fire parameters across the continent. Results: Source area of sedimentary charcoal was estimated to a 40-km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel-type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS-derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions: MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles (> 600 mu m), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.

Ort, förlag, år, upplaga, sidor
WILEY, 2018
Nyckelord
calibration in space, fire ecology, fire regime, lake-sediment charcoal, MODIS, palaeoecology
Nationell ämneskategori
Skogsvetenskap
Identifikatorer
urn:nbn:se:umu:diva-144332 (URN)10.1111/geb.12682 (DOI)000422750700004 ()
Tillgänglig från: 2018-02-08 Skapad: 2018-02-08 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Maier, D. B., Gälman, V., Renberg, I. & Bigler, C. (2018). Using a decadal diatom sediment trap record to unravel seasonal processes important for the formation of the sedimentary diatom signal. Journal of Paleolimnology, 60(2), 133-152
Öppna denna publikation i ny flik eller fönster >>Using a decadal diatom sediment trap record to unravel seasonal processes important for the formation of the sedimentary diatom signal
2018 (Engelska)Ingår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 60, nr 2, s. 133-152Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Sediment trap studies and high frequency monitoring are of great importance to develop a deeper understanding of how seasonal environmental processes are imprinted in sediment signal formation. We collected whole year diatom assemblages from 2002 to 2014 with a sequential sediment trap from a varved boreal lake (Nylandssjon, Sweden) together with environmental and limnological parameters, and compared them with the corresponding diatom record of the annual laminated sediment. Our data set indicates a large year-to-year variability of diatom succession and abundance patterns, which is well reflected in the varved sediments. Specifically, Cyclotella glomerata dominated the annual sediment trap record (as well as in the corresponding sediment varves) in years with warmer air temperatures in March/April, and Asterionella formosa dominated the annual sediment assemblages as a consequence of years characterized by higher runoff before lake over-turn. Years succeeding forest clearance in the lake catchment showed marked increase in diatom and sediment flux. The DCA scores of the yearly diatom trap assemblages clearly resemble the lake's thermal structure, which indicates that the relative abundance of major taxa seems primarily controlled by the timing of seasonal environmental events, such as above-average winter air temperature and/or autumn runoff and the current thermal structure of the lake. The high seasonal variability between environmental drivers in combination with the physical limnology leaves us with several possible scenarios leading to either an A. formosa versus C. glomerata dominated annual diatom sediment signal. With this study we highlight that short-term environmental events and seasonal limnological conditions are of major importance for interpreting annual sediment signals.

Ort, förlag, år, upplaga, sidor
Springer, 2018
Nyckelord
Annual diatom flux, Sequential sediment trap, Varved lake sediments, Seasonal air temperature, Discharge, Catchment
Nationell ämneskategori
Geologi Ekologi
Identifikatorer
urn:nbn:se:umu:diva-150660 (URN)10.1007/s10933-018-0020-5 (DOI)000437128400003 ()2-s2.0-85042094692 (Scopus ID)
Tillgänglig från: 2018-08-28 Skapad: 2018-08-28 Senast uppdaterad: 2018-08-28Bibliografiskt granskad
Milan, M., Bigler, C., Tolotti, M. & Szeroczynska, K. (2017). Effects of long term nutrient and climate variability on subfossil Cladocera in a deep, subalpine lake (Lake Garda, northern Italy). Journal of Paleolimnology, 58(3), 335-351
Öppna denna publikation i ny flik eller fönster >>Effects of long term nutrient and climate variability on subfossil Cladocera in a deep, subalpine lake (Lake Garda, northern Italy)
2017 (Engelska)Ingår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 58, nr 3, s. 335-351Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Albeit subfossil Cladocera remains are considered as a reliable proxy for tracking historical lake development, they have been scarcely studied in large subalpine lakes south of the Alps. In this study, subfossil Cladocera remains from Lake Garda in northern Italy were analyzed to track the lake's environmental changes since the Middle Ages. One core was retrieved from the largest sub-basin of Lake Garda (Brenzone, 350 m deep) and two cores were retrieved from the profundal and littoral zone of the smaller lake sub-basin (Bardolino, 80 and 40 m deep, respectively). The species distribution of Cladocera remains in recent sediment layers was similar to that observed in contemporary water samples. The deepest sections of the three cores were characterized by species sensitive to water temperature, which suggest a key role of major climatic events in driving the lake response during the late Holocene. The most evident change in Cladocera assemblages in the studied cores was observed during the 1960s, when planktonic taxa such as Daphnia spp. and Bosmina spp. became dominant at the expense of littoral taxa. Despite the highly coherent general pattern of subfossil Cladocera, the cores showed a set of minor differences, which were attributed to different morphological and hydrological features of the two basins forming Lake Garda. Multivariate analysis revealed a clear relation of Cladocera to climate variability during periods of low lake nutrient levels (i.e. before the 1960s). This provides additional information on past ecological responses of Lake Garda, as contrast previous data from subfossil diatom and pigment analyses did not fully capture effects of climate change during the same period. Since the 1960s shifts in assemblage composition of Cladocera and diatoms were highly coherent, in response to nutrient increase and the following, less pronounced, decrease in nutrient concentrations. During the last five decades, the response of the Cladocera to climate variability appeared to be masked by nutrient change. This work points up the potential of the multi-proxy approach for disentangling the multifaceted biological responses to multiple environmental stressors in large and deep lakes.

Ort, förlag, år, upplaga, sidor
SPRINGER, 2017
Nyckelord
Cladocera, Paleoecology, Sediment, Climate change, Trophy, Lake Garda
Nationell ämneskategori
Geologi
Identifikatorer
urn:nbn:se:umu:diva-140029 (URN)10.1007/s10933-017-9981-z (DOI)000410483900005 ()
Tillgänglig från: 2017-10-02 Skapad: 2017-10-02 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Meyer-Jacob, C., Bindler, R., Bigler, C., Leng, M. J., Lowick, S. E. & Vogel, H. (2017). Regional Holocene climate and landscape changes recorded in the large subarctic lake Torneträsk, N Fennoscandia. Palaeogeography, Palaeoclimatology, Palaeoecology, 487, 1-14
Öppna denna publikation i ny flik eller fönster >>Regional Holocene climate and landscape changes recorded in the large subarctic lake Torneträsk, N Fennoscandia
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2017 (Engelska)Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 487, s. 1-14Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Understanding the response of sensitive Arctic and subarctic landscapes to climate change is essential to determine the risks of ongoing and projected climate warming. However, these responses will not be uniform in terms of timing and magnitude across the landscape because of site-specific differences in ecosystem susceptibility to climate forcing. Here we present a multi-proxy analysis of a sediment record from the 330-km2 lake Torneträsk to assess the sensitivity of the Fennoscandian subarctic landscape to climate change over the past ~ 9500 years. By comparing responses of this large-lake system to past climatic and environmental changes with those in small lakes in its catchment, we assessed when the magnitude of change was sufficient to affect an entire region rather than only specific sub-catchments that may be more sensitive to localized environmental changes such as, e.g., tree-line dynamics. Our results show three periods of regional landscape alteration with distinct change in sediment composition: i) landscape development following deglaciation and through the Holocene Thermal Maximum, ~ 9500–3400 cal yr BP; ii) increased soil erosion during the Little Ice Age (LIA); and iii) rapid change during the past century coincident with ongoing climate change. The gradual landscape development led to successive changes in the lake sediment composition over several millennia, whereas climate cooling during the late Holocene caused a rather abrupt shift occurring within ~ 100 years. However, this shift at the onset of the LIA (~ 750 cal yr BP) occurred > 2000 years later than the first indications for climate cooling recorded in small lakes in the Torneträsk catchment, suggesting that a critical ecosystem threshold was not crossed until the LIA. In contrast, the ongoing response to recent climate change was immediate, emphasizing the unprecedented scale of ongoing climate changes in subarctic Fennoscandia.

Ort, förlag, år, upplaga, sidor
Elsevier, 2017
Nyckelord
Inorganic geochemistry, Soil erosion, Climate change, Oxygen and silicon isotopes, Holocene, Scandinavia
Nationell ämneskategori
Geovetenskap och miljövetenskap
Identifikatorer
urn:nbn:se:umu:diva-111628 (URN)10.1016/j.palaeo.2017.08.001 (DOI)000414881100001 ()
Anmärkning

Originally published in thesis in manuscript form 2015 with the title "Holocene ecosystem ontogeny and element cycling in the subarctic catchment of lake Torneträsk, NW Sweden : large lake sensitivity to climate change" by authors Carsten Meyer-Jacob, Richard Bindler, Christian Bigler, Melanie J. Leng and Hendrik Vogel.

Tillgänglig från: 2015-11-18 Skapad: 2015-11-18 Senast uppdaterad: 2018-06-07Bibliografiskt granskad
Capo, E., Domaizon, I., Maier, D., Debroas, D. & Bigler, C. (2017). To what extent is the DNA of microbial eukaryotes modified during burying into lake sediments?: A repeat-coring approach on annually laminated sediments. Journal of Paleolimnology, 58(4), 479-495
Öppna denna publikation i ny flik eller fönster >>To what extent is the DNA of microbial eukaryotes modified during burying into lake sediments?: A repeat-coring approach on annually laminated sediments
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2017 (Engelska)Ingår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 58, nr 4, s. 479-495Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Paleogenetics provides a powerful framework to reconstruct the long-term temporal dynamics of various biological groups from aquatic sediments. However, validations are still required to ensure the authenticity of the molecular signal obtained from sedimentary DNA. Here, we investigated the effects of early diagenesis on the DNA signal from micro-eukaryotes preserved in sediments by comparing metabarcoding inventories obtained for two sediment cores sampled in 2007 and 2013 respectively. High-throughput sequencing (Illumina MiSeq) of sedimentary DNA was utilized to reconstruct the composition of microbial eukaryotic communities by targeting the V7 region of the 18S rDNA gene. No significant difference was detected between the molecular inventories obtained for the two cores both for total richness and diversity indices. Moreover, community structures obtained for the two cores were congruent as revealed by procrustean analysis. Though most of the eukaryotic groups showed no significant difference in terms of richness and relative proportion according to the core, the group of fungi was found to differ both in terms of richness and relative proportion (possibly due to their spatial heterogeneity and potential activity in sediments). Considering the OTUs level (i.e. Operational Taxonomic Units as a proxy of ecological species), our results showed that, for the older analyzed strata (age: 15-40 years), the composition and structure of communities were very similar for the two cores (except for fungi) and the DNA signal was considered stable. However, for the uppermost strata (age < 15 years), changes of moderate magnitude were detected in the relative abundance of few OTUs. Overall, this study points out that, in Nylandssjon sediments, early diagenesis did not induce marked modifications in the micro-eukaryotic DNA signal, thus opening new perspectives based on the analysis of eukaryotic sedimentary DNA to address scientific issues both in the domains of paleolimnology and microbial ecology. Because this study site is ideal for DNA preservation in sediment (quick sedimentation processes, no sediment resuspension, anoxic conditions at sediment-water interface), the generalization of our conclusions, in particular for less favorable sites, must be considered cautiously.

Ort, förlag, år, upplaga, sidor
Springer, 2017
Nyckelord
eDNA, Paleogenetics, Sediment, Metabarcoding, Plankton
Nationell ämneskategori
Mikrobiologi
Identifikatorer
urn:nbn:se:umu:diva-142229 (URN)10.1007/s10933-017-0005-9 (DOI)000414421600004 ()
Tillgänglig från: 2017-12-11 Skapad: 2017-12-11 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Arnqvist, P., Bigler, C., Renberg, I. & Sjöstedt de Luna, S. (2016). Functional clustering of varved lake sediment to reconstruct past seasonal climate. Environmental and Ecological Statistics, 23(4), 513-529
Öppna denna publikation i ny flik eller fönster >>Functional clustering of varved lake sediment to reconstruct past seasonal climate
2016 (Engelska)Ingår i: Environmental and Ecological Statistics, ISSN 1352-8505, E-ISSN 1573-3009, Vol. 23, nr 4, s. 513-529Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Annually laminated (varved) lake sediments constitutes excellent environmental archives, and have the potential to play an important role for understanding past seasonal climate with their inherent annual time resolution and within-year seasonal patterns. We propose to use functional data analysis methods to extract the relevant information with respect to climate reconstruction from the rich but complex information in the varves, including the shapes of the seasonal patterns, the varying varve thickness, and the non-linear sediment accumulation rates. In particular we analyze varved sediment from lake Kassjon in northern Sweden, covering the past 6400 years. The properties of each varve reflect to a large extent weather conditions and internal biological processes in the lake the year that the varve was deposited. Functional clustering is used to group the seasonal patterns into different types, that can be associated with different weather conditions. The seasonal patterns were described by penalized splines and clustered by the k-means algorithm, after alignment. The observed (within-year) variability in the data was used to determine the degree of smoothing for the penalized spline approximations. The resulting clusters and their time dynamics show great potential for seasonal climate interpretation, in particular for winter climate changes.

Ort, förlag, år, upplaga, sidor
Springer, 2016
Nyckelord
Climate, Clustering, Curve registration, Functional data analysis, Penalized least squares, Varved lake diment
Nationell ämneskategori
Sannolikhetsteori och statistik Miljövetenskap
Identifikatorer
urn:nbn:se:umu:diva-130095 (URN)10.1007/s10651-016-0351-1 (DOI)000387424200002 ()
Tillgänglig från: 2017-01-13 Skapad: 2017-01-11 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
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