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  • 1
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    Multi-Sensor Analysis of the Spatial and Temporal Variability of Snow-Free Land Surface Albedo on Disko Island, Greenland
    In:  EPIC3
    Details
    Publication Date: 2024-04-30
    Description: Albedo – the reflectivity of a surface - is an important component in the energy budget, impacting the local to global climate. Data from nadir-viewing satellites can be combined with bidirectional reflectance distribution function (BRDF) data from multi-angular observation platforms to achieve realistic albedo values that acknowledge anisotropy. In my thesis, I evaluated how the land surface albedo varied on spatial and temporal scales during the snow-free period on Disko Island, Greenland. I examined how the albedo differed among the vegetation classes. Concerning the methodology, I assessed how the combination of MODIS BRDF data with Landsat 8 (L8) or Sentinel-2 (S2) influenced the albedo. The study area was located at the southern tip of Disko Island (69.27 °N, -53.47 °E) in West Greenland and covered a wetland and a range of tundra vegetation. I analysed automatic weather station (AWS) data from 2013 to 2022 and conducted mobile albedo measurements in August and September 2022 to examine the temporal and spatial variability. For the period from June to September 2022, I derived the L8 and S2 based albedo with inclusion of MODIS BRDF and narrow to broadband conversion and analysed their variability with regard to vegetation classes. In the snow-free period, the albedo increased from a monthly mean of 0.16 in June to 0.19 in September in the AWS data. The mobile measurements ranged from 〈 0.10 above bare soil and water to 〉 0.23 above areas dominated by lichen, Salix glauca or Equisetum arvense. The satellite-based albedo revealed temporally variable, significant correlations to normalised difference vegetation and moisture indices that reached values 〉 0.5 in the fen and wet heath class on several days. The albedo of shrubs was not notably smaller than other vegetation types but partly 0.01-0.05 above them in both the mobile measurements and the satellite-derived albedo. This finding challenges the assumption that shrubification causes climate forcing in all circumstances. The albedo of L8 and S2 differed to each other and the local data (root-mean-square error 0.04-0.14). The BRDF correction increased the albedo by 0.01 on average compared to nadir reflectance. L8 was better in reproducing the expected temporal and spatial variability of albedo than S2, which displayed less variability. S2 seemed to be more sensitive to atmospheric effects of haze and clouds influencing albedo. Thus, L8 seemed more suitable to calculate albedo in the study area. Though there were some methodological limitations, this thesis highlights aspects that should be considered when analysing albedo or jointly using L8 and S2 in high latitude regions.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Thesis , notRev
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  • 2
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    Cross-Chapter Paper 6: Polar Regions (2022)
    Cambridge University Press
    In:  EPIC3Climate Change 2022: Impacts, adaptation and vulnerability. Contribution of the WGII to the 6th assessment report of the intergovernmental panel on climate change, IPCC AR WGII, Cambridge University Press
    Details
    Publication Date: 2024-04-30
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 3
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    Loading Rate Variations Along a Midcrustal Shear Zone Preceding the M w 6.0 Earthquake of 24 August 2016 in Central Italy (2018)
    Details
    Publication Date: 2024-04-29
    Description: To identify greater detail in the seismicity pattern preceding the 24 August 2016 Mw6.0 earthquake in Central Italy, we apply waveform matching using 1,028 events as templates. In the 8 months before the mainshock, we find ~2,000 additional earthquakes mostly located along a subhorizontal shear zone (SZ) bounding at depth the extensional fault system. Asynchrony is observed in the occurrence of events nucleating along the SZ compared to the ones on fault portions embedded in the shallower upper crust, with the former anticipating the latter. Within the SZ, we also observe along-strike seismic migration episodes with earthquakes pointing toward the Mw6.0 mainshock nucleation zone. These episodes are followed by an apparent quiescence within the main fault area. We suggest that the variations in the seismic activity along the SZ represent the brittle signature of the tectonic loading process enabling portions of the overlaying normal faults to become unlocked.
    Description: Published
    Description: 12170–12180
    Description: 6T. Variazioni delle caratteristiche crostali e precursori
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Seismic Evidence of an Early Afterslip During the 2012 Sequence in Emilia (Italy) (2019)
    Details
    Publication Date: 2024-04-29
    Description: Earthquake interaction and stress change on nearby faults by afterslip, static and dynamic triggering play an important role in the activation of major events. We apply a matched filter technique to augment the detected events in the time window between the two main shocks of 20 (Mw 6.1) and 29 (Mw 6.0) May 2012, during the Emilia seismic sequence (Italy). From 1,727 well-located templates, we increase the number of detections to 7,616 lowering the completeness magnitude of approximately 0.6 degrees. This greater detail allows evidencing migrations of seismic events from the nucleation point of the first shock to the second. The seismicity pattern suggests a transient aseismic slip acting immediately after the shallow first event, weakening and loading the volume around the deep nucleation point of the 29 May 2012 Mw6.0 earthquake. Repeating earthquakes are also found between the two main-shocks. The released cumulative slip, estimated from the earliest repeating earthquake amounts to approximately 27 cm at a depth of about 7 km within the first 5 hours after the 20 May Mw6.1. Migrations and repeaters could represent the fingerprint of an early afterslip triggered by the first mainshock.
    Description: Published
    Description: 625-635
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    When the lava meets the sea: emplacement of the 2–4 ka San Bartolo lava flow field, Stromboli volcano (Italy) (2024)
    Springer
    Details
    Publication Date: 2024-04-29
    Description: When a lava flow enters a body of water, either a lake, sea, river or ocean, explosive interaction may arise. However, when it is an 'a'ā lava flow entering water, a more complex interaction occurs, that is very poorly described and documented in literature. In this paper, we analysed the 2–4 ka San Bartolo lava flow field emplaced on the north flank of Stromboli volcano, Italy. The lava flow field extends from ~ 650 m a.s.l. where the eruptive fissure is located, with two lava channels being apparent on the steep down to the coast. Along the coast the lava flow field expands to form a lava delta ~ 1 km wide characterised by 16 lava ‘Flow’ units. We performed a field survey to characterise the features of lava entering the sea and the associated formation of different components and magnetic measurements to infer the flow fabrics and emplacement process of the lava flow system. We measured the density, porosity and connectivity of several specimens to analyse the effect of lava-water interaction on the content in vesicles and their connectivity and conducted a macroscopic componentry analysis (clast count) at selected sites to infer the character of the eroded offshore segment of the lava flow field and its component flow units. The collected data allowed us to define the main components of a lava delta fed by 'a'ā lava flows, with its channels, littoral units, ramps, lava tubes, and inflated pāhoehoe flows controlled by the arterial 'a'ā flow fronts. The spatial organisation of these components allowed us to build a three-step descriptive model for 'a'ā entering a water. The initial stage corresponds to the entry of channel-fed 'a'ā lava flow into the sea which fragments to form metric blocks of 'a'ā lava. Continued lava supply to the foreshore causes flow units to stall while spreading over this substrate. Subsequent 'a'ā lava flow units ramp up behind the stalled flow front barrier. Lava tubes extending through the stalled flow barrier feed the seaward extension of a bench made of several pāhoehoe flow units.
    Description: Open access funding provided by Università degli Studi di Torino within the CRUI-CARE Agreement. This project is a part of RS PhD project. This research was funded by MIUR ex-60% attributed to EZ and PhD grants-Budget 10% attributed to RS. Also, it was partially funded by the Project FIRST (ForecastIng eRuptive activity at Stromboli volcano: Timing, eruptive style, size, intensity, and duration), INGV-Progetto Strategico Dipartimento Vulcani 2019 (Delibera n. 144/2020). This is contribution no. 637 of the ClerVolc program of the International Research Center for Disaster Sciences and Sustainable Development of the University of Clermont Auvergne.
    Description: Published
    Description: 50
    Description: OSV1: Verso la previsione dei fenomeni vulcanici pericolosi
    Description: JCR Journal
    Keywords: Stromboli volcano ; flank eruptions ; Lava flows
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Moho depths beneath the European Alps: a homogeneously processed map and receiver functions database (2023)
    Copernicus Publications
    Details
    Publication Date: 2024-04-29
    Description: We use seismic waveform data from the AlpArray Seismic Network and three other temporary seismic networks, to perform receiver function (RF) calculations and time−to−depth migration to update the knowledge of the Moho discontinuity beneath the broader European Alps. In particular, we set up a homogeneous processing scheme to compute RFs using the time-domain iterative deconvolution method and apply consistent quality control to yield 112,205 high-quality RFs. We then perform time−to−depth migration in a newly implemented 3D spherical coordinate system using a European-scale reference P and S wave velocity model. This approach, together with the dense data coverage, provide us with a 3D migrated volume, from which we present migrated profiles that reflect the first-order crustal thickness structure. We create a detailed Moho map by manually picking the discontinuity in a set of orthogonal profiles covering the entire area. We make the RF dataset, the software for the entire processing workflow, as well as the Moho map, openly available; these open-access datasets and results will allow other researchers to build on the current study.
    Description: Published
    Description: 2117–2138
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Continuous monitoring of surface water vapour isotopic compositions at Neumayer Station III, East Antarctica (2021)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 15(10), pp. 4745-4767, ISSN: 1994-0424
    Details
    Publication Date: 2024-04-29
    Description: In this study, the first fully continuous monitoring of water vapour isotopic composition at Neumayer Station III, Antarctica, during the 2-year period from February 2017 to January 2019 is presented. Seasonal and synoptic-scale variations in both stable water isotopes H182O and HDO are reported, and their links to variations in key meteorological variables are analysed. In addition, the diurnal cycle of isotope variations during the summer months (December and January 2017/18 and 2018/19) has been examined. Changes in local temperature and specific humidity are the main drivers for the variability in δ18O and δD in vapour at Neumayer Station III, on both seasonal and shorter timescales. In contrast to the measured δ18O and δD variations, no seasonal cycle in the Deuterium excess signal (d) in vapour is detected. However, a rather high uncertainty in measured d values especially in austral winter limits the confidence of this finding. Overall, the d signal shows a stronger inverse correlation with specific humidity than with temperature, and this inverse correlation between d and specific humidity is stronger for the cloudy-sky conditions than for clear-sky conditions during summertime. Back-trajectory simulations performed with the FLEXPART model show that seasonal and synoptic variations in δ18O and δD in vapour coincide with changes in the main sources of water vapour transported to Neumayer Station III. In general, moisture transport pathways from the east lead to higher temperatures and more enriched δ18O values in vapour, while weather situations with southerly winds lead to lower temperatures and more depleted δ18O values. However, on several occasions, δ18O variations linked to wind direction changes were observed, which were not accompanied by a corresponding temperature change. Comparing isotopic compositions of water vapour at Neumayer Station III and snow samples taken in the vicinity of the station reveals almost identical slopes, both for the δ18O–δD relation and for the temperature–δ18O relation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    Bericht aus dem AWI - 17. Nationales GCOS Treffen, 01.03.2023, Bremerhaven (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: Reporting for the German GCOS
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 9
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    How dynamic is the Greenland Ice Sheet? Insights from reconstructed paleo ice-stream activity in Northern Central Greenland. (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: Insights from reconstructed Holocene paleo ice-stream activity in Northern Central Greenland.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 10
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    Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream – CORRIGENDUM (2023)
    Cambridge University Press (CUP)
    In:  EPIC3Annals of Glaciology, Cambridge University Press (CUP), pp. 1-1, ISSN: 0260-3055
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 11
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    Monitoring of the polygonal reservoir of the Kytalyk reserve (Indigirka river) (2022)
    Limnological Institute SB RAS
    In:  EPIC3Limnology and Freshwater Biology, Limnological Institute SB RAS, 5(4), 3 p., pp. 1470-1472, ISSN: 2658-3518
    Details
    Publication Date: 2024-04-29
    Description: Diatom analysis is one of the methods of paleolimnological research, with the help of which it is possible to determine the state and development of aquatic ecosystems in the past and present. Assessment of the current state of reservoirs is of great importance in paleolimnology, it will allow to obtain results about temperature regime, mineralization, pH environment and water quality. The research area is a region with a lot of small polygonal reservoirs that react quickly enough to external environmental changes that are formed during the cracking of re-vein ice and may form large reservoirs in the future. In this work, the IP-1 monitoring reservoir of the Kytalyk locality was studied for 10 days (every three days) during the expedition work carried out in 2011 using standard methods and a set of field equipment. The material of the study was phytoplankton samples, as a result of which the taxonomic composition of the diatom flora was investigated and the water quality of the Kytalyk monitoring site located in the basin of the Berelyakh river, the left tributary of the Indigirka, was determined.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 12
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    Editorial: Yedoma Permafrost Landscapes as past Archives, Present and Future Change Areas (2022)
    Frontiers in Earth Science
    In:  EPIC3Frontiers in Earth Science, Frontiers in Earth Science, 10, 5 p., pp. 929873-929873, ISSN: 2296-6463
    Details
    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 13
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    Modelling the three-dimensional stratigraphy of an ice rise (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: The geometry of englacial isochrones is a product of the past and present ice velocity field and is useful for our understanding of steady-state ice flow dynamics, flow regime re-organisation, and calibration of models. Ice rises contain various flow regimes (divide flow, flank flow, and grounding zones) on small spatial scales, meaning they are ideal locations to study ice-flow dynamics and stratigraphy to constrain model parameters. We run full Stokes, thermo-mechanically coupled simulations of Derwael Ice Rise in East Antarctica and simulate the three-dimensional stratigraphy of the ice rise and the surrounding ice shelf using the finite element model Elmer/Ice. Over the ice rise, we derive the accumulation rate from internal reflection horizons and use RACMO2.3 surface mass balance data over the surrounding ice shelf. Simulations are run for Glen's flow law exponents of n=3 and n=4 with appropriate values derived for the Arrhenius law. To calibrate the model, comparisons are made with the BedMachine surface elevation and density-adjusted internal reflection horizons observed in many transects recorded by AWI’s ultra-wide band radar covering the divide, the flanks, and the grounding zones. To understand ice flow dynamics where the velocity field of the ice rise and the ice shelf converge in the compressive and shear zones, we analyse the modelled englacial stress and strain rate fields. Our results allow us to investigate isochronal structures where observed internal reflection horizons are too steep or obscured to be adequately picked up by radar. A comparison between the model and observed fracturing can be used to infer threshold stress and strain rates for fracture initiation. These simulations are a blueprint for the full Stokes, three-dimensional modelling of ice rises and have further relevance in the study of three-dimensional influences on Raymond arch evolution, the constrained coupling of the anisotropy equations, comparisons with ice core data and the automated inference of ice flow parameters from internal reflection horizons.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 14
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    Investigating firn and ice anisotropy around the EastGRIP Camp, North East Greenland Ice Stream, from ambient noise surface waves (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: We use cross-correlations of ambient seismic noise data between pairs of 9 broadband three component seismometers to investigate variations in velocity structure and anisotropy in the vicinity of the EastGRIP camp along and across flow of the Northeast Greenland Ice Stream (NEGIS). From the 9-component correlation tensors associated with all station pairs we derive dispersion curves of Rayleigh and Love wave group velocities between station pairs at frequencies from 1 to 25 Hz. The distributions of the Rayleigh and Love group velocities exhibit anisotropy variations for the along and across flow component. To better assess those variations, we invert the dispersions curves to shear wave velocities in the horizontal (Vsh) and vertical (Vsv) direction for the top 300 m of the NEGIS using a Markov Chain Monte Carlo approach. The reconstructed 1-D shear velocity model revels radial anisotropy in the NEGIS. Along and across flow vertical shear wave velocities (Vsv) identify comparable velocity profiles for all depths. However, horizontal shear wave velocities (Vsh) are faster by approximately 250 m/s in the along flow direction below a depth of 100 m, i.e. below the firn-ice transition. This type of anisotropy seems to arise from the alignment of a crystallographic preferred orientation, due to deformation associated with shear zones. The role of anisotropy as e.g. created by air bubbles in the firn and ice matrix, is yet unclear. Faster Vsh velocities in the along flow direction support that the NEGIS has crystal orientation alignment normal to the plane of shear compression (i.e. ice crystals orientated across flow) within the upper 300 m of the ice stream and are in alignment with the results from other methods. We demonstrate that simple, short duration (2-3 weeks), passive seismic deployment and environmental noise-based analysis can be used to determine the anisotropy of the upper part of ice masses.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 15
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    Lessons learned from past aerogeophysical collaborations for effectively launching new pan-Antarctic RINGS surveys
    In:  EPIC3Proceedings of the COMNAP Symposium 2023 Antarctic Innovations and Collaborations, Council of Managers of National Antarctic Programs
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 16
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    Ice-ocean interactions at Riiser-Larsen Ice Shelf assessed by unveiling of seabed beneath it (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: The Riiser-Larsen ice shelf is the fourth largest ice shelf on Earth. The detailed depth and shape of the seabed beneath the ice shelf is entirely unknown. Since bed topography beneath ice shelves generally poses the controlling factor of heat exchange between the open ocean and water cavities, this unknown factor inhibits proper assessment of ice-ocean interactions. In coastal Dronning Maud Land, the intrusion of Warm Deep Water – a warm intermediate water mass transported by the Weddell Gyre – into the ice shelf cavities is strongly dependent on seabed depth. We are addressing this shortcoming by generating a bathymetric model beneath the ice shelf based on the inversion of gravity data and complementary data sets of magnetic and ice penetrating radar data, all acquired during the joint AWI-BGR airborne campaign ‘RIISERBATHY’ in 2022/23. The resulting model will have a resolution of 5 to 10 km and is complemented offshore by shipborne hydroacoustic data. We present the first versions of the model here. Modelled depths can be compared to thermocline depths of available in-situ oceanographic data close to and at the calving fronts. In doing so, we will identify key regions of possible entry for Warm Deep Water into the cavity beneath the ice shelf.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 17
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    Correction to “A Statistical Test of Phase Closure to Detect Influences on DInSAR Deformation Estimates Besides Displacements and Decorrelation Noise: Two Case Studies in High-Latitude Regions” (2019)
    Institute of Electrical and Electronics Engineers (IEEE)
    In:  EPIC3IEEE Transactions on Geoscience and Remote Sensing, Institute of Electrical and Electronics Engineers (IEEE), 57(1), pp. 623-623, ISSN: 0196-2892
    Details
    Publication Date: 2024-04-29
    Description: There was a typographical error in [1, eq. (18)]. Instead of (Formula Presented). The equation describes the second-order statistics of the interferometric phases. Its significance lies in the fact that from it, one can derive the statistical properties of a wide range of quantities estimated from an interferometric stack, including the closure phases that we addressed in the paper. The other equations, numerical results, and the conclusions remain unaffected, because the error was of a purely typographical nature.
    Repository Name: EPIC Alfred Wegener Institut
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  • 18
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    Global warming has reached the top of the Greenland ice sheet (2023)
    Springer Nature
    In:  EPIC3Nature, Springer Nature, ISSN: 0028-0836
    Details
    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 19
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    Correction: Hoffmann-Abdi et al. Short-Term Meteorological and Environmental Signals Recorded in a Firn Core from a High-Accumulation Site on Plateau Laclavere, Antarctic Peninsula. Geosciences 2021, 11, 428 (2023)
    MDPI
    In:  EPIC3Geosciences, MDPI, 13(8), pp. 237-237, ISSN: 2076-3263
    Details
    Publication Date: 2024-04-29
    Description: The authors would like to make the following corrections to the published article [1]. In Section 1, fourth paragraph: In the sentence “Proxy Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.” the word “Proxy” should be deleted as it occurs twice. The sentence should have read: “Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.”. In Section 3.4, second paragraph: In the sentence “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (m = 7.76).” the “m =” should be deleted before “7.76” and “, 8” should be inserted after “GMWL”. The sentence should have read: “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL, 8) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (7.76).”. In Section 4.5, first paragraph: In the sentence “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r 〉 −0.6, p = 0; Table 5).” the “〉” in the parenthesis should be replaced by “=”. The sentence should have read: “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r = −0.6, p = 0; Table 5).”. In the original publication, there was a mistake in Table 1 [1]. The order of the values in the column “Accumulation Rate (kg m−2 a−1)” was reversed for the years 2012 to 2015. The authors state that the scientific results for the accumulation rates in Table 1, which are presented and discussed in Sections 3.2 and 4.2 of the original publication, are not affected by this mistake, as all values were used correctly there. The corrected Table 1 is as follows: Annual accumulation rates calculated for the OH-12 drill site for the period 2012–2015. In the original publication, there was a mistake in Figure 6 [1]. The intercept in the equation for the δ18O−δD relationship of firn core OH-12 should be +6.01 and not −6.01. The corrected equation is δD = 7.94 × δ18O + 6.01. A correction was also made to the second paragraph in Section 3.4, where in the sentence “However, intercepts differ significantly (OH-12: −6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).” the intercept of the δ18O−δD relationship of firn core OH-12 should accordingly be +6.01 and not −6.01. In addition, in the same sentence the word “the” should be inserted before the word “intercepts”. The sentence should have read: ”However, the intercepts differ significantly (OH-12: +6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).”. The updated Figure 6 is as follows: (a) δ18O–δD relationship of all considered precipitation samples collected at Bernardo O’Higgins station (OH) between 2008 and 2017 (n = 294; coloured dots) compared to the δ18O–δD relationship of firn core OH-12 (n = 414; white dots). The Global Meteoric Water Line (GMWL) is indicated in blue. The Local Meteoric Water Line (LMWL) established for the study site by Fernandoy et al. [31,32] is shown as a dashed red line and the LMWL derived in this study as a solid red line. For each δ18O–δD relationship, the equation, the coefficient of determination (R2) and the p-value (p) are given. (b) Time series of δ18O, δD and d excess of OH-12 constructed based on the weighted age scale. High-resolution data are shown as light-coloured lines and monthly means as bold lines. The authors apologize for any inconvenience these mistakes may have caused the readers. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.
    Repository Name: EPIC Alfred Wegener Institut
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  • 20
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    Pan-Arctic soil element bioavailability estimations (2023)
    Copernicus GmbH
    In:  EPIC3Earth System Science Data, Copernicus GmbH, 15(3), pp. 1059-1075, ISSN: 1866-3508
    Details
    Publication Date: 2024-04-29
    Description: Arctic soils store large amounts of organic carbon and other elements, such as amorphous silicon, silicon, calcium, iron, aluminum, and phosphorous. Global warming is projected to be most pronounced in the Arctic, leading to thawing permafrost which, in turn, changes the soil element availability. To project how biogeochemical cycling in Arctic ecosystems will be affected by climate change, there is a need for data on element availability. Here, we analyzed the amorphous silicon (ASi) content as a solid fraction of the soils as well as Mehlich III extractions for the bioavailability of silicon (Si), calcium (Ca), iron (Fe), phosphorus (P), and aluminum (Al) from 574 soil samples from the circumpolar Arctic region. We show large differences in the ASi fraction and in Si, Ca, Fe, Al, and P availability among different lithologies and Arctic regions. We summarize these data in pan-Arctic maps of the ASi fraction and available Si, Ca, Fe, P, and Al concentrations, focusing on the top 100cm of Arctic soil. Furthermore, we provide element availability values for the organic and mineral layers of the seasonally thawing active layer as well as for the uppermost permafrost layer. Our spatially explicit data on differences in the availability of elements between the different lithological classes and regions now and in the future will improve Arctic Earth system models for estimating current and future carbon and nutrient feedbacks under climate change (10.17617/3.8KGQUN, Schaller and Goeckede, 2022).
    Repository Name: EPIC Alfred Wegener Institut
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  • 21
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    Three-dimensional topology dataset of folded radar stratigraphy in northern Greenland (2023)
    Springer Nature
    In:  EPIC3Scientific Data, Springer Nature, 10(1), pp. 525-525, ISSN: 2052-4463
    Details
    Publication Date: 2024-04-29
    Description: We present a dataset of reconstructed three-dimensional (3D) englacial stratigraphic horizons in northern Greenland. The data cover four different regions representing key ice-dynamic settings in Greenland: (i) the onset of Petermann Glacier, (ii) a region upstream of the 79° North Glacier (Nioghalvfjerdsbræ), near the northern Greenland ice divide, (iii) the onset of the Northeast Greenland Ice Stream (NEGIS) and (iv) a 700 km wide region extending across the central ice divide over the entire northern part of central Greenland. In this paper, we promote the advantages of a 3D perspective of deformed englacial stratigraphy and explain how 3D horizons provide an improved basis for interpreting and reconstructing the ice-dynamic history. The 3D horizons are provided in various formats to allow a wide range of applications and reproducibility of results.
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  • 22
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    News from the EastGRIP ice core - on microstructure, impurities and the bridging of different scales (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: A better understanding of ice flow and deformation is needed to improve the projections of future sea level rise. Especially ice streams, the main contributors to solid ice discharge, still require more observational data to be represented sufficiently in computer models. The East Greenland Ice-core Project (EastGRIP) thus successfully drilled the first continuous deep ice core from an ice stream, the Northeast Greenland Ice Stream (NEGIS) while serving as a hub for geophysical measurements. A major unknown is the ice microstructure, i.e. the size and orientation of ice crystals (CPO) and its interplay with chemical impurities. Impurities are a climate proxy but are also assumed to impact microstructural processes, such as deformation and grain growth, and it is thus crucial to investigate where impurities are located in the microstructure. By combining microstructural (fabric analyser, microstructure-mapping, large area scanning macroscope) and impurity (Raman spectroscopy, inductively coupled plasma mass spectrometry 2D imaging) methods, we here present a systematic overview of the evolution of the microstructure and of the location of impurities throughout the EastGRIP ice core. Solid impurities, such as dust, are preferably located in the grain interior, while soluble impurities are mainly in the grain boundaries. This shows that microstructure should be considered when using impurities as a climate proxy due to the large spatial variability on the (sub-) millimetre scale. The analysed microstructure in the EastGRIP ice core further assists in reconstructing the original orientation of the ice core via visual stratigraphy, delivering the ground-truthing for an improved method of interfering horizontal fabric with co-polarised phase-sensitive radar and gaining new insights into the spatial variability of anisotropy and ice viscosity within NEGIS. Combining microstructural data with numerical modelling enables new insights into the processes underlying CPO formation and the bridging of different spatial scales to derive a more holistic picture of NEGIS and the governing processes.
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  • 23
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    Stabilization of mineral-associated organic carbon in Pleistocene permafrost (2023)
    Springer Science and Business Media LLC
    In:  EPIC3Nature Communications, Springer Science and Business Media LLC, 14(1), 8 p., ISSN: 2041-1723
    Details
    Publication Date: 2024-04-29
    Description: Ice-rich Pleistocene-age permafrost is particularly vulnerable to rapid thaw, which may quickly expose a large pool of sedimentary organic matter (OM) to microbial degradation and lead to emissions of climate-sensitive greenhouse gases. Protective physico-chemical mechanisms may, however, restrict microbial accessibility and reduce OM decomposition; mechanisms that may be influenced by changing environmental conditions during sediment deposition. Here we study different OM fractions in Siberian permafrost deposited during colder and warmer periods of the past 55,000 years. Among known stabilization mechanisms, the occlusion of OM in aggregates is of minor importance, while 33-74% of the organic carbon is associated with small, 〈6.3 µm mineral particles. Preservation of carbon in mineral-associated OM is enhanced by reactive iron minerals particularly during cold and dry climate, reflected by low microbial CO2 production in incubation experiments. Warmer and wetter conditions reduce OM stabilization, shown by more decomposed mineral-associated OM and up to 30% higher CO2 production. This shows that considering the stability and bioavailability of Pleistocene-age permafrost carbon is important for predicting future climate-carbon feedback.
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  • 24
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    Exploring shoulder season greenhouse gas production along a permafrost thaw transect in sub-arctic Finnish Palsas (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: The future of terrestrial carbon found in permafrost is not yet well understood, but this soil carbon may be a potential significant contributor to positive-feedback loop of climatic warming. In the (sub)arctic, the annual freeze-thaw cycles and thick peat accumulation harbor ideal conditions for palsa formation. Although, a recent study at our site in Arctic Lapland found that the area of the carbon-rich palsa mounds have already decreased by -77 % to -90 % since 1960. Here, we investigate potential greenhouse gas (CO2, CH4, N2O) production from a palsa sampled along a transect with 60+ years of documented thaw. During the annual cycle of freeze-thaw, one of the largest unknowns in the life cycle of a palsa mound is the biogeochemical cycles during the shoulder season. This transition time between growing, and non-growing seasons that have previously been assumed to be times of relative dormancy for GHG flux in high-latitude wetlands. However, recent studies find that there is in fact a significant amount of GHG flux during this time. We aim to isolate shoulder season variables (increased N from plant senescence, temperature change) and explore how they each affect the potential CO2 and CH4 production using ex-situ incubations, coupled with microbial community cell counts sampled in tandem. Here, we test whether N addendums increase the GHG, as n-poor habitat has been shown to respond with increased microbial activity to the release of this metabolic bottleneck. In addition to the N-treatments, the samples will also be separated into three incubation temperature groups (4 , 15, 20C) to be able to link increasing temperatures with the N response. Overall, we aim to fill knowledge gaps on these habitats response to changing climatic conditions, and use our findings to better earth system models permafrost carbon predictions.
    Repository Name: EPIC Alfred Wegener Institut
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  • 25
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    Was ist so spannend an alter Luft? (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Description: Eiskerne sind ein einmaliger Zugang zur Atmosphäre vergangener Zeiten. Aber was ist daran so spannend? Eines der ungelösten Probleme bei der Erforschung des Klimas der Vergangenheit ist wie es vor ca. 1.5 Millionen Jahren (für Geologen: im mittleren Pleistozän) dazu kam, dass sich der wiederkehrende Wechsel der Kalt- und Warmzeiten von 40 Tausend auf 100 Tausend Jahre vergrößerte. Das europäische Projekt Beyond EPICA – Oldest Ice will dem auf den Grund gehen. Dazu soll in der Antarktis der ersten Eiskern erbohrt werden, mit dem uralte Lufteinschlüsse an die Oberfläche gebracht werden, die diesen Zeitraum kontinuierlich abdecken. In Episode 149 gibt Olaf Eisen, Professor für Glaziologie am Alfred-Wegener-Institut und der Universität Bremen, in seinem Vortrag einen Einblick in die Motivation für das Projekt und die bisherige Reise zu einem neuen Eiskern.
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  • 26
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    Vegetation history of central Chukotka deduced from permafrost paleoenvironmental records of the El'gygytgyn Impact Crater (2012)
    Copernicus Publications
    In:  EPIC3Climate of the Past, Copernicus Publications, 8(4), pp. 1287-1300, ISSN: 1814-9324
    Details
    Publication Date: 2024-04-29
    Description: Frozen sediments from three cores bored in the permafrost surrounding the El’gygytgyn Impact Crater Lake have been studied for pollen, non-pollen palynomorphs, plant macrofossils and rhizopods. The palynological study of these cores contributes to a higher resolution of time intervals presented in a poor temporal resolution in the lacustrine sediments; namely the Allerød and succeeding periods. Moreover, the permafrost records better reflect local environmental changes, allowing a more reliable reconstruction of the local paleoenvironments. The new data confirm that shrub tundra with dwarf birch, shrub alder and willow dominated the lake surroundings during the Allerød warming. Younger Dryas pollen assemblages reflect abrupt changes to grass-sedge-herb dominated environments reflecting significantly drier and cooler climate. Low shrub tundra with dwarf birch and willow dominate the lake vicinity at the onset of the Holocene. The find of larch seeds indicate its local presence around 11 000 cal yr BP and, thus a northward shift of treeline by about 100 km during the early Holocene thermal optimum. Forest tundra with larch and shrub alder stands grew in the area during the early Holocene. After ca. 3500 cal yr BP similar-to-modern plant communities became common in the lake vicinity.
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  • 27
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    Antarctic Bedmap data: Findable, Accessible, Interoperable, and Reusable (FAIR) sharing of 60 years of ice bed, surface, and thickness data (2023)
    Copernicus Publications
    In:  EPIC3Earth System Science Data, Copernicus Publications, 15(7), pp. 2695-2710, ISSN: 1866-3508
    Details
    Publication Date: 2024-04-29
    Description: One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and the ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action Group aims not only to produce new gridded maps of ice thickness and bed topography for the international scientific community, but also to standardize and make available all the geophysical survey data points used in producing the Bedmap gridded products. Here, we document the survey data used in the latest iteration, Bedmap3, incorporating and adding to all of the datasets previously used for Bedmap1 and Bedmap2, including ice bed, surface and thickness point data from all Antarctic geophysical campaigns since the 1950s. More specifically, we describe the processes used to standardize and make these and future surveys and gridded datasets accessible under the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. With the goals of making the gridding process reproducible and allowing scientists to re-use the data freely for their own analysis, we introduce the new SCAR Bedmap Data Portal (https://bedmap.scar.org, last access: 1 March 2023) created to provide unprecedented open access to these important datasets through a web-map interface. We believe that this data release will be a valuable asset to Antarctic research and will greatly extend the life cycle of the data held within it. Data are available from the UK Polar Data Centre: https://data.bas.ac.uk (last access: 5 May 2023). See the Data availability section for the complete list of datasets.
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  • 28
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    Effect of post-thaw hydrological changes during the degradation process of a palsa (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: With climate change, discontinuous permafrost is thawing rapidly and is predicted to reach a “tipping point” in the next decade. Permafrost affected peatlands store about 185±66 Pg C. Due to permafrost thaw, the landscape topographies and hydrologic conditions could change quickly and thus, release carbon (C) stored in soils. However, there is a current lack of understanding regarding the C lability after post- thaw and how the microbial community and labile C in the water will affect methane (CH4) and carbon dioxide (CO2) fluxes. Here, we quantified and qualified the effect of hydrologic changes on CH4 and CO2 emissions and production during the thawing process of a palsa (peaty permafrost mounts, mainly in discontinuous permafrost areas). We did a chronosequence study by measuring CH4 and CO2 emissions along a thawing transect from an intact palsa to a thawed wetland site during fall. Additionally, we mimicked a palsa degradation by incubating 1 m soil cores from the palsa and the wetland sites. We inoculated the incubation with water from the thawed site to study the effect of hydrological changes after permafrost thaw. The CO2 and CH4 emissions were continuously measured for 60 days. Additionally, dissolved gas, as well as nutrients were sampling over the entirety of the incubation time. The preliminary results from the field measurements showed that the intact palsa and the intermediate site behaved as a net C sink whereas, the thawed wetland site had the highest CH4 emissions (20 – 40 ppm). Furthermore, we showed that this mesocosm-scale incubation setup is an efficient and robust way to study C cycle dynamics and more accurately upscale laboratory results to the field. With permafrost thaw and former areas turning into wetlands more greenhouse gases will be emitted. Therefore, bridging scale is necessary to better estimate the future C emissions.
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  • 29
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    Alkalinity biases in CMIP6 Earth system models and implications for simulated CO2 drawdown via artificial alkalinity enhancement (2023)
    Copernicus GmbH
    In:  EPIC3Biogeosciences, Copernicus GmbH, 20(18), pp. 3717-3735, ISSN: 1726-4170
    Details
    Publication Date: 2024-04-29
    Description: The partitioning of CO2 between atmosphere and ocean depends to a large degree not only on the amount of dissolved inorganic carbon (DIC) but also on alkalinity in the surface ocean. That is also why ocean alkalinity enhancement (OAE) is discussed as one potential approach in the context of negative emission technologies. Although alkalinity is thus an important variable of the marine carbonate system, little knowledge exists on how its representation in models compares with measurements. We evaluated the large-scale alkalinity distribution in 14 CMIP6 Earth system models (ESMs) against the observational data set GLODAPv2 and show that most models, as well as the multi-model mean, underestimate alkalinity at the surface and in the upper ocean and overestimate it in the deeper ocean. The decomposition of the global mean alkalinity biases into contributions from (i) physical processes (preformed alkalinity), which include the physical redistribution of biased alkalinity originating from the soft tissue and carbonates pumps; (ii) remineralization; and (iii) carbonate formation and dissolution showed that the bias stemming from the physical redistribution of alkalinity is dominant. However, below the upper few hundred meters the bias from carbonate dissolution can gain similar importance to physical biases, while the contribution from remineralization processes is negligible. This highlights the critical need for better understanding and quantification of processes driving calcium carbonate dissolution in microenvironments above the saturation horizons and implementation of these processes into biogeochemical models. For the application of the models to assess the potential of OAE to increase ocean carbon uptake, a back-of-the-envelope calculation was conducted with each model's global mean surface alkalinity, DIC, and partial pressure of CO2 in seawater (pCO2) as input parameters. We evaluate the following two metrics: (1) the initial pCO2 reduction at the surface ocean after alkalinity addition and (2) the uptake efficiency (ηCO2) after air–sea equilibration is reached. The relative biases of alkalinity versus DIC at the surface affect the Revelle factor and therefore the initial pCO2 reduction after alkalinity addition. The global mean surface alkalinity bias relative to GLODAPv2 in the different models ranges from −85 mmol m−3 (−3.6 %) to +50 mmol m−3 (+2.1 %) (mean: −25 mmol m−3 or −1.1 %). For DIC the relative bias ranges from −55 mmol m−3 (−2.6 %) to 53 mmol m−3 (+2.5 %) (mean: −13 mmol m−3 or −0.6 %). All but two of the CMIP6 models evaluated here overestimate the Revelle factor at the surface by up to 3.4 % and thus overestimate the initial pCO2 reduction after alkalinity addition by up to 13 %. The uptake efficiency, ηCO2, then takes into account that a higher Revelle factor and a higher initial pCO2 reduction after alkalinity addition and equilibration mostly compensate for each other, meaning that resulting DIC differences in the models are small (−0.1 % to 1.1 %). The overestimation of the initial pCO2 reduction has to be taken into account when reporting on efficiencies of ocean alkalinity enhancement experiments using CMIP6 models, especially as long as the CO2 equilibrium is not reached.
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  • 30
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    Stratigraphic noise and its potential drivers across the plateau of Dronning Maud Land, East Antarctica (2023)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 17(10), pp. 4207-4221, ISSN: 1994-0416
    Details
    Publication Date: 2024-04-29
    Description: Stable water isotopologues of snow, firn and ice cores provide valuable information on past climate variations. Yet single profiles are generally not suitable for robust climate reconstructions. Stratigraphic noise, introduced by the irregular deposition, wind-driven erosion and redistribution of snow, impacts the utility of high-resolution isotope records, especially in low-Accumulation areas. However, it is currently unknown how stratigraphic noise differs across the East Antarctic Plateau and how it is affected by local environmental conditions. Here, we assess the amount and structure of stratigraphic noise at seven sites along a 120 km transect on the plateau of Dronning Maud Land, East Antarctica. Replicated oxygen isotope records of 1 m length were used to estimate signal-To-noise ratios as a measure of stratigraphic noise at sites characterised by different accumulation rates (43-64 mm w.e. a-1), snow surface roughnesses and slope inclinations. While we found a high level of stratigraphic noise at all sites, there was also considerable variation between sites. At sastrugi-dominated sites, greater stratigraphic noise coincided with stronger surface roughnesses, steeper slopes and lower accumulation rates, probably related to increased wind speeds. These results provide a first step to modelling stratigraphic noise and might guide site selection and sampling strategies for future expeditions to improve high-resolution climate reconstructions from low-Accumulation regions.
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  • 31
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    Guanidinium Toxins: Evolution, Mode of Action and Chemical Ecology (2021)
    Elsevier
    In:  EPIC3Elsevier, ISBN: 9780128220146
    Details
    Publication Date: 2024-04-29
    Description: Marine Neurotoxins, Volume Five provides comprehensive information on marine toxins present in the human food chain and the affecting targets relevant for the functioning of the brain and our nervous system, covering all the information ...
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  • 32
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    Guanidinium Toxins: Evolution, Mode of Action and Chemical Ecology (2021)
    Elsevier
    In:  EPIC3Elsevier, ISBN: 9780128220146
    Details
    Publication Date: 2024-04-29
    Description: Marine Neurotoxins, Volume Five provides comprehensive information on marine toxins present in the human food chain and the affecting targets relevant for the functioning of the brain and our nervous system, covering all the information ...
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  • 33
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    Large Herbivores and Their Interaction with Arctic Soil Carbon Storage (2022)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: Permafrost degradation and organic matter decomposition in the terrestrial Arctic are strongly depending on soil temperatures. A factor that affects these temperatures is grazing and snow trampling by large herbivorous animals, as well as animal-induced changes in vegetation cover. We analysed samples taken from adjacent areas with different grazing intensities, both in a permafrost environment (Siberia) and seasonally frozen ground (norther Finland) for TOC, C/N ratio, d13C, bulk density and radiocarbon age. While in permafrost there was a strong increase in soil carbon storage with high grazing intensity, this effect is not visible in seasonally frozen ground. However, in both areas we observed massive changes in vegetation composition and structure, following the grazing gradient. We conclude that seasonally frozen ground allows for more intensive carbon relocation and mixing, which outweighs the effects animals have in the permafrost region but state that on permafrost, animals might efficiently be utilized to stabilise permafrost temperatures and reduce organic material decomposition.
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  • 34
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    How ice anisotropy contributes to fold and ice stream in large-scale ice-sheet models (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: Satellite and airborne sensors have provided detailed data on ice surface flow velocities, englacial structures of ice sheets and bedrock elevations. These data give insight into the flow behaviour of ice sheets and glaciers. One significant phenomenon observed is large-scale folds (over 100 m in amplitude) in the englacial stratigraphy in the Greenland ice sheet. A large population of folds is located at ice streams, where the flow is distinctly faster than in the surroundings, such as the North-East Greenland Ice Stream (NEGIS). While there is no consensus regarding the formation of large-scale folds, unraveling the underlying mechanisms presents significant potential for enhancing our understanding of the formation and dynamics of ice streams. Ice in ice sheets is a ductile material, i.e., it can flow as a thick viscous fluid with a power-law rheology. Furthermore, ice is significantly anisotropic in its flow properties due to its crystallographic preferred orientation (CPO). Here, we use the Full-Stokes code Underworld2 (Mansour et al.,2022) for 3D modelling of the power-law and transversely isotropic ice flow, also in comparison with the isotropic ice models. Our simulated folds with anisotropic ice show complex patterns on a bumpy bedrock, and are classified into three types: large-scale folds (fold amplitudes 〉100 m), small-scale folds (fold amplitudes 〈〈100 m, wavelength 〈〈km) and recumbent basal-shear folds. Our results indicate that bedrock topography contributes to perturbations in ice layers, and that ice anisotropy due to the CPO amplifies these into large-scale folds in convergent flow by horizontal shortening. As for our ice stream model, we simulate convergent flow as initial condition, which subsequently initiates the development of shear margins due to the rotation of the ice crystal basal planes. As soon as the shear margins develop, the ice stream starts to propagate upstream in a short time and narrows in the upstream part. Our modeling shows that the anisotropic rheology of ice and CPO change play a significant role for large-scale folding and for the initiation of ice streams with distinct shear margins. Hence, we promote the implementation of ice anisotropy in large-scale ice-sheet evolution models as it holds the potential to introduce novel perspectives to the glaciological community on the dynamics of ice flow.
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  • 35
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    Carbon isotopes in the marine biogeochemistry model FESOM2.1-REcoM3 (2024)
    Copernicus GmbH
    In:  EPIC3Geoscientific Model Development, Copernicus GmbH, 17(4), pp. 1709-1727, ISSN: 1991-959X
    Details
    Publication Date: 2024-04-29
    Description: 〈jats:p〉Abstract. In this paper we describe the implementation of the carbon isotopes 13C and 14C (radiocarbon) into the marine biogeochemistry model REcoM3. The implementation is tested in long-term equilibrium simulations where REcoM3 is coupled with the ocean general circulation model FESOM2.1, applying a low-resolution configuration and idealized climate forcing. Focusing on the carbon-isotopic composition of dissolved inorganic carbon (δ13CDIC and Δ14CDIC), our model results are largely consistent with reconstructions for the pre-anthropogenic period. Our simulations also exhibit discrepancies, e.g. in upwelling regions and the interior of the North Pacific. Some of these differences are due to the limitations of our ocean circulation model setup, which results in a rather shallow meridional overturning circulation. We additionally study the accuracy of two simplified modelling approaches for dissolved inorganic 14C, which are faster (15 % and about a factor of five, respectively) than the complete consideration of the marine radiocarbon cycle. The accuracy of both simplified approaches is better than 5 %, which should be sufficient for most studies of Δ14CDIC. 〈/jats:p〉
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    A structural geologist's view on the Northeast Greenland Ice Stream (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: The Northeast Greenland Ice Stream (NEGIS) is a fascinating, over 500 km long structure in the Greenland Ice Sheet. The ice stream shows many features, such as folds and shear zones, that are also common in other ductile rocks. Geological methods and expertise may contribute to a better understanding of NEGIS and similar deformation structures in ice sheets. It is standard practice in oil and gas exploration to create 3D-structural models from parallel seismic lines. This approach, applied to radar profiles, is relatively new in glaciology (Bons et al., Nat. Comm. 2016, DOI: 10.1038/ncomms11427) but provides far more insight into the structural architecture and evolution of ice sheets than single radar sections. A 3D-structural model of upstream NEGIS reveals how pre-existing folds are offset within the ice stream. With that, classical strain analysis methods can be applied to quantify the deformation of these folds in the shear margins. This reveals that the total offset at the level of the EGRIP drilling project is in the order of up to 75 km and that the finite shear strain in the shear margins is around 18. With present-day shear-strain rates in the shear margins, such a finite offset and shear strain are achieved in ≤2000 yrs. This strain analysis also proves that ice does not flow through shear margins, but that the shear margins instead advect with the ice. This means that 'flow lines' (which should better be called 'streamlines') are not the same as 'path lines', as is now often assumed. The two are only the same in a time-invariant velocity field, which does not apply to NEGIS. Shear zones in other ductile rocks show that rocks never flow through shear zones, but shear zones can shift or 'jump' to new locations, as is actually observed in NEGIS. Geological principles to analyse and date the formation and activity of salt diapirs and syn-sedimentary faults can also be applied to folds observed in and around NEGIS. This reveals that fold amplification inside the shear margins ceased about 2000 yrs ago, which can be explained by the formation of the shear margins and concomitant reorientation of the CPO. A combination of several structural geological methods thus enables constraining the age of NEGIS as we now know it to about 2000 yrs, which is much less than previously assumed. The surprisingly late appearance of NEGIS, as well as the demise of ice streams in the Holocene (based on 3D-analyses of folded stratigraphy; Franke et al., Nature Geosci. 2022, Doi: 10.1038/s41561-022-01082-2) indicates that ice sheets are very dynamic, mostly due to the highly non-linear (n=4) and anisotropic rheology of ice.
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  • 37
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    Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia (2016)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 9(4), pp. 1449-1462, ISSN: 1994-0416
    Details
    Publication Date: 2024-04-29
    Description: Coastal erosion and flooding transform terrestrial landscapes into marine environments. In the Arctic, these processes inundate terrestrial permafrost with seawater and create submarine permafrost. Permafrost begins to warm under marine conditions, which can destabilize the sea floor and may release greenhouse gases. We report on the transition of terrestrial to submarine permafrost at a site where the timing of inundation can be inferred from the rate of coastline retreat. On Muostakh Island in the central Laptev Sea, East Siberia, changes in annual coastline position have been measured for decades and vary highly spatially. We hypothesize that these rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost (IBP) based on the consequent duration of inundation with increasing distance from the shoreline. We compared rapidly eroding and stable coastal sections of Muostakh Island and find permafrost-table inclinations, determined using direct current resistivity, of 1 and 5 %, respectively. Determinations of submarine IBP depth from a drilling transect in the early 1980s were compared to resistivity profiles from 2011. Based on borehole observations, the thickness of unfrozen sediment overlying the IBP increased from 0 to 14m below sea level with increasing distance from the shoreline. The geoelectrical profiles showed thickening of the unfrozen sediment overlying ice-bonded permafrost over the 28 years since drilling took place. We use geoelectrical estimates of IBP depth to estimate permafrost degradation rates since inundation. Degradation rates decreased from over 0.4ma-1 following inundation to around 0.1ma-1 at the latest after 60 to 110 years and remained constant at this level as the duration of inundation increased to 250 years. We suggest that long-term rates are lower than these values, as the depth to the IBP increases and thermal and porewater solute concentration gradients over depth decrease. For the study region, recent increases in coastal erosion rate and changes in benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP.
    Repository Name: EPIC Alfred Wegener Institut
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    Radar internal reflection horizons from multisystem data reflect ice dynamic and surface accumulation history along the Princess Ragnhild Coast, Dronning Maud Land, East Antarctica (2023)
    Cambridge University Press (CUP)
    In:  EPIC3Journal of Glaciology, Cambridge University Press (CUP), pp. 1-19, ISSN: 0022-1430
    Details
    Publication Date: 2024-04-29
    Description: Ice shelves, which regulate ice flow from the Antarctic ice sheet towards the ocean, are shaped by spatiotemporal patterns of surface accumulation, surface/basal melt and ice dynamics. Therefore, an ice dynamic and accumulation history are imprinted in the internal ice stratigraphy, which can be imaged by radar in the form of internal reflection horizons (IRHs). Here, IRHs were derived from radar data combined across radar platforms (airborne and ground-based) in coastal eastern Dronning Maud Land (East Antarctica), comprising three ice rises and adjacent two ice shelves. To facilitate interpretation of dominant spatiotemporal patterns of processes shaping the local IRH geometry, traced IRHs are classified into three different types (laterally continuous, discontinuous or absent/IRH-free). Near-surface laterally continuous IRHs reveal local accumulation patterns, reflecting the mean easterly wind direction, and correlate with surface slopes. Areas of current and past increased ice flow and internal deformation are marked by discontinuous or IRH-free zones, and can inform about paleo ice-stream dynamics. The established IRH datasets extend continent-wide mapping efforts of IRHs to an important and climatically sensitive ice marginal region of Antarctica and are ready for integration into ice-flow models to improve predictions of Antarctic ice drainage.
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  • 39
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    Spatial and temporal changes in surface mass balance derived from airborne radio sounding for the plateau area in Dronning Maud Land (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: Contrary to the rest of the Antarctic ice sheet, East Antarctica currently gains mass due to an increase in snow accumulation over the last decades. How or if this increase is linked to anthropogenic warming is not yet clear and requires better understanding of the surface mass balance history over the last centuries, and also the dependency of snow accumulation with the local surface slopes across different spatial scales. Here, we present a novel airborne dataset using the multichannel ultra-wideband radar system from the Alfred Wegener Institute in Germany with a decadal vertical resolution for the plateau area in Dronning Maud Land. We assess the spatial and temporal variability of surface mass balance and snow accumulation for the past centuries for an area of ~200,000 km2. With this contribution, we aim to (1) show the potential to use ultra-wideband radar systems to reconstruct the recent surface mass balance and accumulation rates in low-accumulation regions, (2) present information on large spatial scales, and (3) discuss potential overlap of interests and/or data in this and/or other areas on the plateau of East Antarctica.
    Repository Name: EPIC Alfred Wegener Institut
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  • 40
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    Deciphering stable water isotope records of firn cores from a strongly maritime, high-accumulation site on the Antarctic Peninsula (2023)
    Cambridge University Press (CUP)
    In:  EPIC3Journal of Glaciology, Cambridge University Press (CUP), pp. 1-19, ISSN: 0022-1430
    Details
    Publication Date: 2024-04-29
    Description: Stable water isotope records of six firn cores retrieved from two adjacent plateaus on the northern Antarctic Peninsula between 2014 and 2016 are presented and investigated for their connections with firn-core glacio-chemical data, meteorological records and modelling results. Average annual accumulation rates of 2500 kg m-2 a-1 largely reduce the modification of isotopic signals in the snowpack by post-depositional processes, allowing excellent signal preservation in space and time. Comparison of firn-core and ECHAM6-wiso modelled δ18O and d-excess records reveals a large agreement on annual and sub-annual scales, suggesting firn-core stable water isotopes to be representative of specific synoptic situations. The six firn cores exhibit highly similar isotopic patterns in the overlapping period (2013), which seem to be related to temporal changes in moisture sources rather than local near-surface air temperatures. Backward trajectories calculated with the HYSPLIT model suggest that prominent δ18O minima in 2013 associated with elevated sea salt concentrations are related to long-range moisture transport dominated by westerly winds during positive SAM phases. In contrast, a broad δ18O maximum in the same year accompanied by increased concentrations of black carbon and mineral dust corresponds to the advection of more locally derived moisture with northerly flow components (South America) when the SAM is negative.
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  • 41
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    Simulated radiocarbon cycle revisited by considering the bipolar seesaw and benthic 14C data (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 42
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    Simulated radiocarbon cycle revisited by considering the bipolar seesaw and benthic 14C data (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 43
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    Dependence of the isotopic composition of different precipitation types on air temperature in Central Antarctica (2021)
    FSBI Arctic and Antarctic Research Institute (FSBI AARI)
    In:  EPIC3Arctic and Antarctic Research, FSBI Arctic and Antarctic Research Institute (FSBI AARI), 67(4), pp. 368-381, ISSN: 0555-2648
    Details
    Publication Date: 2024-04-29
    Description: 〈jats:p〉Water isotopes are key proxies to reconstruct past climatic conditions on our planet based on Antarctic ice core data. The accuracy of climate reconstructions depends on understanding the whole range of the processes involved in the formation of precipitation isotopic composition. The isotopic composition of precipitation in Central Antarctica has been studied in a number of works, but the difference between the isotopic composition of different types of precipitation has not yet been fully described.There are three main type of precipitation in Central Antarctica: snow, ice needles and hoar. The aim of this work is to establish the dependence of isotopic composition of different precipitation types on temperature. Precipitation samples were collected at Vostok station in Central Antarctica from 1998 to 2020 and further analyzed for δ18O and δD. For each precipitation event we have meteorological data, averaged over the time of precipitation fallout. Mean values of δD for each precipitation type were defined as follows: –444±6.5 ‰ for diamond dust, –480± 6 ‰ for hoar and –95±11 ‰ for snow. The seasonal variability of the temperature dependence of the isotopic composition was studied using the example of ice needles. According to our data, the dependence is insignificant in winter, but this needs to be confirmed by an extended dataset. The largest slope of the isotope-temperature dependence regression line is observed for the summer period and is equal to 5.34±3.11 ‰·°С–1, the autumn season has a slope of 2.1±1.3 ‰·°С–1, while for the spring period we do not have enough data for analysis. There is an insignificant difference in the slopes of the isotope-temperature dependence for different types of precipitation: 2.93±0.51 ‰·°С–1 for ice needles, 2.32±1.34 ‰·°С–1 for snow and 2.52±0.35 ‰·°С–1 for hoar. We studied the effect of blizzards on the isotopic composition of samples and concluded that one should avoid using data collected during a blizzard to study the differences in the formation of the isotopic signal for different types of precipitation.This work brings us closer to understanding how isotopic composition is formed in each type of precipitation and what information it provides. This will contribute to a more accurate interpretation of the isotope signal from ice cores.〈/jats:p〉
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  • 44
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    A Revisionist View of the Mid-Pleistocene Transition (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 45
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    Simulated radiocarbon cycle revisited by considering the bipolar seesaw and benthic 14C data (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 46
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    Sediment-laden basal ice units near the onset of a fast-flowing glacier in East Antarctica (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Description: Understanding the material properties and physical conditions of basal ice is crucial for a comprehensive understanding of Antarctic ice-sheet dynamics. Yet, direct data are sparse and difficult to acquire, necessitating geophysical data for analysis. We employed high-resolution ultra-wideband radar to map high-backscatter zones near the glacier bed within East Antarctica's Jutulstraumen drainage basin. In addition, we used radar forward modelling to constrain their material composition. Our results reveal along-flow oriented sediment-laden basal ice units connected to the basal substrate, extending to several hundred meters thick. Three-dimensional thermomechanical modelling suggests these units initially form via basal freeze-on of subglacial water originating upstream. We suggest that basal freeze-on and the entrainment and transport of subglacial material play a significant role in an accurate representation of the material, physical, and rheological properties of the Antarctic ice sheet's basal ice, ultimately enhancing the accuracy and reliability of ice-sheet modelling.
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  • 47
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    Ice sheet related glacial/interglacial cyclicity of granitic tetrafluoromethane (CF4) emissions before and after the Mid Brunhes (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 48
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    Isotopic signatures of snow, sea ice, and surface seawater in the central Arctic Ocean during the MOSAiC expedition (2024)
    University of California Press
    In:  EPIC3Elementa: Science of the Anthropocene, University of California Press, 12(1), ISSN: 2785-4558
    Details
    Publication Date: 2024-04-29
    Description: The Arctic Ocean is an exceptional environment where hydrosphere, cryosphere, and atmosphere are closely interconnected. Changes in sea-ice extent and thickness affect ocean currents, as well as moisture and heat exchange with the atmosphere. Energy and water fluxes impact the formation and melting of sea ice and snow cover. Here, we present a comprehensive statistical analysis of the stable water isotopes of various hydrological components in the central Arctic obtained during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2019–2020, including the understudied Arctic winter. Our dataset comprises 〉2200 water, snow, and ice samples. Snow had the most depleted and variable isotopic composition, with d18O (–16.3%) increasing consistently from surface (–22.5%) to bottom (–9.7%) of the snowpack, suggesting that snow metamorphism and wind-induced transport may overprint the original precipitation isotope values. In the Arctic Ocean, isotopes also help to distinguish between different sea-ice types, and whether there is a meteoric contribution. The isotopic composition and salinity of surface seawater indicated relative contributions from different freshwater sources: lower d18O (approximately –3.0%) and salinities were observed near the eastern Siberian shelves and towards the center of the Transpolar Drift due to river discharge. Higher d18O (approximately –1.5%) and salinities were associated with an Atlantic source when the RV Polarstern crossed the Gakkel Ridge into the Nansen Basin. These changes were driven mainly by the shifts within the Transpolar Drift that carried the Polarstern across the Arctic Ocean. Our isotopic analysis highlights the importance of investigating isotope fractionation effects, for example, during sea-ice formation and melting. A systematic full-year sampling for water isotopes from different components strengthens our understanding of the Arctic water cycle and provides crucial insights into the interaction between atmosphere, sea ice, and ocean and their spatio-temporal variations during MOSAiC.
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  • 49
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    Effective Spatial Degrees of Freedom of Natural Temperature Variability as a Function of Frequency (2024)
    American Meteorological Society
    In:  EPIC3Journal of Climate, American Meteorological Society, 37(8), pp. 2505-2518, ISSN: 0894-8755
    Details
    Publication Date: 2024-04-29
    Description: A fundamental statistic of climate variability is its spatiotemporal correlation function. Its complex structure can be concisely summarized by a frequency-dependent measure of the effective spatial degrees of freedom (ESDOF). Here we present, for the first time, frequency-dependent ESDOF estimates of global natural surface temperature variability from purely instrumental measurements, using the HadCRUT4 dataset (1850-2014). The approach is based on a newly developed method for estimating the frequency-dependent spatial correlation function from gappy data fields. Results reveal a multicomponent structure of the spatial correlation function, including a large-amplitude short-distance component (with weak time scale dependence) and a small-amplitude long-distance component (with increasing relative amplitude toward the longer time scales). Two frequency-dependent ESDOF measures are applied, each responding mainly to either of the two components. Both measures exhibit a significant ESDOF reduction from monthly to multidecadal time scales, implying an increase of the effective spatial scale of natural surface temperature fluctuations. Moreover, it is found that a good approximation to the global number of equally spaced samples needed to estimate the variance of global mean temperature is given, at any frequency, by the greater one of the two ESDOF measures, decreasing from ;130 at monthly to ;30 at multidecadal time scales. Finally, the multicomponent structure of the correlation function together with the detected ESDOF scaling properties indicate that the ESDOF reduction toward the longer time scales cannot be explained simply by diffusion acting on stochastically driven anomalies, as it might be suggested f rom simple stochastic-diffusive energy balance models.
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  • 50
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    Constraining glacial ocean carbon cycle – A multi-model study (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
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  • 51
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    Reviews and syntheses: A framework to observe, understand and project ecosystem response to environmental change in the East Antarctic Southern Ocean (2022)
    Copernicus GmbH
    In:  EPIC3Biogeosciences, Copernicus GmbH, 19(22), pp. 5313-5342, ISSN: 1810-6277
    Details
    Publication Date: 2024-04-29
    Description: 〈jats:p〉Abstract. Systematic long-term studies on ecosystem dynamics are largely lacking from the East Antarctic Southern Ocean, although it is well recognized that they are indispensable to identify the ecological impacts and risks of environmental change. Here, we present a framework for establishing a long-term cross-disciplinary study on decadal timescales. We argue that the eastern Weddell Sea and the adjacent sea to the east, off Dronning Maud Land, is a particularly well suited area for such a study, since it is based on findings from previous expeditions to this region. Moreover, since climate and environmental change have so far been comparatively muted in this area, as in the eastern Antarctic in general, a systematic long-term study of its environmental and ecological state can provide a baseline of the current situation, which will be important for an assessment of future changes from their very onset, with consistent and comparable time series data underpinning and testing models and their projections. By establishing an Integrated East Antarctic Marine Research (IEAMaR) observatory, long-term changes in ocean dynamics, geochemistry, biodiversity, and ecosystem functions and services will be systematically explored and mapped through regular autonomous and ship-based synoptic surveys. An associated long-term ecological research (LTER) programme, including experimental and modelling work, will allow for studying climate-driven ecosystem changes and interactions with impacts arising from other anthropogenic activities. This integrative approach will provide a level of long-term data availability and ecosystem understanding that are imperative to determine, understand, and project the consequences of climate change and support a sound science-informed management of future conservation efforts in the Southern Ocean. 〈/jats:p〉
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  • 52
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    Modern temperatures in central–north Greenland warmest in past millennium (2023)
    Springer Nature
    In:  EPIC3Nature, Springer Nature, 613(7944), pp. 503-507, ISSN: 0028-0836
    Details
    Publication Date: 2024-04-29
    Description: The Greenland Ice Sheet has a central role in the global climate system owing to its size, radiative effects and freshwater storage, and as a potential tipping point1. Weather stations show that the coastal regions are warming2, but the imprint of global warming in the central part of the ice sheet is unclear, owing to missing long-term observations. Current ice-core-based temperature reconstructions3–5 are ambiguous with respect to isolating global warming signatures from natural variability, because they are too noisy and do not include the most recent decades. By systematically redrilling ice cores, we created a high-quality reconstruction of central and north Greenland temperatures from ad 1000 until 2011. Here we show that the warming in the recent reconstructed decade exceeds the range of the pre-industrial temperature variability in the past millennium with virtual certainty (P < 0.001) and is on average 1.5 ± 0.4 degrees Celsius (1 standard error) warmer than the twentieth century. Our findings suggest that these exceptional temperatures arise from the superposition of natural variability with a long-term warming trend, apparent since ad 1800. The disproportionate warming is accompanied by enhanced Greenland meltwater run-off, implying that anthropogenic influence has also arrived in central and north Greenland, which might further accelerate the overall Greenland mass loss.
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  • 53
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    Simulated radiocarbon cycle revisited by considering the bipolar seesaw and benthic 14C data (2024)
    In:  EPIC3
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    Publication Date: 2024-04-29
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  • 54
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    Bridging gaps in permafrost-shrub understanding (2024)
    Public Library of Science (PLoS)
    In:  EPIC3PLOS Climate, Public Library of Science (PLoS), 3(3), pp. e0000360-e0000360, ISSN: 2767-3200
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    Publication Date: 2024-04-29
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  • 55
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    Spatial and temporal stable water isotope data from the upper snowpack at the EastGRIP camp site, NE Greenland, sampled in summer 2018 (2024)
    Copernicus Publications
    In:  EPIC3Earth System Science Data, Copernicus Publications, 16(4), pp. 1861-1874, ISSN: 1866-3508
    Details
    Publication Date: 2024-04-29
    Description: 〈jats:p〉Abstract. Stable water isotopes stored in snow, firn and ice are used to reconstruct climatic parameters. The imprint of these parameters at the snow surface and their preservation in the upper snowpack are determined by a number of processes influencing the recording of the environmental signal. Here, we present a dataset of approximately 3800 snow samples analysed for their stable water isotope composition, which were obtained during the summer season next to the deep drilling site of the East Greenland Ice Core Project in northeast Greenland (75.635411° N, 36.000250° W). Sampling was carried out every third day between 14 May and 3 August 2018 along a 39 m long transect. Three depth intervals in the top 10 cm were sampled at 30 positions with a higher resolution closer to the surface (0–1 and 1–4 cm depth vs. 4–10 cm). The sample analysis was carried out at two renowned stable water isotope laboratories that produced isotope data with the overall highest uncertainty of 0.09 ‰ for δ18O and 0.8 ‰ for δD. This unique dataset shows the strongest δ18O variability closest to the surface, damped and delayed variations in the lowest layer, and a trend towards increasing homogeneity towards the end of the season, especially in the deepest layer. Additional information on the snow height and its temporal changes suggests a non-uniform spatial imprint of the seasonal climatic information in this area, potentially following the stratigraphic noise of the surface. The data can be used to study the relation between snow height (changes) and the imprint and preservation of the isotopic composition at a site with 10–14 cm w.e. yr−1 accumulation. The high-temporal-resolution sampling allows additional analyses on (post-)depositional processes, such as vapour–snow exchange. The data can be accessed at https://doi.org/10.1594/PANGAEA.956626 (Zuhr et al., 2023a). 〈/jats:p〉
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  • 56
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    Comparing estimation techniques for temporal scaling in palaeoclimate time series (2021)
    Copernicus Publications
    In:  EPIC3Nonlinear Processes in Geophysics, Copernicus Publications, 28(3), pp. 311-328, ISSN: 1023-5809
    Details
    Publication Date: 2024-04-29
    Description: Characterizing the variability across timescales is important for understanding the underlying dynamics of the Earth system. It remains challenging to do so from palaeoclimate archives since they are more often than not irregular, and traditional methods for producing timescale-dependent estimates of variability, such as the classical periodogram and the multitaper spectrum, generally require regular time sampling. We have compared those traditional methods using interpolation with interpolation-free methods, namely the Lomb-Scargle periodogram and the first-order Haar structure function. The ability of those methods to produce timescale-dependent estimates of variability when applied to irregular data was evaluated in a comparative framework, using surrogate palaeo-proxy data generated with realistic sampling. The metric we chose to compare them is the scaling exponent, i.e. the linear slope in log-transformed coordinates, since it summarizes the behaviour of the variability across timescales. We found that, for scaling estimates in irregular time series, the interpolation-free methods are to be preferred over the methods requiring interpolation as they allow for the utilization of the information from shorter timescales which are particularly affected by the irregularity. In addition, our results suggest that the Haar structure function is the safer choice of interpolation-free method since the Lomb-Scargle periodogram is unreliable when the underlying process generating the time series is not stationary. Given that we cannot know a priori what kind of scaling behaviour is contained in a palaeoclimate time series, and that it is also possible that this changes as a function of timescale, it is a desirable characteristic for the method to handle both stationary and non-stationary cases alike.
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  • 57
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    A Snapshot on the Buildup of the Stable Water Isotopic Signal in the Upper Snowpack at EastGRIP on the Greenland Ice Sheet (2023)
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research Earth Surface, American Geophysical Union (AGU), 128(2), ISSN: 2169-9003
    Details
    Publication Date: 2024-04-29
    Description: The stable water isotopic composition in firn and ice cores provides valuable information on past climatic conditions. Because of uneven accumulation and post-depositional modifications on local spatial scales up to hundreds of meters, time series derived from adjacent cores differ significantly and do not directly reflect the temporal evolution of the precipitated snow isotopic signal. Hence, a characterization of how the isotopic profile in the snow develops is needed to reliably interpret the isotopic variability in firn and ice cores. By combining digital elevation models of the snow surface and repeated high-resolution snow sampling for stable water isotope measurements of a transect at the East Greenland Ice-core Project campsite on the Greenland Ice Sheet, we are able to visualize the buildup and post-depositional changes of the upper snowpack across one summer season. To this end, 30 cm deep snow profiles were sampled on six dates at 20 adjacent locations along a 40 m transect. Near-daily photogrammetry provided snow height information for the same transect. Our data shows that erosion and redeposition of the original snowfall lead to a complex stratification in the δ18O signature. Post-depositional processes through vapor-snow exchange affect the near surface snow with d-excess showing a decrease in surface and near-surface layers. Our data suggests that the interplay of stratigraphic noise, accumulation intermittency, and local post-depositional processes form the proxy signal in the upper snowpack.
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  • 58
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    A spectral approach to estimating the timescale-dependent uncertainty of paleoclimate records – Part 1: Theoretical concept (2020)
    Copernicus Publications
    In:  EPIC3Climate of the Past, Copernicus Publications, 16(4), pp. 1469-1492, ISSN: 1814-9324
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    Publication Date: 2024-04-29
    Description: Proxy records represent an invaluable source of information for reconstructing past climatic variations, but they are associated with considerable uncertainties. For a systematic quantification of these reconstruction errors, however, knowledge is required not only of their individual sources but also of their auto-correlation structure as this determines the timescale dependence of their magnitude, an issue that has been often ignored until now. Here a spectral approach to uncertainty analysis is provided for paleoclimate reconstructions obtained from single sediment proxy records. The formulation in the spectral domain rather than the time domain allows for an explicit demonstration and quantification of the timescale dependence that is inherent in any proxy-based reconstruction uncertainty. This study is published in two parts. In this first part, the theoretical concept is presented, and analytic expressions are derived for the power spectral density of the reconstruction error of sediment proxy records. The underlying model takes into account the spectral structure of the climate signal, seasonal and orbital variations, bioturbation, sampling of a finite number of signal carriers, and uncorrelated measurement noise, and it includes the effects of spectral aliasing and leakage. The uncertainty estimation method, based upon this model, is illustrated by simple examples. In the second part of this study, published separately, the method is implemented in an application-oriented context, and more detailed examples are presented.
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    Precession and obliquity forcing of the South African monsoon revealed by sub-tropical fires (2023)
    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 310, pp. 108128-108128, ISSN: 0277-3791
    Details
    Publication Date: 2024-04-29
    Description: While the influence of precession on monsoon at low latitudes through insolation forcing is well-known, the role of obliquity is still debated since its influence on the distribution of incoming solar radiation is small in these regions. In southern Africa, long marine and terrestrial sedimentary records attest of a precessional influence on the South African monsoon at orbital time scale. The obliquity signal is occasionally observed in the geological records although modeling results suggest an influence of precession and obliquity on summer monsoon. Here, we present a record of microscopic charcoal from core MD96-2098 located off Namibia covering the past 184,000 years. Our record of fire activity reveals cyclic changes at frequencies of 23, 58 and 12 kyr−1 and lacks the obliquity signal at 41 kyr−1. Changes in fire over southern Africa are interpreted as shifts in large and intense fires spreading in open-grassland savanna as a result of orbitally-driven changes in rainfall intensity associated with the South African monsoon. We show that, despite the absence of a 41 kyr obliquity imprint, the presence of 23, 58 and 12 kyr−1 frequencies likely stems from a nonlinear response of fire to precipitation controlled by a combination of precession and obliquity frequencies, supporting the influence of obliquity on the South African monsoon.
    Repository Name: EPIC Alfred Wegener Institut
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    Shear margins in upper half of Northeast Greenland Ice Stream were established two millennia ago (2024)
    Springer Science and Business Media LLC
    In:  EPIC3Nature Communications, Springer Science and Business Media LLC, 15(1), pp. 1193-, ISSN: 2041-1723
    Details
    Publication Date: 2024-04-29
    Description: Only a few localised ice streams drain most of the ice from the Greenland Ice Sheet. Thus, understanding ice stream behaviour and its temporal variability is crucially important to predict future sea-level change. The interior trunk of the 700 km-long North-East Greenland Ice Stream (NEGIS) is remarkable due to the lack of any clear bedrock channel to explain its presence. Here, we present a 3-dimensional analysis of the folding and advection of its stratigraphic horizons, which shows that the localised flow and shear margins in the upper NEGIS were fully developed only ca 2000 years ago. Our results contradict the assumption that the ice stream has been stable throughout the Holocene in its current form and show that upper NEGIS-type development of ice streaming, with distinct shear margins and no bed topography relationship, can be established on time scales of hundreds of years, which is a major challenge for realistic mass-balance and sea-level rise projections.
    Repository Name: EPIC Alfred Wegener Institut
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    Last Interglacial decadal sea surface temperature variability in the eastern Mediterranean (2022)
    Springer Nature
    In:  EPIC3Nature Geoscience, Springer Nature, 15(10), pp. 812-818, ISSN: 1752-0894
    Details
    Publication Date: 2024-04-29
    Description: The Last Interglacial (~129,000–116,000 years ago) is the most recent geologic period with a warmer-than-present climate. Proxy-based temperature reconstructions from this interval can help contextualize natural climate variability in our currently warming world, especially if they can define changes on decadal timescales. Here, we established a ~4.800-year-long record of sea surface temperature (SST) variability from the eastern Mediterranean Sea at 1–4-year resolution by applying mass spectrometry imaging of long-chain alkenones to a finely laminated organic-matter-rich sapropel deposited during the Last Interglacial. We observe the highest amplitude of decadal variability in the early stage of sapropel deposition, plausibly due to reduced vertical mixing of the highly stratified water column. With the subsequent reorganization of oceanographic conditions in the later stage of sapropel deposition, when SST forcing resembled the modern situation, we observe that the maximum amplitude of reconstructed decadal variability did not exceed the range of the recent period of warming climate. The more gradual, centennial SST trends reveal that the maximal centennial scale SST increase in our Last Interglacial record is below the projected temperature warming in the twenty-first century.
    Repository Name: EPIC Alfred Wegener Institut
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    Testing the consistency of Holocene and Last Glacial Maximum spatial correlations in temperature proxy records (2021)
    Wiley
    In:  EPIC3Journal of Quaternary Science, Wiley, 36(1), pp. 20-28, ISSN: 0267-8179
    Details
    Publication Date: 2024-04-29
    Description: Holocene temperature proxy records are commonly used in quantitative synthesis and model-data comparisons. However, comparing correlations between time series from records collected in proximity to one another with the expected correlations based on climate model simulations indicates either regional or noisy climate signals in Holocene temperature proxy records. In this study, we evaluate the consistency of spatial correlations present in Holocene proxy records with those found in data from the Last Glacial Maximum (LGM). Specifically, we predict correlations expected in LGM proxy records if the only difference to Holocene correlations would be due to more time uncertainty and more climate variability in the LGM. We compare this simple prediction to the actual correlation structure in the LGM proxy records. We found that time series data of ice-core stable isotope records and planktonic foraminifera Mg/Ca ratios were consistent between the Holocene and LGM periods, while time series of Uk'37 proxy records were not as we found no correlation between nearby LGM records. Our results support the finding of highly regional or noisy marine proxy records in the compilation analysed here and suggest the need for further studies on the role of climate proxies and the processes of climate signal recording and preservation.
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    Frequency-Dependent Estimation of Effective Spatial Degrees of Freedom (2021)
    American Meteorological Society
    In:  EPIC3Journal of Climate, American Meteorological Society, 34(18), pp. 7373-7388, ISSN: 0894-8755
    Details
    Publication Date: 2024-04-29
    Description: Climate variability occurs over wide ranges of spatial and temporal scales. It exhibits a complex spatial covariance structure, which depends on geographic location (e.g., tropics vs extratropics) and also consists of a superposition of (i) components with gradually decaying positive correlation functions and (ii) teleconnections that often involve anticorrelations. In addition, there are indications that the spatial covariance structure depends on frequency. Thus, a comprehensive assessment of the spatiotemporal covariance structure of climate variability would require an extensive set of statistical diagnostics. Therefore, it is often desirable to characterize the covariance structure by a simple summarizing metric that is easy to compute from datasets. Such summarizing metrics are useful, for example, in the context of comparisons between climate models or between models and observations. Here we introduce a frequency-dependent version of a simple measure of the effective spatial degrees of freedom. The measure is based on the temporal variance of the global average of some climate variable, and its novel aspect consists in its frequency dependence. We also provide a clear geometric interpretation of the measure. Its easy applicability is demonstrated using near-surface temperature and precipitation fields obtained from a paleoclimate model simulation. This application reveals a distinct scaling behavior of the spatial degrees of freedom as a function of frequency, ranging from monthly to millennial scales.
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    No detectable influence of the carbonate ion effect on changes in stable carbon isotope ratios (δ13C) of shallow dwelling planktic foraminifera over the past 160 kyr (2024)
    Copernicus GmbH
    In:  EPIC3Climate of the Past, Copernicus GmbH, 20(4), pp. 991-1015, ISSN: 1814-9332
    Details
    Publication Date: 2024-04-29
    Description: Laboratory experiments showed that the isotopic fractionation of δ13C and of δ18O during calcite formation of planktic foraminifera are species-specific functions of ambient CO32- concentration. This effect became known as the carbonate ion effect (CIE), whose role for the interpretation of marine sediment data will be investigated here in an in-depth analysis of the 13C cycle. For this investigation, we constructed new 160 kyr long mono-specific stacks of changes in both δ13C and δ18O from either the planktic foraminifera Globigerinoides ruber (rub) or Trilobatus sacculifer (sac) from 112 and 40 marine records, respectively, from the wider tropics (latitudes below 38°). Both mono-specific time series Δ(δ13Crub) and Δ(δ13Csac) are very similar to each other, and a linear regression through a scatter plot of both data sets has a slope of ∼ 0.99 – although the laboratory-based CIE for both species differs by a factor of nearly 2, implying that they should record distinctly different changes in δ13C, if we accept that the carbonate ion concentration changes on glacial–interglacial timescales. For a deeper understanding of the 13C cycle, we use the Solid Earth version of the Box model of the Isotopic Carbon cYCLE (BICYLE-SE) to calculate how surface-ocean CO32- should have varied over time in order to be able to calculate the potential offsets which would by caused by the CIE quantified in culture experiments. Our simulations are forced with atmospheric reconstructions of CO2 and δ13CO2 derived from ice cores to obtain a carbon cycle which should at least at the surface ocean be as close as possible to expected conditions and which in the deep ocean largely agrees with the carbon isotope ratio of dissolved inorganic carbon (DIC), δ13CDIC, as reconstructed from benthic foraminifera. We find that both Δ(δ13Crub) and Δ(δ13Csac) agree better with changes in simulated δ13CDIC when ignoring the CIE than those time series which were corrected for the CIE. The combination of data- and model-based evidence for the lack of a role for the CIE in Δ(δ13Crub) and Δ(δ13Csac) suggests that the CIE as measured in laboratory experiments is not directly transferable to the interpretation of marine sediment records. The much smaller CIE-to-glacial–interglacial-signal ratio in foraminifera δ18O, when compared to δ13C, prevents us from drawing robust conclusions on the role of the CIE in δ18O as recorded in the hard shells of both species. However, theories propose that the CIE in both δ13C and δ18O depends on the pH in the surrounding water, suggesting that the CIE should be detectable in neither or both of the isotopes. Whether this lack of role of the CIE in the interpretation of planktic paleo-data is a general feature or is restricted to the two species investigated here needs to be checked with further data from other planktic foraminiferal species.
    Repository Name: EPIC Alfred Wegener Institut
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    Amazonia through time: Andean uplift, climate change, landscape evolution and biodiversity (2010)
    In:  Science vol. 330 no. 6006, pp. 927-931
    Details
    Publication Date: 2024-04-29
    Description: The Amazonian rainforest is arguably the most species-rich terrestrial ecosystem in the world, yet the timing of the origin and volutionary causes of this diversity are a matter of debate. We review the geologic and phylogenetic evidence from Amazonia and compare it with uplift records from the Andes. This uplift and its effect on regional climate fundamentally changed the Amazonian landscape by reconfiguring drainage patterns and creating a vast influx of sediments into the basin. On this “Andean” substrate, a region-wide edaphic mosaic developed that became extremely rich in species, particularly in Western Amazonia. We show that Andean uplift was crucial for the evolution of Amazonian landscapes and ecosystems, and that current biodiversity patterns are rooted deep in the pre-Quaternary.
    Keywords: Amazonia ; evolution ; biodiversity
    Repository Name: National Museum of Natural History, Netherlands
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    Mating genes in Calonectria and evidence for a heterothallic ancestral state (2020)
    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 45, pp. 163-176
    Details
    Publication Date: 2024-04-29
    Description: The genus Calonectria includes many important plant pathogens with a wide global distribution. In order to better understand the reproductive biology of these fungi, we characterised the structure of the mating type locus and flanking genes using the genome sequences for seven Calonectria species. Primers to amplify the mating type genes in other species were also developed. PCR amplification of the mating type genes and multi-gene phylogenetic analyses were used to investigate the mating strategies and evolution of mating type in a collection of 70 Calonectria species residing in 10 Calonectria species complexes. Results showed that the organisation of the MAT locus and flanking genes is conserved. In heterothallic species, a novel MAT gene, MAT1-2-12 was identified in the MAT1-2 idiomorph; the MAT1-1 idiomorph, in most cases, contained the MAT1-1-3 gene. Neither MAT1-1-3 nor MAT1-2-12 was found in homothallic Calonectria (Ca.) hongkongensis, Ca. lateralis, Ca. pseudoturangicola and Ca. turangicola. Four different homothallic MAT locus gene arrangements were observed. Ancestral state reconstruction analysis provided evidence that the homothallic state was basal in Calonectria and this evolved from a heterothallic ancestor.
    Keywords: Ecology ; Evolution ; Behavior and Systematics ; Cylindrocladium ; fungal biology ; fungal pathogens ; MAT locus ; mating type ; phylogeny ; sexual reproduction
    Repository Name: National Museum of Natural History, Netherlands
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    Assessment of the correlation between site-specific nonlinear soil behavior for Japanese KiK-net stations and geological, geotechnical parameters (2024)
    In:  Abstracts
    Details
    Publication Date: 2024-04-29
    Language: English
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    Slow-Slip Earthquakes observations in Costa Rica and their Potential Impact on Seismic Hazard Assessments (2024)
    In:  Abstracts
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    Publication Date: 2024-04-29
    Language: English
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    Ground motion prediction using Physics-Informed Symbolic Learning (PISL) (2024)
    In:  Abstracts
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    The recent crustal stress state of Germany - results of a new geomechanical–numerical model (2024)
    In:  Abstracts
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    Publication Date: 2024-04-29
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    Earthquake loss assessments methods - Comparison and new developments shown on past and future earthquake scenarios for Iran (2024)
    In:  Abstracts
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    Publication Date: 2024-04-29
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    An Estimate of the Effect of 3D Heterogeneous Density Distribution on Coseismic Deformation Using a Spectral Finite-Element Approach (2023)
    In:  International Association of Geodesy Symposia
    Details
    Publication Date: 2024-04-29
    Description: The advancement of the Global Geodetic Observing System (GGOS) has enabled monitoring of mass transport and solid-Earth deformation processes with unprecedented accuracy. Coseismic deformation is modelled as an elastic response of the solid Earth to an internal dislocation. Self-gravitating spherical Earth models can be employed in modelling regional to global scale deformations. Recent seismic tomography and high-pressure/high-temperature experiments have revealed finer-scale lateral heterogeneities in the elasticity and density structures within the Earth, which motivates us to quantify the effects of such finer structures on coseismic deformation. To achieve this, fully numerical approaches including the Finite Element Method (FEM) have often been used. In our previous study, we presented a spectral FEM, combined with an iterative perturbation method, to consider lateral heterogeneities in the bulk and shear moduli for surface loading. The distinct feature of this approach is that the deformation of the entire sphere is modelled in the spectral domain with finite elements dependent only on the radial coordinate. By this, self-gravitation can be treated without special treatments employed when using an ordinary FEM. In this study, we extend the formulation so that it can deal with lateral heterogeneities in density in the case of coseismic deformation. We apply this approach to a longer-wavelength vertical deformation due to a large earthquake. The result shows that the deformation for a laterally heterogeneous density distribution is suppressed mainly where the density is larger, which is consistent with the fact that self-gravitation reduces longer-wavelength deformations for 1-D models. The effect on the vertical displacement is relatively small, but the effect on the gravity change could amount to the same order of magnitude of a given heterogeneity if the horizontal scale of the heterogeneity is large enough.
    Language: English
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    Failures, successes and challenges of machine-learning-based engineering ground-motion models (2024)
    In:  Abstracts
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    Temporal evolution of resonance frequencies as a proxy to monitor nonlinear site response: a case study using KiK-net data in Japan (2024)
    In:  Abstracts
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    Publication Date: 2024-04-29
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    ICDP Primer - Planning, Managing, and Executing Continental Scientific Drilling Projects (2024)
    GFZ German Research Centre for Geosciences
    Details
    Publication Date: 2024-04-29
    Description: Present day system Earth research utilizes the tool ‘Scientific Drilling’ to access samples and to monitor deep Earth processes that cannot be tackled by other scientific means. Unlike most laboratory experiments or computer modelling, drilling projects are massive field endeavours requiring intense collaboration of researchers with engineers and service providers. In the framework of the International Continental Scientific Drilling Program, ICDP, more than seventy drilling projects have been conducted, from multiyear big research programs to short, smallscale deployments such as lake drilling projects. ICDP has supported these projects not only through grants covering field-related costs, but also through a variety of scientific-technical services and support, as well as active help in data management, outreach and publication. These services are described in this booklet. Due to its instructional character, we call it the ICDP Primer.
    Language: English
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    Complete mitochondrial genome MK992912 of Great Knot (Calidris tenuirostris) is a chimera with DNA from Pacific Golden Plover Pluvialis fulva (Aves: Charadriiformes) (2024)
    In:  Mitochondrial DNA Part B vol. 9 no. 4, pp. 532-535
    Details
    Publication Date: 2024-04-28
    Description: A complete mitochondrial genome of Great Knot (Calidris tenuirostris), MK992912, was published by He and colleagues in 2020. Here we show that this mitogenome is actually a chimera containing DNA fragments of both C. tenuirostris (15,567 bp, 92.8%) and Pacific Golden Plover (Pluvialis fulva, 1208 bp, 7.2%). Detecting such errors is possible before publication if each sequenced fragment is separately analyzed phylogenetically before assembling the fragments into a single mitogenome. This mitogenome has been re-used in at least four phylogenies. The error is documented to avoid the perpetuation of erroneous sequence information in the literature.
    Keywords: Chimerism ; laboratory ; errors ; mitogenome ; sequence artifacts ; shorebirds
    Repository Name: National Museum of Natural History, Netherlands
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    A new, unusually large, Clavicornaltica Scherer, 1974 flea beetle from Borneo, described and sequenced in the field by citizen scientists (Coleoptera, Chrysomelidae, Galerucinae) (2024)
    Pensoft Publishers
    In:  Biodiversity Data Journal vol. 12 no. e119481
    Details
    Publication Date: 2024-04-28
    Description: Background: The genus Clavicornaltica Scherer 1974 consists of very small, soil-dwelling flea beetles in South, Southeast and East Asia. Due to their diminutive size and morphological similarities, very little is known about their ecology and taxonomical diversity. It is likely that further studies will reveal this genus to be much more speciose than the 30 species currently recognised. New information: A new species of Clavicornaltica from Brunei Darussalam is described, C. mataikanensis Otani et al., sp. nov. This is the second species of this genus recorded from Ulu Temburong National Park.
    Keywords: Lowland Dipterocarp rainforest ; citizen science ; new species ; humicole beetles ; taxonomy ; tourism
    Repository Name: National Museum of Natural History, Netherlands
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    Efficient Speech Detection in Environmental Audio Using Acoustic Recognition and Knowledge Distillation (2024)
    In:  Sensors vol. 24 no. 7, pp. 2046-2046
    Details
    Publication Date: 2024-04-28
    Description: The ongoing biodiversity crisis, driven by factors such as land-use change and global warming, emphasizes the need for effective ecological monitoring methods. Acoustic monitoring of biodiversity has emerged as an important monitoring tool. Detecting human voices in soundscape monitoring projects is useful both for analyzing human disturbance and for privacy filtering. Despite significant strides in deep learning in recent years, the deployment of large neural networks on compact devices poses challenges due to memory and latency constraints. Our approach focuses on leveraging knowledge distillation techniques to design efficient, lightweight student models for speech detection in bioacoustics. In particular, we employed the MobileNetV3-Small-Pi model to create compact yet effective student architectures to compare against the larger EcoVADteacher model, a well-regarded voice detection architecture in eco-acoustic monitoring. The comparative analysis included examining various configurations of the MobileNetV3-Small-Pi-derived student models to identify optimal performance. Additionally, a thorough evaluation of different distillation techniques was conducted to ascertain the most effective method for model selection. Our findings revealed that the distilled models exhibited comparable performance to the EcoVAD teacher model, indicating a promising approach to overcoming computational barriers for real-time ecological monitoring.
    Keywords: passive acoustic monitoring ; eco-acoustics ; deep learning ; knowledge distillation ; bioacoustics ; classification ; transfer learning ; speech detection
    Repository Name: National Museum of Natural History, Netherlands
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    Diachronic quantification of the local marine reservoir effect (MRE) using Loripes orbiculatus shells from Late Holocene lagoonal deposits at Puntone di Scarlino (Central Tuscany, Italy): Proposed roles of microbial diagenesis and sedimentation rates (2024)
    In:  Quaternary Geochronology vol. 81 no. 101505
    Details
    Publication Date: 2024-04-28
    Description: With the aim of dating the early salt production at Puntone di Scarlino (Central Tuscany, Italy) and establishing the environmental history of this coastal site, a sediment core was studied, taken from the lagoon next to the archaeological site. Diachronic radiocarbon dating of terrestrial plant macro remains and Loripes orbiculatus (Poli, 1795) shells, a burrowing lucinid bivalve occurring throughout the sediment cored, revealed a Marine Reservoir Effect (MRE) that varied markedly over time. Between ca. 4000 and 2500 cal BP, the △R values ranged between −50 and + 500 14C years, thus rendering the Loripes shells truly unsuited for independent radiocarbon dating. Extensive geochemical and palaeoecological study of the core and its environment showed that none of the ubiquitous explanations for this highly variable MRE, such as ‘hard water’ or ‘upwelling old seawater’, can be valid. We attribute the phenomenon to the uptake by this lucinid mollusc of ‘old carbon’ from the sediment column into which it had burrowed, released by diagenetic microbial decomposition processes such as methanogenesis. The age of this inorganic carbon varied, being linked to the sedimentation rate: with decreasing sedimentation rate its impact will increase, whereas at high sedimentation rates its impact will likely be minimal. Our results raise serious doubts about the suitability for radiocarbon dating of benthic fauna from shallow coastal environments and point at these diagenetic processes as potentially important sources of ‘old carbon’.
    Keywords: Holocene ; Paleoceanography ; Europe ; Radiogenic isotopes ; Marine reservoir effect ; Loripes orbiculatus ; Diagenetic carbon flux
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    Illuminating type collections of nectriaceous fungi in Saccardo's fungarium (2020)
    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 45, pp. 221-249
    Details
    Publication Date: 2024-04-28
    Description: Specimens of Nectria spp. and Nectriella rufofusca were obtained from the fungarium of Pier Andrea Saccardo, and investigated via a morphological and molecular approach based on MiSeq technology. ITS1 and ITS2 sequences were successfully obtained from 24 specimens identified as ‘Nectria’ sensu Saccardo (including 20 types) and from the type specimen of Nectriella rufofusca. For Nectria ambigua, N. radians and N. tjibodensis only the ITS1 sequence was recovered. On the basis of morphological and molecular analyses new nomenclatural combinations for Nectria albofimbriata, N. ambigua, N. ambigua var. pallens, N. granuligera, N. peziza subsp. reyesiana, N. radians, N. squamuligera, N. tjibodensis and new synonymies for N. congesta, N. flageoletiana, N. phyllostachydis, N. sordescens and N. tjibodensis var. crebrior are proposed. Furthermore, the current classification is confirmed for Nectria coronata, N. cyanostoma, N. dolichospora, N. illudens, N. leucotricha, N. mantuana, N. raripila and Nectriella rufofusca. This is the first time that these more than 100-yr-old specimens are subjected to molecular analysis, thereby providing important new DNA sequence data authentic for these names.
    Keywords: Ecology ; Evolution ; Behavior and Systematics ; ancient DNA ; Ascomycota ; Hypocreales ; Illumina ; ribosomal sequences ; Sordariomycetes
    Repository Name: National Museum of Natural History, Netherlands
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    The InBIO Barcoding Initiative Database: DNA barcodes of Iberian Bees (2024)
    Pensoft Publishers
    In:  Biodiversity Data Journal vol. 12 no. e117172
    Details
    Publication Date: 2024-04-28
    Description: Bees are important actors in terrestrial ecosystems and are recognised for their prominent role as pollinators. In the Iberian Peninsula, approximately 1,100 bee species are known, with nearly 100 of these species being endemic to the Peninsula. A reference collection of DNA barcodes, based on morphologically identified bee specimens, representing 514 Iberian species, was constructed. The "InBIO Barcoding Initiative Database: DNA Barcodes of Iberian bees" dataset contains records of 1,059 sequenced specimens. The species of this dataset correspond to about 47% of Iberian bee species diversity and 21% of endemic species diversity. For peninsular Portugal only, the corresponding coverage is 71% and 50%. Specimens were collected between 2014 and 2022 and are deposited in the research collection of Thomas Wood (Naturalis Biodiversity Center, The Netherlands), in the FLOWer Lab collection at the University of Coimbra (Portugal), in the Andreia Penado collection at the Natural History and Science Museum of the University of Porto (MHNC-UP) (Portugal) and in the InBIO Barcoding Initiative (IBI) reference collection (Vairão, Portugal).
    Keywords: Hymenoptera ; occurrence records ; species distributions ; peninsular Portugal ; peninsular ; Spain ; DNA barcode ; cytochrome c oxidase subunit I (COI) ; pollinator
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    Cryphonectriaceae on Myrtales in China: phylogeny, host range, and pathogenicity (2020)
    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 45, pp. 101-131
    Details
    Publication Date: 2024-04-28
    Description: Plantation-grown Eucalyptus (Myrtaceae) and other trees residing in the Myrtales have been widely planted in southern China. These fungal pathogens include species of Cryphonectriaceae that are well-known to cause stem and branch canker disease on Myrtales trees. During recent disease surveys in southern China, sporocarps with typical characteristics of Cryphonectriaceae were observed on the surfaces of cankers on the stems and branches of Myrtales trees. In this study, a total of 164 Cryphonectriaceae isolates were identified based on comparisons of DNA sequences of the partial conserved nuclear large subunit (LSU) ribosomal DNA, internal transcribed spacer (ITS) regions including the 5.8S gene of the ribosomal DNA operon, two regions of the β-tubulin (tub2/tub1) gene, and the translation elongation factor 1-alpha (tef1) gene region, as well as their morphological characteristics. The results showed that eight species reside in four genera of Cryphonectriaceae occurring on the genera Eucalyptus, Melastoma (Melastomataceae), Psidium (Myrtaceae), Syzygium (Myrtaceae), and Terminalia (Combretaceae) in Myrtales. These fungal species include Chrysoporthe deuterocubensis, Celoporthe syzygii, Cel. eucalypti, Cel. guangdongensis, Cel. cerciana, a new genus and two new species, as well as one new species of Aurifilum. These new taxa are hereby described as Parvosmorbus gen. nov., Par. eucalypti sp. nov., Par. guangdongensis sp. nov., and Aurifilum terminali sp. nov. Pathogenicity tests showed that the eight species of Cryphonectriaceae are pathogenic to two Eucalyptus hybrid seedlings, Melastoma sanguineum branches, and Psidium guajava and Syzygium jambos seedlings. The overall data showed that Chr. deuterocubensis is the most aggressive, followed by Par. eucalypti. Significant differences in tolerance were observed between the two tested Eucalyptus hybrid genotypes, suggesting that disease-tolerant genotypes can be selected for disease management in the Eucalyptus industry.
    Keywords: Ecology ; Evolution ; Behavior and Systematics ; Eucalyptus ; fungal pathogen ; host jump ; Myrtaceae ; new taxa ; plantation forestry
    Repository Name: National Museum of Natural History, Netherlands
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    RADReef: A global Holocene Reef Rate of Accretion Dataset (2024)
    In:  Scientific Data vol. 11 no. 398
    Details
    Publication Date: 2024-04-28
    Description: Reef cores are a powerful tool for investigating temporal changes in reef communities. Radiometric dating facilitates the determination of vertical accretion rates, which has allowed for examination of local-regional controlling factors, such as subsidence and sea level changes. Coral reefs must grow at sufcient rates to keep up with sea level rise, or risk ‘drowning.’ As sea level is expected to rise signifcantly in the next 100 years and beyond, it is important to understand whether reefs will be able to survive. Historical records of reef accretion rates extracted from cores provide valuable insights into extrinsic controlling factors of reef growth and are instrumental in helping predict if future reefs can accrete at rates needed to overcome predicted sea level changes. While extensive research exists at local and regional scales, limited attention has been given to identifying global patterns and drivers. To address this, we present “RADReef”: A global dataset of dated Holocene reef cores. RADReef serves as a foundation for further research on past, present and future reef accretion.
    Keywords: Biogeochemistry ; Geomorphology ; Palaeoceanography ; Physical oceanography
    Repository Name: National Museum of Natural History, Netherlands
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    Critical transitions in the Amazon forest system (2024)
    In:  Nature vol. 626 no. 7999, pp. 555-564
    Details
    Publication Date: 2024-04-28
    Description: The possibility that the Amazon forest system could soon reach a tipping point, inducing large-scale collapse, has raised global concern. For 65 million years, Amazonian forests remained relatively resilient to climatic variability. Now, the region is increasingly exposed to unprecedented stress from warming temperatures, extreme droughts, deforestation and fires, even in central and remote parts of the system. Long existing feedbacks between the forest and environmental conditions are being replaced by novel feedbacks that modify ecosystem resilience, increasing the risk of critical transition. Here we analyse existing evidence for five major drivers of water stress on Amazonian forests, as well as potential critical thresholds of those drivers that, if crossed, could trigger local, regional or even biome-wide forest collapse. By combining spatial information on various disturbances, we estimate that by 2050, 10% to 47% of Amazonian forests will be exposed to compounding disturbances that may trigger unexpected ecosystem transitions and potentially exacerbate regional climate change. Using examples of disturbed forests across the Amazon, we identify the three most plausible ecosystem trajectories, involving diferent feedbacks and environmental conditions. We discuss how the inherent complexity of the Amazon adds uncertainty about future dynamics, but also reveals opportunities for action. Keeping the Amazon forest resilient in the Anthropocene will depend on a combination of local eforts to end deforestation and degradation and to expand restoration, with global eforts to stop greenhouse gas emissions.
    Repository Name: National Museum of Natural History, Netherlands
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    Boletín CTN Diocean No. 3 / 2023 (2024)
    Comisión Colombiana del Océano | Bogotá D.C., Colombia
    Details
    Publication Date: 2024-04-27
    Description: Hace tres años atrás el Comité Técnico Nacional de Coordinación de Datos e Información Oceánicos (CTN Diocean) de la Comisión Colombiana del Océano (CCO), estableció un plan de trabajo que abarca cinco años de actividades institucionales para fortalecer la gestión de estos importantes activos del país. Para entonces se tuvieron en cuenta diferentes estrategias como línea base para definir las tareas a desarrollar, y en la actualidad es gratificante para miembros e invitados permanentes confirmar, que lo planeado sigue vigente y acorde con los desafíos del ‘Decenio de las Ciencias Oceánicas para el Desarrollo Sostenible’, las necesidades de la comunidad y los recientes lineamientos de política nacionales e internacionales. En el presente número del Boletín CTN Diocean, se destacan entre otros, dos reconocimientos logrados en el nivel internacional por parte de instituciones que hacen parte del comité y que le aportan al fortalecimiento de la gestión de datos oceánicos de Colombia: el primero, los datos abiertos oceanográficos como una actividad del ‘Decenio de las Ciencias Oceánicas para el Desarrollo Sostenible’ de la Comisión Oceanográfica Intergubernamental (COI); y el segundo, la copresidencia para el periodo entre sesiones 2023-2025 del programa para el Intercambio Internacional de Datos Oceanográficos (COI-IODE) junto con Suecia, en el marco de la cual se inició la asesoría con nuestros hermanos panameños en la materia.
    Description: Published
    Description: Not Known
    Keywords: Acceso abierto ; Usuario de información ; Gestión de la información ; Base de datos ; Sistema de información ; Organización y gestión ; ASFA_2015::G::Geographic information systems ; ASFA_2015::I::Information centres ; ASFA_2015::D::Databases ; ASFA_2015::I::Information handling
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    Efeitos de ações antrópicas sobre as interações bióticas entre os peixes de uma planície de inundação Neotropical: alterações nos padrões de coocorrência de espécies. (2024)
    Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais
    Details
    Publication Date: 2024-04-27
    Description: The freshwater ichthyofauna is largely threatened by the anthropogenic impacts in these ecosystems. The climatic changes caused by human actions and dams’ constructions concerningly affects the freshwater fishes, including its biotic interactions network. Thus, this work aimed at evaluating the Upper Paraná River floodplain’s (UPRF) ichthyofauna under the impacts caused by climate changes, years of extreme drought an extreme flood, and under the impacts caused by the construction of an upstream dam, the Sérgio Motta Hydroelectric Power Plant, Brazil. The sampled years were classified in extreme drought, neutral and extreme flood, according to the predominant characteristics of its hydrological regime, and in pré-damming years, before the upstream hydroelectric power plant construction and reservoir’s flooding, and post-damming years. The abiotic and hydrometric variables were concurrently sampled with the abundance of fish species, allowing to exclude the environmental variables’ effects over the species’ cooccurrence, using multivariate generalized linear models with latent variables. The force of the interspecific biotic interactions was obtained through cooccurrence values for each pair of species, visualized through negative, neutral, and positive values. Regarding the results involving the hydrological regime influence, it was observed differences between drought, neutral and flood years, with stronger cooccurrence values between the UPRF’s ichthyofauna in drought years (for positive and negative values). Regarding the results involving the construction of the UPRF’s upstream dam, it was observed differences comparing the pré-damming and post-damming years cooccurrence patters, with predominantly positive values in post-damming years, and predominantly neutral cooccurrences in pré-damming years. These work results indicate the increment of the cooccurrence values between a floodplain’s fish species due to extreme droughts and upstream dams’ constructions, once the cooccurrence values were more intense under these conditions. Stands out the importance of biotic interactions for the elaboration of management plans and freshwater species conservation in response to anthropogenic actions.
    Description: A ictiofauna de ambientes de água doce se encontra amplamente ameaçada por ações antrópicas. As mudanças climáticas e a construção de barragens afetam os peixes de água doce e suas redes de interações bióticas. Neste contexto, este estudo avaliou a ictiofauna da planície de inundação do alto rio Paraná (PIARP) sob os impactos de mudanças climáticas, épocas de secas e cheias extremas, e sob os impactos causados pela construção de uma barragem a montante, a Usina Hidrelétrica Sérgio Motta, Brasil. Os anos amostrados foram classificados em anos de seca extrema, neutros e de cheia extrema, de acordo com as condições predominantes de seu regime hidrológico, e em anos de pré-barramento, antes da construção e inundação do reservatório da usina hidrelétrica a montante, e pós-barramento. As variáveis abióticas e variáveis hidrométricas foram amostradas concomitantemente com a abundância das espécies de peixe, permitindo excluir o efeito das variáveis ambientais sobre a ocorrência das espécies, com o uso de modelos lineares generalizados multivariados de variáveis latentes. Obteve-se a força das interações bióticas interespecíficas pelos valores de coocorrência, positivos ou negativos, entre cada par de espécies. Com relação aos resultados envolvendo a influência dos regimes hidrológicos, foram encontradas diferenças nos valores médios de coocorrência entre anos de seca extrema, anos neutros e anos de cheia extrema, indicando que os valores de coocorrência são mais fortes entre a ictiofauna da PIARP (tanto interações positivas quanto negativas) em anos de seca. Para os efeitos da construção da barragem a montante da PIARP, observou-se diferenças entre os padrões de coocorrência de espécies antes e após a sua construção, indicando valores de coocorrência predominantemente positivos no período pós-barramento, e coocorrências predominantemente neutras no período pré-barramento. Os resultados indicam incremento nos padrões de coocorrência entre as espécies de peixes da planície de inundação frente secas extremas e construção de barragens a montante, uma vez que os valores de coocorrência foram mais intensos sob essas condições. Destaca-se a importância das interações bióticas em resposta às ações antrópicas para a elaboração de planos de manejo e para a conservação das espécies de peixes de água doce.
    Description: PhD
    Keywords: Peixes de água doce ; Comunidades, Ecologia de ; Interações bióticas ; Ações antrópicas ; Coocorrência de espécies ; Variáveis ambientais ; Variáveis hidrométricas ; Generalized linear latent variable models (GLLVM) ; ASFA_2015::F::Freshwater ecology ; ASFA_2015::F::Freshwater fish ; ASFA_2015::C::Communities (ecological) ; ASFA_2015::I::Interactions ; ASFA_2015::A::Anthropogenic factors ; ASFA_2015::S::Species diversity ; ASFA_2015::E::Environmental factors ; ASFA_2015::H::Hydrometers
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    Type: Thesis/Dissertation
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    Classification of a high latitude bog using multispectral drone imagery (2023)
    In:  EPIC3
    Details
    Publication Date: 2024-04-27
    Description: Peatlands store and emit large amounts of greenhouse gases. With the climate changing due to global warming, measuring these emissions helps to get a better understanding of the role of peatlands in the global carbon cycle. Measurements at a bog site of the Siikaneva peatland show that the emissions vary along the different microtopographies shaped by their vegetation and ground water level. To upscale these measurements, a supervised classification of the study area was implemented in this study by testing a method that uses high-resolution multispectral aerial imagery, captured by a UAV (Uncrewed Aerial Vehicle), and a Random Forest classifier. A cohesive orthomosaic of the study area was produced, training data were generated to adjust the Random Forest model, and the study area was classified. The results show that the applied methods were successful in generating a multispectral orthomosaic as well as a classified raster of the study area. A mean classification accuracy of 75.7 % was achieved, which can be considered as a good result. Misclassification rates of neighboring microtopographies with similar vegetation could be mitigated by utilizing a LiDAR (Light Detection and Ranging) sensor in further studies.
    Repository Name: EPIC Alfred Wegener Institut
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    Dieback and decline pathogens of olive trees in South Africa (2020)
    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 45, pp. 196-220
    Details
    Publication Date: 2024-04-27
    Description: Trunk disease fungal pathogens reduce olive production globally by causing cankers, dieback, and other decline-related symptoms on olive trees. Very few fungi have been reported in association with olive dieback and decline in South Africa. Many of the fungal species reported from symptomatic olive trees in other countries have broad host ranges and are known to occur on other woody host plants in the Western Cape province, the main olive production region of South Africa. This survey investigated the diversity of fungi and symptoms associated with olive dieback and decline in South Africa. Isolations were made from internal wood symptoms of 145 European and 42 wild olive trees sampled in 10 and 9 districts, respectively. A total of 99 taxa were identified among 440 fungal isolates using combinations of morphological and molecular techniques. A new species of Pseudophaeomoniella, P. globosa, had the highest incidence, being recovered from 42.8 % of European and 54.8 % of wild olive samples. This species was recovered from 9 of the 10 districts where European olive trees were sampled and from all districts where wild olive trees were sampled. Members of the Phaeomoniellales (mainly P. globosa) were the most prevalent fungi in five of the seven symptom types considered, the only exceptions being twig dieback, where members of the Botryosphaeriaceae were more common, and soft/white rot where only Basidiomycota were recovered. Several of the species identified are known as pathogens of olives or other woody crops either in South Africa or elsewhere in the world, including species of Neofusicoccum, Phaeoacremonium, and Pleurostoma richardsiae. However, 81 of the 99 taxa identified have not previously been recorded on olive trees and have unknown interactions with this host. These taxa include one new genus and several putative new species, of which four are formally described as Celerioriella umnquma sp. nov., Pseudophaeomoniella globosa sp. nov., Vredendaliella oleae gen. & sp. nov., and Xenocylindrosporium margaritarum sp. nov.
    Keywords: Ecology ; Evolution ; Behavior and Systematics ; Celerioriella ; five new taxa ; Olea europaea subsp. cuspidata ; Olea europaea subsp. europaea ; phylogenetics ; Pseudophaeomoniella ; taxonomy ; Vredendaliella ; Xenocylindrosporium
    Repository Name: National Museum of Natural History, Netherlands
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    Strategies for good and comprehensive metadata in field-based permafrost research (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-26
    Description: Comprehensive metadata are key to making data FAIR. It is therefore essential to collect metadata in an organized and standardized way. For standardized data acquisition, ie. on research vessels, tools are already available and constantly improved. In land-based permafrost expeditions, however, the data and metadata are as diverse as the science questions behind them. We present an overview of this diversity in (meta)data and (meta)data collection and propose strategies to writing good and comprehensive metadata. We encourage to think about metadata right from the start and work on them steadily during the whole process from field work preparation to data collection and from data analysis to final publication. Easy to adapt templates and only choosing the tools that fit the specific data set increases the participation of the whole team.
    Repository Name: EPIC Alfred Wegener Institut
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    Late Pleistocene and Holocene Vegetation History as Inferred From Palynological Investigations of the El’gygytgyn Lake Crater Permafrost Deposits (2012)
    Institute of Geography, Russian Academy of Sciences
    In:  EPIC3Geographical series, Institute of Geography, Russian Academy of Sciences, (4), pp. 69-69, ISSN: 0373-2444
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    Publication Date: 2024-04-26
    Repository Name: EPIC Alfred Wegener Institut
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    Depositional dynamics in the El'gygytgyn Crater margin: implications for the 3.6 Ma old sediment archive (2012)
    Copernicus Publications
    In:  EPIC3Climate of the Past, Copernicus Publications, 8(6), pp. 1897-1911, ISSN: 1814-9324
    Details
    Publication Date: 2024-04-26
    Description: The combination of permafrost history and dynamics, lake level changesRussian Arctic. The purpose of this study is to propose a depositional framework based on analyses of the core strata from the lake margin and historical reconstructions from various studies at the site. A sedimentological program has been conducted using frozen core samples from the 141.5m long El’gygytgyn 5011-3 permafrost well. The drill site is located in sedimentary permafrost west of the lake that partly fills the El’gygytgyn Crater. The total core sequence is interpreted as strata building up a progradational alluvial fan delta. Four macroscopically distinct sedimentary units are identified. Unit 1 (141.5–117.0 m) is comprised of ice-cemented, matrix-supported sandy gravel and intercalated sandy layers. Sandy layers represent sediments which rained out as particles in the deeper part of the water column under highly energetic conditions. Unit 2 (117.0–24.25 m) is dominated by ice-cemented, matrix-supported sandy gravel with individual gravel layers. Most of the Unit 2 diamicton is understood to result from alluvial wash and subsequent gravitational sliding of coarse-grained (sandy gravel) material on the basin slope. Unit 3 (24.25–8.5 m) has icecemented, matrix-supported sandy gravel that is interrupted by sand beds. These sandy beds are associated with flooding events and represent near-shore sandy shoals. Unit 4 (8.5–0.0 m) is ice-cemented, matrix-supported sandy gravel with varying ice content, mostly higher than below. It consists of slope material and creek fill deposits. The uppermost metre is the active layer (i.e. the top layer of soil with seasonal freeze and thaw) into which modern soil organic matter has been incorporated. The nature of the progradational sediment transport taking place from the western and northern crater margins may be related to the complementary occurrence of frequent turbiditic layers in the central lake basin, as is known from the lake sediment record. Slope processes such as gravitational sliding and sheet flooding occur especially during spring melt and promote mass wasting into the basin. Tectonics are inferred to have initiated the fan accumulation in the first place and possibly the off-centre displacement of the crater lake.
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    Simulating climate and stable water isotopes during the Last Interglacial using a coupled climate-isotope model (2017)
    In:  EPIC3Journal of Advances in Modelling Earth Systems, ISSN: 1942-2466
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    Publication Date: 2024-04-26
    Repository Name: EPIC Alfred Wegener Institut
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    Cladoceran assemblages of the Last Interglacial obtained from permafrost lacustrine deposits exposed at the Laptev Sea coast (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-26
    Description: The cladoceran assemblages of the lacustrine deposits of the Krest-Yuryakh sequence (Marine Isotope Stage 5e, MIS5e; Last Interglacial, LIG) exposed at the southern coast of Bol’shoy Lyakhovsky Island and the Oyogos Yar mainland coast along the Dmitry Laptev Strait (Yakutia, Siberia, Russia) were investigated. Field studies on both sides of the Laptev Strait were conducted in 2002, 2007, and 2014. The vegetation of the study area is currently represented by Arctic tundra. The mean air temperature of the warmest month of the year (MTWA) is 3.5 °C for the studied sites on Bol’shoy Lyakhovsky Island and 6.9 °C for Oyogos Yar (https://www.worldclim.org; Fick and Hijmans, 2017). Age information of the Krest-Yuryakh lacustrine deposits is based on infrared-stimulated luminescence (IRSL) (Schirrmeister et al., submitted). Cladocera were studied in profile L7-11 on Bol’shoy Lyakhovsky Island and in profiles Oya-3-11, Oy7-01, Oy7-08, Oya 5-1 on Oyogos Yar.? The studied fossil cladocera remains of Krest-Yuryakh deposits are exceptionally well preserved. The overall cladocera record comprises 13 taxa. The most common species are Chydorus cf. sphaericus, Bosmina sp. and Daphnia pulex gr. The cladoceran assemblages are dominated by littoral shallow-water taxa, such as Chydorus cf. sphaericus, Alona guttata / Coronatella rectangula. However, profile L7-11 on Bol’shoy Lyakhovsky had very low concentrations of specimens of which Chydorus cf. sphaericus is the most common species. The cladoceran records on Oyogos Yar are more diverse and had much higher concentrations than those on Bol’shoy Lyakhovsky. Most of the cladoceran remains on Oyogos Yar belong to littoral phytophilous species, associated with macrophytes. In the cladoceran communities of Oyogos Yar, along with cold-water taxa, also more thermophilic taxa were found. In particular, the findings of remains of the species L. leidigi indicate much warmer conditions in the past than today. According to Flößner (2000), this species is absent nowadays in the arctic-subarctic zones, but present in the boreal zone. Thus, the modern distribution of L. leidigi is located considerably further south today. The northernmost known discovery of this species in Yakutia (northern Russia) is located in the basin of the Omoloy River (MTWA of +11.5 °C, Frolova & Nigmatullin, unpublished data).We conclude that the climatic conditions were more favorable for cladocerans on Oyogos Yar than on Bol’shoy Lyakhovsky in the Last Interglacial (LIG) sub-stage. The cladoceran assemblages of Oyogos Yar indicate lacustrine habitats with a well-developed vegetated littoral zone as well pelagic open-water zones in the paleo-lakes. Discoveries of cladoceran taxa significantly north of their modern ranges allow the reconstruction of warmer climatic conditions during LIG. Presumably, on Oyogos Yar, the mean temperature of the warmest month (MTWA) was at least ~4.5°C higher than today, which is supported by independent proxy-based - temperature reconstructions such as plant macro-fossils, pollen, and chironomids (Kienast et al., 2011) as well as by climate modeling simulations (Schirrmeister et al., submitted).
    Repository Name: EPIC Alfred Wegener Institut
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    Paleoclimate data assimilation with CLIMBER-X: An ensemble Kalman filter for the last deglaciation (2024)
    Public Library of Science (PLoS)
    In:  EPIC3PLOS ONE, Public Library of Science (PLoS), 19(4), pp. e0300138-e0300138, ISSN: 1932-6203
    Details
    Publication Date: 2024-04-26
    Description: Using the climate model CLIMBER-X, we present an efficient method for assimilating the temporal evolution of surface temperatures for the last deglaciation covering the period 22000 to 6500 years before the present. The data assimilation methodology combines the data and the underlying dynamical principles governing the climate system to provide a state estimate of the system, which is better than that which could be obtained using just the data or the model alone. In applying an ensemble Kalman filter approach, we make use of the advances in the parallel data assimilation framework (PDAF), which provides parallel data assimilation functionality with a relatively small increase in computation time. We find that the data assimilation solution depends strongly on the background evolution of the decaying ice sheets rather than the assimilated temperatures. Two different ice sheet reconstructions result in a different deglacial meltwater history, affecting the large-scale ocean circulation and, consequently, the surface temperature. We find that the influence of data assimilation is more pronounced on regional scales than on the global mean. In particular, data assimilation has a stronger effect during millennial warming and cooling phases, such as the Bølling-Allerød and Younger Dryas, especially at high latitudes with heterogeneous temperature patterns. Our approach is a step toward a comprehensive paleo-reanalysis on multi-millennial time scales, including incorporating available paleoclimate data and accounting for their uncertainties in representing regional climates.
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    Shifts in dominance of benthic communities along a gradient of water temperature and turbidity in tropical coastal ecosystems (2024)
    In:  PeerJ vol. 12 no. e17132
    Details
    Publication Date: 2024-04-26
    Description: Tropical coastal benthic communities will change in species composition and relative dominance due to global (e.g., increasing water temperature) and local (e.g., increasing terrestrial influence due to land-based activity) stressors. This study aimed to gain insight into possible trajectories of coastal benthic assemblages in Raja Ampat, Indonesia, by studying coral reefs at varying distances from human activities and marine lakes with high turbidity in three temperature categories (〈31 °C, 31–32 °C, and 〉32 °C). The benthic community diversity and relative coverage of major benthic groups were quantified via replicate photo transects. The composition of benthic assemblages varied significantly among the reef and marine lake habitats. The marine lakes 〈31 °C contained hard coral, crustose coralline algae (CCA), and turf algae with coverages similar to those found in the coral reefs (17.4–18.8% hard coral, 3.5–26.3% CCA, and 15–15.5% turf algae, respectively), while the higher temperature marine lakes (31–32 °C and 〉32 °C) did not harbor hard coral or CCA. Benthic composition in the reefs was significantly influenced by geographic distance among sites but not by human activity or depth. Benthic composition in the marine lakes appeared to be structured by temperature, salinity, and degree of connection to the adjacent sea. Our results suggest that beyond a certain temperature (〉31 °C), benthic communities shift away from coral dominance, but new outcomes of assemblages can be highly distinct, with a possible varied dominance of macroalgae, benthic cyanobacterial mats, or filter feeders such as bivalves and tubeworms. This study illustrates the possible use of marine lake model systems to gain insight into shifts in the benthic community structure of tropical coastal ecosystems if hard corals are no longer dominant.
    Keywords: Benthic cover ; Biodiversity ; Coral reef ; Marine lake ; Anthropogenic pressures ; Raja ; Ampat (Indonesia)
    Repository Name: National Museum of Natural History, Netherlands
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    Prokaryotic communities of the French Polynesian sponge Dactylospongia metachromia display a site-specific and stable diversity during an aquaculture trial (2024)
    In:  Antonie van Leeuwenhoek vol. 117 no. 1
    Details
    Publication Date: 2024-04-26
    Description: Dynamics of microbiomes through time are fundamental regarding survival and resilience of their hosts when facing environmental alterations. As for marine species with commercial applications, such as marine sponges, assessing the temporal change of prokaryotic communities allows us to better consider the adaptation of sponges to aquaculture designs. The present study aims to investigate the factors shaping the microbiome of the sponge Dactylospongia metachromia, in a context of aquaculture development in French Polynesia, Rangiroa, Tuamotu archipelago. A temporal approach targeting explants collected during farming trials revealed a relative high stability of the prokaryotic diversity, meanwhile a complementary biogeographical study confrmed a spatial specifcity amongst samples at diferent longitudinal scales. Results from this additional spatial analysis confrmed that diferences in prokaryotic communities might frst be explained by environmental changes (mainly temperature and salinity), while no signifcant efect of the host phylogeny was observed. The core community of D. metachromia is thus characterized by a high spatiotemporal constancy, which is a good prospect for the sustainable exploitation of this species towards drug development. Indeed, a microbiome stability across locations and throughout the farming process, as evidenced by our results, should go against a negative infuence of sponge translocation during in situ aquaculture.
    Keywords: Holobiont ; Marine sponges ; Microbiome ; Farming trials ; Biogeography ; French Polynesia
    Repository Name: National Museum of Natural History, Netherlands
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  • 97
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    Fungal Planet description sheets: 1112–1181 (2020)
    Naturalis Biodiversity Center
    In:  Persoonia - Molecular Phylogeny and Evolution of Fungi vol. 45, pp. 251-409
    Details
    Publication Date: 2024-04-26
    Description: Novel species of fungi described in this study include those from various countries as follows: Australia, Austroboletus asper on soil, Cylindromonium alloxyli on leaves of Alloxylon pinnatum, Davidhawksworthia quintiniae on leaves of Quintinia sieberi, Exophiala prostantherae on leaves of Prostanthera sp., Lactifluus lactiglaucus on soil, Linteromyces quintiniae (incl. Linteromyces gen. nov.) on leaves of Quintinia sieberi, Lophotrichus medusoides from stem tissue of Citrus garrawayi, Mycena pulchra on soil, Neocalonectria tristaniopsidis (incl. Neocalonectria gen. nov.) and Xyladictyochaeta tristaniopsidis on leaves of Tristaniopsis collina, Parasarocladium tasmanniae on leaves of Tasmannia insipida, Phytophthora aquae-cooljarloo from pond water, Serendipita whamiae as endophyte from roots of Eriochilus cucullatus, Veloboletus limbatus (incl. Veloboletus gen. nov.) on soil. Austria, Cortinarius glaucoelotus on soil. Bulgaria, Suhomyces rilaensis from the gut of Bolitophagus interruptus found on a Polyporus sp. Canada, Cantharellus betularum among leaf litter of Betula, Penicillium saanichii from house dust. Chile, Circinella lampensis on soil, Exophiala embothrii from rhizosphere of Embothrium coccineum. China, Colletotrichum cycadis on leaves of Cycas revoluta. Croatia, Phialocephala melitaea on fallen branch of Pinus halepensis. Czech Republic, Geoglossum jirinae on soil, Pyrenochaetopsis rajhradensis from dead wood of Buxus sempervirens. Dominican Republic, Amanita domingensis on litter of deciduous wood, Melanoleuca dominicana on forest litter. France, Crinipellis nigrolamellata (Martinique) on leaves of Pisonia fragrans, Talaromyces pulveris from bore dust of Xestobium rufovillosum infesting floorboards. French Guiana, Hypoxylon hepaticolor on dead corticated branch. Great Britain, Inocybe ionolepis on soil. India, Cortinarius indopurpurascens among leaf litter of Quercus leucotrichophora. Iran, Pseudopyricularia javanii on infected leaves of Cyperus sp., Xenomonodictys iranica (incl. Xenomonodictys gen. nov.) on wood of Fagus orientalis. Italy, Penicillium vallebormidaense from compost. Namibia, Alternaria mirabibensis on plant litter, Curvularia moringae and Moringomyces phantasmae (incl. Moringomyces gen. nov.) on leaves and flowers of Moringa ovalifolia, Gobabebomyces vachelliae (incl. Gobabebomyces gen. nov.) on leaves of Vachellia erioloba, Preussia procaviae on dung of Procavia capensis. Pakistan, Russula shawarensis from soil on forest floor. Russia, Cyberlindnera dauci from Daucus carota. South Africa, Acremonium behniae on leaves of Behnia reticulata, Dothiora aloidendri and Hantamomyces aloidendri (incl. Hantamomyces gen. nov.) on leaves of Aloidendron dichotomum, Endoconidioma euphorbiae on leaves of Euphorbia mauritanica, Eucasphaeria proteae on leaves of Protea neriifolia, Exophiala mali from inner fruit tissue of Malus sp., Graminopassalora geissorhizae on leaves of Geissorhiza splendidissima, Neocamarosporium leipoldtiae on leaves of Leipoldtia schultzii, Neocladosporium osteospermi on leaf spots of Osteospermum moniliferum, Neometulocladosporiella seifertii on leaves of Combretum caffrum, Paramyrothecium pituitipietianum on stems of Grielum humifusum, Phytopythium paucipapillatum from roots of Vitis sp., Stemphylium carpobroti and Verrucocladosporium carpobroti on leaves of Carpobrotus quadrifolius, Suttonomyces cephalophylli on leaves of Cephalophyllum pilansii. Sweden, Coprinopsis rubra on cow dung, Elaphomyces nemoreus from deciduous woodlands. Spain, Polyscytalum pini-canariensis on needles of Pinus canariensis, Pseudosubramaniomyces septatus from stream sediment, Tuber lusitanicum on soil under Quercus suber. Thailand, Tolypocladium flavonigrum on Elaphomyces sp. USA, Chaetothyrina spondiadis on fruits of Spondias mombin, Gymnascella minnisii from bat guano, Juncomyces patwiniorum on culms of Juncus effusus, Moelleriella puertoricoensis on scale insect, Neodothiora populina (incl. Neodothiora gen. nov.) on stem cankers of Populus tremuloides, Pseudogymnoascus palmeri from cave sediment. Vietnam, Cyphellophora vietnamensis on leaf litter, Tylopilus subotsuensis on soil in montane evergreen broadleaf forest. Morphological and culture characteristics are supported by DNA barcodes.
    Keywords: Ecology ; Evolution ; Behavior and Systematics ; ITS nrDNA barcodes ; LSU ; new taxa ; systematics
    Repository Name: National Museum of Natural History, Netherlands
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  • 98
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    Unknown
    Enhancements of geomechanical models for potential siting areas in Switzerland (2024)
    In:  Abstracts
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    Publication Date: 2024-04-26
    Language: English
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  • 99
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    Unknown
    Urban landslides triggered under similar rainfall conditions in cities globally (2024)
    In:  Abstracts
    Details
    Publication Date: 2024-04-26
    Language: English
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  • 100
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    Clumped and in situ carbon and oxygen isotopes of calcite as tracers for oxidation of hydrocarbons in deep siliciclastic strata (2024)
    In:  Geological Society of America Bulletin
    Details
    Publication Date: 2024-04-26
    Description: The oxidation of hydrocarbons, including methane, is part of interrelated hydrogeochemical reactions affecting the carbon budget in Earth’s crust. To investigate these processes in deep siliciclastic strata, we analyzed core samples from Lower Triassic red beds in the Mahu Sag (Junggar Basin, northwest China) by coupling petrological observations with high-resolution in situ secondary ion mass spectroscopy stable carbon and oxygen isotope analyses and clumped isotopes (Δ47) of authigenic calcite. The strata contain variable oil and gas content as well as abundant high-valence Fe and/or Mn oxides. Three sequential generations of cement occur, which are characterized as (1) non-luminescent, early diagenetic calcite (MnO 〈0.3%, δ13CVPDB [Vienna Peedee belemnite] = −5.6‰ to −4.1‰); (2) bright-orange luminescent late-stage I calcite (0.75%−5.23% MnO, δ13C = −51.4‰ to −25.8‰); and (3) dull-orange late-stage II calcite (4.10%−12.93% MnO, δ13C = −91.4‰ to −30.9‰). Clumped isotopic thermometry reveals that the calcite precipitation temperature increases successively from 〈40 °C, to 81−107 °C, to finally 107−132 °C, corresponding to three precipitation time periods: before the Late Triassic, from the Early Jurassic to the Early Cretaceous, and from the Early Cretaceous to the present, respectively. δ13C values of −55.7‰ to −25.8‰ indicate that late-stage I calcite is the final product of oxidation of both methane and C2+ hydrocarbons, whereas δ13C values as low as −91‰ indicate that late-stage II calcite is mainly derived from the thermochemical oxidation of methane (δ13C = −46.8‰ to −39.3‰) induced by high-valence Mn and/or Fe oxides. For late-stage I calcite, hydrocarbon oxidation was most likely promoted by high temperatures, although microbial oxidation cannot be completely ruled out. The higher precipitation temperature of late-stage II calcite demonstrates that the oxidation of methane requires higher activation energies than oxidation of C2+ hydrocarbons. We provide reliable geochemical evidence for thermally induced sequential oxidation of hydrocarbons within deep siliciclastic strata.
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