TY - JOUR A1 - Radosavljevic, Boris A1 - Lantuit, Hugues A1 - Knoblauch, Christian A1 - Couture, Nicole A1 - Herzschuh, Ulrike A1 - Fritz, Michael T1 - Arctic nearshore sediment dynamics - an example from Herschel Island - Qikiqtaruk, Canada JF - Journal of marine science and engineering N2 - Increasing arctic coastal erosion rates imply a greater release of sediments and organic matter into the coastal zone. With 213 sediment samples taken around Herschel Island-Qikiqtaruk, Canadian Beaufort Sea, we aimed to gain new insights on sediment dynamics and geochemical properties of a shallow arctic nearshore zone. Spatial characteristics of nearshore sediment texture (moderately to poorly sorted silt) are dictated by hydrodynamic processes, but ice-related processes also play a role. We determined organic matter (OM) distribution and inferred the origin and quality of organic carbon by C/N ratios and stable carbon isotopes delta C-13. The carbon content was higher offshore and in sheltered areas (mean: 1.0 wt.%., S.D.: 0.9) and the C/N ratios also showed a similar spatial pattern (mean: 11.1, S.D.: 3.1), while the delta C-13 (mean: -26.4 parts per thousand VPDB, S.D.: 0.4) distribution was more complex. We compared the geochemical parameters of our study with terrestrial and marine samples from other studies using a bootstrap approach. Sediments of the current study contained 6.5 times and 1.8 times less total organic carbon than undisturbed and disturbed terrestrial sediments, respectively. Therefore, degradation of OM and separation of carbon pools take place on land and continue in the nearshore zone, where OM is leached, mineralized, or transported beyond the study area. KW - permafrost KW - Arctic Ocean KW - stable carbon isotopes KW - nitrogen KW - sediment KW - chemistry KW - sediment dynamics KW - Beaufort Sea KW - grain size Y1 - 2022 U6 - https://doi.org/10.3390/jmse10111589 SN - 2077-1312 VL - 10 IS - 11 PB - MDPI CY - Basel ER - TY - JOUR A1 - Francke, Till A1 - Baroni, Gabriele A1 - Brosinsky, Arlena A1 - Foerster, Saskia A1 - Lopez-Tarazon, José Andrés A1 - Sommerer, Erik A1 - Bronstert, Axel T1 - What Did Really Improve Our Mesoscale Hydrological Model? BT - a Multidimensional Analysis Based on Real Observations JF - Water resources research N2 - Modelers can improve a model by addressing the causes for the model errors (data errors and structural errors). This leads to implementing model enhancements (MEs), for example, meteorological data based on more monitoring stations, improved calibration data, and/or modifications in process formulations. However, deciding on which MEs to implement remains a matter of expert knowledge. After implementing multiple MEs, any improvement in model performance is not easily attributed, especially when considering different objectives or aspects of this improvement (e.g., better dynamics vs. reduced bias). We present an approach for comparing the effect of multiple MEs based on real observations and considering multiple objectives (MMEMO). A stepwise selection approach and structured plots help to address the multidimensionality of the problem. Tailored analyses allow a differentiated view on the effect of MEs and their interactions. MMEMO is applied to a case study employing the mesoscale hydro-sedimentological model WASA-SED for the Mediterranean-mountainous Isabena catchment, northeast Spain. The investigated seven MEs show diverse effects: some MEs (e.g., rainfall data) cause improvements for most objectives, while other MEs (e.g., land use data) only affect a few objectives or even decrease model performance. Interaction of MEs was observed for roughly half of the MEs, confirming the need to address them in the analysis. Calibration and increasing the temporal resolution showed by far stronger impact than any of the other MEs. The proposed framework can be adopted in other studies to analyze the effect of MEs and, thus, facilitate the identification and implementation of the most promising MEs for comparable cases. KW - modeling KW - sensitivity analyses KW - model enhancement KW - sediment Y1 - 2018 U6 - https://doi.org/10.1029/2018WR022813 SN - 0043-1397 SN - 1944-7973 VL - 54 IS - 11 SP - 8594 EP - 8612 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Dommain, René A1 - Andama, Morgan A1 - McDonough, Molly M. A1 - Prado, Natalia A. A1 - Goldhammer, Tobias A1 - Potts, Richard A1 - Maldonado, Jesús E. A1 - Nkurunungi, John Bosco A1 - Campana, Michael G. T1 - The Challenges of Reconstructing Tropical Biodiversity With Sedimentary Ancient DNA BT - A 2200-Year-Long Metagenomic Record From Bwindi Impenetrable Forest, Uganda JF - Frontiers in Ecology and Evolution N2 - Sedimentary ancient DNA has been proposed as a key methodology for reconstructing biodiversity over time. Yet, despite the concentration of Earth’s biodiversity in the tropics, this method has rarely been applied in this region. Moreover, the taphonomy of sedimentary DNA, especially in tropical environments, is poorly understood. This study elucidates challenges and opportunities of sedimentary ancient DNA approaches for reconstructing tropical biodiversity. We present shotgun-sequenced metagenomic profiles and DNA degradation patterns from multiple sediment cores from Mubwindi Swamp, located in Bwindi Impenetrable Forest (Uganda), one of the most diverse forests in Africa. We describe the taxonomic composition of the sediments covering the past 2200 years and compare the sedimentary DNA data with a comprehensive set of environmental and sedimentological parameters to unravel the conditions of DNA degradation. Consistent with the preservation of authentic ancient DNA in tropical swamp sediments, DNA concentration and mean fragment length declined exponentially with age and depth, while terminal deamination increased with age. DNA preservation patterns cannot be explained by any environmental parameter alone, but age seems to be the primary driver of DNA degradation in the swamp. Besides degradation, the presence of living microbial communities in the sediment also affects DNA quantity. Critically, 92.3% of our metagenomic data of a total 81.8 million unique, merged reads cannot be taxonomically identified due to the absence of genomic references in public databases. Of the remaining 7.7%, most of the data (93.0%) derive from Bacteria and Archaea, whereas only 0–5.8% are from Metazoa and 0–6.9% from Viridiplantae, in part due to unbalanced taxa representation in the reference data. The plant DNA record at ordinal level agrees well with local pollen data but resolves less diversity. Our animal DNA record reveals the presence of 41 native taxa (16 orders) including Afrotheria, Carnivora, and Ruminantia at Bwindi during the past 2200 years. Overall, we observe no decline in taxonomic richness with increasing age suggesting that several-thousand-year-old information on past biodiversity can be retrieved from tropical sediments. However, comprehensive genomic surveys of tropical biota need prioritization for sedimentary DNA to be a viable methodology for future tropical biodiversity studies. KW - sedimentary ancient DNA KW - tropical biodiversity KW - DNA preservation KW - sediment KW - tropical swamp KW - shotgun sequencing KW - metagenomic analysis Y1 - 2019 U6 - https://doi.org/10.3389/fevo.2020.00218 SN - 2296-701X VL - 8 PB - Frontiers Media CY - Lausanne ER - TY - GEN A1 - Dommain, René A1 - Andama, Morgan A1 - McDonough, Molly M. A1 - Prado, Natalia A. A1 - Goldhammer, Tobias A1 - Potts, Richard A1 - Maldonado, Jesús E. A1 - Nkurunungi, John Bosco A1 - Campana, Michael G. T1 - The Challenges of Reconstructing Tropical Biodiversity With Sedimentary Ancient DNA BT - A 2200-Year-Long Metagenomic Record From Bwindi Impenetrable Forest, Uganda T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Sedimentary ancient DNA has been proposed as a key methodology for reconstructing biodiversity over time. Yet, despite the concentration of Earth’s biodiversity in the tropics, this method has rarely been applied in this region. Moreover, the taphonomy of sedimentary DNA, especially in tropical environments, is poorly understood. This study elucidates challenges and opportunities of sedimentary ancient DNA approaches for reconstructing tropical biodiversity. We present shotgun-sequenced metagenomic profiles and DNA degradation patterns from multiple sediment cores from Mubwindi Swamp, located in Bwindi Impenetrable Forest (Uganda), one of the most diverse forests in Africa. We describe the taxonomic composition of the sediments covering the past 2200 years and compare the sedimentary DNA data with a comprehensive set of environmental and sedimentological parameters to unravel the conditions of DNA degradation. Consistent with the preservation of authentic ancient DNA in tropical swamp sediments, DNA concentration and mean fragment length declined exponentially with age and depth, while terminal deamination increased with age. DNA preservation patterns cannot be explained by any environmental parameter alone, but age seems to be the primary driver of DNA degradation in the swamp. Besides degradation, the presence of living microbial communities in the sediment also affects DNA quantity. Critically, 92.3% of our metagenomic data of a total 81.8 million unique, merged reads cannot be taxonomically identified due to the absence of genomic references in public databases. Of the remaining 7.7%, most of the data (93.0%) derive from Bacteria and Archaea, whereas only 0–5.8% are from Metazoa and 0–6.9% from Viridiplantae, in part due to unbalanced taxa representation in the reference data. The plant DNA record at ordinal level agrees well with local pollen data but resolves less diversity. Our animal DNA record reveals the presence of 41 native taxa (16 orders) including Afrotheria, Carnivora, and Ruminantia at Bwindi during the past 2200 years. Overall, we observe no decline in taxonomic richness with increasing age suggesting that several-thousand-year-old information on past biodiversity can be retrieved from tropical sediments. However, comprehensive genomic surveys of tropical biota need prioritization for sedimentary DNA to be a viable methodology for future tropical biodiversity studies. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 970 KW - sedimentary ancient DNA KW - tropical biodiversity KW - DNA preservation KW - sediment KW - tropical swamp KW - shotgun sequencing KW - metagenomic analysis Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-474305 SN - 1866-8372 IS - 970 ER -