Artykuły naukowe (WNGiG)

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    Explanation of the influence of geomorphometric variables on the landform classification based on selected areas in Poland
    (Nature Publishing Group, 2024-03-05) Dyba, Krzysztof
    In recent years, automatic image classification methods have significantly progressed, notably black box algorithms such as machine learning and deep learning. Unfortunately, such efforts only focused on improving performance, rather than attempting to explain and interpret how classification models actually operate. This article compares three state-of-the-art algorithms incorporating random forests, gradient boosting and convolutional neural networks for geomorphological mapping. It also attempts to explain how the most effective classifier makes decisions by evaluating which of the geomorphometric variables are most important for automatic mapping and how they affect the classification results using one of the explainable artificial intelligence techniques, namely accumulated local effects (ALE). This method allows us to understand the relationship between predictors and the model’s outcome. For these purposes, eight sheets of the digital geomorphological map of Poland on the scale of 1:100,000 were used as the reference material. The classification results were validated using the holdout method and cross-validation for individual sheets representing different morphogenetic zones. The terrain elevation entropy, absolute elevation, aggregated median elevation and standard deviation of elevation had the greatest impact on the classification results among the 15 geomorphometric variables considered. The ALE analysis was conducted for the XGBoost classifier, which achieved the highest accuracy of 92.8%, ahead of Random Forests at 84% and LightGBM at 73.7% and U-Net at 59.8%. We conclude that automatic classification can support geomorphological mapping only if the geomorphological characteristics in the predicted area are similar to those in the training dataset. The ALE plots allow us to analyze the relationship between geomorphometric variables and landform membership, which helps clarify their role in the classification process.
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    Jaskinia Lodowa w Ciemniaku (Ice Cave in Ciemniak), Western Tatra, Poland - over a century-long investigations of climate warming-caused degradation of subterranean ice mass
    (Institute of Geography and Spatial Organization Polish Academy of Sciences, 2023-12) Barabach, Jan; Szczuciński, Witold; Kicińska, Ditta; Palińska, Zuzanna; Rachlewicz, Grzegorz
    Jaskinia Lodowa w Ciemniaku (Ice Cave in Ciemniak), in the Tatra Mountains (Tatry), is believed to host the largest subterranean ice mass in Poland. It has been known for over a century, however, the onset of its scientific investigations dates back to 1922, when Tadeusz and Stefan Zwoliński mapped it. Since then, it has become one of the best-known caves in Poland. It was described in over a hundred scientific and popular science papers. They include findings of international importance, e.g. works related to radioisotopes ,ice-mass balance and age. However, some of the questions asked a century ago are still partly unanswered. One may wonder if they will be delivered before climate warming causes the largest ‘cave glacier’ in Poland to disappear.
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    In front of the retreating ice-sheet: Fauna complex of Central Poland in MIS 3–2 (Krosinko site)
    (Elsevier, 2023) Pawłowska, Kamilla
    A new locality in Central Europe (Krosinko, Poland) yields a rich fossil material of great taxonomical variety. Its location in the Warsaw–Berlin ice-marginal valley, where it forms a 1-m horizon at a the depth of 6–8 m, is suited to a taphonomic analysis aimed at reconstructing the paleoevents and depositional history of the late Pleistocene (MIS 3–2). Our analysis revealed that the material accumulated as the result of high-energy fluvial transport. This transport disturbed the original bone associations, as indicated by the lack of articulation, low refitting, and bone surface modification. During water movement, the bones were polished, abraded, pitted, and fragmented. Prior to that, however, taphonomic signatures were left behind by predators, humans, and plant roots. This is the first time that unquestionable burning marks have been found on woolly rhino remains from Poland. The secondary context of the faunal assemblage was confirmed by neodymium isotope studies of the faunal fragments and sediment. Given the results of sedimentological analysis from previous studies, these sediments can be associated with a high-energy braided river. The remains were moved along with paleobotanical material and flints in a westerly direction; this is suggested by the direction of water flows in the valley and the river waters supplying it. The deposition occurred within a single geologic event around 26 ka BP, as indicated by the youngest radiocarbon date of the remains, or ca. 19 ka BP, considering the geochronological constraints for the local LGM ice margin position in central and eastern Poland ~22–18 ka, and the specified accumulation time of the sediments in which they were found. Secondary mineralization of manganese and iron on the bones was the final taphonomical process that impacted the remains. The combined taphonomic, palaeozoological, isotopic and geological results show for the first time for a Polish paleontological site how data integration improves interpretation and highlights the advantages of a multiproxy approach.
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    Refining the history of extreme coastal events in southern Newfoundland, NW Atlantic, with lake sediment archives
    (Elsevier, 2023-11) Pleskot, Krzysztof; Cwynar, Les C.; Kowalczyk, Cyprian; Kokociński, Mikołaj; Szczuciński, WItold
    Extreme events, including tsunamis, storm surges and hurricanes, affect the western North Atlantic coast, threatening communities and impacting ecosystems. Although these extreme coastal events (ECEs) are currently thoroughly monitored in the area, older ECEs are known only from short historical evidence. Therefore, establishing a reliable ECE history that extends more than several decades into the past requires data from geological records. This study aims to refine the existing record of ECEs on the southern Burin Peninsula (Newfoundland, Canada) that extends back to the mid-18th century by providing the first lake-sediment-based reconstruction of the event history of the Canadian province of Newfoundland and Labrador. We investigated short sediment cores collected from four shallow coastal lakes. The identification of ECEs relied mainly on lithostratigraphic evidence and peak detection of sand grain counts. Diatoms, dry bulk density, and loss-on-ignition were also analyzed. The age-depth models of the cores were based on 210Pb and 137Cs dating. The correlation of our records with major historical events confirmed that statistically significant sand count peaks, sand layers, and redeposited peat clasts are indicative of major ECEs. We found that the type and characteristics of ECE records depended mainly on the availability of sediment, distance from the seashore, and magnitude of the event. Although some of our ECE markers are associated with marine inundations, only slight diatom community changes were observed, contrary to what is commonly expected from the disturbance of brackish and freshwater ecosystems by major saltwater intrusions. Combined, our records indicate that at least eight ECEs occurred since the late 17th century, three of which might correlate with historically documented events, namely the 1755 CE Lisbon tsunami, the 1775 CE Great Independence Hurricane, and the 1929 CE Newfoundland tsunami. Although further investigations are required to better constrain the type and magnitude of particular ECEs, our study confirms the suitability of geological archives for improving hazard assessment in coastal regions.
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    Fossil organic carbon utilization in marine Arctic fjord sediments by subsurface micro-organisms
    (2023-07) Ruben, Manuel; Hefter, Jens; Schubotz, Florence; Geibert, Walter; Butzin, Martin; Gentz, Torben; Grotheer, Hendrik; Forwick, Matthias; Szczuciński, Witold; Mollenhauer, Gesine
    Rock-derived or petrogenic organic carbon has traditionally been regarded as being non-bioavailable and bypassing the active carbon cycle when eroded. However, it has become apparent that this organic carbon might not be so inert, especially in fjord systems where petrogenic organic carbon influxes can be high, making its degradation another potential source of greenhouse gas emissions. The extent to which subsurface micro-organisms use this organic carbon is not well constrained, despite its potential impacts on global carbon cycling. Here, we performed compound-specific radiocarbon analyses on intact polar lipid–fatty acids of live micro-organisms from marine sediments in Hornsund Fjord, Svalbard. By this means, we estimate that local bacterial communities utilize between 5 ± 2% and 55 ± 6% (average of 25 ± 16%) of petrogenic organic carbon for their biosynthesis, providing evidence for the important role of petrogenic organic carbon as a substrate after sediment redeposition. We hypothesize that the lack of sufficient recently synthesized organic carbon from primary production forces micro-organisms into utilization of petrogenic organic carbon as an alternative energy source. The input of petrogenic organic carbon to marine sediments and subsequent utilization by subsurface micro-organisms represents a natural source of fossil greenhouse gas emissions over geological timescales.
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    Late Holocene Vistula River floods recorded in grain size distributions and diatom assemblages of marine sediments of the Gulf of Gdańsk (Baltic Sea)
    (Elsevier, 2023-05-01) Szcześniak, Marta; Kokociński, Mikołaj; Jagodziński, Robert; Pleskot, Krzysztof; Zajączkowski, Marek; Szczuciński, Witold
    During the large flood of the Vistula River in 2010, the riverine brackish water surface plume extended up to 70 km into the Gulf of Gdańsk (Baltic Sea), leaving a thin layer of medium-grained sand deposits. It inspired a search for palaeoflood records in marine sediments. Thus, we aimed to identify the most useful flood indicators and apply them to reveal palaeoflood records in sediment cores from the Gulf of Gdańsk. The study is based on analyses of surface samples, collected during and one year after the 2010 flood, and two long sediment cores, which were subjected to high-resolution grain size, diatom, and geochemical analyses, while chronology was based on the combined AMS 14C, 210Pb and 137Cs dating. It was found that, in a water depth of less than 30 m, modern large flood deposits were not preserved after a year. Sediment cores retrieved from greater water depths (over 60 m) were composed of sandy mud, and most of the 1 cm thick sediment samples were characterized by unimodal grain size distribution. However, some of the samples were bimodal, with the additional mode in fine-grained fractions, which is interpreted to be the result of direct deposition from riverine flood surface water plume. The diatom assemblages revealed a moderate downcore variability, except for the intervals characterized by bimodal grain size distributions. They contained elevated amounts of benthic oligohalobous (freshwater) and decreased euhalobous and mesohalobous taxa, supporting the likely interpretation of these layers as deposited during river flood events. During the last c. 4 ka, a dozen major flood events were identified. However, their application to flood climate reconstruction is challenging because of relatively frequent and partly unknown changes in major river mouth positions in the past. We suggest that thin deposits of major floods left on the seafloor and subjected to further mixing maybe still recognized using a combination of high-resolution grain size distribution and diatom analyses supplemented by a good understanding of the depositional system history.
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    Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia
    (Copernicus Publications, 2023-02-02) Majewski, Wojciech; Szczuciński, Witold; Gooday, Andrew J.
    Sub-Antarctic fjords are among the environments most affected by the recent climate change. In our dynamically changing world, it is essential to monitor changes in these vulnerable settings. Here, we present a baseline study of “living” (rose-bengal-stained) benthic foraminifera from fjords of South Georgia, including fjords with and without tidewater glaciers. Their distribution is analyzed in the light of new fjord water and sediment property data, including grain size and sorting, total organic carbon, total sulfur, and δ13C of bulk organic matter. Four well-defined foraminiferal assemblages are recognized. Miliammina earlandi dominates in the most restricted, near-shore and glacier-proximal habitats, Cassidulinoides aff. parkerianus in mid-fjord areas, and Globocassidulina aff. rossensis and an assemblage dominated by Ammobaculites rostratus, Reophax subfusiformis, and Astrononion echolsi are in the outer parts of the fjords. Miliammina earlandi can tolerate strong glacial influence, including high sedimentation rates in fjord heads and sediment anoxia, as inferred from sediment color and total organic carbon  sulfur ratios. This versatile species thrives both in the food-poor inner reaches of fjords that receive mainly refractory petrogenic organic matter from glacial meltwater and in shallow-water coves, where it benefits from an abundant supply of fresh, terrestrial, and marine organic matter. A smooth-walled variant of C. aff. parkerianus, apparently endemic to South Georgia, is the calcareous rotaliid best adapted to inner-fjord conditions characterized by moderate glacial influence and sedimentation rates and showing no preference for particular sedimentary redox conditions. The outer parts of fjords with clear, well-oxygenated bottom water are inhabited by G. aff. rossensis. Ammobaculites rostratus, R. subfusiformis, and A. echolsi dominate in the deepest-water settings, with water salinities ≥ 33.9 PSU and temperatures 0.2–1.4 ∘C, characteristic of winter water and Upper Circumpolar Deep Water. The inner- and mid-fjord foraminiferal assemblages seem specific to South Georgia, although with continued warming and deglaciation, they may become more widespread in the Southern Ocean.
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    Small impact cratering processes produce distinctive charcoal assemblages
    (2022-11) Losiak, Anna; Belcher, C. M.; Plado, J.; Jõeleht, A.; Herd, C. D. K.; Kofman, R. S.; Szokaluk, Monika; Szczuciński, Witold; Muszyński, Andrzej; Wild, E. M.; Baker, S. J.
    The frequency of crater-producing asteroid impacts on Earth is not known. Of the predicted Holocene asteroid impact craters of <200 m diameter, only ~30% have been located. Until now there has been no way to distinguish them from “normal” terrestrial structures unless pieces of iron meteorites were found nearby. We show that the reflective properties of charcoal found in the proximal ejecta of small impact craters are distinct from those produced by wildfires. Impact-produced charcoals and wildfire charcoals must derive from different heating regimes. We suggest that charcoal with specific reflective properties may help to recognize the meteoritic origin of small craters.
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    Fires, vegetation, and human - The history of critical transitions during the last 1000 years in Northeastern Mongolia
    (2022-09) Słowiński, Michał; Obremska, Milena; Avirmed, Dashtseren; Woszczyk, Michał; Adiya, Saruulzaya; Łuców, Dominika; Mroczkowska, Agnieszka; Hałaś, Agnieszka; Szczuciński, Witold; Kruk, Andrzej; Lamentowicz, Mariusz; Stańczak, Joanna; Rudaya, Natalia
    Fires are natural phenomena that impact human behaviors, vegetation, and landscape functions. However, the long-term history of fire, especially in the permafrost marginal zone of Central Asia (Mongolia), is poorly understood. This paper presents the results of radiocarbon and short-lived radionuclides (210Pb and 137Cs) dating, pollen, geochemical, charcoal, and statistical analyses (Kohonen's artificial neural network) of sediment core obtained from Northern Mongolia (the Khentii Mountains region). Therefore, we present the first high-resolution fire history from Northern Mongolia covering the last 1000 years, based on a multiproxy analysis of peat archive data. The results revealed that most of the fires in the region were likely initiated by natural factors, which were probably related to heatwaves causing prolonged droughts. We have demonstrated the link between enhanced fires and “dzud”, a local climatic phenomenon. The number of livestock, which has been increasing for several decades, and the observed climatic changes are superimposed to cause “dzud”, a deadly combination of droughts and snowy winter, which affects fire intensity. We observed that the study area has a sensitive ecosystem that reacts quickly to climate change. In terms of changes in the vegetation, the reconstruction reflected climate variations during the last millennium, the degradation of permafrost and occurrence of fires. However, more sites with good chronologies are needed to thoroughly understand the spatial relationships between changing climate, permafrost degradation, and vegetation change, which ultimately affect the nomadic societies in the region of Central and Northern Mongolia.
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    Evaluation of Methods for Estimating Lake Surface Water Temperature Using Landsat 8
    (2022-08-08) Dyba, Krzysztof; Ermida, Sofia; Ptak, Mariusz; Piekarczyk, Jan; Sojka, Mariusz
    Changes in lake water temperature, observed with the greatest intensity during the last two decades, may significantly affect the functioning of these unique ecosystems. Currently, in situ studies in Poland are conducted only for 38 lakes using the single-point method. The aim of this study was to develop a method for remote sensing monitoring of lake water temperature in a spatio-temporal context based on Landsat 8 imagery. For this purpose, using data obtained for 28 lakes from the period 2013–2020, linear regression (LM) and random forest (RF) models were developed to estimate surface water temperature. In addition, analysis of Landsat Level-2 Surface Temperature Science Product (LST-L2) data provided by United States Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA) was performed. The remaining 10 lakes not previously used in the model development stage were used to validate model performance. The results showed that the most accurate estimation is possible using the RF method for which RMSE = 1.83 °C and R^2 = 0.89, while RMSE = 3.68 °C and R^2 = 0.8 for the LST-L2 method. We found that LST-L2 contains a systematic error in the coastal zone, which can be corrected and eventually improve the quality of estimation. The satellite-based method makes it possible to determine water temperature for all lakes in Poland at different times and to understand the influence of climatic factors affecting temperature at the regional scale. On the other hand, spatial presentation of thermics within individual lakes enables understanding the influence of local factors and morphometric conditions.
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    Toward geomorphometry of plains - Country-level unsupervised classification of low-relief areas (Poland)
    (2022) Dyba, Krzysztof; Jasiewicz, Jarosław
    Low-relief areas are not fully the main subject of geomorphometric analyses. The development of the automatic classification of landforms mainly focuses on landforms related to the fluvial morphogenetic cycle. Thus, the morphogenetic diversity of the plains is not reflected in the existing classification systems. The area of Poland where the low relief area exceeds 80 % of the country's territory and results in various morphogenetic processes was selected for the analysis. The purpose of the analysis was recognition of the differentiation of surface types. The first step includes selecting appropriate morphogenetic variables, the second unsupervised classification using the Gaussian Mixture Model, and the third one encompassing the interpretation, namely the labeling process. Twenty Land Surface Types were distinguished, five belonging to uplands, and the remaining 15 types of plains were divided into four subgroups: rolling plains, dissection plains, smooth plains, and near-flat plains. Compared with other classification systems, terrain forms, morphogenetic strides, and physiographic division. The comparison showed a strong correspondence between the morphogenesis of the area and the inventory of surface types, and the high consistency of the Land Surface Types patterns within physiographic units.
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    Controls on coastal flooding in the southern Baltic Sea revealed from the late Holocene sedimentary records
    (2022-06-11) Leszczyńska, Karolina; Stattegger, Karl; Moskalewicz, Damian; Jagodziński, Robert; Kokociński, Mikołaj; Niedzielski, Przemysław; Szczuciński, Witold
    Climate change and related sea-level rise pose significant threats to lowland coasts. However, the role of key controlling factors responsible for the frequency and landward extent of extreme storm surges is not yet fully understood. Here, we present a high-resolution sedimentary record of extreme storm surge flooding from the non-tidal southern Baltic Sea, spanning two periods: 3.6–2.9 ka BP and 0.7 ka BP until present. Sediments from coastal wetland, including sandy event layers, were analyzed by sedimentological (grain size, loss-on-ignition, micromorphology), geochronological (14C), geochemical (XRF), mineralogical (heavy minerals) and micropaleontological (diatoms) methods. The results show that both periods were characterized by high-frequency of storm surge flooding, in order of 1.3–4.2 events per century. These periods correlate with phases of enhanced storminess in northwest Europe and took place during both rising and fluctuating sea levels. The study shows that the frequency and landward extent of coastal inundation, largely depended on the development of natural barriers (e.g. beach ridges and aeolian foredunes). Thus, in the context of the future coastal storm-surge hazard, the protection of existing coastal barriers and their morphology is essential.
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    Reflectance spectroscopy and machine learning as a tool for the categorization of twin species based on the example of the Diachrysia genus
    (2022-02-17) Dyba, Krzysztof; Wąsala, Roman; Piekarczyk, Jan; Gabała, Elżbieta; Gawlak, Magdalena; Jasiewicz, Jarosław; Ratajkiewicz, Henryk
    In our work we used noninvasive point reflectance spectroscopy in the range from 400 to 2100 nm coupled with machine learning to study scales on the brown and golden iridescent areas on the dorsal side of the forewing of Diachrysia chrysitis and D. stenochrysis. We used our approach to distinguish between these species of moths. The basis for the study was a statistically significant collection of 95 specimens identified based on morphological feature and gathered during 23 years in Poland. The numerical part of an experiment included two independent discriminant analyses: stochastic and deterministic. The more sensitive stochastic approach achieved average compliance with the species identification made by entomologists at the level of 99–100%. It demonstrated high stability against the different configurations of training and validation sets, hence strong predictors of Diachrysia siblings distinctiveness. Both methods resulted in the same small set of relevant features, where minimal fully discriminating subsets of wavelengths were three for glass scales on the golden area and four for the brown. The differences between species in scales primarily concern their major components and ultrastructure. In melanin-absent glass scales, this is mainly chitin configuration, while in melanin-present brown scales, melanin reveals as an additional factor.
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    Lower Carboniferous solitary rugose corals from the Flett Formation of the Liard Basin, northwestern Canada vs. European and Asian Rugosa of the same geological age
    (Instytut Geologii UW, 2022) Chwieduk, Edward
    The paper focuses on the taxonomic description of the lower Carboniferous (uppermost Tournaisian to middle Viséan) solitary rugose corals from bedded limestone and shale units in the Flett Formation in the Jackfish Gap (eastern Liard Range), northwestern Canada. The corals described herein include 12 species representing the genera Ankhelasma Sando, 1961, Bradyphyllum Grabau, 1928, Caninophyllum Lewis, 1929, Cyathaxonia Michelin, 1847, Ekvasophyllum Parks, 1951, EnniskilleniaKabakovich in Soshkina et al., 1962, Vesiculophyllum Easton, 1944 and Zaphrentites Hudson, 1941. Two of these species are new Ankhelasma canadense sp. nov. and Ekvasophyllum variabilis sp. nov.) and 6 taxa are described in open nomenclature. The distribution and relative abundance of solitary Rugosa in Europe and the Liard Basin confirm the geographical proximity of those areas and the open marine communication between them during the early Carboniferous. It therefore represents an important contribution to the determination of the time of isolation of the western Laurussia shelf fauna from that of southeastern Laurussia, as well as the time of the possible emergence of species from southeastern Laurussia into the western aurussia seas. Of particular importance here are cosmopolitan taxa and the timing of their disappearance from the fossil record.
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    Coexistence of Lobelia dortmanna and Cladium mariscus, an ecological and paleobotanical study
    (2021) Milecka, Krystyna; Kowalewski, Grzegorz; Lewandowska, Agnieszka; Szczuciński, Witold; Goslar, Tomasz
    Lobelia dortmanna L. (Lobeliaceae family) is an indicator species that is predominantly found in oligotrophic and acidic lakes. They are mainly distributed in northwestern Europe. Their occurrence in Poland is highly threatened by the increasing grade of human activity and environmental eutrophication; however, new sites of Lobelia were discovered in the last few decades, for example, in Lake Krzywce Wielkie situated in Bory Tucholskie National Park (BTNP), Poland. The existence of Lobelia in this lake was unexpected because Cladium mariscus was also found in the lake. Cladium has different ecological demands and is regarded as a species typical of calcareous habitats where calcium is found in abundance in the substrate. To explain the coexistence of both species in Krzywce Wielkie, pollen analysis of organic sediments was performed for four short cores collected from the littoral zone of the lake and for one long deep-water core. Additionally, macrofossil analysis was done for all the short cores. Pollen analysis revealed the existence of Cladium from the early Holocene period up to the present time. Pollen and seeds of Lobelia were found to be present since the beginning of the 20th century. Development of L. dortmanna and Myriophyllum alterniflorum populations and a decrease in the number of aquatic macrophytes in the eutrophic water indicate oligotrophication of water. This process started following the construction of drainage canal and the consequent water level decrease. This situation can be attributed to the abandonment of the agricultural areas adjoining the lake, which causes a decrease in the inflow of nutrients into the lake. Development of pine forest and establishment of BTNP enabled the protection and conservation of the surrounding catchment areas, thus restricting the potential eutrophication of the habitats.
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    Preliminary evidence of an endangered species benefiting from moderate climate warming: A palaeolimnological study of the charophyte Lychnothamnus barbatus
    (John Wiley & Sons Ltd., 2021) Brzozowski, Michał; Kowalewski, Grzegorz; Szczuciński, Witold; Kaczmarek, Lech; Pełechaty, Mariusz
    1. In a time of rapid environmental changes, identification of the effects of climate warming on charophytes (Characeae, Charophyta) will enable the optimization of conservation measures, especially for extremely rare species. Lychnothamnus barbatus is one of the rarest charophytes worldwide, which has decreased in the number of occupied sites over the last century. However, the recolonization of former sites has been observed in recent years (e.g. Lake Ku znickie, Poland). The study aimed to analyse the effects of climatic changes and human pressure on the L. barbatus population. 2. Three 30 cm sediment cores were collected from minimum, average, and maximum depths of L. barbatus occurrence to determine the past vegetation composition. Sediment cores were dated using the radioisotopes lead-210, caesium-137, and carbon-14. A spatial analysis of the lake catchment changes during the last 120 years was also conducted. 3. The study demonstrated L. barbatus presence in Lake Kuźnickie at the beginning of the 16th century. However, a sharp increase in the proportion of this species in the vegetation community occurred in the 19th century and during climate warming at the end of the Little Ice Age. Factors that significantly influenced the present occurrence of the L. barbatus population included improvement in water quality and the oospore bank deposited in the bottom sediments. 4. This study is the first palaeoreconstruction in a modern lake dominated by L. barbatus. Based on the history of L. barbatus in Lake Kuźnickie after the end of the Little Ice Age, the positive effect of climate warming on the contemporary recovery of this charophyte is postulated. 5. The reaction of L. barbatus to climate warming appears to differ from commonly accepted scenarios for aquatic macrophytes because its recovery in the past and at present coincided with increases in air temperature. This research indicated the appropriate management and conservation practices for lakes with L. barbatus populations.
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    Cryoconite – From minerals and organic matter to bioengineered sediments on glacier's surfaces
    (Elsevier, 2022) Rozwalak, Piotr; Podkowa, Paweł; Buda, Jakub; Niedzielski, Przemysław; Kawecki, Szymon; Ambrosini, Roberto; Azzoni, Roberto S.; Baccolo, Giovanni; Ceballos, Jorge L.; Cook, Joseph; Di Mauro, Biagio; Ficetola, Gentile Francesco; Franzetti, Andrea; Ignatiuk, Dariusz; Klimaszyk, Piotr; Łokas, Edyta; Ono, Masato; Parnikoza, Ivan; Pietryka, Mirosława; Pittino, Francesca; Poniecka, Ewa; Porazinska, Dorota L.; Richter, Dorota; Schmidt, Steven K.; Sommers, Pacifica; Souza-Kasprzyk, Juliana; Stibal, Marek; Szczuciński, Witold; Uetake, Jun; Wejnerowski, Łukasz; Yde, Jacob C.; Takeuchi, Nozomu; Zawierucha, Krzysztof
    Cryoconite is a mixture of mineral and organic material covering glacial ice, playing important roles in biogeochemical cycles and lowering the albedo of a glacier surface. Understanding the differences in structure of cryoconite across the globe can be important in recognizing past and future changes in supraglacial environments and ice-organisms-minerals interactions. Despite the worldwide distribution and over a century of studies, the basic characteristics of cryoconite, including its forms and geochemistry, remain poorly studied. The major purpose of our study is the presentation and description of morphological diversity, chemical and photoautotrophs composition, and organic matter content of cryoconite sampled from 33 polar and mountain glaciers around the globe. Observations revealed that cryoconite is represented by various morphologies including loose and granular forms. Granular cryoconite includes smooth, rounded, or irregularly shaped forms; with some having their surfaces covered by cyanobacteria filaments. The occurrence of granules increased with the organic matter content in cryoconite. Moreover, a major driver of cryoconite colouring was the concentration of organic matter and its interplay with minerals. The structure of cyanobacteria and algae communities in cryoconite differs between glaciers, but representatives of cyanobacteria families Pseudanabaenaceae and Phormidiaceae, and algae familiesMesotaeniaceae and Ulotrichaceae were the most common. The most of detected cyanobacterial taxa are known to produce polymeric substances (EPS) that may cement granules. Organic matter content in cryoconite varied between glaciers, ranging from 1% to 38%. The geochemistry of all the investigated samples reflected local sediment sources, except of highly concentrated Pb and Hg in cryoconite collected from Europeanglaciers near indus-rialized regions, corroborating cryoconite as element-specific collector and potential environmental indicator of anthropogenic activity. Our work supports a notion that cryoconite may be more than just simple sediment and instead exhibits complex structure with relevance for biodiversity and the functioning of glacial ecosystems.
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    Multiproxy paleoceanographic study from the western Barents Sea reveals dramatic Younger Dryas onset followed by oscillatory warming trend
    (Springer Nature, 2020-09) Łącka, Magdalena; Michalska, Danuta; Pawłowska, Joanna; Szymańska, Natalia; Szczuciński, Witold; Forwick, Matthias; Zajączkowski, Marek
    The Younger Dryas (YD) is recognized as a cool period that began and ended abruptly during a time of general warming at the end of the last glacial. New multi-proxy data from a sediment gravity core from Storfjordrenna (western Barents Sea, 253 m water depth) reveals that the onset of the YD occurred as a single short-lived dramatic environment deterioration, whereas the subsequent warming was oscillatory. The water masses in the western Barents Sea were likely strongly stratified at the onset of the YD, possibly due to runoff of meltwater combined with perennial sea-ice cover, the latter may last up to several decades without any brake-up. Consequently, anoxic conditions prevailed at the bottom of Storfjordrenna, leading to a sharp reduction of benthic biota and the appearance of vivianite microconcretions which formation is favoured by reducing conditions. While the anoxic conditions in Storfjordrenna were transient, the unfavorable conditions for benthic foraminifera lasted for c. 1300 years. We suggest that the Pre-Boreal Oscillation, just after the onset of the Holocene, may have been a continuation of the oscillatory warming trend during the YD.
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    Temperature increase altered Daphnia community structure in artificially heated lakes: a potential scenario for a warmer future
    (Springer Nature, 2020-08) Dziuba, Marcin; Herdegen‑Radwan, Magdalena; Pluta, Estera; Wejnerowski, Łukasz; Szczuciński, Witold; Cerbin, Sławek
    Under conditions of global warming, organisms are expected to track their thermal preferences, invading new habitats at higher latitudes and altitudes and altering the structure of local communities. To fend off potential invaders, indigenous communities/populations will have to rapidly adapt to the increase in temperature. In this study, we tested if decades of artificial water heating changed the structure of communities and populations of the Daphnia longispina species complex. We compared the species composition of contemporary Daphnia communities inhabiting five lakes heated by power plants and four non-heated control lakes. The heated lakes are ca. 3–4 °C warmer, as all lakes are expected to be by 2100 according to climate change forecasts. We also genotyped subfossil resting eggs to describe past shifts in Daphnia community structure that were induced by lake heating. Both approaches revealed a rapid replacement of indigenous D. longispina and D. cucullata by invader D. galeata immediately after the onset of heating, followed by a gradual recovery of the D. cucullata population. Our findings clearly indicate that, in response to global warming, community restructuring may occur faster than evolutionary adaptation. The eventual recolonisation by D. cucullata indicates that adaptation to novel conditions can be time-lagged, and suggests that the long-term consequences of ecosystem disturbance may differ from short-term observations.
Uniwersytet im. Adama Mickiewicza w Poznaniu
Biblioteka Uniwersytetu im. Adama Mickiewicza w Poznaniu
Ministerstwo Nauki i Szkolnictwa Wyższego