Search Results (255)

The lithological record of past climates and climate changes reveals significant potential in enhancing education and understanding of global climate changes and their impacts on contemporary societies. A relatively young geological record of Pleistocene cooling and glaciations serves as one of the most useful geo-educational tools. The present study encompasses a comprehensive review of ongoing efforts to assess and communicate the glacial geoheritage of the Pleistocene, with a detailed case study of Poland. A literature review is conducted to evaluate the extent of scientific work on inventorying and communicating the geodiversity of Pleistocene glacial and periglacial environments globally. The study demonstrates a steady increase in the number of scientific contributions focused on the evaluation and promotion of Pleistocene geoheritage, with a notable transition from the description of geosites to the establishment of geoconservation practices and educational strategies. The relative complexity of the palaeoclimatic record and the presence of glacial geodiversity features across extensive areas indicate that effective scientific communication of climate changes requires careful selection of a limited number of geodiversity elements and sediment types. In this context, the use of glacial erratic boulders and rock gardens for promotion of Pleistocene glacial geoheritage is advocated, and the significance of educational initiatives for local communities and the preservation of geocultural heritage is outlined in detail. Full article

The eastern North Pacific Ocean coastline (from the Salish Sea to the western Aleutian Islands) is highly glaciated with relic sediment deposits scattered throughout a highly contoured and variable bathymetry. Oceanographic conditions feature strong currents and tidal exchange. Sand wave fields are prominent features within these glaciated shorelines and provide critical habitat to sand lance (Ammodytes spp.). Despite an awareness of the importance of these benthic habitats, attributes related to their structure and characteristics remain undocumented. We explored the micro-bathymetric morphology of a subtidal sand wave field known to be a consistent habitat for sand lance. We calculated geomorphic attributes of the bedform habitat, analyzed sediment composition, and measured oceanographic properties of the associated water column. This feature has a streamlined teardrop form, tapered in the direction of the predominant tidal current. Consistent flow paths along the long axis contribute to well-defined and maintained bedform morphology and margin. Distinct patterns in amplitude and period of sand waves were documented. Strong tidal exchange has resulted in well-sorted medium-to-coarse-grained sediments with coarser sediments, including gravel and cobble, within wave troughs. Extensive mixing related to tidal currents results in a highly oxygenated water column, even to depths of 80 m. Our analysis provides unique insights into the physical characteristics that define high-quality habitat for these fish. Further work is needed to identify, enumerate, and map the presence and relative quality of these benthic habitats and to characterize the oceanographic properties that maintain these benthic habitats over time. Full article

Recent updates to the reconstructions of Cenozoic environmental changes (global sea level, temperature, and atmospheric carbon dioxide content) have made it intriguing to compare them to paleontological records for original interpretations. Paleogene brachiopods have remained in the shadow of their Paleozoic–Mesozoic predecessors, and the reactions of their diversity to the Earth’s dramatic changes are poorly understood. The present work aims to fill this gap via a comparison of several diversity and paleoenvironmental curves. The generic diversity was established by stages with two essentially different paleontological datasets, and several fresh paleoenvironmental reconstructions were adopted. It was observed that neither Paleogene eustatic fluctuations nor changes in the atmospheric carbon dioxide content correspond well to the generic diversity dynamics of brachiopods. The changes in the total number of genera and the global temperatures demonstrate similarity at the Danian–Ypresian interval, but not later. The fluctuations in the brachiopod diversity are near the same level during the Eocene–Oligocene, despite strong paleoenvironmental changes, implying the intrinsic resistivity of these organisms to external influences. Additionally, the Cretaceous/Paleogene mass extinction, the Paleocene–Eocene thermal maximum, and the Early Eocene optimum could enhance the diversity dynamics together with the long-term temperature changes. In contrast, the influences of the Late Danian warming event and the Oi-1 glaciation were not observed. Full article

Previous phylogeographic study of the root vole (Alexandromys oeconomus) revealed four mitochondrial cytochrome b lineages—North and Central European, North (=Central) Asian and Beringian. Three of them were studied in detail, while the North Asian lineage, which occupies the most extensive territory and is considered to be the place of origin for the species, was understudied. In the framework of the current study, we obtained 95 new sequences (34 localities) from the wide territory of Northern Asia and in total, examined 940 specimens from 181 localities throughout the species’ distribution range. The North Asian lineage was found to be more diverse than the Beringian and the European lineages. Southern Siberia and especially the Altai–Sayan region displayed the highest haplotype and nucleotide diversity, suggesting the region’s role as a genetic diversity hotspot. We suppose that the expansion of the North Asian lineage started from Western Transbaikalia. Its representatives colonised the territory from the Urals to the northern shore of the Okhotsk Sea, and then spread in the opposite direction, to Southern Siberia. As a result, a mixture of haplogroups is observed in the Altai–Sayan region. According to the BEAST analysis calibrated with the first A. oeconomus records, the MRCA of North Asian and Beringian lineages is dated back to ~0.82 Mya, and the first divergence within the North Asian lineage may have occurred ~0.6 Mya. When compared with colonisation times of other representatives of the Arvicolinae subfamily, our dating seems to be overestimated. In this regard, molecular data for dated fossil remains of the root vole are essential for subsequent studies. Full article

This paper presents the current state of knowledge on the Romanian Dendrocoelidae as part of the European/Palearctic Dendrocoelidae, emphasizing the contributions of the Romanian zoologists Radu Codreanu and Doina Balcesco. The main objective of this work was to identify the knowledge gaps for future alignment with current standards. This article presents the species inventory and a short historical overview of the classical phylogenetic system and discusses some morphological characters used in the systematics of the group. This study also analyzes the arguments (and hypotheses) put forward by Codreanu, Balcesco, and other authors regarding the phylogenetic value of various factors, including (a) the position of the oviducts between the male atrium and the bursal canal (typical for Paradendrocoelum); (b) the eyes and the penial flagellum in relation to the palaeogeographical context governed by the Quaternary Glaciation; and (c) the point of view of Codreanu and Balcesco on the origin and composition of the actual Romanian Dendrocoelidae fauna. The major key finding is that the Dendrocoelidae species in Romania should be reinvestigated in an integrative way, and specific research needs and future directions are suggested. Full article

As climate change alters subarctic ecosystems and human activities in Alaska, ecological baselines are critical for long-term conservation. We applied an ecoacoustic approach to characterize the ecological conditions of a rapidly deglaciating region in Kenai Fjords National Park, Alaska. Using automated recording units deployed at increasing distances from a road, we collected over 120,000 one-minute audio samples during the tourist seasons of 2021 and 2022. Ecoacoustic indices—Sonic Heterogeneity Index (SHI_tf), Spectral Sonic Signature (SSS), Weighted Proportion of Occupied Frequencies (wPOF), and Normalized Difference Sonic Heterogeneity Index (NDSHI)—were used to measure spatio-temporal patterns of the sonoscape. Results revealed higher sonic heterogeneity near the road attributed to technophony (vehicles) and geophony (wind) that spanned across the frequency spectrum, masking mid-high frequency biophony. Seasonal phenology and diel variations reflected ecological and human rhythms, including biophony from the dawn chorus from May–June, technophony from vehicle-based tourism from July–September, and decreased sonic activity in the form of geophonic ambience in October. Low-frequency geophonies were prevalent throughout the sonoscape with more natural sounds at greater distances from the road. Our findings demonstrate the benefits of using ecoacoustic methods to assess ecosystem dynamics for establishing ecological baselines useful for future comparisons in rapidly changing environments. Full article

Coastal shellfish farming areas in northern China seas face frequent starfish outbreaks, particularly from Asterias amurensis and Patiria pectinifera, leading to significant economic losses. Genomic data are key to understanding the population dynamics and adaptive traits and developing effective control measures for these species. Here, we characterized and compared the genomic information of these two starfish using a whole-genome survey approach. The genome size of A. amurensis is ~477 Mb with 1.52% heterozygosity, 53.60% repetitive sequences, and 39.94% GC content, while P. pectinifera has a ~529 Mb genome, 2.90% heterozygosity, 56.02% repetitive sequences, and 40.63% GC content. Scaffold N50 values were 1823 bp for A. amurensis and 1328 bp for P. pectinifera. We identified 161,786 microsatellite motifs in A. amurensis and 316,245 in P. pectinifera, with mononucleotide repeats being the most common. A total of 171 single-copy homologous genes were found in A. amurensis, with 94 in P. pectinifera. For both species, KEGG annotation showed functional similarities in glycan biosynthesis, translation, metabolism, catabolism, and transport. The Pairwise Sequentially Markovian Coalescent (PSMC) analysis unveiled a bottleneck effect during the Pleistocene glaciation. Additionally, phylogenetic analysis of mitochondrial genomes indicates that P. pectinifera and Patiria miniata of the same genus belong to the same branch in the evolutionary tree as sister groups with the closest genetic relationship, while A. amurensis is most closely related to Astropecten polyacanthus within the class Asteroidea. These findings provide valuable genomic insights for both species. Full article

The deposition and evolution of ice-rich materials on Martian surfaces offer valuable insights into climatic evolution and the potential driving forces behind global climate change. Substantial evidence indicates that the mid-latitudes of Mars played a crucial role in the formation and development of glacial and periglacial landforms during the Amazonian period. However, few studies have comprehensively examined ice-related landforms in the low-latitude region of Mars. Whether extensive glacial activity has occurred in the equatorial region of Mars and whether there are any potential geological records of such activities remain unclear. In this study, we analyzed remote sensing data from the Martian equatorial region (0°–±30°) and identified existing glacial/periglacial features, as well as remnant landforms of past glaciation. Our findings reveal that glaciation at low latitudes is more widespread than previously thought, with ice-related remnants extending as far equatorward as 13°N in the northern hemisphere and 19°S in the southern hemisphere, highlighting a broader latitudinal range for ice-related landforms. These landforms span multiple episodes of Martian geological history, supporting the hypothesis on the occurrence of repeated glaciation and various high-obliquity events. Evidence of dynamic interactions between ice deposition and sublimation in low-latitude regions demonstrates substantial ice loss over time, leaving ice-related remnants that provide valuable insights into Mars’ climatic evolution. Based on volumetric estimates of the concentric crater fill (CCF), the low-latitude regions of Mars may contain up to 1.05 × 10³ km³ of ice. This corresponds to a global equivalent ice layer thickness ranging from 21.7 mm (assuming a pore ice with 30% ice content) to 65.1 mm (assuming glacial ice with 90% ice content), suggesting a potentially greater low-latitude ice reservoir than previously recognized. Full article

Clouds play a central role in regulating incoming solar radiation and outgoing terrestrial emission; hence, they must be internally constrained to prognose Earth’s temperature. At the same time, planetary fluids are inherently turbulent, so the climate state would tend toward maximum entropy production—a generalized second law of thermodynamics. Incorporating these requirements, I have previously formulated an aquaplanet model to demonstrate that intrinsic water properties may strongly lower the climate sensitivity to solar irradiance, thereby resolving the faint young Sun paradox (FYSP). In this paper, I extend the model to include other external forcings and show that sensitivity to the reduced outgoing longwave radiation by the elevated pCO₂ can be several times greater, but the global temperature remains capped at ~40 °C by the exponential increase in saturated vapor pressure. I further show that planetary albedo augmented by a tropical supercontinent may cool the climate sufficiently to cause tropical glaciation. And since the glacial edge is marked by above-freezing temperature, it abuts an open, co-zonal ocean, thereby obviating the “Snowball Earth” hypothesis. Our theory thus provides a unified framework for interpreting Earth’s diverse climates, including the FYSP, the warm extremes of the Cambrian and Cretaceous, and the tropical glaciations of the Precambrian. Full article

Silverside fishes in Chile, abundant in marine and freshwater habitats, are classified in two genera: Odontesthes and Basilichthys. Both genera have widespread distributions across southern South America, with marine origins. Despite extensive information on Chilean freshwater silversides and their overlapping distributions along a latitudinal gradient, their taxonomy and diversification remain contentious. This study examines the diversity of Chilean silversides using RADseq genomic data from 78 Odontesthes and 60 Basilichthys individuals, covering most of their range. The phylogenetic and structural analyses of approximately 20,000 SNPs reveal some geographic variation but indicate no differentiation between Odontesthes mauleanum and O. brevianalis. The genus Basilichthys, in contrast, presents a disjunct distribution, with populations in coastal rivers of Peru (B. semotilus) that are separated from Chilean populations by the Atacama Desert. Chilean Basilichthys, traditionally classified as B. microlepidotus and B. australis until 2012, also show no genetic differentiation consistent with species boundaries but exhibit latitudinal differences consistent with isolation by distance. The contrasting patterns of genetic differentiation exhibited by species of these genera may be explained by the more frequent exchange with marine species for Odontesthes that do not occur in Basilichthys, in addition to the recent geological history of glaciations affecting the southern range of their distribution. Full article

Glacial retreat is a widely recognised phenomenon, and yet the processes of glaciofluvial bedload in high-alpine river systems remain largely unobserved. This study investigates the impact of hydrological and climatic changes on bedload and water discharge dynamics in the Rofenache catchment in the Ötztal Alps over a 14-year period. Utilising high-resolution bedload data from plate geophones and direct calibration measurements, we analyse water discharge and bedload transport, focusing on hysteresis events influenced by temperature and precipitation. Our findings reveal that water discharge and bedload transport processes are non-linear, with counterclockwise hysteresis dominating; this is consistent with previous studies in glaciated catchment areas. The inclusion of temperature and precipitation data further highlights the significant influence of temperature on hysteresis events in the catchment area. This research provides insights into the bedload dynamics of a high-alpine river under the effects of climate change, emphasising the need for continued monitoring and analysis to understand the evolving interactions between hydrological and sedimentological processes and climatic factors in partially glaciated catchments. Full article

The Quercus genus is found across a broad latitudinal range, and its spread in heterogeneous ecosystems is influenced by environmental, genetic, and anthropogenic factors. However, Mediterranean oak ecosystems, in particular, have been significantly impacted by climate-driven shifts. These shifts reshape the composition and spatial configuration of a great number of species. Here, this study evaluates the impact of climate change on the habitat suitability of Valonia oak (Quercus ithaburensis subsp. macrolepis (Kotschy) Hedge & Yalt.) and particularly focuses on understanding whether its population is native or was introduced to the Karagüney Mountains, Türkiye. Using ecological niche modeling with MaxEnt and climate data from CHELSA-TraCE21k (a 1 km climate time series), we built 120 models to analyze the habitat suitability of Valonia oak across different climatic periods from the Last Glacial Maximum (LGM) (21 ka BP) to the present. The results indicate that habitat suitability is primarily influenced by temperature- and precipitation-related variables. In fact, temperature fluctuations clearly affect the target species of this study. The most significant factors are the mean diurnal temperature range (bio2; 33.1%), precipitation in the wettest month (bio13; 19%), and mean annual temperature (bio1; 16.7%). Paleoclimatic predictions show that suitable habitats contracted during the early Holocene but expanded afterward, with current distributions aligning more closely with the natural range. In other words, it can be stated that Valonia oak’s habitat suitability has gradually improved from the LGM to the present, with both the total and natural ranges expanding over time. The results indicate that the species has demonstrated long-term stability, resilience, and adaptability to climate change, making it a potential alternative species for future climate scenarios. In addition, the data support the hypothesis that the species’ population in the Karagüney Mountains is relict, but was previously unrecognized as native. This study improves our knowledge about the distribution and environmental preferences of Valonia oak, which is important for underpinning its conservation strategies. Full article

Anemone altaica Fisch. ex C. A. Mey., a component of the tertiary boreo-nemoral vegetation complex, exhibits a disjunct distribution from European Russia to Central China. The Khamar-Daban Ridge, extending along Lake Baikal’s southern coast, has served as a refugium preserving mesophilic forest remnants in South Siberia since the Pleistocene. This study aimed to elucidate the phylogenetic relationships and historical biogeography of A. altaica within the Khamar-Daban refugium using plastid DNA markers (trnL + trnL-trnF). Phylogenetic and mismatch distribution analysis revealed polyphyly (more specifically diphyly) among A. altaica lineages, suggesting past hybridization events with related species followed by backcrossing. Estimation of isolation by distance effect, spatial autocorrelation analysis, PCoA, and AMOVA indicated a clear spatial genetic structure for A. altaica on the Khamar-Daban Ridge. The most reliable geographical model suggests that during periods of Pleistocene cooling, A. altaica persisted in at least six microrefugia within the ridge. Populations associated with these microrefugia formed western, central, and eastern genetic supergroups with limited gene flow among them. Gene flow likely occurred more easily during glaciations or early interglacials when the subalpine zone shifted closer to Lake Baikal due to the depression of the snow boundary, allowing adjacent populations to intermingle along the glacial edges and terminal moraines in mountain forest belt. Full article

The interglacial period of the Cryogenian glaciation is a pivotal interval in geological history, marked by two “Snowball Earth” events and the emergence of early animals. Currently, there is considerable debate regarding the paleo-oceanic environment and the dominant factors controlling organic matter enrichment. Here, based on inorganic geochemical data and mineral composition from the Datangpo Formation in Xiangtan (South China), combined with previous research, we have analyzed the paleo-climate, redox condition, seawater restriction, and primary productivity across different sedimentary facies during this critical interval. The results exhibit that the Datangpo Formation can be divided into three members (Da1–Da3) based on lithology. Paleoclimatic proxies suggest the environment was relatively cold during the deposition of the Da-1 Member, while it was relatively warm and humid during the deposition of the Da 2–3 members. Compared to shallow water areas, deep-water areas experienced a more rapid transition in paleotemperature following the Sturtian glaciation event. Combining Mo-U elements, Ce_N/Ce*_N, and C_org/P ratios, the environment was characterized by an oxic environment during the early deposition period of the Datangpo Formation, then gradually transitioned to suboxic, and finally anoxic conditions. Furthermore, the decompression of terrestrial magma chambers led to intense volcanic/hydrothermal activity during the deglaciation period. Hydrothermal activity was most intense during the Da-1 depositional period, followed by Da-2, and gradually declined during Da-3 depositional period. Hydrothermal activity not only provided essential materials for the formation of Mn carbonate ores but also significantly enhanced the primary productivity by introducing large amounts of nutrients in the paleo-ocean. The primary productivity indicators (Ni/Al, Cu/Al) exhibited an obvious coupling with Ce_N/Ce*_N and C_org/P ratios in the Datangpo Formation, indicating that oxygen-rich environments were favorable for biological proliferation, thereby providing abundant organic matter. Anoxic conditions further facilitated the preservation of organic matter, which may be the primary factor driving organic matter enrichment in the Datangpo Formation. Full article

Although the Late Pleistocene glaciation history of the Fraser Lowland (BC, Canada) is relatively well studied, little is known about ice-flow directions during the last glaciation (Fraser glaciation). Lidar imagery from the western Fraser Lowland was used to identify and interpret previously unrecognized glacial landforms in a heavily urbanized and vegetated area. This indicates patterns of ice flow during the latest stage of the Fraser glaciation (Vashon stade) of the Cordilleran Ice Sheet. The imagery provides a picture of dominant SSE flow from the Strait of Georgia in the western part of the study area, and SSW flow from the southern Coast Mountain valleys in the eastern part, resulting in an overall southward flow, as documented in the uplands in the southern part of our study area. No evidence for a substantially different ice flow could be identified. Three new radiocarbon ages from the Sechelt area ca. 40 km northwest of the Fraser Lowland indicate a proximal ice margin in the Strait of Georgia already ca. 30 cal ka BP, well before the Coquitlam ice advance in the Fraser Lowland. These ages contribute to the unsolved discussion if this ice margin advanced onto the Fraser Lowland, yet further studies are needed. Full article