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Rhinoceros beetle (Trypoxylus dichotomus) males have pitchfork-shaped head horns, which they use to pry rival males from the trunks of trees. In the largest males these horns can be three times the length of horns in the two closest sister species. Because this weapon functions as a lever, longer horns should lift with less force than shorter horns (the ‘paradox of the weakening combatant’) unless other elements of the weapon system (e.g., input lever length, muscle mass) evolve to compensate. We used next-generation sequencing approaches to consolidate 23 sample locations into 8 genetically distinguishable populations, reconstructing their historical relationships and providing a comprehensive picture of the evolution of this horn lever system. We show that head horns likely increased in length independently in the Northern and Southern lineages. In both instances this resulted in weaker lifting forces, but this mechanical disadvantage was later ameliorated, to some extent and in some locations, by subsequent reductions to horn length, changes in muscle size, or by an increase in input lever length (head height). Our results reveal an exciting geographic mosaic of differences in weapon size, weapon force, and in the extent and nature of mechanical compensation. Reconstructing the evolution of this weapon system offers critical insights towards meaningfully linking mating system dynamics, selection patterns, and diversity in sexually selected traits.

This study determined the relationship between high school athletes’ maximal strength, jumping, and sprinting with shot put performance. High school athletes (n = 9; 16.9 ± 1 years; 110.4 ± 10.8 kg; 183.73 ± 9.33 cm) performed the broad jump, 1RM squat, 1RM bench, 40-yard dash with 10-yd split, and shot put. Strong positive correlations between shot put performance and broad jump (r = 0.89), 1RM squat (r = 0.90), and 1RM bench press (r = 0.87), and a strong negative correlation between shot put performance and 40-yd dash (r = −0.86) were observed. No significant correlation was found between shot put performance and 10-yd split times. Results indicate that shot put performance is associated with strength, jumping, and sprinting. It is valuable for coaches to understand relationships between physical fitness measurements, such as strength, power, and speed/acceleration, with shot put performance to predict competition performance, make training adjustments, and develop young throwers appropriately.

Sedimentologika is a community-driven Diamond Open Access scientific journal for the publication of work in the broad area of sedimentology and stratigraphy. The journal aims to provide a platform to the academic community and broader society, offering and guaranteeing permanent free publication and free access to peer-reviewed scientific studies focusing on all types of sedimentary processes, deposits, and environments across all spatial and temporal scales, on Earth or any other planetary body. It will publish high-quality research that will advance the field of sedimentary science (through multidisciplinarity, new teaching practices, tools and methods, and progress in accessibility to science). Sedimentologika is part of an ongoing broader Diamond Open Access movement in geosciences aspiring freedom from the financial barriers and pressures of private publishing houses, to provide direct and equal access to science for all citizens, scientists, and institutions worldwide. The published material will include research, review, methodology and opinion articles, which will be free to share, as the authors will retain the copyright on all the submitted material. Manuscripts will be published in English. Authors can attach a second abstract in the language of their choice, further allowing local communities, students, or decisional bodies to access, at least, a summary of the latest research, thus reducing potential language barriers. Sedimentologika follows Open Science principles to promote ethical dissemination and accessibility of science and knowledge, following high equity, diversity and inclusion standards. Sedimentologika emerged as a solution for the scientific community to sidestep structural inequality of the academic publishing system that is becoming financially unsustainable to its payers (authors, funding agencies), and to commit to bibliodiversity. The objective is to ensure that scientific findings remain accessible to all in order to keep advancing research and informing society on how we understand sedimentology and stratigraphy in the world around us. Sedimentologika is driven by the academic and scientific community for the community and society, promoting self-governance and adapting to the needs expressed by the community.

Sedimentologika is a community-driven Diamond Open Access (DOA) scientific journal about sedimentology. The journal aims to create a place where people can publish their research and access scientific studies on all types of sedimentary processes, methods, deposits, and environments, across all spatial and temporal scales, on Earth or any other planetary body, for free. The published material will be free to share (i.e., no embargo period) since authors retain the copyright. Sedimentologika is driven by the community for the community and is part of a broader DOA movement in geosciences. Sedimentologika aspires at emancipating from the financial barriers associated to private publishing houses to provide direct and equal access to science to all citizens, scientists, and institutions all over the globe. This journal will be defined by Open Science principles to promote ethical dissemination of science and knowledge, following high equality, diversity, and inclusion standards. Each step of the review and publication process will be visible and easy to follow for authors, reviewers and the community. Sedimentologika will be launched by mid-2022 and we are always looking for motivated people keen on giving a little bit of their time to make Sedimentologika a viable and recognized peer-reviewed scientific journal. Interested in this initiative? Come discuss with us!

Exopolymeric Substances (EPS) form biofilms in which the vast majority of prokaryotic organisms develop and thrive. They are ubiquitous, harbor metal and chemical species binding properties and can be the matrix for bio/orgamineralizations. Because of these properties, EPS have also been proposed as some of the most ancient traces of microbial life on Earth. They form sedimentary structures diagnostic of biological activity in some of the most ancient sedimentary rocks of the Archean. However, the metabolisms hosted by such ecosystems remain poorly understood given poor preservation and specificity of the available molecular, isotopic or fossilized signatures. Deep time paleobiological research therefore needs for new ways to unlock the history of the rare and variably preserved sedimentary rocks of these ages, by looking for new proxies that could help characterizing microbial ecosystems and better understand the co-evolution of the geosphere and the biosphere.We here attempt to describe trace metal signatures of a modern, arsenic-rich lacustrine microbial mat fueled by oxygenic and anoxygenic photosynthesis as an analog to better understand how microbial mats and their sedimentary and chemical signatures can be preserved in the Archean sedimentary record. We coupled in-situ imaging of a microbial mat from modern Dead Sea shore with SEM, Raman spectroscopy, and X-ray mapping, to (meta)genomics data and chemical analyses. Arsenic enrichments in the anoxygenic photosynthetic layer of the mat reached a 10’000-fold level, and was associated to Mg-Si-rich EPS. The latter ultimately mineralized into aragonite clusters with a co-enrichment of Sr, Mn and Mo. At the mat scale, the mineralized zone (rich in Fe, Sr and Ca from authigenic calcium carbonates and detrital clay) is clearly located above the As-enrichment layer, in association with Mn. These data support a chemically dynamic microbial mat where microbial activity, EPS chemical affinity and environmental processes lead to specific organic and mineralized chemical signatures linked to metabolic activity. Metagenomics and synchrotron-based speciation analyses shall confirm the links between elemental enrichments and the microbial metabolic pathways.We parallel this study to a well characterized microbial system of the Archean, the stromatolitic units of the Tumbiana Lake (2.72 Ga, Pilbara, Western Australia). In this environment, microbial mat accretionary behaviour has formed limestone stromatolites harboring layered nanopyrites embedded in carbonaceous material and chlorite (Marin-Carbonne et al., 2018). C, N and S isotopes of mineral fractions have suggested a connection of photosynthetic activity, sulfate reduction and methane cycling, potentially influenced by arsenotrophy (e.g. Thomazo et al., 2009; Sforna et al., 2014; Lepot et al., 2019). This is likely the most diverse undisputed microbial environment of the Archean. Our trace-elemental mapping using PIXE suggests co-enrichment of Mo and As in association to the nanopyrite-OM layer, that could be attributed to arsenotrophic and anoxygenic photosynthetic activity, in a similar fashion than argued for in the Dead Sea mat. Simulated diagenesis experiments are planned and should be able to provide chemical insights into the transformation of microbial mats to their fossilized counterparts at the microscale, to further validate the promises of metal biosignatures for reconstructing Archean ecosystems.

Background The transient and fragmented nature of the deep-sea hydrothermal environment made of ridge subduction, plate collision and the emergence of new rifts is currently acting to separate of vent populations, promoting local adaptation and contributing to bursts of speciation and species specialization. The tube-dwelling worms Alvinella pompejana called the Pompeii worm and its sister species A. caudata live syntopically on the hottest part of deep-sea hydrothermal chimneys along the East Pacific Rise. They are exposed to extreme thermal and chemical gradients, which vary greatly in space and time, and thus represent ideal candidates for understanding the evolutionary mechanisms at play in the vent fauna evolution. Results We explored genomic patterns of divergence in the early and late stages of speciation of these emblematic worms using transcriptome assemblies and the first draft genome to better understand the relative role of geographic isolation and habitat preference in their genome evolution. Analyses were conducted on allopatric populations of Alvinella pompejana (early stage of separation) and between A. pompejana and its syntopic species Alvinella caudata (late stage of speciation). We first identified divergent genomic regions and targets of selection as well as their position in the genome over collections of orthologous genes and, then, described the speciation dynamics by documenting the annotation of the most divergent and/or positively selected genes involved in the isolation process. Gene mapping clearly indicated that divergent genes associated with the early stage of speciation, although accounting for nearly 30% of genes, are highly scattered in the genome without any island of divergence and not involved in gamete recognition or mito-nuclear incompatibilities. By contrast, genomes of A. pompejana and A. caudata are clearly separated with nearly all genes (96%) exhibiting high divergence. This congealing effect however seems to be linked to habitat specialization and still allows positive selection on genes involved in gamete recognition, as a possible long-duration process of species reinforcement. Conclusion Our analyses highlight the non-negligible role of natural selection on both the early and late stages of speciation in the iconic thermophilic worms living on the walls of deep-sea hydrothermal chimneys. They shed light on the evolution of gene divergence during the process of speciation and species specialization over a very long period of time.

The hypersaline Dead Sea and its sediments are natural laboratories for studying extremophile microorganism habitat response to environmental change. In modern times, increased freshwater runoff to the lake surface waters resulted in stratification and dilution of the upper water column followed by microbial blooms. However, whether these events facilitated a microbial response in the deep lake and sediments is obscure. Here we investigate archived evidence of microbial processes and changing regional hydroclimate conditions by reconstructing deep Dead Sea chemical compositions from pore fluid major ion concentration and stable S, O, and C isotopes, together with lipid biomarkers preserved in the hypersaline deep Dead Sea ICDP-drilled core sediments dating to the early Holocene (ca. 10,000 years BP). Following a significant negative lake water balance resulting in salt layer deposits at the start of the Holocene, there was a general period of positive net water balance at 9500-8300 years BP. The pore fluid isotopic composition of sulfate exhibit evidence of intensified microbial sulfate reduction, where both δ34S and δ18O of sulfate show a sharp increase from estimated base values of 15.0‰ and 13.9‰ to 40.2‰ and 20.4‰, respectively, and a δ34S vs. δ18O slope of 0.26. The presence of the n-C17 alkane biomarker in the sediments suggests an increase of cyanobacteria or phytoplankton contribution to the bulk organic matter that reached the deepest parts of the Dead Sea. Although hydrologically disconnected, both the Mediterranean Sea and the Dead Sea microbial ecosystems responded to increased freshwater runoff during the early Holocene, with the former depositing the organic-rich sapropel 1 layer due to anoxic water column conditions. In the Dead Sea prolonged positive net water balance facilitated primary production and algal blooms in the upper waters and intensified microbial sulfate reduction in the hypolimnion and/or at the sediment-brine interface.

Changing redox conditions in water columns or sediment–water interfaces of lakes are captured as sedimentary archives, and are often influenced by climate. Their study therefore permits the reconstruction of past climate change on (sub-) annual to longer timescales. In Lago Fagnano (54°S Argentina/ Chile), a large oligotrophic and deep-oxygenated lake, alternations of light grey clay and dark greenish and black laminae are preserved throughout the Holocene sedimentary record. This study aims to clarify the mechanism of laminae formation and preservation in Lago Fagnano, and their relation to changing redox conditions in the lake. High-resolution major element scanning and mapping along with detailed mineralogical analyses of sediment cores allowed identifying Fe-oxides, Mn-oxides and Fe-(mono) sulphides as responsible for the lamination. Based on the interpretation of redox processes at the current sedimentary redox boundary and of buried palaeoredox fronts underlying mass-transported deposits, the greenish laminae enriched in Fe-oxides are interpreted as palaeo-redox fronts. The preservation of such former interfaces in Lago Fagnano sediments is most likely promoted by rapid increases of sedimentation due to higher runoff related to stronger Southern Hemisphere Westerlies. The formation of black laminae, showing only traces of Fe-(mono) sulphides and organic matter, is obscured by oxidation and early diagenetic processes, i.e. degradation and partial pyritization. These layers were presumably generated by small changes in bottom-water oxygenation due to reduced mixing and/or higher productivity. This study highlights the value of high-resolution sediment-geochemical analyses to better understand redox and diagenetic processes in oligotrophic mixed lakes.

The Office of Digital Research and Scholarship partners with members of the scholarly community at FSU and beyond to engage with and act on innovative ideas in teaching, research, and creative activity. We privilege marginalized voices and unique contributions to scholarly discourse. We support interdisciplinary inquiry in our shared pursuit of research excellence. We work with scholars to explore and implement new modes of scholarship that emphasize broad impact and access.Our dream is to create an environment where our diverse scholarly community is rewarded for engaging in innovative modes of research and scholarship. We envision a system of research communication that is rooted in open, academy-owned infrastructure, that privileges marginalized voices, and that values all levels and aspects of intellectual labor. In addition to the accomplishments related to our core work areas outlined in this report, we also developed an Anti-Racist Action Plan in 2020 and continue to work on enacting and periodically revising and updating the goals outlined therein.

As library publishers and open education programs grow, it is imperative that we integrate practices in our workflows that prioritize and include end users. Although there is information available on best practices for user testing and accessibility compliance, more can be done to give insight into the library publishing context. This study examines the user and accessibility testing workflow during the modification of an existing open textbook using Pressbooks at Texas Tech University.

Lake sediments bear valuable information allowing multidisciplinary research to address paleoclimatic and paleoenvironmental reconstructions at regional to global scales. Sedimentological, geochemical, paleontological and biological tools are commonly used to tackle these questions, which are generally driven by a set of intricated parameters. Among them, the importance of biogeochemical cycling is largely acknowledged in the lake (paleo-) water columns and has been at the heart of most paleolimnological studies. The way these signals are transferred to lake sediments has largely been studied. However, microbial communities - the principal actors in the biogeochemical cycling framework - keep being active in the sediment, and continue to influence the preservation and retention of organic and inorganic matter while buried. Gathered within the “early diagenesis” black box, these processes, once qualified, can help better interpret the proxies they may influence, and even constitute new ones. Within this work, we provide examples showing that the integration of studies of the subsurface biosphere within geo- and paleo-limnology investigations can help unlock or secure the potential of multiproxy analysis for reconstructing the paleoenvironments, paleoclimates and paleo-ecology of lake basins. The use of now well-developed OMICS methods, through the analysis of environmental and/or ancient DNA and lipids in particular has been coupled to mineralogical, isotopic and magnetic information in the Dead Sea (Levant) to demonstrate the differential preservation of mineralogic and sedimentologic signals along the last two glacial-interglacial cycles (Thomas et al., 2015, 2016; Ebert et al., 2018). Similar signals have been unlocked in Lake Towuti (Indonesia) and in Laguna Potrok Aike (Argentina) (Vuillemin et al., 2015, 2017). In Lake Ohrid (North Macedonia/Albania), environmental DNA has provided limited inputs on that perspective (Thomas et al., 2020), but has shown that ancient/fossil DNA could provide valuable information regarding the lake primary productivity and the status of its watershed land-cover. Integrating OMICS methods to tackle the identity and activity of the ancient and modern subsurface biosphere of lakes therefore holds an immense potential not only for microbiology investigations, but also for paleoclimatic and paleoenvironmental reconstructions.Ebert et al. (2018) Overwriting of sedimentary magnetism by bacterially mediated mineral alteration. Geology 46, 2–5.Thomas et al. (2016) Microbial sedimentary imprint on the deep Dead Sea sediment. The Depositional Record 1–21.Thomas et al. (2020) Weak influence of paleoenvironmental conditions on the subsurface biosphere of lake ohrid over the last 515 ka. Microorganisms 8, 1–20.Thomas et al. (2015) Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea. Geobiology 13, 546–561.Vuillemin et al. (2015) Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina. Biogeosciences Discussions 12, 18345–18388.Vuillemin et al. (2017) Preservation and Significance of Extracellular DNA in Ferruginous Sediments from Lake Towuti , Indonesia. Frontiers in Microbiology 8, 1–15.

International audience; The use of lake sedimentary DNA to track the long-term changes in both terrestrial and aquatic biota is a rapidly advancing field in paleoecological research. Although largely applied nowadays, knowledge gaps remain in this field and there is therefore still research to be conducted to ensure the reliability of the sedimentary DNA signal. Building on the most recent literature and seven original case studies, we synthesize the state-of-the-art analytical procedures for effective sampling, extraction, amplification, quantification and/or generation of DNA inventories from sedimentary ancient DNA (sedaDNA) via high-throughput sequencing technologies. We provide recommendations based on current knowledge and best practises.

INTRODUCTION Like the scholarly communication system it aims to transform, open advocacy work is broad in scope and reflects many influences, practices, and players. Despite having a rewarding mission, scholarly communication librarians frequently juggle multiple roles, may experience isolation and career stagnation, and produce outputs that are not readily understood. METHODS These challenges inspired the creation of the Open Action Kit, a suite of tools to help practitioners plan, execute, and assess open advocacy weeks, particularly Open Access Week. This resource sought to make explicit parallels between the activities and scope of open advocacy work and leadership skills that could aid in career progression. RESULTS The project’s aims and structure matured to focus on a broader, critical appraisal of the nature of scholarly communication work. Its encouragement of dialogue between its members and audience more thoroughly recognized and addressed the tensions between open advocacy work and professional success. DISCUSSION Open advocates expressed many frustrations with their work: they often felt isolated or burnt out, hindered by structures or expectations from their organization. While relational work is fundamental to the cultural change inherent in scholarly communication work, the overly simplistic, quantitative measures typical of library assessment do not accurately capture its nuance or complexity. CONCLUSION Centering the relational components of open advocacy work is necessary for it to be successful, sustainable, and appropriately valued. While the Open Action Kit has not been updated since 2017, it serves as a useful model for translating and centering relational work through distributed leadership, advocacy, and skill development.

Fe speciation and Fe isotopes have been widely used to reconstruct past basin dynamics and water redox conditions. However, sedimentation and early diagenesis of such proxies eventually alter any primary climate signal. In this work, we disentangled the processes occurring at the redox front below the sediment-water interface of a ventilated deep-water lake (Lago Fagnano, Argentina/Chile). A sequential extraction protocol was applied to characterize two reactive Fe pools: Fe oxyhydroxides and reduced iron. Subsequently Fe isotopes were constrained to determine the main processes mobilizing iron. At the redox front, ferric minerals reach a δ56Fe of -1.3 ‰ resulting from fluid upward migration and oxidation of dissolved Fe and likely following a Rayleigh distillation effect. Right below, low ferric Fe concentrations indicate Fe reduction which fuels the dissolved Fe pool. Consequently, as the sedimentation proceeds, light Fe is in constant upward migration along with the redox front. However, an increased sedimentation (e.g., turbiditic events) interrupts this dynamic cycle and the Fe rich redox front can be partially preserved. Additionally, oxidation of dissolved Fe is compromised and can be recycled in the formation of ferrous minerals, such as Fe monosulfides and amorphous phases, which show light Fe isotopes reaching a δ56Fe of -1.7 ‰

International audience; The present context of health crisis and unprecedented lockdown is an opportunity for thinking, position-taking, indignation and controversy. As a social activity, work redefines itself every day, according to circumstances. Work specialists, ergonomists included, observe and reflect. Contrary to certain preconceived ideas, Ergonomics is not primarily about so-called “ergonomic” chairs, desks or toothbrushes. Work is a central object of ergonomics, and the technical resources associated with it cover only some of the questions it raises. The ergonomic project consists of perceiving this Work; and above and beyond the technical resources, it is the values, skills, relationships, organizations, etc. that are its pivotal components, as is its inclusion in society, and therefore in the lives of each and every one of us.; En un contexto excepcional de confinamiento que ha llevado a un cambio en la vida personal y profesional de todos, la SELF inició la redacción de un texto, cuyo objetivo es contribuir a reflexiones y debates dentro de la comunidad de ergónomos y ergónomas, y en general de la sociedad. Contrariamente a ciertas ideas preconcebidas, la ergonomía no consiste principalmente en el diseño de sillas, escritorios o cepillos de dientes "ergonómicos". El trabajo es un objeto central de la ergonomía, y los recursos técnicos asociados con él cubren solo algunas de las preguntas que éste plantea. El proyecto ergonómico consiste en percibir este Trabajo más allá de los aspectos técnicos: los valores, habilidades, relaciones, organizaciones, etc. que son sus componentes fundamentales, como lo es su inclusión en la sociedad y, por lo tanto, en la vida de todos y cada uno de nosotros.

Here we present the first tephrostratigraphic, palaeomagnetic, and multiproxy data from a new ∼98 m-deep sediment core retrieved from the Fucino Basin, central Italy, spanning the last ∼430 kyr. Palaeoenvironmental proxy data (Ca-XRF, gamma ray and magnetic susceptibility) show a cyclical variability related to interglacial-glacial cycles since the Marine Isotope Stage (MIS) 12-MIS 11 transition. More than 130 tephra layers are visible to the naked eye, 11 of which were analysed (glass-WDS) and successfully correlated to known eruptions and/or other equivalent tephra. In addition to tephra already recognised in the previously investigated cores spanning the last 190 kyr, we identified for the first time tephra from the eruptions of: Tufo Giallo di Sacrofano, Sabatini (288.0 ± 2.0 ka); Villa Senni, Colli Albani (367.5 ± 1.6 ka); Pozzolane Nere and its precursor, Colli Albani (405.0 ± 2.0 ka, and 407.1 ± 4.2 ka, respectively) and Castel Broco, Vulsini (419–490 ka). The latter occurs at the bottom of the core and has been 40Ar/39Ar dated at 424.3 ± 3.2 ka, thus providing a robust chronological constrain for both the eruption itself and the base of the investigated succession. Direct 40Ar/39Ar dating and tephra geochemical fingerprinting provide a preliminary radioisotopic-based chronological framework for the MIS 11-MIS 7 interval, which represent a foundation for the forthcoming multiproxy studies and for investigating the remaining ∼110 tephra layers that are recorded within this interval. Such future developments will contribute towards an improved MIS 11-MIS 7 Mediterranean tephrostratigraphy, which is still poorly explored and exploited.

Many of us were hired to work toward systems where knowledge is open, equitable, transparent, and diverse. At the same time, our hiring institutions can be ambivalent about change, and we ourselves sometimes fall short of the ideals we espouse. One antidote for burnout and disillusionment is to build a durable, continuing community that can survive and do good work despite setbacks and failures. As JLSC editors, the three of us—Anne, Jennifer, and Rebekah—plan to continue facilitating the conversations that make this community a sustainable reality. The editorials below all engage with the idea of community. We hope that their thoughts and critiques will encourage all of us to think about our own communities and work to improve them. ispartof: Journal of Librarianship and Scholarly Communication vol:7 pages:1-15 status: Published online

Mixed cyanobacteria-dominated biofilms, enriched from a tributary of the M&eacute, rantaise (France) were used to conduct laboratory experiments in order to understand the relationship between the morphology of carbonate precipitates and the biological activity (e.g., cyanobacterial exopolymeric substances (EPS) production, photosynthetic pH increases). DNA sequencing data showed that the enriched biofilm was composed predominantly of two types of filamentous cyanobacteria that belonged to the Oscillatoriaceae and Phormidiaceae families, respectively. Microscopic analysis also indicated the presence of some coccoid cyanobacteria resembling Gloeocapsa. Analysis of carbonate precipitates in experimental biofilms showed three main morphologies: micro-peloids with different shapes of mesocrystals associated with Oscillatoriaceae filaments and theirs EPS, lamellae of carbonate formed directly on Phormidiaceae filaments, and rhombic sparite crystals wrapped in EPS. All crystals were identified by FT-IR spectroscopy as calcite. Similar structures as those that formed in laboratory conditions were observed in the microbial-tufa deposits collected in the stream. Microscopic and spectroscopic analysis of laboratory and natural samples indicated a close proximity of the cyanobacterial EPS and precipitated carbonates in both. Based on the laboratory experiments, we conclude that the microbial tufa in the stream is in an early stage of formation.

Changing redox conditions in lakes are captured in their sediments, and are often influenced by climate. Their study therefore allows tracing past climate change on (sub-) annual to longer time-scales. In Lago Fagnano (54°S Argentina/Chile), an oligotrophic and deep-ventilated soft-water lake, cyclic alternations of light grey clay and dark green to black laminae are preserved throughout the Holocene sedimentary record. This study aims at clarifying the mechanism, frequency, and climatic forcing of laminae formation and preservation in Lago Fagnano, and their relation to changing redox conditions in the lake. Using high-resolution XRF scanning and mapping, thin section, XRD and SEM analyses of sediment cores, Fe- and Mn-oxides were identified as generating the lamination on (sub-) decadal time-scales. Black and greenish laminae are interpreted as buried palaeo-oxidation fronts that underwent early diagenetic processes. The burial of redox fronts in Lago Fagnano is most likely promoted by cyclic rapid increases of sedimentation due to higher runoff and mass-wasting events. Increased runoff is related to the strength of the Southern Hemisphere Westerlies that, in turn, is modified by climate oscillations. Therefore, it is suggested that the cyclic repetition of the buried palaeo-redox fronts, showing periodicities of ~52 and ~4.5 years in the western and eastern sub-basins of Lago Fagnano, respectively, is forced by climate modes. The most likely candidates are the Antarctic Oscillation (AO) and the El Niño Southern Oscillation (ENSO), both impacting southernmost South America and showing similar sub-decadal modes and multi-decadal variations. Although the burial of redox fronts in lake or marine sediments is well-known, this study is the first to present a record of cyclic, high-frequency recurrence of these fronts most likely triggered by changing climate.

The significance of methane production by lakes to the global production of greenhouse gas is well acknowledged while underlying processes sustaining the lacustrine methane budget remain largely unknown. We coupled biogeochemical data to functional and phylogenetic analyses to understand how sedimentary parameters characterize the methane cycle vertically and horizontally in the ice-covered bay of the second largest lake in Europe, Lake Onego, Russia. Our results support a heterogeneous winter methane cycle, with higher production and oxidation closest to riverine inputs. Close to the river mouth, the largest numbers of copies of methane-related functional genes pmoA and mcrA were associated with a specific functional community, and methane production potential exceeded oxidation, resulting in 6–10 times higher methane fluxes than in the rest of the bay. The elevated fluxes arise from the spatial differences in quantity and type (lacustrine versus riverine sources) of organic matter. More homogeneity is found toward the open lake, where the sediment is vertically structured into 3 zones: a shallow zone of methane oxidation; a transitional zone (5–10 cm) where anaerobic methane oxidation is dominant; and a methane production zone below. This vertical pattern is structured by the redox gradient and human-induced changes in sedimentary inputs to the bay. Retrieved 16S rRNA gene sequences from Candidatus Methanoperedens and Cand. Methylomirabilis suggest that anaerobic oxidation of methane occurs in these freshwater lake sediments. ISSN:2044-205X ISSN:2044-2041