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Soil carbon loss is likely to increase due to climate warming, but microbiomes and microenvironments may dampen this effect. In a 30-year warming experiment, physical protection within soil aggregates affected the thermal responses of soil microbiomes and carbon dynamics. In this study, we combined metagenomic analysis with physical characterization of soil aggregates to explore mechanisms by which microbial communities respond to climate warming across different soil microenvironments. Long-term warming decreased the relative abundances of genes involved in degrading labile compounds (e.g. cellulose), but increased those genes involved in degrading recalcitrant compounds (e.g. lignin) across aggregate sizes. These changes were observed in most phyla of bacteria, especially for Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, and Planctomycetes. Microbial community composition was considerably altered by warming, leading to declined diversity for bacteria and fungi but not for archaea. Microbial functional genes, diversity, and community composition differed between macroaggregates and microaggregates, indicating the essential role of physical protection in controlling microbial community dynamics. Our findings suggest that microbes have the capacity to employ various strategies to acclimate or adapt to climate change (e.g. warming, heat stress) by shifting functional gene abundances and community structures in varying microenvironments, as regulated by soil physical protection.

Integrated solutions to the climate and biodiversity crises—together with other global sustainability challenges—include the identification, design and implementation of nature‐based solutions (NbS). Living organisms mediate biogeochemical cycles and greenhouse gas fluxes from land and sea, and provide NbS to both climate change mitigation and adaptation. Plants, as the primary producers in ecosystems, lie at the heart of NbS. Plant ecology provides the foundation for developing and evaluating NbS based on an understanding of the ecological processes that underlie ecosystem service flow to people. In this Special Feature, we provide a collection of mini‐reviews that presents concise and focused analysis of the plant ecology of NbS. The mini‐reviews highlight key insights, challenges and opportunities for future research. The development of NbS that target specific ecosystem functions (e.g. carbon storage), or aim at increasing ecosystem resilience against perturbations (e.g. those associated with climate change), requires unification of ecological theory from areas such as biodiversity‐ecosystem function, plant–animal interactions, resilience and functional traits of organisms. Synthesis. Plant ecology and nature‐based solutions (NbS) research are complementary. Plant ecology can inform the design and management of effective NbS, and provide insights for the creation of novel ecosystems that provide NbS; while learning from the implementation of NbS can progress theory. To deploy NbS at the speed and scale needed to mitigate and adapt to climate change, we must rapidly integrate ecological concepts into the design of NbS. At the same time, the design and deployment of NbS in different ecological contexts provides an unprecedented opportunity to learn how performances of individual NbS sites can be explained in an integrated way, leading to the development of general concepts. Ultimately, a mechanistic understanding of how plants and their functional traits contribute to ecosystem function and service provision is critical for the design, verification of benefits from and avoidance of adverse effects of NbS. [ABSTRACT FROM AUTHOR]

Biogenic silica (biogenic Si) is a bioactive component crucial for the biogeochemical cycling of Si in terrestrial and aquatic ecosystems. Its formation and dissolution dynamics are intricately linked to carbon (C) cycling. However, knowledge about the source, composition, and factors controlling the distribution of biogenic Si in coastal wetland sedimentary environments is still limited. To address this lack of knowledge, we introduced a suite of geometric models for biogenic Si biovolume calculation and investigated biogenic Si assemblages, along with biogenic Si and biogenic Si‐occluded C contents, in sediments from representative coastal wetlands along the west coast of Bohai Bay. Our analysis showed that sedimentary biogenic Si predominantly derived from phytoliths (78.1% ± 5.8%), diatoms (18.2% ± 4.8%), and sponge spicules (3.7% ± 2.9%). Notably, phytolith assemblages were primarily composed of forms derived from the Poaceae family. The biogenic Si‐occluded C content (0.035–1.870 g kg−1) within these wetland sediments was consistent across both sites, accounting for 0.97–5.71% of the total organic C pool. Structural equation modeling indicated that total organic C, pH, and amorphous aluminum oxides either directly or indirectly influenced the biogenic Si content in coastal wetlands sediments. These results demonstrate the critical role that biogenic Si plays in the Si biogeochemical cycle and provide valuable information that advances our understanding of the biogeochemical interactions between Si and C in coastal wetland ecosystems. [ABSTRACT FROM AUTHOR]

Background: Multiheme cytochromes c (MHC) provide prokaryotes with a broad metabolic versatility that contributes to their role in the biogeochemical cycling of the elements and in energy production in bioelectrochemical systems. However, MHC have only been isolated and studied in detail from a limited number of species. Among these, Desulfuromonadia spp. are particularly MHC-rich. To obtain a broad view of the diversity of MHC, we employed bioinformatic tools to study the cytochromome encoded in the genomes of the Desulfuromonadia class. Results: We found that the distribution of the MHC families follows a different pattern between the two orders of the Desulfuromonadia class and that there is great diversity in the number of heme-binding motifs in MHC. However, the vast majority of MHC have up to 12 heme-binding motifs. MHC predicted to be extracellular are the least conserved and show high diversity, whereas inner membrane MHC are well conserved and show lower diversity. Although the most prevalent MHC have homologues already characterized, nearly half of the MHC families in the Desulforomonadia class have no known characterized homologues. AlphaFold2 was employed to predict their 3D structures. This provides an atlas of novel MHC, including examples with high beta-sheet content and nanowire MHC with unprecedented high numbers of putative heme cofactors per polypeptide. Conclusions: This work illuminates for the first time the universe of experimentally uncharacterized cytochromes that are likely to contribute to the metabolic versatility and to the fitness of Desulfuromonadia in diverse environmental conditions and to drive biotechnological applications of these organisms. [ABSTRACT FROM AUTHOR]

Recent decadal trends of deoxygenation in the global ocean interior have resulted in the expansion and shoaling of oxygen minimum zones (OMZs). When the OMZs upper bound nears the euphotic zone a unique community of phytoplankton, residing in extremely low light (<0.1% surface irradiance) and dissolved oxygen concentrations (<1-2 µmol kg-1), can appear. In this minireview paper we synthesize our current understanding of the phytoplankton community that resides in an OMZ chlorophyll maximum (OMZ-CM), below the depths of the deep chlorophyll maximum found in permanently and seasonally stratified regions, and its role in OMZ biogeochemical cycles. Uncultivated basal lineages of the cyanobacterium Prochlorococcus dominate this community, forming an OMZ-CM that can contribute to integrated stocks of chlorophyll a, in some cases with a similar magnitude to the deep chlorophyll maximum. Photosynthesis by Prochlorococcus in the OMZ-CM provides a significant source of oxygen, that fuels the aerobic oxidation of nitrite and organic matter, impacting elemental biogeochemical cycling, including that of carbon and nitrogen. Yet, on a global scale, there is a lack of understanding and quantification of the spatial distribution of these OMZ-CM, their stocks of phytoplankton, their influence on fluxes of carbon and nitrogen, and how these may respond to climate change. Monitoring the dynamics of the OMZ-CM and biogeochemical cycles in OMZs is challenging, and requires a multidisciplinary approach, combining ship-based observations with autonomous platforms, satellite data, and conceptual models. Only then can the implications of enhanced deoxygenation on the future marine ecosystem be understood. [ABSTRACT FROM AUTHOR]

The editorial "Insights in aquatic microbiology: 2023" published in Frontiers in Microbiology explores the diverse interactions and dynamics of microorganisms in aquatic ecosystems. The research covers various environments, from oceans to lakes, rivers, and other water bodies, focusing on nutrient cycling, energy flow, and ecosystem health. The publication highlights recent findings in freshwater and saltwater ecosystems, emphasizing the importance of understanding microbial communities for environmental conservation and management. The editorial also calls for the adoption of new technologies and interdisciplinary collaboration to advance research in aquatic microbiology and address environmental challenges effectively. [Extracted from the article]

The continental bedrock contains groundwater-bearing fractures that are home to microbial populations that are vital in mediating the Earth's biogeochemical cycles. However, their diversity is poorly understood due to the difficulty of obtaining samples from this environment. Here, a groundwater-bearing fracture at 975 m depth was isolated by employing packers in order to characterize the microbial community via metagenomes combined with prokaryotic and eukaryotic marker genes (16S and 18S ribosomal RNA gene). Genome-resolved analyses revealed a community dominated by sulfate-reducing Bacillota, predominantly represented by Candidatus Desulforudis audaxviator and with Wood-Ljungdahl as the most prevalent pathway for inorganic carbon fixation. Moreover, the eukaryotic community had a considerable diversity and was comprised of mainly flatworms, chlorophytes, crustaceans, ochrophytes, and fungi. These findings support the important role of the Bacillota, with the sulfate reducer Candidatus Desulforudis audaxviator as its main representative, as primary producers in the often energy-limited groundwaters of the continental subsurface. Metagenomics combined with 16S and 18S ribosomal RNA sequencing on groundwater retrieved from a packer-isolated borehole provide insights into the microbial community at 975 m depth. [ABSTRACT FROM AUTHOR]

Plant economics, the way plants allocate and utilize resources, affect multiple soil processes through interactions with root and associated microbial communities. However, the interplay between plant economics and microbial ecological strategies remains poorly understood, which is crucial for integrated manipulation of plant‐ and microbe‐mediated functions in mitigating climate change and sustaining soil health. We used a field experiment with 11 cover crop species grown monocultures in the same base soil to test whether microbial ecological strategies are associated with plant economic strategies and if their interactions are linked to soil functions. A principal component analysis (PCA) was performed on root and leaf traits to identify the loadings of cover crop species on the plant trait space. Metagenomic analysis of rhizosphere microbial communities was conducted to infer their ecological strategies based on genetically encoded community‐aggregated traits. We found a synchronous relationship between the conservation gradient of plant economic strategies and the trade‐offs in microbial ecological strategies. Conservative plant strategists, such as Lolium multiflorum, Triticum turgidum and Brassica juncea, fostered microbial communities characterized by high growth yield potentials (Y‐strategies). This included increased microbial carbon fixation pathways, citrate cycle, ribosome and valine, leucine and isoleucine biosynthesis. As a result, microbial metabolic efficiency improved, shown by higher microbial biomass carbon content and a lower metabolic quotient (qCO2), led to enhanced soil organic carbon accumulation. In comparison, acquisitive plants like Astragalus sinicus, Vicia villosa, Trifolium incarnatum and Medicago sativa stimulated microbial resource‐acquisition strategies (A‐strategies). This included enhanced bacterial chemotaxis, secretion systems, biotin metabolism and cell motility pathways, which in turn increased soil exoenzyme activity and accelerated soil nitrogen mineralization. Consequently, these species enhanced soil nitrogen availability and had substantial feedbacks on subsequent main crop productivity. Synthesis. This study demonstrates how plant economic strategies influence the balance between different microbial ecological strategies, specifically the trade‐offs in Y‐ and A‐strategies. These interactions exert control over carbon and nitrogen dynamics in the soil ecosystem. The findings provide insights for implementing nature‐based solutions to improve agroecosystem management practices. [ABSTRACT FROM AUTHOR]

Opal and calcium carbonate are thought to regulate the biological pump's transfer of organic carbon to the deep ocean. A global sediment trap database exhibits large regional variations in the organic carbon flux associated with opal flux. These variations are well‐explained by upper ocean silicate concentrations, with high opal 'ballasting' in the silicate‐deplete tropical Atlantic Ocean, and low ballasting in the silicate‐rich Southern Ocean. A plausible, testable hypothesis is that opal ballasting varies because diatoms grow thicker frustules where silicate concentrations are higher, carrying less organic carbon per unit opal. The observed pattern does not fully emerge in an advanced ocean biogeochemical model when diatom silicification is represented using a single global parameterization as a function of silicate and iron. Our results suggest a need for improving understanding of currently modeled processes and/or considering additional parameterizations to capture the links between elemental cycles and future biological pump changes. Plain Language Summary: Opal, or hydrated silica, is taken up in the surface ocean by diatoms to construct their protective frustules. Another plankton type, coccolithophores, generate protective platelets from calcium carbonate. These two minerals, and thereby plankton types, play major roles in the global carbon cycle. The 'biological carbon pump' transfers carbon from the upper ocean to the ocean's depths, where it can stay for millenia. This process has influenced past atmospheric carbon dioxide concentrations and could also do so in the future. The transfer of carbon to the deep ocean is partially regulated by the amount of 'ballast' minerals in sinking particles, especially opal and calcium carbonate, which are denser and cause particles to sink faster and/or protect organic carbon from microbial consumption. We show that unlike calcium carbonate, opal's ballasting effect varies a great deal between different regions of the ocean. The variation in opal ballasting is well‐explained by the upper‐ocean concentration of silicate between these regions. This suggests a simple explanation: when silicate concentrations are high, diatoms grow thick frustules which actually results in lower carbon sinking per unit opal. Capturing this ballasting–silicate relationship in carbon cycle models may improve their ability to predict future biogeochemical cycles and climate. Key Points: Opal ballasting varies by more than a factor of six across ocean regions; calcium carbonate ballasting is uniformSilicate concentration predicts opal ballasting which suggests that the latter varies with diatom frustule thicknessThis emergent relationship's absence from a sophisticated biogeochemical model indicates it holds useful information for constraining models [ABSTRACT FROM AUTHOR]

This short communication explores the urban geology sub-field, which emerges as a crucial discipline to address the dynamic interaction between human activities, geological processes, and environmental sustainability. It aims to guide land use planning, assess and mitigate the impacts of urbanization on natural resources, evaluate geological hazards, address geoenvironmental problems, and enhance public awareness. The correspondence also touched upon urban geochemistry, a relatively nascent interdisciplinary sub-field, elucidating its role in studying trace element characteristics, human activities' impacts on the environmental quality, and the influence on biogeochemical cycles. Despite its significance, urban geology faces underappreciation and challenges, particularly in African megacities. Inadequate funding, data collection difficulties, and a lack of awareness hinder its promotion. Therefore, we advocate for increasing the collaboration between academic institutions, research centers, and governmental authorities to overcome these barriers and promote multidisciplinary research projects for a holistic understanding of the complexities of the urban environments. [ABSTRACT FROM AUTHOR]

Rainforests provide vital ecosystem services that are underpinned by plant-soil interactions. The forests of Borneo are globally important reservoirs of biodiversity and carbon, but a significant proportion of the forest that remains after large-scale agricultural conversion has been extensively modified due to timber harvest. We have limited understanding of how selective logging affects ecosystem functions including biogeochemical cycles driven by soil microbes. In this study, we sampled soil from logging gaps and co-located intact lowland dipterocarp rainforest in Borneo. We characterised soil bacterial and fungal communities and physicochemical properties and determined soil functioning in terms of enzyme activity, nutrient supply rates, and microbial heterotrophic respiration. Soil microbial biomass, alpha diversity, and most soil properties and functions were resistant to logging. However, we found logging significantly shifted soil bacterial and fungal community composition, reduced the abundance of ectomycorrhizal fungi, increased the abundance of arbuscular mycorrhizal fungi, and reduced soil inorganic phosphorous concentration and nitrate supply rate, suggesting some downregulation of nutrient cycling. Within gaps, canopy openness was negatively related to ectomycorrhizal abundance and phosphomonoesterase activity and positively related to ammonium supply rate, suggesting control on soil phosphorus and nitrogen cycles via functional shifts in fungal communities. We found some evidence for reduced soil heterotrophic respiration with greater logging disturbance. Overall, our results demonstrate that while many soil microbial community attributes, soil properties, and functions may be resistant to selective logging, logging can significantly impact the composition and abundance of key soil microbial groups linked to the regulation of vital nutrient and carbon cycles in tropical forests. [ABSTRACT FROM AUTHOR]

Throughout the western tropical Pacific Ocean, eddies and currents play an important role in biogeochemical cycling. Many studies have investigated the effects of hydrography on vertical patterns of picophytoplankton and heterotrophic bacterial abundance in mesoscale eddies. There is a lack of field observations to determine what impact dynamic hydrological systems of eddies have on prokaryotic community activity (growth and mortality rates). An objective of this study was to examine how anticyclonic eddies influence picoplankton abundance and activity (growth and mortality rates). To meet this purpose, heterotrophic bacterial and picophytoplankton growth and mortality rates were examined by modified dilution experiments conducted at the surface, deep chlorophyll maximum (DCM), and 200 m depth outside (OE) and inside of warm eddies core (EC) in the west Pacific Ocean. A high heterotrophic bacterial grazing rate was found in the EC region in the present study. Furthermore, the picophytoplankton grazing rate in EC was frequently greater than the grazing rate in OE. Furthermore, the higher grazing rates in the EC region cause a lower proportion of viral lysis to account for heterotrophic bacteria and picophytoplankton mortality. The results of our experiments suggest that downwelling in EC might increase picophytoplankton growth and grazing rates, increasing the carbon sink in the warm eddy and potentially increasing ocean carbon storage. [ABSTRACT FROM AUTHOR]

Introduction: In riverine ecosystems, dynamic interplay between hydrological conditions, such as flow rate, water level, and rainfall, significantly shape the structure and function of bacterial and microeukaryotic communities, with consequences for biogeochemical cycles and ecological stability. Lake Taihu, one of China’s largest freshwater lakes, frequently experiences cyanobacterial blooms primarily driven by nutrient over-enrichment and hydrological changes, posing severe threats to water quality, aquatic life, and surrounding human populations. This study explored how varying water flow disturbances influence microbial diversity and community assembly within the interconnected river–lake systems of the East and South of Lake Taihu (ET&ST). The Taipu River in the ET region accounts for nearly one-third of Lake Taihu’s outflow, while the ST region includes the Changdougang and Xiaomeigang rivers, which act as inflow rivers. These two rivers not only channel water into Lake Taihu but can also cause the backflow of lake water into the rivers, creating distinct river–lake systems subjected to different intensities of water flow disturbances. Methods: Utilizing high-throughput sequencing, we selected 22 sampling sites in the ET and ST interconnected river-lake systems and conducted seasonally assessments of bacterial and microeukaryotic community dynamics. We then compared differences in microbial diversity, community assembly, and co-occurrence networks between the two regions under varying hydrological regimes. Results and discussion: This study demonstrated that water flow intensity and temperature disturbances significantly influenced diversity, community structure, community assembly, ecological niches, and coexistence networks of bacterial and eukaryotic microbes. In the ET region, where water flow disturbances were stronger, microbial richness significantly increased, and phylogenetic relationships were closer, yet variations in community structure were greater than in the ST region, which experienced milder water flow disturbances. Additionally, migration and dispersal rates of microbes in the ET region, along with the impact of dispersal limitations, were significantly higher than in the ST region. High flow disturbances notably reduced microbial niche width and overlap, decreasing the complexity and stability of microbial coexistence networks. Moreover, path analysis indicated that microeukaryotic communities exhibited a stronger response to water flow disturbances than bacterial communities. Our findings underscore the critical need to consider the effects of hydrological disturbance on microbial diversity, community assembly, and coexistence networks when developing strategies to manage and protect river–lake ecosystems, particularly in efforts to control cyanobacterial blooms in Lake Taihu. [ABSTRACT FROM AUTHOR]

Summary Aboveground and belowground attributes of terrestrial ecosystems interact to shape carbon (C) cycling. However, plants and soil organisms are usually studied separately, leading to a knowledge gap regarding their coordinated contributions to ecosystem C cycling. We explored whether integrated consideration of plant and nematode traits better explained soil organic C (SOC) dynamics than plant or nematode traits considered separately. Our study system was a space‐for‐time natural restoration chronosequence following agricultural abandonment in a subtropical region, with pioneer, early, mid and climax stages. We identified an integrated fast–slow trait spectrum encompassing plants and nematodes, demonstrating coordinated shifts from fast strategies in the pioneer stage to slow strategies in the climax stage, corresponding to enhanced SOC dynamics. Joint consideration of plant and nematode traits explained more variation in SOC than by either group alone. Structural equation modeling revealed that the integrated fast–slow trait spectrum influenced SOC through its regulation of microbial traits, including microbial C use efficiency and microbial biomass. Our findings confirm the pivotal role of plant‐nematode trait coordination in modulating ecosystem C cycling and highlight the value of incorporating belowground traits into biogeochemical cycling under global change scenarios. [ABSTRACT FROM AUTHOR]

Viruses constitute the most diverse and abundant biological entities on Earth. However, our understanding of this tiniest life form in complex ecosystems remains limited. Here, we recover 20,102 viral OTUs from twelve intertidal zones along the Chinese coasts. Our analysis demonstrates high viral diversity and functional potential in intertidal zones, encoding important functional genes that can be potentially transferred to microbial hosts and mediate elemental biogeochemical cycles, especially carbon, phosphate and sulfur. Virus-host abundance dynamics vary among different microbial lineages. Viral community composition is closely associated with environmental conditions, including dissolved organic matter. Concordant biogeographic patterns are observed for viruses and microbes. Viral communities are generally habitat specific with low overlaps between intertidal and other habitats. Environmental factors and geographic distance dominate the compositional variation of intertidal viromes. Overall, these findings expand our understanding of intertidal viromes within an ecological framework, providing insights into the virus-host coevolutionary arms race. The dynamic intertides, located between marine and terrestrial ecosystems, serve as a favorable habitat for exploring virus-host relationships. Here, the authors recover 20,102 viral OTUs from twelve intertidal zones along the Chinese coasts, with further analyses expanding our understanding of intertidal viromes within an ecological framework. [ABSTRACT FROM AUTHOR]

The main chemical, ecotoxicological, and environmental fate characteristics of cyanide, along with its treatment methods for cyanide-contaminated wastewater, were thoroughly examined. A global biogeochemical cycle of cyanide is proposed, covering the key physicochemical processes occurring in aqueous, soil, and atmospheric environments. The principles, advantages, and disadvantages of various treatment methods—including chemical, physicochemical, electrochemical, photochemical, and biological approaches—are evaluated. Finally, the feasibility of reusing cyanide waste is explored. [ABSTRACT FROM AUTHOR]

Wind-borne dust supply of iron (Fe) to the oceans plays a crucial role in Earth's biogeochemical cycles. Iron, a limiting micronutrient for phytoplankton growth, is fundamental in regulating ocean primary productivity and in turn the global carbon cycle. The flux of bioavailable Fe to the open ocean affects oscillations in atmospheric CO2 due to its control on inorganic carbon fixation into organic matter that is eventually exported to the sediments. However, the nature of dustdelivered Fe to the ocean and controls on its bioavailability remain poorly constrained. To evaluate the supply of wind-borne bioavailable Fe and its potential impact on Fe-based climate feedbacks over the last 120,000 years, we examine sediment profiles from four localities that define a proximal to distal transect relative to Saharan dust inputs. Bulk δ56Fe isotope compositions (average = -0.05‰) and FeT/Al ratios suggest crustal values, thus pointing to a dominant dust origin for the sediments at all four sites. We observed no variability in grain size distribution or in bioavailable Fe supply at individual sites as a function of glacial-versus-interglacial deposition. Importantly, there is no correlation between sediment grain size and Fe bioavailability. Spatial trends do, however, suggest increasing Fe bioavailability with increasing distance of atmospheric transport, and our sediments also indicate the loss of this Fe and thus potential bioavailability utilization once deposited in the ocean. Our study underscores the significance of Fe dynamics in oceanic environments using refined speciation techniques to elucidate patterns in Fe reactivity. Such insights are crucial for understanding nutrient availability and productivity in various ocean regions, including the Southern Ocean, where winddelivered Fe may play a pivotal role. It is expected that dust delivery on glacialinterglacial timescales would be more pronounced in these high-latitude regions. Our findings suggest that studies linking Fe availability to marine productivity should benefit significantly from refined Fe speciation approaches, which provide insights into the patterns and controls on Fe reactivity, including atmospheric processing. These insights are essential for understanding the impacts on primary production and thus carbon cycling in the oceans and consequences for the atmosphere. [ABSTRACT FROM AUTHOR]

Although the transfer of methane‐derived carbon (MDC) to benthic macroinvertebrates such as chironomid larvae and oligochaetes has been well documented, knowledge of the transfer of MDC to fish is limited.We investigated the MDC contribution to 28 fish species through their growth stages and examined the relationship between fish traits including body size, and MDC contribution to fish within species in Lake Kasumigaura, Japan. We used carbon stable isotope ratios and a two‐source mixing model (methane‐oxidation bacteria [MOB] and particulate organic matter) to estimate the MDC contribution to fish.The MDC contribution to individual fish ranged from 0% to 21.5%. Anguilla japonica showed the highest MDC contribution (mean 3.8%). Fish species were classified into four groups according to two criteria: (a) whether the correlation between the MDC contribution and fish size (within species) was significantly negative (negative vs. not significant; ns); and (b) whether the 90th percentile of MDC contribution was 0% or not. The mean MDC contribution was highest (2.18% ± 2.93%, 12 species) for the group with (a)ns/(b)>0%, including the high contribution species such as Abbottina rivularis (mean 5.5%) and Biwia zezera (mean 9.8%). This group (12 species) included relatively high numbers of benthic habitat use (eight species) and omnivores (nine species). The mean MDC contributions were almost zero for the group with (a)ns/(b)=0% (seven species), which included only two species of benthic habitat use and one species of omnivores. The mean MDC contributions were intermediate for the other groups with (a)negative/(b)>0% (1.30% ± 1.17%, seven species) and (a)negative/(b)=0% (0.10%, two species). The negative correlation between fish size within species and MDC contribution in groups with (a)negative/(b)>0% and (a)negative/(b)=0% indicated that ontogenetic habitat and dietary shifts induced changes in MDC transfer.Our results suggest that 21 out of 28 fish species were involved in the MDC transfer in a shallow lake, but variation in MDC transfer could be explained by fish traits (trophic guild and habitat use). Although the mean MDC contribution to all fish species was low (0.61% ± 1.97%), the roughly estimated annual consumption rate of fish on MOB corresponded to approximately 10% of the MOB production in the sediment, suggesting that fish contribute to methane dynamics from the perspective of biogeochemical cycles. [ABSTRACT FROM AUTHOR]

The decomposition of carcasses by scavengers and microbial decomposers is an important component of the biochemical cycle that can strongly alter the chemical composition of soils locally. Different scavenger guilds are assumed to have a different influence on the chemical elements that leak into the soil, although this assumption has not been empirically tested. Here, we experimentally determine how different guilds of vertebrate scavengers influence local nutrient dynamics. We performed a field experiment in which we systematically excluded different subsets of vertebrate scavengers from decomposing carcasses of fallow deer (Dama dama), and compared elemental concentrations in the soil beneath and in the vegetation next to the carcasses over time throughout the decomposition process. We used four exclusion treatments: excluding (1) no scavengers, thus allowing them all; (2) wild boar (Sus scrofa); (3) all mammals; and (4) all mammals and birds. We found that fluxes of several elements into the soil showed distinct peaks when all vertebrates were excluded. Especially, trace elements (Cu and Zn) seemed to be influenced by carcass decomposition. However, we found no differences in fluxes between partial exclusion treatments. Thus, vertebrate scavengers indeed reduce leakage of elements from carcasses into the soil, hence influencing local biochemical cycles, but did so independent of which vertebrate scavenger guild had access. Our results suggest that carcass-derived elements are dispersed over larger areas rather than locally leak into the soil when vertebrate scavengers dominate the decomposition process. [ABSTRACT FROM AUTHOR]

Quaternary unconsolidated sediments are pronouncedly widespread features on the planetary surface, documenting significant geological signals of earth surface processes, climate change and biogeochemical cycles. The extensive unconsolidated deposits play a vital role in natural hazards and Anthropogenic activities, especially in alpine regions where massive unconsolidated materials are produced. However, the spatial distribution and total volume of unconsolidated sediments across the Yarlung Tsangpo River Basin (YTRB) remain largely unknown due to the limitation of traditional field surveys and on‐site measurements as well as the complex landscape in the remote area. This study presents the datasets for the systematic distribution and spatial accumulation of unconsolidated sediments across the Yarlung Tsangpo River Basin, southern Tibet. Combining remotely sensed data with numerous field investigations, an integrated method based on image processing and kriging interpolation‐pixel integration was performed to semi‐automatically classify and quantify the unconsolidated sediments. Eleven categories of sediments were mapped and their total accumulation is estimated at approximately 4.97 × 1011 t. Ultimately, 17 groups of classification and thickness maps were derived, revealing the distribution and volume of unconsolidated and Quaternary sediments. The datasets fill the gaps in comprehensive investigations of unconsolidated sediments for YTRB, and provide a fundamental database to support the scientific understanding of potential linkages between the distribution of unconsolidated sediments with environmental changes and human activities. [ABSTRACT FROM AUTHOR]

The vertical distribution of the marine total suspended matter (TSM) concentration significantly influences marine material transport, sedimentation processes, and biogeochemical cycles. Traditional field observations are constrained by limited spatial and temporal coverage, necessitating the use of remote-sensing technology to comprehensively understand TSM variations over extensive areas and periods. This study proposes a remote-sensing approach to estimate the vertical distribution of TSM concentrations using MODIS satellite data, with the Bohai Sea and Yellow Sea (BSYS) as a case study. Extensive field measurements across various hydrological conditions and seasons enabled accurate reconstruction of in situ TSM vertical distributions from bio-optical parameters, including the attenuation coefficient, particle backscattering coefficient, particle size, and number concentration, achieving a determination coefficient of 0.90 and a mean absolute percentage error of 26.5%. In situ measurements revealed two distinct TSM vertical profile types (vertically uniform and increasing) and significant variation in TSM profiles in the BSYS. Using surface TSM concentrations, wind speed, and water depth, we developed and validated a remote-sensing approach to classify TSM vertical profile types, achieving an accuracy of 84.3%. Combining this classification with a layer-to-layer regression model, we successfully estimated TSM vertical profiles from MODIS observation. Long-term MODIS product analysis revealed significant spatiotemporal variations in TSM vertical distributions and column-integrated TSM concentrations, particularly in nearshore regions. These findings provide valuable insights for studying marine sedimentation and biological processes and offer a reference for the remote-sensing estimation of the TSM vertical distribution in other marine regions. [ABSTRACT FROM AUTHOR]

An accurate and historical land cover monitoring dataset for Alaska could provide fundamental information for a range of studies, such as conservation habitats, biogeochemical cycles, and climate systems, in this distinctive region. This research addresses challenges associated with the extraction of training data for timely and accurate land cover classifications in Alaska over longer time periods (e.g., greater than 10 years). Specifically, we designed the "Region-Specific Model Adaptation (RSMA)" method for training data. The method integrates land cover information from the National Land Cover Database (NLCD), LANDFIRE's Existing Vegetation Type (EVT), and the National Wetlands Inventory (NWI) and machine learning techniques to generate robust training samples based on the Anderson Level II classification legend. The assumption of the method is that spectral signatures vary across regions because of diverse land surface compositions; however, despite these variations, there are consistent, collective land cover characteristics that span the entire region. Building upon this assumption, this research utilized the classification power of deep learning algorithms and the generalization ability of RSMA to construct a model for the RSMA method. Additionally, we interpreted existing vegetation plot information for land cover labels as validation data to reduce inconsistency in the human interpretation. Our validation results indicate that the RSMA method improved the quality of the training data derived solely from the NLCD by approximately 30% for the overall accuracy. The validation assessment also demonstrates that the RSMA method can generate reliable training data on large scales in regions that lack sufficient reliable data. [ABSTRACT FROM AUTHOR]

ABSTRACT Aquatic macrophyte leachate is one of the autochthonous sources of carbon and nitrogen in aquatic systems, and microbial communities easily mineralize these elements. Understanding the effects of climate change on the consumption of dissolved oxygen (DO) due to the mineralization of leachate from aquatic macrophytes is fundamental for accurately establishing the oxygen balance in aquatic systems and forecasting element cycling rates. Bioassays were developed to determine the consumption of DO owing to the mineralization of carbon and nitrogen of the aquatic macrophytes leachates (Myriophyllum aquaticum, Hedychium coronarium, Salvinia auriculata, and Chara sp.) when exposed to a temperature increase of 4°C (from 21°C to 25°C). The results concerning accumulated DO were fitted to a first‐order kinetic model. At 25°C, oxygen consumption due to mineralization increased by 9.6%, whereas the chemical composition of the leachate changed oxygen consumption between 7.2 (21°C) and 9.2% (25°C). The O/C stoichiometry (oxygen consumed by oxidized carbon) indicated the compositions of the leachate, and temperatures determined the pattern of oxygen consumption. Due to the chemical composition of the leachate, the values varied by approximately 17% and were higher at 25°C (about 30%). Regardless, the increase in temperature improved the oxygen consumption of leachate mineralization. After 90 days at 25°C, the highest concentrations of remaining dissolved organic carbon occurred, suggesting the selection of microorganisms and the catabolic routes that favored the production of refractory organic compounds to the detriment of mineralization. The results indicate that knowledge of the effects of climate variations on aquatic systems is crucial for an accurate understanding of the biogeochemical cycles in these environments. [ABSTRACT FROM AUTHOR]

This study presents the development, validation and use of an approach for precise and accurate cadmium (Cd) isotopic analysis at low concentration levels using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). The MC-ICP-MS unit used was equipped with a standard sample introduction system, thus using an ICP operated under wet plasma conditions, and Faraday cup amplifiers equipped with a 1013 Ω resistor. One-column anion exchange chromatography allowed isolation of Cd with 80-99% recovery and absence of an effect of potential on-column fractionation on the isotope ratio results was demonstrated. Use of both an internal (using Ag) and an external (measured in a sample-standard bracketing sequence) standard was relied on for correction of the bias introduced by instrumental mass discrimination. A long-term precision of 0.09& (2SD) for δ114/110Cd was achieved at a Cd concentration of 10 ng mL-1. The method developed was validated by analysing NIST SRM 2711a (Montana soil) and NRC TORT-3 (Lobster hepatopancreas) reference materials, yielding results consistent with literature values. Subsequently, the method was applied to two Antarctic marine organisms Adamussium colbecki and Trematomus bernacchii, collected during both the 1990s and 2020s, to investigate its potential for identifying changes in the biogeochemical cycle of Cd over time and reveal natural or anthropogenic sources. A preferential uptake of the lighter Cd isotopes in both species was observed, indicated by negative δ114/110Cd values ranging between -0.24 and -0.09&. This finding is consistent with previous studies that have reported Cd fractionation during its uptake by marine organisms, with a preference for the lighter isotopes. No significant differences in δ114/110Cd values were observed between organs of the same species or between the same species collected in the different decades, suggesting minimal Cd isotope fractionation during internal transfer and consistent Cd sources over time. Comparison with literature data suggests that the Cd source in Antarctic biota may be predominantly of natural origin, with δ114/110Cd values indicating isotopically heavier Cd than that found in Cd-polluted areas. However, further Cd isotope ratio data from various Antarctic sample types are necessary to further evaluate the Cd sources in marine samples. [ABSTRACT FROM AUTHOR]

Summary: Crassulacean acid metabolism (CAM) leaves are characterized by nocturnal acidification and diurnal deacidification processes related with the timed actions of phosphoenolpyruvate carboxylase and Rubisco, respectively. How CAM leaves manage cytosolic proton homeostasis, particularly when facing massive diurnal proton effluxes from the vacuole, remains unclear.A 12‐phase flux balance analysis (FBA) model was constructed for a mature malic enzyme‐type CAM mesophyll cell in order to predict diel kinetics of intracellular proton fluxes.The charge‐ and proton‐balanced FBA model identified the mitochondrial phosphate carrier (PiC, Pi/H+ symport), which provides Pi to the matrix to sustain ATP biosynthesis, as a major consumer of cytosolic protons during daytime (> 50%). The delivery of Pi to the mitochondrion, co‐transported with protons, is required for oxidative phosphorylation and allows sufficient ATP to be synthesized to meet the high energy demand during CAM Phase III. Additionally, the model predicts that mitochondrial pyruvate originating from decarboxylation of malate is exclusively exported to the cytosol, probably via a pyruvate channel mechanism, to fuel gluconeogenesis. In this biochemical cycle, glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) acts as another important cytosolic proton consumer.Overall, our findings emphasize the importance of mitochondria in CAM and uncover a hitherto unappreciated role in metabolic proton homeostasis. [ABSTRACT FROM AUTHOR]

Biochar is a carbon-rich product obtained by biomass pyrolysis and is considered as a means of carbon sequestration. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC in a calcareous soil. In this study, different biochar AS, TS, PP, CS were applied to the soil at different rates (0.5, 1.0, and 1.5%) The highest increase in soil organic C content was observed in the TS treatment, while the AS treatment caused a slight increase of soil organic C. The highest MBC content was recorded in AS treatment and the lowest was observed in TS. The highest CO2-C emission was recorded in the TS treatment. In contrast, the lowest CO2-C emission was observed in the PP treatment due to its high recalcitrant C content and was attributed to a positive priming effect, stabilizing BC mineralization to improve the soil. The highest β-galactosidase enzyme activity was observed in the CS treatment and the lowest activity was observed in AS. The highest change in β-glycosidase enzyme activity was observed of PP treatment and the lowest was in AS biochar application. Thus, TS treatment is recommended to increase the organic C content of soils, and the PP biochar can be used to reduce CO2-C emission. The TS, PP, and CS can be applied to increase enzyme activities. The study clearly shows that the addition of BC to arid soils may have a high potential to improve soil enzyme activities and subsequent carbon sequestration and biochemical cycles. [ABSTRACT FROM AUTHOR]

Deep subsurface microorganisms constitute over 80 % of Earth's prokaryotic biomass and play an important role in global biogeochemical cycles. Geochemical processes driven by geothermal heating are key factors influencing their biomass and activities, yet their full breadth remains uncaptured. Here, we investigated the microbial community composition and metabolism in microbial-natural-gas-bearing aquifers at temperatures ranging from 38 to 81 °C , situated above nonmicrobial-gas- and oil-bearing sediments at temperatures exceeding 90 °C. Cultivation-based and molecular gene analyses, including radiotracer measurements, of formation water indicated variations in predominant methanogenic pathways across different temperature regimes of upper aquifers: high potential for hydrogenotrophic–methylotrophic, hydrogenotrophic, and acetoclastic methanogenesis at temperatures of 38, 51–65, and 73–81 °C , respectively. The potential for acetoclastic methanogenesis correlated with elevated acetate concentrations with increasing depth, possibly due to the decomposition of sedimentary organic matter. In addition to acetoclastic methanogenesis, in aquifers at temperatures as high as or higher than 65 °C , acetate is potentially utilized by microorganisms responsible for the dissimilatory reduction of sulfur compounds other than sulfate because of their high relative abundance at greater depths. The stable sulfur isotopic analysis of sulfur compounds in water and oil samples suggested that hydrogen sulfide, generated through the thermal decomposition of sulfur compounds in oil, migrates upward and is subsequently oxidized with iron oxides present in sediments, yielding elemental sulfur and thiosulfate. These compounds are consumed by sulfur-reducing microorganisms, possibly reflecting elevated microbial populations in aquifers at temperatures as high as or higher than 73 °C. These findings reveal previously overlooked geothermal-heat-driven geochemical and microbiological processes involved in carbon and sulfur cycling in the deep sedimentary biosphere. [ABSTRACT FROM AUTHOR]

Since the Industrial Revolution, nearly 700 Gt of carbon (GtC) have been emitted into the atmosphere as CO2 derived from human activities, of which 292 GtC remain uncontrolled. By the end of this century, the atmospheric CO2 concentration is predicted to surpass 700 ppm. The effects of this sudden carbon release on the worldwide biogeochemical cycles and balances are not yet fully understood, but global warming and climate change are undeniable, with this gas playing a starring role. Governmental policies and international agreements on emission reduction are not producing results quickly enough, and the deadline to act is running out. Biological CO2 capture is a fast-acting carbon cycle component capable of sequestering over 115 GtC annually through photosynthesis. This study analyses a hypothetical scenario in which this biological CO2 capture is artificially enhanced through the large-scale cultivation of phytoplankton in partially natural photobioreactors (PBRs). To develop this approach, the current figures of the carbon cycle have been updated, and the key aspects of phytoplankton cultivation technology have been analysed. Our results show that a global increase of 6.5% in biological capture, along with the subsequent stabilization of the produced biomass, could counteract the current CO2 emission rate and maintain atmospheric levels of this gas at their current levels. Based on a review of the available literature, an average production rate of 17 g/m2·day has been proposed for phytoplankton cultivation in horizontal PBRs. Using this value as a key reference, it is estimated that implementing a large-scale production system would require approximately 2.1 × 106 km2 of the Earth's surface. From this, a production system model is proposed, and the key technological and political challenges associated with establishing these extensive cultivation areas are discussed. [ABSTRACT FROM AUTHOR]

Biogeochemical redox cycling of iron (Fe) essentially governs various geochemical processes in nature. However, the mechanistic underpinnings of Fe-redox cycling in deep-sea sediments remain poorly understood, due to the limited access to the deep-sea environment. Here, abyssal sediment collected from a depth of 5800 m in the Pacific Ocean was characterized for its elemental, mineralogical, and biological properties. The sedimentary environment was determined to be oligotrophic with limited nutrition, yet contained a considerable amount of trace elements. Fe-redox reactions in sediment progressed through an initial lag phase, followed by a fast Fe(II) reduction and an extended period of Fe(III) oxidation before achieving equilibrium after 58 days. The presence of an external H2 electron donor significantly increased the extent of Fe(III) bio-reduction by 7.73% relative to an amendment-free control under high pressure of 58 MPa. A similar enhancement of 11.20% was observed following lactate amendment under atmospheric pressure. Fe(II) bio-oxidation occurred after 16 days' anaerobic culturing, coupled with nitrate reduction. During Fe bio-redox reactions, microbial community composition was significantly shaped by the presence/absence of an electron donor, while the hydrostatic pressure levels were the controlling factor. Shewanella spp. emerged as the primary Fe(III)-reducing microorganisms, and were stimulated by supplemented lactate. Marinobacter hydrocarbonoclasticus was the predominant Fe(II)-oxidizing microorganism across all conditions. Our findings illustrate continuous Fe-redox reactions occurring in the deep-sea environment, with coexisting Fe-redox microorganisms determining the oscillation of Fe valence states within the abyssal sediment. [ABSTRACT FROM AUTHOR]

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Background: Bacteria, Archaea, and Microeukaryotes comprise taxonomic domains that interact in mediating biogeochemical cycles in coastal waters. Many studies have revealed contrasting biogeographic patterns of community structure and assembly mechanisms in microbial communities from different domains in coastal ecosystems; however, knowledge of specific biogeographic patterns on microbial co-occurrence relationships across complex coastal environmental gradients remains limited. Using a dense sampling scheme at the regional scale, SSU rRNA gene amplicon sequencing, and network analysis, we investigated intra- and inter-domain co-occurrence relationships and network topology-based biogeographic patterns from three microbial domains in coastal waters that show environmental gradients across the inshore-nearshore-offshore continuum in the East China Sea. Results: Overall, we found the highest complexity and connectivity in the bacterial network, the highest modularity in the archaeal network, and the lowest complexity, connectivity, and modularity in the microeukaryotic network. Although microbial co-occurrence networks from the three domains showed distinct topological features, they exhibited a consistent biogeographic pattern across the inshore-nearshore-offshore continuum. Specifically, the nearshore zones with intermediate levels of terrestrial impacts reflected by multiple environmental factors (including water temperature, salinity, pH, dissolved oxygen, and nutrient-related parameters) had a higher intensity of microbial co-occurrence for all three domains. In contrast, the intensity of microbial co-occurrence was weaker in both the inshore and the offshore zones at the two ends of the environmental gradients. Archaea occupied a central position in the microbial inter-domain co-occurrence network. In particular, members of the Thaumarchaeota Marine Group I (MGI, now placed within the Family Nitrosopumilaceae of the Phylum Thermoproteota) appeared to be the hubs in the biogeographic shift between inter-domain network modules across environmental gradients. Conclusions: Our work offers new insights into microbial biogeography by integrating network features into biogeographic patterns, towards a better understanding of the potential of microbial interactions in shaping biogeographic patterns of coastal marine microbiota. [ABSTRACT FROM AUTHOR]

Global monitoring of persistent organic pollutants (POPs) has intensified following regulatory efforts aimed at reducing their release. In this context, we compiled over 10,000 POP measurements, reported from 1980 to 2023, to assess the effectiveness of these legislative measures in the global marine environments. While a general decreasing trend in legacy POP concentrations is evident across various maritime regions, highlighting the success of source control measures, the Arctic Ocean and its marginal seas have experienced a rise in POP levels. This increase suggests the northward migration of pollutants via ocean currents from mid-latitude regions to polar areas. Despite global efforts to reduce emissions, the continued transport and accumulation of pollutants to the Arctic regions may have substantial ecological impacts. Addressing these environmental challenges demands a thorough understanding of POP dynamics, including response times, multiphase transport, and biogeochemical cycling. Continued research into these processes is vital to accurately map their distribution and temporal variations within marine systems. [ABSTRACT FROM AUTHOR]

Although aboveground biodiversity has been extensively studied, the impact of nutrient enrichment on soil microbial populations remains unclear. Soil microorganisms serve as important indicators in shaping soil nutrient cycling processes and are typically sensitive to nutrient additions. For this, we employed a factorial combination design to examine the impact of nutrient additions on the composition and function of soil bacteria in a temperate steppe. Nitrogen addition promoted the growth of copiotrophic bacteria (Proteobacteria, Firmicutes, and Bacteroidota) but inhibited the growth of oligotrophic bacteria (Acidobacteria, Chloroflexi, and Verrucomicrobiota). Phosphorus addition alleviated phosphorus deficiency, resulting in a decrease in the abundance of phoD-harboring bacteria (Actinobacteria and Proteobacteria). Significant enhancement of soil bacterial alpha diversity was observed only in treatments with added phosphorus. Changes in NO3 --N, NH4 +-N, available phosphorus, and dissolved organic carbon resulting from nutrient addition may have a greater impact on microbial community structure than changes in soil pH caused by nitrogen addition. Moreover, nutrient addition may indirectly impact microbial ecological function by altering nutrient availability in the soil. In conclusion, our study suggests that soil nutrient availability, particularly available phosphorus, affects soil bacterial communities and potentially regulates the biogeochemical cycles of soil ecosystems. [ABSTRACT FROM AUTHOR]

Plant traits which vary both within and between species often drive biogeochemical cycling. Understanding the relative role of within‐ and between‐species trait variability in driving carbon cycling is essential to scaling site measurements to global carbon budgets. In seagrass meadows, carbon and nitrogen mineralization rates and associated greenhouse gas emissions are highly variable, impeding our ability to reliably predict whether meadows are net carbon sinks. Evaluating the influence of within‐ and between‐species trait variability on greenhouse gas fluxes will improve our understanding of local‐scale drivers of greenhouse gas production and consumption in seagrass meadows. To test the effects of plant traits on dissolved greenhouse gas fluxes, we performed mesocosm incubations with live, intact seagrass plants. We compared methane (CH4) and nitrous oxide (N2O) fluxes under dark and light conditions from sediments dominated by Halodule wrightii and Thalassia testudinum across dormant, early and peak growing seasons in a subtropical meadow along the west coast of peninsular Florida. We also measured oxygen (O2) fluxes to interpret greenhouse gas fluxes within the context of community metabolism. We measured several seagrass traits, such as above‐ and below‐ground biomass and leaf and root area and assessed their impact as well as the impact of species identity on dissolved gas fluxes. We found that abiotic factors linked to metabolism (i.e. light and temperature) influenced greenhouse gas fluxes across seasons. In addition to light conditions and sampling month, plant size (a composite trait variable) was a significant predictor of O2 consumption and CH4 production under dark conditions, and better predicted fluxes than individual plant traits. CH4 production was slightly higher in H. wrightii‐dominated sediments, but species identity was less important than plant size in driving CH4 production. N2O fluxes were low and not influenced by plant traits or species identity. Synthesis: Our results indicate that within‐species more so than between‐species trait variability drives the direction and magnitude of CH4 fluxes in seagrass meadows. We identified a trade‐off where seagrass biomass is often associated with enhanced sediment carbon storage, but in our study, plant size promoted CH4 production, potentially offsetting the benefits of long‐term storage. [ABSTRACT FROM AUTHOR]

Boron (B) is an essential micronutrient for plant growth and development; however, the process of B toxicity in citrus production is still poorly understood. We proposed a hypothesis that B toxicity in citrus trees is related to the characteristics of B transport from soil to leaf or fruit. For this, a field experiment was conducted for two treatments, control (B free or without B) and B fertilizer treatment (100 g Na2B4O7·10H2O plant-1), to investigate the effects on plant growth, nutrient uptake, fruit yield and quality, and B transport in 10-yearold pomelo trees [Citrus grandis (L.) Osbeck cv. Guanximiyou]. Our results showed that excess B fertilization directly led to B toxicity in pomelo trees by dramatically increasing soil total B and water-soluble B contents. B toxicity induced interveinal chlorosis in leaves and decreased leaf biomass and function, resulting in a decreased 45.3% fruit yield by reducing 30.6% fruit load and 21.4% single fruit weight. Also, B toxicity induced changes in mineral elements between leaf positions and fruit parts, in which the concentrations of B, potassium, and magnesium were increased while those of nitrogen and iron were decreased. Under B toxicity conditions, fruit quality parameters of total soluble solids (TSS), TSS/titratable acidity (TA), total soluble sugar, sucrose, pH, vitamin C, and total phenol contents decreased, which were regulated by the lower carbohydrate production in new leaves and the lower transport capacity in old leaves. Moreover, B toxicity significantly increased the transfer factor and bioconcentration factor of B in pomelo plants, with higher levels in leaf organs than in fruit organs. Taken together, excess B fertilization-induced B toxicity in pomelo trees, with induced growth inhibition and nutrient disorder, results in reduced fruit yield and quality, which are related to B transport from soil to organs. The findings of this study highlight the understanding of B toxicity in citrus plants and strengthen B management in pomelo production for high yield and high quality. [ABSTRACT FROM AUTHOR]

A new dataset from oceanographic cruises in the Western Mediterranean Sea (WMED) was compiled to integrate the previously published regional data product about dissolved inorganic nutrients CNR-DIN-WMED about dissolved inorganic nutrients (https://doi.org/10.1594/PANGAEA.904172 , Belgacem et al., 2019, 2020). The Mediterranean region is experiencing rapid changes, necessitating high-quality and reliable datasets. However, the scarcity of the in-situ observations hinders the understanding of these changes and their impact on biogeochemical cycles. Dissolved oxygen is a vital component of marine ecosystems and plays a fundamental role in governing nutrient and carbon cycles, underscoring the need for accurate and reliable data. To address this, a high resolution, regional-scale data product was developed to understand decadal variability and spatial/temporal patterns of the ventilation process in the WMED. This study presents an extensive collection of unpublished dissolved oxygen data from continuous sensors collected between 2004 and 2023, along with a description of the quality assurance procedures. The quality assurance process involves calibration of CTD measurements against Winkler analyses and the comparison of deep observations with reference datasets, using the crossover analysis. The resulting data product O2WMED can be used as reference for assessing oxygen sensors mounted on biogeochemical Argo (BGC-Argo) floats or Gliders and for regional model validation. [ABSTRACT FROM AUTHOR]

Background: Arbuscular mycorrhizas (AM) are the most widespread terrestrial symbiosis and are both a key determinant of plant health and a major contributor to ecosystem processes through their role in biogeochemical cycling. Until recently, it was assumed that the fungi which form AM comprise the subphylum Glomeromycotina (G-AMF), and our understanding of the diversity and ecosystem roles of AM is based almost exclusively on this group. However recent evidence shows that fungi which form the distinctive 'fine root endophyte' (FRE) AM morphotype are members of the subphylum Mucoromycotina (M-AMF), so that AM symbioses are actually formed by two distinct groups of fungi. Results: We investigated the influence of nitrogen (N) addition and wheat variety on the assembly of AM communities under field conditions. Visual assessment of roots showed co-occurrence of G-AMF and M-AMF, providing an opportunity to compare the responses of these two groups. Existing 'AM' 18S rRNA primers which co-amplify G-AMF and M-AMF were modified to reduce bias against Mucoromycotina, and compared against a new 'FRE' primer set which selectively amplifies Mucoromycotina. Using the AM-primers, no significant effect of either N-addition or wheat variety on G-AMF or M-AMF diversity or community composition was detected. In contrast, using the FRE-primers, N-addition was shown to reduce M-AMF diversity and altered community composition. The ASV which responded to N-addition were closely related, demonstrating a clear phylogenetic signal which was identified only by the new FRE-primers. The most abundant Mucoromycotina sequences we detected belonged to the same Endogonales clades as dominant sequences associated with FRE morphology in Australia, indicating that closely related M-AMF may be globally distributed. Conclusions: The results demonstrate the need to consider both G-AMF and M-AMF when investigating AM communities, and highlight the importance of primer choice when investigating AMF community dynamics. [ABSTRACT FROM AUTHOR]

Microbes were the only form of life on Earth for most of its history, and they still account for the vast majority of life's diversity. They convert rocks to soil, produce much of the oxygen we breathe, remediate our sewage, and sustain agriculture. Microbes are vital to planetary health as they maintain biogeochemical cycles that produce and consume major greenhouse gases and support large food webs. Modern microbiologists analyze nucleic acids, proteins, and metabolites; leverage sophisticated genetic tools, software, and bioinformatic algorithms; and process and integrate complex and heterogeneous datasets so that microbial systems may be harnessed to address contemporary challenges in health, the environment, and basic science. Here, we consider an inevitably incomplete list of emergent themes in our discipline and highlight those that we recognize as the archetypes of its modern era that aim to address the most pressing problems of the 21st century. This review explores the history of microbiology and contemplates the future of this evolving discipline as microbiologists embrace rapidly emerging technologies to explore systems of great complexity and answer fundamental questions of the modern microbiology era. [ABSTRACT FROM AUTHOR]

Background: The potential effects of global warming on soil fungal communities and their functions remain uncertain. To address this issue, we investigated the effects of 3-year simulated field warming on the community and function of fungi in a temperate steppe of Inner Mongolia, northern China. Methods: The diversity and structure of the fungal community were measured by high-throughput sequencing. The functionality of fungal communities was identified by comparison with the ITS reference database. Results: Our results showed that warming did not affect the diversity of fungi, but significantly increased the complexity of the fungal community, with fungal taxa more closely associating with each other. We observed that plant pathogens and arbuscular mycorrhizal fungi were the most abundant functional groups. Meanwhile, warming significantly decreased the relative abundance of animal pathogens. Conclusions: Warming significantly increased the complexity of the fungal community, with soil pH being the main factor affecting soil fungal function. Our findings emphasize that the response of the fungal community and its functional groups to warming has significant implications for ecosystem biogeochemical cycling. [ABSTRACT FROM AUTHOR]

Eukaryotic microorganisms were the key components of marine microecosystems and were involved in biogeochemical cycling processes. Although oceanographers have emphasized their importance in open oceans, the current understanding was not comprehensive enough about the assembly processes and co-occurrence network of different fraction eukaryotic microbial communities in the coastal China sea. We used co-occurrence networks and ecological process model to investigate possible ecological interactions in two fractions (small fraction 0.22-3 mm; large fraction 3-200 mm) of eukaryotes throughout different depths and geographical regions of coastal China sea. We found that environmental distance shapes the diversity of the two fractions eukaryotic microorganisms. Dispersal limitation and homogeneous selection processes were the key drivers of eukaryotic microbial community assembly. Co-occurrence network analysis showed that the networks of the 0.2-3 mm eukaryotes more nodes and edges, with more complex interactions between microorganisms, and higher network stability than that of 3-200 mm eukaryotic microorganisms. Temperature, oxygen, salinity, and nutrients play the crucial role in the abundance of two fractions eukaryotic microorganisms. These results crystallize the knowledge of eukaryotic microbes in the coastal China sea, which was essential for addressing the challenges posed by global change. [ABSTRACT FROM AUTHOR]

Diatoms (> 2 mm) have traditionally been identified as the primary biological agents linking the carbon (C) and silicon (Si) cycles. However, recent research has shown that picophytoplankton species (< 2 mm) also play a crucial role in the intertwined Si-C biogeochemical cycling in marine ecosystems. In this study, we examined the spatial distribution and vertical variation of micro/nano-diatoms and picophytoplankton in the eastern Indian Ocean (EIO), aimed to differentiate the contributions of living carbon and biogenic silica (bSi) stocks between diatoms and picophytoplankton. The study revealed that the abundance of picophytoplankton surpasses that of diatoms by four to seven orders of magnitude. Synechococcus was predominantly presented in the upper layer, while Prochlorococcus, picoeukaryotes, and diatoms were primarily located in the middle layer. Aggregation Boosted Tree (ABT) and Generalized Additive Models (GAM) analyses revealed that temperature and silicate (DSi) levels strongly influenced the diatom and picophytoplankton communities in the EIO. The fractions smaller than 2 mm made substantial contributions of 86.20%, 55.69%, and 96.86% to chlorophyll a (Chl-a), particulate organic carbon (POC), and living carbon biomass, respectively, underscoring the ecological significance of picophytoplankton in the carbon cycle of oligotrophic regions. Picophytoplankton represented a 33.06% of bSi stocks in the area, comparable to the contribution of diatoms (> 20 mm). Moreover, estimated contributions of diatom living carbon and silicon quota averaged 0.47% and 0.66%, respectively, while that of Synechococcus stood at 2.58% and 1.77%, indicating the predominance of Synechococcus as a weakly siliceous organism with high cell abundance in oligotrophic seas. Overall, this study draws on data from diatom and picophytoplankton biomass in the EIO to offer insights into the disproportionate carbon and silicon budgets in oligotrophic oceans from a biological perspective. [ABSTRACT FROM AUTHOR]

Iron‐rich, ferruginous waters were the dominant geochemical regime for most of Earth's history. Modern ferruginous waters are found in stratified, sulfur‐poor lakes, and serve as crucial analogs for biogeochemical cycling throughout Earth's past. Here we present the first depth‐resolved data of physical structure, nutrients and trace elements from Lake Poso (Indonesia), a deep oligotrophic ancient lake. Lake Poso is ferruginous, with anoxia below ~ 90 m depth, placing it among the world's largest ferruginous lakes. Physical stratification is weaker than other tropical anoxic lakes, indicating sensitivity for paleoclimate reconstructions. Trace elements and nutrients are predominantly shaped by the oxic–anoxic transition. Manganese– and Fe oxyhydroxide–driven biogeochemical cycling occurs at distinct depth horizons, with Co and Ni controlled by Mn and showing shallow release in anoxic waters, while V, Cr, P, and As are controlled by Fe, with release in surface sediments and diffusive transport. Chromium is nonquantitatively removed in anoxic waters, in contrast to widespread assumptions in Cr‐based paleoreconstructions. Oxycline U and Se removal corresponds to a local N minimum, suggesting biological reduction and/or uptake. These first ferruginous water Se data also show removal in sediments, indicating sediment signals reflect multiple removal processes and informing Se‐based paleoreconstructions, while the absence of sediment U removal contrasts other anoxic basins. A comparison with other ferruginous lakes demonstrates how local influences drive deviations from expectations in other systems, and highlight common, generalizable ferruginous basin features. Therefore, these data will guide research in ferruginous settings across space and time, and improve paleoreconstructions from ferruginous sediment records. [ABSTRACT FROM AUTHOR]

Seafloor hydrothermal venting may be an important source of marine Cu and affect the biogeochemical cycling of Cu in the oceans. The distribution of Cu and its isotope compositions (δ65Cu) can provide insight into seafloor hydrothermal processes and their role in the mass balance of global Cu. To date, there are no published Cu isotope data for hydrothermal plumes and very few reports on Cu concentration distributions. This study presents both Cu concentrations and dissolved Cu isotope (δ65Cu) in hydrothermal plumes from back-arc volcanoes in the Northeast Lau Basin. The dissolved Cu (dCu) concentrations range from 2.14 to 5.66 nM most of which are higher than the deep seawater concentrations. However, the concentrations for some plume samples were lower than the deep seawater dCu concentrations due to adsorption onto particles in the plumes. The δ65Cu of hydrothermal plumes vary from 0.25 to 1.05 ‰. As plumes dispersed, the Cu isotopes from high-temperature Mata Fitu and Mata Ua vents shifted towards light values. In contrast, the δ65Cu in plumes from low-temperature East Mata and West Mata vents show increasingly higher values with plume dispersal. Rayleigh distillation models are built based on the adsorption of dCu onto Fe particles and complexation with organic ligands to describe the dCu isotope evolution in hydrothermal plumes. The results suggest that the adsorption and organic complexation may be the likely explanations for the observed dCu isotope compositions in plumes from high- and low-temperature venting, separately, besides the mixing with background seawater. Our measured δ65Cu in three fluid samples (0.08, 0.09 and 0.20 ‰) are lower than that of the characterized sinks (∼0.3 ‰) in the oceans, indicating that hydrothermal fluids might be a source of light Cu isotopes. However, the δ65Cu (0.53 ‰ on average) in plume samples are higher than 0.3 ‰ and these seafloor hydrothermal plumes do not seem to be a source of light Cu isotope of dCu, at least near the venting sites. Our study first reveals the Cu isotope compositions and evolution in hydrothermal plumes and provides new hints about the impact of seafloor hydrothermal venting on the modern oceanic Cu isotope budget. [ABSTRACT FROM AUTHOR]

Summary: Mycorrhizal associations are key mutualisms that shape the structure of forest communities and multiple ecosystem functions. However, we lack a framework for predicting the varying dominance of distinct mycorrhizal associations in an integrated proxy of multifunctionality across ecosystems.Here, we used the datasets containing diversity of mycorrhizal associations and 18 ecosystem processes related to supporting, provisioning, and regulating services to examine how the dominance of ectomycorrhiza (EcM) associations affects ecosystem multifunctionality in subtropical mountain forests in Southwest China. Meanwhile, we synthesized the prevalence of EcM‐dominant effects on ecosystem functioning in forest biomes.Our results demonstrated that elevation significantly modified the distributions of EcM trees and fungal dominance, which in turn influenced multiple functions simultaneously. Multifunctionality increased with increasing proportion of EcM associations, supporting the ectomycorrhizal‐dominance hypothesis. Meanwhile, we observed that the impacts of EcM dominance on individual ecosystem functions exhibited different relationships among forest biomes.Our findings highlight the importance of ectomycorrhizal dominance in regulating multifunctionality in subtropical forests. However, this ectomycorrhizal feedback in shaping ecosystem functions cannot necessarily be generalized across forests. Therefore, we argue that the predictions for ecosystem multifunctionality in response to the shifts of mycorrhizal composition could vary across space and time. [ABSTRACT FROM AUTHOR]

Wildfires are among the most influential disturbances affecting ecosystem structure and biogeochemical cycles in Siberia. Therefore, accurate fire modeling via dynamic global vegetation models is important for predicting greenhouse gas emissions and other biomass-burning emissions to understand changes in biogeochemical cycles. We integrated the widely used SPread and InTensity of FIRE (SPITFIRE) fire module into the spatially explicit individual-based dynamic global vegetation model (SEIB-DGVM) to improve the accuracy of fire predictions and then simulated future fire regimes to better understand their impacts. The model can reproduce the spatiotemporal variation in biomass, fire intensity, and fire-related emissions well compared to the recent satellite-based estimations: aboveground biomass (R2=0.847 , RMSE = 18.3 Mg ha -1), burned fraction (R2=0.75 , RMSE =0.01), burned area (R2=0.609 , RMSE =690 ha), dry-matter emissions (R2=0.624 , RMSE =0.01 kg DM m -2 ; dry matter), and CO 2 emissions (R2=0.705 , RMSE =6.79 Tg). We then predicted that all of the 33 fire-related gas and aerosol emissions would increase in the future due to the enhanced amount of litter as fuel load from increasing forest biomass production under climate forcing of four Representative Concentration Pathways: RCP8.5, RCP6.0, RCP4.5, and RCP2.6. The simulation under RCP8.5 showed that the CO 2 , CO, PM 2.5 , total particulate matter (TPM), and total particulate carbon (TPC) emissions in Siberia in the present period (2000–2020) will increase relatively by 189.66±6.55 , 15.18±0.52 , 2.47±0.09 , 1.87±0.06 , and 1.30±0.04 Tg species yr -1 , respectively, in the future period (2081–2100) and the number of burned trees will increase by 100 %, resulting in a 385.19±40.4 g C m -2 yr -1 loss of net primary production (NPP). Another key finding is that the higher litter moisture by higher precipitation would relatively suppress the increment of fire-related emissions; thus the simulation under RCP8.5 showed the lowest emissions among RCPs. Our study offers insights into future fire regimes and development strategies for enhancing regional resilience and for mitigating the broader environmental consequences of fire activity in Siberia. [ABSTRACT FROM AUTHOR]

Marine sediments host heterogeneous protist communities consisting of both living benthic microorganisms and planktonic resting stages. Despite their key functions in marine ecosystem processes and biogeochemical cycles, their structure and dynamics are largely unknown. In the present study, with a spatially intensive sampling design we investigated benthic protist diversity and function of surface sediment samples from three subregions of the Mediterranean Sea, through an environmental DNA metabarcoding approach targeting the 18S V4 region of rRNA gene. Protists were characterized at the taxonomic level and trophic function, both in terms of alpha diversity and community composition, testing for potential differences among marine subregions and bathymetric groups. Overall, Alveolata and Stramenopiles were the two divisions that dominated the communities. These dominant groups exhibited significant differences among the three Mediterranean subregions in the alpha diversity estimates based on the detected ASVs, for all computed indices (ASV richness, Shannon and Simpson indices). Protist communities were also found to be significantly different in terms of composition at the order rank in the three subregions p-value < 0.01). These differences were mainly driven by Anoecales, Peridiniales, Borokales, Paraliales and Gonyaulacales, which together contributed almost 80% of the average dissimilarity. Anoecales was the dominant order in the Ionian – Central Mediterranean and Adriatic Sea, but with considerably different relative abundances (52% and 36%, respectively), while Borokales was the dominant order in the Western Mediterranean Sea (33%). Similarly, significant differences among the three marine subregions were also highlighted when protist assemblages were examined in terms of trophic function, both in terms of alpha diversity (calculated on the ASVs for each trophic group) and community composition p-value < 0.01. In particular, the Adriatic Sea stood out for having the highest relative abundance of autotrophic/ mixotrophic components in the surface sediments analyzed. Conversely, no significant differences in protist assemblages were found among depth groups. This study provided new insights into the taxonomic and trophic composition of benthic protist communities found in Mediterranean surface sediments, revealing geographical differences among regional seas. The results were discussed in relation to the Mediterranean environmental features that could generate the differences among benthic protist communities. [ABSTRACT FROM AUTHOR]

The 72‐foot sailing yacht Eugen Seibold is a new research platform for contamination‐free sampling of the water column and atmosphere for biological, chemical, and physical properties, and the exchange processes between the two realms. Ultimate goal of the project is a better understanding of the modern and past ocean and climate. Operations started in 2019 in the Northeast Atlantic, and will focus on the Tropical Eastern Pacific from 2023 until 2025. Laboratories for air and seawater analyses are equipped with down‐sized and automated state‐of‐the‐art technology for a comprehensive description of the marine carbon system including CO2 concentration in the air and sea surface, pH, macro‐, and micro‐nutrient concentration (e.g., Fe, Cd), trace metals, and calcareous plankton. Air samples are obtained from ca. 13 m above sea surface and analyzed for particles (incl. black carbon and aerosols) and greenhouse gases. Plankton nets and seawater probes are deployed over the custom‐made A‐frame at the stern of the boat. Near Real‐Time Transfer of underway data via satellite connection allows dynamic expedition planning to maximize gain of information. Data and samples are analyzed in collaboration with the international expert research community. Quality controlled data are published for open access. The entire suite of data facilitates refined proxy calibration of paleoceanographic and paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameters. Plain Language Summary: The new research sailing yacht Eugen Seibold (ES) enables clean, contamination‐free sampling of air and seawater to better understand the interactions between ocean and climate. For example, the oceans remove increasingly less carbon dioxide (CO2) from the atmosphere the more saturated they are with CO2 (ocean acidification). However, a detailed systematic understanding of air‐sea exchange processes remains to be developed. We analyze air and seawater as well as the exchange of greenhouse gases and other substances such as aerosols and soot (black carbon) between air and seawater at high resolution using modern materials and technologies. Scaled‐down, energy‐efficient, and automated probes developed over the past decade are being used to measure around 50 different characteristics of the marine environment. The work deck at the stern of the boat allows the use of custom‐made water samplers and plankton nets to study the ocean to below 1,000 m depth. In addition, the new data enables a better understanding of past ocean archives, such as the marine plankton accumulated in seafloor sediments, to reconstruct past climate changes. From 2019 to 2022, the S/Y ES sailed in the eastern North Atlantic and will operate in the tropical eastern Pacific until 2025. Key Points: New research platform for contamination‐free sampling of the water column and atmosphere of biological, chemical, and physical propertiesComprehensive marine geochemical analyzes including carbon (e.g., CO2) in air and sea surfaceProxy calibration of paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameters [ABSTRACT FROM AUTHOR]

Our oceans are populated with a wide diversity of planktonic organisms that form complex dynamic communities at the base of marine trophic networks. Within such communities are phytoplankton, unicellular photosynthetic taxa that provide an estimated half of global primary production and support biogeochemical cycles, along with other essential ecosystem services. One of the major challenges for microbial ecologists has been to try to make sense of this complexity. While phytoplankton distributions can be well explained by abiotic factors such as temperature and nutrient availability, there is increasing evidence that their ecological roles are tightly linked to their metabolic interactions with other plankton members through complex mechanisms (e.g. competition and symbiosis). Therefore, unravelling phytoplankton metabolic interactions is the key for inferring their dependency on, or antagonism with, other taxa and better integrating them into the context of carbon and nutrient fluxes in marine trophic networks. In this review, we attempt to summarize the current knowledge brought by ecophysiology, organismal imaging, in silico predictions and co-occurrence networks using 'omics data, highlighting successful combinations of approaches that may be helpful for future investigations of phytoplankton metabolic interactions within their complex communities. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'. [ABSTRACT FROM AUTHOR]

Marine plankton communities form intricate networks of interacting organisms at the base of the food chain, and play a central role in regulating ocean biogeochemical cycles and climate. However, predicting plankton community shifts in response to climate change remains challenging. While species distribution models are valuable tools for predicting changes in species biogeography under climate change scenarios, they generally overlook the key role of biotic interactions, which can significantly shape ecological processes and ecosystem responses. Here, we introduce a novel statistical framework, association distribution modelling (ADM), designed to model and predict ecological associations distribution in space and time. Applied on a Tara Oceans genome-resolved metagenomics dataset, the present-day biogeography of ADM-inferred marine plankton associations revealed four major biogeographic biomes organized along a latitudinal gradient. We predicted the evolution of these biome-specific communities in response to a climate change scenario, highlighting differential responses to environmental change. Finally, we explored the functional potential of impacted plankton communities, focusing on carbon fixation, outlining the predicted evolution of its geographical distribution and implications for ecosystem function. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'. [ABSTRACT FROM AUTHOR]

Bacteria play a crucial role in pollutant degradation, biogeochemical cycling, and energy flow within river ecosystems. However, the underlying mechanisms governing bacterial community assembly and their response to environmental factors at seasonal scales in subtropical rivers remain poorly understood. In this study, we conducted 16S rRNA gene amplicon sequencing on water samples from the Liuxi River to investigate the composition, assembly processes, and co-occurrence relationships of bacterial communities during the wet season and dry season. The results demonstrated that seasonal differences in hydrochemistry significantly influenced the composition of bacterial communities. A more heterogeneous community structure and increased alpha diversity were observed during the dry season. Water temperature emerged as the primary driver for seasonal changes in bacterial communities. Dispersal limitation predominantly governed community assembly, however, during the dry season, its contribution increased due to decreased immigration rates. Co-occurrence network analysis reveals that mutualism played a prevailing role in shaping bacterial community structure. Compared to the wet season, the network of bacterial communities exhibited higher modularity, competition, and keystone species during the dry season, resulting in a more stable community structure. Although keystone species displayed distinct seasonal variations, Proteobacteria and Actinobacteria were consistently abundant keystone species maintaining network structure in both seasons. Our findings provide insights into how bacterial communities respond to seasonal environmental changes, uncovering underlying mechanisms governing community assembly in subtropical rivers, which are crucial for the effective management and conservation of riverine ecosystems. [ABSTRACT FROM AUTHOR]