Terrestrial Environments Research Articles

Distribution of 3-hydroxy fatty acids in South China Sea since the last deglaciation: Applicability of 3-hydroxy fatty acid-based palaeothermometry

3-Hydroxy fatty acids (3-OH-FAs) are biomarkers for Gram-negative bacteria. Recent research has suggested that they could serve as temperature proxies in both terrestrial and marine environments, based on calibrations using modern samples. However, these proxies have been only applied in a speleothem for the Holocene and a short sediment core in the East China Sea for past 58 years, thus more evidence is needed to testify their validity. In this study, we analyzed the distribution of 3-OH-FAs in a sediment core from the northern South China Sea (SCS) spanning the past 19 thousand years (19 ka). We detected 3-OH-FAs, including normal (n-), iso (i-), and anteiso (a-) isomers, in all 56 samples with carbon numbers ranging from 10 to 18. The distribution of 3-OH-FAs in marine sediments differed from that in terrestrial sediments (soil, stalagmite, and lake sediments), with a higher fractional abundance of anteiso-FAs. Two temperature proxies, RANs and RAN13, showed a positive correlation (R2 = 0.5; p < 0.001), with RANs-SST being closer to the actual sea surface temperature (SST). The reconstructed RANs-SST in our core exhibited a typical glacial-Holocene increase of 2–3 °C (20.8 ± 2.7 °C vs. 24.1 ± 1.3 °C). Several abrupt climate events, such as the Younger Dryas, BØlling/AllerØd, and Heinrich Event 1, were also recorded in RANs-SST. Therefore, our study supports the applicability of 3-OH-FA RANs as a temperature proxy for paleoenvironmental reconstructions, at least in the last glacial periods.

Culturable Streptomyces spp. from high-altitude, oligotrophic North Western Himalaya: a comprehensive study on the diversity, bioactivity and insights into the proteome of potential species.

The increasing global concern of antimicrobial resistance and shortage of new antimicrobials necessitates exploring untapped terrestrial environments for new bioactive microbiome diversity. The low-temperature and oligotrophic North Western Himalaya (NWH) region has a vast diversity of Streptomyces with potential antimicrobial properties that remain largely unexplored. This study evaluates the diversity of culturable Streptomyces from high-altitude NWH and their potential as a source of new antimicrobials through genus-specific isolation and identification. The results demonstrate a distinct phylogenetic clustering of Streptomyces from different sampling regions of NWH, site-specific variation in culturable β-diversity and species commonness with varying intersite bioactivity among different sites. Further, the study optimized the media selection for large-scale culture cultivation in antibiotic production processes and demonstrated the antimicrobial efficacy of Streptomyces against a range of pathogens through in vitro bioassays using minimum inhibitory concentration determination and antibiofilm activity. Untargeted label-free proteomic profiling also revealed variable expression of stress-response proteins and antibiotic regulators as a competitive survival strategy for selective antagonistic Streptomyces. The findings highlight the potential of NWH in augmenting antimicrobial discovery and combating antimicrobial resistance through the isolation and study of novel bioactive Streptomyces.

Cradle-to-gate life cycle assessment of Spirulina bioplastic produced via plasticization with glycerol

Bioplastics have been used as alternatives to conventional petroleum-based plastics to lessen the burdens on marine and terrestrial environments due to their non-biodegradability and toxicity. However, recent studies have shown that not all bioplastics may be environmentally friendly. Microalgae, such as Spirulina that do not require arable land, have been identified as a potential bioplastic source. In this study, cradle-to-gate life cycle assessment (LCA) was carried out in openLCA program using the Agribalyse database, to evaluate the environmental impacts of Spirulina bioplastic, formed from plasticization of Spirulina powder with glycerol. Two processes were created for the inventories of (i) Spirulina powder and (ii) Spirulina bioplastic, where the output of the former served as an input for the latter. The extruded bioplastic sheets were food-grade and could be used as edible packaging materials. The bioplastic was also compared to conventional plastics and it was found that the energy consumption was 3.83 ± 0.26 MJ/kg-bioplastic, which was 12% and 22% higher than that of LDPE and PVC plastic films, respectively. The impacts on the environment showed that the chemical growth medium (Zarrouk medium) and electricity were the main contributors in most of the categories. Compared to the PVC and LDPE films, the Spirulina bioplastic's impacts on the aquatic ecosystems were 2–3 times higher. The global warming potential of the Spirulina bioplastic was 1.99 ± 0.014 kg CO2 eq, which was 23% and 47% lower than that of LDPE and PVC films, respectively. Sensitivity analysis was carried out by changing the electricity source and using alternative growth media. Except for the case of switching to solar energy, the results for other cases did not differ significantly from the base case scenario. Future studies were suggested to identify different greener alternatives to the growth medium as well as different energy mixes for more environmentally benign solutions.

Morphological variation, modularity and integration in the scapula and humerus of Lissotriton newts.

The modular organization of tetrapod paired limbs and girdles, influenced by the expression of Hox genes is one of the primary driving forces of the evolution of animal locomotion. The increased morphological diversification of the paired limbs is correlated with reduced between-limb covariation, while correlation within the elements is usually higher than between the elements. The tailed amphibians, such as Lissotriton newts, have a biphasic lifestyle with aquatic and terrestrial environments imposing different constraints on limb skeleton. By employing the methods of computerized microtomography and 3D geometric morphometrics, we explored the pattern of morphological variation, disparity, modularity and morphological integration in the proximal parts of the anterior limbs of six species of Eurasian small bodied newts. Although the species significantly differ in limb shape, there is a great overlap in morphology of scapula and humerus, and there are no differences in morphological disparity. For the scapula, the shape differences related to the duration of the aquatic period are in length, depth and curvature. The shape of the humerus is not affected by the length of aquatic period, and shape differences between the species are related to robustness of the body. The length of aquatic period has statistically supported phylogenetic signal. The scapula and humerus are structures of varying modularity. For the humerus, the strongest support on the phylogenetic level was for the capitulum/shaft hypothesis, which can also be interpreted as functional modularity. For the scapula, the greatest support was for the antero-posterior hypothesis of modularity in case of Lissotriton vulgaris, which can be explained by different functional roles and muscle insertion patterns, while there was no phylogenetic modularity. The modularity patterns seem to correspond with the general tetrapod pattern, with modularity being more pronounced in the distal structure. The future research should include more salamandrid taxa with different habitat preferences and both adult and larval stages, in order to explore how size, phylogeny and ecology affect the morphology and covariation patterns of limbs.

Arboreal or terrestrial: Oviposition site of Zhangixalus frogs affects the thermal function of foam nests.

Temperature is essential for the survival and development of eggs. Some anurans have evolved and developed foam nesting traits, with thermal insulation considered to be among their functions. Foam-nesting frogs tend to exhibit reproductive plasticity. For example, they oviposit on both trees and the ground. How such plasticity affects foam nest function is of major relevance and is likely related to the adaptation of foam nesting frogs. However, this has not been well studied. In this study, we examined the interaction between foam nest site, foam nest function, and egg fate using the Japanese green tree frog, Zhangixalus arboreus, and analysed how nest site differences (arboreal or terrestrial) affect the thermal function of foam nests. We compared the thermal functions of foam nests between arboreal and terrestrial oviposition sites of Z. arboreus. We artificially replaced half of the arboreal nests with terrestrial environments and recorded temperature in and outside of the experimental terrestrial nest and original arboreal nests. We also examined egg survival and hatching rates for all the nests. The results indicated superior heat insulation in terrestrial nests, with warmer temperatures inside than outside the nests, especially at night, which led to a high egg survival rate. Therefore, terrestrial ovipositing should be valid under cold weather conditions. This may be related to the evolutionary history of oviposition site plasticity of this genus, which originally had an arboreal oviposition trait but evolved into terrestrial site use owing to global cooling. Our novel insights into the evolution and adaptivity of foam nesting and oviposition site use in Z. arboreus make an important contribution to animal ecology.

Generic qPCR assays for quality control in environmental DNA research

AbstractEnvironmental DNA (eDNA) has been widely used for species surveillance. However, the lack of adequate quality control in many eDNA research projects and applications can lead to false‐negative results, greatly affecting biosecurity surveillance and conservation efforts. Exogenous DNA is routinely added to eDNA samples and used as a positive control, typically after DNA extraction. However, this type of positive control is only able to identify false negatives due to errors at the amplification stage. Therefore, errors in upstream processes, such as sample collection will not be identified by an exogenous control. We designed two independent sets of generic quality control qPCR assays (QCqPCR) targeting abundant endogenous DNA that is obtained during sample collection. Our QCqPCR assays target the chloroplast 16S and 23S ribosomal RNA sequences. In silico analyses indicated these regions were highly conserved among plants, algae and bacteria commonly found in freshwater, marine, or terrestrial environments. These QCqPCR assays were purposely mismatched against the human genome to avoid false positives resulting from human DNA contamination. Both assays remained highly efficient and sensitive under annealing temperatures between 58 and 62°C, allowing them to be multiplexed with most qPCR analyses. We validated our assays by multiplexing with a species‐specific Murray cod (Maccullochella peelii) assay on field‐collected environmental water samples. Potential false‐negative reactions can be identified by the failed or suppressed QCqPCR assay and the negative species‐specific assay. We recommend incorporating either one of the QCqPCR assays in qPCR‐based eDNA analysis to identify potential false negatives and improve the reliability of eDNA surveys.

Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe–Br inclusions and the description of a new stilbonematine genus

Abstract Nematodes are one of the most widespread and abundant animal taxa across aquatic and terrestrial environments. In marine shallow-water, porous sediments, members of the subfamily Stilbonematinae may be found in high numbers. Stilbonematinae are characterized by their coat of symbiotic bacteria, which give the nematodes a white appearance, while the nematodes themselves are usually colourless. We identified several species of the genus Robbea (Desmodoridae: Stilbonematinae) in which live specimens had a conspicuous dark purple coloration of the glandular sense organs (GSOs), highly specialized epidermal glands that are prominent in the Stilbonematinae. The dark inclusions in the GSOs of Robbea contained high concentrations of iron and bromide, regardless of their habitat. Morphological and phylogenetic analyses show that the genus Robbea is paraphyletic and we define the new genus Cyathorobbea gen. nov. for species with sucker-shaped post-pharyngeal supplements in males. Furthermore, we describe five new Robbea species from around the world. Some Robbea species are morphologically very similar and required the use of principal component analysis of morphometric data to untangle the diversity in this taxon. Our work emphasizes the value of live animal observations that enable the identification of important characters and highlights the overlooked diversity within the Stilbonematinae.

Hatching plasticity is associated with a more advanced stage at hatching in an Ambystoma with terrestrial eggs.

Hatching plasticity allows animals to initiate hatching in response to environmental cues including predation, flooding, and hypoxia. In species with terrestrial eggs but aquatic larvae, hatching plasticity often manifests as extended development of embryos when water is not available. Although these effects are taxonomically widespread, little attention has focused on differences in plasticity across closely related species with terrestrial and aquatic embryos. We propose that the terrestrial embryonic environment favors slower and prolonged development and, consequently, that we should see differences in development between closely related species that differ in where they lay their eggs. We test this hypothesis by comparing embryonic development between two mole salamanders, Ambystoma opacum and A. annulatum. Most Ambystoma lay eggs submerged in ponds but A. opacum lays its eggs on land, where hatching is triggered when eggs are submerged by rising pond levels. Embryos of both species were reared under common laboratory conditions simulating both aquatic and terrestrial nest sites. Consistent with our hypothesis, we found that A. opacum embryos exhibited slower development and took longer to hatch than A. annulatum embryos in both rearing environments. Furthermore, we observed in A. opacum a plasticity in hatching stage that was absent in A. annulatum. Our results indicate that the terrestrial-laying A. opacum has evolved slower and prolonged development relative to its aquatic-laying congener and suggest that embryonic survival in the unpredictable terrestrial environment may be facilitated by developmental plasticity.

Adaptive evolution of chloroplast division mechanisms during plant terrestrialization

Despite extensive research, the origin and evolution of the chloroplast division machinery remain unclear. Here, we employ recently sequenced genomes and transcriptomes of Archaeplastida clades to identify the core components of chloroplast division and reconstruct their evolutionary histories, respectively. Our findings show that complete division ring structures emerged in Charophytes. We find that Glaucophytes experienced strong selection pressure, generating diverse variants adapted to the changing terrestrial environments. By integrating the functions of chloroplast division genes (CDGs) annotated in a workflow developed using large-scale multi-omics data, we further show that dispersed duplications acquire more species-specific functions under stronger selection pressures. Notably, PARC6, a dispersed duplicate CDG, regulates leaf color and plant growth in Solanum lycopersicum, demonstrating neofunctionalization. Our findings provide an integrated perspective on the functional evolution of chloroplast division machinery and highlight the potential of dispersed duplicate genes as the primary source of adaptive evolution of chloroplast division.

Multiple stressors mediate the effects of warming on leaf decomposition in a large regulated river

AbstractPredicting how increasing temperatures interact with other global change drivers to influence the structure and dynamics of Earth's ecosystems is a primary challenge in ecology. Our study made use of multiple simultaneous “natural experiments” to examine how rapid warming, declining nutrients, invasive consumers, and riparian invasive species management interact to influence leaf decomposition in a large and regulated river. Specifically, we compared the breakdown of cottonwood (Populus fremontii), willow (Salix exigua), and saltcedar (Tamarix sp.) leaf litter in 2022 to a previous experiment from 1998 that occurred under much cooler water temperatures, and had higher water phosphorus concentrations, low numbers of invasive New Zealand mudsnails (Potamopyrgus antipodarum), and unaltered litter chemistry from the herbivory of saltcedar leaf beetles (Diorhabda carinulata). We found that the effects of up to 10°C warmer temperatures on leaf decomposition were mediated by the establishment and management of invasive species and declining water nutrient concentrations arising from upstream reservoir lowering. Such interactions led to accelerated breakdown of saltcedar, but relatively minor effects of warming on the rate of cottonwood and willow decomposition. Additionally, our results demonstrate the potential for favorable invasive species management outcomes in the terrestrial environment to produce unintended responses in adjacent freshwater ecosystems. As temperatures continue to rise, it is critical that future studies consider how warming interacts with multiple stressors and environmental factors to influence processes such as decomposition in freshwater ecosystems.

Diving into the Water: Amphibious Plants as a Model for Investigating Plant Adaptations to Aquatic Environments.

Amphibious plants can grow and survive in both aquatic and terrestrial environments. This review explores the diverse adaptations that enable them to thrive in such contrasting habitats. Plants with amphibious lifestyles possess fascinating traits, and their phenotypic plasticity plays an important role in adaptations. Heterophylly, the ability to produce different leaf forms, is one such trait, with submerged leaves generally being longer, narrower, and thinner than aerial leaves. In addition to drastic changes in leaf contours, amphibious plants display significant anatomical and physiological changes, including a reduction in stomatal number and cuticle thickness and changes in photosynthesis mode. This review summarizes and compares the regulatory mechanisms and evolutionary origins of amphibious plants based on molecular biology studies actively conducted in recent years using novel model amphibious plant species. Studying amphibious plants will enhance our understanding of plant adaptations to aquatic environments.

Ontogenetic Expression of Aquaporins in the Kidney and Urinary Bladder of the Japanese Tree Frog, Dryophytes japonicus.

For adult anuran amphibians, the kidney and urinary bladder play important osmoregulatory roles through water reabsorption. In the present study, we have examined ontogenetic expression of aquaporins, i.e., AQP2, AQPamU (AQP6ub, AQPa2U), and AQP3, in these organs using the Japanese tree frog, Dryophytes japonicus. Immunohistochemistry using the metamorphosing larvae at stages 40-43 localized AQP2 protein to the collecting ducts in the dorsal zone of the mesonephric kidney. At prometamorphic stages 40 and 41, labelling of AQP2 protein was observed in the apical/ subapical regions of the collecting duct cells. At climax stages 42 and 43, labels for AQP2 and AQP3 became observed in the apical/subapical regions and basolateral membrane of the collecting duct cells, respectively, as seen in the adults. As for the urinary bladder, immuno-positive labels for AQPamU were localized to the apical/subapical regions of granular cells in the mucosal epithelium at stages 40-43. On the other hand, AQP3 immunoreactivity was hardly observed in the urinary bladder at stage 40, and weakly appeared in many granular cells at stage 41. Thereafter, labels for AQP3 became evident along the basolateral membrane of granular cells at stages 42 and 43, together with AQPamU in the apical/subapical regions. These results suggest that the kidney and urinary bladder might be capable of water reabsorption, via AQP2, AQPamU, and AQP3, at stage 42, contributing to the acclimation of the tree frogs to terrestrial environments.

First palynological results from Spila nad Procjepom cave, Mljet island (Croatia)

This paper presents the first results of palynological research from the Spila nad Procjepom cave, situated in the Mljet National Park, Croatia. The palynological data obtained, enables a partial insight into the local vegetation cover, temporal changes in the vegetation during the accumulation of studied deposits (at ca. 3500 cal years BP), and post-depositional processes that influenced the palynomorph assemblage. Results of palynofacies analysis indicate changes from fluvial (channel deposits), through palustrine to terrestrial environments. Although the interpretation of changes in plant cover, due to the lack of statistical significance, should be taken with caution, preserved pollen types confirm the dominance of the Mediterranean evergreen forest vegetation on Mljet island. Moreover, a high proportion of non-arboreal pollen (NAP) indicates some level of forest degradation, ranging from Mediterranean open forest to degraded maquis. Abundant charcoal additionaly confirms that the cave was inhabited by humans.

Evaluation of heavy metals contamination in Rabbit Fish (Signus Sutor) from selected landing sites in Zanzibar, Tanzania

The increase of heavy metals concentrations in aquatic and terrestrial environments and their toxicity is of global concern. The bioaccumulation of toxic metals in fish poses a serious risk to human health when consumed. This study assessed the quality of Rabbit fish (Signus Sutor) and their associated health risks from four landing sites (namely Malindi, Mazizini, Kizimkazi and Matemwe) in Zanzibar. The concentrations of toxic metals, including Lead (Pb), Cadmium (Cd), Copper (Cu), Chromium (Cr), Nickel (Ni), and Arsenic (As), in the fish muscle were scrutinized using inductively coupled plasma optical emission spectrometry (ICP-OES). The detected mean concentration (mg/kg) of Pb, As, Cr, Cd, Cu, and Ni at Malindi were 0.25±0.14, 2.22±0.44, 0.02±0.02, 0.01±0.00, 0.02±0.02 and 0.00±0.00 respectively; at Kizimkazi were 0.39±0.39, 2.30±0.44, 0.11±0.01, 0.07±0.04, 0.17±0.13 and 0.15±0.04 respectively: at Matemwe were 0.38±0.12, 0.52±0.14, 0.04±0.02, 0.05±0.01, 0.65±0.21 and 0.09±0.03 respectively; and Mazizini were 0.21±0.12, 5.56±1.37, 0.02±0.02, 0.03±0.01, 0.05±0.02 and 0.15±0.05 respectively. The mean concentration levels detected for all the elements in the fish gathered from all four landing sites were below international and local maximum (FAO/WHO) permissible limits for human consumption, except for Arsenic (As) and lead (Pb). The study also investigated the relationship between fish size and metal concentration which shows a positive correlation for Cu and Ni. However, it was negative for the remaining metals, possibly due to ecological and metabolic differences. The study emphasizes the necessity for regular monitoring of the marine environment and enforcement of hygienic regulations, as well as the treatment of land-based pollutants before they are discharged into the marine environment to protect fish quality.

Identification of bacterial dissimilatory antimonate reductase AnrA: genes and proteins involved in antimonate respiration and resistance in Geobacter sp. strain SVR.

Geobacter sp. strain SVR uses antimonate [Sb(V)] as a terminal electron acceptor for anaerobic respiration. Here, we visualized a possible key enzyme, periplasmic Sb(V) reductase (Anr), via active staining and non-denaturing gel electrophoresis. Liquid chromatography-tandem mass spectrometry analysis revealed that a novel dimethyl sulfoxide (DMSO) reductase family protein, WP_173201954.1, is involved in Anr. This protein was closely related with AnrA, a protein suggested to be the catalytic subunit of a respiratory Sb(V) reductase in Desulfuribacillus stibiiarsenatis. The anr genes of strain SVR (anrXSRBAD) formed an operon-like structure, and their transcription was upregulated under Sb(V)-respiring conditions. The expression of anrA gene was induced by more than 1 µM of antimonite [Sb(III)]; however, arsenite [As(III)] did not induce the expression of anrA gene. Tandem mass tag-based proteomic analysis revealed that, in addition to Anr proteins, proteins in the following categories were upregulated under Sb(V)-respiring conditions: (i) Sb(III) efflux systems such as Ant and Ars; (ii) antioxidizing proteins such as ferritin, rubredoxin, and thioredoxin; (iii) protein quality control systems such as HspA, HslO, and DnaK; and (iv) DNA repair proteins such as UspA and UvrB. These results suggest that strain SVR copes with antimony stress by modulating pleiotropic processes to resist and actively metabolize antimony. To the best of our knowledge, this is the first report to demonstrate the involvement of AnrA in Sb(V) respiration at the protein level. Furthermore, this is the first example to show high expression of the Ant system proteins in the Sb(V)-respiring bacterium.IMPORTANCEAntimony (Sb) exists mainly as antimonite [Sb(III)] or antimonate [Sb(V)] in the environment, and Sb(III) is more toxic than Sb(V). Recently, microbial involvement in Sb redox reactions has received attention. Although more than 90 Sb(III)-oxidizing bacteria have been reported, information on Sb(V)-reducing bacteria is limited. Especially, the enzyme involved in dissimilatory Sb(V) reduction, or Sb(V) respiration, is unclear, despite this pathway being very important for the circulation of Sb in nature. In this study, we demonstrated that the Sb(V) reductase (Anr) of an Sb(V)-respiring bacterium (Geobacter sp. SVR) is a novel member of the dimethyl sulfoxide (DMSO) reductase family. In addition, we found that strain SVR copes with Sb stress by modulating pleiotropic processes, including the Ant and Ars systems, and upregulating the antioxidant and quality control protein levels. Considering the abundance and diversity of putative anr genes in the environment, Anr may play a significant role in global Sb cycling in both marine and terrestrial environments.

Depositional environments and plant communities in the exceptional context of the Kungurian megacaldera of the Athesian Volcanic Group (Southern Alps, N-Italy)

We used a combined approach (lithofacies and palynology) and multivariate analyses to reconstruct the different depositional environments and changes in the plant communities throughout the middle to late Kungurian in the tropical Pangea. The late Paleozoic terrestrial biotas underwent changes under the pressure of a general aridification trend and a warming event that changed biota composition favoring drought-tolerant taxa during the Artinskian. Few studies integrate the different terrestrial ecosystem components to reconstruct palaeoenvironments and climate changes throughout the Cisuralian (early Permian). We analyzed several sedimentary successions of different stratigraphic positions intercalated in well-dated volcanic units of the megacaldera of the Athesian Volcanic Group (Southern Alps, northern Italy). The obtained palynofacies and quantitative sporomorph records with an exceptional high resolution (∼10 Ma) evidence a palaeoenvironmental/climatic change in the plant communities from the middle to the late Kungurian. The late Kungurian shows a higher diversity in the plant communities with a dominance of seed ferns and a higher relative abundance of xeromorphic-hygromorphic sporomorph taxa. This suggests the presences of more stable and putatively more humid environmental conditions in respect to the middle Kungurian. Furthermore, a direct comparison between lithofacies and all primary components of the palynofacies assemblages permits to characterize lacustrine and alluvial depositional environments since these studies are underrepresented for terrestrial environments.

A global compilation of diatom silica oxygen isotope records from lake sediment – trends and implications for climate reconstruction

Abstract. Oxygen isotopes in biogenic silica (δ18OBSi) from lake sediments allow for quantitative reconstruction of past hydroclimate and proxy-model comparison in terrestrial environments. The signals of individual records have been attributed to different factors, such as air temperature (Tair), atmospheric circulation patterns, hydrological changes, and lake evaporation. While every lake has its own local set of drivers of δ18O variability, here we explore the extent to which regional or even global signals emerge from a series of paleoenvironmental records. This study provides a comprehensive compilation and combined statistical evaluation of the existing lake sediment δ18OBSi records, largely missing in other summary publications (i.e. PAGES network). For this purpose, we have identified and compiled 71 down-core records published to date and complemented these datasets with additional lake basin parameters (e.g. lake water residence time and catchment size) to best characterize the signal properties. Records feature widely different temporal coverage and resolution, ranging from decadal-scale records covering the past 150 years to records with multi-millennial-scale resolution spanning glacial–interglacial cycles. The best coverage in number of records (N = 37) and data points (N = 2112) is available for Northern Hemispheric (NH) extratropical regions throughout the Holocene (roughly corresponding to Marine Isotope Stage 1; MIS 1). To address the different variabilities and temporal offsets, records were brought to a common temporal resolution by binning and subsequently filtered for hydrologically open lakes with lake water residence times &lt; 100 years. For mid- to high-latitude (&gt; 45° N) lakes, we find common δ18OBSi patterns among the lake records during both the Holocene and Common Era (CE). These include maxima and minima corresponding to known climate episodes, such as the Holocene Thermal Maximum (HTM), Neoglacial Cooling, Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). These patterns are in line with long-term air temperature changes supported by previously published climate reconstructions from other archives, as well as Holocene summer insolation changes. In conclusion, oxygen isotope records from NH extratropical lake sediments feature a common climate signal at centennial (for CE) and millennial (for Holocene) timescales despite stemming from different lakes in different geographic locations and hence constitute a valuable proxy for past climate reconstructions.

Iron Oxide (Magnetite)-Based Nanobiomaterial with Medical Applications-Environmental Hazard Assessment Using Terrestrial Model Species.

Nanobiomaterials (NBMs) have tremendous potential applications including in cancer diagnosis and treatment. However, the health and environmental effects of NBMs must be thoroughly assessed to ensure safety. Fe3O4 (magnetite) nanoparticles coated with polyethylene glycol (PEG) and poly (lactic-co-glycolic acid) (PLGA) were one of the focus NBMs within the EU project BIORIMA. Fe3O4 PEG-PLGA has been proposed to be used as a contrast agent in magnetic resonance imaging for the identification of solid tumors and has revealed low cytotoxicity in several cell lines. However, the effects of Fe3O4 PEG-PLGA have not been assessed in terrestrial environments, the eventual final sink of most materials. In the present study, the effects of Fe3O4 PEG-PLGA and its precursor, (un-coated) Fe3O4 NMs, were assessed in soil model invertebrates Enchytraeus crypticus (Oligochaeta) and Folsomia candida (Collembola). The endpoints were survival, reproduction, and size, based on the standard OECD test (28 days) and its extension (56 days). The results showed no toxicity for any of the endpoints evaluated, indicating that the NBM Fe3O4 PEG-PLGA poses no unacceptable risk to the terrestrial environment.

NEOICHNOLOGY OF TROPICAL AND ARID SCORPIONS: ENVIRONMENTAL IMPACTS ON BURROW CONSTRUCTION AND FORM

ABSTRACT Scorpions are intermediate predators in numerous terrestrial environments, and many are temporarily to permanently fossorial. As a result, they play key roles in terrestrial food webs, in soil development, and as ecosystem engineers. However, scorpions have a poorly described ichnofossil record likely due to an inadequate understanding of their trace morphology. Critical to correcting this is assessing the variability of burrows constructed by phylogenetically, geographically, and environmentally distinct scorpions. Five extant scorpions, Heterometrus spinifer, Pandinus imperator, Pandipalpus viatoris, Hadrurus arizonensis, and Paravaejovis spinigerus were studied through neoichnological experiments under varying substrate conditions. Burrow casts produced were described and compared across species and different substrate conditions. Tropical scorpions excavated sediment and carried it away from the burrow to produce open, straight-to-sinuous, subvertical tunnels to branching tunnel systems with single to multiple entrances and often chambers. Arid scorpions excavated with rapid leg movements to throw sediment behind the body to produce single to linked networks of U-shaped burrows as well as subvertical tunnels to tunnel networks with single to multiple entrances and rarely chambers. Changes in sediment composition and moisture tended to reduce burrow production but did not significantly alter burrow morphology. All scorpion burrows, regardless of species, bore a moderate-to-high similarity despite differences in excavation styles and architecture suggesting that scorpions produce burrows of consistent form regardless of phylogenetic or environmental distance. The result of these studies provides key ichnotaxobases of scorpion burrows which can be used to identify them in the fossil record and improve interpretations of ancient terrestrial ecosystems.

Prokaryotic richness and diversity increased during Holocene glacier retreat and onset of an Antarctic Lake

Knowledge about biodiversity changes during transitions from glacial landscape to lake formation is limited to contemporary studies. Here, we combined analyses of lithology, chronology and geochemistry with sedimentary ancient DNA metabarcoding to assess such transition in maritime Antarctica. We inferred three paleoenvironmental stages covering the Holocene glacier retreat process. From 4900 to 3850 years before the present, we found the lowest prokaryotic richness/diversity, with bacterial taxa indicators associated to soil and terrestrial environments. From 3850 to 2650 years before the present, a higher carbon content, higher Carbon/Nitrogen variability, increased species richness/diversity, and prokaryotic taxa indicators of long-term energy starvation were detected. Finally, from 2650 to 1070 years before the present, we inferred the onset of a genuine lacustrine environment holding stable Carbon/Nitrogen ratios and the highest prokaryotic diversity, with known aquatic bacterial taxa. Our study unveils for the first time the evolution from a glacier-covered to a freshwater lake through a millennial scale.