Effects of temperature and copper pollution on soil community--extreme temperature events can lead to community extinction

Effect of Biodegradable Nonwoven Mulches from Natural and Renewable Sources on Lettuce Cultivation

Numerous research showed that mulching with conventional agro foils elevates soil temperature and promotes plant growth, but negatively influences soil health and brings environmental concerns. Most of the published research on nonwoven mulches for plant cultivation includes nonwoven fabrics produced by extrusion processes providing nonwoven fabric structures similar to films. A limited number of studies investigate the impact of nonwoven mulches produced by a mechanical process on the cards and bonded by needling on plant cultivation. For this study, nonwoven mulches of mass per unit area of 400 g m-2 made from jute, hemp, viscose (CV), and polylactide (PLA) fibers were produced on the card bonded by needle punching. The field experiment was conducted two consecutive years in a row, in spring 2022 and 2023, by planting lettuce seedlings. The nonwoven mulches maintain lower temperatures and higher soil moisture levels compared to agro foil and the control field. The fibrous structure and their water absorption properties allow natural ventilation, regulating temperatures and retaining moisture of soil, consequently improving soil quality, lettuce yield, and quality. The fiber type from which the mulches were produced, influenced soil temperature and humidity, soil quality, and lettuce cultivation. The nonwoven mulches were successful in weed control concerning the weediness of the control field. Based on the obtained results, the newly produced mulches are likely to yield better results when used for the cultivation of vegetables with longer growing periods. Newly produced biodegradable nonwoven mulches could be an eco-friendly alternative to traditional agro foil, minimizing environmental harm during decomposition. The obtained results suggest that the newly produced mulches would be even more suitable for growing vegetables with longer growing seasons.

Simultaneous Dissemination of Nanoplastics and Antibiotic Resistance by Nematode Couriers

Nanoplastics (NPs) are increasingly recognized as a newly emerging pollutant in the environment. NPs can enable the colonization of microbial pathogens on their surfaces and adsorb toxic pollutants, such as heavy metals and residual antibiotics. Although the dissemination of plastic particles in water bodies and the atmosphere is widely studied, the dissemination of NPs and adsorbed pollutants on land, via biological means, is poorly understood. Since soil animals, such as the bacterivorous nematode Caenorhabditis elegans (C. elegans), are highly mobile, this raises the possibility that they play an active role in disseminating NPs and adsorbed pollutants. Here, we established that antibiotic-resistant bacteria could aggregate with antibiotic-adsorbed NPs to form antibiotic-adsorbed NP-antibiotic resistant bacteria (ANP-ARB) aggregates, using polymyxins (colistin) as a proof-of-concept. Colistin-resistant mcr-1 bearing Escherichia coli from a mixed population of resistant and sensitive bacteria selectively aggregate with colistin-ANPs. In the soil microcosm, C. elegans fed on ANP-ARB clusters, resulting in the rapid spread of ANP-ARB by the nematodes across the soil at a rate of 40-60 cm per day. Our work revealed insights into how NPs could still disseminate across the soil faster than previously thought by "hitching a ride" in soil animals and acting as agents of antibiotic-resistant pathogens and antibiotic contaminants. This poses direct risks to ecology, agricultural sustainability, and human health.

The effects of pollution by multiple metals derived from long-term smelting activities on soil mite communities in arable soils under different land use types in East China

Soil pollution represents a threat to soil biodiversity and to soil and human health. However, many ecotoxicological issues, such as the impact of heavy metal pollution on the soil mite community and its spatial distribution in areas with complex environmental factors, are not fully understood. Here, an investigation was conducted in an arable area (about 11 km²) enclosed by surrounding mountains. The study area was contaminated with potentially toxic metals derived from copper smelting that was functioning for over 10 years. The area comprised four land use types: woodlands, dry fields, paddy fields, and wastelands, and was divided into 141 study sites each with an area of 6.25 ha. The soil metal (Cu, Zn, Pb, and Cd) contents, pH, and organic matter were determined and their distributions were established. Furthermore, soil mite (Acari) community properties (species richness, individual abundance, and Shannon-Wiener diversity index) were determined, and the distributions of total species number and abundance were ascertained. Soil metal pollution strongly reduced soil mite community, but the effects depended on mite groups or species and their sensitivity to different metals as well as land use types. CANOCO analysis revealed that the order Oribatida was more highly correlated with soil metal contents, whereas the other three orders responded to soil metal contents depending on land use types, mite properties, or metals. SADIE method indicated that the coordinate relationship between mite species number and metal concentration was more negative (4-25% of the study sites) than positive (4-12%). The metal pollution levels in the soil were evaluated by single and integrated pollution and ecological risk indices.

Community reassemblies of eukaryotes, prokaryotes, and viruses in the hexabromocyclododecanes-contaminated microcosms

The microbial community in seriously contaminated environment were not well known. This research investigated the community reassemblies in microcosms made of two distinct mangrove sediments amended with high levels of hexabromocyclododecanes (HBCDs). After eight months of contamination, the transformation of HBCDs yielded various lower brominated products and resulted in acidification (pH ~2). Therefore, the degraders and dehalogenase homologous genes involved in transformation of HBCDs only presented in low abundance to avoid further deterioration of the habitats. Moreover, in these deteriorated habitats, 1344 bacterial, 969 archaeal, 599 eukaryotic (excluded fungi), 187 fungal OTUs, and 10 viral genera, were reduced compared with controls. Specifically, in two groups of microcosms, Zetaproteobacteria, Deinococcus-Thermus, Spirochaetes, Bacteroidetes, Euryarchaeota, and Ascomycota, were positively responding taxa to HBCDs. Caloneis (Bacillariophyta) and Ascomycota turned to the dominant eukaryotic and fungal taxa. Most of predominant taxa were related to the contamination of brominated flame retardants (BFRs). Microbial communities were reassembled in divergent and sediment-dependent manner. The long-term contamination of HBCDs leaded to the change of relations between many taxa, included some of the environmental viruses and their known hosts. This research highlight the importance of monitoring the ecological effects around plants producing or processing halogenated compounds.

Searching for Silphium: An Updated Review

From luxury spice to medical cure-all, silphium was a product coveted throughout the ancient world and occupied an essential place in the export economy of ancient Cyrene. The mysterious extinction of the silphium plant in the 1st century CE leaves us with little evidence as to the exact nature of this important agricultural product. In this paper, an historical background on the kingdom of Cyrene is provided, evidence for the nature of the silphium plant is reviewed, how and why it was consumed and traded is discussed. Possible causes of extinction are considered in the context of plant genetics, biometrics, and soil geochemistry. Next, we demonstrate how modern medical studies conducted on possible living relatives can inform us about claims made by ancient authors as to the medical uses of the silphium plant, including its use as a contraceptive and abortifacient. Finally, methods for recovering silphium are explored. We show how underwater archaeology and the search for ancient shipwrecks off the northern coast of Libya may offer our best chance for the recovery of botanical remains of ancient silphium, and how ancient DNA may be able to establish the genetic makeup of this elusive plant.

Current ionising radiation doses in the Chernobyl Exclusion Zone do not directly impact on soil biological activity

Although soil organisms are essential for ecosystem function, the impacts of radiation on soil biological activity at highly contaminated sites has been relatively poorly studied. In April-May 2016, we conducted the first largescale deployment of bait lamina to estimate soil organism (largely soil invertebrate) feeding activity in situ at study plots in the Chernobyl Exclusion Zone (CEZ). Across our 53 study plots, estimated weighted absorbed dose rates to soil organisms ranged from 0.7 μGy h^-1 to 1753 μGy h^-1. There was no significant relationship between soil organism feeding activity and estimated weighted absorbed dose rate. Soil biological activity did show significant relationships with soil moisture content, bulk density (used as a proxy for soil organic matter) and pH. At plots in the Red Forest (an area of coniferous plantation where trees died because of high radiation exposure in 1986) soil biological activity was low compared to plots elsewhere in the CEZ. It is possible that the lower biological activity observed in the Red Forest is a residual consequence of what was in effect an acute high exposure to radiation in 1986.

Annelid genomes: Enchytraeus crypticus, a soil model for the innate (and primed) immune system

Enchytraeids (Annelida) are soil invertebrates with worldwide distribution that have served as ecotoxicology models for over 20 years. We present the first high-quality reference genome of Enchytraeus crypticus, assembled from a combination of Pacific Bioscience single-molecule real-time and Illumina sequencing platforms as a 525.2 Mbp genome (910 gapless scaffolds and 18,452 genes). We highlight isopenicillin, acquired by horizontal gene transfer and conferring antibiotic function. Significant gene family expansions associated with regeneration (long interspersed nuclear elements), the innate immune system (tripartite motif-containing protein) and response to stress (cytochrome P450) were identified. The ACE (Angiotensin-converting enzyme) - a homolog of ACE2, which is involved in the coronavirus SARS-CoV-2 cell entry - is also present in E. crypticus. There is an obvious potential of using E. crypticus as a model to study interactions between regeneration, the innate immune system and aging-dependent decline.

Synergistic interaction between effects of phenanthrene and dynamic heat stress cycles in a soil arthropod

Climatic stressors and chemicals should not be treated as isolated problems since they often occur simultaneously, and their combined effects must be evaluated including their possible interactive effects. In the present study we subjected springtails (Folsomia candida) to combined exposure to phenanthrene and dynamic heat cycles in a full factorial experiment. In a microcosm experiment, we studied the population growth of springtails subjected to a range of sub-lethal concentrations of phenanthrene. During the 28-day experiment we further subjected microcosms to varying numbers of repeated dynamic heat cycles (0-5 cycles) simulating repeated heat waves. We found a synergistic interaction between the effects of phenanthrene and the number of heat waves on both body mass of adults and juvenile production of F. candida showing that the negative effects of phenanthrene were intensified when animals were heat stressed, and/or vice versa. This interaction was not related to internal concentrations of phenanthrene in adult springtails, nor was it due to altered degradation of phenanthrene in soil. We argue that both phenanthrene (by its partitioning into membrane bilayers) and heat have detrimental effects on the physical conditions of cellular membranes in a dose-dependent manner, which, under extreme circumstances, can increase membrane fluidity to a level which is sub-optimal for normal membrane functioning. We discuss the possibility that the synergistic interactions subsequently reduce life-history parameters such as growth and reproduction.

Assessing the toxicity of safer by design CuO surface-modifications using terrestrial multispecies assays

Safer by design (SBD) modifications of nanomaterials (NMs) have been pursued, aiming to maintain functionality and yet reduce hazard and support sustainable nanotechnology. The present case study involves copper oxide nanomaterials (CuO NMs) used in paint that have been surface modified by a SBD approach to particles coated with citrate (CIT^-), ascorbate (ASC^-), polyethylenimine (PEI⁺), and polyvinylpyrrolidone (PVP). We assessed the effect of the 4 different surface modified (CIT, ASC, PVP and PEI) NMs plus the pristine non-coated (PRI NM) and a Cu salt (CuCl₂), using the soil multispecies test system (samples at 28-56-84 days). Further, the species were tested individually, and Cu was measured in the test media (soil and soil solution) and organisms. There was a potential relationship with zeta potential, and toxicity of CuO NMs was as follows: -PEI (+28 mV) caused the least impact, -ASC and -CIT (-17 mV, -18 mV) the most, while PVP and PRI (-8 mV, -9 mV) caused an intermediate response. Differences were not explained by the contribution of soluble Cu. Coating interfered with the release of Cu²⁺ and/or the activation of copper regulators and detoxification mechanisms in the organisms, i.e. time to reach some kind of stability in organisms' uptake was shorter for -ASC and longer for -PVP during prolonged time. Thus, one of the main findings is that NMs hazard assessment requires long term testing to understand predicted effects across materials. Further, the coverage using a multispecies approach offers increased relevance and a more ecosystem qualified response.

Inadequacy of typical physiological experimental protocols for investigating consequences of stochastic weather events emerging from global warming

Increasingly variable, extreme, and nonpredictable weather events are predicted to accompany climate change, and such weather events will especially affect temperate, terrestrial environments. Yet, typical protocols in comparative physiology that examine environmental change typically employ simple step-wise changes in the experimental stressor of interest (e.g., temperature, water availability, oxygen, nutrition). Such protocols fall short of mimicking actual natural environments and may be inadequate for fully exploring the physiological effects of stochastic, extreme weather events. Indeed, numerous studies from the field of thermal biology, especially, indicate nonlinear and sometimes counterintuitive findings associated with variable and fluctuating (but rarely truly stochastic) protocols for temperature change. This Perspective article suggests that alternative experimental protocols should be employed that go beyond step-wise protocols and even beyond variable protocols employing circadian rhythms, for example, to those that actually embrace nonpredictable elements. Such protocols, though admittedly more difficult to implement, are more likely to reveal the capabilities (and, importantly, the limitations) of animals experiencing weather, as distinct from climate. While some possible protocols involving stochasticity are described as examples to stimulate additional thought on experimental design, the overall goal of this Perspective article is to encourage comparative physiologists to entertain incorporation of nonpredictable experimental conditions as they design future experimental protocols.

Combined effect of temperature and copper pollution on soil bacterial community: climate change and regional variation aspects

The aim of this study was to assess the combined effects of temperature and copper (Cu) contamination in the structure of soil bacterial community. For this, contaminated or spiked and control soils from two different geographic origins (PT-Portugal and DK-Denmark) were used. The DK soil was from a historically contaminated study field, representing a long-term exposure to Cu while the PT soil was from a clean site and freshly spiked with Cu. Soil bacterial communities were exposed in mesocosms during 84 days to 3 different temperatures based on values typically found in each geographic region and temperature conditions that simulated a warming scenario. Obtained results indicate that Cu stress alters the structure of bacterial community and that this effect is, to some extent, temperature-dependent. Effects on bacterial diversity for both soils were also observed. Differences in the DK and PT communities' response were apparent, with the community from the historically contaminated soil being more resilient to temperature fluctuations. This study presents evidence to support the hypothesis that temperature alters the effect of metals on soils. Further, our results suggest that the definition of soils quality criteria must be based on studies performed under temperatures selected for the specific geographic region. Studies taking into account temperature changes are needed to model and predict risks, this is important to e.g. future adjustments of the maximum permissible levels for soil metal contamination.

A conceptual framework for the emerging discipline of conservation physiology

Current rates of biodiversity decline are unprecedented and largely attributed to anthropogenic influences. Given the scope and magnitude of conservation issues, policy and management interventions must maximize efficiency and efficacy. The relatively new field of conservation physiology reveals the physiological mechanisms associated with population declines, animal-environment relationships and population or species tolerance thresholds, particularly where these relate to anthropogenic factors that necessitate conservation action. We propose a framework that demonstrates an integrative approach between physiology, conservation and policy, where each can inform the design, conduct and implementation of the other. Each junction of the conservation physiology process has the capacity to foster dialogue that contributes to effective implementation, monitoring, assessment and evaluation. This approach enables effective evaluation and implementation of evidence-based conservation policy and management decisions through a process of ongoing refinement, but may require that scientists (from the disciplines of both physiology and conservation) and policy-makers bridge interdisciplinary knowledge gaps. Here, we outline a conceptual framework that can guide and lead developments in conservation physiology, as well as promote innovative research that fosters conservation-motivated policy.