Effects of seasonal precipitation regimes on microbial biomass and extracellular enzyme activity during shrub foliar litter decomposition in a subtropical forest

Elucidating the mechanisms underlying microbial biomass and extracellular enzyme activity responses to the seasonal precipitation regime during foliar litter decomposition is highly important for understanding the material cycle of forest ecosystems in the context of global climate change; however, the specific underlying mechanisms remain unclear. Hence, a precipitation manipulation experiment involving a control (CK) and treatments with decreased precipitation in the dry season and extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season and proportionally increased precipitation in the wet season (IP) was conducted in a subtropical evergreen broad-leaved forest in China from October 2020 to October 2021. The moisture, microbial biomass, and extracellular enzyme activities of foliar litter from two dominant shrub species, Phyllostachys violascens and Alangium chinense, were measured at six stages during the dry and wet seasons. The results showed that (1) both IE and IP significantly decreased the microbial biomass carbon and microbial biomass nitrogen content and the activities of β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, acid phosphatase and cellulase in the dry season, while the opposite effects were observed in the wet season. (2) Compared with those of IE, the effects of IP on foliar litter microbial biomass and extracellular enzyme activity were more significant. (3) The results from the partial least squares model indicated that extracellular enzyme activity during foliar litter decomposition was strongly controlled by the foliar litter water content, microbial biomass nitrogen, the ratio of total carbon to total phosphorus, foliar litter total carbon, and foliar litter total nitrogen. These results provide an important theoretical basis for elucidating the microbial mechanisms driving litter decomposition in a subtropical forest under global climate change scenarios.

The relational shift in urban ecology: From place and structures to multiple modes of coproduction for positive urban futures

This perspective emerged from ongoing dialogue among ecologists initiated by a virtual workshop in 2021. A transdisciplinary group of researchers and practitioners conclude that urban ecology as a science can better contribute to positive futures by focusing on relationships, rather than prioritizing urban structures. Insights from other relational disciplines, such as political ecology, governance, urban design, and conservation also contribute. Relationality is especially powerful given the need to rapidly adapt to the changing social and biophysical drivers of global urban systems. These unprecedented dynamics are better understood through a relational lens than traditional structural questions. We use three kinds of coproduction-of the social-ecological world, of science, and of actionable knowledge-to identify key processes of coproduction within urban places. Connectivity is crucial to relational urban ecology. Eight themes emerge from the joint explorations of the paper and point toward social action for improving life and environment in urban futures.

The exposure of the world's mountains to global change drivers

Global change affects mountain areas at different levels, with some mountains being more exposed to change in climate or environmental conditions and others acting as local refugia. We quantified the exposure of the world's mountains to three drivers of change, climate, land use, and human population density, using two spatial-temporal metrics (velocity and magnitude of change). We estimated the acceleration of change for these drivers by comparing past (1975-2005) vs. future (2020-2050) exposure, and we also compared exposure in lowlands vs. mountains. We found Africa's tropical mountains facing the highest future exposure to multiple drivers of change, thus requiring targeted adaptation and mitigation strategies to preserve biodiversity. European and North America's mountains, in contrast, experience more limited exposure to global change and could act as local refugia for biodiversity. This knowledge can be used to prioritize local-scale interventions and planning long-term monitoring to reduce the risks faced by mountain biodiversity.

Nighttime warming and nitrogen addition effects on the microclimate of a freshwater wetland dominated by Phragmites australis

The critical impacts of microclimate on carbon (C) cycling have been widely reported. However, the potential effects of global change on wetland microclimate remain unclear, primarily because of the absence of field manipulative experiment in inundated wetland. This study was designed to examine the effects of nighttime warming and nitrogen (N) addition on air, water, and sediment temperature and also reveal the controlling factors in a Phragmites australis dominated freshwater wetland on the North China Plain. Nighttime warming increased daily air, water, and sediment temperature by 0.24 °C, 0.27 °C, and 0.36 °C, respectively. The diurnal temperature range of water was decreased by 0.44 °C under nighttime warming, whereas warming had no effect on diurnal temperature range of air and sediment. In addition, N addition caused a reduction of 0.20 °C and 0.14 °C in daily water and sediment temperature by increasing vegetation coverage. There was a significant interaction between nighttime warming and N addition on water temperature. Furthermore, the vapor pressure deficit is the main factor affecting the extent of the warming-induced increases in air temperature. The changes of height and leaf area index of Phragmites australis are responsible for the cooling effects in the N addition plots. This study provides empirical evidence for the positive climate warming - microclimate feedback in freshwater wetland. However, N deposition leads to decreased water and sediment temperature. Our findings highlight the importance of incorporating the differential impacts of nighttime warming and N addition on air, water, and sediment temperature into the predictions of wetland C cycling responses to climate change.

Naïve and induced tolerance of 15 amphibian populations to three commonly applied insecticides

Human impacts on ecological communities are pervasive and species must either move or adapt to changing environmental conditions. For environments polluted by contaminants, researchers have found hundreds of target pest species evolving increased tolerance, but we have substantially fewer cases of evolved tolerance in non-target species. When species do evolve increased tolerance, inducible tolerance can provide immediate protection and favor the evolution of increased tolerance over generations via genetic assimilation. Using a model larval amphibian (wood frogs, Rana sylvatica), we examined the tolerance of 15 populations from western Pennsylvania and eastern New York (USA), when first exposed to no pesticide or sublethal concentrations and subsequently exposed to lethal concentrations of three common insecticides (carbaryl, chlorpyrifos, and diazinon). We found high variation in naïve tolerance among the populations for all three insecticides. We also discovered that nearly half of the populations exhibited inducible tolerance, though the degree of inducible tolerance (magnitude of tolerance plasticity; MoTP) varied. We observed a cross-tolerance pattern of the populations between chlorpyrifos and diazinon, but no pattern of similar MoTP among the pesticides. With populations combined from two regions, increased tolerance was not associated with proximity to agricultural fields, but there were correlations between proximity to agriculture and MoTP. Collectively, these results suggests that amphibian populations possess a wide range of naïve tolerance to common pesticides, with many also being able to rapidly induce increased tolerance. Future research should examine inducible tolerance in a wide variety of other taxa and contaminants to determine the ubiquity of these responses to anthropogenic factors.

Later-melting rather than thickening of snowpack enhance the productivity and alter the community composition of temperate grassland

Snowpack is closely related to vegetation green-up in water-limited ecosystems, and has effects on growing-season ecosystem processes. However, we know little about how changes in snowpack depth and melting timing affect primary productivity and plant community structure during the growing season. Here, we conducted a four-year snow manipulation experiment exploring how snow addition, snowmelt delay and their combination affect aboveground net primary productivity (ANPP), species diversity, community composition and plant reproductive phenology in seasonally snow-covered temperate grassland in northern China. Snow addition alone increased soil moisture and nutrient availability during early spring, while did not change plant community structure and ANPP. Instead, snowmelt delay alone postponed plant reproductive phenology, and increased ANPP, decreased species diversity and altered species composition. Grasses are more sensitive to changes in snowmelt timing than forbs, and early-flowering forbs showed a higher sensitivity compared to late-flowering forbs. The effect of snowmelt delay on ANPP and species diversity was offset by snow addition, probably because the added snow unnecessarily lengthens the snow-covering duration. The disparate effects of changes in snowpack depth and snowmelt timing necessitate their discrimination for more mechanistic understanding on the effects of snowpack changes on ecosystems. Our study suggests that it is essential to incorporate non-growing-season climate change events (in particular, snowfall and snowpack changes) to comprehensively disclose the effects of climate change on community structure and ecosystem functions.

Anthropogenic noise limits resource distribution without changing social hierarchies

Increasing evidence demonstrates that anthropogenic noise is a global pollutant that threatens marine ecosystems. Mounting numbers of studies show its diverse effects on individuals and their behaviour. However, little is known about how individual changes in response to anthropogenic noise could cascade through groups and populations affecting resource distribution vital for survival and fitness. Here we test the hypotheses that anthropogenic noise could alter resource distribution, associated hierarchies and consequently individual benefits. We used groups of hermit crabs, a globally distributed model system for assessing impacts of environmental change on wildlife and measured in controlled laboratory conditions the resource distribution of their reusable shelters (gastropod shells) under ship noise and ambient control playbacks. We applied vacancy chain theory to test three predictions about how new resource units create benefits for a population. A new resource unit leads to (i) a cascade of resource abandonments and acquisitions (= chain of vacancy moves) based on an internal (ii) hierarchy (here size-based) which allows (iii) more than one individual to benefit. All three predictions were supported under control sound. Under anthropogenic noise however, fewer individuals benefitted from the arrival of a new, empty shell, while the size-based hierarchy was maintained. The latter was apparent in chain structures, which were concordant between sound treatments. This experiment shows that anthropogenic noise can affect individual behaviours that cascade through groups. This has the potential to disrupt wider resource distribution in populations.

Assessing coastal vulnerability at the village level using a robust framework, the example of Canacona in South Goa, India

Climate change poses a significant threat to coastal regions worldwide. This study presents and applies a modified Coastal Vulnerability Index (CVI) to assess coastal vulnerability at the village level, focusing on Canacona, a taluka in South Goa, India. It adapts the existing CVI methodology by incorporating additional variables to better represent the various dimensions of vulnerability, resulting in 21 variables split into a Physical Vulnerability Index (PVI) and a Social Vulnerability Index (SoVI). The results show spatial variability in coastal vulnerability across the studied villages, with Agonda and Nagercem-Chaudi found to be highly vulnerable and Loliem to be the least vulnerable. A hydrological modeling approach is also used to compare the CVI of every village with their susceptibility to inundation due to rising sea levels. The results demonstrate the influence of local factors on vulnerability, challenging previous taluka-level assessments given the scale upon which adaptation typically takes place.

Citizen science initiatives document biodiversity baselines at an urban lake

Changes to biodiversity from urbanization are occurring worldwide, and baseline data is vital to document the magnitude and direction of these alterations. We set out to document the biodiversity of an urban lake in Eastern Iowa that was devoid of baseline data prior to a renovation project that will convert the site into a major area for human recreation. Throughout the course of one year, we studied the biodiversity at Cedar Lake utilizing the citizen-science application iNaturalist coupled with semi-structured BioBlitz events, which we compared to previous opportunistic observations at the site. From a semi-structured approach to document biodiversity with citizen science, our analyses revealed more diverse community metrics over a shorter period compared to more than a decade of prior observations.

Using a metabolomics approach to investigate the sensitivity of a potential Arctic-invader and its Arctic sister-species to marine heatwaves and traditional harvesting disturbances

Coastal species are threatened by fishing practices and changing environmental conditions, such as marine heatwaves (MHW). The mechanisms that confer tolerance to such stressors in marine invertebrates are poorly understood. However, differences in tolerance among different species may be attributed to their geographical distribution. To test the tolerance of species occupying different thermal ranges, we used two closely related bivalves the softshell clam Mya arenaria (Linnaeus, 1758), a cold-temperate invader with demonstrated potential for establishment in the Arctic, and the blunt gaper Mya truncata (Linnaeus, 1758), a native polar species. Clams were subjected to a thermal stress, mimicking a MHW, and harvesting stress in a controlled environment. Seven acute temperature changes (2, 7, 12, 17, 22, 27, and 32 °C) were tested at two harvesting disturbance intensities (with, without). Survival was measured after 12 days and three tissues (gills, mantle, and posterior adductor muscle) collected from surviving individuals for targeted metabolomic profiling. MHW tolerance differed significantly between species: 26.9 °C for M. arenaria and 17.8 °C for M. truncata, with a negligeable effect of harvesting. At the upper thermal limit, M. arenaria displayed a more profound metabolomic remodelling when compared to M. truncata, and this varied greatly between tissue types. Network analysis revealed differences in pathway utilization at the upper MHW limit, with M. arenaria displaying a greater reliance on multiple DNA repair and expression and cell signalling pathways, while M. truncata was limited to fewer pathways. This suggests that M. truncata is ill equipped to cope with warming environments. MHW patterning in the Northwest Atlantic may be a strong predictor of population survival and future range shifts in these two clam species. As polar environments undergo faster rates of warming compared to the global average, M. truncata may be outcompeted by M. arenaria expanding into its native range.

Human activity has increasingly affected recent carbon accumulation in Zhanjiang mangrove wetland, South China

Mangrove wetlands are an important component of blue carbon (C) ecosystems, although the anthropogenic impact on organic C accumulation rate (OCAR) in mangrove wetlands is not yet clear. Three sediment cores were collected from Zhanjiang Gaoqiao Mangrove Reserve in Southern China, dated by 210Pb and 137Cs, and physico-chemical parameters measured. Results show that the OCARs in mangroves and grasslands have significantly increased by 4.4 and 1.3 times, respectively, since 1950, which is consistent with the transformation of organic C sources and the increase of sedimentation rate. This increment is due to increased soil erosion and nutrient enrichment caused by land use change and the discharge of fertilizer runoff and aquaculture wastewater. This study provides clear evidence for understanding the changes in organic C accumulation processes during the Anthropocene and is conducive to promoting the realization of C peak and neutrality targets.

Intensifying urban imprint on land surface warming: Insights from local to global scale

Increasing urbanization exacerbates surface energy balance perturbations and the health risks of climate warming; however, it has not been determined whether urban-induced warming and attributions vary from local, regional, to global scale. Here, the local surface urban heat island (SUHI) is evidenced to manifest with an annual daily mean intensity of 0.99°C-1.10°C during 2003-2018 using satellite observations over 536 cities worldwide. Spatiotemporal patterns and mechanisms of SUHI tightly link with climate-vegetation conditions, with regional warming effect reaching up to 0.015°C-0.138°C (annual average) due to surface energy alterations. Globally, the SUHI footprint of 1,860 cities approximates to 1% of the terrestrial lands, about 1.8-2.9 times far beyond the urban impervious areas, suggesting the enlargements of the imprint of urban warming from local to global scales. With continuous development of urbanization, the implications for SUHI-added warming and scaling effects are considerably important on accelerating global warming.

Thermal acclimation uncovers a simple genetic basis of adaptation to high temperature in a cosmopolitan pest

Understanding a population's fitness heterogeneity and genetic basis of thermal adaptation is essential for predicting the responses to global warming. We examined the thermotolerance and genetic adaptation of Plutella xylostella to exposure to hot temperatures. The population fitness parameters of the hot-acclimated DBM strains varied in the thermal environments. Using genome scanning and transcription profiling, we find a number of genes potentially involved in thermal adaptation of DBM. Editing two ABCG transporter genes, PxWhite and PxABCG, confirmed their role in altering cuticle permeability and influencing thermal responses. Our results demonstrate that SNP mutations in genes and changes in gene expression can allow DBM to rapidly adapt to thermal environment. ABCG transporter genes play an important role in thermal adaptation of DBM. This work improves our understanding of genetic adaptation mechanisms of insects to thermal stress and our capacity to predict the effects of rising global temperatures on ectotherms.

Twenty-five years of Open-Top Chambers in tropical environments: where, how, and what are we looking at regarding flora response to climate change?

MAIN CONCLUSION

Open-Top Chambers should be more used in tropical ecosystems to study climate change effects in plants as they are still insufficient to extract plant response patterns in these ecosystems. Understanding flora response to climate change (CC) is critical for predicting future ecosystem dynamics. Open-Top Chambers (OTCs) have been widely used to study the effects of CC on plants and are very popular in temperate ecosystems but are still underused in tropical regions. In this systematic review, we aimed to discuss the use of OTCs in the study of the effects of different agents of climate change on tropical flora by presenting scientometric data, discussing the technical aspects of its use and enumerating some observations on plant response patterns to climatic alterations in the tropics. Our analysis indicated that the bottleneck in choosing an OTC shape is not strictly related to its purpose or the type of parameter modulated; instead, passive or active approaches seem to be a more sensitive point. The common critical point in using this technique in warmer regions is overheating and decoupling, but it can be overcome with simple adaptations and extra features. The most frequently parameter modulated was CO2, followed by O3 and temperature. The plant families with more representatives in the studies analyzed were Fabaceae, Myrtaceae, and Poaceae, and the most represented biome was tropical and subtropical moist broadleaf forests. In conclusion, OTCs are a valuable and feasible tool to study CC effects on various tropical ecosystems, regardless of structure, active/passive approach, or other technical features. One of the primary advantages of this methodology is its applicability for in situ use, eliminating the need for plant transplantation. We encourage studies using OTC experimental design for plant conservation in the tropics.

Thermokarst lakes are hotspots of antibiotic resistance genes in permafrost regions on the Qinghai-Tibet Plateau

Antibiotic resistance genes (ARGs) are natural products and emerging pollutants in remote environments, including permafrost regions that are rapidly thawing due to climate warming. We investigated the role of thermokarst lakes (including sediment and water) in reserving ARGs compared to permafrost soils across the permafrost regions on the Qinghai-Tibet Plateau. As intrinsically connected distinct environments, permafrost soil, lake sediment, and lake water harbored 1239 ARGs in total, while a considerable number of same ARGs (683 out of 1239) concurrently presented in all these environments. Soil and sediment had a higher number of ARGs than water. Multidrug resistance genes were the most diverse and abundant in all three environments, where cls, ropB, mdfA, fabI, and macB were the top five most abundant ARGs while with different orders. Soil and sediment had similar ARG profiles, and the alpha and beta diversity of ARGs in sediment were positively correlated with that in soil. The beta diversity of ARG profiles between sediment and soil was highly contributed by turnover component (89%). However, turnover and nestedness components were almost equality contributed (46%-54%) to the beta diversity of ARG profiles between soil and water as well as between sediment and water. The results suggested that thermokarst lake sediments might inherit the ARGs in permafrost soils. Water ARGs are the subset of soil ARGs and sediment ARGs to a certain degree with species turnover playing a significant role. When accounting the ARGs in sediment and water together, thermokarst lakes had a significantly higher number of ARGs than permafrost soils, suggesting that thermokarst lakes act as the hotspots of ARGs in permafrost regions. These findings are disturbing especially due to the fact that tremendous number of thermokarst lakes are forming under accelerating climate change.

Microplastic leachates inhibit small-scale self-organization in mussel beds

Self-organized spatial patterns are increasingly recognized for their contribution to ecosystem functioning. They can improve the ecosystem's ability to respond to perturbation and thus increase its resilience to environmental stress. Plastic pollution has now emerged as major threat to aquatic and terrestrial biota. Under laboratory conditions, we tested whether plastic leachates from pellets collected in the intertidal can impair small-scale, spatial self-organization and byssal threads production of intertidal mussels and whether the effect varied depending on where the pellets come from. Specifically, leachates originating from plastic pellets collected from relatively pristine and polluted areas respectively impaired and inhibited the ability of mussels to self-organize at small-scale and to produce byssal threads compared to control conditions (i.e., seawater without leaching solution). Limitations to natural self-organizing processes and threads formation may translate to a declined capacity of natural ecosystems to avoid tipping points and to a reduced restoration success of disturbed ecosystems.

How do small dams alter river food webs? A food quality perspective along the aquatic food web continuum

Damming of rivers poses a significant threat to freshwater ecosystems. Previous studies about the impact of damming on river ecosystems have mostly focused on large dams, with the impact of small dams largely unknown. Further, while the impacts of dams on aquatic communities have been widely studied, the effect on energy flow across river food webs remains unclear. In recent years, long-chain polyunsaturated fatty acid analysis (LC-PUFA) has emerged as a promising technique for assessing food quality and trophic interactions. In this study, LC-PUFA was applied to explore the nutritional effects of small dams on river food webs. A field investigation was conducted at upstream and downstream areas of three small dams in the headwaters of Dongjiang River, China, to evaluate the impact of small dams on the nutritional quality of basal food sources, and their consequent impacts on aquatic consumers and trophic links. Basal food sources (i.e., submerged leaves, macrophytes and periphyton) and aquatic consumers (i.e., macroinvertebrates and fish) were collected, and their fatty acid (FA) composition was measured. Our results showed that periphyton, rather than submerged leaves and macrophytes, was the primary high-quality food source for aquatic consumers, providing them with LC-PUFA, irrespective of whether sites were upstream or downstream. Damming the streams induced changes in aqueous nutrient concentrations (TP, PO4-P, DIN, and TN) from upstream to downstream of the dams, leading to significant variation in periphyton FA content. Compared with periphyton collected at downstream sites, periphyton at upstream sites contained higher LC-PUFA, but lower short-chain PUFA. Differences in periphyton LC-PUFA between the upstream and downstream areas of dams were reflected in the FA profiles of invertebrate grazers and filterers, and further transferred to fish. Furthermore, decreased periphyton nutritional quality at the downstream of the dams was one of the reasons for the simplification of stream food webs. Our results indicated that small dams negatively affected food webs, emphasizing the importance of high-quality food sources for stream ecosystems. We suggest that the trophic integrity of river food webs hinges on the dietary availability of periphyton supplying physiologically highly required nutrients for consumers and must thus not be compromised by damming of streams or other alterations.

Double jeopardy: global change and interspecies competition threaten Siberian cranes

Anthropogenic global change is precipitating a worldwide biodiversity crisis, with myriad species teetering on the brink of extinction. The Arctic, a fragile ecosystem already on the frontline of global change, bears witness to rapid ecological transformations catalyzed by escalating temperatures. In this context, we explore the ramifications of global change and interspecies competition on two arctic crane species: the critically endangered Siberian crane (Leucogeranus leucogeranus) and the non-threatened sandhill crane (Grus canadensis). How might global climate and landcover changes affect the range dynamics of Siberian cranes and sandhill cranes in the Arctic, potentially leading to increased competition and posing a greater threat to the critically endangered Siberian cranes? To answer these questions, we integrated ensemble species distribution models (SDMs) to predict breeding distributions, considering both abiotic and biotic factors. Our results reveal a profound divergence in how global change impacts these crane species. Siberian cranes are poised to lose a significant portion of their habitats, while sandhill cranes are projected to experience substantial range expansion. Furthermore, we identify a growing overlap in breeding areas, intensifying interspecies competition, which may imperil the Siberian crane. Notably, we found the Anzhu Islands may become a Siberian crane refuge under global change, but competition with Sandhill Cranes underscores the need for enhanced conservation management. Our study underscores the urgency of considering species responses to global changes and interspecies dynamics in risk assessments and conservation management. As anthropogenic pressures continue to mount, such considerations are crucial for the preservation of endangered species in the face of impending global challenges.

Testate amoebae (Protozoa) in lakes of the Qinghai-Tibet Plateau: Biodiversity, community structures, and protozoic biosilicification in relation to environmental properties and climate warming

The Qinghai-Tibet Plateau (QTP) is characterized by a vast number of frozen and unfrozen freshwater reservoirs, which is why it is also called "the third pole" of the Earth or "Asian Water Tower". We analyzed testate amoeba (TA) biodiversity and corresponding protozoic biosilicification in lake sediments of the QTP in relation to environmental properties (freshwater conditions, elevation, and climate). As TA are known as excellent bio-indicators, our results allowed us to derive conclusions about the influence of climate warming on TA communities and microbial biogeochemical silicon (Si) cycling. We found a total of 113 TA taxa including some rare and one unknown species in the analyzed lake sediments of the QTP highlighting the potential of this remote region for TA biodiversity. >1/3 of the identified TA taxa were relatively small (<30 μm) reflecting the relatively harsh environmental conditions in the examined lakes. TA communities were strongly affected by physico-chemical properties of the lakes, especially water temperature and pH, but also elevation and climate conditions (temperature, precipitation). Our study reveals climate-related changes in TA biodiversity with consequences for protozoic biosilicification. As the warming trend in the QTP is two to three times faster compared to the global average, our results provide not only deeper insights into the relations between TA biodiversity and environmental properties, but also predictions of future developments in other regions of the world. Moreover, our results provide fundamental data for paleolimnological reconstructions. Thus, examining the QTP is helpful to understand microbial biogeochemical Si cycling in the past, present, and future.

Sunscreens and micro(nano)plastics: Are we aware of these threats to the Egyptian coral reefs?

During a snorkeling trip to Marsa Alam and Hamata (southern Red Sea Riviera, Egypt) I explored the coral reefs and the diverse marine habitats of fish and invertebrate species. The area invites recreational diving and snorkeling, but the beaches are littered with all sorts of solid waste (mainly fragmented plastics). Also, there are no local restrictions on sunscreen use. The development of tourism to the area raises questions about the environmental impact and how its further growth will have on coral reefs. Every year, 1.2 million tourists visit the Red Sea coast (about 3287 tourists per day) and release about 1.7 tons/month of sunscreen into the Red Sea. As an ecologist and editorial board member of Science of the Total Environment, I ask myself how we as scientists can increase public awareness and call for prompt actions to protect the coral reefs. The discussion underlines two major threats to the Egyptian coral reefs: sunscreen use and micro(nano)plastics waste. The discussion closes with possible solutions, future perspectives, and recommendations to protect the coral reefs ecosystem of the Egyptian Red Sea.

Elevated CO2 and nitrogen addition enhance the symbiosis and functions of rhizosphere microorganisms under cadmium exposure

Soil microbes are fundamental to ecosystem health and productivity. How soil microbial communities are influenced by elevated atmospheric carbon dioxide (eCO2) concentration and nitrogen (N) deposition under heavy metal pollution remains uncertain, despite global exposure of terrestrial ecosystems to eCO2, high N deposition and heavy metal stress. Here, we conducted a four year's open-top chamber experiment to assess the effects of soil cadmium (Cd) treatment (10 kg hm-2 year-1) alone and combined treatments of Cd with eCO2 concentration (700 ppm) and/or N addition (100 kg hm-2 year-1) on tree growth and rhizosphere microbial community. Relative to Cd treatment alone, eCO2 concentration in Cd contaminated soil increased the complexity of microbial networks, including the number links, average degree and positive/negative ratios. The combined effect of eCO2 and N addition in Cd contaminated soil not only increased the complexity of microbial networks, but also enhanced the abundance of microbial urealysis related UreC and nitrifying related amoA1 and amoA2, and the richness of arbuscular mycorrhiza fungi (AMF), thereby improving the symbiotic functions between microorganisms and plants. Results from correlation analysis and structural equation model (SEM) further demonstrated that eCO2 concentration and N addition acted on functions and networks differently. Elevated CO2 positively regulated microbial networks and functions through phosphorus (P) and Cd concentration in roots, while N addition affected microbial functions through soil available N and soil organic carbon (SOC) concentration and microbial network through soil Cd concentration. Overall, our findings highlight that eCO2 concentration and N addition make microbial communities towards ecosystem health that may mitigate Cd stress, and provide new insights into the microbiology supporting phytoremediation for Cd contaminated sites in current and future global change scenarios.

Low molecular weight carbohydrate patterns of mangrove macroalgae from different climatic niches under ocean acidification, warming and salinity variation

Ocean acidification has increased due to the enhanced solubility of CO2 in seawater. Mangrove macroalgae in tropical and subtropical coastal regions can benefit from the higher availability of CO2 for photosynthesis and primary production. However, they can be negatively affected by the simultaneously occurring warming and increased salinity in estuaries. Thus, we analyzed the isolated effects of ocean acidification and the interactive effects of increased temperature and salinity on the low molecular weight carbohydrate (LMWC) contents of the mangrove red macroalgae Bostrychia montagnei and Bostrychia calliptera from Brazilian tropical and subtropical populations. Specimens from both climatic niches were tolerant to pH decreased by CO2 enrichment and enhanced their LMWC contents under increased availability of CO2. Specimens from both climatic niches also accumulated their dulcitol and sorbitol contents to cope with warming and salt stress. Nevertheless, temperature of 34 °C was lethal for tropical macroalgae, while 29 °C and 31 °C were lethal for subtropical B. calliptera under salinity of 35. Tropical and subtropical B. montagnei synthesized dulcitol (5-110 mmol kg-1 dry weight) and sorbitol (5-100 mmol kg-1 dry weight) as osmoregulatory, energy and thermal protection compounds, whereas tropical and subtropical B. calliptera synthesized mainly dulcitol (10-210 mmol kg-1 dry weight). Although digeneaside has an energy function in Bostrychia spp., it is not an osmolyte or thermal protection compound. Our data demonstrated that both tropical and subtropical Bostrychia spp. benefit from ocean acidification by CO2 enrichment, increasing their LMWC contents. However, warming and increased salinity in estuaries will be detrimental to them, even they producing protective metabolites. Multifactorial approaches are recommended to investigate whether negative effects of increased temperature and salinity nullify positive effects of ocean acidification on these Bostrychia species/populations.

Evidence for tropospheric ozone effects on rice production in Bangladesh

Although Bangladesh is known to be burdened with elevated tropospheric ozone levels, little is known about its effects on food security. We conducted field experiments in four highly polluted rice growing environments of Bangladesh in three cropping seasons (2020-2022), in which we grew 20 different rice varieties with or without application of the ozone protectant ethylene diurea (EDU). The average daytime ozone concentrations at the study sites during the rice growing seasons ranged from 53 ppb to 84 ppb, with the lowest concentrations occurring in the year 2020. EDU increased rice grain yields significantly by an average of 10.4 % across all seasons and locations, indicating that plants were stressed under ambient ozone concentrations. EDU was effective in distinguishing ozone-tolerant from ozone-sensitive varieties, in which yield increased by up to 21 %. Likewise, the EDU treatment positively affected vegetation indices representing chlorophyll (NDVI), the chorophyll:carotenoid ratio (Lic2), and pigments of the xanthophyll cycle (PRI). Stomatal conductance was increased significantly by an average of around 10 % among all varieties when plants were treated with EDU. In all physiological traits, significant genotype by treatment interactions occurred, indicating that different varieties varied in their responses to ozone stress. Our study demonstrates that rice production in Bangladesh is severely affected by tropospheric ozone, and calls for the breeding of tolerant rice varieties as well as mitigation measures to reduce air pollution.

Prioritize carbon pricing over fossil-fuel subsidy reform

While many climate activist groups enthusiastically advocate for the removal of fossil-fuel subsidies, we argue that this overstates both the climate effectiveness and political feasibility of such a strategy. Through synthesizing information from various global studies, we show that subsidies contribute to a relatively small portion of climate change and local externality problems, likely accounting for around 1%. We further argue that reform of fossil-fuel subsidies is hampered by various political and social factors, more so than the diffusion of carbon pricing. Based on these results, we argue that the far greater problem of unpriced externalities warrants a redirection or expansion of the enthusiasm for subsidy reform toward carbon pricing. This makes sense also as subsidy reform and carbon pricing essentially represent two sides of the same coin since both contribute to climate mitigation by raising fossil-fuel prices.

Water rather than nitrogen availability predominantly modulates soil microbial beta-diversity and co-occurrence networks in a secondary forest

Atmospheric nitrogen (N) deposition and changing precipitation regimes greatly affect the structure and functions of terrestrial ecosystems. However, their impacts on the diversity and assembly of soil microbial communities including bacteria, fungi and protists, remain largely unclear. As part of a six-year field experiment in a secondary forest in a warm temperate and subtropical climate transitional zone in China, we aimed to investigate the responses of soil microbial communities to N addition, increased and decreased precipitation. The results showed that N addition had no effect on soil microbial α- or β-diversity, but reduced the complexity of microbial network. Neither increased nor decreased precipitation influenced soil microbial α-diversity, but decreased precipitation rather than increased precipitation elevated bacterial and protistan community dissimilarities (β-diversity), which could have been largely attributed to species replacement processes through reducing soil water availability. In addition, decreased precipitation weakened microbial complexity and stability, but enhanced the node proportion of protists in the co-occurrence network. Our observations suggest the asymmetric responses of soil microbial β-diversity to increased and decreased precipitation, and underscore that water rather than N availability, especially drought condition, plays a predominant role in modulating soil microbial β-diversity. Moreover, the findings imply that global change can strengthen the importance of soil protists and then reshape microbial assembly in forests.

Effectiveness of two mechanical shrub removal treatments for restoring sub-alpine grasslands colonized by re-sprouting woody vegetation

The extent of European sub-alpine grasslands and their associated ecosystem services are decreasing due to woody plant encroachment. Commonly used methods of woody vegetation suppression like prescribed burning or clearcutting usually cause little damage to belowground bud-banks, offering poor results against re-sprouting shrubs. In this study, we assessed the effects on vegetation and soil properties of two mechanical shrub removal methods for restoring sub-alpine grasslands colonized by the re-sprouting shrub Rosa sp. in the Central Spanish Pyrenees: a commonly used method based on clearcutting (Clearcutting); and a non-previously assessed method based on pulling shrubs off the soil to remove both the aerial and belowground bud-banks (Uprooting). We set a parallel experiment to test whether or not clustering Rosa sp. debris generated in Uprooting (which held many mature fruits) at certain grassland locations may promote colonization of new grassland spots by Rosa sp. seedlings. By the end of the study period, vegetation composition and structure was more similar to the reference grassland in Uprooting than in Clearcutting. Indeed, woody vegetation cover was 71 % smaller in Uprooting than in Clearcutting three years after shrub removal. Nevertheless, by the end of the study period, chemical and microbiological soil properties were slightly more similar to the reference grassland in Clearcutting than in Uprooting. Additionally, the results of our study showed that clustering unusually high number of mature fruits of Rosa sp. at certain grassland locations increased shrub seedling colonization in comparison with other areas of the reference grassland, indicating that operational planning needs to take into account shrub phenology. In conclusion, our work showed that Uprooting may be a useful tool for land managers aiming to restore sub-alpine grasslands colonized by re-sprouting shrubs, though it is advisable using it for scatter shrub patches to prevent significant medium to long-term soil disturbance at landscape scale.

Trace metal level variation under strong wind conditions and sediment resuspension in the waters of a coastal lagoon highly impacted by mining activities

The levels of metals in the waters of the Mar Menor lagoon are higher in the southern than in the northern zone both in the dissolved (As: 1.78 μg L-1 north vs 1.86 μg L-1 south; Cd: 0.020 μg L-1 vs 0.055 μg L-1; Pb: 0. 686 μg L-1 vs 2.714 μg L-1; Zn: 3.06 μg L-1 vs 10.2 μg L-1) as in the particulate fraction (As: 13.6 μg g-1 north vs 27.3 μg g-1 south; Cd: 0.510 μg g-1 vs 2.11 μg g-1; Pb: 146 μg g-1 vs 575 μg g-1; Zn: 266 μg g-1 vs 729 μg g-1). This difference is associated to the influence of historical and recent inputs from the Sierra Minera Cartagena -La Unión located south of the lagoon. Strong winds cause sediment resuspension in this shallow lagoon, increasing metal levels in the dissolved (twofold) and especially in the particulate fraction (threefold) because the resuspended sediments are rich in metals. Distribution among dissolved and particulate fraction is determined by the chemistry of each element and salinity. This increase causes the levels to reach limits very close to those established by the Water Framework Directive, especially in the case of lead, whose annual average level of 1.23 μg L-1 is very close to the 1.3 μg L-1 established in the Directive. Therefore, slight change in environmental variables could make Pb levels to exceed legal limits. Future work should focus on investigating how unique environmental events, enhanced by global change, affect metal cycles in highly anthropised coastal areas.

High vulnerability of coastal wetlands in Chile at multiple scales derived from climate change, urbanization, and exotic forest plantations

Coastal wetlands are considered one of the most vulnerable ecosystems worldwide; the ecosystem services they provide and the conservation of their biodiversity are threatened. Despite the high ecological and socioenvironmental value of coastal wetlands, regional and national vulnerability assessments are scarce. In this study we aimed to assess the vulnerability of coastal wetlands in Chile from 18°S to 42°S (n = 757) under a multiscale approach that included drivers associated with climate change and land cover change. We assessed multiple drivers of vulnerability at three spatial scales (10 m, 100 m, and 500 m) by analyzing multiple remote sensing data (16 variables) on land cover change, wildfires, climatic variables, vegetation functional properties, water surface and importance for biodiversity. We constructed a multifactorial vulnerability index based on the variables analyzed, which provided a map of coastal wetland vulnerability. Then we explored the main drivers associated with the vulnerability of each coastal wetland by performing a Principal Components Analysis with Agglomerative Hierarchical Clustering, which allowed us to group coastal wetlands according to the drivers analyzed. We found that 42.6 ± 9.2 % of the coastal wetlands evaluated have high or very high vulnerability, with higher vulnerability at the 500 m scale (51.4 %). We identified four groups of coastal wetlands: two located in central Chile, mainly affected by climate change-associated drivers (41.9 ± 2.1 %), and one in central Chile which is affected by land cover change (52.8 ± 6.2 %); the latter has a lower vulnerability level. The most vulnerable coastal wetlands were located in central Chile. Our results present novel findings about the current vulnerability of coastal wetlands, which could be validated by governmental institutions in field campaigns. Finally, we believe that our methodological approach could be useful to generate similar assessments in other world zones.

Stable isotopes and a changing world

The measurement of naturally occurring stable isotope ratios of the light elements (C, N, H, O, S) in animal tissues and associated organic and inorganic fractions of associated environments holds immense potential as a means of addressing effects of global change on animals. This paper provides a brief review of studies that have used the isotope approach to evaluate changes in diet, isotopic niche, contaminant burden, reproductive and nutritional investment, invasive species and shifts in migration origin or destination with clear links to evaluating effects of global change. This field has now reached a level of maturity that is impressive but generally underappreciated and involves technical as well as statistical advances and access to freely available R-based packages. There is a need for animal ecologists and conservationists to design tissue collection networks that will best answer current and anticipated questions related to the global change and the biodiversity crisis. These developments will move the field of stable isotope ecology toward a more hypothesis driven discipline related to rapidly changing global events.

Bioavailable iron concentrations regulate phytoplankton growth and bloom formation in low-nutrient lakes

The growth of phytoplankton in lakes is thought to be primarily controlled by macronutrient concentrations, but the availability of trace metal micronutrients, such as iron (Fe), are increasingly recognised as important regulators of lake primary production. This study evaluates the role of Fe in regulating phytoplankton growth in lakes of different nutrient status in New Zealand. The results of this unique year-long study, combining highly sensitive trace metal concentration analysis of waters and particulates with advanced trace metal bioavailability and speciation modelling, constrains thresholds for bioavailable Fe and colloidal Fe of 0.8 nmol·L-1 and 30 nmol·L-1, respectively, below which phytoplankton growth-limitation occurs. These thresholds specifically control diatom bloom formation and termination in lakes, thereby exerting a strong influence on freshwater carbon sequestration, given the dominance of diatoms in lake bloom assemblages. Importantly, potentially toxic cyanobacteria thrived only after events of bottom water anoxia, when additional dissolved Fe in concentrations ≥4 nmol·L-1 was released into the water column. These new thresholds for bioavailable and colloidal Fe offer the potential to manage micronutrient levels in lakes for the purpose of regulating algal bloom formation and carbon sequestration, while at the same time, suppressing the formation of harmful cyanobacterial blooms.

Anthropogenic effects on global soil nitrogen pools

The amount of nitrogen stored in terrestrial soils, its "nitrogen pool", moderates biogeochemical cycling affecting primary productivity, nitrogen pollution and even carbon budgets. The soil nitrogen pools and the transformation of nitrogen forms within them are heavily influenced by environmental factors including anthropogenic activities. However, our understanding of the global distribution of soil nitrogen with respect to anthropogenic activity and human land use remains unclear. We constructed a meta-analysis from a global sampling, in which we compare soil total nitrogen pools and the driving mechanisms affecting each pool across three major classifications of human land use: natural, agricultural, and urban. Although the size of the nitrogen pool can be similar across natural, agricultural and urban soils, the ecological and human associated drivers vary. Specifically, the drivers within agricultural and urban soils as opposed to natural soils are more complex and often decoupled from climatic and soil factors. This suggests that the nitrogen pools of those soils may be co-moderated by other factors not included in our analyses, like human activities. Our analysis supports the notion that agricultural soils act as a nitrogen source while urban soils as a nitrogen sink and informs a modern understanding of the fates and distributions of anthropogenic nitrogen in natural, agricultural, and urban soils.

Leaf trait responses to global change factors in terrestrial ecosystems

Global change influences plant growth by affecting plant morphology and physiology. However, the effects of global change factors vary based on the climate gradient. Here, we established a global database of leaf traits from 192 experiments on elevated CO2 concentrations (eCO2), drought, N deposition, and warming. The results showed that the leaf mass per area (LMA) significantly increased under eCO2 and drought conditions but decreased with N deposition, whereas eCO2 levels and drought conditions reduced stomatal conductance and increased and decreased photosynthetic rates, respectively. Leaf dark respiration (Rd) increased in response to global change, excluding N deposition. Leaf N concentrations declined with eCO2 but increased with N deposition. Leaf area increased with eCO2, N deposition, and warming but decreased with drought. Leaf thickness increased with eCO2 but decreased with warming. eCO2 and N deposition enhanced plant water-use efficiency (WUE), eCO2 and warming increased photosynthetic N-use efficiency (PNUE), while N fertilization reduced PNUE significantly. eCO2 produced a positive relationship between WUE and PNUE, which were limited under drought but increased in areas with high humidity and high temperature. Trade-offs were observed between WUE and PNUE under drought, N deposition, and warming. These findings suggest that the effects of global change factors on plants can be altered by complex environmental changes; moreover, diverse plant water and nutrient strategy responses can be interpreted against the background of their functional traits.

Gadiform species display dietary shifts in the Celtic Sea

Global changes, through their impacts on ecosystem trophic structures, are behind regime shifts and cascading effects, and could result in the reorganization of whole ecosystems. The Celtic Sea is a temperate sea at risk of the above because of the interplay between climate change and fisheries. This sea has only displayed slight changes in species diversity between the late 20th century and the present day. However, this apparent stability in species diversity could be hiding structural transformations, including the rearrangement of trophic relationships. Historical stomach content database offers the opportunity to investigate changes in ecosystem trophic structure. Based on such database, this study explored shifts in the feeding habits of gadiform species in the Celtic Sea in the 1980s, 1990s, and 2010s. To this end, it examined dietary generalism and composition for four top predator fish species. During the target period, generalists maintained their diets, while specialists adopted more generalist diets. There were also decreases in frequencies of occurrence of certain fishes within the diets of gadiform species. These recent changes in trophic structure organization have likely been caused by the influence of global changes on both top-down and bottom-up processes that occurred in the Celtic Sea.

Distinct patterns of the soil and phyllosphere antibiotic resistome in natural forest ecosystems under an altitudinal gradient

Warming affects microbial functioning of soil and the phyllosphere across global ecosystems. However, little is known about the impact of increasing temperature on antibiotic resistome profiles in natural forests. To address this issue, we investigated antibiotic resistance genes (ARGs) in both soil and the plant phyllosphere using an experimental platform established in a forest ecosystem that delivers a temperature difference of 2.1 °C along an altitudinal gradient. Principal Coordinate Analysis (PCoA) showed that there were significant differences in the composition of soil and plant phyllosphere ARGs at different altitudes (P = 0.001). The relative abundance of phyllosphere ARGs and mobile genetic elements (MGEs) and soil MGEs increased with temperature. More resistance gene classes increased in abundance in the phyllosphere (10 classes) than soil (2 classes), and a Random Forest model analysis suggested that phyllosphere ARGs were more sensitive to temperature change than soil. Increasing temperature as a direct consequence of an altitudinal gradient, and the relative abundance of MGEs were the main drivers that shaped the profiles of ARGs in the phyllosphere and soil. Biotic and abiotic factors affected phyllosphere ARGs indirectly via MGEs. This study enhances our understanding of the influence of altitude gradients on resistance genes in natural environments.

Gene co-expression networks unravel the molecular responses of freshwater hydrophytes to combined stress of salinity and cadmium

Salinization in freshwater lakes is becoming a serious global environmental problem, especially in lakes of plateaus such as south-western plateau of China. However, limited information is available about the molecular response of freshwater hydrophytes to salinity under multiple stress. In the present study, a weighted gene co-expression network (WGCNA) was used to identify the modules of co-expressed genes in the physiological and biochemical indicators of Pistia stratiotes to determine its molecular response to salinity (NaCl) alone and when combined with cadmium (Cd). The physiological and biochemical indicators showed that P. stratiotes improved its salt tolerance by enhancing photosynthetic abilities, reducing oxidative stress, and inducing osmoprotectant generation. Morever, addition of NaCl reduced the Cd accumulation in P. stratiotes. Transcriptome and WGCNA analysis revealed that the pathways of alpha-linolenic acid metabolism, ribosomal, flavonoid biosynthesis, and phenylpropanoid biosynthesis were significantly enriched in both treatments. Genes associated with photosynthesis-antenna proteins, nitrogen metabolism, and the acid cycle pathways were only expressed under salinity stress alone, while the proteasome pathway was only significantly enriched in the combined salinity and Cd treatment. Our findings provide novel insights into the effects of salinization on aquatic plants in freshwater ecosystems and the management of aquatic ecosystems under global change.

Frontal changes in medium-sized glaciers in Sikkim, India during 1988-2018: Insights for glacier-climate synthesis over the Himalaya

The study assesses terminus retreat of medium-sized glaciers (1988-2018) using geospatial dataset and field study in Sikkim which is under the direct influence of the Indian SW monsoon. It also explores the causes of intra-regional and inter-regional diverse patterns of glacier retreat under the purview of topographical and climatic factors to develop a glacier-climate synthesis over the region. Glaciers have retreated in a range from 63.9 to 3.9 m yr-1 and lost a total area of ∼2.53% (0.08% yr-1) in the study area. The intra-regional heterogeneity in glaciers retreat seems to be caused by topographical factors in the study area. A comparison of glacier retreats with other parts of the Himalayas reveals a declining gradient from the northwest to the eastern Himalayas, broadly. This inter-regional disparity in the retreat rate seems to be caused by existing climatic regimes over different parts of the Himalayas. The results help to comprehend the glacier-climate synthesis over the Himalayan region.

Effects of micro(nano)plastics on soil nutrient cycling: State of the knowledge

The ecological impacts of micro(nano)plastics (MNPs) have attracted attention worldwide because of their global occurrence, persistence, and environmental risks. Increasing evidence shows that MNPs can affect soil nutrient cycling, but the latest advances on this topic have not systematically reviewed. Here, we aim to present the state of knowledge about the effects of MNPs on soil nutrient cycling, particularly of C, N, and P. Using the latest data, the present review mainly focuses on three aspects, including (1) the effects and underlying mechanisms of MNPs on soil nutrient cycling, particularly of C, N and P, (2) the factors influencing the effects of MNPs on soil nutrient cycling, and (3) the knowledge gaps and future directions. We conclude that MNPs can alter soil nutrient cycling via mediating soil nutrient availability, soil enzyme activities, functional microbial communities, and their potential ecological functions. Furthermore, the effects of MNPs vary with MNPs characteristics (i.e., polymeric type, size, dosage, and shape), chemical additives, soil physicochemical conditions, and soil biota. Considering the complexity of MNP-soil interactions, multi-scale experiments using environmental relevant MNPs are required to shed light on the effects of MNPs on soil nutrients. By learning how MNPs influence soil nutrients cycles, this review can guide policy and management decisions to safeguard soil health and ensure sustainable agriculture and land use practices.

Bird diversity along an urban to rural gradient in large tropical cities peaks in mid-level urbanization

The gradient from natural to urban areas strongly associates with the structure of avian communities over that gradient. Most research on urban birds is from temperate areas and knowledge from tropical Southeast Asia is lacking. We examined bird species diversity, relative abundance, and species composition along an urban to rural gradient in three Myanmar cities, and assessed potential environmental factors responsible for the changes. We counted birds within 40 point-count sites with 50-m fixed-radius in three large cities of Myanmar, namely Mandalay, Mawlamyine, and Myeik. We distinguished four urban habitat types (Downtown-urban, University Campus-suburban, Paddy Field-agriculture, Hill-forest). We classified all species into migrant or resident and into major feeding groups and related with several environmental parameters such as 'impervious surface'. We counted 5,423 individuals of 103 species with roughly equal species diversity between the three cities. Rock Pigeon (Columba livia) was the most frequent species. The species composition differed significantly between the four major habitat types. Omnivores were more abundant in the city center than all other functional groups. Interestingly, insectivores were also predominant in the city center. In addition, more generalist' species occurred towards the city center compared to the periphery, indicating that the periphery has increased relevance for specialized birds. We found some marked differences in species composition between the three cities of Mandalay, Mawlamyine, and Myeik. Additionally to species composition, species diversity and relative abundance differed significantly between each of the four major habitat types in all three cities.

Characterization and expression of heat shock and immune genes in natural populations of Prodiamesa olivacea (Diptera) exposed to thermal stress

This paper characterizes the heat stress response (HSR) and explores the impact of temperatures on the immune response of larvae from two chironomid species, Prodiamesa olivacea and Chironomus riparius. Genes involved in crucial metabolic pathways were de novo identified in P. olivacea: Hsp27, Hsp60, Hsp70, Hsc70, Cdc37, and HSF for the heat stress response (HSR) and TOLL, PGRP, C-type lectin, and JAK/hopscotch for the immune system response (ISR). Quantitative real-time PCR was used to evaluate the expression levels of the selected genes in short-term treatments (up to 120') at high temperatures (35 °C and 39 °C). Exposing P. olivacea to elevated temperatures resulted in HSR induction with increased expression of specific heat shock genes, suggesting the potential of HSPs as early indicators of acute thermal stress. Surprisingly, we found that heat shock represses multiple immune genes, revealing the antagonist relation between the heat shock response and the innate immune response in P. olivacea. Our results also showed species-dependent gene responses, with more significant effects in P. olivacea, for most of the biomarkers studied, demonstrating a higher sensitivity in this species to environmental stress conditions than that of C. riparius. This work shows a multi-species approach that enables a deeper understanding of the effects of heat stress at the molecular level in aquatic dipterans.

Fate of microplastics under the influence of climate change

Plastic pollution and climate change are two major environmental focuses. Having the forming potential due to ambient plastic pollution, the environmental fate of microplastics shall be inevitably impacted by global warming. This manuscript discusses the destiny of environmental microplastics and characterizes their fate considering the framework of the planetary boundary. The major routes for microplastic discharge include the release of microplastic stored in the ice into the sea when the ice melts as a result of global temperature increase, flushing of the plastic/microplastic debris from the shorelines into the adjacent water bodies as a result of increased rainfall, redistribution of the microplastics away from the source of plastic debris as a result of increased wind, and accumulation of microplastics in the soil as a result of drought. A perspective on the impact of climate change and microplastic pollution on aquatic and soil organisms was discussed as well.

Temperature drives elevational diversity patterns of different types of organisms in Qinghai-Tibetan Plateau wetlands

The spatial pattern and driving mechanism of biodiversity along elevational gradients are key topics in ecology. However, it is still unclear whether the multidimensional diversity of different types of organisms shows a similar response to elevation changes. Here, we measured the species and phylogenetic diversity of plants, bacteria, fungi, and microbial functional groups (nitrifiers, denitrifiers, methanogens, and methanotrophs) in 36 wetland sites on the Qinghai-Tibetan Plateau. The results showed that both species and phylogenetic diversity of plants, bacteria, and fungi exhibited a significant elevational gradient, in direct contrast to no significant diversity changes observed for denitrifiers, methanogens, and methanotrophs along the same altitude gradient. Our findings suggest that elevation and temperature were more likely to associate with the diversity of plants, bacteria, and fungi than the diversity of microbial functional groups, with important implications for assessing the effect of ongoing climate warming on biodiversity in Qinghai-Tibetan alpine wetlands.

Characterizing the 2020 summer floods in South China and effects on croplands

Floods occur more frequently in the context of climate change; however, flood monitoring capacity has not been well established. Here, we used a synergic mapping framework to characterize summer floods in the middle and lower reaches of the Yangtze River Plain and the effects on croplands in 2020, from both flood extent and intensity perspectives. We found that the total flood extent was 4936 km² from July to August, and for flood intensity, 1658, 1382, and 1896 km² of areas experienced triple, double, and single floods. A total of 2282 km² croplands (46% of the flooded area) were inundated mainly from Poyang and Dongting Lake Basins, containing a high ratio of moderate damage croplands (47%). The newly increased flooding extent in 2020 was 29% larger than the maximum ever-flooded extent in 2015-2019. This study is expected to provide a reference for rapid regional flood disaster assessment and serving mitigation.

The spatiotemporal extent of the Green Sahara during the last glacial period

The Sahara Desert, one of today's most inhospitable environments, has known periods of enhanced precipitation that supported pre-historic humans. However, the Green Sahara timing and moisture sources are not well known due to limited paleoclimate information. Here, we present a multi-proxy (δ¹⁸O, δ¹³C, Δ¹⁷O, and trace elements) speleothem-based climate record from Northwest (NW) Africa. Our data document two Green Sahara periods during Marine Isotope Stage (MIS) 5a and the Early to Mid-Holocene. Consistency with paleoclimate records across North Africa highlights the east-west geographical extent of the Green Sahara, whereas millennial-scale North Atlantic cooling (Heinrich) events consistently resulted in drier conditions. We demonstrate that an increase in westerly-originating winter precipitation during MIS5a resulted in favorable environmental conditions. The comparison of paleoclimate data with local archaeological sequences highlights the abrupt climate deterioration and the decline in human density in NW Africa during the MIS5-4 transition, which suggests climate-forced dispersals of populations, with possible implications for pathways into Eurasia.

Changes in Coleopteran assemblages over a successional chronosequence in a Mexican tropical dry forest

Coleopterans are the most diverse animal group on Earth and constitute good indicators of environmental change. However, little information is available about Coleopteran communities' responses to disturbance and land-use change. Tropical dry forests have undergone especially extensive anthropogenic impacts in the past decades. This has led to mosaic landscapes consisting of areas of primary forest surrounded by pastures, agricultural fields and secondary forests, which negatively impacts many taxonomic groups. However, such impacts have not been assessed for most arthropod groups. In this work, we compared the abundance, richness and diversity of Coleopteran morphospecies in four different successional stages in a tropical dry forest in western Mexico, to answer the question: How do Coleopteran assemblages associate with vegetation change over the course of forest succession? In addition, we assessed the family composition and trophic guilds for the four successional stages. We found 971 Coleopterans belonging to 107 morphospecies distributed in 28 families. Coleopteran abundance and richness were greatest for pastures than for latter successional stages, and the most abundant family was Chrysomelidae, with 29% of the individuals. Herbivores were the most abundant guild, accounting for 57% of the individuals, followed by predators (22%) and saprophages (21%) beetles. Given the high diversity and richness found throughout the successional chronosequence of the studied tropical dry forest, in order to have the maximum number of species associated with tropical dry forests, large tracts of forest should be preserved so that successional dynamics are able to occur naturally.

Does pollinator dependence decrease along elevational gradients?

Plants have long been thought to be less dependent on pollinators for seed production at higher elevations due to adverse pollination environments. However, recent research has yet to consistently support the generality of this expectation. In this study, we asked whether pollinator dependence decreases along an elevational gradient and how it varies with various reproductive traits. To answer these questions, we quantified pollinator-plant associations and various reproductive traits for 112 flowering plants spanning a large elevational gradient (990-4260 m a.s.l.) in the Qinghai-Tibet Plateau. We found that flowering plants in the Qinghai-Tibet Plateau region are highly dependent on pollinators for seed production (76.2% of seed production was contributed by animal pollinators and 44.6% of plants would produce no seed without pollinator visitation). Contrary to our expectation, there was no significant elevational gradient in pollinator dependence index. Although the pollinator dependence index was not significantly correlated with pollen limitation, flower size, floral longevity, or reward type, it was correlated with compatibility status and flowering time. These findings indicate that pollinator dependence does not decrease along an elevational gradient in the Qinghai-Tibet Plateau. Our study also highlights the severe vulnerability of flowering plant seed production to pollinator declines under global change in the Qinghai-Tibet Plateau region, particularly for early-flowering or self-incompatible plants growing at higher elevations (e.g., subnival belt).

Soil nematode assemblages respond to interacting environmental changes

Multi-factor experiments suggest that interactions among environmental changes commonly influence biodiversity and community composition. However, most field experiments manipulate only single factors. Soil food webs are critical to ecosystem health and may be particularly sensitive to interactions among environmental changes that include soil warming, eutrophication, and altered precipitation. Here, we asked how environmental changes interacted to alter soil nematode communities in a northern Chihuahuan Desert grassland. Factorial manipulations of nitrogen, winter rainfall, and nighttime warming matched predictions for regional environmental change. Warming reduced nematode diversity by 25% and genus-level richness by 32%, but declines dissipated with additional winter rain, suggesting that warming effects occurred via drying. Interactions between precipitation and nitrogen also altered nematode community composition, but only weakly affected total nematode abundance, indicating that most change involved reordering of species abundances. Specifically, under ambient precipitation, nitrogen fertilizer reduced bacterivores by 68% and herbivores by 73%, but did not affect fungivores. In contrast, under winter rain addition, nitrogen fertilization increased bacterivores by 95%, did not affect herbivores, and doubled fungivore abundance. Rain can reduce soil nitrogen availability and increase turnover in the microbial loop, potentially promoting the recovery of nematode populations overwhelmed by nitrogen eutrophication. Nematode communities were not tightly coupled to plant community composition and may instead track microbes, including biocrusts or decomposers. Our results highlight the importance of interactions among environmental change stressors for shaping the composition and function of soil food webs in drylands.

Impact of global urban expansion on the terrestrial vegetation carbon sequestration capacity

Continuous urban expansion has a negative impact on the potential of terrestrial vegetation. Till now, the mechanism of such impact remains unclear, and there have been no systematic investigations. In this study, we design a theoretical framework by laterally bridging urban boundaries to explain the distress of regional disparities and longitudinally quantify the impacts of urban expansion on net ecosystem productivity (NEP). The findings demonstrate that global urban expanded by 37.60 × 10⁴ km² during 1990-2017, which is one of the causes of vegetation carbon loss. Meanwhile, certain climatic changes (e.g., rising temperature, rising CO₂, and nitrogen deposition) caused by urban expansion indirectly boosted vegetation carbon sequestration potential through photosynthetic enhancement. The direct decrease in NEP due to the urban expansion (occupying 0.25 % of the Earth's land area) offsets the 1.79 % increase due to the indirect impact. Our findings contribute to a better understanding of the uncertainty associated with urban expansion towards carbon neutrality and provide a scientific reference for sustainable urban development worldwide.

Acclimation in intertidal animals reduces potential pathogen load and increases survival following a heatwave

Intertidal animals can experience intense heat during a heatwave, leading to mortality. The causes of death for intertidal animals following heatwaves have often been attributed to a breakdown in physiological processes. This, however, contrasts with research in other animals where heatwave mortality is attributed to existing or opportunistic diseases. We acclimated intertidal oysters to four treatment levels, including an antibiotic treatment, and then exposed all treatments to a 50°C heatwave for 2 h, replicating what can be experienced on Australian shorelines. We found that both acclimation and antibiotics increased survival and reduced the presence of potential pathogens. Non-acclimated oysters had a significant shift in their microbiome, with increasing abundances of bacteria from the Vibrio genera, including known potential pathogens. Our results demonstrate that bacterial infection plays a pivotal role in post-heatwave mortality. We anticipate these findings to inform the management of aquaculture and intertidal habitats as climate change intensifies.

Integrated FT-ICR MS and metabolome reveals diatom-derived organic matter by bacterial transformation under warming and acidification

Bacterial transformation and processing of diatom-derived organic matter (OM) is extremely important for the cycling of production and energy in marine ecosystems; this process contributes to the production of microbial food webs. In this study, a cultivable bacterium (Roseobacter sp. SD-R1) from the marine diatom Skeletonema dohrnii were isolated and identified. A combined Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS)/untargeted metabolomics approach was used to synthesize the results of bacterial transformation with dissolved OM (DOM) and lysate OM (LOM) under warming and acidification through laboratory experiments. Roseobacter sp. SD-R1 had different preferences for the conversion of molecules in S. dohrnii-derived DOM and LOM treatments. The effects of warming and acidification contribute to the increased number and complexity of molecules of carbon, hydrogen, oxygen, nitrogen, and sulfur after the bacterial transformation of OM. The chemical complexity generated by bacterial metabolism provides new insights into the mechanisms that shape OM complexity.

Does mangrove vegetation structure reflect human utilization of ecosystem goods and services?

Many coastal communities in developing countries depend on mangrove ecosystem services (ES). A combination of anthropogenic and environmental stresses threatens mangroves globally. This study at the Ankobra catchment communities in Ghana focused on the relation between ES utilization and mangrove forest structure. Through vegetation survey, we observed significant effects of selective logging, branch cutting, density of Acrostichum aureum, and water stress on tree stocking and sapling densities. We observed through interviews in five communities that about 98% and 88% of mangrove wood harvested are used for fuelwood and construction respectively. The vegetation structure of the forest areas receiving high harvesting pressures was less complex, with lower tree and sapling density, as well as lower seed-bearing trees than less-disturbed areas. Existing mangrove harvesting regulations are compromised to accommodate the needs of the surrounding communities. Recognizing these impacts is important to improve management decisions, address community needs, and reduce pressure on mangroves.