How interactions between temperature and resources scale from populations to communities in microbes

This study involves investigation on the seasonal and longitudinal effects of the trout farm on the Crnica River on the chemical composition of water and sediment, structure, and composition of the macrozoobenthos communities and molecular biomarkers of oxidative stress, such as activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and the amount of total glutathione (GSH) in larvae of Ephemera danica (Müller 1764). To analyze the changes in the composition of the macrozoobenthos community caused by fish farm effluents, several macrozoobenthos indices were used. The potential impact of trout farm effluents on the macrozoobenthos community was evident at the CR2 sampling site, where the saprobic index (SI) reached its highest value and the BMWP (Biological Monitoring Working Party) score was at its lowest. This indicates that the fish pond had negative effect on water quality and reduced the diversity of the macrozoobenthos community. All components of antioxidant defense showed minimum activity in autumn and maximum in summer. The most sensitive biomarker to the effects of the trout farm effluents was the change in the GPx activity. This biomarker showed higher sensitivity in relation to most sensitive macrozoobenthos indices − SI, BMWP, and MBMWPPO (Modified Biological Monitoring Working Party Present Only). Seasonal changes in abiotic factors were more pronounced than changes in abiotic factors along the sites, which we consider to be influenced by the fish pond and refer to as longitudinal changes. Therefore, the seasonal changes in environmental abiotic factors had a greater impact than the fish farm on the examined biomarkers and the structural and compositional parameters of the macrozoobenthos communities. Regarding seasons, most pronounced farm effects could be seen in autumn, when synergistic impact of pollutants, such as NO2– and NH3, and abiotic parameters of water and sediment (Cr and Ni) had a negative effect on the macrozoobenthos community, but primarily on the components of the antioxidant defense in E. danica which caused decrease in the number of specimens in autumn, as much as 10-fold less than in summer.

Mofettes or natural CO2 springs release large amounts of geogenic CO2 at ambient temperature, leading to long-term soil hypoxia in these extreme ecosystems. Thus, they can serve as natural long-term experiments in ecology and evolution and other environmental studies, providing stable long-term changes in abiotic factors that are most pronounced in mofette soils. This paper reviews basic research on rhizosphere processes, soil microbial communities, and microbial diversity in mofettes, focusing on reports describing the effects of altered soil gas regimes on root respiration and the diversity and community structure of archaea, bacteria, and fungi in soil. Furthermore, an insight into possible applications of mofette ecosystems is given. For more than 20 years, mofettes have provided new insights into the importance of long-term changes in abiotic environmental factors in regulating soil biodiversity, serving as a model for extreme ecosystems. Mofettes provide an innovative approach to the study of many ecological processes that occur slowly and, therefore, require extensive and lengthy observations and experiments, acting as a space-for-time substitution. Previous studies in mofettes around the world have determined plant responses to elevated CO2 concentrations over multiple generations, described new species of collembolans and yeasts, and identified stable patterns in microbial communities describing specific acidophilic and methanogenic consortia of soil archaea and bacteria, as well as stable communities of plant symbiotic arbuscular mycorrhizal fungi. As the development of high-throughput molecular techniques has accelerated rapidly in the last decade, mofettes now serve more than ever as a natural long-term experimental system to study soil and rhizosphere ecology and contribute to further research on long-term ecological and evolutionary processes that are crucial for understanding past evolutionary events, managing future ecosystems, and predicting ecological responses to global change. Some recent developments target the specific geological and biological characteristics of these extreme ecosystems, including in terms of applications related to environmental impact assessment of carbon capture and storage systems, as well as conservation status, tourism, culture and education, i.e., broader ecosystem services of mofettes, which are addressed in this review together with basic research on soil biodiversity.

Light-related leaf traits variation is structured among individuals and within individuals in a latitudinal pattern from the equator (high variation) toward the poles (lower variation). Intraspecific variation in leaf functional traits can play a crucial role at multiple ecological scales. However, our understanding of leaf functional trait variation (FV) across spatial scales is limited. Moreover, the influence of FV in specific responses to the environment remains poorly assessed. We investigated FV across multiple nested ecological scales in a set of leaf traits related to light interception and photosynthetic performance in eight populations of Olea europaea trees distributed over a wide latitudinal gradient (~60°). Specifically, we measured SLA, leaf shape, leaf’s spatial position (leaf angles) and leaf’s potential exposure to direct sunlight (silhouette area of the leaf blade and silhouette to area ratio of the leaf blade). The variability in leaf traits revealed two main patterns depending on the considered trait. Differences among sites absorbed >50% of the trait variation related to leaf shape and structure. Conversely, traits related to leaf position and exposure to direct light varied mostly within individuals among crown positions. The variation within trees for multiple traits ranged from 4 to 14%. Trees of equatorial populations had wider, thinner and more exposed leaves to direct light than trees of the remaining populations. The FV for multiple leaf traits at the tree scale was spatially structured within the tree crown and was higher for populations at the equator than for populations located in other latitudes. The differences among traits and scales in the magnitude of FV revealed a complex structure that could be linked to local adaptation.

Climate change influences marine environmental conditions and is projected to increase future environmental variability. In the North Atlantic, such changes will affect the behavior and spatiotemporal distributions of large pelagic fish species (i.e., tunas, billfishes, and sharks). Generally, studies on these species have focused on specific climate-induced changes in abiotic factors separately (e.g., water temperature) and on the projection of shifts in species abundance and distribution based on these changes. In this review, we consider the latest research on spatiotemporal effects of climate-induced environmental changes to HMS’ life history, ecology, physiology, distribution, and habitat selection, and describe how the complex interplay between climate-induced changes in biotic and abiotic factors, including fishing, drives changes in species productivity and distribution in the Northwest Atlantic. This information is used to provide a baseline for investigating implications for management of pelagic longline fisheries and to identify knowledge gaps in this region. Warmer, less oxygenated waters may result in higher post-release mortality in bycatch species. Changes in climate variability will likely continue to alter the dynamics of oceanographic processes regulating species behavior and distribution, as well as fishery dynamics, creating challenges for fishery management. Stock assessments need to account for climate-induced changes in species abundance through the integration of species-specific responses to climate variability. Climate-induced changes will likely result in misalignment between current spatial and temporal management measures and the spatiotemporal distribution of these species. Finally, changes in species interactions with fisheries will require focused research to develop best practices for adaptive fisheries management and species recovery.

Predation often deviates from the law of mass action: many micro‐ and meso‐scale experiments have shown that consumption saturates with resource abundance, and decreases due to interference between consumers. But does this observation hold at macro‐ecological scales, spanning many species and orders of magnitude in biomass? If so, what are its consequences for large‐scale ecological patterns and dynamics? We perform a meta‐analysis of predator–prey pairs of mammals, birds and reptiles, and show that total predation rates appear to increase, not as the product of predator and prey densities following the Lotka–Volterra (mass action) model, but rather as the square root of that product. This suggests a phenomenological power‐law expression of the effective cross‐ecosystem predation rate. We discuss whether the same power‐law may hold dynamically within an ecosystem, and assuming that it does, we explore its consequences in a simple food chain model. The empirical exponents fall close to the boundary between regimes of donor and consumer limitation. Exponents on this boundary are singular in multiple ways. First, they maximize predator abundance and some stability metrics. Second, they create proportionality relations between biomass and productivity, both within and between trophic levels. These intuitive relations do not hold in general in mass action models, yet they are widely observed empirically. These results provide evidence of mechanisms limiting predation across multiple ecological scales. Some of this evidence was previously associated with donor control, but we show that it supports a wider range of possibilities, including forms of consumer control. As limiting consumption counter‐intuitively allows larger populations, it is worthwhile to reconsider whether the observed predation rates arise from microscopic mechanisms, or could hint at selective pressure at the population level.

Climate warming can stimulate soil microbial degradation of organic matter, leading to increases in both microbial growth and CO₂ release into the atmosphere. If microbial growth or respiration outpaces the other in response to warming, it can alter the carbon-use efficiency, potentially leading to either increased carbon storage or release. Understanding the temperature-adaptive responses of soil decomposer microbes is thus essential, as they may significantly influence the balance of C between soil and atmosphere. In this study, we used a “space-for-time” substitution to test the impact of environmental temperature change on microbial carbon cycling in soils from a tropical elevation gradient in Chirripó, Costa Rica, using an in situ reciprocal 7-month transplant experiment to low and high elevation. We hypothesized (H1) that the transplantation of samples will shift microbial thermal traits. Specifically, we expected cold transplants to shift the traits of microbes from warm soils toward cool-adapted traits, while warm transplants would shift the traits of microbes from cold soils toward warm-adapted traits. Additionally, warming accelerates microbial use of organic matter (OM), depleting high-quality soil carbon, while cooling slows it, preserving carbon quality. This shift in carbon quality should increase microbial growth in warm soils under cold conditions and decrease growth in cold soils under warm conditions at a standard temperature (H2).  Furthermore, based on the carbon-quality temperature (CQT) hypothesis we expected that the cold transplant will reduce temperature sensitivity (Q10) for microbes from warmer soils, while the warm transplant would increase Q10 for microbes from colder soils (H3).To estimate microbial thermal traits, microbial growth (bacterial growth and fungal growth) and respiration were estimated at 10 different temperature conditions (0, 5, 10, 15, 20, 25, 30, 35, 40 and 45 °C). We found a significant cool-shift in microbial growth thermal traits after the cold transplant and warm-shifted thermal traits after the warm transplant. These changes led to a marked shift in thermal traits along the elevation gradient, indicating a strong legacy effect of ecosystem differences in temperature and a relatively minor influence of the 7-month transplant experiment. However, the warm transplant had a pronounced influence, driving the microbial growth traits of all samples closer to those of microbes with a warm-ecosystem origin. For respiration thermal traits, the transplant experiment did not alter thermal traits but did affect the respiration rate. The cold transplant reduced microbial respiration in soils with a history of warm temperatures, whereas the warm transplant increased respiration in soils with a history of colder temperatures. We did not find a significant effect of the transplants on bacterial growth and fungal growth rates, but total microbial growth rates tended to increase with MAT.  In support of the CQT hypothesis, we observed a decrease in Q10 for bacterial growth following the cold transplant in soils with a history of warmer temperature, and a strong increase in Q10 for both bacterial growth and respiration.

Selective pressures (i.e. resource limitation and competitive interaction) that drive the composition of ecological communities vary, and often operate on different ecological scales (ecological variables across varying spatial scales) than observed patterns. We studied the drivers of distribution and abundance of the American marten (Martes americana) and the carnivore community at three ecological scales on a Great Lakes island archipelago using camera traps. We found different drivers appeared important at each ecological scale and studying any of the three scales alone would give a biased understanding of the process driving the system. Island biogeography (resource limitation) was most important for carnivore richness, with higher richness on larger islands and lower richness as distance from the mainland increased. Marten presence on individual islands appeared to be driven by island size (resource limitation) and human avoidance (competitive interaction). Marten abundance at camera trap sites was driven by the cascading effect of coyotes (Canis latrans) on fishers (Pekania pennanti) (competitive interaction). Incorporating three ecological scales gave novel insights into the varying effects of resource limitation and competitive interaction processes. Our data suggests that ecological communities are structured through multiple competing ecological forces, and effective management and conservation relies on our ability to understand ecological forces operating at multiple ecological scales.

Heterotrophic microorganisms decompose soil organic matter to assimilate organic compounds that provide energy and carbon for growth and maintenance. The growth of microbial communities is thus at the heart of the carbon cycle, and understanding how microbial growth is controlled is arguably of paramount importance for understanding global carbon cycling in the present and future climate.  Most information on microbial growth comes from work with pure cultures (population level) or from studies of microbial community growth, while understanding the growth of individual microbial taxa in natural communities is poorly studied and understood. However, with the advent of new stable isotope probing techniques based on 18O from labelled water, it is now possible to look beyond the community level to the growth of individual populations of microorganisms in complex soil communities. In addition, recent advances in labelling growing microbial taxa without the addition of liquid water, the so-called ‘vapor qSIP', allow us to analyze microbial growth in complex communities without changing environmental conditions, a prerequisite for studying the behavior of microbial communities in climate change experiments. We report here on two climate change experiments in which we performed taxon-resolved growth measurements under different environmental conditions. Our results show the following: (1) Contrary to our expectations, changing environmental conditions (e.g., soil warming and drought) led to a change in the number of actively growing bacterial taxa, but not in their growth rates. Among other things, this challenges the paradigm developed from a plethora of measurements of microbial community growth that microbial physiology is accelerated by higher temperatures. (2) Many microbial taxa were only actively dividing in specific climate change treatments, i.e., under specific environmental conditions. We conclude that the realized ecological niche of bacteria appears to be much smaller than community growth measurements suggest. Testing, for example, the temperature niche of individual populations (with presumably different functional traits) may therefore lead to very different predictions of soil functions in a future climate. (3) Compared to estimates of total soil microbial community composition (e.g., amplicon sequencing of the 16S rRNA gene), the actively growing community is more sensitive to changes in environmental conditions, allowing a more accurate prediction of community structure in a future climate and its functional roles in biogeochemistry. Overall, measuring taxon-resolved population growth rates of complex communities provides a novel, more nuanced and sophisticated picture of soil ecosystems, which may help to develop better predictions of structural and functional changes in microbial ecosystems in a future climate.

A variety of biotic and abiotic variables have been shown to affect length of larval period and size of juveniles at metamorphosis in amphibians. However, influence of water quality on phenotypic plasticity of growth and development of tadpoles generally has received less attention. We examined how abiotic factors in the larval environment change over time and how these changes affect the growth and development of larval amphibians. Western Chorus Frogs, Pseudacris triseriata, in tallgrass prairie breed in ephemeral aquatic habitats including intermittent streams and bison wallows. Our objectives were to determine whether abiotic factors in the larval environment of P. triseriata changed predictably as pools dried and to determine whether these changes affected growth and development of tadpoles when the environment was simulated in the laboratory. In our field studies, pH increased gradually in wallows, whereas ammonium increased in streams, as each habitat dried. In the laboratory, we examined the effects of increased levels of pH and ammonium on growth and development of tadpoles collected from both wallows and streams. Tadpoles collected from streams metamorphosed significantly faster in the high ammonium treatment than tadpoles from wallows. In contrast, tadpoles from wallows metamorphosed faster in the high pH treatment than tadpoles collected from streams. Growth rates of tadpoles from streams were not significantly affected by high pH, whereas those from wallows were not significantly affected by high ammonium treatments. We suggest that changes in abiotic factors over the course of the larval period may influence developmental rate and that natal habitat may determine how tadpoles respond to changes in abiotic factors.

Here we investigated the effects of elevated temperature and low salinity on 2 important tidal foundation species, Fucus serratus and Fucus vesiculosus, to determine how these stressors interact. We conducted a 2-factorial experiment, exposing F. serratus and F. vesiculosus to 15 and 25°C combined with 5 and 25 PSU salinity over a period of 5 wk. The measured endpoints were survival, growth rate, chlorophyll a fluorescence (max. quantum yield and electron transport rate), photosynthetic performance, antioxidant capacity evaluated through superoxide dismutase enzyme activity, and oxidative damages assessed through lipid peroxidation products. Our results showed that exposure to high temperature and low salinity separately had negative effects on both species, but strongest for F. serratus. The combined effects of heat and low salinity were generally stronger than the isolated effects of each stressor, and were additive in most cases, suggesting that the effects of elevated temperature and low salinity can be predicted from single factor experiments. Our study provides valuable insights into the interaction effects of elevated temperature and reduced salinity on 2 important foundation species and highlights the vulnerability of these Fucus species to climate change-induced changes in abiotic factors.

AimIntraspecific trait variation is fundamental to understanding a species' adaptive capacity. Assessing phenotypic variation at different ecological scales is useful for evaluating species' vulnerability to changing environmental conditions. Here, we quantify the ecological scale of variation of phenotypic functional traits for a widespread dryland tree species and evaluate the strength of trait‐environment relationships across spatial gradients and in response to interannual variability in weather conditions.LocationWestern United States.TaxonConifer tree (Pinaceae): Pinus monophylla.MethodsNine reproductive and foliar morphological traits were measured from 23 sampling locations in nine mountain ranges, stratified across broad‐scale gradients of precipitation timing and quantity and local gradients of elevation. We partitioned trait variation within and among nested ecological scales (mountain range, site, tree, and tree growth year). We then used multivariate methods to quantify the association between environmental variables and ecological trade‐offs associated with both reproductive and foliar traits.ResultsMost variation was explained at the scale of individual trees (18%–46%) and between growth years (20%–30%), with smaller but variable contributions at the scale of sites (8%–25%) and mountain ranges (0%–15%). Trait values had low correlation with environmental variables (13%); however, 94% of the trait‐environment covariance was explained by two major axes of variation: (1) the drought‐stress gradient covarying with reproductive traits, and (2) precipitation patterns covarying with foliar morphology.Main conclusionsHigh levels of individual trait variation indicate within‐population adaptive capacity. Consistent relationships among range‐wide patterns of foliar and reproductive traits and broad‐scale climate gradients provide indirect evidence of local adaptation and may inform seed sourcing for restoration or the potential for assisted migration efforts. Quantification of intraspecific trait variation across multiple ecological scales is important for understanding the potential climate change response of dryland tree species.

Biogenic volatile organic compounds (BVOC) are a highly complex and highly diverse set of chemicals emitted into the atmosphere by the Earth's biosphere. They affect atmospheric composition of trace gases such as the mixing ratios of methane, carbon monoxide, and tropospheric ozone through their atmospheric oxidation. Atmospheric oxidation products also lead to formation of atmospheric aerosol, which plays a crucial role in defining Earth's radiative balance and impacts air quality.  Further increases in the average global temperature are expected for the following decades, with warmer and dryer conditions for Alpine regions. Warm winters appear to lead to earlier leaf-out. This may put trees at higher risk of late frost in spring. Thus, in addition to long-term changes in abiotic factors (temperature, water availability), the frequency of stress and double-stress events, such as a late spring frost and an extreme summer drought occurring in the same year, is expected to increase. How trees respond to such changes in abiotic factors and to abiotic (double) stress regarding their BVOC emissions composition and quantities is critical in understanding how atmospheric chemistry and SOA properties may be impacted.  During the summer of 2022, we studied the impact of elevated temperatures (heat), reduced water availability (drought), extreme events (early spring frost) and double stress (early spring frost followed by extreme summer drought) on tree seedlings i.) BVOC precursors in plant tissues (i.e., secondary metabolites) and ii.) BVOC gas-phase emissions. To this end, i.) we developed an analytical method for extraction and chromatographic separation of secondary metabolites from plant tissues, and ii.) we designed and built a novel plant chamber for BVOC gas-phase measurements online with a PTR-ToF-MS and offline with thermodesorption-GC-MS. We will present comprehensive results from experiments with Scots Pine, Beech, and Oak seedlings under various abiotic stress conditions. Our findings provide crucial insights for improving estimations of future BVOC emissions and their atmospheric impacts.

Towards a mechanistic understanding of soil nitrogen availability responses to summer vs. winter drought in a semiarid grassland

Stress levels over time in the introduced ascidian Styela plicata: the effects of temperature and salinity variations on hsp70 gene expression

We performed laboratory experiments to investi-gate whether the synthesis of the antioxidants α-tocopherol (vitamin E) and β-carotene in phytoplankton depends on changes in abiotic factors. Cultures of Nodularia spumigena, Phaeodactylum tricornutum, Skeletonema costatum, Dunaliella tertiolecta, Prorocentrum cordatum, and Rhodomonas salina were incubated at different tempe-ratures, photon flux densities and salinities for 48h. We found that abiotic stress, within natural ecological ranges, affects the synthesis of the two antioxidants in different ways in different species. In most cases antioxidant production was stimulated by increased abiotic stress. In P.tricornutumKAC 37 and D.tertiolectaSCCAP K-0591, both good producers of this compound, α-tocopherol accumulation was negatively affected by environmentally induced higher photosystem II efficiency (Fv /Fm ). On the other hand, β-carotene accumulation was positively affected by higher Fv /Fm in N.spumigena KAC 7, P.tricornutum KAC 37, D.tertiolecta SCCAP K-0591 and R.salina SCCAP K-0294. These different patterns in the synthesis of the two compounds may be explained by their different locations and functions in the cell. While α-tocopherol is heavily involved in the protection of prevention of lipid peroxidation in membranes, β-carotene performs immediate photo-oxidative protection in the antennae complex of photosystem II. Overall, our results suggest a high variability in the antioxidant pool of natural aquatic ecosystems, which can be subject to short-term temperature, photon flux density and salinity fluctuations. The antioxidant levels in natural phytoplankton communities depend on species composition, the physiological condition of the species, and their respective strategies to deal with reactive oxygen species. Since α-tocopherol and β-carotene, as well as many other nonenzymatic antioxidants, are exclusively produced by photo-synthetic organisms, and are required by higher trophic levels through dietary intake, regime shifts in the phytoplankton as a result of large-scale environmental changes, such as climate change, may have serious consequences for aquatic food webs.