Social anxiety disorder-associated gut microbiota increases social fear.

Social anxiety disorder (SAD) is a crippling psychiatric disorder characterized by intense fear or anxiety in social situations and their avoidance. However, the underlying biology of SAD is unclear and better treatments are needed. Recently, the gut microbiota has emerged as a key regulator of both brain and behaviour, especially those related to social function. Moreover, increasing data supports a role for immune function and oxytocin signalling in social responses. To investigate whether the gut microbiota plays a causal role in modulating behaviours relevant to SAD, we transplanted the microbiota from SAD patients, which was identified by 16S rRNA sequencing to be of a differential composition compared to healthy controls, to mice. Although the mice that received the SAD microbiota had normal behaviours across a battery of tests designed to assess depression and general anxiety-like behaviours, they had a specific heightened sensitivity to social fear, a model of SAD. This distinct heightened social fear response was coupled with changes in central and peripheral immune function and oxytocin expression in the bed nucleus of the stria terminalis. This work demonstrates an interkingdom basis for social fear responses and posits the microbiome as a potential therapeutic target for SAD.

A Pleistocene legacy structures variation in modern seagrass ecosystems.

Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.

Temperature dependence of competitive ability is cold-shifted compared to that of growth rate in marine phytoplankton.

The effect of climate warming on community composition is expected to be contingent on competitive outcomes, yet approaches to projecting ecological outcomes often rely on measures of density-independent performance across temperatures. Recent theory suggests that the temperature response of competitive ability differs in shape from that of population growth rate. Here, we test this hypothesis empirically and find thermal performance curves of competitive ability in aquatic microorganisms to be systematically left-shifted and flatter compared to those of exponential growth rate. The minimum resource requirement for growth, R*-an inverse indicator of competitive ability-changes with temperature following a U-shaped pattern in all four species tested, contrasting from their left-skewed density-independent growth rate thermal performance curves. Our results provide new evidence that exploitative competitive success is highest at temperatures that are sub-optimal for growth, suggesting performance estimates of density-independent variables might underpredict performance in cooler competitive environments.

Caesarean section and associated factors in Nigeria: assessing inequalities between rural and urban areas-insights from the Nigeria Demographic and Health Survey 2018.

INTRODUCTION: When medically indicated, caesarean section (CS) can be a life-saving intervention for mothers and their newborns. This study assesses the prevalence of CS and its associated factors, focussing on inequalities between rural and urban areas in Nigeria. METHODS: We disaggregated the Nigeria Demographic and Health Survey 2018 and performed analyses separately for Nigeria's overall, rural, and urban residences. We summarised data using frequency tabulations and identified factors associated with CS through multivariable logistic regression analysis. RESULTS: CS prevalence was 2.7% in Nigeria (overall), 5.2% in urban and 1.2% in rural areas. The North-West region had the lowest prevalence of 0.7%, 1.5% and 0.4% for the overall, urban and rural areas, respectively. Mothers with higher education demonstrated a greater CS prevalence of 14.0% overall, 15.3% in urban and 9.7% in rural residences. Frequent internet use increased CS prevalence nationally (14.3%) and in urban (15.1%) and rural (10.1%) residences. The southern regions showed higher CS prevalence, with the South-West leading overall (7.0%) and in rural areas (3.3%), and the South-South highest in urban areas (8.5%). Across all residences, rich wealth index, maternal age ≥ 35, lower birth order, and ≥ eight antenatal (ANC) contacts increased the odds of a CS. In rural Nigeria, husbands' education, spouses' joint healthcare decisions, birth size, and unplanned pregnancy increased CS odds. In urban Nigeria, multiple births, Christianity, frequent internet use, and ease of getting permission to visit healthcare facilities were associated with higher likelihood of CS. CONCLUSION: CS utilisation remains low in Nigeria and varies across rural-urban, regional, and socioeconomic divides. Targeted interventions are imperative for uneducated and socioeconomically disadvantaged mothers across all regions, as well as for mothers in urban areas who adhere to Islam, traditional, or 'other' religions. Comprehensive intervention measures should prioritise educational opportunities and resources, especially for rural areas, awareness campaigns on the benefits of medically indicated CS, and engagement with community and religious leaders to promote acceptance using culturally and religiously sensitive approaches. Other practical strategies include promoting optimal ANC contacts, expanding internet access and digital literacy, especially for rural women (e.g., through community Wi-Fi programs), improving healthcare infrastructure and accessibility in regions with low CS prevalence, particularly in the North-West, and implementing socioeconomic empowerment programs, especially for women in rural areas.

Connecting families: a qualitative study examining the experiences of parenting young children under financial strain in Ontario, Canada.

BACKGROUND: There is little research investigating the subjective experiences of parenting young children while living in poverty and experiencing financial strain using qualitative methodologies. Therefore, the objective of this study was to employ a qualitative approach to provide a nuanced and balanced view on the topic of parenting young children under financial strain in the Canadian context. METHODS: We conducted a qualitative study using semi-structured interviews between July and August 2021 in Kingston, Ontario, Canada. Sixteen participants aged 20-39 self-identified as living under financial strain while parenting a child aged 2-5 years. A qualitative inductive thematic analysis was undertaken with a focus on describing the contents of the data. RESULTS: Four major themes emerged from the data: experience of being a parent, impact of financial strain on the family unit, impact of financial strain on the children, and impact of financial strain on the parent. Numerous deleterious physical, mental, and material impacts on the family unit and parent were identified, however parent-perceived impacts of financial strain on their children were minimal. Parents described striking levels of resourcefulness and resiliency in providing the necessities for their families, absorbing the most significant impacts of financial strain through the phenomenon of self-sacrifice. CONCLUSION: The impacts of financial strain on families with young children are far reaching. Further research into the impacts of self-sacrifice on parents experiencing financial strain are needed to better understand this issue, and to inform social programming and resources that could help alleviate the deleterious impacts of poverty on parent mental, social, and physical health.

Aquatic biodiversity enhances multiple nutritional benefits to humans.

Humanity depends on biodiversity for health, well-being, and a stable environment. As biodiversity change accelerates, we are still discovering the full range of consequences for human health and well-being. Here, we test the hypothesis-derived from biodiversity-ecosystem functioning theory-that species richness and ecological functional diversity allow seafood diets to fulfill multiple nutritional requirements, a condition necessary for human health. We analyzed a newly synthesized dataset of 7,245 observations of nutrient and contaminant concentrations in 801 aquatic animal taxa and found that species with different ecological traits have distinct and complementary micronutrient profiles but little difference in protein content. The same complementarity mechanisms that generate positive biodiversity effects on ecosystem functioning in terrestrial ecosystems also operate in seafood assemblages, allowing more diverse diets to yield increased nutritional benefits independent of total biomass consumed. Notably, nutritional metrics that capture multiple micronutrients and fatty acids essential for human well-being depend more strongly on biodiversity than common ecological measures of function such as productivity, typically reported for grasslands and forests. Furthermore, we found that increasing species richness did not increase the amount of protein in seafood diets and also increased concentrations of toxic metal contaminants in the diet. Seafood-derived micronutrients and fatty acids are important for human health and are a pillar of global food and nutrition security. By drawing upon biodiversity-ecosystem functioning theory, we demonstrate that ecological concepts of biodiversity can deepen our understanding of nature's benefits to people and unite sustainability goals for biodiversity and human well-being.

ASSESSMENT OF ACUTE PHASE PROTEINS AND PROTEIN ELECTROPHORESIS IN HEALTHY GIBBONS (HYLOBATIDAE) IN MANAGED SETTINGS.

Acute phase proteins (APP) and protein electrophoresis (EPH) offer crucial insights into inflammation and overall health in various species. In this study, we validated serum amyloid A (SAA) and C-reactive protein (CRP) reagents for use with serum samples from gibbons (Hylobatidae, n = 50), spanning five species across four gibbon genera: eastern hoolock (Hoolock leuconedys), Javan (Hylobates moloch), pileated (Hylobates pileatus), siamang (Symphalangus syndactylus), and white-cheeked (Nomascus leucogenys). Preliminary reference intervals (n = 50) were calculated for SAA (1.8-48.1 mg/L), CRP (0.1-11.1 mg/L), and EPH via capillary zone electrophoresis, in healthy gibbons. Comparing clinically normal (n = 38) and abnormal (n = 12) individuals, significant differences were observed in the albumin/globulin ratio (P = 0.0003), prealbumin (P = 0.0345), and albumin (P = 0.0094), with abnormal individuals exhibiting statistically significantly higher γ-globulins (P = 0.0224), SAA (P = 0.0001), and CRP (P = 0.0003). Despite significant chromosomal rearrangements among different gibbon species, we found no statistically significant differences of SAA and CRP levels across species. However, some differences between species were observed in EPH fractions. This study presents the first report of the evaluation of APP and EPH in gibbons, underscoring the potential use of these biomarkers in gibbon health monitoring. Further research with larger sample sizes of both normal and abnormal gibbons is recommended to solidify the clinical utility of these biomarkers in these species.

FATAL ACUTE HEMOLYSIS FOLLOWING TRIAZOLE THERAPY IN AFRICAN PENGUINS (SPHENISCUS DEMERSUS).

Aspergillosis is a major cause of morbidity and mortality in penguins, with triazole antifungal drugs being commonly used for prophylaxis and treatment. This report describes 15 cases of fatal hemolysis associated with liquid itraconazole and voriconazole formulations administered to African penguins (Spheniscus demersus) from four institutions. All penguins underwent stressful events (e.g. relocation, induced molt) and were administered commercial liquid itraconazole formulations or compounded voriconazole liquid suspension. Observed clinical signs in affected penguins prior to death included hyporexia, weight loss, lethargy, dyspnea, red-tinged droppings, and obtunded mentation. Intra- and extravascular hemolysis and hemoglobinuric nephrosis were the primary pathologic manifestations on postmortem examination. The concentration-dependent hemolytic potentials of itraconazole, voriconazole, and commercial and compounded vehicle suspensions were evaluated in vitro by exposing chicken whole blood as a surrogate for penguin blood. Hemoglobin content in blood plasma was then measured by spectrophotometry. Neither itraconazole nor voriconazole alone induced hemolysis in vitro. The vehicle ingredients sorbitol and hydromellose induced hemolysis, but not at predicted plasma levels in chicken erythrocytes, suggesting neither the azole antifungals nor their major vehicles alone were likely to contribute to hemolysis in vivo in these penguins. Potential mechanisms of toxicosis include generation of an unmeasured reactive metabolite causing hemolysis, preexisting erythrocyte fragility, or species-specific differences in hemolytic thresholds that were not assessed in the chicken erythrocyte model. More research is needed on the potential for toxicosis of azole antifungal drugs and carrier molecules in this and other avian species.

The fitness value of ecological information in a variable world.

Information processing is increasingly recognized as a fundamental component of life in variable environments, including the evolved use of environmental cues, biomolecular networks, and social learning. Despite this, ecology lacks a quantitative framework for understanding how population, community, and ecosystem dynamics depend on information processing. Here, we review the rationale and evidence for 'fitness value of information' (FVOI), and synthesize theoretical work in ecology, information theory, and probability behind this general mathematical framework. The FVOI quantifies how species' per capita population growth rates can depend on the use of information in their environment. FVOI is a breakthrough approach to linking information processing and ecological and evolutionary outcomes in a changing environment, addressing longstanding questions about how information mediates the effects of environmental change and species interactions.

Effects of thermal fluctuations on biological processes: a meta-analysis of experiments manipulating thermal variability.

Thermal variability is a key driver of ecological processes, affecting organisms and populations across multiple temporal scales. Despite the ubiquity of variation, biologists lack a quantitative synthesis of the observed ecological consequences of thermal variability across a wide range of taxa, phenotypic traits and experimental designs. Here, we conduct a meta-analysis to investigate how properties of organisms, their experienced thermal regime and whether thermal variability is experienced in either the past (prior to an assay) or present (during the assay) affect performance relative to the performance of organisms experiencing constant thermal environments. Our results-which draw upon 1712 effect sizes from 75 studies-indicate that the effects of thermal variability are not unidirectional and become more negative as mean temperature and fluctuation range increase. Exposure to variation in the past decreases performance to a greater extent than variation experienced in the present and increases the costs to performance more than diminishing benefits across a broad set of empirical studies. Further, we identify life-history attributes that predictably modify the ecological response to variation. Our findings demonstrate that effects of thermal variability on performance are context-dependent, yet negative outcomes may be heightened in warmer, more variable climates.

Limited recovery following a massive seagrass decline in subarctic eastern Canada.

Over the last few decades, there has been an increasing recognition for seagrasses' contribution to the functioning of nearshore ecosystems and climate change mitigation. Nevertheless, seagrass ecosystems have been deteriorating globally at an accelerating rate during recent decades. In 2017, research into the condition of eelgrass (Zostera marina) along the eastern coast of James Bay, Canada, was initiated in response to reports of eelgrass decline by the Cree First Nations of Eeyou Istchee. As part of this research, we compiled and analyzed two decades of eelgrass cover data and three decades of eelgrass monitoring data (biomass and density) to detect changes and assess possible environmental drivers. We detected a major decline in eelgrass condition between 1995 and 1999, which encompassed the entire east coast of James Bay. Surveys conducted in 2019 and 2020 indicated limited changes post-decline, for example, low eelgrass cover (<25%), low aboveground biomass, smaller shoots than before 1995, and marginally low densities persisted at most sites. Overall, the synthesized datasets show a 40% loss of eelgrass meadows with >50% cover in eastern James Bay since 1995, representing the largest scale eelgrass decline documented in eastern Canada since the massive die-off event that occurred in the 1930s along the North Atlantic coast. Using biomass data collected since 1982, but geographically limited to the sector of the coast near the regulated La Grande River, generalized additive modeling revealed eelgrass meadows are affected by local sea surface temperature, early ice breakup, and higher summer freshwater discharge. Our results caution against assuming subarctic seagrass ecosystems have avoided recent global declines or will benefit from ongoing climate warming.

Gut Microbiome Composition and Its Association with Sleep in Major Psychiatric Disorders.

INTRODUCTION: Sleep disturbances are highly prevalent across most major psychiatric disorders. Alterations in the hypothalamic-pituitary-adrenal axis, neuroimmune mechanisms, and circadian rhythm disturbances partially explain this connection. The gut microbiome is also suspected to play a role in sleep regulation, and recent studies suggest that certain probiotics, prebiotics, synbiotics, and fecal microbiome transplantation can improve sleep quality. METHODS: We aimed to assess the relationship between gut-microbiota composition, psychiatric disorders, and sleep quality in this cross-sectional, cross-disorder study. We recruited 103 participants, 63 patients with psychiatric disorders (major depressive disorder [n = 31], bipolar disorder [n = 13], psychotic disorder [n = 19]) along with 40 healthy controls. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). The fecal microbiome was analyzed using 16S rRNA sequencing, and groups were compared based on alpha and beta diversity metrics, as well as differentially abundant species and genera. RESULTS: A transdiagnostic decrease in alpha diversity and differences in beta diversity indices were observed in psychiatric patients, compared to controls. Correlation analysis of diversity metrics and PSQI score showed no significance in the patient and control groups. However, three species, Ellagibacter isourolithinifaciens, Senegalimassilia faecalis, and uncultured Blautia sp., and two genera, Senegalimassilia and uncultured Muribaculaceae genus, were differentially abundant in psychiatric patients with good sleep quality (PSQI >8), compared to poor-sleep quality patients (PSQI ≤8). CONCLUSION: In conclusion, this study raises important questions about the interconnection of the gut microbiome and sleep disturbances.

Linking the influence and dependence of people on biodiversity across scales.

Biodiversity enhances many of nature's benefits to people, including the regulation of climate and the production of wood in forests, livestock forage in grasslands and fish in aquatic ecosystems. Yet people are now driving the sixth mass extinction event in Earth's history. Human dependence and influence on biodiversity have mainly been studied separately and at contrasting scales of space and time, but new multiscale knowledge is beginning to link these relationships. Biodiversity loss substantially diminishes several ecosystem services by altering ecosystem functioning and stability, especially at the large temporal and spatial scales that are most relevant for policy and conservation.

The International Initiative to Measure Perceived Risk in Arthroplasty: The Results From a Multinational Survey.

BACKGROUND: There is an inherent moral imperative to avoid complications from arthroplasty. Doing so at ideal cost is also associated with surgeon reputation, and, increasingly in health care delivery systems that measure and competitively score outcomes, reimbursement to the surgeons and their hospitals. As a result, patients who are perceived to be in higher risk comorbidity groups, such as the obese and diabetics, as well as those challenged by socioeconomic factors may face barriers to access elective arthroplasty. METHODS: In this initiative, surveys were sent to surgeons in 8 different countries, each adapted for their own unique payment, remuneration, and punitive models. The questions in the surveys pertained to surgeons' perception of risk regarding medical and socioeconomic factors in patients indicated for total hip or knee arthroplasty. This paper primarily reports on the results from Canada, Ireland, and the United Kingdom. RESULTS: The health care systems varied between a universal/state funded health care system (Canada) to those that were almost exclusively private (India). Some health care systems have "bundled" payment with retention of fees for postoperative complications requiring readmission/reoperation and including some with public publication of outcome data (United States and the United Kingdom), whereas others had none (Canada). There were some major discrepancies across different countries regarding the perceived risk of diabetic patients, who have variable Hemoglobin A1c cut-offs, if any used. However, overall the perception of risk for age, body mass index, age, sex, socioeconomic, and social situations remained surprisingly consistent throughout the health care systems. Any limitations set were primarily driven by surgeon decision making and not external demands. CONCLUSION: Surgeons will understandably try and optimize the health status of patients who have reversible risks as shown by best available evidence. The evidence is of variable quality, and, especially for irreversible social risk factors, limited due to concerns over cost and quality outcomes that can be influenced by experience-driven perceptions of risk. The results show that perceptions of risk do have such influence on access across many health care delivery environments. The authors recommend better risk-adjustment models for medical and socioeconomic risk factors with possible stratification/exclusions regarding reimbursement adjustments and reporting to help reverse disparities of access to arthroplasty.

An Empiricist's Guide to Using Ecological Theory.

AbstractA scientific understanding of the biological world arises when ideas about how nature works are formalized, tested, refined, and then tested again. Although the benefits of feedback between theoretical and empirical research are widely acknowledged by ecologists, this link is still not as strong as it could be in ecological research. This is in part because theory, particularly when expressed mathematically, can feel inaccessible to empiricists who may have little formal training in advanced math. To address this persistent barrier, we provide a general and accessible guide that covers the basic, step-by-step process of how to approach, understand, and use ecological theory in empirical work. We first give an overview of how and why mathematical theory is created, then outline four specific ways to use both mathematical and verbal theory to motivate empirical work, and finally present a practical tool kit for reading and understanding the mathematical aspects of ecological theory. We hope that empowering empiricists to embrace theory in their work will help move the field closer to a full integration of theoretical and empirical research.

The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans.

While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.

Seagrass (Zostera marina) transplant experiment reveals core microbiota and resistance to environmental change.

Zostera marina (seagrass) is a coastal marine angiosperm that sustains a diverse and productive ecosystem. Seagrass-associated microbiota support host health, yet the ecological processes that maintain biodiversity and stability of the seagrass leaf microbiota are poorly understood. We tested two hypotheses: (1) Microbes select seagrass leaves as habitat such that they consistently host distinct microbiota and/or core taxa in comparison to nearby substrates, and (2) seagrass leaf microbiota are stable once established and are resistant to change when transplanted to a novel environment. We reciprocally transplanted replicate seagrass shoots (natural and surface sterilized/dead tissue treatments) among four meadows with different environmental conditions and deployed artificial seagrass treatments in all four meadows. At the end of the 5-day experiment, the established microbiota on natural seagrass partially turned over to resemble microbial communities in the novel meadow, and all experimental treatments hosted distinct surface microbiota. We consistently found that natural and sterilized/dead seagrass hosted more methanol-utilizing bacteria compared to artificial seagrass and water, suggesting that seagrass core microbiota are shaped by taxa that metabolize seagrass exudates coupled with minor roles for host microbial defence and/or host-directed recruitment. We found evidence that the local environment strongly influenced the seagrass leaf microbiota in natural meadows and that transplant location explained more variation than experimental treatment. Transplanting resulted in high turnover and variability of the seagrass leaf microbiota, suggesting that it is flexibly assembled in a wide array of environmental conditions which may contribute to resilience of seagrass in future climate change scenarios.

The immune-kynurenine pathway in social anxiety disorder.

BACKGROUND: The tryptophan-kynurenine pathway is of major interest in psychiatry and is altered in patients with depression, schizophrenia and panic disorder. Stress and immune alterations can impact this system, through cortisol- and cytokine-induced activation. In addition, there is emerging evidence that the kynurenine pathway is associated with suicidality. There have been no studies to date exploring the immune-kynurenine system in social anxiety disorder (SAD), and indeed very limited human studies on the kynurenine pathway in any clinical anxiety disorder. METHODS: We investigated plasma levels of several kynurenine pathway markers, including kynurenine (KYN), tryptophan (TRYP) and kynurenic acid (KYNA), along with the KYN/TRYP and KYNA/KYN ratios, in a cohort of 32 patients with SAD and 36 healthy controls. We also investigated a broad array of both basal and lipopolysaccharide (LPS)-stimulated blood cytokine levels including IFN-γ, interleukin (IL)-10, IL-1ß, IL-2, IL-4, IL-6, IL-8 and tumor necrosis factor (TNF)-α. RESULTS: SAD patients had elevated plasma KYNA levels and an increased KYNA/KYN ratio compared to healthy controls. No differences in KYN, TRYP or the KYN/TRYP ratio were seen between the two groups. SAD patients with a history of past suicide attempt showed elevated plasma KYN levels and a higher KYN/TRYP ratio compared to patients without a history of suicide attempt. No differences were seen in basal or LPS-stimulated pro-inflammatory cytokine levels between the patients and controls. However, unstimulated IL-10, an anti-inflammatory cytokine, was significantly lower in the SAD group. A significant sex influence was evident with SAD males having lower levels of IL-10 compared to healthy males but no difference seen between SAD females and healthy females. CONCLUSIONS: The peripheral kynurenine pathway is altered in SAD and preferentially directed towards KYNA synthesis. Additionally, kynurenine pathway activation, as evidenced by elevated KYN and KYN/TRYP ratio, is evident in SAD patients with a history of past suicide attempt. While no differences in pro-inflammatory cytokines is apparent in SAD patients, lower anti-inflammatory IL-10 levels are seen in SAD males. Further investigation of the role of the immune-kynurenine pathway in SAD and other clinical anxiety disorders is warranted.

Trophic interactions modify the temperature dependence of community biomass and ecosystem function.

Aquatic ecosystems worldwide continue to experience unprecedented warming and ecological change. Warming increases metabolic rates of animals, plants, and microbes, accelerating their use of energy and materials, their population growth, and interaction rates. At a much larger biological scale, warming accelerates ecosystem-level processes, elevating fluxes of carbon and oxygen between biota and the atmosphere. Although these general effects of temperature at finer and broader biological scales are widely observed, they can lead to contradictory predictions for how warming affects the structure and function of ecological communities at the intermediate scale of biological organization. We experimentally tested the hypothesis that the presence of predators and their associated species interactions modify the temperature dependence of net ecosystem oxygen production and respiration. We tracked a series of independent freshwater ecosystems (370 L) over 9 weeks, and we found that at higher temperatures, cascading effects of predators on zooplankton prey and algae were stronger than at lower temperatures. When grazing was weak or absent, standing phytoplankton biomass declined by 85%-95% (<1-fold) over the temperature gradient (19-30 °C), and by 3-fold when grazers were present and lacked predators. These temperature-dependent species interactions and consequent community biomass shifts occurred without signs of species loss or community collapse, and only modestly affected the temperature dependence of net ecosystem oxygen fluxes. The exponential increases in net ecosystem oxygen production and consumption were relatively insensitive to differences in trophic interactions among ecosystems. Furthermore, monotonic declines in phytoplankton standing stock suggested no threshold effects of warming across systems. We conclude that local changes in community structure, including temperature-dependent trophic cascades, may be compatible with prevailing and predictable effects of temperature on ecosystem functions related to fundamental effects of temperature on metabolism.