Levels Of Environmental Stress Research Articles

New insights into assembly processes and driving factors of urban soil microbial community under environmental stress in Beijing

Rapid urbanization leads to drastic environmental changes, directly or indirectly affecting the structure and function of soil microbial communities. However, the ecological response of soil microbes to environmental stresses has not yet been fully explored. In this study, we used high-throughput sequencing to analyze the assembly mechanism and driving factors of soil microbial community under environmental stresses. The results indicated that environmental stresses significantly affected soil properties and the levels of beryllium, cobalt, antimony, and vanadium contamination in soil generally increased from the suburban areas toward the city core. The composition and distribution of soil microbial communities demonstrated clear differences under different levels of environmental stress, but there was no significant difference in microbial diversity. Random forest and partial least squares structural equation modeling results suggested that multiple factors influenced microbial diversity, but antimony was the key driver. The influence of environmental stress led to deterministic processes dominating microbial community assembly processes, which promoted the regional homogenization of soil microbes. Therefore, this study provides new insights into urban soil microbial management under environmental stresses.

Effects of Natural and Artificial Seawater Temporary Rearing on Flavor and Immunomodulation of Acanthopagrus schlegelii: A Study Based on GC-MS and UPLC-MS Untargeted Metabolomics

ABSTRACT Electronic tongue and metabolomic analysis (GC-MS and UPLC-MS techniques) were conducted to investigate the taste characteristics and metabolome of black sea bream before and after temporary rearing in natural seawater and artificial seawater, respectively. The natural seawater group showed reduced bitterness with advanced saltiness and sweetness, while the artificial seawater group had decreased umami. Metabolomic analysis revealed that most flavor-related metabolites and immune function-associated metabolites were downregulated, with a greater impact observed in the artificial seawater group. The artificial seawater group showed reduced immunity and disease resistance compared to the natural seawater group, indicating a greater level of environmental stress.

Assessment of Quality of Life of Parents of Children with Cerebral Palsy

Background: Cerebral palsy is a term used to describe a broad spectrum of motor disability which is non progressive and is caused by damage to the brain at or around birth. Care of a child with cerebral palsy is a source of tension and struggle for parents and causes many problems in meeting the child’s needs. Understanding the quality of life of this category of parents , will contribute entire and sufficient physiotherapeutic interventions by various techniques and examine what structural changes could be made to increase parent satisfaction. Study Design: This study is a cross sectional study approach to assess the quality of life of these parents in Pune. A sample of 30 parents of children of cerebral palsy age 3-17 years was selected through convenient sampling. Data were collected using WHO-QOL BREF, Parental stress index, Beck depression inventory questionnaire, focusing on quality of life, stress and depression of parents. Method: 30 Participants were selected based on the inclusion and exclusion criteria. Convenient sampling was done. Informed consent was obtained before data collection. Demographic details were recorded, and participants responded to the questionnaire, focusing on physical health, psychological health, social relationship and environmental barriers, stress and depression level. Descriptive statistics analyses were conducted to analyze the data. Results: The result showed as compare to father mother experienced lower quality of life, average depression level and increased stress level. This finding emphasizes the quality of life is severely affected suggesting the need to have family- centered approach for the management of children with cerebral palsy and evaluate unique challenges and experiences of parents to improve communication and support. Conclusion: This study concludes that the Quality of Life in Mothers is lower than that of Fathers of Cerebral Palsy child.

Associations between somatomotor-putamen resting state connectivity and obsessive-compulsive symptoms vary as a function of stress during early adolescence: Data from the ABCD study

Obsessive-compulsive symptoms (OCS) are relatively common during adolescence although most individuals do not meet diagnostic criteria for obsessive-compulsive disorder (OCD). Nonetheless, OCS during adolescence are associated with comorbid psychopathologies and behavioral problems. Heightened levels of environmental stress and greater functional connectivity between the somatomotor network and putamen have been previously associated with elevated OCS in OCD patients relative to healthy controls. However, the interaction of these factors within the same sample of individuals has been understudied. This study examined somatomotor-putamen resting state connectivity, stress, and their interaction on OCS in adolescents from 9–12 years of age. Participants (n = 6386) were drawn from the ABCD Study 4.0 release. Multilevel modeling was used to account for nesting in the data and to assess changes in OCS in this age range. Stress moderated the association between somatomotor-putamen connectivity and OCS (β = 0.35, S.E. = 0.13, p = 0.006). Participants who reported more stress than their average and had greater somatomotor-left putamen connectivity reported more OCS, whereas participants who reported less stress than their average and had greater somatomotor-left putamen connectivity reported less OCS. These data suggest that stress differentially affects the direction of association between somatomotor-putamen connectivity and OCS. Individual differences in the experience or perception of stress may contribute to more OCS in adolescents with greater somatomotor-putamen connectivity.

Impact of stress on the tear production of healthy cats.

This study aimed to determine the impact of acute stress on tear production in companion cats to provide a basis for minimizing stress-inducing stimuli during ophthalmic evaluations. A total of 24 healthy owned cats (12 males, 12 females) of mixed breed, aged 8 months to 7 years, with no history of ocular diseases, were selected for the study. The cats were housed in individual cages under controlled conditions for 6 days. The Schirmer tear test-1 (STT-1) was performed in the morning (between 9:00 am and 11:00 am) using test strips from the same batch. The first test (without stress) was conducted on the fifth day of acclimation, and the second test (with stress) on the sixth day. The stress stimulus consisted of recordings of barking dogs, cats fighting and the murmuring of people. For both tests, the heart rate was assessed with a stethoscope before, during and after the tests, and the environmental stress level was also evaluated. Results are presented as mean ± SD and 95% confidence interval (CI). The study found that STT-1 values were significantly higher (P = 0.009) with stress (22.2 ± 6.0 mm/min [95% CI 19.9-24.6]) than without stress (17.5 ± 6.9 mm/min [95% CI 14.8-20.2]). Similarly, the heart rate was significantly higher (P = 0.028) in stress vs non-stress conditions (213.4 ± 37.5 beats per minute [bpm] [95% CI 198.7-228.1] vs 171.5 ± 28.6 bpm [95% CI 160.3-182.7], respectively), and the environmental stress score was significantly higher (P <0.001) in stress vs non-stress conditions (3.3 ± 0.5 [95% CI 3.1-3.5] vs 1.2 ± 0.4 [95% CI 1.1-1.4], respectively). Stress increased tear production in cats. Although the mean STT-1 value obtained under stress conditions was within the normal range, stress can influence the test results. The use of cat friendly handling techniques facilitates execution of the STT-1.

Lifestyle Factors Counteract the Neurodevelopmental Impact of Genetic Risk for Accelerated Brain Aging in Adolescence

BackgroundThe transition from childhood to adolescence is characterized by enhanced neural plasticity and a consequent susceptibility to both beneficial and adverse aspects of one’s milieu. MethodsTo understand the implications of the interplay between protective and risk-enhancing factors, we analyzed longitudinal data from the Adolescent Brain Cognitive Development (ABCD) Study (n = 834; 394 female). We probed the maturational correlates of positive lifestyle variables (friendships, parental warmth, school engagement, physical exercise, healthy nutrition) and genetic vulnerability to neuropsychiatric disorders (major depressive disorder, Alzheimer’s disease, anxiety disorders, bipolar disorder, schizophrenia) and sought to further elucidate their implications for psychological well-being. ResultsGenetic risk factors and lifestyle buffers showed divergent relationships with later attentional and interpersonal problems. These effects were mediated by distinguishable functional neurodevelopmental deviations spanning the limbic, default mode, visual, and control systems. More specifically, greater genetic vulnerability was associated with alterations in the normative maturation of areas rich in dopamine (D2), glutamate, and serotonin receptors and of areas with stronger expression of astrocytic and microglial genes, a molecular signature implicated in the brain disorders discussed here. Greater availability of lifestyle buffers predicted deviations in the normative functional development of higher density GABAergic (gamma-aminobutyric acidergic) receptor regions. The two profiles of neurodevelopmental alterations showed complementary roles in protection against psychopathology, which varied with environmental stress levels. ConclusionsOur results underscore the importance of educational involvement and healthy nutrition in attenuating the neurodevelopmental sequelae of genetic risk factors. They also underscore the importance of characterizing early-life biomarkers associated with adult-onset pathologies.

The stress model of neuroticism and anxiety symptoms in fishermen.

Marine fishermen experience high levels of environmental and relationship stress and anxiety. The current study explored the role of stress in the relationship between neuroticism and anxiety symptoms among marine fishermen. Participants (fishermen from Tanmen in Qionghai city, Hainan Province) completed three questionnaires: the NEO-Five-Factor Inventory-Neuroticism Subscale (NEO-FFI-N); the Mental Stressor Investigation Questionnaire (MSIQ); and the Mood and Anxiety Symptoms Questionnaire-30-item-Anxious Arousal Subscale (MASQ-D30-AA) within 1 week before embarking on a fishing trip and then again within 1 week after their return to port. The data were subjected to correlational analyses and structural equation modelling. Positive correlations were found between NEO-FF-N (neuroticism) score, MSIQ score (total stress), MSIQ work-relationship score, ship environmental stress score, and MASQ score (anxiety symptoms). Regression analyses showed environmental stress had a significant moderating effect on the relationship between neuroticism and anxiety symptoms, and further analysis showed a mediating effect of work-relationship stress on the relationship between neuroticism and anxiety symptoms. Marine fishermen with high environmental stress had greater anxiety symptoms than those with low environmental stress. Neuroticism in marine fishermen further affects anxiety symptoms by affecting the level of work-relationship stress.

Combined effect of acute salt and nitrogen stress on the physiology of lichen symbiotic partners

Nitrogen pollution and excessive salinity are commonly regarded as one of the major environmental concerns in recent decades in many urban environments. Although in urban areas lichens are exposed to both salt and nitrogen stress, no studies have been conducted to date on the simultaneous impact and interaction of these factors on lichen physiology. The aim was to determine the effect of various combinations of NaCl and NH4NO3 doses on the physiology of epigeic lichen Cladonia rei. We also aimed to compare the response of lichens collected from polluted and unpolluted sites to verify whether lichens exposed to different levels of environmental stress in their native environment will react differently. The combined salt-nitrogen treatment caused significant disturbances in the integrity of cell membranes and chlorophyll fluorescence parameters. The most detrimental effect concerned the loss of cell membrane integrity, which suggests that this parameter can serve as a relevant indicator of acute salt-nitrogen stress incidents. Salt stress decreased the photosynthetic efficiency 1 h after exposure, but after 72 h, the FV/FM returned to the level characteristic of healthy lichens in experimental groups without and with small doses of ammonium nitrate. In contrast, recovery was not possible in combination with high nitrogen doses. This indicates that exposure to short-term salt stress in a nitrogen-poor environment only causes a temporary reduction in photosynthetic efficiency, but in urban eutrophic environments may have more serious consequences. The weakened physiological condition of the mycobiont manifested by an increased level of cell membrane damage and a persistent decrease in the photosynthetic efficiency of the photobiont in lichens growing along the roads may indicate an excess of nitrogen in the environment, enhanced by the effect of salt. Lichens collected from a heavy-metal-polluted habitat responded more strongly than those from an unpolluted habitat suggesting that in lichens previously affected by certain harmful factors, exposure to another stress factor may lead to greater disturbances. This is of particular importance for lichens inhabiting the vicinity of roads, since they are also under the influence of other pollutants emitted by road traffic.

Plasticity of the Anemonia viridis microbiota in response to different levels of combined anthropogenic and environmental stresses

Despite their recognized primary importance, marine coastal ecosystems around the globe are currently under threat, being subject to continuous local and global anthropogenic stressors. In this frame, understanding the response of coastal habitat-forming species to multiple stressors and their resilience is fundamental for the sustainable management of coastal ecosystems. In the present study, to provide some glimpses in this direction, we explored the response of theAnemonia viridis-associated microbiota to the combined anthropogenic stressors, which typically affect touristic hotspots at Mediterranean coastal sites. To this aim, two case studies have been carried out, the first in the Riccione coastal site (Italy, Center Mediterranean) and the second at Cap de Creus (Spain, North-western Mediterranean), where theA. viridismicrobiota was assessed under the conditions of both high and low anthropogenic pressure. According to our findings, theA. viridismicrobiota showed a relevant degree of plasticity in response to combined anthropogenic and environmental stressors, with changes that also mirrored variations in the surrounding seawater, thus indicating a close connection with the environment, from which potential symbiotic partners are selected. However, this potentially adaptive process also has a limitation, as observed in the highly anthropogenic impact site of Cap de Creus, whereA. viridis-associated microbiota appeared completely unstructured, as demonstrated by an increased dispersion according to the Anna Karenina principle. This raises the question about the resilience of theA. viridis-associated microbiota under combined climate and anthropogenic threats, as well as of the anthropogenic factors driving the observed dysbiosis changes.

Anthropogenic Pressure and Climate Change Could Severely Hamper the Avian Metacommunity of the Sicilian Wetlands

Our study shows that the current levels of anthropogenic exploitation of the Sicilian wetlands (Italy), combined with the likely exacerbation of climate-driven variables, are unsustainable and could soon exclude many bird species from this metacommunity. Sicily is the largest island in the Mediterranean Sea, and its wetlands represent a network of unreplaceable stopover sites that allow waterbirds to rest and refuel during migratory journeys along the central-eastern Mediterranean bird flyway. During the summer period, these species experience higher levels of environmental stress as water scarcity and anthropogenic pressure are at their peak. Through field surveys, geoprocessing and statistical analyses, we investigated: (a) the structure of the avian metacommunity of the largest Sicilian wetlands during July–September and (b) the effects of 10 (geographic, hydrological and anthropogenic) wetland attributes on avian diversity. We sampled 73 bird species, of which 30 are listed in annex I of the Birds Directive. The avian metacommunity was significantly nested and non-modular; in addition, it presented elevated beta diversity and random species assemblage. Environmental filtering superseded biotic interactions in determining species composition. Avian diversity was significantly favored by higher water levels, water-level fluctuations and water discharges, and disfavored by water diversion, salinity and tourism pressure. The knowledge concerning the particular structure of the avian metacommunity of the Sicilian wetlands can facilitate the implementation of conservation policies that could mitigate and compensate the effects of short- and mid-term risks.

Fluctuating asymmetry and oxidative stress indicate environmental stress of Cane toads Rhinella marina

Landfills led to biodiversity loss and have been identified as one of the major threats to wildlife, such as amphibians. There are useful tools that reflect environmental stress and help to monitor populations health before irreversible population decline occurs. Fluctuating asymmetry and oxidative stress have been used to analyze stress in wildlife. We analyzed the fluctuating asymmetry of morphological traits and the oxidative stress in the toad Rhinella marina that occur in contrasting habitats: a temperate forest and a landfill. We found higher levels of fluctuating asymmetry in toads of the landfill compared to individuals from the forest. Toads from the landfill also had higher levels of superoxide dismutase and total antioxidant capacity than toads from the forest, meanwhile lipid peroxidation was similar between toad's populations. Higher fluctuating asymmetry suggests higher environmental stress in toads from the landfill. We highlight that although cane toads have been described as an invasive species of anthropized environments, our findings confirm an increase in the levels of environmental stress in landfills.

Assessment of maize seed vigor under saline-alkali and drought stress based on low field nuclear magnetic resonance

To detect maize seed vigor under salt-alkaline and drought stress conditions, transverse relaxation time, physiological index, and electron microscopy images of germinating seeds were studied under different stress conditions. The results showed that the water in germinating maize seeds exist in bound water (T21), semi-bound water (T22), and free water (T23), in addition parabolic water (T24). The Pearson correlation analysis was performed with T2 relaxation parameters and seed vigor parameters, and this analysis yield nine optimized parameters. To predict vigor levels under different stress conditions, an error backpropagation artificial neural network model was developed, wherein the T2 chirality parameter was used as the input value, and the seed germination indices of different stress levels were used as the output values. The model could predict the environmental stress level of maize seed growth. The optimized parameter set showed a prediction accuracy of 92.50%, thus outperforming the T2 relaxation information model without parameter optimization (75.01%). The proposed method can collect data during the germination of maize seeds without any interference and achieve large-scale prediction of seed development status by small sample collection. With the stress environment was aggravated, the physiological structure of seed cells was changed, and the cell structure was destroyed and the ability of water absorption was disappeared. This analysis provides theoretical support and a reference basis for maize planting and production.

Effect of Seasons on Expressions of Milking Parlour Behaviours and Milk Yield of Crossbred Jersey Cows in Tropical Climate

Background: Milking behaviour of dairy cows has remarkable influences on their production efficacy. A number of genetic and environmental features controls and affects lactating behaviour of dairy cow. The aim of present study was to investigate the influence of seasons on milking behaviour and milk production of Jersey crossbred cows in tropical climate. Methods: The experiment was conducted on 94 Jersey crossbred cows maintained at organized dairy farm at ICAR-National Dairy Research Institute, Eastern Regional Station, Kalyani, West Bengal, India and there lactating behavioural features were studied during milking time inside the milking parlour under different seasons. The study period was divided into 3 season’s viz. rainy (September-October), winter (November-February) and summer (March-May). Result: Seasons showed influence upon milking behaviour and milk yield of cows. Temperament of cows were least (1.91±0.03) during winter seasons as compare to rainy and summer (2.15±0.03; 2.09±0.03) respectively and it differed significantly (P less than 0.01), simultaneously daily milk yield were also more (9.36±0.11) kgs during winter seasons as compare to rainy and summer (6.63±0.13; 8.58±0.13) respectively and it differed significantly (P less than 0.01). It can be concluded from the study that seasons showed significant influence on the milking behavioural features and milk yield in Jersey crossbred cows in tropical climate, which suggests that if dairy animals get favourable micro-climatic environment and reduced level of environmental stress they will behave more favourably and simultaneously their production efficacy also inclines.

Effects of sex and wet-bulb globe temperature on heart rate variability during prolonged moderate-intensity exercise: a secondary analysis.

Sex differences in heart rate (HR) and heart rate variability (HRV), a surrogate of cardiac autonomic modulation, are evident during rest and exercise in young healthy individuals. However, it remains unclear whether sex impacts HRV during prolonged exercise at differing levels of environmental heat stress. Therefore, we completed a secondary analysis upon the effects of sex and wet-bulb globe temperature (WBGT) on HR and HRV during prolonged exercise. To achieve this, HR and HRV were assessed in non-endurance-trained and non-heat-acclimatised healthy men (n=19) and women (n=15) aged 18-45 years during 180min of treadmill walking at a moderate metabolic rate (200W/m2: equivalent to ∼35% peak aerobic power) in 16, 24, 28, and 32°C WBGT. In the final 5min prior to exercise termination, HR was observed to be higher in women relative to men in all but the 32 °C WBGT. Although no sex differences were observed for the HRV metric of root-mean-square of successive differences, high-frequency power was higher in women relative to men across WBGT conditions. These findings indicate that, in healthy non-heat-acclimatised individuals, women respond to prolonged exercise-heat stress with a greater increase in HR despite cardiac vagal autonomic modulation remaining equal or increasing compared to men. Novelty: Prior to exercise termination, females respond with a greater increase in HR under all WBGTs except the hottest (32 °C). Sexinfluenced HRV metrics during all WBGTs, but results were mixed. Further characterisation of HRV sex differences remains an important area of research.

Association between racial/ethnic discrimination and pubertal development in early adolescence

Racial health disparities in the United States are a major concern, with Black or African Americans experiencing more morbidity and mortality at earlier ages compared to White Americans. More data is needed on the biological underpinnings of this phenomenon. One potential explanation for racial health disparities is that of accelerated aging, which is associated with increased stress exposure. Black Americans face disproportionate levels of environmental stress, specifically racial/ethnic discrimination. Here we investigated associations between self-reported experiences of discrimination and pubertal development (PD) in a diverse sample of young American adolescents (N = 11,235, mean age 10.9 years, 20.5% Black participants) from the Adolescent Brain Cognitive Development (ABCD) Study. Compared to their non-Black counterparts, Black youth experienced more racial/ethnic discrimination in the past year (10.4% vs 3.1%) and had a greater likelihood of being in late/post-pubertal status (3.6% vs 1.5% in boys, 21.3% vs 11.4% in girls). In both sexes, multivariable regression models run in the full sample revealed a cross-sectional association of experiences of racial/ethnic discrimination with pubertal development (boys: standardized beta [β]=0.123, P < .001; girls: β = 0.110, P < .001) covarying for demographics, BMI, and dietary habits. Associations remained significant when controlling for multiple other environmental confounders including other forms of (non-racial/ethnic) discrimination and other environmental adversities including poverty and negative life events, and when using parent-reported assessment of pubertal development. Furthermore, racial/ethnic discrimination was associated with elevated estradiol levels in girls (β = 0.057, P = .002). Findings suggest an association between experiences of discrimination and pubertal development that is independent of multiple environmental stressors. Future longitudinal studies are warranted to establish causal mechanism.

Validity of self-reported air pollution annoyance to assess long-term exposure to air pollutants in Belgium

In epidemiological studies, assessment of long term exposure to air pollution is often estimated using air pollution measurements at fixed monitoring stations, and interpolated to the residence of survey participants through Geographical Information Systems (GIS). However, obtaining georeferenced address data from national registries requires a long and cumbersome administrative procedure, since this kind of personal data is protected by privacy regulations. This paper aims to assess whether information collected in health interview surveys, including air pollution annoyance, could be used to build prediction models for assessing individual long term exposure to air pollution, removing the need for data on personal residence address.Analyses were carried out based on data from the Belgian Health Interview Survey (BHIS) 2013 linked to GIS-modelled air pollution exposure at the residence place of participants older than 15 years (n = 9347). First, univariate linear regressions were performed to assess the relationship between air pollution annoyance and modelled exposure to each air pollutant. Secondly, a multivariable linear regression was performed for each air pollutant based on a set of variables selected with elastic net cross-validation, including variables related to environmental annoyance, socio-economic and health status of participants. Finally, the performance of the models to classify individuals in three levels of exposure was assessed by means of a confusion matrix.Our results suggest a limited validity of self-reported air pollution annoyance as a direct proxy for air pollution exposure and a weak contribution of environmental annoyance variables in prediction models. Models using variables related to the socio-economic status, region, urban level and environmental annoyance allow to predict individual air pollution exposure with a percentage of error ranging from 8% to 18%. Although these models do not provide very accurate predictions in terms of absolute exposure to air pollution, they do allow to classify individuals in groups of relative exposure levels, ranking participants from low over medium to high air pollution exposure. This model represents a rapid assessment tool to identify groups within the BHIS participants undergoing the highest levels of environmental stress.

Reef Fish in the Mudflats of Kaledupa Island in Wakatobi National Park, Indonesia

Although frequently described as low-fertility or low-productivity habitat, coastal mudflats serve as important feeding grounds for fish. Many fish species from adjacent coral reefs, seagrass beds, or mangroves foraging periodically in mudflats. Because of this foraging behaviour, some local fishermen are known to utilize the mudflats to catch fish. However, the impact of this catching activities to the ecosystem has not been fully discovered. An examination of the fish community structure and levels of environmental stress had carried out in the mudflat ecosystem of the coast of Kaledupa Island in Wakatobi National Park (WNP), Indonesia. Two mudflat study sites were selected from the shore of Balasuna and Tampara villages located between mangroves and coral reefs. Data were sampled from the fish catch of local fishermen using fish fences (sero) installed in each mudflat area. Fish community structure was analyzed using diversity index and index of relative importance (IRI). ABC curves and species exploitation rate were used to assess the local environmental pressure. A total of 74 fish species were recorded from the mudflats of Kaledupa, which was found to be dominated by reef-associated fish species, comprising 63 species and accounting for 85% of the total catch. Additionally, although both sites had relatively high reef fish diversity, the obtained Clarke’s W-statistic values were approximately 0, indicating that the local fish communities presented moderate levels of disturbance. Three out of five fish species with the highest IRI values were found to be over-exploited, namely Siganus canaliculatus, Lethrinus ornatus, and Lethrinus variegatus.

Histopathology and Morphometric Characters of Tilapia guineensis as Biomarker to Evaluate Level of Environmental Stress in Badagry and Ojo Creeks, Lagos, Nigeria

Forty wild adult Tilapia guineensis were sourced from Ojo and Badagry creeks between January and March 2021, to investigate its morphometric character (total length, body weight, standard length, and head depth) and tissues structure (gill, muscle and small intestine) differences. Samples were collected and analysed using standard methods. The results showed no significant difference (P&lt;0.05) between the mean total length, body weight, standard length, and head depth of Tilapia guineensis recorded from both creeks. Length-weight relationships of T. guineensis obtained from both creeks showed negative allometry(b&lt;3) growth pattern while its condition factor (k) value was more significant than one, which indicated that the fishes are in good condition. Muscle of T.guineensis from Ojo creek showed a severe lesion of muscle bundle, degeneration of muscular bundle and shortening of bundles. Similarly, the gills structure of T. guineensis from Ojo creek showed severe degeneration, hyperplasia of secondary gill lamellae, and curling of secondary lamellae with unclear water channels. It is also characterized by hypertrophy of lamellae, and there is evidence of partial fusion of lamellae and dilation of gill filament. The observation of none lesion or degenerated tissues of T. guineensis in Badagry creek could suggest that Ojo creek is more subjected to effluents or other environmental stressors than Badagry creek. In conclusion, T. guineensis from Badagry creek is less affected by any environmental contaminants than T. guineensis from Ojo creek. Therefore, a collective effort towards ensuring reduction in direct discharge of untreated effluent or avoidance of another unhygienic usage of the creeks is very pertinent.

Environmental stress-discriminatory taxa are associated with high C and N cycling functional potentials in dryland grasslands

Increasing environmental stress strongly affects soil microbial communities, but the responses of the microbial assembly and the functional potential of the dominant microbial community in the presence of environmental stress in drylands are still poorly understood. Here, we undertook a broad appraisal of the abundance, diversity, similarity, community assembly, network properties and functions of soil microbiomes in 82 dryland grasslands along environmental gradients. We found that the bacterial and fungal diversity and community similarity showed different sensitivities to environmental stress (decreased mean annual precipitation (MAP) and soil nutrient levels and increased soil pH), and MAP was the most important factor influencing microbial community patterns. In addition, the dominant subcommunity of both bacteria and fungi was more sensitive to environmental stress than the nondominant subcommunity. Although increasing environmental stress decreased microbial phylogenetic clustering, it had no effects on the stochastic and deterministic assembly process balance. Moreover, we identified 101 bacterial and 34 fungal environmental stress-discriminatory taxa that were sensitive to environmental stress, and these bacterial markers showed a high correlation with the abundance of carbon (C) and nitrogen (N) cycling-related genes, whereas the taxa classified as connectors in the network were mainly correlated with C degradation genes. Our study shows that the different responses of bacteria and fungi to environmental stress bring challenges to predicting microbial function, but a relatively small number of taxa play an important role in driving C and N cycling-related functional genes, indicating that identifying an organism's phenotypic characteristics or traits of key taxa may improve our knowledge of the microbial response to ongoing global changes.

Stability of chironomid community structure during historic climatic and environmental change in subarctic Alaska

AbstractBy understanding lake ecosystem resilience in the face of increasing environmental and anthropogenic stress, we can hope to anticipate future ecosystem instability. We assess recent historic ecosystem resilience using composition and network analyses of empirical zoobenthos chironomid (Diptera: Chironomidae; nonbiting midges) reconstructions from three Subarctic Alaskan lakes, spanning the last c. 200 yr. We measured community richness, turnover and structure using taxon richness, beta diversity, and network skewness, respectively. Simulated taxonomic networks were created to establish the sensitivity of these metrics to changes in taxon connectivity, and to inform the interpretation of empirical chironomid records. The models indicated that beta diversity was more sensitive to taxon loss, while skewness was more sensitive to taxon gain. Both beta diversity and skewness were required to understand structural change under taxon replacement. The simulated arrival of strongly connected taxa caused a greater decrease in skewness than the arrival of weakly connected taxa. The empirical data sets indicated a rise in taxon richness (measured as rarefaction) and beta diversity in the recent samples. Changes in chironomid composition were associated with climate warming (replacement of cold taxa with temperate taxa) and increased lake biological productivity (the arrival of macrophyte‐associated taxa). Skewness was predominantly negative across the lakes, indicating high taxon connectivity and structural stress. However, little directional change in the skewness trends suggests some resilience within the chironomid community structures in relation to the current levels of climate and environmental stress. Continued climatic warming, and associated rises in nutrient levels, may cause further structural stress and ecological degradation.