Seasonal Temperature Changes Research Articles

Association of reproduction with seasonality in a subtropical viviparous fish, Jenynsia tucumana (Cyprinodontiformes: Anablepidae)

For fishes in temperate environments, the timing of seasonal reproduction has been correlated with changes in photoperiod and temperature. In tropical environments, seasonal hydrological patterns have been found to be drivers of the onset of reproduction. Despite these established relationships, data on reproductive seasonality for viviparous fish are limited. Here, we investigate aspects of reproduction in the viviparous fish Jenynsia tucumana Aguilera & Mirande, 2005 over the course of 12 months in the Salí River basin (Tucumán, Argentina), which is characterized by dry, short winters, and long, tropical summers. Size and reproductive data were collected each month. We found J. tucumana displayed marked sexual dimorphism in size, with females having higher length and weight when compared to males. Larger females have higher fecundities compared to smaller females. The breeding season corresponds with seasonal changes in photoperiod, air temperature, and rainfall, but ends with the arrival of heavy rainfall later in the season. Interestingly, J. tucumana produce and mature oocytes year-round, unlike congeneric species. This may be an adaptive strategy imposed by the irregular flooding of subtropical mountainous river stream habitats, which maintain high productivity well into early autumn.

Urban climate and cardiovascular health: Focused on seasonal variation of urban temperature, relative humidity, and PM2.5 air pollution

Seasonal effects on subclinical cardiovascular functions (CVFs) are an important emerging health issue for people living in urban environment. The objectives of this study were to demonstrate the effects of seasonal variations of temperature, relative humidity, and PM2.5 air pollution on CVFs. A total of 86 office workers in Taipei City were recruited, their arterial pressure waveform was recorded by cuff sphygmomanometer using an oscillometric blood pressure (BP) device for CVFs assessment. Results of paried t-test with Bonferroni correction showed significantly increased systolic and diastolic BP (SBP, DBP), central end-systolic and diastolic BP (cSBP, cDBP) and systemic vascular resistance, but decreased heart rate (HR), stroke volume (SV), cardio output (CO), and cardiac index in winter compared with other seasons. After controlling for related confounding factors, SBP, DBP, cSBP, cDBP, LV dp/dt max, and brachial-ankle pulse wave velocity (baPWV) were negatively associated with, and SV was positively associated with seasonal temperature changes. Seasonal changes of air pollution in terms of PM2.5 were significantly positively associated with DBP and cDBP, as well as negatively associated with HR and CO. Seasonal changes of relative humidity were significantly negatively associated with DBP, and cDBP, as well as positively associated with HR, CO, and baPWV. This study provides evidence of greater susceptibility to cardiovascular events in winter compared with other seasons, with ambient temperature, relative humidity, and PM2.5 as the major factors of seasonal variation of CVFs.

Regional climate change and possible causes over the Three Gorges Reservoir Area

The Three Gorges Project, the largest hydroelectric project in the world, has attracted widespread attention regarding its impact on regional climate. However, existing studies on the climate effects of the Three Gorges Project construction are not sufficient due to limited data accumulation. In this study, we analyzed the annual and seasonal trend changes in temperature, precipitation, and humidity over the Three Gorges Reservoir Area (TGRA) based on long-term meteorological stations data, remote sensing data, and reanalysis products. Observation minus reanalysis method (OMR) was used to reveal possible impacts of land cover changes on climate changes. Major results indicated that the TGRA experienced an overall warming trend for both annual and seasonal variations, with greater rising trends in the upstream. Except for autumn, the relative humidity of most regions mainly showed significant downward trends, indicating an overall drying trend in the TGRA. There was insignificant change in total precipitation and precipitable water vapor, with the largest variation observed during the summer. Although there were small differences among these datasets, their results of climate changes showed good consistency overall. In addition, the results of OMR indicated that land cover changes mainly had a warming and drying effect on the middle and upper reaches, and a cooling and moistening effect on the lower reaches of the TGRA. This may be due to the impact of land cover changes on the surface energy balance, thus affected temperature and humidity. The study has important reference value for understanding the climate changes in the TGRA and the climate effects brought about by large-scale engineering construction.

Water temperature and organic carbon control spatio‐temporal dynamics of particle‐attached and free‐living bacterial communities in a hypereutrophic urban river network

Abstract Bacteria are an important component of the aquatic ecosystem playing a key role in the transformation and mineralisation of allochthonous organic matter, nutrients and pollutants. However, there is no clear understanding of spatio‐temporal patterns of particle‐attached versus free‐living bacterial abundances, diversities and communities, which limits our in‐depth understanding of hypereutrophic urban river ecosystems and the mechanisms regulating nutrient cycling and biogeochemical transformations. In order to investigate spatio‐temporal patterns and associated factors for aquatic particle‐attached versus free‐living bacterial communities, we conducted a 2‐year study of four contrasting habitats in a hypereutrophic urban river network of eastern China. Bacterial abundance and community structure in relation to various environmental variables were assessed by epifluorescence microscopy and high‐throughput sequencing techniques. Results revealed that particle‐attached bacterial abundance depended mainly on suspended particle concentrations, whereas free‐living bacterial abundance was correlated with nutrient availability and water temperature. Organic carbon was related to a decrease of free‐living and particle‐attached bacterial richness, and particulate matter input increased free‐living bacterial diversity. Seasonal changes of water temperature were linked to the temporal dynamics of bacterial community composition, and the differences in total organic carbon concentrations contributed to spatial differences in bacterial community composition. There were significant differences in bacterial community composition between particle‐attached and free‐living assemblages in low‐turbidity/low‐nutrient rivers found in land areas comprising mainly natural vegetation. These differences were especially prominent for the relative abundances of Cyanobacteria and Actinobacteria, which were higher in the particle‐attached and free‐living fractions, respectively. However, no significant differences were found in turbid/nutrient‐rich rivers. Total organic carbon was the most significant factor shaping the composition similarity between particle‐attached and free‐living bacterial communities. Our findings indicate that spatio‐temporal variations in water temperature, suspended particle and resource availability, especially for organic carbon, appreciably contribute to changes in the abundance, diversity and composition of aquatic particle‐attached versus free‐living bacterial communities in the hypereutrophic urban river network. Considering that biodiversity is important for supporting ecosystem functioning, this study informs spatio‐temporal patterns of particle‐attached and free‐living bacterial abundance, diversity and composition of communities, and their underlying control mechanisms, thereby providing fundamental knowledge of microbial ecological functions for remediation and sustainable management of hypereutrophic urban river ecosystems.

Multi‐year time series reveals temporally synchronous diatom communities with annual frequency of recurrence in a temperate estuary

AbstractDiatoms are among the most abundant phytoplankton that inhabit coastal ecosystems, forming large blooms that fuel coastal food webs. Although diatoms are often large and morphologically distinct, many are small or morphologically cryptic making it difficult to understand the temporal dynamics of whole diatom communities and the environmental factors that drive them. Here, we investigated diatom diversity and its environmental correlates using 6 yr of monthly surface water samples from the Narragansett Bay Plankton Time Series to investigate the seasonal and annual variability of diatom species occurrence. High‐throughput amplicon sequencing of filtered biomass yielded 658 diatom amplicon sequence variants (ASVs), of which 347 were identified to species. Of the 49 diatom genera in the sequencing dataset, 33% had never been observed in the time series using microscopy (1959–2014). We observed a weak quadratic relationship between ASV richness and chlorophyll‐a concentrations, suggesting that richness decreases during blooms. There was a significant difference in diatom ASV richness by season and we identified distinct assemblages associated with different seasons. These assemblages were remarkably synchronous, exhibiting a sinewave‐like pattern, over 6 yr with an annual periodicity that correlated significantly with seasonal changes in temperature, light, and dissolved inorganic nitrogen. The annual cycle of diatom assemblages suggests stability in a key component of the estuarine food web known to influence ecosystem resilience and function. Deviations from the annual cycle of recurrence could be used to distinguish between changes in community structure driven by annual fluctuations in the environment and those driven by climate‐change stressors.

Strong seasonal patterns of DOC release by a temperate seaweed community: Implications for the coastal ocean carbon cycle.

Release of dissolved organic carbon (DOC) by seaweed underpins the microbial food web and is crucial for the coastal ocean carbon cycle. However, we know relatively little of seasonal DOC release patterns in temperate regions of the southern hemisphere. Strong seasonal changes in inorganic nitrogen availability, irradiance, and temperature regulate the growth of seaweeds on temperate reefs and influence DOC release. We seasonally surveyed and sampled seaweed at Coal Point, Tasmania, over 1 year. Dominant species with or without carbon dioxide (CO2 ) concentrating mechanisms (CCMs) were collected for laboratory experiments to determine seasonal rates of DOC release. During spring and summer, substantial DOC release (10.06-33.54 μmol C · g DW-1 · h-1 ) was observed for all species, between 3 and 27 times greater than during autumn and winter. Our results suggest that inorganic carbon (Ci ) uptake strategy does not regulate DOC release. Seasonal patterns of DOC release were likely a result of photosynthetic overflow during periods of high gross photosynthesis indicated by variations in tissue C:N ratios. For each season, we calculated a reef-scale net DOC release for seaweed at Coal Point of 7.84-12.9 g C · m-2 · d-1 in spring and summer, which was ~16 times greater than in autumn and winter (0.2-1.0 g C · m-2 · d-1 ). Phyllospora comosa, which dominated the biomass, contributed the most DOC to the coastal ocean, up to ~14 times more than Ecklonia radiata and the understory assemblage combined. Reef-scale DOC release was driven by seasonal changes in seaweed physiology rather than seaweed biomass.

Microeukaryotic predators shape the wastewater microbiome

The physicochemical parameters that shape the prokaryotic community composition in wastewater have been extensively studied. In contrast, it is poorly understood whether and how biotic interactions affect the prokaryotic community composition in wastewater. We used metatranscriptomics data from a bioreactor sampled weekly over 14 months to investigate the wastewater microbiome, including often neglected microeukaryotes. Our analysis revealed that while prokaryotes are unaffected by seasonal changes in water temperature, they are impacted by a seasonal, temperature-induced change in the microeukaryotic community. Our findings suggest that selective predation pressure exerted by microeukaryotes is a significant factor shaping the prokaryotic community in wastewater. This study underscores the importance of investigating the entire wastewater microbiome to develop a comprehensive understanding of wastewater treatment.

Temperature Calibration of Elevated Mg/Ca in Planktic Foraminifera Shells From the Hypersaline Gulf of Aqaba

AbstractThe Mg/Ca of marine calcareous Planktic Foraminifera (PF) shells is commonly used for sea surface temperature reconstructions. However, compared to open marine environments, hypersaline (>40) oligotrophic seas have been shown to accommodate PF with higher Mg/Ca and divergent temperature to Mg/Ca relationships. To investigate influencing factors of PF Mg uptake in hypersaline regions, we measured the Mg/Ca of two flux‐dominating PF species, Globigerinoides ruber albus and Turborotalita clarkei, derived from a monthly resolved time series of sediment traps in the Gulf of Aqaba, northern Red Sea as well as the corresponding temperature, salinity, and pH values. The PF exhibit elevated Mg/Ca which cannot be explained by post‐deposition or interstitial sediment diagenetic processes. G. ruber albus displays Mg/Ca trends that strongly follow seasonal mixed layer temperature changes. Conversely, T. clarkei Mg/Ca trends do not follow temperature but rather show significant Mg/Ca enrichment following mixing of the surface water column. We present a framework for incorporating elevated Mg/Ca into global Mg/Ca‐T calibrations for G. ruber albus and present a new Mg/Ca‐T calibration suitable for hypersaline marine environments.

Investigation of Taxonomic Relationship and Effect of Seasonal Temperature Changes Based on Protein Profiles of Fishes From Beyşehir, Suğla Lakes and Dam Apa

Besides traditional methods based on morphological characters, electrophoretic methods such as SDS-PAGE are preferred by taxonomists to make the right decision in the species identification process. In addition, the effect of environmental factors, such as pH, salinity, heat, and temperature on protein profiles are essential in various studies. In this study, we aimed to determine the degree of relationship in some fish species, such as Squalius lepidus, Cyprinus carpio, Carassius gibelio, Pseudophoxinus anatolicus, Tinca tinca, Alburnus orontis, Scardinius erythrophthalmus, Capoeta capoeta, Vimba vimba, Sander lucioperca living in Beyşehir, Suğla lakes and Apa Dam by SDS-PAGE method, and to examine seasonal differences by evaluating the effect of hot/cold water on protein profiles in fish. Although there were common major protein bands in all fish species studied, the presence of species-specific minor protein bands led to the separation of the species. The same fish species distributed in different lakes and dams were different both in minor bands, and changes in protein profiles were observed consequently on the same fish species synthesizing different proteins in different seasons. The data obtained from this study can contribute to systematic classification studies of fish.

PATHOGENETIC ASPECTS OF THE INFLUENCE OF SEASONALITY ON THE HEALTH OF PATIENTS WITH CHRONIC PATHOLOGY OF THE CARDIOVASCULAR SYSTEM: LITERATURE REVIEW

Purpose. To summarize and systematize the literature data on the pathogenetic aspects of the influence of seasonality on the health status of patients with chronic pathology of the cardiovascular system.
 Materials and methods. To analyze the literature, materials from the PubMed and PubMed Central resources of the US National Library of Medicine, Google Scholar, Elsevier Clinical Key and Elsevier Science Direct, as well as in the Russian RSCI database were used. The sample consisted of scientific papers devoted to the pathogenetic aspects of the influence of various meteorological factors on the course of cardiovascular pathology.
 Results. The generalized results of clinical and experimental studies presented in this review indicate both direct and indirect effects on the state of the cardiovascular system of seasonal changes in air temperature, atmospheric pressure, solar radiation, air humidity and geomagnetic indicators.
 Conclusion. Meteorological factors have a pronounced effect on the course of cardiovascular diseases both through direct mechanisms of influence, and through the inclusion in the pathogenesis of these diseases and the aggravation of existing risk factors. The pathogenetic mechanisms of the influence of weather factors on the state of the cardiovascular system are important for understanding the application points that can be influenced and improved by primary and secondary prevention of cardiovascular pathology.

Quantitative Mechanisms of the Responses of Abrupt Seasonal Temperature Changes and Warming Hiatuses in China to Their Influencing Factors

Abrupt temperature changes and warming hiatuses have a great impact on socioeconomic systems; however, their mechanisms remain unclear. In this study, the quantitative mechanisms of the responses of abrupt seasonal temperature changes and warming hiatuses in China to their influencing factors were analysed using the monthly mean temperature (Tav), mean minimum temperature (Tnav), and mean maximum temperature (Txav) from 622 meteorological stations in China covering 1951–2018, the CMIP6 model data, and data at large spatial scales, including Atlantic multidecadal oscillation (AMO) data. The results showed that the contributions of the influencing factors to the abrupt changes in Tav, Tnav, and Txav showed large spatial variability and peaked in the spring and summer and bottomed out in the autumn. The Pacific decadal oscillation (PDO) greatly impacted the abrupt temperature changes in Northeast China and North China at a contribution rate of approximately 12%, strongly influenced the abrupt temperature changes south of the Yangtze River, and markedly influenced the abrupt temperature changes in Northwest China. The AMO had a large impact on temperature in most regions of China in all seasons except for the summer. The MEI mainly affected the abrupt seasonal temperature changes in the region between 25° N and 35° N. The Arctic oscillation (AO) substantially impacted the warming hiatuses in Northeast China in the winter at a contribution rate of approximately 12%. These influencing factors contributed less to warming hiatuses than to abrupt temperature changes. Among the regional influencing factors, AP and WS greatly impacted warming hiatuses, more so than abrupt temperature changes, while relative humidity (RH) and solar radiation (SR) contributed little to warming hiatuses.

Noninteger Dimension of Seasonal Land Surface Temperature (LST)

During the few last years, climate change, including global warming, which is attributed to human activities, and its long-term adverse effects on the planet’s functions have been identified as the most challenging discussion topics and have provoked significant concern and effort to find possible solutions. Since the warmth arising from the Earth’s landscapes affects the world’s weather and climate patterns, we decided to study the changes in Land Surface Temperature (LST) patterns in different seasons through nonlinear methods. Here, we particularly wanted to estimate the noninteger dimension and fractal structure of the Land Surface Temperature. For this study, the LST data were obtained during the daytime by a Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. Depending on the time of the year data were collected, temperatures changed in different ranges. Since equatorial regions remain warm, and Antarctica and Greenland remain cold, and also because altitude affects temperature, we selected Riley County in the US state of Kansas, which does not belong to any of these location types, and we observed the seasonal changes in temperature in this county. According to our fractal analysis, the fractal dimension may provide a complexity index to characterize different LST datasets. The multifractal analysis confirmed that the LST data may define a self-organizing system that produces fractal patterns in the structure of data. Thus, the LST data may not only have a wide range of fractal dimensions, but also they are fractal. The results of the present study show that the Land Surface Temperature (LST) belongs to the class of fractal processes with a noninteger dimension. Moreover, self-organized behavior governing the structure of LST data may provide an underlying principle that might be a general outcome of human activities and may shape the Earth’s surface temperature. We explicitly acknowledge the important role of fractal geometry when analyzing and tracing settlement patterns and urbanization dynamics at various scales toward purposeful planning in the development of human settlement patterns.

Machine learning models for maintenance cost estimation in delivery trucks using diesel and natural gas fuels

The maintenance costs can represent about 15%–60% of the cost of produced goods depending on the type of goods transported. To comply with stringent emissions regulations, diesel engines are incorporated with complex after-treatment systems that demand increased maintenance. The availability of alternative fuels such as natural gas and propane has fostered the natural gas and propane powertrain systems as well as electrification options for heavy- and medium-duty vehicles. A critical barrier to adopting alternative fuel vehicles has been the lack of knowledge on comparative vehicle maintenance/repair costs with conventional diesel. Moreover, the region of operation, the type of vehicle operation, and seasonal temperature changes also affect the duty cycle which impacts the maintenance and repair costs. This study focuses on estimating the cost-per-mile for heavy-duty vehicles using machine learning models such as random forest, xgboost, neural networks, and a super-learner model. The super-learner model achieved an error as low as 0.0068 $/mile for mean absolute error and 0.0086 $/mile for root mean square error with a coefficient of determination/R-Squared of 97.28%. Specifically, the paper investigates the data collected from the maintenance and repair costs associated with delivery trucks using diesel and natural gas fuels. Since the availability of data is the major constraint, we leveraged the data collected by West Virginia University and the partnership with fleet companies. This allows for additional information related to maintenance costs and fleet-specific maintenance practices of alternative fuel vehicles. This study promotes clean fuel technologies and enables fleet management companies to adopt alternative fuel vehicles in case of similar or lower cost of maintenance compared to diesel vehicles resulting in reduced emissions and total cost of ownership.

Variation of blubber thickness of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) in human care: Adaptation to environmental temperature

Blubber thickness (BT) has a seasonal pattern in most small cetaceans in temperate and polar regions, which may be a crucial adaptive mechanism in response to environmental temperature changes. However, BT and environmental temperature correlations have never been tested experimentally in any cetacean species owing to logistical difficulties in the aquatic environment. The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis, YFP) is one of the smallest cetacean species worldwide, which exclusively inhabits the middle and lower regions of the Yangtze River in China. Here, we investigated BT variation patterns in YFPs and their relationship to environmental temperature changes using ultrasound imaging technology by longitudinally monitoring four YFPs in human care. We found that blubber was not evenly distributed in the skin of YFPs. BT increased along the craniocaudal axis from the head to the umbilical girth, and decreased towards the fluke, with relatively thicker blubber in the dorsal region than in the ventral and lateral regions. Significant negative correlations between BT and seasonal water temperature changes were observed in YFPs. However, different body regions display different sensitivities to seasonal temperature changes. The BT in the anal girth region exhibited noticeable seasonal changes. In contrast, the umbilical lateral and ventral regions showed relatively blunt seasonal changes, indicating different adaptive functions of the blubber in different regions. BT in the dorsal region decreased linearly with increasing water temperature. In the lateral and ventral regions, BT significantly changed with water temperature at a threshold of 18 ​°C. The YFPs had relatively thinner BT than similar-sized harbor porpoises that inhabit relatively high latitudes with much lower water temperatures. This further demonstrates the adaptive function of BT in response to environmental temperatures in small cetaceans. This study elucidates the seasonal pattern of BT variation in small cetaceans and provides insight into adaptation mechanisms of small cetaceans to temperature changes.

Cardiac remodeling caused by cold acclimation is reversible with rewarming in zebrafish (Danio rerio)

Cold acclimation of zebrafish causes changes to the structure and composition of the heart. However, little is known of the consequences of these changes on heart function or if these changes are reversible with rewarming back to the initial temperature. In the current study, zebrafish were acclimated from 27℃ to 20°C, then after 17 weeks, a subset of fish were rewarmed to 27°C and held at that temperature for 7 weeks. The length of this trial, 23 weeks, was chosen to mimic seasonal changes in temperature. Cardiac function was measured in each group at 27°C and 20°C using high frequency ultrasound. It was found that cold acclimation caused a decrease in ventricular cross-sectional area, compact myocardial thickness, and total muscle area. There was also a decrease in end-diastolic area with cold acclimation that reversed upon rewarming to control temperatures. Rewarming caused an increase in the thickness of the compact myocardium, total muscle area, and end-diastolic area back to control levels. This is the first experiment to demonstrate that cardiac remodeling, induced by cold acclimation, is reversible upon re-acclimation to control temperature (27°C). Finally, body condition measurements reveal that fish that had been cold-acclimated and then reacclimated to 27°C, were in poorer condition than the fish that remained at 20°C as well as the control fish at week 23. This suggests that the physiological responses to the multiple changes in temperature had a significant energetic cost to the animal. Summary statementThe decrease in cardiac muscle density, compact myocardium thickness and diastolic area in zebrafish caused by cold acclimation, was reversed with rewarming to control temperatures.

SEASONAL EFFECT ON BLOOD PRESSURE VARIABILITY IN HYPERTENSIVE PATIENTS ASSESSED BY DIFFERENT MEASUREMENT METHODS

Objective: The seasonal variation in temperature is well known to affect the level of blood pressure (BP). However, its impact on BP variability is uncertain. This study investigated the seasonal variation in BP variability in hypertensive patients assessed using office and out-of-office BP measurements. Design and method: Adult hypertensives on stable antihypertensive drug treatment were assessed with office (OBP), home (HBP), and ambulatory BP (ABP) measurements in winter, next summer, and in the next winter. BP variability was quantified using the standard deviation (SD) and coefficient of variation (CV). Results: Fifty-eight participants had complete data for winter and summer (mean age 65.2±7.9 [SD], 64% males, 21% obese, 48% smokers, 11% diabetes, 18% cardiovascular disease, 28% on a single antihypertensive drug, 38% on 2 drugs, 34% on > 2 drugs). OBP, HBP and daytime ABP were lower in summer than in winter (P<0.01), whereas nighttime ABP was unchanged (P = NS) (Figure). SD and CV for systolic OBP were higher in winter than summer (P<0.01/<0.05, respectively). BP variability assessed by HBP and ABP measurement did not differ in winter and summer (Figure). Forty participants had complete data for winter-summer-next winter. OBP, HBP and daytime ABP were higher in the second winter compared with summer excluding any order effect. Respective CV values showed no difference (p = NS). Conclusions: These preliminary data suggest that despite the considerable impact of seasonal changes in temperature on the levels of BP, its variability is not affected. Thus, variability appears to be an intrinsic feature of the individual's BP behaviour, which is largely unaffected by extrinsic seasonal factors.

Dynamic behaviors of water-saturated and frozen sandstone subjected to freeze-thaw cycles

In high-altitude cold areas, freeze-thaw (F-T) cycles induced by day-night and seasonal temperature changes cause numerous rock mass slope engineering disasters. To investigate the dynamic properties of rock in the natural environment of a high-altitude cold area, standard specimens were drilled from the slope of the Jiama copper mine in Tibet, and dynamic compression tests were performed on water-saturated and frozen sandstone with different numbers of F-T cycles (0, 10, 20, 30, and 40) by the split Hopkinson pressure bar (SHPB) system with a cryogenic control system. The influence of water-saturated and frozen conditions on the dynamic performance of sandstone was investigated. The following conclusions are drawn: (1) With increasing strain rate, the attenuation factor (λa) of water-saturated sandstone and the intensifying factor (λi) of frozen sandstone linearly increase. As the number of F-T cycles increases, the dependence factor (λd) of water-saturated sandstone linearly decreases, whereas the λd of frozen sandstone linearly increases. (2) The prediction equation of the dynamic compressive strength of water-saturated and frozen sandstone is obtained, which can be used to predict the dynamic compressive strength of sandstone after various F-T cycles based on the strain rate. (3) The mesoscopic mechanism of water-saturated and frozen sandstone's dynamic compressive strength evolution is investigated. The water softening effect causes the dynamic compressive strength of water-saturated sandstone to decrease, whereas the strengthening effect of pore ice causes it to increase. (4) The decrease in the relative dynamic compressive strength of water-saturated sandstone and the increase in the relative dynamic compressive strength of frozen sandstone can be attributed to the increased porosity.

Variation of Gene Expression in the Endemic Dinaric Karst Cave-Dwelling Bivalve Mollusk Congeria kusceri during the Summer Season

The cave systems of the Neretva River basin in the Dinaric Karst are home to Congeria kusceri, one of the very few known examples of stygobiotic bivalve mollusks, which displays several unique life history traits and adaptations that allowed its adaptation to the subterranean environment. This endemic species is undergoing rapid decline, most likely linked with habitat degradation, which might seriously threaten its survival in the next few decades. Unfortunately, the urgent need for effective conservation efforts is hampered by the lack of effective regulations aimed at preserving remnant populations as well as by our limited knowledge of the biology of this species. Although the precise factors underlying the disappearance of C. kusceri from its type locations are not entirely clear, the alteration of seasonal changes in water temperatures and alkalinity is most likely involved, as these are the main drivers of shell growth, spawning, and the onset and progression of the new gametogenic cycle. While these aspects have so far only been studied using morphological and physiological observations, future conservation efforts would certainly benefit from an integrated multidisciplinary approach. Here, using RNA-sequencing, we provide an overview of the modulation of gene expression recorded in five key tissues (the mantle, gonads, gills, adductor muscle, and digestive gland) between early June and late September. We highlight the presence of markedly tissue-specific responses, with the most dramatic changes affecting the gonads, mantle, and gills. We further identified a drastic switch in the use of energy budgets between the two periods, with evidence of ongoing shell growth and high metabolic activity in the mantle and gills at the early time point, followed by a massive redirection of all available energy to the gonads for the generation of new gamete primordia in early autumn.

Probing environmental and tectonic changes underneath Mexico City with the urban seismic field

Abstract. The sediments underneath Mexico City have unique mechanical properties that give rise to strong site effects. We investigated temporal changes in the seismic velocity at strong-motion and broadband seismic stations throughout Mexico City, including sites with different geologic characteristics ranging from city center locations situated on lacustrine clay to hillside locations on volcanic bedrock. We used autocorrelations of urban seismic noise, enhanced by waveform clustering, to extract subtle seismic velocity changes by coda wave interferometry. We observed and modeled seasonal, co- and post-seismic changes, as well as a long-term linear trend in seismic velocity. Seasonal variations can be explained by self-consistent models of thermoelastic and poroelastic changes in the subsurface shear wave velocity. Overall, sites on lacustrine clay-rich sediments appear to be more sensitive to seasonal surface temperature changes, whereas sites on alluvial and volcaniclastic sediments and on bedrock are sensitive to precipitation. The 2017 Mw 7.1 Puebla and 2020 Mw 7.4 Oaxaca earthquakes both caused a clear drop in seismic velocity, followed by a time-logarithmic recovery that may still be ongoing for the 2017 event at several sites or that may remain incomplete. The slope of the linear trend in seismic velocity is correlated with the downward vertical displacement of the ground measured by interferometric synthetic aperture radar, suggesting a causative relationship and supporting earlier studies on changes in the resonance frequency of sites in the Mexico City basin due to groundwater extraction. Our findings show how sensitively shallow seismic velocity and, in consequence, site effects react to environmental, tectonic and anthropogenic processes. They also demonstrate that urban strong-motion stations provide useful data for coda wave monitoring given sufficiently high-amplitude urban seismic noise.

Contrasting sensitivity of soil bacterial and fungal community composition to one year of water limitation in Scots pine mesocosms.

The soil microbiome is crucial for regulating biogeochemical processes and can thus strongly influence tree health, especially under stress conditions. However, little is known about the effect of prolonged water deficit on soil microbial communities during the development of saplings. We assessed the response of prokaryotic and fungal communities to different levels of experimental water limitation in mesocosms with Scots pine saplings. We combined analyses of physicochemical soil properties and tree growth with DNA metabarcoding of soil microbial communities throughout four seasons. Seasonal changes in soil temperature and soil water content and a decreasing soil pH strongly influenced the composition of microbial communities but not their total abundance. Contrasting levels of soil water contents gradually altered the soil microbial community structure over the four seasons. Results indicated that prokaryotic communities were less resistant to water limitation than fungal communities. Water limitation promoted the proliferation of desiccation-tolerant, oligotrophic taxa. Moreover, water limitation and an associated increase in soil C/N ratio induced a shift in the potential lifestyle of taxa from symbiotic to saprotrophic. Overall, water limitation appeared to alter soil microbial communities involved in nutrient cycling, pointing to potential consequences for forest health affected by prolonged episodes of drought.