Increase In Water Temperature Research Articles

Simulating synergistic impacts of climate change and human induced stressors on a northern Gulf of Mexico estuarine food web

Apalachicola Bay, an estuary located in northwest Florida, is likely to experience a continuing increase in the severity of the effects of changing climate and human-induced stressors, such as sea level rise and changes in freshwater inflow. A coupled hydrodynamic and food web modeling approach was used to simulate future scenarios of freshwater input and sea level rise in Apalachicola Bay from 2020 to 2049 to demonstrate the range of temporal and spatial changes in water temperature, salinity, fisheries species biomasses, total food web biomass and upper trophic level diversity. Additionally, a survey of Apalachicola Bay stakeholders was conducted concurrently with model development to assess stakeholder knowledge and concerns regarding species and environmental changes within the system. Results of the model simulations indicated an increase in water temperature across all scenarios and an increase or decrease in salinity with scenarios of low or high river flow, respectively. These results aligned with the impacts anticipated by stakeholders. White shrimp biomass increased with low river flow and decreased with high river flow, while Gulf flounder biomass decreased across all scenarios. The simulated trends in white shrimp biomass contrasted with stakeholder perceptions. The food web model results also showed an increase in total food web biomass and decrease in upper trophic level diversity across all future scenarios. For all modeled simulations, the largest differences in future environmental variables and species biomasses were between scenarios of low and high river flow, rather than low and high sea level rise, indicating a stronger influence of river flow on the abiotic and biotic characteristics of the estuary. Stakeholders anticipated a future reduction in river flow and increase in sea level rise as negatively impacting the Franklin County economy and stakeholders’ personal interaction with the Apalachicola Bay ecosystem. The use of the ensemble modeling approach combined with the stakeholder survey highlights the use of multiple knowledge types to better understand abiotic and biotic changes in the estuarine system. Results provide insight on the synergistic effects of climate change and human-induced stressors on both the estuarine food web and human community of Apalachicola Bay.

Flash evaporation method for improved desalination and cooling applications: An experimental study

The present study involves the experimental analysis of flash evaporation when sudden depressurization is created into a vertical cylindrical tube having a water volume range of 120 to 180 ml. During experiments, low water pool volumes are used to prevent the impact of gravity on the change of saturation temperature. The investigation is carried out by varying the initial water temperature and back pressure of the vacuum tank in the range of 65 to 80 ∘C and 11.32 to 41.32 kPa, respectively. It is observed that the evaporation rate and cooling rate are both enhanced by increasing the initial pool temperature and decreased by increasing the back pressure. It is reported that the evaporation rate is improved by 29.7 % with an increase in initial water temperature of 5 ∘C and decreases by 152 % with an increase in the back pressure of 10 kPa. It is also found that the cooling rate is improved by 21.6 % with an increase in initial water temperature of 5 ∘C and decreased by 59.2 % with an increase of water volume of 30 ml. It is clear from the visualization procedure that the degree of superheat plays a vital role in flash evaporation.

Spatial and Temporal Variability in Stream Thermal Regime Drivers for Three River Networks During the Summer Growing Season.

Many cold-water dependent aquatic organisms are experiencing habitat and population declines from increasing water temperatures. Identifying mechanisms which drive local and regional stream thermal regimes facilitates restoration at ecologically relevant scales. Stream temperatures vary spatially and temporally both within and among river basins. We developed a modeling process to identify statistical relationships between drivers of stream temperature and covariates representing landscape, climate, and management-related processes. The modeling process was tested in 3 study areas of the Pacific Northwest USA during the growing season (May [start], August [warmest], September [end]). Across all months and study systems, covariates with the highest relative importance represented the physical landscape (elevation [1st], catchment area [3rd], main channel slope [5th]) and climate covariates (mean monthly air temperature [2nd] and discharge [4th]). Two management covariates (ground water use [6th] and riparian shade [7th]) also had high relative importance. Across the growing season (for all basins) local reach slope had high relative importance in May, but transitioned to a regional main channel slope covariate in August and September. This modeling process identified regionally similar and locally unique relationships among drivers of stream temperature. High relative importance of management-related covariates suggested potential restoration actions for each system.

Using the electron transport system as an indicator of organismal thermal tolerance and respiratory exploitation

Freshwater ecosystems are undergoing rapid thermal shifts, making it increasingly important to understand species-specific responses to these changes. Traditional techniques for determining a species’ thermal tolerance are often lethal and time consuming. Using the enzyme activity associated with the electron transport system (ETS; hereafter referred to as enzyme assay) may provide a non-lethal, rapid, and efficient alternative to traditional techniques for some species. We used largemouth bass Micropterus salmoides (Lacepede, 1802) to test the efficacy of using an enzyme assay to determine thermal tolerance and respiratory exploitation in response to variable acclimation temperatures. Three tissue types were dissected from fish acclimated to 20, 25, or 30 °C and used in ETS assays at temperatures ranging from 7.5 to 40 °C. While there were significant differences among tissue types and acclimation temperatures, maximal enzyme activity occurred from 25.23 to 31.91 °C. Fish lost equilibrium at 39–42 °C in traditional CTmax trials, significantly higher than the upper optimum range determined via enzyme assays. The ratio of enzyme activity to measured whole organism respiration rate decreased with increasing water temperature, with the largest changes occurring at the upper optimum thermal range determined by enzyme assays. Our results indicate that ETS analysis may prove useful for obtaining biologically relevant thermal tolerances.

Synergistic effects between global warming and water quality change on modelled macrophyte species richness

Submerged freshwater macrophytes are crucial for the functioning of lakes. Their growth and survival follow environmental conditions like light, temperature, and nutrient availability. Hence, the impending increase in water temperature as well as changes of nutrients and turbidity will lead to changes in macrophyte geographic and depth distribution: Herein, we assess these potential changes. We apply an eco‐physiological macrophyte growth model to simulate biomass growth and survival of virtual species defined by random trait combinations within expert‐derived trait ranges for oligotraphentic, mesotraphentic, and eutraphentic species groups in deep lakes in Bavaria, Germany, which cover clear, moderate, and turbid lake conditions. The emergent potential species richness is compared with empirically observed species richness to evaluate general predictions for current conditions. Thereafter, we apply the model to scenarios of temperature increase and of turbidity and nutrient change to assess potential changes in species richness and the influence of species' traits on being an environmental change ‘winner' or ‘loser'. We find a cross‐lake, hump‐shaped pattern of potential species richness along depth. This largely reflects observed patterns, although mismatches were also detected and might be explained by missing processes and environmental heterogeneity within the lake. Rising temperature leads to increased richness of potential species in all lake types, species groups, and depths. Turbidity and nutrient change effects depend on depth and lake type. ‘Loser species' under increased turbidity and nutrient level are light consumptive and sensible to disturbances, while ‘winner species' have a high biomass production. These findings show that the hump‐shaped depth distributions of submerged macrophyte diversity can emerge solely considering eco‐physiology. The differential responses to environmental changes imply that management measures must account for lake type because those responses can have opposite trends depending on lake depth and type.

Modelling Heat Balance of a Large Lake in Central Tibetan Plateau Incorporating Satellite Observations

The thermodynamics of many lakes around the globe are shifting under a warming climate, affecting nutrients and oxygen transportation within the lake and altering lake biota. However, long-term variation in lake heat and water balance is not well known, particularly for regions like the Tibetan Plateau. This study investigates the long-term (1963–2019) variation in the heat balance of a large lake in the Tibetan Plateau (Nam Co) by combining the strengths of modeling and remote sensing. Remotely sensed lake surface water temperatures from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Along Track Scanning Radiometer Reprocessing for Climate: Lake Surface Water Temperature and Ice Cover (ARC-Lake) are used to calibrate and validate a conceptual model (air2water) and a thermodynamic model (LAKE) for the studied lake, for which in situ observation is limited. The results demonstrate that remotely sensed lake surface water temperature can serve as a valuable surrogate for in situ observations, facilitating effective calibration and validation of lake models. Compared with the MODIS-based lake surface water temperature (LSWT) for the period 2000–2019, the correlation coefficient and root mean square error (RMSE) of the LAKE model are 0.8 and 4.2 °C, respectively, while those of the air2water model are 0.9 and 2.66 °C, respectively. Based on modeling, we found that the water temperature of Nam Co increased significantly (p < 0.05) during the period of 1963–2019, corresponding to a warming climate. The rate of water temperature increase is highest at the surface layer (0.41 °C/10a). This warming trend is more noticeable in June and November. From 1963 to 2019, net radiation flux increased at a rate of 0.5 W/m2/10a. The increase in net radiation is primarily responsible for the warming of the lake water, while its impact on changes in lake evaporation is comparatively minor. The approaches developed in this study demonstrate the flexibility of incorporating remote sensing observations into modeling. The results on long-term changes in heat balance could be valuable for a systematic understanding of lake warming in response to a changing climate in the Tibetan Plateau.

The circumpolar impacts of climate change and anthropogenic stressors on Arctic cod (Boreogadus saida) and its ecosystem

Arctic cod (Boreogadus saida) is the most abundant forage fish in the Arctic Ocean. Here we review Arctic cod habitats, distribution, ecology, and physiology to assess how climate change and other anthropogenic stressors are affecting this key species. This review identifies vulnerabilities for different life stages across the entire distribution range of Arctic cod. We explore the impact of environmental (abiotic and biotic) and anthropogenic stressors on Arctic cod with a regional perspective in a scenario up to the year 2050 and identify knowledge gaps constraining predictions. Epipelagic eggs and larvae are more vulnerable to climate change and stressors than adults. Increased water temperatures, sea-ice decline, altered freshwater input, acidification, changing prey field, increased interspecific competition, new predators, and pollution are the principal stressors that will affect Arctic cod populations. Detrimental effects are likely to be greater in regions characterized by the advection of warmer Atlantic and Pacific waters. In contrast, Arctic cod may benefit from ocean warming in colder areas of the High Arctic. The risk from fisheries is moderate and primarily limited to bycatch. Overall, a decrease in suitable habitat and an associated decline in total Arctic cod biomass are predicted. In most Arctic seas, the relative abundance of Arctic cod within the fish community will likely fluctuate in accordance with cold and warm periods. A reduced abundance of Arctic cod will negatively affect the abundance, distribution, and physiological condition of certain predators, whereas some predators will successfully adapt to a more boreal diet. Regional management measures that recognize the critical role of Arctic cod are required to ensure that increased anthropogenic activities do not exacerbate the impacts of climate change on Arctic marine ecosystems. Ultimately, the mitigation of habitat loss for Arctic cod will only be achieved through a global reduction in carbon emissions.

Impact of ocean warming on a coral reef fish learning and memory.

Tropical ectotherms are highly sensitive to environmental warming, especially coral reef fishes, which are negatively impacted by an increase of a few degrees in ocean temperature. However, much of our understanding on the thermal sensitivity of reef fish is focused on a few traits (e.g., metabolism, reproduction) and we currently lack knowledge on warming effects on cognition, which may endanger decision-making and survival. Here, we investigated the effects of warming on learning and memory in a damselfish species, Acanthochromis polyacanthus. Fish were held at 28-28.5°C (control group), 30-30.5°C (moderate warming group) or 31.5-32°C (high warming group) for 2 weeks, and then trained to associate a blue tag (cue) to the presence of a conspecific (reward). Following 20 training trials (5 days), fish were tested for associative learning (on the following day) and memory storage (after a 5-days interval). The control group A. polyacanthus showed learning of the task and memory retention after five days, but increasing water temperature impaired learning and memory. A thorough understanding of the effects of heat stress, cognition, and fitness is urgently required because cognition may be a key factor determining animals' performance in the predicted scenario of climate changes. Knowing how different species respond to warming can lead to better predictions of future community dynamics, and because it is species specific, it could pinpoint vulnerable/resilience species.

Disturbance of oxidation/antioxidant status and histopathological damage in tsinling lenok trout under acute thermal stress.

The tsinling lenok trout (Brachymystax Lenok tsinlingensis) is a typical land-locked cold salmon. In this study, through the acute high temperature stress (16, 24, and 26°C), samples were taken at multiple temperature points to analyze the dynamic changes of serum non-specific immune indexes and histopathological changes of tissues of tsinling lenok trout. The histopathological investigation of different studied tissues revealed an increase of histological lesions' frequency and severity with increasing water temperature. The activity of T-SOD, GSH-Px, CAT, ACP, and LZM and MDA concentration are all impacted by high temperature stress. The activities of T-SOD, GSH-Px, and ACP are significantly lower in temperatures higher than 16°C (P<0.05). However, with the increase of water temperature, MDA content increased significantly. The activities of CAT and LZM were the highest at 24°C, which were significantly higher than those at 26°C (P<0.05). The above results indicate that 24°C is a "critical high temperature point" for tsinling lenok trout under heat stress, and this temperature point may be the critical point for tsinling lenok trout to enter "damaged" from adaptive adjustment. Our results can provide a theoretical basis for the development of genetic breeding, improvement, and control measures of heat stress in tsinling lenok trout in the future.

Quantitative relationships among high-throughput sequencing, cyanobacteria toxigenic genotype abundance and microcystin occurrence in bathing waters

Toxin-producing cyanobacteria pose significant threats to human and animal health if exposed during recreational activities in bathing waters. To better safeguard public health and reduce health risks during the bathing season, an effective monitoring and management strategy is required. Molecular tools used to monitor toxigenic cyanobacteria have been evaluated on the basis of the efficiency and applicability of the method used to (i) establish an early-warning monitoring strategy for EU bathing water sites using both targeted quantitative polymerase chain reaction (qPCR) and non-targeted high-throughput sequencing (HTS) genotype analysis and (ii) to compare the toxigenic potential of cyanobacteria with actual microcystin (MC) occurrence and concentrations. For this purpose, 16 bathing water sites were monitored according to the bathing water directive (BWD) of the European Union (EU) during the bathing season of the summer of 2020 in eastern Austria. The cyanobacterial community composition was analyzed through HTS and qPCR by targeting the microcystin synthetase B gene (mcyB), which indicates MC synthesis within the genera Microcystis and Planktothrix. Within the genus Microcystis, which was identified as the primary MC producer, the mcyB genotypes formed stable subpopulations that increased linearly in correlation with the total Microcystis population. Notably, the HTS cell equivalents assigned to Microcystis and Planktothrix correlated with the corresponding qPCR estimates of genotype abundance, which serves as a confirmation of the suitability of (semi)-quantitative sequencing through HTS. In addition to the elevated trophic state, reduced transparency, increasing water temperatures, as well as cyanobacterial HTS read numbers and Microcystis cell number equivalents per mL estimated through qPCR, were associated with positive MC samples. Therefore, in combination with the monitoring of standard environmental parameters, the use of HTS and qPCR techniques is considered highly useful to ensure the timely identification of health risks to recreational users, as mandated by the BWD.

Unveiling the rise of non-native fishes in eastern alpine mountain rivers: Population trends and implications.

Insufficient knowledge about the occurrence and spread of non-native fish in mountain regions has impeded effective management strategies worldwide. To address this gap, this study analysed over 1300 electrofishing surveys across 650 sites, encompassing a vast 7400 km2 area in the Eastern Alps. The primary objectives were to quantify the occurrence of non-native species and predict their spread in different river types. Furthermore, the study estimated population sizes and biomass trends for over 150 sites that were surveyed multiple times between 2000 and 2020. Out of the 42 fish species in the study region, 11 were identified as non-native. Notably, two invasive species of Union concern, Lepomis gibbosus and Pseudorasbora parva, increased their population sizes by 8% and 9% per year, over the past decades, supposedly supported by increasing water temperatures. Among the non-native species relevant for recreational fishing, Oncorhynchus mykiss populations showed a significant increase of approximately 7% per year, Salmo trutta populations remained stable, and Salvelinus fontinalis populations experienced a notable decline of approximately 7.4% per year. These varying population trends may be attributed to disparities in stocking intensities, with S. fontinalis receiving minimal stocking compared to the other species. This study revealed that non-native and invasive fish species are a relevant part of fish communities in mountain rivers. Non-salmonid non-natives thrive in warm rivers at lower elevations, whereas salmonid non-natives consolidate in steeper habitats. Because rising temperatures in mountain rivers will accelerate the spread and growth of these species, this first quantification of the current extent will improve fish management strategies in mountainous areas.

Increasing water temperature of the largest freshwater lake on the Mediterranean islands as an indicator of global warming

Global warming has been monitored for many years. The increase in air temperature and changes in the distribution and frequency of high temperatures are recorded continually. Lakes are one of the important water resources for aquatic ecosystems and water supply, which are significantly affected by global warming. The increase in lake water temperature increases the evaporation from the free lake surface, lowering the lake level, and changes the water quality. In the last few decades, analysis of changes in lake water temperature has been increasing. In situ measurements of water temperature in Vrana Lake on Cres island (Croatia), the largest freshwater lake on the Mediterranean islands, were analysed over 43 years. The results showed that the mean annual lake surface water temperature (LSWT) increased by 0.47 °C decade-1 (p < 0.0001). The increase in the mean annual lake summer surface water temperature (July–September) was 0.44 °C decade-1 (p < 0.0001), and the maximum annual LSWT was 0.56 °C decade-1 (p < 0.0001). All these amounts are in accordance with the published data on the increase in water temperature in the investigated European lakes. The number of days with LSWT higher than 25 °C increased by almost 9 d decade-1. An increase in the minimum LSWT (0.17 °C decade-1) corresponding to isothermal conditions was also determined but was not statistically significant. The minimum mean monthly LSWT increased by 0.36 °C decade-1 (p < 0.0001). Because the increase in water temperature can negatively affect the lake's ecosystem, and become a threat to safe water supply; LSWT, thermal stratification and evaporation should be continuously monitored. The impacts of climate warming on the lake stratification and aquatic ecosystems need to be further investigated.

The risk of bacterial virulence in the face of concentrated river pollution

Abstract The decrease in low-water flows and the increase in water temperature and other parameters as observed in the rivers over the last 50 years suggest that a concentration of compounds and pollutants is taking place, in connection with climate change and/or anthropisation (without discerning their respective contributions). These effects occur in a context where the rivers are already impacted by the presence of many pollutant cocktails (pesticides, drugs, and others). The authors now show that these pollutant cocktails – at the environmental concentrations currently found – constitute a threat to human health through their possible effects on the virulence of pathogenic bacteria. While certain genes of Salmonella Typhimurium may not experience an increased risk, the exposure to more concentrated cocktails (at a five-fold concentration) could potentially amplify certain virulent factors such as the motility of Pseudomonas aeruginosa H103. The findings indicate that pollution mixtures have an effect on the virulence potential of certain waterborne pathogenic bacteria, even at concentrations currently observed in rivers.

Acoustic telemetry reveals the drivers behind estuary–sea connectivity of an important estuarine-dependent fishery species, Pomadasys commersonnii, in the Breede Estuary, South Africa

The spotted grunter Pomadasys commersonnii is an important estuarine-dependent fishery species known to spawn along the east coast (KwaZulu-Natal Province) of South Africa. However, recent evidence suggests that this species also spawns along the southwest coast in the Western Cape Province (WC), which has necessitated the investigation of estuary–sea movements of adult P. commersonnii in the WC, and their link with spawning season and changing environmental conditions. Seasonal gonad maturation of adult P. commersonnii (n = 112) was investigated using histology and the gonadosomatic index. Seven adult P. commersonnii were acoustically tagged and monitored in the Breede Estuary (WC) between November 2016 and March 2020. Tagged individuals spent more time in the estuary (83.5%) than in the adjacent marine environment. Sea trips (n = 90) lasted on average 3.23 (SD 4.55) days (range 1–37 days), with most sea trips (82.6%) having a duration of less than 5 days. The majority of sea trips (>50%) occurred in austral summer, which coincided with the peak spawning season. Increases in estuary water temperatures in summer and river inflow in winter also influenced the presence of tagged fish in the sea. The high degree of residency of P. commersonnii in the Breede Estuary and short sea trips, along with increased frequency of reproductively ripe fish during summer months, supports the conclusion that regional spawning is occurring along the southwest coast. We suggest that management strategies should be put in place to protect the P. commersonnii population along the South African southwest coast, especially during summer, for the recovery of this population.

Performance and control of a reverse osmosis unit integrated with Pelton Wheel to supply emergency electric loads under various operating conditions

Nowadays, the whole world is moving very quickly into the field of seawater desalination. This is because the world suffers from a lack of potable water. Water and energy are adjoining linked fields. The present work aims at investigating the performance of a reverse osmosis (RO) plant integrated with Pelton Wheel under various operating conditions. The main reason for using Pelton turbine instead of the pressure exchanger (PX) is the low cost of Pelton compared to that of PX. The RO system integrated with the Pelton Wheel was tested under various operating pressures of 650, 700, 750, 800, and 850 kPa. Changing the feed water pressure affects the pressure of the reject entering the Pelton wheel and this, in turn, affects the velocity of the water jet. Also, the impact of varying the feed water salinity (total dissolved solids (TDS) = 400, 500, 600, 700, and 850 ppm) and temperature (20–39 °C) on the permeate and reject of RO was tested. In addition, a theoretical modeling was built to predict the performance of the RO system. The permeate flow rate was increased by raising the RO operating pressures. The permeate flow rate was augmented from 2.5 to 4.3 L min−1 when increasing the operating pressure from 650 to 850 kPa, respectively. Therefore, the permeate flow rate is enhanced by around 72% when increasing the operating pressure by only 30%. Besides, increasing the pressure by 30% (from 650 to 860 kPa) decreased the generated power of the Pelton Wheel by approximately 72% (from 960 to 270 W, respectively). Also, increasing the feed water salinity leads to raise the salinity of RO permeate, and vice versa. The RO permeate salinity is raised from 165 to 285 ppm when increasing the operating pressure from 650 to 850 kPa, respectively. As well, the more the increase in feed water temperature, the more improve in the permeate flux and salinity. The permeate TDS was decreased from 140 ppm at feed-water temperature 20 °C to 56 ppm at feed water temperature 39 °C. In this study, the Arduino program circuit was used to supply the required emergency loads by controlling the pressure values of high-pressure pump due to easy and open code program. Finally, the theoretical modelling results are in good correspondence with the experimental results. The average deviation among the theoretical and experimental results was 3.5%.

Dissolved Organic Matter Fractions and Their Removal in Full-Scale Drinking Water Treatment Process

Objectives:The objective of this study is to investigate characteristics about removal of dissolved organic matter (DOM) and its fraction for improving operation efficiency in an advanced water treatment plant. Methods:The monitoring of water quality was conducted at five processes such as raw water, pre-oxidation, after sedimentation, post-ozonation, after biological activated carbon (BAC) from July 2020 to August 2021 in advanced water treatment process (AWTP) supplying 180,000m&lt;sup&gt;3&lt;/sup&gt;/day. The concentration of DOC (dissolved organic carbon) and number of algae were monitored and LC-OCD was used to fractionate DOC to four species, biopolymer (BP), humic substance (HS), building blocks (BB), and low molecular weights (LMWs). Results and Discussion:The characteristics of raw water showed that the concentration of DOC and the number of algae increased with an increase in water temperature. The portion of BP and HS significantly increased at low and high water temperature, respectively, while BB and LMWs maintained the similar portion. The removal efficiency of DOC in the AWTP was achieved at 59% with each species of BP, HS, BB, and LMWs obtaining removal efficiency of 87%, 65%, 26%, and 52%, respectively. Coagulation/sedimentation/filtration showed removal efficiency of 84%, 56%, 20%, and 18% for BP, HS, BB, and LMWs, respectively, corresponding to their molecular weight. The effect of post-ozonation would be negligible except for BP. In BAC, removal efficiency of 49% and 12% were obtained for LMWs and BB (low molecular weight, respectively. As a result, the BP portion significantly decreased due to high removal efficiency, while BB portion was increased in the final treated water compared to raw water. Conclusion:Most of DOM was removed in coagulation/sedimentation/filtration and BAC, whereas oxidation process such as pre-chlorination, pre-ozonation and post-oxidation did not have an effect on DOM removal. In coagulation/sedimentation/filtration, 84% and 54% of the BP and HS were removed, while BAC removed 49% and 12% of LMWs and BB, respectively. It has been recommended to improve the removal efficiency of BB, which obtained the lowest removal efficiency in AWTP, and to enhance the removal efficiency of LMWs in BAC to inhibit microbial regrowth in the distribution system.

Water temperature and the growth of Ameletus inopinatus (Ephemeroptera: Ameletidae) in the Cairngorms, Scotland

Ameletus inopinatus Eaton, 1887 is the only arctic-alpine mayfly species found in the British Isles. Previous research in Europe using climate models has shown that the geographical range of this species is likely to contract as water temperatures increase. As such, A.inopinatus is particularly vulnerable to the impacts of climate warming. The impact of water temperature on the development of A.inopinatus larvae was investigated in the Cairngorms National Park in Scotland. We closely linked larval development to water temperature with snow cover playing an important role in ensuring emergence occurs before watercourses cease to flow in early summer. The results of this study confirm the vulnerability of A. inopinatus to rising water temperatures and provide new information to help target mitigation measures to prevent further losses of this species.

Nb2O5 passivation of WO3 thin films to prevent electrochromic performance degradation in heated water

Electrochromic thin films must be highly stable against heat and moisture for their application to devices operating in air atmosphere. In this study, we discuss the degradation of the surface morphology of sputtered WO3 thin films in heated water. When the water temperature and soaking times increase, the flat surface of film undergoes a pronounced transition and becomes rough causing partial etching off the film. Although the surface area available for ion intercalation increases by etching, the electrochromic performance of films degrades. We propose stacking a passivation layer of Nb2O5 to prevent the etching off the WO3 thin films and changes in their surface morphology. The surface morphology of the bilayer thin films soaked in water at 70 °C for 30 and 180 s does not change noticeably when the thicknesses of the Nb2O5 layers are 25 and 100 nm, respectively. Both the thin films exhibit transmittance modulations and coloration efficiencies comparable to those of the WO3 thin film without etching, suggesting effective passivation. Moreover, the stacks are stable during cyclic tests up to 700 cycles in an H2SO4 solution. In contrast, the soaked WO3 thin films lose their electrochromic switching capability after the 35th cycle. In conclusion, Nb2O5 passivation of WO3 thin films can effectively prevent their degradation under hot and moist conditions.

Effects of climate change-induced water temperature changes on the distribution of tidal river fish fauna in the Japanese archipelago

Intense anthropogenic impacts in tidal rivers can cause habitat loss and ecosystem degradation. In addition, changes in water temperature associated with climate change are significantly impacting the distribution area of fish fauna within tidal rivers. In the present study, we used long-term fish fauna data to determine the relationship between climate change-induced increases in water temperature and changes in the distribution of fish species in tidal rivers in the Japanese archipelago. The distribution ranges of many subtropical and tropical fish species were found to move northward in areas affected by warm currents, suggesting further possible distributional dispersal in future. This study is the first to examine the nationwide distributional changes and future projections of fish fauna in tidal rivers. The results suggest that many subtropical and tropical fishes are expanding their distribution areas in tidal rivers and in coastal and estuarine areas.

Reproductive behavior of Atlantic halibut (Hippoglossus hippoglossus) interpreted from electronic tags.

Reproductive timing, location, and behavior are important characteristics that determine marine population dynamics, structure, and resilience to threats, including fishing and climate change. It is challenging to evaluate factors driving variability in these reproductive traits in wild fishes because of the difficulty observing individuals in their natural environments. In the present study, we used high-resolution depth, temperature, and acceleration time series recorded by pop-up satellite archival tags to (1) identify and characterize patterns in depth and acceleration that may be indicative of spawning events in large Atlantic halibut (Hippoglossus hippoglossus), and (2) estimate the effects of individual traits (body size and sex) and environmental factors (location and temperature) on spawning time and frequency. Unique rapid rises observed in the winter depth profiles were interpreted as spawning events. The initiation of the first presumed spawning rise was negatively correlated to water temperature experienced during the prespawning season, suggesting that currently increasing water temperature in the Gulf of St. Lawrence may induce phenological change in halibut spawning time. The number of rises of batch-spawning females was unrelated to female body size. The present study demonstrates how electronic tagging can be used for in-depth characterization of timing, location, and behaviors associated with spawning in a large flatfish species. Such information can inform spatiotemporal management and conservation measures aiming to protect species from directed fishing and by-catch during spawning.