Infection dynamics of Shewanella spp. in Nile tilapia under varied water temperatures: A hematological, biochemical, antioxidant-immune analysis, and histopathological alterations.

In aquaculture, fluctuating water temperatures can act as a potent stressor, influencing the virulence and transmission dynamics of pathogenic bacteria, potentially triggering outbreaks and impacting fish health. The purpose of this work was to examine the impact of Shewanella spp. infection on hematological, biochemical, and antioxidant-immune parameters of Nile tilapia (Oreochromis niloticus) under different water temperatures. For this purpose, 180 fish were divided into 6 groups in triplicate (30 fish per group; 10 fish per replicate). Group 1 (G1), G2, and G3 were reared at varying water temperatures (22 °C, 28 °C, and 31 °C, respectively) without infection. While G4, G5, and G6 were IP-injected with 0.2 mL of Shewanella spp. (0.14 × 105) and reared at 22 °C, 28 °C, and 31 °C, respectively. Shewanella spp. infection induced significant lowering (p < 0.05) in hematological parameters (red and white blood cells, hemoglobin, and packed cell volume%) and immune-antioxidant responses (phagocytic activity%, phagocytic index, lysozyme, nitric oxide), total antioxidant capacity, catalase, and reduced glutathione, especially at 22 °C. Moreover, a significant increase (p < 0.05) in the hepato-renal function indicators (alanine aminotransferase, aspartate aminotransferase, urea, and creatinine), stress biomarkers (glucose and cortisol), malondialdehyde, and pro-inflammatory cytokines (interleukin-1ß and tumor necrosis factor-α) were the consequences of the Shewanella spp. infection, especially at 22 °C. The Shewanella spp. infection exhibited marked histopathological changes in the hepatic and renal tissues. Worthily, Shewanella spp. can cause detrimental alterations in Nile tilapia's hematological, biochemical, and antioxidant-immune parameters at various water temperatures, but the major detrimental changes were observed at a water temperature of 22 °C. Consequently, we can conclude that the infection dynamics of Shewanella spp. are exaggerated at 22 °C. These outcomes could help in understanding the nature of such an infection in Nile tilapia.

Water temperature and energy balance of floating photovoltaic construction water area-field study and modelling.

Floating photovoltaics (FPV) are an emerging renewable energy technology. Although they have received extensive attention in recent years, understanding of their environmental impacts is limited. To address this knowledge gap, we measured water temperature and meteorological parameters for six months under FPV arrays and in the control open water site and constructed a numerical model reflecting the water energy balance. Our results showed that FPV arrays caused diurnal variation in water temperature and microclimate. Specifically, we found that FPV had a cooling effect on their host waterbody during the daytime and a heat preservation effect at night, reducing diurnal variation. The diel oscillation of water temperature below FPV panels lagged behind that of open waters by approximately two hours. The microclimate conditions below FPV panels also changed, with wind speed decreasing by 70%, air temperature increasing during the daytime (averaging +2.01°C) and decreasing at night (averaging -1.27°C). Notably, the trend in relative humidity was the opposite (-3.72%, +14.43%). Correlation analysis showed that the degree of water temperature affected by FPV was related to local climate conditions. The numerical model could capture the energy balance characteristics with a correlation coefficient of 0.80 between the simulated and actual data. The shortwave radiation and latent heat flux below FPV panels was significantly reduced, and the longwave radiation emitted by FPV panels became one of the heat sources during the daytime. The combined variations of these factors dominated the water energy balance below FPV panels. The measured data and simulation results serve as a foundation for evaluating the impact of FPV systems on water temperature, energy budget, and aquatic environment, which would also provide a more comprehensive understanding of FPV systems.

Interactive effects of temperature and protein levels on the growth performance, proximate composition, digestive enzyme activity and serum biochemistry of Labeo rohita.

The current study was performed to investigate the impact of different temperatures and protein levels on the growth performance, proximate composition and digestive and hepatic enzyme activities of Labeo rohita fingerlings. For this purpose, healthy fingerlings (average initial weight of 6.40 ± 0.02 g) were acclimatized for 15 days, then reared at three temperatures (25°C, 30°C and 35°C) and fed three levels of crude protein (25%, 30% and 35% crude protein (CP)) twice daily until satiation for 60 days. The results of the study revealed that the highest growth performance was observed in fish fed 35% protein and reared at 30°C. Similarly, fish reared at 35°C and 25°C water temperature showed comparatively better growth performance in fish fed with 35% protein. Furthermore, a significant enhancement in feed intake was observed with increasing culture temperature and increasing CP levels, but at 25°C, increasing CP levels significantly decreased the feed intake. Sligh variations were also observed in proximate composition in terms of moisture, CP, crude fat (CF) and ash contents in fish fed with different CP levels and reared at different temperatures. The hepatosomatic index and viscerosomatic index decreased significantly with increasing levels of protein and temperature. Amylase activities were significantly reduced with increasing culture temperature at each protein level. Increasing culture temperature did not affected the lipase activities. However, lipase activities were enhanced with increasing CP levels at 25°C and activities decreased with increasing CP levels at 30-35°C. Protease activity was enhanced with increasing temperature and CP levels. Significant increases were also observed in serum total proteins and liver functioning enzymes such as alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase in response to increased temperature, and protein had a reciprocal effect. It is concluded that increasing the CP levels increased the growth performance independent of temperature. However, similar growth performance at 30 CP (30°C) and 35 CP (35°C) indicates that L. rohita requires more protein at higher temperature for optimum growth.

Climate change impacts on eutrophication in the Po River (Italy): Temperature-mediated reduction in nitrogen export but no effect on phosphorus.

Rivers worldwide are under stress from eutrophication and nitrate pollution, but the ecological consequences overlap with climate change, and the resulting interactions may be unexpected and still unexplored. The Po River basin (northern Italy) is one of the most agriculturally productive and densely populated areas in Europe. It remains unclear whether the climate change impacts on the thermal and hydrological regimes are already affecting nutrient dynamics and transport to coastal areas. The present work addresses the long-term trends (1992-2020) of nitrogen and phosphorus export by investigating both the annual magnitude and the seasonal patterns and their relationship with water temperature and discharge trajectories. Despite the constant diffuse and point sources in the basin, a marked decrease (-20%) in nitrogen export, mostly as nitrate, was recorded in the last decade compared to the 1990s, while no significant downward trend was observed for phosphorus. The water temperature of the Po River has warmed, with the most pronounced signals in summer (+0.13°C/year) and autumn (+0.16°C/year), together with the strongest increase in the number of warm days (+70%-80%). An extended seasonal window of warm temperatures and the persistence of low flow periods are likely to create favorable conditions for permanent nitrate removal via denitrification, resulting in a lower delivery of reactive nitrogen to the sea. The present results show that climate change-driven warming may enhance nitrogen processing by increasing respiratory river metabolism, thereby reducing export from spring to early autumn, when the risk of eutrophication in coastal zones is higher.

Molecular mechanisms underlying the vulnerability of Pacific abalone (Haliotis discus hannai) to Vibrio harveyi infection at higher water temperature.

Climate change is one of the most important threats to farmed abalone worldwide. Although abalone is more susceptible to vibriosis at higher water temperatures, the molecular mode of action underlying this has not been fully elucidated. Therefore, this study aimed to address the high susceptibility of Halitotis discus hannai to V. harveyi infection using abalone hemocytes exposed to low and high temperatures. Abalone hemocytes were divided into four groups, 20C, 20 V, 25C, and 25 V, depending on co-culture with (V)/without (C) V. harveyi (MOI = 12.8) and incubation temperature (20 °C or 25 °C). After 3 h of incubation, hemocyte viability and phagocytic activity were measured, and RNA sequencing was performed using Illumina Novaseq. The expression of several virulence-related genes in V. harveyi was analyzed using real-time PCR. The viability of hemocytes was significantly decreased in the 25 V group compared to cells in the other groups, whereas phagocytic activity at 25 °C was significantly higher than at 20 °C. Although a number of immune-associated genes were commonly upregulated in abalone hemocyte exposed to V. harveyi, regardless of temperature, pathways and genes regarding pro-inflammatory responses (interleukin-17 and tumor necrosis factor) and apoptosis were significantly overexpressed in the 25 V group compared to the 25C group. Notably, in the apoptosis pathway, genes encoding executor caspases (casp3 and casp7) and pro-apoptotic factor, bax were significantly up-regulated only in the 25 V group, while the apoptosis inhibitor, bcl2L1 was significantly up-regulated only in the 20 V group compared to the control group at the respective temperatures. The co-culture of V. harveyi with abalone hemocytes at 25 °C up-regulated several virulence-related genes involved in quorum sensing (luxS), antioxidant activity (katA, katB, and sodC), motility (flgI), and adherence/invasion (ompU) compared to those at 20 °C. Therefore, our results showed that H. discus hannai hemocytes exposed to V. harveyi at 25 °C were highly stressed by vigorously activated inflammatory responses and that the bacterial pathogen overexpressed several virulence-related genes at the high temperature tested. The transcriptomic profile of both abalone hemocytes and V. harveyi in the present study provide insight into differential host-pathogen interactions depending on the temperature conditions and the molecular backgrounds related to increased abalone vulnerability upon global warming.

Hypothesised life cycle adaptation of stonefly (Plecoptera) in response to increased water temperatures.

Water temperature is the most important and critical factor for freshwater invertebrates and it fluctuates with an increase in air temperature. In this study, the effect of water temperature on egg development was clarified in Stavsolus japonicus, and the response to climate change in stoneflies with long egg periods were considered. Water temperatures prior to 43 days before hatching likely do not affect egg development in Stavsolus japonicus. Instead, they use egg diapause as an adaptive strategy to survive hot summer conditions. Increased water temperatures may cause migration to higher elevations for stoneflies that have lower adaptability in their egg development period, with populations eventually becoming stranded where no higher elevation or cooler habitat is available. Species extinction is expected to increase with increasing temperatures, leading to reduced biodiversity in many ecosystems. Indirect effects of water warming on maturation and reproduction may lead to substantial reductions in benthic invertebrate populations.

Effect of thermo-velocity barriers on fish: influence of water temperature, flow velocity and body size on the volitional swimming capacity of northern straight-mouth nase (Pseudochondrostoma duriense).

Water temperature and flow velocity directly affect the fish swimming capacity, and thus, both variables influence the fish passage through river barriers. Nonetheless, their effects are usually disregarded in fishway engineering and management. This study aims to evaluate the volitional swimming capacity of the northern straight-mouth nase (Pseudochondrostoma duriense), considering the possible effects of water temperature, flow velocity and body size. For this, the maximum distance, swim speed and fatigue time (FT) were studied in an outdoor open-channel flume in the Duero River (Burgos, Spain) against three nominal velocities (1.5, 2.5 and 3 m s-1 ) and temperatures (5.5, 13.5 and 18.5°C), also including the changes between swimming modes (prolonged and sprint). Results showed that a nase of 20.8 cm mean fork length can develop a median swim speed that exceeds 20.7 BL s-1 (4.31 m s-1 ) during a median time of 3.4 s in sprint mode, or 12.2 BL s-1 (2.55 m s-1 ) for 23.7 s in prolonged mode under the warmest scenario. During prolonged swimming mode, fish were able to reach further distances in warmer water conditions for all situations, due to a greater swimming speed and FT, whereas during sprint mode, warmer conditions increased the swim speed maintaining the FT. In conclusion, the studied temperature range and flow velocity range influence fish swimming performance, endurance and distance travelled, although with some differences depending on the swimming mode. The provided information goes a step forward in the definition of real fish swimming capacities, and in turn, will contribute to establish clear passage criteria for thermo-velocity barriers, allowing the calculation of the proportion of fish able to pass a barrier under different working scenarios, as well designing of the optimized solutions to improve the fish passage through river barriers.

Timing and water temperature of drip irrigation regulate cotton growth and yield under film mulching in arid areas of Xinjiang.

BACKGROUND: Cotton (Gossypium hirsutum L.) is the fiber crop most widely cultivated globally and one of the most important commercial crops in China, irrigation is closely related to the growth of cotton. A water temperature for irrigation that is too low or too high inhibits cotton growth. Poor irrigation timing results in water and nutrient deficiencies that reduce cotton yield. Therefore, it is necessary to determine the appropriate irrigation timing and water temperature. METHOD: We conducted an experiment in an arid region of north-western China to assess the effects of irrigation timing and water temperature on soil temperature and the photosynthetic characteristics, biomass, total nitrogen (N), and seed cotton yield. Two irrigation times (daytime and nighttime) and four water temperatures (15, 20, 25, and 30 °C) were combined into eight treatments. RESULTS: Our results showed that water warming and nighttime irrigation improved the photosynthesis, biomass, N concentration (the proportion of total N weight in the plant biomass, in g kg-1 ), N content (the mass of total N, in g plant-1 ), and cotton yield. The optimal water temperature range for photosynthesis was 25.7-28.7 °C. Water warming also boosted the biomass allocation to the stem and increased the N allocation to the stem and leaf. Nighttime irrigation enhanced these phenomena. Water warming also increased the number of bolls per plant but reduced the single boll weight, increasing the seed cotton yield by 5.88-11.46%. At the same water temperature, irrigation during the night increased the number of bolls per plant and the single boll weight, improving the seed cotton yield by 2.95-4.31%. Among them, NI25 (nighttime irrigation with 25 °C water temperature) increased the yield by 14.13-14.90% compared with CK (daytime irrigation with 15 °C water temperature), which offers the best combination for increasing the yield. CONCLUSION: Our study clarifies the optimal irrigation timing and water temperature for cotton production under drip irrigation with film mulching, providing valuable information for improving the cotton yield in arid areas with temperate continental climate. © 2023 Society of Chemical Industry.

Surface Measure to Depth (SMeTD): a new low-budget system for 3D water temperature measurements for combining with UAV-based thermal infrared imagery.

Characterising spatial patterns in water temperature is important for monitoring aquatic habitats and understanding physical and biogeochemical processes to support environmental management decisions. As freshwater bodies exhibit high spatial and temporal variability, high-resolution 3D temperature data are essential to understand local anomalies. The acquisition of simultaneously high spatial and temporal datasets in the field has so far been limited by costs and/or workload associated with commonly used monitoring systems.We present a new, low-cost, spatially and temporally flexible 3D water temperature monitoring system, Surface Measures to Depth (SMeTD). SMeTD can be used to provide information on the relation of water surface temperature to changes with depth, characterise water temperature in 3D and ground truth remotely sensed thermal infrared data. The systems performance was tested under laboratory conditions and under controlled conditions in the field. This revealed an accuracy comparable to established but more expensive monitoring systems. Field testing of SMeTD involved 1-min data collection of 3D water temperature for a full diurnal cycle in a lake. The 3D temperature patterns were supported by a thermal infrared image of the lakes surface. The field dataset demonstrated higher water temperatures and higher water temperature variation at the surface compared to deeper layers. SMeTD can be used to observe a broad range of hydrological processes in natural and artificial aquatic environments and help to understand processes involved with energy budgets, infiltration, limnology, or groundwater surface water exchange.

Effects of different regimes of low temperature on egg hatching of Dactylogyrus vastator (Monogenea: Dactylogyridae).

The development of dactylogyrids is dependent on water temperature, and their eggs fail to hatch below 5 °C. In the field, however, mean abundance of Dactylogyrus species increases and reaches a high level in winter, which suggests that infective oncomiracidia hatch from eggs in winter. Therefore, the effect of low water temperature on in vitro egg hatching of D. vastator was determined in laboratory. D. vastator hatching success was 65.3%, 62.7%, 42.6% and 22.3% when eggs were firstly incubated for 0, 7, 14 and 21 days at 5 °C and then consecutively maintained for 15 days at 20 °C. When eggs were directly incubated at 5 °C, eggs failed to hatch within one month. However, hatching success was 69.8% and 66.7%, respectively, when maintained at 5 °C after 12 and 24 h incubation at 20 °C. The results suggested that egg incubation for more than 1 week at 5 °C had significant impacts on hatching success of D. vastator subsequently maintained at 20 °C. But low temperature (5 °C) had no effect on hatching success when eggs were firstly exposed to room temperature (20 °C) for one day.

Environmental factors associated with the filamentous green algae Cladophora blooms: A mesocosm experiment in a shallow eutrophic lake.

The process of ecological restoration in eutrophic lakes, often results in the blooming of the filamentous green algae Cladophora. This consequently affects the growth of submerged plants and the restoration of vegetation. However, the blooming process of Cladophora and the environmental factors affecting their growth are poorly understood. This has become a difficult problem in the management of lakes. The study therefore focused on succession process of Cladophora blooms and their driving factors through mesocosm experiments in Caohai Lake. The results of our experiment indicated that Cladophora growth was mainly affected by water temperature, turbidity and soluble reactive phosphorus concentration of the habitat where Elodea nuttallii and Cladophora coexist. Nuisance Cladophora was mainly affected by turbidity (>19.24 NTU) when the water temperature was above 15.7 °C. With increasing Cladophora biomass and decreasing turbidity (<4.88 NTU), Cladophora biomass accumulation was mainly limited by the soluble reactive phosphorus concentration (<3.2 µg/L). Recorded turbidity range of 9.54-13.19 NTU was found to cause dramatic changes in the biomass of Cladophora. The results also showed that the outbreak of Cladophora blooms was mainly attributed to turbidity when the water temperature was appropriate in eutrophic lakes. These findings suggest that successful management efforts should strengthen the monitoring of transparency change in addition to controlling the phosphorus concentration to limit the Cladophora overgrowth on lake ecological restoration.

A copula model to identify the risk of river water temperature stress for meteorological drought.

Drought is a natural phenomenon that can occur in all climatic zones, and is persistent and regionally widespread. Extreme drought caused by climate change can have serious consequences for freshwater ecosystems, which can have significant social and economic impacts. In this study, the effect of meteorological drought on river water temperature was analyzed probabilistically in order to identify the risk of river water temperature stress experienced by the aquatic ecosystem when a meteorological drought occurs. Meteorological drought is divided into a situation in which moisture is insufficiently supplied from the atmosphere and a situation in which the atmosphere requires excessive moisture from the earth's surface. Using the copula theory, a joint probabilistic model between the river water temperature and each meteorological drought caused by two causes is proposed. In order to consider the propagation time from meteorological drought to river water temperature, the optimal time-scale meteorological drought index is adopted through correlation analysis between the meteorological drought index calculated at various time-scales and the river water temperature. The optimal copula function of the drought index and river water temperature is determined using AIC analysis. Using the proposed model, a risk map is drawn for the river water temperature stress experienced by the aquatic ecosystem under the user-defined meteorological drought severity. The risk map identifies the stream sections where the river water temperature is relatively more sensitive to meteorological drought. The identified stream sections appear differently depending on the cause of the meteorological drought, the region, and the season.

High water temperature raised the requirements of methionine for spotted seabass (Lateolabrax maculatus).

This study evaluated the effects of dietary methionine level and rearing water temperature on growth, antioxidant capacity, methionine metabolism, and hepatocyte autophagy in spotted seabass (Lateolabrax maculatus). A factorial design was used with six methionine levels [0.64, 0.85, 1.11, 1.33, 1.58, and 1.76%] and two temperatures [moderate temperature (MT): 27 ℃, and high temperature (HT): 33 ℃]. The results revealed the significant effects of both dietary methionine level and water temperature on weight gain (WG) and feed efficiency (FE), and their interaction effect was found on WG (P < 0.05). In both water temperatures tested, fish WG increased with increasing methionine level up to 1.11% and decreased thereafter. The groups of fish reared at MT exhibited dramatically higher WG and FE than those kept at HT while an opposite trend was observed for feed intake. Liver antioxidant indices including reduced glutathione and malondialdehyde (MDA) concentrations, and catalase and superoxide dismutase (SOD) activities remarkably increased in the HT group compared to the MT group. Moreover, the lowest MDA concentration and the highest SOD activity were recorded at methionine levels between 1.11% and 0.85%, respectively, regardless of water temperatures. Expression of methionine metabolism-related key enzyme genes (mat2b, cbs, ms, and bhmt) in the liver was increased at moderate methionine levels, and higher expression levels were detected at MT compared to HT with the exception of ms gene relative expression. Relative expression of hepatocyte autophagy-related genes (pink1, atg5, mul1, foxo3) and hsp70 was upregulated by increasing methionine level up to a certain level and decreased thereafter and increasing water temperature led to significantly enhanced expression of hsp70. In summary, HT induced heat stress and reduced fish growth, and an appropriate dietary methionine level improved the antioxidant capacity and stress resistance of fish. A second-order polynomial regression analysis based on the WG suggested that the optimal dietary methionine level for maximum growth of spotted seabass is 1.22% of the diet at 27 ℃ and 1.26% of the diet at 33 ℃, then 1.37 g and 1.68 g dietary methionine intake is required for 100 g weight gain at 27 ℃ or 33 ℃, respectively.

Coastal planktonic community unaffected by Boreal hydropower complex in Québec, Canada.

Comprehensive studies of the impact of hydropower on coastal environments are rare. This study examines the impact of commissioning the hydropower plants of the Romaine complex on the freshwater discharge of the Rivière Romaine near its estuary and on the Chenal de Mingan ecosystem in the summers of 2015, 2017 and 2019. Continuous temperature, salinity and chlorophyll a data were obtained from two instrumented buoys, and nutrients as well as the phytoplankton and zooplankton communities were sampled five times a year at 11 stations. The results demonstrate the major influence of offshore waters on temperature and salinity in the study area, and the decreasing influence of the Rivière Romaine with distance from its mouth. Nutrient concentrations in the estuary did not covary with river discharge or with nutrient concentrations in the river. Importantly, impoundment of the reservoirs of the complex had no measurable effect on nutrient stoichiometry in the Chenal de Mingan. Overall, the chlorophyll a concentrations ranged from 0.1 to 7.6 µg L-1 in the channel, the community was dominated by diatoms, and phytoplankton growth was either nitrate limited or under predation pressure. The zooplankton community has been composed of the same groups of species and has been dominated by cyclopoids and calanoids since 2015. Our study underlines the importance of including regional meteorological trends in the analysis to avoid biased conclusions on the impact of hydropower projects. The study concluded that modulation of the Rivière Romaine discharge and related changes in water quality did not lead to measurable change in plankton production in the Chenal de Mingan.

Performance and validation of water surface temperature estimates from Landsat 8 of the Itaipu Reservoir, State of Paraná, Brazil.

Studies on water surface temperature (WST) from thermal infrared remote sensing are still incipient in Brazil, and for many water resources, they do not exist. Many algorithms have been developed to estimate surface temperature in satellite images. There are also many difficulties in implementing these algorithms due to their complexity, especially in free software, which restricts the satisfactory processing of these data by users of the technique. Thus, this work aimed to validate an algorithm used to estimate land surface temperature (LST) when applied to the surface of inland water bodies. Water surface temperature estimates (WSTe) were generated from Itaipu State of Paraná (PR) reservoir, Brazil, calculated from Landsat 8 - TIRS satellite images (WSTs) and water surface temperature data from 37 in situ stations (WSTi). A linear regression model of the WSTe was generated in 60% of the samples and its validation with the remaining 40%, subject to prior evaluation of some statistical indicators. The model was considered significant since the coefficient of determination (r2) was 0.90 (95% of confidence), root mean square deviation (RMSD) 0.8 °C, Willmott Index (d) = 0.97, and Nash-Sutcliffe efficiency coefficient (NSE) = 0.89. The methodology used to extract WSTs from the Python QGIS plugin was relatively quick to apply, easy to understand, and had a better performance of the estimates than those presented in the literature review.

Investigating the causes of reduced dissolved oxygen concentrations in Kickapoo Creek, TX.

Excessive organic matter and nutrients can depress dissolved oxygen concentration (DOC) in streams. The aim of this study was to understand the depressed DOC of Kickapoo Creek in Texas, USA, which is an impaired stream; identify the possible sources causing the depressed DOC and elevated Escherichia coli levels; and identify possible remedial measures. Monthly grab water quality data was monitored for nine stations in the watershed. For three of the nine stations, 24-h DOC was also monitored for a comparison with the minimum and average DOC criteria. Correlational, graphical, spatial, and temporal analyses were carried out for DOC concentration with other water quality variables which have the potential to depress DOC in the stream. The correlational analyses show a weak to moderate correlation for DOC with nutrient and oxygen-demanding substance concentrations present in the stream. However, there are spatial and temporal trends in DOC data that can be attributed to the nutrient influx into the stream. A pattern of increasing nutrient concentrations from upstream to downstream partially explains the decreasing dissolved oxygen (DO) concentrations observed towards the lower reaches. Visual interpretations of riparian vegetation and sediment influx also support the spatial patterns in DO concentrations. The majority of the depressed DOC occurs in the summer months when streamflow is at a minimum. The depressed DOC during summer is partially explained by the increasing daily temperatures for the summer months as revealed by the trend analysis of the daily temperature data from 1981 to 2020 using the modified Mann-Kendall test, Pettitt test, and Sen's slope.

Relationship between Water Temperature and Floating Time of Aquatic Cadavers.

OBJECTIVES: To study the relationship between water temperature and floating time of aquatic cadavers, providing a reference for more precise positioning and searching for floating corpses. METHODS: The floating model of guinea pig after drowning at 17-30 ℃ was established, and the floating times of carcasses were recorded. The collected data of 32 floating corpse cases in the Pearl River were sorted out and analyzed according to the floating time of corpses corresponding to each degree of water temperature. The relationship models between water temperature and the floating time of guinea pig carcass, and between that and the floating time of real cases were established. RESULTS: The floating time of the cadaver was negatively correlated with water temperature. The power function fitting equation of the relationship between floating time and water temperature of guinea pig carcass was y=1×1015x-10.530(R2=0.871, P<0.01), and the power function fitting equation of the relationship between corpse floating time and water temperature was y=3×106x-3.467(R2=0.802, P<0.01). CONCLUSIONS: It is found that average floating cadaver time has a power function with water temperature, which provides a reference for locating floating cadavers and establishing search models.

Development of inclined plate honey moisture reduction system.

Honey is delicious, nutritious and has high medicinal value in comparison to other sweeteners. Honey is usually extracted from comb as immature product which results in high moisture which makes it more liable to be fermented by osmophilic yeasts. So, it needs to be processed for moisture reduction, to delay crystallization and to overcome the problem of fermentation. In the present investigation, a honey moisture reduction system was developed and tested to reduce the moisture content of honey to about 17%. The system consisted of a flat plate inclined at an angle. The plate was heated from the underside and honey for moisture reduction was re-circulated over it until desired moisture content was achieved. Experiments were conducted for honey moisture reduction at water temperature of 40-70 °C with plate inclinations of 30°-60° according to four level full factorial design of experiment. The results showed that the total reduction time required for reaching moisture content of about 17% varied with water temperature and angle of inclination. The moisture reduction time required for reaching a moisture content of 17 percent at 40 °C was about five times the time required at 70 °C. The energy cost of honey moisture content reduction from 21.5 to 17% was Rs. 4.7 to Rs. 12.5 per kg.

Water storage decisions will determine the distribution and persistence of imperiled river fishes.

Managing the world's freshwater supply to meet societal and environmental needs in a changing climate is one of the biggest challenges for the 21st century. Dams provide water security; however, the allocation of dwindling water supply among reservoirs could exacerbate or ameliorate the effects of climate change on aquatic communities. Here, we show that the relative sensitivity of river thermal regimes to direct impacts of climate change and societal decisions concerning water storage vary substantially throughout a river basin. In the absence of interspecific interactions, future Colorado River temperatures would appear to benefit both endemic and nonnative fish species. However, endemic species are already declining or extirpated in locations where their ranges overlap with warmwater nonnatives and changes in water storage may lead to warming in some of the coolest portions of the river basin, facilitating further nonnative expansion. Integrating environmental considerations into ongoing water storage negotiations may lead to better resource outcomes than mitigating nonnative species impacts after the fact.

How does elevated water temperature affect fish brain? (A neurophysiological and experimental study: Assessment of brain derived neurotrophic factor, cFOS, apoptotic genes, heat shock genes, ER-stress genes and oxidative stress genes).

Water temperature is one of the most important environmental factors affecting the growth and survival of fish. Increased water temperature became a global problem and it is estimated that there will be an increase in water temperature due to global climate change. The physiological mechanism for the effects of high water temperature on the fish brain is not fully known. In the present study, fish were exposed to different temperatures (10 °C/15 °C/20 °C/25°) and brain tissues were sampled 2 h-4h-6h-8h per hour respectively and then we investigated transcriptional changes of BDNF, cFOS, apoptotic genes (caspase 3, Bax, Bcl2), heat shock genes (Hsp70 and Hsp 90) ER-Stress genes (grp78, atf6, and ire1) and oxidative stress genes (CAT, SOD, and GPx) and also immunoflourescence changes of BDNF and cFOSin rainbow trout brain. The results indicated that high temperature stress lead to physiological changes in the fish brain by causing a decrease in mRNA expression levels of CAT, SOD, GPx and Bcl2 and by causing an increase in mRNA expression of BDNF, cFOS, apoptotic genes (caspase 3, Bax), heat shock genes (Hsp70 and Hsp 90) ER-Stress genes (grp78, atf6, and ire1). This study will provide important information to elucidate the physiological mechanisms related to the effects of high water temperature on the fish brain.