Influence Of Water Temperature Research Articles

Effects of Rearing Temperature on Growth and Survival of Blackthroat Seaperch, Doederleinia berycoides (Hilgendorf, 1879), Post-Flexion Larvae and Juveniles

In post-flexion larval and juvenile stages of hatchery-reared blackthroat seaperch Doederleinia berycoides (Hilgendorf, 1879), the influence of water temperature on growth and survival was examined to identify the optimal rearing temperatures. Temperature treatments were conducted separately for pelagic post-flexion larvae (32 days post hatching [dph]) and settled juveniles (69 dph). Fish were transferred to four replicate 30 L tanks (30 larvae or 15 juveniles per tank) and reared for 15 days under five temperatures (13, 16, 19, 22 and 25 °C) maintained by using heaters and coolers. The mean survival rates (± SD) of post-flexion larvae were high (>73 %) for all temperatures (13 °C: 73.3 ± 6.9 %, 16 °C: 76.7 ± 6.8 %, 19 °C: 80.8 ± 10.7 %, 22 °C: 79.2.7 ± 2.8 %, 25 °C: 71.7 ± 4.4 %). Growth increased at higher temperatures and was significantly faster at 22 and 25 °C (P < 0.05) than lower temperatures. For juveniles, mean survival rates were significantly higher at 16–25 °C (>90%: 16 °C: 91.7 ± 1.7 %, 19 °C: 95.0 ± 3.2 %, 22 °C: 91.7 ± 1.7 %, 25 °C: 91.7 ± 5.0 %) than at 13 °C (71.7 ± 7.9 %) (P < 0.05). Juvenile growth, like that of post-flexion larvae, was faster at 22 and 25 °C. These results suggest that maintaining a high rearing temperature (22–25 °C) is important for enhancing the growth for post-flexion larvae and juveniles of blackthroat seaperch and reducing the rearing period to the size of release seedlings.

Nitrogen reducing mechanism by microporous aeration based on microbial population characteristics: water temperature factor

ABSTRACT The formation of black odour water is primarily attributed to the elevated concentration of organic pollutants, along with an excessive amount of nitrogen and phosphorus, ultimately leading to an anoxic aquatic environment. The water temperature influence mechanism on black-odorous water restoration by microporous aeration is still lacking depth study. This paper selected (15–18) ℃ (spring and autumn), (22–25) ℃ (summer), (8–11) ℃ (winter) as temperature conditions, and investigated temperature influence on nitrogen reduction. Researches showed that: (1) The removal rates of COD, NH4 +-N and TN were significantly positively correlated with temperature (r = 0.99, 0.96, 0.97), the lowest removal rates were 83.16%, 95.68%, 58.7% ((8–11) ℃), the highest values were 92.67%, 98.27%, 70.96% ((22–25) ℃), respectively. (2) At a temperature range of 22–25°C, the microbial community exhibited the highest levels of abundance, diversity, and uniformity. Notably, Proteobacteria dominated this temperature range with a relative abundance of 79.72%. Furthermore, temperature positively correlated with the majority of dominant bacterial species, suggesting that conditions at 22–25°C are highly conducive to the growth of most bacterial communities. Among these, Limnohabitans, Alsobacter, and Candidatus_Aquirestis, which possess key functions in denitrification and nitrogen removal, displayed significantly higher abundances. It explains the positive correlation between temperature and removal rates of COD, TN and NH4 +-N from microbial population’s perspective. Thus, the best temperature for repairing black-smelly water is (22–25) ℃. This study provides technical reference for mechanism research and practical application of microporous aeration.

Thermal structure variations and influence factors in a subtropical reservoir, China: explanations from multiple research methods

ABSTRACT Revealing the subtle variations in thermal structure in a reservoir is crucial for accurately understanding the interaction between water and the carbon cycle. This study provides a detailed description of the thermal structure of Dalongdong reservoir, a representative subtropical stratified reservoir in Guangxi, China. It unveils the three stable state changes in water – mixing, microstratification, and stratification – along with their influencing factors. The study emphasizes air temperature (AT) as the primary factor influencing water temperature (WT) stability, followed by water level. Cross-correlation analysis shows that adjacent WTs experience a prolonged response hysteresis during the stratification period, while the mixing period exhibits a shorter hysteresis. Wavelet analysis revealed that AT and surface-layer WT exhibited a dominant oscillation period of 16–32 h. The periodicity of other water layers is not obvious. This framework can help to enhance our understanding of material cycles and protection of the water environment.

Thermal modulation of energy allocation during sex determination in the European sea bass (Dicentrarchus labrax)

Water temperature governs physiological functions such as growth, energy allocation, and sex determination in ectothermic species. The European sea bass (Dicentrarchus labrax) is a major species in European aquaculture, exhibiting early dimorphic growth favoring females. The species has a polygenic sex determination system that interacts with water temperature to determine an individual’s sex, with two periods during development that are sensitive to temperature. The current study investigated the influence of water temperature on energy allocation and sex-biased genes during sex determination and differentiation periods. RNA-Sequencing and qPCR analyses were conducted in two separate experiments, of either constant water temperatures typical of aquaculture conditions or natural seasonal thermal regimes, respectively. We focused on eight key genes associated with energy allocation, growth regulation, and sex determination and differentiation. In Experiment 1, cold and warm temperature treatments favored female and male proportions, respectively. The RNA-seq analysis highlighted sex-dependent energy allocation transcripts, with higher levels of nucb1 and pomc1 in future females, and increased levels of egfra and spry1 in future males. In Experiment 2, a warm thermal regime favored females, while a cold regime favored males. qPCR analysis in Experiment 2 revealed that ghrelin and nucb1 were down-regulated by warm temperatures. A significant sex-temperature interaction was observed for pank1a with higher and lower expression for males in the cold and warm regimes respectively, compared to females. Notably, spry1 displayed increased expression in future males at the all-fins stage and in males undergoing molecular sex differentiation in both experimental conditions, indicating that it provides a novel, robust, and consistent marker for masculinization. Overall, our findings emphasize the complex interplay of genes involved in feeding, energy allocation, growth, and sex determination in response to temperature variations in the European sea bass.

A circumpolar study of surface zooplankton biodiversity of the Southern Ocean based on eDNA metabarcoding

Under pressure from climate change and fishing, the Southern Ocean ecosystems have been changing. Zooplankton plays a vital role in the food web of the Southern Ocean and is crucial for maintaining ecosystem stability. Investigating the circumpolar-scale species composition and biodiversity of zooplankton is crucial for ensuring ecosystem-based conservation and management of the Southern Ocean in a changing climate. Here, we utilized eDNA metabarcoding to assess the biodiversity of zooplankton in the surface seawater surrounding the Antarctica based on samples collected during two expeditions spanning from 2021 to 2022. The main purpose of this paper is to provide more baseline information about circumpolar zooplankton biodiversity based on the emerging eDNA metabarcoding tool. This comprehensive approach led to the identification of over 300 distinct zooplankton species, forming a diverse community dominated by Jellyfish, Mollusca and Polychaete. Surprisingly, common dominant taxonomic groups such as krill and copepods in the Southern Ocean did not show high relative abundance (reads) in surface seawater. The results of redundancy analysis (RDA) and correlation analysis highlighted that water temperature and chlorophyll a had the most significant impact on the reads and diversity of zooplankton. Notably, the influence of water temperature on zooplankton seemed to be primarily indirect, potentially mediated by its effects on primary productivity. Increasing in primary production might lead to lower zooplankton biodiversity in the Southern Ocean in future. This research underscores the effectiveness of eDNA metabarcoding as a valuable tool for monitoring zooplankton diversity in open seas. Given the ongoing changes in temperature, sea ice extent and their impact on primary production, our findings lay a crucial foundation for using eDNA techniques to establish long-term biodiversity monitoring programs across extensive marine ecosystems in the future.

Effects of water temperature on soil aggregate stability between soils developed from different parent materials in the subtropical hilly area of China

Water temperature has an important effect on soil aggregate stability. In this study, six soils derived from different parent materials in the hilly region of southern China were selected, and the mean weight diameter (MWD), geometric mean diameter (GMD), and soil erodibility (K value) were measured under different water temperature conditions. The aim of this study was to investigate the influence of water temperature on soil aggregate stability and erodibility. As the water temperature increased from 5 °C to 40 °C, the average content of >5 mm water-stable aggregates decreased by 57.13 %, while the average content of <0.25 mm water-stable aggregates increased by 214.41 %. The MWD and GMD of the six different parent soil types exhibited a decreasing trend with increasing water temperature. The trend of the K value was opposite to that of these values. The influence of water temperature on soil aggregate stability is mainly attributed to the thermal effect on the viscosity of soil water and the expansion of clay minerals. As the water temperature increases, the water viscosity coefficient, water density and water surface tension gradually decrease. Moreover, the response of soil aggregate stability and erosion resistance to water temperature varies with soil depth and parent material type. The topsoil exhibits greater sensitivity to water temperature than does the subsoil. Shale (SH) soils and quartz sandstone (QS) soils exhibited higher sensitivities, and Quaternary red clay (QRC) soils exhibited the lowest sensitivity to water temperature among the six soils. This difference is mainly attributed to differences in the contents of expansive clay minerals and organic matter. These results indicate that soil aggregate stability and erosion resistance decrease with increasing water temperature, which may be one reason for severe soil erosion under extremely high temperature and rainfall conditions in the southern red soil hilly region during summer.

Physiological effects of interacting native and invasive bivalves under thermal stress

Across many ecosystems in North America and Europe, native freshwater bivalves (Order Unionida) are threatened by fouling and competition for food by the invasive zebra mussel Dreissena polymorpha. In light of climate change, knowledge on the influence of water temperature on these competitive effects is important, yet poorly understood. This study examines the physiological impact of the interaction between D. polymorpha and the native European unionid Anodonta cygnea over a 28 day—period in response to water temperatures of 12, 19, and 25 °C by comparing their glycogen, glucose, lipid and protein concentrations. The laboratory experiment comprised three treatments: (1) fouling of A. cygnea by D. polymorpha, (2) both species present but not fouling; and (3) a control in which A. cygnea and D. polymorpha were placed separately. Increased water temperatures caused physiological stress in D. polymorpha as evident from reduced glycogen, glucose, lipid and protein concentrations. Dreissena polymorpha benefited from fouling of unionids, as individuals that fouled A. cygnea tended to have increased glycogen, glucose, lipid and protein concentrations. Competitive effects of D. polymorpha over the unionid bivalve species, however, were not intensified by elevated temperatures. Glochidia release, lower infestation intensity, and physiological stress of Dreissena at higher temperatures were likely confounding factors. The results of this study suggest that understanding the physiological consequences of species interactions at changing temperatures can be an important tool to assess future climate change impacts on freshwater bivalves and aquatic community structures.

Evaluation of Post-Surgical Recovery in Olive Flounder (Paralichthys olivaceus) by Assessing Behavior, Heart Rate, and Wound Healing

This study examined the post-surgery recovery of olive flounder (Paralichthys olivaceus) following tag insertion by analyzing behavior, heart rate, and wound healing. The experiments used 30 individuals (length: 38.67 ± 2.12 cm; weight: 742.48 ± 116.41 g). Heart rate was measured using a DST milli-HRT (Star-Oddi) bio-logger. To assess the influence of water temperature on the recovery process after surgical tag insertion, behavioral analyses, heart rate, and wound healing were conducted in two experimental groups: Experiment 1 (22 °C, optimal water temperature); Experiment 2 (28 °C, high water temperature); and control group (22 °C, non-operated fish). The experiment was repeated twice over a 7-day period for each experimental group. Compared to the non-operated fish, the operated fish exhibited stable levels after the 3rd to 4th day in Experiment 1. Statistical analyses based on heart rate in Experiment 1 indicated that the appropriate post-surgery recovery time point was approximately 3 days, representing the point at which behavioral fluctuations stabilized. In the case of Experiment 2, abnormal behavioral patterns (e.g., tilted swimming) and changes in average swimming time and daily heart rate were found to stabilize after 4 days post-surgery.

Sensitivity analysis of underwater launch based on Morris method

The discharge velocity, pressure difference and acceleration of underwater launch performance are affected by many factors, including depth, sailing speed, burning rate, water temperature, density and other operating parameters. The existing underwater launch sensitivity analysis is a local sensitivity qualitative analysis based on single-step perturbation analysis, which can only investigate the influence of a single uncertain factor on the model results in a small range. In this paper, based on the underwater launch model under multi-factor coupling, 10 input parameters were selected to calculate the multi-factor sensitivity of the underwater launch model based on the three objectives of velocity, pressure difference and acceleration at the time of discharge, and the Morris global sensitivity analysis method was used to calculate the sensitivity of the underwater launch model, and the sensitivity of the 10 input parameters to the model results was sorted. The results show that the five input parameters of burning rate, depth, propellant temperature, density and water temperature have the highest sensitivity to velocity, pressure difference and acceleration, and the sensitivity order is slightly different. The influence of water temperature on the three targets is almost evenly distributed in the range of values, and the other parameters have different sensitive ranges for different targets.

Spatial analysis of water quality parameters concentration around the floating solar panel installation in Lake Mahoni, Depok, Indonesia

The transition to renewable energy, specifically solar panels, is increasingly popular. There has been an innovation to place solar panels floating on water. However, floating solar panels (FSP) affect the water quality parameters below them. This study aims to analyze the concentration of water temperature, dissolved oxygen (DO), and biochemical oxygen demand (BOD) spatially in the area surrounding the FSP in Lake Mahoni, examining the influence of air temperature on water temperature as well as the influence of water temperature on DO and BOD. During three weeks of observations, samples were collected from 9 sampling points around the FSP, once a week in the morning and afternoon. Data processing and analysis were performed using descriptive statistical methods, normality tests, comparative tests, correlation tests, and spatial mapping. The highest results indicate DO, BOD, and temperature changes between the upstream area and below the FSP ranged from -1.77 to 0.48 mg/l, -2.68 to 1.78 mg/l, and -0.50 to 0.60°C, respectively. Conversely, the highest changes from below the FSP to the downstream area ranged from -1.55 to 4.54 mg/l, -1.91 to 3.34 mg/l, and -0.30 to 0.80°C, respectively. Water temperature and DO show patterns below the FSPs area, but no pattern is observed in BOD. A significant positive correlation was found between air and water temperature (ρ=0.945, p=0.005). A significant correlation was observed between water temperature and DO (ρ=0.87, p=0.002) and BOD (ρ=0.803, p=0.009) upstream of the FSP in the afternoon. In contrast, there was no significant influence on water temperature, DO, or BOD in the morning (P&gt;0.05) in the upstream area and below the FSP.

Залежність лінійного зростання та виживання личинок субтропiчної прiсноводної креветки (Мacrobrachium nipponense Dе Haan, 1849) від температури і солоності

Purpose. Studies of the growth and survival of Oriental river prawn (Macrobrachium nipponense) larvae depending on water temperature and salinity during cultivation. Methodology. Experimental studies were carried out at the Aquatic Department of Aquatic Bioresources and Aquaculture of the Odesa State Ecological University in 2020-2021. Brood Oriental river prawns (Macrobrachium nipponense) were caught in the lower Dniester river and placed into a 0.8 m3 RAS. The larvae were stocked in separate aquariums with automatically maintained specified temperature regime. The first series of experiments in fresh water investigated the influence of water temperatures of 20–22, 22–24, 24–26, and 28–31°C on the growth of shrimp larvae (from the 1st stage to the Pl stage). Cultivation in water with a salinity of 5, 7, 12 ‰ was carried out at a temperature of 20–22, 22–24, 28–31 °C. Ten prawn larvae were measured daily under a binocular microscope (MBS-10) using an eyepiece-micrometer. The stage of larval development and the survival rate were determined. Water salinity was determined using an ATAGO-100 refractometer, and an Azha-101M thermal oximeter was used to determine the oxygen content in water. Statistical processing of data was carried out in Microsoft Excel. Findings. It was established that at a temperature of 24–26°C, the duration of the transition from one stage of larval development to another in Oriental river prawn (Macrobrachium nipponense) increased as the larvae grew and developed. It lasted 4–5 days in the first stages (1-3), then stages from 6 to 9 days in the later stages. High temperature stimulated the growth of larvae and accelerated their development. In fresh water at a temperature of 29–31°C, the length of postlarvae (Pl) reached 6.69±1.15 mm in 28 days of rearing. Cultivation at high temperature resulted in a significant variation in larval sizes (from 4.4 to 8.6 mm CV–25,27). At lower temperatures (25-27, 22-24 and 20-22°C), the average sizes of prawn postlarvae were smaller (5.83±0.78, 4.56±0.15, 4.43±0.15), and the survival rates increased (46, 49 and 54%, respectively). Survival of larvae was inversely dependent on temperature r = –0.89. It was minimal (32%) at a temperature of 29–31°C. The higher the growing temperature, the lower the output of postlarvae. Water salinity, like temperature, significantly affected the growth, survival and size uniformity of postlarvae. In water with a salinity of 5‰, postlarvae reached their maximum length (6.56±0.15 mm) at a temperature of 29-31 °C. At temperatures of 20-22 and 22-24 °C, the size of the postlarvae did not reliably differ among themselves. The maximum survival of postlarvae (52%) was noted at a temperature of 22-24°. Regardless of water temperature, salinity of 5‰ ensured high uniformity of larvae size (CV: 6.11–9.09). At a salinity of 7‰, the maximum length of postlarvae was reached at a temperature of 29-31oC, and the highest survival rate of prelarvae (34%) was noted at a temperature of 20-22oC. The size of the larvae and their survival at other growing temperature conditions did not differ significantly (Р&lt;95). A salinity of 7‰ also ensured the uniformity of postlarvae sizes (CV: 6.12-8.97). At a salinity of 12‰, high water temperature stimulated the growth of larvae with relative uniformity of their linear sizes, but in all variants of the experiment the survival rate of postlarvae was very low (4–9%). Originality. Experimental data on the growth and survival of larvae of the Oriental river prawn (Macrobrachium nipponense) depending on temperature and salinity are presented for the first time. The influence of the salinity of the environment on the size uniformity of the larvae was established. Practical value. The obtained results can be used for the development and improvement of methods of artificial reproduction and cultivation of the Oriental river prawn (Macrobrachium nipponense) under controlled conditions in recirculation aquaculture systems (RAS).

Insights into Daily Dynamics of Fish Migration during Spring in the Konda River

Hydrology and temperature are known as key drivers for fish migration in floodplain-channel systems of large rivers. The Lower Irtysh contains valuable species of whitefish and sturgeon. Thus, along the Konda River, a complex study was carried out in order to investigate fish migration in spring, with a focus on daily and monthly dynamics. To estimate the number of fish passing up- and downstream, a hydroacoustic system with a scanning beam frequency of 455 kHz was deployed in May 2017. The survey revealed the presence of three peaks in migration activity, as well as differences between a location close to the shore and another in the main channel. Regression analysis revealed a high degree of reliability of the influence of water temperature on the number of migrating fish (p &lt; 0.001). The dataset also showed a daily rhythm of fish migration. An analysis of the daily variation in the illumination index and the intensity of fish migration revealed the presence of noticeable and high correlations for upstream (RS = 0.55; p &lt; 0.05) and downstream migration (RS = 0.71; p &lt; 0.001), respectively. Our data underline the importance of temperature as a trigger for fish migration and reveal diurnal patterns related to illumination.

The Influence of Water Temperature on Seawater Evaporation in the Desalination Process

The Influence of Water Temperature on Seawater Evaporation in the Desalination Process

A simplified method for the thermal performance analysis of double-layer pipe-embedded external wall

Reducing the heat dissipation through the envelope is critical for heating energy savings in buildings. Double-layer pipe-embedded external wall (DPEW) has the advantage of load interception and low-temperature heating, and is a promising solution to reducing energy demand for heating. To gain a comprehensive understanding of the thermal performance of DPEW, a thermal network model is established in this study, which characterizes the steady heat transfer process of DPEW by the superposition of water temperature, outdoor temperature and indoor temperature. The accuracy of the proposed model is validated against experiment data in the literature. Evaluation indexes including equivalent overall heat transfer coefficient (U-value), equivalent outdoor temperature, and energy utilization rate of outer pipe or/and inner pipe are proposed based on the thermal network model of DPEW. A case study is conducted under typical winter conditions of Beijing to investigate the influence of water temperature and outdoor temperature on the thermal performance of DPEW. The results show that the energy utilization rate of DPEW increases with the increasing outdoor temperature and inner pipe water temperature, and the decreasing outer pipe water temperature, while the energy utilization rates of the outer pipe and inner pipe remain largely unaffected. At the outdoor temperature of −9 °C, the outer pipe water temperature of 10 °C and the inner pipe water temperature of 25 °C, the energy utilization rates of the outer pipe, inner pipe, and DPEW reach approximately 27 %, 89 % and 65 %, respectively. This study gives an insight into the steady-state thermal performance of DPEW, and provides guidance for its further research and application.

Production of probiotic powdered barberry (Berberis vulgaris) juice by cast-tape drying technique

Edible seedless barberry (Berberis vulgaris) is an indigenous Persian fruit containing anthocyanins. Drying techniques provide more access of seasonal fruits. Cast-Tape-drying (CTD) is an innovative, safe and competitive drying technology, which employs hot water thermal energy for dehydration. A Central-composite-design was used to investigate the influence of water temperature (75- 95 °C) and Arabic gum concentration (10- 14%) to produce CT-dried powder. Increasing water temperature decreased moisture content, bulk density, total anthocyanin content (TAC) and total phenol content (TPC) and increased hygroscopicity and hausner ratio (P < 0.05). When Arabic gum concentration increased from 10 to 12%, moisture content, hygroscopicity and bulk density decreased while, hausner ratio, TAC and TPC increased (P < 0.05). Increasing both variables resulted in brighter purple color. Microstructure assay revealed dented particles with sharp edges. Glass transition temperature achieved around 63.6 °C. To promote the functionality, Bacillus coagulans IS2 and Lactobacillus plantarum A7 (109 CFU/g) were incorporated in optimized barberry powder and examined under simulated gastrointestinal condition and during storage. The CTD would be able to be used as a novel method producing powdered barberry juice. By utilizing this technique, it is possible preserve the survivability of B.coagulans, while, L.plantarum may require additional strategies to maintain the survivability during drying.

Dynamics of Decapoda larvae communities in a southwest Iberian estuary: Understanding the impact of different thermal regimes

Environmental conditions play a pivotal role in shaping the dynamics of meroplanktonic communities, which represent a vital life stage, crucial for successful recruitment. Specifically, temperature can impact the survival and duration of larval development in decapod crustacean species. The objective of this study is to analyze the community of decapod larvae in the Guadiana estuary, located in southwest Iberia. The analysis focuses on the community's taxonomic composition, temporal variability, and the influence of environmental factors. Particularly, the study emphasizes investigating the impacts of different thermal regimes on the abundance of these assemblages. A comprehensive zooplankton sampling program was conducted at a single station in the lower estuary, from 2014 to 2022. The decapod larvae assemblages are dominated by Upogebia spp., followed by Diogenes pugilator, Panopeus africanus, Afropinnotheres monodi, and Polybius henslowii species. The results of structural equation modeling unveiled a strong influence of water temperature and salinity on the community, while chlorophyll-a concentration, river runoff, and the large-scale climatic mode North Atlantic Oscillation (NAO) revealed no impact on the abundance of these assemblages. Overall, the community and the main taxa displayed a positive linear trend in response to increased salinity. However, the effect of increasing temperature varied among species. In the current climatic scenario, water temperature emerges as a critical factor in predicting seasonal variation of the assemblages' abundances, exhibiting a marked seasonality during spring and summer. Predictive models used to investigate future scenarios, Representative Concentration Pathway (RCP) 2.6 and RCP 8.5, defined by the International Panel on Climate Change (IPCC), where the temperature is expected to rise 2 °C and 4.3 °C by 2100, suggest the possibility for an alteration in assemblages' composition, where the abundances of D. pugilator, the second most abundant species, tend to decrease abruptly. Reported evidence, coupled with the typical Mediterranean climate of the region, where extreme climatic events, like marine heatwaves, are becoming more frequent, the high connectivity with the Mediterranean Sea, where invasion by non-indigenous species is increasing, also connected with changes in freshwater discharges, may trigger significant alterations in species dominance and abundance, with ecological and socio-economic implications.

The effect of climate oscillations on skipjack tuna (Katsuwonus pelamis) in the Indian Ocean

Skipjack tuna (Katsuwonus pelamis) (SKJ) is one of the most commercially important marine fish species distributed throughout the world's tropical and subtropical oceans. The Indian Ocean is a main fishing ground for SKJ, whose exploitation rate is just below the maximum sustainable yield. Therefore, SKJ stocks may potentially be significantly affected by climate change. In this study, climatic oscillation indices related to the Indian Ocean, including the Indian Ocean Dipole (IOD), the mean water temperature anomaly in the Eastern Indian Ocean (EIO) and Western Indian Ocean (WIO), the Madden-Julian Oscillation Index at 80°E (MJO80) and the Arctic Oscillation Index (AOI), were associated with SKJ catch per unit effort (CPUE). This study aimed to understand the effect of these five climatic oscillations on SKJ, with the goal of optimizing the utilization of skipjack tuna in the Indian Ocean. We combined gradient forest analysis (GFA) and generalized additive models (GAMs) to evaluate the importance of each climatic index with a 0–5 year lag on the impact of SKJ CPUE and to establish an optimal prediction model. The GFA results show that MJO80 is the most important climatic index influencing SKJ CPUE, followed by MJO80_1, AOI_2, IOD_4, WIO_2, etc. The best GAM model includes MJO80, AOI_2, and WIO_2, which could be related to the recruitment and larval survival of SKJ by influencing water temperature. Meanwhile, there is a significant negative correlation between SST and SKJ CPUE in the tropical regions of the western and central Indian Ocean. Our results suggest that climate oscillations have a 0–2 year lag effect on the SKJ fishery in the Indian Ocean, which can be used to predict resource changes in SKJ over the next 2 years.

Influence of Temperature on the Removal Efficiency of Organic Matter and Ammonia from Micro-Polluted Source Water

Temperature is an important factor influencing the treatment effect of biological aerated filters (BAFs). In this study, BAFs incorporating biological manganese oxides (BMOs) were used to treat micro-polluted source water containing organic masses and ammonia, and the influence of temperature on the removal efficiency of the pollutants was investigated. The results showed that after the formation of biogenic manganese oxides (BMOs) in the filter layer, the removal efficiency of CODMn significantly improved. When the water temperature was approximately 24 °C, 16 °C, and 6~8 °C, the removal rates of CODMn, ammonia, and manganese were 60.64, 42.55, and 20.48; 98.40, 95.58, and 85.04; and 98.70, 97.63, and 96.38%, respectively. The influence of water temperature on the removal efficiency of the pollutants was hierarchically structured as follows: CODMn &gt; ammonia &gt; manganese. Analysis of the removal efficiencies of the pollutants along the filter layer showed that CODMn had been eliminated in every filtration layer, and ammonia and manganese were mainly removed in the 0~0.4 m and 0~0.8 m regions of the filter layer, respectively. With a decreasing water temperature, the concentrations of CODMn, ammonia, and manganese along the filter layer increased. The biological CODMn, manganese, and ammonia removal processes were all first-order kinetic reactions. With a decreasing water temperature, the kinetic constant k gradually decreased, and the reaction half-life (t1/2) gradually increased.

An Enhanced Measurement for Inorganics in Water Based on a Novel Planar Three-Electrode Sensor

Although conductivity is prevalently used in water quality detection for inorganic ions, its utility could be weakened when various kinds of ions are involved as it merely embodies water bulk resistance indiscriminately. Aiming at detectability enhancement, the paper proposes a novel measurement method utilizing interfacial impedance for further exploration of ions. Based on theoretical analysis and measuring model comparison, a current-controlled method with difference measurement was derived, as well as the equivalent circuit. Then, a novel three-electrode sensor with planar structure was accordingly designed and fabricated. After measurement parameters optimizing by experiments of frequency response and amplitude response, the sensor was tested with traditional two-electrode sensor and conductivity sensor. Experimental results not only testified performance of the proposed one in interfacial impedance measurement, but also revealed a reduction process of interfacial impedance with increasing conductivity. Influence of water temperature was tested, too. Impedance differences between anion and cation inspired further experiments involving more ion species, which demonstrated that diverse positive ions trended to have similar relationships between conductivity and interfacial impedance while the relationships differed due to types of negative ions. The relationships make the measurement a promising tool for ion detection in certain applications.

An assessment of the economic feasibility of the floating PV technology in Aotearoa–New Zealand

Electricity generation from utility-scale solar facilities is projected to grow to between 5 and 16 TWh by 2050 in Aotearoa–New Zealand. The floating photovoltaic (FPV) technology is considered a viable option for the country, because of the good solar resource at existing hydropower schemes. This paper aims to inform the understanding of the economic feasibility of FPV systems through the analysis of specific cases – Maraetai Dam and Lake Tekapo. To do so, the solar resource and FPV outputs are obtained through the modelling of Solargis and using industry standard technical specification. As well as the normal uncertainties associated with (potential) FPV performance evaluations, the influence of water temperature is also considered. The overall FPV output is estimated to be between 1,115 and 1,497 kWh/kWp. Using available Engineering, Procurement and Construction (EPC) costs, the levelized cost of energy (LCOE) metric, for a 10 MW installation, is determined to be between NZ$176 and NZ$237 per MWh, with total electricity generation over 25 years between 263 and 353 GWh. In order to reach the required LCOE value of less than NZ$100/MWh for utility scale generation, the EPC costs will have to be reduced by a factor of 2 to around NZ$1,500/kWp.