Un-ionized Ammonia Research Articles

Salinity mediates the damage caused by acute and chronic ammonia stress in largemouth bass (Micropterus salmoides)

Ammonia is a critical pollutant in aquatic environments, posing significant risks to aquaculture by accumulating in culture systems due to fish excretion and organic matter decomposition. This study investigated the effects of ammonia toxicity on juvenile largemouth bass (Micropterus salmoides) under varying salinity conditions (0 and 5 psu), focusing on physiological responses and gut microbiota changes. Results indicated that ammonia exposure led to increased mortality, oxidative stress, liver damage, and significant shifts in gut microbial communities, especially under freshwater conditions. Elevated salinity mitigated these effects by reducing the bioavailability of toxic un-ionized ammonia (UIA) and enhancing the fish's physiological resilience, particularly in the kidney and intestine. Ammonia exposure significantly increased the IBR index values in all three organs, with the gills showing the most pronounced stress response, followed by the kidney and intestine. Salinity had a significant mitigating effect by reducing the oxidative stress response in comparison to freshwater conditions. However, in the gills, the protective effect of salinity was not enough to fully counteract the oxidative stress induced by ammonia. Ammonia exposure in freshwater favored pathogenic gut bacteria genera such as Aeromonas, while higher salinity enriched stress-resistant genera like Ralstonia and Klebsiella. These findings contribute to a better understanding of the interaction between salinity and ammonia toxicity, suggesting that moderate salinity increases within the fish's tolerance range could be an effective strategy in aquaculture to reduce ammonia toxicity and promote fish health.

Carbon Nanotube-Based Chemiresistive Sensor Array for Dissolved Gases.

Dissolved gases such as oxygen (DO) and ammonia (dNH3) are among the most consequential parameters for the assessment of water quality. Since the concentrations of DO and dNH3 are interdependent through the nitrogen cycle, simultaneous monitoring can be useful in many applications. For example, in wastewater treatment, aeration baths are used to adjust the rate of removal of ammonia by the bioactive sludge. Here, we have developed a sensing array which can monitor dissolved molecular oxygen (DO) and dissolved un-ionized ammonia (dNH3) continuously and simultaneously. This was achieved by functionalizing two sensors made from single-walled carbon nanotube (SWCNT) films with two different molecules: phenyl-capped aniline tetramer (PCAT) and iron phthalocyanine (II) (FePc). It was found that the FePc-doped SWCNT (FePc@SWCNT) sensors demonstrated good sensitivity and selectivity to DO, compared to dNH3. Conversely, we found that the PCAT-doped SWCNT (PCAT@SWCNT) sensors demonstrate greater sensitivity to ammonia. Investigating the effect of different PCAT salts as a dopant, we describe the following series of sensor responses to ammonia: chloride < crotonate < fumarate. Additionally, we coated our sensors with thin PDMS membranes, which are selectively permeable to gases, over ionic species. Finally, using principal component analysis (PCA) and partial least-squares discriminant analysis, it was possible to discriminate between responses to DO and dNH3, with 100% accuracy. As a result, here, we have developed a compelling proof-of-concept for the use of a single sensing substrate, doped with molecules with distinct mechanisms of interaction with two different analytes, to simultaneously monitor concentrations of two dissolved gases, in this example, DO and dNH3.

Correlation and regression analysis of unionised ammonia ions, NH3and pH in ornamental fish aquatic environment

Assessing ammonia in water is very important for fish farmers as it is one of the pollutants that may affect the water quality. In water, ammonia can be found either in the form of unionised ammonia NH3 or ionised ammonia NH+4, which contribute to a total ammonia nitrogen (TAN). In assessing the ammonia toxicity, NH3 provides a more accurate measure of toxicity and needs to be monitored consistently, rather than relying solely on TAN. However, the method of measuring NH3 in water can be complex and challenging. Therefore, the ability to determine the correlation between NH3 and other parameter which is easier to be measured (such as pH) is crucial to enable the estimation of NH3. This study was conducted to determine the correlation between NH3 and pH based on the data collected from Redgold Aquatics ornamental fishponds located in Sik, Kedah. The pH was assessed by a commercial measuring device, while the NH3 was calculated using an appropriate mathematical equation that requires the data of pH, TAN, and temperature. The correlation and regression analysis were conducted via the IBM SPSS tool and Microsoft Excel. The result shows that NH3 and pH are highly correlated with regression equation of NH3 = 0.01pH – 0.07. In addition, factors that may affect the total ammonia value have been discussed thoroughly in this work. The analysis of these water quality parameters may assist farmers in estimating the toxic ammonia, NH3 from the known water pH.

Photocatalytic treatment of diverse contaminants of potential concern in oil sands process-affected water

Oil sands process-affected water (OSPW), generated by surface mining in Canada's oil sands, require treatment of environmentally persistent dissolved organic compounds before release to the watershed. Conventional chemical and mechanical treatments have not proved suitable for treating the large quantities of stored OSPW, and the biological recalcitrance of some dissolved organics may not be adequately addressed by conventional passive treatment systems. Previous work has evaluated photocatalytic treatment as a passive advanced oxidation process (P-AOP) for OSPW remediation. This work expands upon this prior research to further characterize the effects of water chemistry on the treatment rate and detoxification threshold. Under artificial sunlight, buoyant photocatalysts (BPCs) detoxified all OSPW samples within 1 week of treatment time with simultaneous treatment of polycyclic aromatic hydrocarbons, naphthenic acid fraction components (NAFCs), and un-ionized ammonia. Overall, these results further demonstrate passive photocatalysis as an effective method for treatment of OSPW contaminants of potential concern (COPCs).

Modeling embryo survival: Genetic and environmental influences on eye-up rate in a north American Atlantic salmon selective breeding program

Selective breeding programs improve target traits but can also unintentionally change genetically correlated traits in the selected strain. The U.S. Department of Agriculture–Agricultural Research Service National Cold Water Marine Aquaculture Center (NCWMAC) in Franklin, Maine maintains a North American Atlantic salmon selective breeding program focused on improving commercially important traits (e.g., carcass weight). However, the program has experienced a significant decline in the percent of eyed embryos over its 14 years of operation, leading to concerns that reproductive performance was being unintentionally changed by selection for the target traits. The aims of this study were to 1) model eye up success as a potentially heritable trait utilizing the recorded pedigree and 2) assess the relationship between eye-up rate and environmental conditions experienced by the broodstock. Over 14 years of data encompassing 1537 full-sib families produced by 1537 dams and 885 sires was analyzed. Counts of eyed embryos and carcass weight were analyzed with a linear multi-trait trait model that included maternal genetic effects and a spawn year effect to determine the strength of genetic and environmental influences on the eyed embryo rate. To investigate the environmental influences in more detail, we assessed the correlation between water quality parameters in the broodstock rearing system observed over the same 14-year time period and the estimated spawn year effects. There was small heritability of the direct genetic effect (0.059 ± 0.009) and the maternal genetic effect (0.039 ± 0.013). Comparatively, the proportion of phenotypic variance explained by the maternal environmental effect was moderate (0.165 ± 0.012). The genetic correlations between carcass weight and eye up rate were very small and had a large amount of uncertainty. The correlation between the direct genetic effects on eye-up and carcass weight was −0.0528 ± 0.1469 while the correlation between the maternal genetic effect on eye-up and the direct genetic effect on carcass weight was 0.2030 ± 0.1791. The correlation between maternal common environmental effects on the two traits was also low at 0.0676 ± −0.0804. The effect of spawn year was statistically significant (p < 0.01), and the values were negatively correlated with mean un-ionized ammonia (mg/L, −0.56, p = 0.04,), nitrate concentrations (mg/L r = −0.65, p = 0.01) and temperature (°C, r = −0.61, p = 0.02) experienced by the broodstock prior to spawning. Overall, the results suggest that the decrease in eyed embryos over time was not caused by inadvertent selection but instead due to increases in water temperature and/or nitrogenous waste concentrations in the broodstock rearing system. Further investigation of the mechanisms behind these apparent environmentally induced declines and potential mitigation measures to prevent decreases in eye-up rates are needed.

Implications of ammonia stress for the pathogenicity of Shewanella spp. in Oreochromis niloticus: effects on hematological, biochemical, immunological, and histopathological parameters

Environmental stressors (such as ammonia) in aquaculture could increase the risk of pathogenicity, posing a more severe threat to farmed fish. The aim of this study was to investigate the effects of ammonia stress on the pathogenicity of Shewanella spp. in Oreochromis niloticus. First, a 96-hour static test was used to determine the median lethal concentration (LC50) of unionized ammonia to Nile tilapia. After 96 h of exposure, the Un-ionized ammonia (UIA) LC50 was estimated to be 4.26 mg/L. Second, an experiment was conducted to test the effect of unionized ammonia stress on the pathogenicity of Shewanella spp. in O. niloticus for 30 days. A study involved 180 fish divided into six groups, with the first group serving as a control. The second group (AMN1/10) and the third group (AMN1/20) were not challenged and were exposed to 1/10 (0.42 mg/L) and 1/20 (0.21 mg/L) of the 96-hour LC50 of UIA, respectively. Then 0.2 mL (0.14 × 105) of Shewanella spp. was intraperitoneally injected into the fourth (SH), fifth (SH + AMN1/10), and sixth (SH + AMN1/20) groups, which were subjected to 0, 1/10 (0.42 mg/L), and 1/20 (0.21 mg/L) of the 96-hour LC50 of UIA, respectively. The survival rate, hematological indices, immunological parameters, and antioxidant activity of the fish significantly decreased when they were exposed to ammonia and Shewanella infection separately or together. Histopathological changes were also observed in the kidney and liver. Furthermore, both individual and combined exposures significantly altered renal and hepatic function, with notable increases in glucose and cortisol levels, as well as in the expression of proinflammatory cytokine genes (TNF-α and IL-1ß). However, the detrimental effects of co-exposure to ammonia stress and Shewanella infection were greater than those of separate exposures. As a result, we may say that increased ammonia concentrations enhance the infection of Shewanella spp. These findings could contribute to a better understanding of Shewanella infection in Nile tilapia.

Overview on the role of dietary Spirulina platensis on immune responses against Edwardsiellosis among Oreochromis niloticus fish farms

Edwardsiellosis is a bacterial fish disease that mostly occurs in freshwater farms and is characterized by a high mortality rate. Edwardsiella tarda strain was recovered from 17 fish out of 50 Nile tilapia, which were harboring clinical signs of systemic septicemia. The level of un-ionized ammonia (NH3) in the fish farm’s water was 0.11–0.15 mg/L, which was stressful for the Nile tilapia.Sequencing of the gyrB1 gene confirmed that the isolate was E. tarda JALO4, and it was submitted to NCBI under the accession number PP449014. The isolated E. tarda harbored the virulence gene edw1 AHL-synthase (quorum sensing). In addition, the isolate was sensitive to trimethoprim and sulfamethoxazole mean while it was intermediate to florfenicol. The median lethal dose (LD50) of E. tarda JALO4 was determined to be 1.7 × 105 CFU/mL in Nile tilapia.In the indoor experiment, Nile tilapia (45.05 ± 0.4 g), which received dietary Spirulina platensis (5 and 10 g/kg fish feed), showed optimum growth and feed utilization. Meanwhile, after receiving dietary S. platensis, the fish’s feed conversion ratio (FCR) was significantly enhanced compared to the control, which was 1.94, 1.99, and 2.88, respectively. The expression of immune-related genes interleukin (IL)-1β and tumor necrosis factor (TNF)-α were upsurged in E. tarda-challenged fish with higher intensity in S. platensis groups. Dietary S. platensis at a dose of 10 g/kg fish feed could provide a relative protection level (RPL) of 22.2% Nile tilapia challenged against E. tarda. Nile tilapia experimentally infected E. tarda, drastically altering their behavior: higher operculum movement, low food apprehension, and abnormal swimming dietary S. platensis (10 g/kg fish feed) could rapidly restore normal status.It was concluded that Edwardsiellosis could alter Nile tilapia behavior with a high loss in fish population. Fish received dietary-S. platensis could rapidly restore normal behavior after E. tarda infection. It is recommended the incorporation of S. platensis at doses of 10 g/kg into the Nile tilapia diet to boost their immunity and counteract E. tarda infection.

Response and recovery of nitrifying moving bed biofilm reactor systems exposed to 1°C with varying levels of ammonia starvation

This study investigated the impact of varying total ammonia nitrogen (TAN) feed levels along with water temperature decreases on the performance of nitrifying moving bed biofilm reactor (MBBR) at 1 °C and its recovery at 3 °C. Five MBBR reactors were operated with different TAN concentrations as water temperature decreased from 20 to 3 °C: reactor R1 at 30 mg N/L, reactor R2 at 20 mg N/L, reactor R3 at 15 mg N/L, reactor R4 at 10 mg N/L and reactor R5 at 0 mg N/L. The corresponding biofilm characteristics were also analyzed to understand further nitrifying MBBR under different TAN feeding scenarios. The findings revealed that the higher TAN levels were before reaching 1 °C, the better nitrification performance and the more biomass grew. However, the highest TAN concentration (30 mg N/L) might negatively affect the nitrification performance, the activity of nitrifiers, and the growth of biofilms at 1 °C because of the toxic effects of un-ionized or free ammonia (FA). It was observed that the activities of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were affected by FA concentrations ranging from 0.2 to 0.7 mg N/L at 1 °C, but they could gradually be adapted to such inhibitory environment, with NOB recovering more quickly and robustly than AOB. The study identified 20 mg N/L (67 % of maximum influent TAN at 1 °C in R2 as the optimal TAN feeding concentration, achieving over 90 % TAN removal and a surface area removal rate (SARR) of 0.78 ± 0.02 g N/m2·d at 1 °C. Meanwhile, R2 also exhibited the highest biofilm mass, with total solids at 13.3 mg/carrier and volatile solids at 11.3 mg/carrier. As TAN was removed, nitrite accumulation was observed at 1 °C, and higher influent TAN concentrations prior to 1 °C appeared to delay the accumulation. When water temperature increased from 1 °C to 3 °C, nitrification performance improved significantly in all reactors without nitrite accumulation, and the higher TAN feeding in the previous stage led to faster recovery. Compared with 20 °C, biofilm became thinner and denser at 1 °C and 3 °C. Furthermore, this study revealed significant shifts in microbial community composition and nitrifier abundances in response to changes in water temperature and influent TAN levels. The dominant nitrifiers were identified as Nitrosomonadaceae (AOB) and Nitrospiraceae (NOB). At 1 °C, the nitrifier abundances were significantly correlated with SARRs, FA, and biofilm density. R2, which exhibited the best nitrification performance, maintained higher nitrifier abundances at 1 °C.

The Ability of the Red Tilapia (Oreochromis sp.) to Tolerate Different Concentrations of Unionized Ammonia and Water Salinity Levels

The Ability of the Red Tilapia (Oreochromis sp.) to Tolerate Different Concentrations of Unionized Ammonia and Water Salinity Levels

Nile tilapia (Oreochromis niloticus) show high tolerance to acute ammonia exposure but lose metabolic scope during prolonged exposure at low concentration

Ammonia is a respiratory gas that is produced during the process of protein deamination. In the unionised form (NH3), it readily crosses biological membranes and is highly toxic to fish. In the present study we examined the effects of unionized ammonia (UIA), on the resting oxygen consumption (MO2), ventilation frequency (fV), heart rate (HR) and heart rate variability (HRV) in Nile tilapia (Oreochromis niloticus). Fish were either exposed to progressively increasing UIA concentrations, up to 97 µM over a 5 h period, or to a constant UIA level of 7 µM over a 24 h period. For both treatment groups resting MO2, HR and fV were recorded as physiological variables. Relative to the control group, the fish groups exposed to the incremental UIA levels did not exhibit significant changes in their MO2, HR and fV at UIA concentrations of 4, 10, 35, or 61 µM compared to control fish. Exposure to 97 µM UIA, however, elicited abrupt and significant downregulations (p < 0.05) in all three responses, as MO2, HR and fv decreased by 25, 54 and 76 % respectively, compared to control measurements. Heart rate became increasingly irregular with increasing UIA concentrations, and heart rate variability was significantly increased at 61 and 97 µM UIA. Prolonged exposure elicited significant changes at exposure 7 µM UIA. Standard (SMR) and maximum metabolic rate (MMR) were significantly reduced, as was the corresponding fV and HR. It is evident from this study that Nile tilapia is tolerant to short term exposure to UIA up to 61 µM but experience a significant metabolic change under conditions of prolonged UIA exposures even at low concentrations.

Growth performance, hematological profile, and related genes expression in goldfish (Carassius auratus) fed on rosmarinic acid-enriched diets and subjected to ambient ammonia

Recently, supplementing fish diets with polyphenols has attracted more attention because of their great nutritional role. The unionized ammonia is one of the critical water parameters that adversely affects the fish performance and welfare status. Hence, the present perspective outlines the potential value of dietary rosmarinic acid (RA) in boosting growth, hematological, and immune biomarkers, besides related-genes expressions post-exposure of goldfish (Carassius auratus) to ambient ammonia. Fish (n = 240) were separated into four groups; RA0 (the control), RA400, RA600, and RA800 received 0, 400, 600, and 800 mg RA/kg feed, respectively. After 56 days, counts of white and red blood cells and growth indices (weight gain, specific growth rate, feed intake, and feed conversion ratio) were evaluated. After that, the fish per each treatment were exposed to 0.5 mg/L of unionized ammonia for three hours. After the challenging time, many biomarkers were measured including immune response (ACH50, total immunoglobulin, and lysozymes activity), digestion (proteases activity), and genes expression involving MUC, HSP27, HSP30, HSP47, TNFa, Lp1, and Fas genes plus the anti-inflammatory cytokines (IL6, IL8, and IL10). The findings of the current research revealed that dietary RA intervention fostered growth performance, improved blood picture (p < 0.05), and enhanced (p < 0.05) the expression of genes, which are responsible for modulating immunity and anti-inflammatory status in a dose-dependent manner. The present study concluded that dietary RA is a successful natural feed supplement for goldfish with an optimal level of 600 mg RA/kg feed. However, it verifies antitoxic and anti-inflammatory properties against ambient ammonia toxicity. It also has a promising influence on the growth, hematological, and immunity and anti-inflammatory related genes expression of goldfish, C. auratus.

Ammonia distribution and ecological risk assessment in nine fresh lakes in China.

With the development of industry and economy, ammonia nitrogen pollutions in surface water are of great concern worldwide. This study investigated the historical contents of total ammonia nitrogen (TAN) and unionized ammonia molecules (NH3) in nine fresh lakes in China during 2014-2022. Three different classification methods (flood season, season, and geographical distribution) were used to analyze the concentration variation of TAN and NH3. The concentration of TAN first decreased and then increased in the flood season, showing a lower concentration in summer and a higher concentration in winter. The variation trend of NH3 was in an opposite way with TAN. Correlation analysis between ammonia and 10 water quality parameters and 4 pollution emission and treatment parameters showed that the correlation coefficient between TAN and total phosphorus (total nitrogen) was 0.44 (0.43), respectively. The correlation coefficients between average annual TAN concentration and total emissions (waste water treatment input) were 0.35 (0.53), respectively. Combined with ecotoxicity data from a series of aquatic species, the ecological risks of TAN and NH3 in lakes were evaluated using hazard quotient and joint probability curve methods. From 2014 to 2022, the probability of 5% species affected in the acute ecological risk of TAN and NH3 is lower than 0.01, but for the chronic ecological risk of TAN and NH3, the probabilities of 5% species affected are 0.003-0.030 and 0.04-0.14, respectively. The chronic ecological risks were higher than the acute ecological risks, and high risks in plateau lakes like Dianchi Lake should be paid more attention to.

Effectiveness and safety of clove oil and common salt in the long-term transport of Cyprinus carpio

In this study, we aimed to evaluate the effectiveness and safety of clove essential oil (CEO) in combination with common salt during the long-term transport (24 h) of Cyprinus carpio. The experiment was conducted according to a completely randomized design with a 4 × 2 factorial arrangement, including four levels of CEO (0, 5, 10, and 15 mg L−1) and two levels of common salt (0 and 3 g L−1). Sampling was carried out before, immediately after, and 96 h after transport. CEO alone was not completely safe for C. carpio during transportation, as indicated by the increase in unionized ammonia in water and oxidative stress in fish gills and liver. Although common salt reduced water ammonia and fish stress responses (blood glucose), its use in isolation is not recommended, as it caused oxidative damage to the liver and gills. These effects had not been previously reported in the literature. However, the use of 5 mg L−1 CEO in combination with salt provided the best results both immediately after and 96 h after transport. In gills, there was a reduction in nitric oxide and carbonylated proteins and an increase in catalase activity at 96 h after transport. In the liver, there was a decrease in nitric oxide and oxidative damage (carbonylated proteins and malondialdehyde) immediately after transport, as well as a decrease in nitric oxide and an increase in glutathione-S-transferase activity at 96 h after transport. Thus, combined use of 5 mg L−1 CEO and 3 g L−1 common salt proved to be effective and safe, resulting in better maintenance of water quality (lower ammonia content) and redox status of the gills and liver in C. carpio during long-term transport.

A novel photo-assisted activated persulfate strategy for selective oxidation of ammonia nitrogen to dinitrogen using sodium silicate and sodium sulfite as regulators

Persulfate (PS)-based advanced oxidation processes (SR-AOPs) is a promising approach for the removal of ammonia nitrogen (NH3-N) from wastewater, but it suffered from the low removal efficiency and the excessive oxidation of NH3-N to nitrate (NO3−) or nitrite (NO2−) in the absence of in-situ generated chlorine radicals. Therefore, it is still a challenge to improve the efficiency of NH3-N removal and the selectivity of NH3-N oxidation products towards dinitrogen (N2) by SR-AOPs without chlorine radicals. Herein, a novel photo-assisted activation of SR-AOPs involving sodium silicate (Na2SiO3) and sodium sulfite (Na2SO3) was developed for NH3-N removal from wastewater. In this system, Na2SiO3 was acted as a green buffer to maintain NH3-N in the form of un-ionized ammonia (NH3) with strong reducibility, promoting the efficiency of NH3-N removal as well as ensuring the neutral effluent by receiving the H+ from PS activation. Na2SO3 could inhibit the excessive oxidation of NH3-N by regulating the redox potential of the solution and generating hydrated electrons (eaq−) under light (hv) irradiation, enhancing the selectivity of NH3-N oxidation products towards N2. 100 % of NH3-N removal efficiency and more than 98 % of N2 selectivity were obtained after 30 min at the initial pH of 3–9 and the initial NH3-N concentration of 30 mg N/L. Based on the quenching experiment, EPR test and probe experiment, the HO and SO4− were the main reactive oxygen species (ROS) to be responsible for NH3-N oxidation. This study proposed a new approach for treatment of wastewater containing NH3-N by SR-AOPs.

Locomotory behaviour of euryhaline rotifer Brachionus rotundiformis: The potential influence of probiotics on swimming pattern and speed

AbstractWe evaluated the effect of probiotics on the growth and culture condition of rotifer in medium‐sized culture tanks. The influence of probiotics on the changes in swimming patterns, velocity and sinuosity indices of rotifer was also examined. The rotifers (Brachionus rotundiformis) were cultured for 14 days in nine polycarbonate tanks containing seawater which were divided into three groups: a control group (Chlorella product) and two treatment groups: Chlorella + Probiotic I and Chlorella + Probiotic II. The rotifer population and the water quality parameters were monitored daily. To evaluate the locomotory behaviour of the rotifer, a sub‐sample containing rotifers was obtained from each treatment and placed on a glass‐bottomed dish. A high‐speed camera mounted on a stereo microscope was used to record the rotifer movement. The footage was then analysed using motion analysis software to establish the swimming velocity, swimming pattern and sinuosity indices of the rotifers. Co‐feeding rotifer on microalgae and probiotics resulted in a higher rotifer growth rate (0.51 ± 0.03) and decreased concentration of unionized ammonia (0.14 ± 0.02 mg L−1). In addition, the probiotic‐fed rotifers had 1.59 times higher average swimming velocity (0.97 ± 0.11 mm s−1) and more straight swimming pattern compared to rotifers that fed on microalgae alone whose velocity was slow (0.61 ± 0.14 mm s−1) and more sinuous. From these data, we can postulate that probiotics have the potential to attenuate rotifer culture conditions by decreasing ammonia concentration as well as influence rotifer swimming behaviour which could affect rotifer reproduction and the quality of fish larvae in aquaculture systems.

Model-based versus model-free feeding control and water-quality monitoring for fish-growth tracking in aquaculture systems

This paper proposes model-based and model-free control approaches to monitor the feeding rate and water quality for fish-growth tracking in aquaculture systems. The representative fish-growth model is revisited, which describes the total biomass change by incorporating the fish population density and mortality. Due to the challenging task of measuring the total fish biomass and population data, the new dynamic population model is validated with individual fish-growth data for tracking control. Ammonia exposure is a significant challenge in the fish-population growth tracking problem, affecting fish health and survival. To address this challenge, traditional and optimal controllers are first designed to track the weight reference within suboptimal temperature and dissolved oxygen (DO) profiles under various un-ionized ammonia (UIA) exposure levels by manipulating relative feeding. Then, a Q-learning approach is proposed to learn an optimal feeding-control policy from simulated data on fish-growth weight trajectories while managing ammonia effects. The proposed Q-learning feeding control prevents fish mortality and achieves good tracking errors for fish weight under UIA levels. However, it maintains a relative food consumption that potentially underfeeds fish. Finally, an optimal predictive algorithm that includes the temperature, DO, and UIA is proposed to optimize the feeding and water quality of the dynamic fish-population growth process, indicating that fish mortality is decreased and food consumption is reduced in all cases of UIA exposure.

Impacts of long-time transportation on whiteleg shrimp (Penaeus vannamei) muscle quality and underlying biochemical mechanisms.

Shrimp is widely consumed around the world. Since muscle is the primary edible component of shrimp, muscle quality (particularly texture) has a direct impact on the economic value of shrimp products. However, reports on the shrimp muscle quality influenced by transportation are rather limited, and the underlying mechanism remains unknown. During the simulated transportation, the water pH and total ammonia-nitrogen content and un-ionized ammonia contents were elevated. Furthermore, reductions in shrimp muscle water-holding capacity, hardness, and shear value with intensive myofibrillar protein degradation were detected. Simulated transportation decreased the pH and glycogen content of shrimp muscle while increasing lactic dehydrogenase activity and lactate content, resulting in an elevated level of free calcium ions and increased μ-calpain and general proteolytic activities. Water exchange could improve the water quality and reduce the mortality of shrimp during transportation, as well as decrease muscle textural softening by alleviating these stress responses. Maintaining water quality and, in particular, reducing ammonia are critical to improving shrimp survival and muscle quality during live transportation. This study is of great significance for the better maintenance of the textural properties of shrimp meat. © 2023 Society of Chemical Industry.

The mediatory role of water quality on the association between extreme precipitation events and infectious diarrhea in the Yangtze River Basin, China

Extreme precipitation is exacerbating the burden of infectious diarrhea in the context of climate change, it is necessary to identify the critical and easy-to-intervene intermediate factors for public health strategies. Water quality may be the most important mediator, while relevant empirical evidence is limited. This study aimed to examine the role of water quality in the process of infectious diarrhea caused by extreme precipitation. Weekly infectious diarrhea cases, meteorological factors and water quality data in Yangtze River Basin in China between October 29, 2007 to February 19, 2017 were obtained. Two-stage statistical models were used to estimate city-specific extreme precipitation, water quality and infectious diarrhea relationships that were pooled to derive regional estimates. A causal mediation analysis was used to assess the mediation effect of water quality. In Yangtze River Basin, extreme precipitation events had a significant impact on infectious diarrhea (Incidence Rate Ratios [IRR]: 1.027, 95% Confidence Interval [CI]: 1.013∼1.041). After extreme precipitation events, the dissolved oxygen (DO) in surface water decreased (-0.123 mg/L, 95%CI: -0.159 mg/L∼-0.086 mg/L), while the un-ionized ammonia (NH(3)-N) increased (0.004 mg/L, 95%CI: 0.001 mg/L∼0.006 mg/L). The combined overall effect of DO and NH(3)-N on infectious diarrhea showed that both low and high concentrations were associated with an increased risk of infectious diarrhea. The causal mediation analysis showed that the mediation proportion of the two water quality indexes (DO and NH(3)-N) is 70.54% (P < 0.001). To reduce the health effects of extreme precipitation, in contrast to current population-oriented health strategies, those that take into account more direct and easy-to-intervene water quality indicators should be encouraged by future policies.

The effects of Bacillus species probiotics (Bacillus subtilis and B. licheniformis) on the water quality, immune responses, and resistance of whiteleg shrimp (Litopenaeus vannamei) against Fusarium solani infection

This study investigated the impacts of water application of a commercial Bacillus species probiotics, SANOLIFE®PRO-W (containing Bacillus subtilis and B. licheniformis), on water quality, digestive enzymes, growth performance, antioxidants, innate immunity, body composition, and resistance of whiteleg shrimp against Fusarium solani infection. A total of 240 animals (2.00 ± 0.07 g) were stocked into twelve 1-m3 concrete ponds and divided into four triplicate treatments. For 56 days, the rearing water was supplemented with Bacillus species probiotic at 0, 0.01, 0.02, and 0.03 g/m3 and defined as control, T1, T2, and T3 groups, respectively. Results revealed that Bacillus species probiotics increased dissolved oxygen and decreased total ammonia, nitrite, and unionized ammonia in the rearing ponds. However, adding probiotic Bacillus to rearing water significantly increased the digestive enzyme (chymotrypsin, trypsin, protease, lipase, and amylase) and growth performance parameters compared to the control. On the other hand, the antioxidant levels of superoxide dismutase, catalase, and glutathione peroxidase were increased significantly, while the malondialdehyde concentrations were decreased significantly compared to the control. Furthermore, Bacillus probiotics boosted the innate immunity of shrimp manifested by increased activities of lysozyme, prophenoloxidase, respiratory burst, and the total hemocyte count compared with the control treatment. Of interest, shrimp mortalities decreased after F. solani infection to 35% in the T3 group compared to 100% in the control group. In conclusion, water application of Bacillus species probiotics, especially at 0.02 and 0.03 g/m3, improved the water quality, welfare, and resistance of whiteleg shrimp to F. solani infection.

Dietary effects of Sanacore® GM on productive performance, immune-antioxidative status, cytokines, and resistance of European sea bass to Vibrio alginolyticus infection

ABSTRACT This study examined the dietary effects of Sanacore®GM (SAN) on growth and production, immune-antioxidative status, cytokines, and the resistance of European sea bass to Vibrio alginolyticus infection. Fish (28.5–32.3 g) were fed on 0.0, 1.0, 2.0, 4.0, 6.0, and 8.0 g SAN/kg feed for ten weeks. Following that, fish were intraperitoneally injected with V. alginolyticus, and observed for further ten days. Among different water quality parameters, only unionized ammonia and nitrite values were significantly declined in groups received 4.0–8.0 g SAN/kg feed. Significant increases in fish growth, production, hematological, and immune-antioxidant indices were observed in SAN-fed fish. Compared with the control group, IL-1β and TNF-α genes expressions were down-regulated in groups fed on 4.0–8.0 g SAN/kg feed. After bacterial infection, low fish mortalities (20%–10%) were observed in fish fed with 4.0–8.0 g SAN/feed, respectively. The polynomial fitting curve demonstrates that the optimum SAN level for European sea bass is 5.0 g/kg feed.