Un-ionized Ammonia Research Articles

Detecting the effect of water level fluctuations on water quality impacting endangered fish in a shallow, hypereutrophic lake using long-term monitoring data

Water level fluctuations (WLFs) affect phytoplankton dynamics, water quality, and fish populations in lakes and reservoirs around the world. However, such effects are system-specific and vary due to interactions with other external factors such as solar radiation, air temperature, wind, and external phosphorus loading. Utilizing data from a long-term monitoring program (1990–2016), we developed an approach using cross-tabulation contour and conditional probability analyses to detect the effects of WLFs on the frequency of poor water quality impacting native fish in a large, shallow, hypereutrophic lake. Through the incorporation of long-term inter-annual and seasonal variability in climatic factors and cyanobacterial bloom periodicity, our approach detected non-linear WLF effects whereby both high and low-lake levels were associated with higher probabilities of poor water quality conditions stressful to fish including high pH, high un-ionized ammonia, and low dissolved oxygen. Although lake level management may not prevent poor water quality in any given year due to other external factors such as temperature or wind, we determined that seasonally based intermediate lake levels bracketing the long-term median afforded the best water quality conditions for endangered fish during the summer period when poor water quality is most common.

Natural co‐infection of cultured Nile tilapiaOreochromis niloticuswithAeromonas hydrophilaandGyrodactylus cichlidarumexperiencing high mortality during summer

Aeromonas hydrophila and Gyrodactylus cichlidarum are common pathogens that induce significant economic losses in farm-reared Nile tilapia. Nowadays, the sudden appearance of fish mortalities was exaggerated due to mixed and multiple infections. During summer 2016, mass mortality among earthen pond-farmed Nile tilapia was reported. Clinico-pathological, bacteriological and parasitological examinations have been demonstrated. As well, the water quality parameters were assessed. The clinical and histopathological findings of the moribund and recently dead fish were characterized by generalized septicaemic signs. The water quality parameters were significantly elevated over the permissible levels, whereas there was an elevation in nitrite (0.04 mg/L), un-ionized ammonia (0.8 mg/L), hydrogen sulphide levels (153.1 mg/L) and organic matter content (3.79 mg/L). A. hydrophila was identified based on phenotypic characterization, API 20E features and the homology of 16S rRNA gene sequence analysis. In addition, PCR data confirmed the presence of aerolysin (aerA) and haemolysin (hly) genes in the identified A. hydrophila isolates. Gene sequencing and phylogenetic analysis based on 16S rRNA sequence confirmed that A. hydrophila H/A (accession No. MN726928) of the present study displayed 98%–99% identity with the 16S rRNA gene of A. hydrophila. Furthermore, the monogenetic trematode, G. cichlidarum was identified in the wet mounts from the skin and gills of the examined fish with a high infestation rate. In this context, it was reported that the synergistic co-infection of A. hydrophila and G. cichlidarum with deteriorated water quality parameters could induce exaggerated fish mortalities during hot weather.

Evaluating the Rearing condition of Rainbow Trout (Oncorhynchus Mykiss) Using Fuzzy Inference System

Rainbow trout (Oncorhynchus mykiss) is one of the most popular aquacultured species in the world. Sustainable production of this fish at commercial scale is very important but requires maintaining good water quality throughout the total rearing period. The present study aimed to develop a rainbow trout production index in order to raise awareness about the conditions of the rearing environment, enhance production, and reduce losses. For this purpose, an intensive rainbow trout production system was selected as the study system. In this system, there were seven stations including (a) 3000 5-g fish, (b) 3000 25-g fish, (c) 3000 50-g fish, (d) 3000 100-g fish, (e) 3000 220-g fish, (f) 2000 350-g fish, and (g) 2000 830-g fish. The fuzzy inference system was used to develop the target rearing index. Water quality parameters involved in the variation in the rainbow trout rearing conditions were classified into three groups including un-ionized ammonia, nitrite, and nitrate, Alkalinity and phosphate, along with dissolved oxygen and linear velocity. For each group and condition of rearing, a separate fuzzy inference system was defined and the output of each fuzzy system was named I1, I2, I3. Finally, I1, I2, and I3 were considered as the inputs to a fuzzy system in order to evaluate their effects on the index of general rearing conditions (I). The results indicated that un-ionized ammonia, nitrite, nitrate, and phosphate had negative effects while dissolved oxygen, linear velocity, and alkalinity positively affected water quality and rearing index. Most of the decline in the rainbow trout rearing index was related to the effect of un-ionized ammonia, nitrite, and nitrate due to food decomposition. Therefore, intelligence feeding based on fish appetite through reducing food conversion rate and water pollution can improve rainbow trout production in this system. The index of rainbow trout production conditions reflects the type, amount, and effect of water quality pollutants on rearing conditions. Producers can use this information to reduce the negative environmental effects and improve the product quality.

Acute toxicity of non-ionized ammonia on tambacu (Colossoma macropomum x Piaractus mesopotamicus)

Ammonia is a toxic compound to aquatic organisms and at high concentrations in water, it can cause various changes in the animal. Therefore, it becomes important to determine the tolerance of farmed aquatic animals for that substance. Thus, the aim of this study was to determine the mean lethal concentration (LC50-96 h) of un-ionized ammonia (NH3) in tambacu fingerlings (Colossoma macropomum x Piaractus mesopotamicus) in acute toxicity test. The fingerlings were exposed to ammonia at concentrations of: 0.09 (control); 0.54; 1.23; 2.52; 3.44 and 3.66 mg L-1 NH3, which were obtained from the application of NH4Cl. The test lasted 96 hours and mortalities were recorded over that period. The LC50 was determined by the Trimmed Spearman Karber statistical method. The LC50-96 h of non-ionized ammonia (NH3) for fingerlings of the tambacu hybrid was 1.63 mg L-1.

Acute and chronic toxicity of ammonia in Persian sturgeon, Acipenser persicus, fingerlings

In the present study, susceptibility of Persian sturgeon, Acipenser persicus, to un-ionized ammonia (UIA) was studied. Fish with an average weight of 5.52±0.45 g were exposed to different concentrations of un-ionized ammonia (UIA) to determine median lethal concentration (96-h-LC 50 ). The fish were exposed to six different concentrations of UIA (control, 0.16, 0.31, 0.62, 0.94 and 1.25 mg/l UIA). The control group was not challenged with ammonia (0.0008 mg/l UIA). The results showed that the 96-h-LC 50 of UIA in Persian sturgeon was 0.46 mg/l. According to 96-h-LC 50 ,mid-term exposure to sub-lethal UIA was examined. In the chronic examination, the fish were exposed to different levels of sub-lethal ammonia; control (0.0008 mg/l UIA), 10% of LC 50 (0.05 mg/l UIA), 5% of LC 50 (0.025 mg/l UIA) and 1% of LC 50 (0.005 mg/l UIA) for 30 days. Final length, final weight, weight gain, specific growth rate, daily weight gain and body weigh index decreased significantly in the fish exposed to 0.05 and 0.025 mg/l UIA. According to the results, conversion ratio and condition factor indices were higher in the fish exposed to 0.005 mg/l UIA and control group compared with the fish exposed to 0.05 and 0.025 mg/l UIA.

Assessment of water quality of best water management practices in lake adjacent to the high-latitude agricultural areas, China.

A major inland alkalinity lake in Northeast China, the Chagan Lake, was studied for the changes of its water qualities over the past three decades. Water quality data, including total nitrogen (TN), total phosphorus (TP), pH, dissolved oxygen (DO), and fluoride (F-), were analyzed to derive key indices for guiding water quality management. Our study found that the Chagan Lake had an average trophic state index (TSI) ranging 50 to 70; the average TSI for TP ranging between 70 and 80, and the average TSI for TN being 50. Over the past three decades, the TSI values generally trended lower, but there was a slight uptrend from 2012 onwards. Seasonal variations in the concentrations of TN and TP were identified. The TSI values in September were higher than those in May, while the values of un-ionized ammonia (UIA) during rainy seasons were higher than those during dry seasons. The average values of alkalinity and F- in the lake water exceeded the upper limits set in the Chinese water quality standards, i.e., 20 mg/L and 1 mg/L, respectively. It was defined that the evolution of lake water quality proceeded in four consecutive periods, namely natural, deterioration, improvement, and risk period; the improvement period benefitted from a historical water conservation project. Our study concluded that the amount of irrigation discharge into the Chagan must be monitored, and controlled, in order to sustain the critical ecological functions currently provided by the Chagan Lake.

Water quality criteria of total ammonia nitrogen (TAN) and un-ionized ammonia (NH3-N) and their ecological risk in the Liao River, China.

Ammonia has drawn great concern worldwide due to its ubiquity in surface water and high toxic effect. In China, ammonia pollution issues in the Liao River were highlighted from the Ministry of Ecology and Environment annual report. In this study, water quality criteria (WQC) for two types of ammonia (total ammonia nitrogen (TAN) and un-ionized ammonia (NH3-N)) and related temporal concentration distributions and ecological risks in the Liao River were investigated. For sampling sites (2014) and national monitoring sites (2008, 2013, 2016, 2017 and 2018) of the Liao River, there were seasonal variations identified for TAN and NH3-N. More specifically, high concentrations of TAN and NH3-N occurred separately in winter and summer, and there were increasing trends for TAN and NH3-N from 2013 to 2018. The acute and chronic WQC values for TAN based on the toxicity values of the Liao River species were 16.86 and 4.39 mg/L (pH of 7.0 and temperature of 20 °C), and the acute and chronic WQC values for NH3-N were 0.067 and 0.017 mg/L. The exceedance probabilities of 5% species affected for long-term exposure of TAN and NH3-N were ≥30% in 2014. In addition, the increasing trend of concentrations and ecological risks posed by NH3-N from 2013 should be paying more attention. This study could provide useful information for ammonia environmental risk management in China and ecological risk assessment procedure for NH3-N and TAN exposure in similar surface waters worldwide.

Alkaline water improves the growth and antioxidant responses of pacu juveniles (Piaractus mesopotamicus)

This study aimed to evaluate the effect of different water pH levels on the growth performance and oxidative stress responses of pacu juveniles. Pacu were subjected to four different water pH levels (5.5, 6.5, 7.5 and 8.5) for 45 days in recirculation aquaculture systems. The best growth performance occurred at a water pH of 8.5. At a water pH of 8.5, in general, alkalinity, nitrite and un-ionised ammonia were higher and plasma ions Na+ and K+ were lower than at other water pH values. Total ammonia was higher at a water pH of 5.5. Juveniles exposed to acidic water pH (5.5 or 6.5) showed a lower muscle antioxidant capacity against peroxyl radicals (ACAP) and glutathione S-transferase (GST) activity. Water pH did not affect survival, blood glucose and pH, haematocrit, plasma Cl−, and the muscle content of protein thiols (PSH) and thiobarbituric acid reactive substances (TBARS). In conclusion, a water pH of 8.5 is recommended for pacu production systems, since fish presented higher growth and antioxidant statuses at this pH.

Toxicological Assessment of Ammonia Exposure on Carassius auratus red var. Living in Landscape Waters.

To understand the toxic mechanism of ammonia and identify effective biomarkers on the oxidative stress for the fish Carassius auratus red var., acute and chronic toxicity tests were conducted. The 96-h LC50 of total ammonia nitrogen (TAN) for C. auratus was 135.4mgL-1, the corresponding unionized ammonia (NH3) concentration was 1.5mgL-1. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione-peroxidase (GSH-Px) and glutathione (GSH) showed an increase with a subsequent falling, while the malondialdehyde (MDA) increased during the chronic test. The SOD, MDA, and GSH could be effective biomarkers to evaluate the TAN oxidative stress, the maximum acceptable toxicant concentration (MATC) was 11.3mgL-1 for TAN. To our knowledge, this is the first study to propose biomarkers to evaluate potential environmental risk and establish a risk threshold for TAN in C. auratus.

Nitrification in a biofilm-enhanced highly loaded aerated lagoon.

A full-scale biofilm-enhanced aerated lagoon using fixed submerged media was monitored using automated water quality monitoring stations over the span of one year to quantify its nitrification performance. The system was operating at a high organic loading rate averaging 5.8gtotalCBOD5 /m2 of media per day (23.9gtotalCBOD5 /m3 of lagoon per day), a total ammonia nitrogen loading rate averaging 0.9gNH4 -N/m2 day (3.7gNH4 -N/m3 day), and temperatures ranging from 1.6 to 20.8°C. The system showed an extended seasonal nitrification period compared with a simulated aerated lagoon system of the same dimensions. This extension of complete nitrification with approximately 1month was observed in the fall despite the decrease of operating temperature down to 4°C. During this maximum nitrification period, substantial denitrification occurred, and the effluent un-ionized ammonia ratio was reduced. A temporary loss of nitrification was also experienced in relation to an episode of elevated suspended solids concentration. Measured biofilm characteristics, namely the detachment dynamics and the biofilm thickness, were used to explain this temporary nitrification loss. During wintertime, a low nitrate production was still observed, suggesting year-long retention of nitrifying bacteria in the biofilm. PRACTITIONER POINTS: Nitrification in a highly loaded biofilm-enhanced aerated lagoon is mainly affected by operating temperature. Maximum nitrification is observed during the warmer months and occurs even at high organic loading rates (>5gCBOD5 /m2 day). Compared with a simulated suspended growth system, the biofilm-enhanced lagoon shows a significantly extended nitrification period. The extension is observed at the end of the summertime maximum nitrification period. Low amounts of nitrate still produced during winter in the biofilm-enhanced aerated lagoon suggest year-long retention of autotrophic nitrifying biomass in the biofilm. Nitrification in the biofilm-enhanced aerated lagoon is negatively impacted by the presence of important quantities of accumulated solids that resuspend when their digestion starts as temperature increases.

Prey preference, environmental tolerances and ichthyotoxicity by the red-tide dinoflagellate Noctiluca scintillans cultured from Tasmanian waters

AbstractThe large phagotrophic dinoflagellate Noctiluca has become a prominent red tide organism in southeast Australian waters since the 2000s, raising concerns for beach tourism, grazing impacts as well as ichthyotoxicity for finfish aquaculture. Satisfactory culture growth rates (0.23–0.56 per day) were obtained by feeding with small Thalassiosira diatom and Tetraselmis flagellate diets, while optimal growth rates sustained for up to 8 months (0.69 per day) were achieved by feeding in a plankton wheel with the large chain-forming dinoflagellate Gymnodinium catenatum. Noctiluca was highly tolerant towards salinities from 20 to 35 and growth was stimulated by temperatures increasing from 10 to 23°C, which in combination with the key factor of prey abundance explains the incidence in southeast Australia of predominantly summer and spring but occasionally also winter blooms. Fatty acid biomarkers suggest that Tasmanian field populations indiscriminately feed on available diatom and dinoflagellate mixtures. Noctiluca exhibited very limited ichthyotoxicity, and only at the highest cell concentrations of 2 000 000/L (50% reduction in RTgill W1 cell viability). Only the densest red tide surface slicks contained acutely toxic levels of unionized ammonia of 242 to 510 μg/L while inshore slicks generated oxygen concentrations as low as 0–1.5 ppm. Lipid phycotoxins (eicosapentaenoic acid, docosahexaenoic acid) did not appear to contribute to Noctiluca ichthyotoxicity. The fatty acid 20:0 eicosanoic acid may serve as a potential Noctiluca biomarker in marine food webs and sediments.

Acute ammonia toxicity and the interactive effects of ammonia and salinity on the standard metabolism of European sea bass (Dicentrarchus labrax)

Ammonia tolerance of European sea bass (Dicentrarchus labrax) juveniles (1.1 ± 0.3 g) was investigated by a series of acute toxicity experiments at different salinity levels (10, 20 and 30 ppt) at pH 8.0 and temperature 22 °C. Oxygen consumption rates were also measured to determine the Standard Metabolism (SM) of the fish. The tolerance of the fish to total ammonia nitrogen (TAN) and unionized ammonia (NH3) increased significantly with increasing salinity levels. The safe level for European sea bass was estimated to be 0.4, 1.0 and 1.6 mg L−1 for TAN and 0.02, 0.04 and 0.07 mg L−1 for NH3 at 10, 20 and 30 ppt salinity levels, respectively. At any, each level, the SM of the fish increased with increasing TAN concentration (P < .01). The SM of the fish at 10, 20 and 30 ppt gradients is 284, 282 and 272 mg h−1 kg−1, respectively at 0 mg L−1 TAN concentration (P < .01). This study indicates that European sea bass, a euryhaline teleost fish, has a low tolerance to ammonia at any salinity level.

Effects of dietary arginine supplementation on ureagenesis and amino acid metabolism in common carp (Cyprinus carpio) exposed to ambient ammonia

The aim of the present study was to determine the effects of dietary arginine supplementation on resistance and responses to ammonia toxicity in common carp (Cyprinus carpio). In the first experiment, the fish were fed with four diets supplemented with 0% (control diet), 0.25% (0.25Arg), 0.5% (0.5Arg) or 1% (1Arg) for 14 days and challenged with 0.7, 0.8, 0.9, 1.1, 1.3 mg/L water unionized ammonia for 3 h. The results showed that 0.7 mg/L ammonia caused no mortality in the treatments, but 1.3 mg/L ammonia killed all the fish. In the second experiment, the fish fed either the control or the 0.5Arg diet for 14 days and exposed to 0.7 mg/L ammonia for 3 h, and plasma ammonia and free amino acids were determined. The results showed that arginine administration significantly increased plasma arginine, urea, ornithine, glutamate, aspartate and histidine, whereas decreased plasma ammonia, citrulline, glutamine and other amino acids except for glycine, asparagine and serine. Ammonia exposure led to significant elevations in plasma ammonia and urea, and significant declines in plasma arginine, ornithine, citrulline and other amino acids. In conclusion, common carp is ureagenic under ammonia exposure and tries to detoxify ammonia by converting to urea, as well as formation of glutamine. To keep glutamate levels constant during ammonia toxicity, common carp may utilize alanine, aspartate, glycine and serine for α-ketoglutarate formation as a substrate for glutamate synthesis. Arginine administration provides high levels of ornithine, which is used to convert ammonia to urea after ammonia toxicity. The benefits of arginine in common carp resistance to ammonia toxicity seem to be related to its stimulatory effects on ureageneis; however, other health benefits of the amino acid (anti-stress, antioxidant and anti-anemic) should not be neglected.

Sensitivity of the Marine Calanoid Copepod Pseudodiaptomus pelagicus to Copper, Phenanthrene, and Ammonia.

There are limited acute toxicity test methods for native North American marine species that are considered zooplankton for their entire life cycle. Examples of standardized marine zooplankton methods include mussel, bivalve, and echinoderm development tests that use a relatively short-lived planktonic larval stage, chronic life-cycle toxicity tests using epibenthic copepods, and a 24-h Acartia tonsa copepod test method. The objectives of the present study were to: 1) develop and evaluate a novel, 48-h acute toxicity test method using the marine North American copepod Pseudodiaptomus pelagicus that is planktonic for its entire life cycle, and 2) determine the sensitivity of P. pelagicus relative to commonly tested marine toxicity test species. The average (±1 standard deviation) median lethal concentrations (LC50s) for copper (Cu), phenanthrene, and un-ionized ammonia were 32 ± 15 µg/L, 161 ± 51 µg/L, and 1.08 ± 0.30 mg NH3 /L, respectively. These results placed P. pelagicus on the more sensitive end of Cu and phenanthrene species sensitivity distributions. The copepod was less sensitive to un-ionized ammonia than commonly tested marine species. This finding suggests that the acute P. pelagicus test method will allow a focus on assessing the impacts of persistent contaminants of concern with less confounding impact from naturally occurring ammonia released to the water from sources such as suspended sediments. Environ Toxicol Chem 2019;38:1221-1230. Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Antioxidant, enzymatic and hematological responses of common carp (Cyprinus carpio) fed with myrcene- or menthol-supplemented diets and exposed to ambient ammonia

Ammonia toxicity is common and risk factor in aquaculture, deteriorating fish health. Phytochemicals might attenuate adverse effects of ammonia toxicity in fish. The present study aimed to investigate the effects of dietary myrcene and menthol administration on common carp (Cyprinus carpio) health in response to ammonia toxicity. The fish were fed with either myrcene- or menthol-supplemented diets for 30 days before exposure to 0.5 mg/L unionized ammonia for 24 h. The experimental diets contained 0, 0.1, 0.25, 0.5 and 1% of either myrcene or menthol. Growth performance was determined after the 30-d feeding trial and the fish were blood-sampled before and after the ammonia challenge. The results showed that myrcene at 0.5% significantly improved the fish growth performance compared to the control diet (29.3 vs. 41.2% weight gain); however, menthol had no significant effects on the fish growth performance. Ammonia exposure led to significant decrease in plasma catalase, glutathione peroxidase, blood RBC and hemoglobin and significant increase in plasma superoxide dismutase, malondialdehyde, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase, which are indicators of oxidative stress, tissue damage and anemia. Myrcene at 0.25–1% and menthol at 0.25% levels significantly improved most of the tested parameters. Moreover, myrcene at 0.5 and 1% significantly inhibited the adverse effects of ammonia exposure on the fish antioxidant responses, tissue health and anemia; however, menthol was less effective compared to myrcene and the most effective concentration was 0.25%, which mitigated the adverse effects of ammonia exposure. In conclusion, myrcene at 0.5% and menthol at 0.25% levels are effective in reducing the adverse effects of ammonia toxicity in common carp. Such effects seem to be related to the compounds antioxidant effects, which mitigated ammonia-induced tissue damage and anemia.

Impact of holding time on toxicity change of urban road dust during runoff process

During runoff process, the urban road dust (URD) passes through the road-side gutters and detention tanks, where it gets hold for a certain period of time, hours to weeks, before making its way into the water bodies. A part of the water-exchangeable toxicants are leached by the water, and some strongly bound toxicants remain attached to the URD. Toxicity of urban runoff is dependent on holding time, water volume, and the type and composition of the wet road dust (WeRD) and leachate. However, there are no studies that have elucidated the manner in which toxicities of the WeRD and leachate vary during prolonged holding in the runoff processes. The main objectives of this research were to, i) identify the distribution of toxicants in the WeRD and leachate, and ii) evaluate the change in toxicity during prolonged holding. The URD samples that were collected from residential road, arterial road and highways in Tokyo, Japan, were mixed with moderately hard water in varying ratios (1:2 to 1:16) and were held for a certain time (1h to 5days) before centrifuging into the WeRD and leachate. Toxicity test was conducted with ostracod Heterocypris incongruens direct contact test. Toxicity of both the WeRD and leachate from residential area was not significantly greater than the 20% lethal limit. Toxicity of the WeRD from other stations initially decreased, further reached a minimum corresponding to the critical holding time, and it subsequently increased again. Toxicity of the arterial leachate gradually increased, whereas that of the highway leachate gradually decreased during 5days holding. Unionized ammonia and zinc were confirmed as one of the possible toxicants. This study proposes and verifies a model for the toxicity change of the WeRD during prolonged holding.

Cytokines' gene expression, humoral immune and biochemical responses of common carp (Cyprinus carpio, Linnaeus, 1758) to transportation density and recovery in brackish water

The aim of the present study was to investigate the effects of stocking density during transportation and post-transportation salt treatment on stress, hydromineral, immunological and antioxidant responses in common carp (Cyprinus carpio). For this, the fish were transported in plastic bags for 4 h at two densities: 100 (LD) and 200 (HD) g/L and allowed to recover for 24 h in both freshwater (FW) and brackish water (3 g/L sodium chloride; BW). Water physicochemical parameters were determined after transportation. Blood stress, immunological and hydromineral responses, head kidney cytokine gene expression, and liver antioxidant responses were determined. The transportation led to significant decrease in water dissolved oxygen and pH, and increase in water total and unionized ammonia levels. Water dissolved oxygen was significantly lower, whereas, water total and unionized ammonia were significantly higher in the HD, compared to the LD group. Serum cortisol and glucose, and liver malondialdehyde levels, and expression of tumor necrosis factor-alpha, interleukin-1beta and interleukin-8 genes increased after transportation. Serum ion levels and liver superoxide dismutase and catalase decreased after transportation. All the above-mentioned changes, except for cortisol and catalase, were more severe in the HD compared to the LD group. There were no significant changes in serum total immunoglobulin and alternative complement after transportation, compared to before transportation values; but the LD group had significantly higher alternative complement than the HD group. Lysozyme and WBC significantly increase in the LD group; whereas, significantly decreased in the HD group, after transportation. Recovery in BW was useful to mitigate stress response, hydromineral imbalance, immunosuppression and oxidative stress caused by the transportation. Using sodium chloride is recommended during fish recovery from transportation, particularly when the fish are transported at high stocking density. The benefits of sodium chloride treatment seem to be mediated by restoration of hydromineral balance and oxidative status, which leads to healthier fish with higher immune responses.

Molecular Characterization of Vibrio Harveyi and Vibrio alginolyticus with the Impact of Stressful Environment on Some Naturally Infected Marine Fish

Cultured seabass (Dicentrarchus labrax L.) and seabream (Sparus aurata L.) are marine species of high economic important especially in Mediterranean aquaculture. Among bacterial diseases of marine cultured and wild fish, vibriosis caused by Vibrio species is one of the most prevalent diseases. In the present work, we report the isolation and identification of the V. harveyi and V. alginolyticus, based on biochemical and molecular characterization, from cultured seabass and seabream native to private fish farms at Mathalath-El Diba region, Domitte City at Domitte Governorate, Egypt during summer season. The most prominent clinical signs of diseased fish were hemorrhagic ulceration on the dorsal musculature and caudal peduncle area as well as sever protrusion of the eye outside the orbital cavity. Histological examination of seabass revealed haemorrhage on the liver and nodular formation on different organs especially in kidney and liver. While, diseased seabream showed marbling appearance of gill with nodular formation and necrotic area distributed over the liver. Physico-chemical characteristics of water samples collected parallel to fish samples indicated that pH and organic matter of the water sample was within the permissible limits. However, the unionized ammonia, nitrate, and hydrogen sulphate concentrations were higher than the acceptable limits. Moreover, the heavy metals (copper, zinc, cadmium, lead, mercury, nickel, and iron) contained of water samples were higher than permissible limits. In regards to the haematological parameters associated with diseased and apparently healthy seabream and seabass. The total protein, albumin, and globulin were lower in diseased seabass and seabream than apparently healthy fish. Serum lysozyme and bactericidal activity was lower in the diseased fish than apparently healthy seabass and seabream. Levels of aspartate amino-transferase (S.AST) and alanine amino transferase (S.ALT) in plasma of diseased seabass and seabream were higher than apparent healthy seabass and seabream. Altogether, higher level of heavy metal concentrations in water samples than the permissible limits act as chemical stressors that help in increase the prevalence of V. harveyi and V. alginolyticus species in seabass and seabream.

Protective effect of high hardness in pacu juveniles (Piaractus mesopotamicus) under acidic or alkaline pH: Biochemical and haematological variables

The relationship between water pH and hardness influences fish physiology, where increasing water hardness could trigger a protective effect for fish exposed to acidic or alkaline pH. Hence, this study aimed to investigate pacu (Piaractus mesopotamicus) for the existence of a protective effect of high water hardness at acidic and alkaline pH. Pacu exemplars were exposed to low (LWH, 50 mg CaCO3 L−1) or high water hardness (HWH, 120 mg CaCO3 L−1) at acidic (5.5), circumneutral (7.5) or alkaline (9.0) pH, for 15 days. Un-ionised ammonia was the highest at the alkaline pH, and alkalinity was the lowest at the acidic pH. Blood pH levels were lowest at alkaline pH, mainly when fish were subjected to HWH. The HWH presented a protective effect for pacu exposed to acidic or alkaline pH, as verified in the blood glucose and lactate, and plasma total ammonia levels on day 1, total plasma protein levels on day 5, and total ammonia and alkaline phosphatase levels in plasma on day 15. Values of haematocrit, haemoglobin and haematimetric indices, were typically increased in fish exposed to alkaline or acidic pH in LWH throughout the experiment, which, in turn, was not verified for fish exposed to HWH. In conclusion, pacu can cope with acidic or alkaline conditions, but acidic and alkaline pHs under LWH are stressful. The combination of acidic or alkaline pH with HWH triggered a protective effect because biochemical and haematological variables of pacu juveniles showed few changes in fish exposed to circumneutral pH.

Effect of two commercial probiotic products on population growth of rotifer Brachionus rotundiformis Tschugunoff

The application of probiotics has varying effects on rotifer culture. These effects can either be directly on their growth and reproduction or indirectly by affecting the culture environment. The role played by specific probiotic candidates is still indistinct and further research is required to ascertain their significance in rotifer culture. In this study, euryhaline rotifer Brachionus rotundiformis (SS-type) was used to evaluate the effect of two commercial probiotic products on rotifer density, reproductive parameters and unionized ammonia concentration for a twelve-day culture period. To estimate these parameters, rotifers were cultured in glass bottles containing dilute sterilized sea water with the following five diet treatments: Nannochloropsis oculata (control), Igsign (PB1), Toaraze Aqua (PB2) or the combination of N. oculata with either PB1 or PB2. The rotifer density was significantly affected by the addition of probiotic. N. oculata + PB2 treatment resulted in higher rotifer density and specific growth rate compared to the control treatment. Mixis induction was unaffected by N. oculata + PB2 while it was repressed by N. oculata + PB1. Ammonia concentration was not significantly affected with the addition of probiotics. These results indicate that probiotics have synergetic effects with microalgae diet that resulted in the highest rotifer densities.