The toxicity effects of the individual and combined exposure of methyl tert-butyl ether (MTBE) and tire rubber powder (RP) on Nile tilapia fish (Oreochromis niloticus)

Methyl tert-butyl ether (MTBE) is soluble in water and can contaminate water sources when it spills during transportation or leaks from underground storage tanks. Incomplete combustion releases MTBE as exhaust fumes that can be deposited on urban surfaces. Meanwhile, car tires erosion emits of large amounts of rubber dust (RP), easily transported to water bodies. Therefore, this study has the objective of assessing the toxicity of varying concentrations of MTBE (0, 2.5, 5.0 μL L-1) and RP (0, 5.0, 10.0 mg L-1 RP), both individually and in combination, over a period of 28 days on Nile tilapia (Oreochromis niloticus). MTBE and PR decreased fish growth performance. Blood biochemical analytes indicated that MTBE and RP led to increasing Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and creatinine phosphokinase (CPK), alkaline phosphatase and gamma-glutamyl transferase (GGT) activities. Alterations related to glucose, triglycerides, cholesterol, and creatinine, plasma contents, were also observed. Increased antioxidant biomarkers, including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), glutathione reductase (GR), and malondialdehyde (MDA), was observed. Exposure fish to MTBE and PR changed metabolic profile of muscle tissue. Moreover, results showed that MTBE, its metabolites, and PR could accumulate in the muscle tissue of fish. Results suggest that MTBE and RP can impact fish health, both individually and when combined. The presence of MTBE enhances the toxicity of RP, indicating a synergistic effect. Nevertheless, further studies are needed to understand the impact of toxic compounds on aquatic environments and organisms' health.

Interaction of low-level dietary supplementation of Chlorella vulgaris Beijerinck, 1890, and feeding duration on growth hormone, growth performance and serum biochemistry of red hybrid tilapia (Oreochromis mossambicus × Oreochromis niloticus)

Chlorella is one of the most widely accepted Chlorophyta used by many as livestock and aquaculture feed. Nonetheless, different studies on the overall performances of fish reported the unfavourable effect of high-level supplementations of Chlorella vulgaris. The current study determined the impact of low-level dietary supplementation of C. vulgaris alongside the different feeding durations and their interactions on the growth hormone (GH), growth performances, serum-biochemical indices, hepatic function and some immunological parameters of red hybrid tilapia. The fingerlings (mean weight: 14.25 ± 0.01 g, length: 13.5 ± 0.49 cm) were fed diets containing 0, 0.99%, 2.91% and 4.76% of C. vulgaris powder per kilogram dry diet for 90 days. GH, growth performance, serum-biochemical indices (total serum protein, albumin, globulin, glucose, aspartate aminotransferase and alanine aminotransferase) and some immunological (respiratory burst and lysozyme activities) parameters of the fish were examined after 30, 60 and 90 days of feeding. The results demonstrated that tilapia fed C. vulgaris-supplemented diets showed increased levels of respiratory burst, lysozyme, albumin and total protein, GH and growth performances (P < 0.05), and the effects were duration dependent. After the 90 days of feeding, there was no adverse effect on the hepatic function of the fish. Besides, low survivability was observed in the control group than in the group fed the experimental diets. The group fed the diet supplemented with 4.76% C. vulgaris had significantly higher (P < 0.05) lysozyme activity throughout the duration of the feeding experiment. These results indicate that C. vulgaris enhanced growth performances, GH concentration, serum-biochemistry and some immunological parameters of red hybrid tilapia.

Data on growth performance, glucose concentration and testosterone level of Asian seabass, Lates calcarifer juveniles fed with exogenous melatonin at different concentration

This data article describes the growth performance, glucose concentration in blood and testosterone level in plasma of juvenile Asian seabass (Lates calcarifer) after being fed with exogenous melatonin at different concentrations (0, 50 and 100 mg kg-1). To collect the data, 160 juveniles (60 days old) with an initial mean weight of 20.54 ± 7.16 g and mean length 11.14 ± 0.05 cm were reared in 1800 L rectangular fibreglass aerated tanks of a recirculating aquaculture system (n = 40 fish/ tank/ treatment) for 90 days. Four different treatments were tested: basal diet without any hormone (Control), basal diet with ethanol solution (Control + Ethanol; vehicle control), basal diet sprayed with 50 mg/kg feed of melatonin (Melatonin (50 mg/kg of diets)) and basal diet sprayed with 100 mg/kg feed of melatonin (Melatonin 100 mg/kg of diets). Initial and final body weight and body length of fish was measured and recorded to calculate the data of weight gain (WG). At the end of the feeding trial, the juveniles blood glucose and testosterone level were analyzed. Normality test, One-way ANOVA analysis followed by Tukey post-hoc test were then performed on the data obtained from the calculation of WG, survival rate, blood glucose and testosterone level. The data presented in this article will helps farmers and scientist to optimize the usage of melatonin administration in Asian seabass juveniles.

Analyses of the health status, risk assessment and recovery response of the nutritionally important catfish Clarias batrachus reared in coal mine effluent-fed pond water: a biochemical, haematological and histopathological investigation

The present field study evaluates the health status of the catfish Clarias batrachus reared in coal mine effluent (CME)-fed pond water at Rajrappa mining complex using biochemical, haematological and histopathological parameters. Simultaneously, risk assessment along with recovery response of the CME intoxicated fish following their treatment with CME-free freshwater was also studied. The CME-fed pond water fish revealed significant decrease in biomolecules concentrations and considerable increase in activities of several enzymes along with metallothionein level as compared to control. The impaired regulation of metabolic function was also revealed by blood parameters showing significant decrease in haemoglobin content (8.78 ± 0.344 g/100 mL) and red blood cells count (1.77 ± 0.12 × 106 mm3) while substantial elevation in white blood cells (187.13 ± 9.78 × 103 mm3). The histopathological study also confirmed the changes including hypertrophy of club cells of skin, swelling of secondary lamella of gills, extensive fibrosis in liver and glomerular shrinkage with increased Bowman's space in kidney. Potential health risk assessments based on estimated daily intake and target hazard quotient indicated health risks associated with the consumption of such fishes. The CME-contaminated fish when transferred to CME-free freshwater exhibited decreased metal content accompanied by eventual recovery response as evident by retrieval in biochemical and haematological parameters. Withdrawal study also revealed restoration in the activity of different marker enzymes in fish tissues including blood as well as recovery in their cellular architecture. The results of the present study validate the depuration process as an effective practice for detoxification of fish contaminated with effluent.

Technical suitability and reliability of an in vivo and non-invasive biosensor-type glucose assessment as a potential biomarker for multiple stressors in fishes: an evaluation on Salmonids

Regardless of the wide use of glucose measurements in stress evaluation, there are some inconsistencies in its acceptance as a stress marker. To meet the challenge and test the reliability/suitability of glucose measurement in practice, we simulated different environmental/anthropogenic exposure scenarios in this study. We aimed to provoke stress in fish followed by a 2-week stress recovery period and under the cumulative effect of leachate fish exposed to pathogenic oomycetes (Saprolegnia parasitica) to represent a possible infection in fish. We selected stream-resident and anadromous brown trout ecotypes (Salmo trutta) representing salmonids with different migratory behaviour strategies. Here, we analysed glucose content in fish-holding water, blood and gills to determine glucose suitability as a potential biomarker of fish response to environmental challenges. Additionally, swimming behavioural parameters and haematocrit were measured. The results indicated that the quantity of glucose released in the holding water of stressed fish increased considerably and remained substantially higher throughout the stress recovery period than the control level. Correspondingly, the circulating levels of glucose in blood and gills decreased over time in fish exposed to different stressors. A significant decrease in swimming activity of fish was observed during the first hours of leachate exposure and increased in fish exposed to S. parasitica compared to control. Our study is the first to ensure the validity and reliability of glucose response in evaluating physiological stress in fish under chemical and biological stimuli, indicating its sensitivity and response range of glucose measurement in fish-holding water.

Toxicological responses of juvenile Chinese shrimp Fenneropenaeus chinensis and swimming crab Portunus trituberculatus exposed to cadmium

Cadmium (Cd) is one of the typical metal pollutants in the Bohai Sea. To evaluate the acute toxicological effects of Cd on marine crustaceans, juvenile Fenneropenaeus chinensis and Portunus trituberculatus were exposed to Cd at environmentally relevant concentrations (5 and 50 μg/L) for 96 h. Cd accumulation, antioxidants and metabolite profiles were characterized to elucidate the responses of juvenile crustaceans to Cd stress. Significant Cd accumulation was observed in both juvenile crustaceans in 50 μg/L Cd-treated group. Results showed that Cd exposure induced hormesis based on the alterations of GSH, SOD and CAT activities (i.e. increased levels in the low concentration of Cd treatment and recovered levels in the high concentration of Cd treatment) in juvenile P. trituberculatus. Similarly, the responses of GSH contents presented hormesis pattern in Cd-treated juvenile F. chinensis. Na+-K+-ATPase contents were significantly elevated in 50 μg/L Cd-treated group. In addition, untargeted NMR-based metabolomics indicated Cd caused the disturbance in osmotic regulation and energy consumption in both juvenile F. chinensis and P. trituberculatus via different pathways. The immunotoxicity and movement disorder were uniquely demonstrated in juvenile P. trituberculatus after Cd exposure.

2D-DIGE proteomic analysis of blood plasma reveals changes in immune- and stress-associated proteins following hormonal stimulation of carp males

In carp aquaculture, hormonal manipulation with an analog of GnRH (Ovopel) and carp pituitary extract (CPE), which act at different levels of the hypothalamic-pituitary-gonadal axis, is a routine practice to enhance sperm production. Our recent studies revealed that hormonal stimulation of male carp was associated with changes in the seminal plasma proteome, including blood origin proteins. Here, we explored whether Ovopel and CPE could affect the blood proteome of male carp. Both preparations induced increases in semen volume, total number of sperm, and testosterone level. However, hormonal stimulation did not affect the plasma cortisol and glucose levels. A comparative proteomic analysis of carp blood plasma between the control (PBS) and the hormonally treated males revealed significant changes (>1.2 <-1.2-fold change, P < 0.05) in the abundance of 30 spots (14 up- and 16 downregulated) and 44 spots (28 up- and 16 downregulated) upon CPE and Ovopel treatment, respectively. The most significantly affected pathways were acute phase response signaling, the coagulation system, LXR/RXR and FXR/RXR activation; however, there were different sets of proteins in Ovopel- and CPE-treated males. The majority of differentially abundant proteins were involved in the regulation of the immune defense response, the response to stress, and complement activation. Moreover hormonal stimulation with CPE markedly increased the bactericidal activity of blood and both preparations caused profound changes in gene expression in hematopoietic organs. This work is important in understanding the biological processes behind the protein-based response to hormonal stimulation of sperm production in fish.

Assessing the impacts of in-feed probiotic on the growth performance and health condition of pangasius (Pangasianodon hypophthalmus) in a farm trial

The effects of in-feed probiotics on growth performance, haematological parameters, gut microbial content, and morphological changes to pangasius fish were assessed. The trial had three phases, i.e., larvae to fry (20 days), fry to fingerlings (45 days), and grow-out phase from fingerlings to marketing (90 days). The stocking densities were 400 m^-3, 200 m^-3, and 12 m^-3 for phases 1, 2, and 3, respectively. Phases 1 and 2 were conducted in hapas in the same pond, whereas phase 3 was performed in concrete tanks. The in-feed probiotic was administered at a rate of 0.2 g kg^-1 of feed three times per day in phases 1 and 2 only. In phase 3, in-feed probiotics was not applied to any groups. The treated group exhibited higher growth performances (p < 0.05) than the control in all three phases of experiment. The survival % in phase 1 and 2 were found significantly (p < 0.05) higher in treatment groups. This indicates that pangasius nurserers would benefit from using probiotics as a safeguard to increase fry survival to a greater extent. Two haematological parameters including red blood cells (RBC) and white blood cells (WBC) levels were found significantly (p < 0.05) higher in treated groups in phase 2 and 3, while glucose and hemoglobin level were found significantly (p < 0.05) higher in the treated groups during phases 2 and 3, respectively. The gut microbiota content was relatively higher in the treated groups in phase 2 and 3. Histological findings indicate that the use of probiotics during the nursing phases of pangasius induced a positive change in the intestinal morphological structures. The positive impacts of probiotics on the phase 3 confirmed an immediate and long-term growth performance and health of pangasius.

The effects of dietary clinoptilolite and chitosan nanoparticles on growth, body composition, haemato-biochemical parameters, immune responses, and antioxidative status of Nile tilapia exposed to imidacloprid

This study aimed at the evaluation of the mitigating effects of dietary zeolites (ZEO) and/or chitosan nanoparticle (ChNP) on imidacloprid (IMID)-induced toxicity in Nile tilapia (Oreochromis niloticus). Fish (18.03 ± 0.01 g) were allocated into six groups; one fed on a basal diet (control) (CTR), and the other groups were fed diets supplemented with ChNPs (5 g kg^-1) and/or ZEO (20 and 40 g kg^-1) (ZEO₂₀ and ZEO₄₀) for 60 days. In the last 14 days of the experiment, all groups were exposed to a sub-lethal dose of IMID (½ of 96 h LC₅₀ = 0.0545 μg L^-1). Dietary ZEO₂₀ significantly improved all growth parameters (P ˂ 0.05), while ChNPs had no significant effects. The crude protein of the fish body was significantly increased in all groups compared to the CTR (P ˂ 0.05). No significant impacts of ChNPs, ZEO, and their interaction (P > 0.05) were noticed on the moisture, dry matter, and ash percentages. Compared to the CTR, hematocrit values were significantly decreased (P ˂ 0.05) in ChNP and ZEO₂₀ groups; meanwhile, their levels were significantly increased (P ˂ 0.05) in the ZEO₄₀ group and all combined treatments. Fish fed diets with ChNPs and/or ZEO had significant increments in the MCV values (P ˂ 0.05). Moreover, fish fed diets supplemented with ChNPs or their combination with ZEO had the lowest glucose and alkaline phosphatase levels compared with the CTR. Serum aspartate transferase levels were significantly decreased in all treated groups (P ˂ 0.05) compared to the CTR. ChNPs alone or combined with ZEO significantly exhibited the highest lysozyme and nitro blue tetrazolium values (P ˂ 0.05). On the other hand, fish in the CTR group had the highest malondialdehyde and lowest nitric oxide levels compared to the other groups. Interestingly, the lowest IMID residues in fish flesh were found in fish groups fed diet with a combination of ZEO and ChNPs. Partial or complete protection of the hepatic and splenic tissues were observed in fish group with combined treatment with ChNPs and ZEO. In conclusion, the application of ZEO and/or ChNPs in Nile tilapia diets looks to be a leading approach to mitigate the toxic impacts of IMID.

Effects of Activated Charcoal on Growth, Immunity, Oxidative Stress Markers, and Physiological Responses of Nile Tilapia Exposed to Sub-Lethal Imidacloprid Toxicity

Simple Summary

Finding a suitable feed supplement is important for maintaining fish health and sustainability of the aquaculture industry. From these supplements, research studies have shown that activated charcoal (AC) has been extensively used for veterinary and aquaculture objectives as a “Universal Antidote” against several toxicants and aquatic pollutants. Therefore, the mitigating roles of dietary supplementation with different AC levels on physiological responses of Nile tilapia exposed to sub-lethal imidacloprid (IMID) toxicity were evaluated. The findings of this study revealed that dietary supplementation with 14.30 g AC/kg diet positively modulated the toxic impacts of IMID-intoxicated fish.

Abstract

The existing study was designed to assess the influences of dietary activated charcoal (AC) on the growth performance, immune responses, antioxidative status, and its mitigating roles against the physiological responses of Nile tilapia exposed a sub-lethal dose of a neonicotinoid agriculture pesticide, namely, as imidacloprid (IMID). Nile tilapia juveniles were fed on diets supplemented with graded AC levels as 0 (control), 5, 10, 15, and 20 g/kg diet for eight weeks. Growth, hemato-biochemical indices, and antioxidant and immune responses of fish in all groups were evaluated at the end of the feeding experiment. Afterward, fish in all experimental groups were subjected to a sub-lethal dose of IMID (0.0109 μg/L) for two weeks. Then, fish mortalities, stress indicators, and IMID residual levels in liver and flesh were examined. Results of the feeding experiment showed that total feed intake, weight gain, final body weights, and feed efficiency ratio were significantly increased in all AC groups compared with the control group. The survival rate was 100% in all experimental groups. No statistical differences were observed in the hematological picture of all experimental groups except the lymphocyte count, which was significantly increased in all AC groups compared to the control group. Total protein, albumin, globulin, nitric oxide levels, lysozyme, and respiratory burst activities were significantly increased in all AC groups. Serum alanine transaminase, aspartate transaminase, alkaline phosphatase activities, and malondialdehyde (MDA) levels were significantly decreased in all AC groups compared with the AC0 group. After exposure to a sub-lethal dose of IMID, survival rates were significantly elevated, and IMID residual levels in liver and flesh were significantly decreased in all AC groups than in the control group. Moreover, second-order polynomial regression showed that dietary supplementation with 14.30 g AC/kg diet resulted in the lowest blood glucose and serum MDA levels. Conclusively, we suggest dietary supplementation with 14.30 g AC/kg diet to modulate physiological responses of Nile tilapia to sub-lethal IMID toxicity.

Juvenile fish responses to sublethal leachate concentrations: comparison of sensitivity of different behavioral endpoints

The aim of the present study was to investigate changes in the locomotor activity of rainbow trout (Oncorhynchus mykiss) juveniles under the impact (2 h) of landfill leachate (as a multicomponent mixture) based on different endpoints such as average, maximum and angular velocities, movement duration, body mobility, and blood glucose level. Fish were exposed to five different sublethal leachate concentrations (0, 0.0625, 0.125, 0.25, and 0.5%). The locomotor activity of the leachate-exposed fish significantly decreased at 0.25 and 0.5% concentrations. Significant changes in fish behavior in response to sublethal leachate concentrations were determined during the first minutes of exposure. Angular velocity proved to be the most sensitive of all the endpoints tested. A positive correlation was observed among behavioral responses, but no correlation was established between the blood glucose level and behavioral endpoints. The blood glucose endpoint was found to be insensitive, and we suggest that it should be used only in combination with other endpoints to complement toxicity data. To enhance the understanding of rainbow trout behavioral characteristics in relation to time, and relations among behavioral endpoints of the fish under short-term exposure to a multicomponent mixture, in the current study, we investigated dynamics of the selected behavioral endpoints over time, relations among these endpoints and compared behavioral response rapidness and efficacy.

Responses of biomarkers in Atlantic salmon (Salmo salar) following exposure to environmentally relevant concentrations of complex metal mixture (Zn, Cu, Ni, Cr, Pb, Cd). Part II

The aim of this research was to assess interactions between metals at low exposure concentrations (Maximum-Permissible-Concentrations accepted for the inland waters in EU) and to assess possible influence of background exposure (10-times reduced concentration of a single metal) on toxicological significance of selected biomarkers in Salmo salar after treatment with metal mixture (Zn - 0.1, Cu - 0.01, Ni - 0.01, Cr - 0.01, Pb - 0.005 and Cd - 0.005 mg/L). The tissue-specific bioaccumulation, genotoxicity and cytotoxicity responses (erythrocytic nuclear abnormalities assay) in peripheral blood, kidneys, gills and liver erythrocytes of fish to metal mixtures were assessed after 14 days treatment. Treatment with primary mixture (MIX) or two variants of this mixture (Cr↓ (10 times reduced Cr⁶⁺ concentration) and Cu↓ (10 times reduced Cu²⁺ concentration)) induced the strongest responses in genotoxicity and cytotoxicity endpoints. Exposure to these mixtures highly affected Zn, Cu and Cd bioaccumulation in liver tissue. The highest amount of Ni accumulated was measured after Cd↓ treatment in all tissues. Treatments with reduced concentration of non-essential metal resulted in an increased accumulation of Pb, Ni, or Cd; treatments with reduced concentration of essential metal resulted in a reduced accumulation of certain metals (especially Cd and Pb) in tissues compared between treatments. Glucose content in blood and behavioural endpoints were evaluated after short-term exposure to metal mixtures (MIX, Cr↓, Cu↓). Significant increase in blood glucose concentration was measured after all treatments. These metal mixtures elicit significant behavioural alterations in fish. Consequently, this research revealed a significant influence of background exposure considering mixture toxicity.