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Methylene blue (MB) can have inhibitory effects against protozoan and fungi in fish. In this investigation, fish were first exposed to different MB concentrations (0 and 2 mg L−1) for 21 days. Then, the fish were challenged with Aeromonas hydrophila for 7 days. Some haemato‐immunological and biochemical parameters, oxidative stress biomarkers in blood, growth performance and fish resistance to A. hydrophila were examined once a week. The results showed that erythrocyte, haemoglobin, leucocytes, haematocrit, mean corpuscular volume., mean corpuscular haemoglobin concentration and lymphocyte percentage significantly reduced in the fish after exposure to 2 mg L−1 MB on the 14th and 21st days and challenged period on 28th day. Although the superoxide dismutase, catalase, and glutathione peroxidase, lysozyme, phagocytic activities and a quantitative nitroblue tetrazolium, total protein and cellular total antioxidant levels in the serum decreased significantly, the percentage of neutrophils, aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities increased significantly in fish exposed to 2 mg L−1 MB (p < 0.05). There was a significant difference in the growth performance and the percentage of monocytes exposed to 2 mg L−1 of MB compared to the reference group. The mortality rate was declined in the treated fish with 2 mg L−1 of BM after challenge with A. hydrophila compared with the control group. Overall, the present results indicate some negative impacts of MB application in goldfish even at the therapeutic level. From these, the immunosuppressive effects of MB may be potentially disruptive for a health condition. [ABSTRACT FROM AUTHOR]

The accumulation of microplastics (MPs) is a growing problem in aquatic ecosystems. Despite increased research on MPs in the last decade, their potential threat to freshwater ecosystems remains an open question. In the present study, the negative impacts of MPs were investigated on blood biochemical parameters in the European pond turtle (Emys orbicularis). Pond turtles were distributed into three experimental groups (n = 9 for each group) and were fed diets containing 250, 500, and 1000 mg MPs (PE100 polyethylene) per kg of food for 30 days, and a control group fed with a standard uncontaminated diet. The results indicated that exposure to 500 and 1000 mg kg−1 MPs caused a significant increase in the activities of alanine and aspartate aminotransferases, and in the levels of cholesterol, glucose, creatinine, urea, and calcium (Ca+2) compared with the control group. On the contrary, the activity of gamma-glutamyl transferase and the levels of total protein, albumin, total immunoglobulins, and phosphorus were significantly reduced in E. orbicularis exposed to 500 and 1000 mg kg−1 MPs when compared with the controls. In all the MP-exposed groups, the activity of lactate dehydrogenase and globulin and magnesium (Mg+2) levels were significantly reduced; while creatine phosphokinase and alkaline phosphatase activities were increased with respect to the control turtles. A significant decrease in triglyceride levels was reported in E. orbicularis exposed to 1000 mg kg−1 MPs. MPs intake induced notable alterations in blood biochemical parameters of E. orbicularis. These results suggest that changes in the blood biochemical parameters could be an appropriate bio-indicator to evidence the existence of tissue damage in E. orbicularis. [ABSTRACT FROM AUTHOR]

Glyphosate is an herbicide that inhibits the growth of weed plants, while chlorpyrifos is an insecticide commonly applied to control the pests' population. This study aimed to investigate the combined effects of chlorpyrifos and glyphosate on biochemical, immunological parameters, and oxidative stress biomarkers in freshwater crayfish Pontastacus leptodactylus for 21 days. The experimental design of this study was factorial (3 × 3), including 0.0, 0.4, and 0.8 mg L−1 glyphosate and 0.0, 2.5, and 5 µg L−1 chlorpyrifos. The exposure to chlorpyrifos, glyphosate alone and a mixture of them significantly decreased acetylcholinesterase, alkaline phosphatase, phenoloxidase activities, and total protein levels. The lactate dehydrogenase, glutamic-pyruvic-transaminase, and catalase activities, the contents of glucose, and malondialdehyde levels were increased in the crayfish. No significant changes were detected in glutamic-oxaloacetic-transaminase (SGOT) activity, triglyceride, and total antioxidant (TAO) levels in the crayfish treated with 0.4 mg L−1 glyphosate and the control group. Co-exposure of crayfish to chlorpyrifos and glyphosate increased SGOT activity and TAO levels. Although chlorpyrifos combined with glyphosate decreased the γ-Glutamyltransferase (GGT) activity, the GGT activity was significantly increased in the P. leptodactylus exposed during 21 days to 5 µg L−1 chlorpyrifos alone and 0.8 mg L−1 glyphosate alone. In comparison with the reference group, no significant changes were evidenced in the cholesterol levels in the P. leptodactylus treated with 2.5 µg L−1 chlorpyrifos, but its levels were significantly increased in the other treatment groups. In conclusion, the mix of glyphosate and chlorpyrifos exhibited synergic effects on the different toxicological biomarkers in the narrow-clawed crayfish. Co-exposure to pesticides may result in disruption of homeostasis in the crayfish by altering the biochemical and immunological parameters. [ABSTRACT FROM AUTHOR]

Not long after plastic-made material became an inseparable part of our lives, microplastics (MPs) found their way into ecosystems. Aquatic organisms are one of the groups impacted by man-made materials and plastics; however, the varied effects of MPs on these organisms have yet to be fully understood. Therefore, to clarify this issue, 288 freshwater crayfish (Astacus leptodactylus) were assigned to eight experimental groups (2 × 4 factorial design) and exposed to 0, 25, 50, and 100 mg polyethylene microplastics (PE-MPs) per kg of food at 17 and 22 °C for 30 days. Then samples were taken from hemolymph and hepatopancreas to measure biochemical parameters, hematology, and oxidative stress. The aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, and catalase activities increased significantly in crayfish exposed to PE-MPs, while the phenoxy-peroxidase, gamma-glutamyl peptidase, and lysozyme activities decreased. Glucose and malondialdehyde levels in crayfish exposed to PE-MPs were significantly higher than in the control groups. However, triglyceride, cholesterol, and total protein levels decreased significantly. The results showed that the increase in temperature significantly affected the activity of hemolymph enzymes, glucose, triglyceride, and cholesterol contents. The semi-granular cells, hyaline cells, granular cell percentages, and total hemocytes increased significantly with the PE-MPs exposure. Temperature also had a significant effect on the hematological indicators. Overall, the results showed that temperature variations could synergistically affect the changes induced by PE-MPs in biochemical parameters, immunity, oxidative stress, and the number of hemocytes. [Display omitted] • The effect of temperature on the toxicity of PE-MPs on A. leptodactylus was assayed. • Temperature variations changed the hematological and biochemical indices in crayfish. • PE-MPs had a toxic effect on crayfish. • Temperature changes had a synergistic effect on the toxicity of PE-MPs. [ABSTRACT FROM AUTHOR]

This study investigated the toxicity of polyethylene microplastics (MPs; <0.02 mm) and CuSO4, alone and in combination, on the freshwater crayfish Pontastacus leptodactylus. In this study, the crayfish were exposed to PE-MPs (0.0, 0.5, and 1 mg L−1) and CuSO4·5H2O (0.0, 0.5, and 1 mg L−1) for a period of 28 days. Next, multi-biomarkers, including biochemical, immunological, and oxidative stress indicators were analyzed. Results showed that co-exposure to PE-MPs and CuSO4 resulted in increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and decreased alkaline phosphatase (ALP), butyrylcholinesterase (BChE), and gamma-glutamyl-transferase (GGT). Triglycerides, cholesterol, glucose, and albumin content also increased. Although no significant change was observed in lysozyme and phenoloxidase activities in crayfish co-exposed to 0.5 mg L−1 MPs and 0.5 mg L−1 CuSO4, their activities were significantly decreased in other experimental groups. Oxidative stress parameters in hepatopancreas indicated increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and in malondialdehyde (MDA) levels, but decreased catalase (CAT), glucose 6-phosphate dehydrogenase (G6PDH), and cellular total antioxidant (TAC). Results showed that the sub-chronic toxicity of CuSO4 was confirmed. The study confirmed the toxicity of CuSO4 and found that higher concentrations led to more severe effects. Co-exposure to PE-MPs and CuSO4 primarily compromised the endpoints, showing increased toxicity when both pollutants were present in higher concentrations. The activities of POX, LYZ, ALP, GGT, LDH, and CAT were suppressed by both CuSO4 and MPs. However, a synergistic increase was observed in other measured biomarkers in crayfish co-exposed to CuSO4 and MPs. [Display omitted] • Crayfish were exposed to PE-MPs and CuSO4, alone and in combination. • CuSO4 and PE-MPs, alone and combined, altered oxidative and biochemical biomarkers. • The toxicity of CuSO4 and PE-MPs on some biomarkers was dose-dependent. • Synergistic effects were observed in crayfish when co-exposed to CuSO4 and PE-MPs. • POX, LYZ, ALP, GGT, LDH, and CAT activities were suppressed by CuSO4 and PE-MPs. [ABSTRACT FROM AUTHOR]

Acute and subacute toxicity tests for chlorpyrifos and glyphosate were performed on the crayfish, Astacus leptodactylus. The crayfish were divided into a control group and four experimental groups with exposure from 50.18 to 301.11 μg L−1 of chlorpyrifos for 96 h under semi-static test conditions. In the same experiment, the crayfish were exposed to different concentrations of glyphosate (from 0.0, 8.14 to 13.05 mg L−1) for 96 h. Mortality was recorded, and the median lethal concentrations (LC 50) were calculated using probit analysis. The 96 h LC 50 values of chlorpyrifos and glyphosate to A. leptodactylus were 49.55 ± 4.66 μg L−1 and 7.83 ± 0.50 mg L−1, respectively. The results showed that chlorpyrifos was a few hundred times more toxic than glyphosate for the crayfish. Then, the crayfish were exposed to different subacute concentrations of chlorpyrifos (12.5 and 25 μg L−1) and glyphosate (2 mg L−1 and 4 mg L−1) for seven days, and their toxicity was evaluated through several hemolymph biochemical parameters. Chlorpyrifos and glyphosate exposure caused a significant (P < 0.01) increase in the activity of lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT). The results showed a significant (P < 0.01) decrease in acetylcholinesterase (AChE), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and phenoloxidase (PO) activities in the hemolymph of the crayfish exposed to chlorpyrifos and glyphosate. The total protein and cholesterol levels showed a significant decrease (P < 0.01) in the hemolymph of the crayfish after seven days of exposure to chlorpyrifos and glyphosate. There was a significant increase in triglycerides and glucose levels in treated crayfish. These results show that chlorpyrifos is highly toxic, while glyphosate is moderately toxic to A. leptodactylus. According to the results, subacute concentrations of chlorpyrifos and glyphosate could lead to a collapse of cellular homeostasis and changes in the hemolymph biochemical parameters in the crayfish. Physiological changes caused by exposure to chlorpyrifos and glyphosate in A. leptodactylus may have direct effects on the survival of these organisms. Unlabelled Image • The 96 h LC50 values of chlorpyrifos to A. leptodactylus were 49.55 ± 4.66 μg L−1 • The 96 h LC50 values of glyphosate to A. leptodactylus were 7.83 ± 0.50 mg L−1 • Chlorpyrifos and glyphosate decreased AST, ALT, ALP, AChE and PO activities in Crayfish • Chlorpyrifos and glyphosate increased GGT and LDH activities in Crayfish [ABSTRACT FROM AUTHOR]