Effects of sub-chronic exposure to terbutryn in common carp (Cyprinus carpio L.)

Neurotoxicity of Some Environmental Pollutants to Zebrafish

The aquatic environment encompasses a wide variety of pollutants, from plastics to drug residues, pesticides, food compounds, and other food by-products, and improper disposal of waste is the main cause of the accumulation of toxic substances in water. Monitoring, assessing, and attempting to control the effects of contaminants in the aquatic environment are necessary and essential to protect the environment and thus human and animal health, and the study of aquatic ecotoxicology has become topical. In this respect, zebrafish are used as model organisms to study the bioaccumulation, toxicity, and influence of environmental pollutants due to their structural, functional, and material advantages. There are many similarities between the metabolism and physiological structures of zebrafish and humans, and the nervous system structure, blood-brain barrier function, and social behavior of zebrafish are characteristics that make them an ideal animal model for studying neurotoxicity. The aim of the study was to highlight the neurotoxicity of nanoplastics, microplastics, fipronil, deltamethrin, and rotenone and to highlight the main behavioral, histological, and oxidative status changes produced in zebrafish exposed to them.

The Antioxidant and Hepatoprotective Potential of Berberine and Silymarin on Acetaminophen Induced Toxicity in Cyprinus carpio L

Berberine (BBR) and silymarin (SM) are natural compounds extracted from plants known for their antioxidant and chemoprotective effects on the liver. The present study aimed to investigate the beneficial properties of BBR and SM and the association of BBR with SM on liver function using fish as "in vivo" models. Moreover, the study investigated their hepatoprotective role after acetaminophen (APAP) exposure. For this purpose, the fish (N = 360; 118.4 ± 11.09 g) were fed with control or experimental diets for 9 weeks. In the experimental diets, the feed was supplemented with either SM (1 g/kg feed), BBR (100 and 200 mg/kg feed), or a combination of BBR with SM (SM 1 g/kg feed + BBR 100 mg/kg feed and, respectively, SM 1 g/kg feed + BBR 200 mg/kg feed). After the feeding trial, seven fish from each tank were randomly selected and exposed to a single APAP dose. The selected serum biochemical markers, oxidative stress markers, and lysozyme activity were used to evaluate the efficiency of the supplements on carp's health profile, particularly regarding the hepatopancreas function. Our results showed that the inclusion of SM and BBR (either as a single or in combination) reduced the serum contents of total cholesterol, triglyceride, and alanine transaminase. An increase in the high-density cholesterol was observed after the administration of BBR or BBR in association with SM. Both supplements showed hepatoprotective activity against APAP-induced hepatotoxicity, especially BBR. The ameliorative effects of SM (1 g) in association with BBR (100 mg) were highlighted by the modulation of the nonspecific immune system and oxidative stress alleviation after APAP exposure.

"Fishcide" effect of the fungicide difenoconazole in freshwater fish (Labeo rohita): A multi-endpoint approach

Difenoconazole is widely used to protect crops, fruits, and vegetables. However, this fungicide can enter aquatic environments and cause harmful effects to non-target organisms and induce little-known biological disorders. Thus, aiming to expand our knowledge about the ecotoxicity of difenoconazole on freshwater ichthyofauna, we aimed to determine the median lethal concentration (LC₅₀) of difenoconazole and evaluate its possible impacts from different toxicity biomarkers, using freshwater fish Labeo rohita as a model system. Using the probit analysis method, the 96 h LC₅₀ value of difenoconazole in the fish was calculated as 4.5 mg L^-1. Posteriorly, fish were exposed to two sublethal concentrations (0.45 mg L^-1 1/10th and 0.9 mg L^-1 1/5th LC₅₀ value) for 21 days. A significant reduction of superoxide dismutase (SOD) and catalase (CAT) activity was noted in the gill, liver, and kidneys of fish compared to the control groups. The level of glutathione-S-transferase (GST) and lipid peroxidation (LPO) activity was higher in all vital tissues of difenoconazole-treated fish. Histological alterations in the gill include epithelial lifting, lamellar fusion, hypertrophy, and epithelial necrosis. At the same time, the liver showed pyknotic nucleus, vacuolation, cellular edema and tubular necrosis, shrinkage of glomeruli, vacuolation, and pyknotic nuclei in the kidney. DNA damage was increased significantly with tail formation based on the concentration and time-dependent manner. Therefore, our study confirms that the exposure of L. rohita to difenoconazole induces negative biological consequences and sheds light on the danger of this fungicide for freshwater fish species. We believe that studies like ours can support actions and strategies for the remediation/mitigation of aquatic pollution by difenoconazole and for the conservation of freshwater ichthyofauna.

Blood biomarkers as diagnostic tools: An overview of climate-driven stress responses in fish

Global climate change due to anthropogenic activities affects the dynamics of aquatic communities by altering the adaptive capacities of their inhabitants. Analysis of blood provides valuable insights in the form of a comprehensive representation of the physiological and functional status of fish under various environmental and treatment conditions. This review synthesizes currently available information about blood biomarkers used in climate change induced stress responses in fish. Alterations in informative blood-based indicators are used to monitor the physiological fitness of individual fishes or entire populations. Specific characteristics of fish blood, such as serum and plasma metabolites, cell composition, cellular abnormalities, cellular and antioxidant enzymes necessitate adapted protocols, as well as careful attention to experimental designs and meticulous interpretation of patterns of data. Moreover, the sampling technique, transportation, type of culture system, acclimation procedure, and water quality must all be considered for valid interpretation of hemato-biochemical parameters. Besides, blood collection, handling, and storage time of blood samples can all have significant impacts on the results of a hematological analysis, so it is optimal to perform hemato-biochemical evaluations immediately after blood collection because long-term storage can alter the results of the analyses, at least in part as a result of storage-related degenerative changes that may occur. However, the scarcity of high-throughput sophisticated approaches makes fish blood examination studies promising for climate-driven stress responses in fish.

Neuro-hepatopathological changes in juvenile Oreochromis niloticus exposed to sublethal concentrations of commercial herbicides

The current study estimates the impact of different common herbicides on antioxidant defenses and histological structure of liver and spinal cord of juvenile tilapia. Eighty-four fish were divided into seven groups: group 1 fish acted as controls and the remaining fish were exposed to sublethal concentrations of acetochlor, bispyribac-sodium, bentazon, bensulfuron-methyl, halosulfuron-methyl, or quinclorac at sublethal concentrations 2.625, 0.800, 36.00, 2.50, 1.275, and 11.250 mg/l, respectively, for 96 h. Antioxidant parameters changed in response to some test herbicides and the greatest effects were caused by exposure to acetochlor and quinelorac for all antioxidant measurements. Prominent histological changes in liver tissue included loss of liver architecture and the appearance of fatty liver cells, necrotic areas, foci of leukocytic infiltration and many apoptotic cells. The most obvious changes in the spinal cord in all treated fish were degradation of myelinated white matter fibers with the emergence of empty spaces, large aggregation of pyknotic neuroglial nuclei, and damaged areas in the dorsal horn of gray matter. Collectively, the harmful effect of tested herbicides on antioxidant capacity and significant alterations in histological structures of liver and spinal cord of Oreochromis niloticus.

Environmental risk assessment of priority biocidal substances on Polish surface water sample

The EU directive 2013/39/EU has incorporated four biocidal compounds as priority substances: diuron, isoproturon, cybutryne, and terbutryn. The research was undertaken to determine the concentration of biocides in surface waters in three locations in southern Poland: the Wisła River in Kraków, the Wisłoka River in Mielec, and the drainage ditch draining water from arable fields located near Mielec. Environmental samples were taken in two series: winter (February) and spring (May and June). The analyses were carried out using gas chromatography with mass spectrometry. The seasonality of biocides in surface waters was observed. In winter samples, the concentrations were below MQL, while in spring, they ranged from a few to several dozen nanograms per liter. The highest concentrations of all analyzed compounds were recorded in water taken from the Wisła River. According to directive 2013/39/EU, the maximum allowable concentration was exceeded only in the case of cybutryne in water from the Wisła, both in May and in June. The assessment of the toxicity with the tested compounds was defined based on the Environmental Risk Assessment method. Low risk was estimated for diuron and isoproturon, while moderate risk for terbutryn and cybutryne.

Blood biomarkers of herbicide, insecticide, and fungicide toxicity to fish-a review

Pesticides are widely used in the world agriculture, and they may adversely affect non-target organisms, including fish. The present 2000-2019 literature review summarizes hematological and blood biochemical effects of various herbicides, insecticides, and fungicides in fish. The observed changes usually indicate anemia and inflammation, as well as hyperglycemia, hypoproteinemia, increase in cortisol concentration and activities of hepatic aminotransferases that are typical for intoxication and stress. Other changes that are also sometimes observed such as increase in red blood parameters indicate compensatory response. The often-noted symptoms of immunosuppression show an adverse effect of pesticides on immune system and possible immunosuppression. Pathophysiological changes in fish induced by pesticides depend on many factors, such as active compound and its concentration, exposure duration, fish species, environmental conditions, etc. Hematological and blood biochemical parameters appear to be useful biomarkers for evaluation of physiological state of fish exposed to pesticides; however, they are not specific markers of intoxication.

Antioxidant activities of Moringa oleifera leaf extract against pendimethalin-induced oxidative stress and genotoxicity in Nile tilapia, Oreochromis niloticus (L.)

To assess the ameliorative effects of Moringa oleifera (MO) leaf extract on haematological and biochemical changes, liver DNA damage and oxidative stress biomarkers in Nile tilapia (Oreochromis niloticus) exposed to a sublethal concentration (0.52 mg/l) of pendimethalin (PM). Tilapia fish were allocated into four equal groups in tri-replicates as follows: first group was the control group, second group was treated with MO (20 ml/30 l water), third group was exposed to 0.52 mg PM/l and fourth group was exposed to 0.52 mg PM/l and treated with MO leaf extract (20 ml/30 l water) for 28 days. At the end of this period, blood and liver tissue samples were collected and haematological and biochemical changes, hepatic DNA fragmentation and oxidative stress biomarkers were analysed. Pendimethalin caused significant reduction in haematological profile [White blood cells (WBCs) and red blood cells (RBCs) counts, haemoglobin (Hb) concentration and haematocrit (Ht) level]; meanwhile, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), creatinine, uric acid, glucose, cortisol, cholesterol and lactate dehydrogenase (LDH) were significantly increased. On the other hand, serum total protein, albumin, globulin and acetylcholinesterase (AChE) were decreased. Significant reduction in hepatic superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (TAC) and glutathione peroxidase (GSH-Px) levels and marked increments of hepatic malondialdehyde (MDA) and DNA fragmentation were observed in PM-exposed fish compared to the control group. The addition of Moringa oleifera leaf extract into the water could overcome the negative impacts of pendimethalin and normalise the examined parameters nearly to the control values. Moringa oleifera was used for the first time to protect tilapia fish against PM-induced toxicity. The present study revealed that Moringa oleifera has potent antioxidant and antigenotoxic actions against pendimethalin toxicity.

Exposure to herbicide linuron results in alterations in hematological profile and stress biomarkers of common carp (Cyprinus carpio)

Phenylurea herbicides such as linuron are commonly applied in agriculture. Common carp juveniles were subjected to 31.5 µg/L of linuron for 14 days, and then to 30 days of purification. Peripheral blood was sampled after 1, 3, 7 and 14 days of exposure and 7, 14 and 30 days of purification and hematological parameters were evaluated: erythrocyte (RBCc) and leukocyte (WBCc) counts, hematocrit (Ht), hemoglobin concentration (Hb), mean cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and differential leukocyte count. For evaluation of cortisol and catecholamine concentrations blood was sampled after 3, 6 and 12 h, after 1, 3 and 14 days of exposure, and after 30 days of purification. Linuron caused mainly transient increase in RBCc, Ht and MCV values and increase in WBCc and percentage of juvenile neutrophils. The herbicide caused persistant increase of cortisol and catecholamine concentrations. The results indicate that exposure to low concentration of linuron induced a stress response in common carp.

Direct and indirect effects of pesticides on a benthic grazer during its life cycle

BACKGROUND

Macroinvertebrates in aquatic ecosystems are repeatedly exposed to pesticides during their life cycle. Effects of consecutive exposure during different life stages and possible synergistic effects are not addressed in the standardized hazard assessment. The present study investigated two environmentally relevant exposure scenarios in batch (microcosm) and artificial indoor stream (mesocosm) experiments using the larvae of the mayfly Rhithrogena semicolorata (grazer) and natural aufwuchs. Grazers were analysed regarding growth, physiological condition, and drift behaviour, while the aufwuchs was analysed in terms of biomass using the particulate organic carbon as well as the chlorophyll a content. The aim was to reveal direct and indirect effects of an herbicide exposure during autumn on juvenile grazers and an insecticide exposure during spring on semi-juvenile grazers.

RESULTS

Direct and indirect effects were found in both exposure scenarios at environmentally relevant concentrations. In the herbicide exposure scenario with terbutryn, clear direct effects on the aufwuchs community with a LOEC of 0.38 µg L^-1 were found. Effect levels of grazers due to indirect effects were equal, with the overnight drift being the most sensitive grazer endpoint. In the insecticide exposure scenario, clear lethal and sub lethal effects of lambda-cyhalothrin were evident. Derived LC₅₀ values for the artificial indoor stream and batch experiment were 2.42 µg g^-1 OC (69 days) and 1.2 µg g^-1 OC (28 days), respectively. Sub lethal effects in terms of increased drift as well-reduced growth and triglyceride levels were found at concentrations of 1.4 and 0.09 µg g^-1 OC (LOECs). These results were confirmed by the batch experiment, which revealed effect values in the similar range. Finally, a clear indirect effect of the insecticide on the aufwuchs was evident in the batch experiment with an LOEC at 0.9 µg g^-1 OC.

CONCLUSION

Toxicity Exposure Ratios calculated with the derived effect values indicate a risk for the investigated grazer by both pesticides. Moreover, observed indirect effects during the herbicide exposure seem to be able to affect the grazers during a second exposure with an insecticide, due to reduced physiological conditions. We suggest further research with time-shifted exposure scenarios to gain a better understanding of the complex interactions of pesticides with the life cycle and the food webs of macroinvertebrates.

Monitoring and spatiotemporal variations of pyrethroid insecticides in surface water, sediment, and fish of the river Chenab Pakistan

There is a serious concern regarding freshwater resources of Pakistan which have been mismanaged and now are depleting extensively due to other reasons like intensive application of agricultural pesticides and insecticides. The present study was conducted to determine the concentrations of cypermethrin, deltamethrin, permethrin, and bifenthrin in the samples of water, sediments, and fish collected from various locations of River Chenab, Pakistan, during summer and winter seasons. These locations include namely Marala, Khanki, Qadirabad, and Trimu Headworks. High-performance liquid chromatography (HPLC) was deployed for analysis and determination of pyrethroid concentrations in these samples. The analytics show the order of pyrethroid concentrations in river as fish> sediment>water. Whereas maximum concentrations of 0.472 μg g^-1 found in fish and minimum concentrations were determined in water, i.e., 0.087 μg L^-1 at the sampling locations of Trimu and Marala headworks, respectively. Moreover, highest mean concentrations of pyrethroid, i.e., 1.248 μg g^-1 in fish were detected in winter season as compared to summers, i.e., 0.087 μg L^-1. However, all the values of pyrethroid were found to be lower than the maximum permissible levels specified by EU and WHO-FAO. Whereas the levels of deltamethrin and permethrin in water were found much higher than the specific limits set by EU.

Effect of thiacloprid on early life stages of common carp (Cyprinus carpio)

Toxicity of the neonicotinoid pesticide thiacloprid to embryos and larvae of common carp Cyprinus carpio was assessed under laboratory conditions. Carp embryos and larvae were exposed to thiacloprid at four concentrations: 4.5 (environmental concentration), 45, 225, and 450 μg/L for 35 days and compared to a non-treated control group. The effects on lipid peroxidation, antioxidant enzyme levels (superoxide dismutase, glutathione reductase, catalase, glutathione S-transferase, and reduced glutathione), mortality, growth, development, and histopathogenesis were assessed. Thiacloprid at tested concentrations were not associated with negative effects on hatching, behaviour, embryo viability, or Fulton's condition factor. Carp exposed to 45 μg/L thiacloprid showed lower weight and length compared to controls. Thiacloprid at 225 and 450 μg/L delayed development and led to lower weight and length of carp. Significantly lower superoxide dismutase and glutathione reductase activity was observed at all tested concentrations of thiacloprid compared with the control group. Chronic thiacloprid exposure of early-life stages of carp affected ontogeny and growth rate, and inhibited antioxidant capacity.

Effects of terbuthylazine-desethyl, a terbuthylazine degradation product, on red swamp crayfish (Procambarus clarkii)

Terbuthylazine is a widely used triazine pesticide. This, together with one of its degradation products, terbuthylazine-desethyl (TD), are frequently found in quantities exceeding the EU limit of 0.1μg/L in aquatic ecosystems where they might constitute a serious risk to non-target organisms. The sub-chronic effects of TD at 2.9μg/L (real environmental concentration) and at 580μg/L were investigated in a non-target aquatic species, the red swamp crayfish (Procambarus clarkii). Gill and hepatopancreas histopathology, alterations in biochemical parameters of haemolymph, oxidative damage to hepatopancreas, and changes in antioxidant biomarkers in muscle and hepatopancreas were recorded at both tested concentrations after 14days exposure. A 14day recovery period in TD-free water was not sufficient for restoration of normal parameters. Chronic terbuthylazine-desethyl exposure affected biochemical profile, and the antioxidant system, caused oxidative stress and histopathological changes in hepatopancreas of red swamp crayfish.

Effects of the terbuthylazine metabolite terbuthylazine-desethyl on common carp embryos and larvae

Toxicity of terbuthylazine-desethyl to embryos and larvae of common carp (Cyprinus carpio) was assessed. Based on mortality, the lethal concentration of terbuthylazine-desethyl was estimated to be 31days LC50=441.6μg/L. Carp exposed to terbuthylazine-desethyl at 1800μg/L exhibited lower weight and length at 7days of exposure compared to the control group. By day 20, carp exposed to 900μg/L terbuthylazine-desethyl showed lower weight and length compared to control group. Terbuthylazine-desethyl in concentrations (180, 900, and 1800μg/L) caused delay in ontogenetic development. Total superoxide dismutase activity was significantly lower in all exposed groups. Exposure to 180 and 900μg/L terbuthylazine-desethyl was associated with alteration of the caudal kidney tubular system including peritubular dilatation detachment of epithelial cells from the basal lamina, and focal autolytic disintegration of the tubular epithelia. Chronic terbuthylazine-desethyl exposure affected survival, growth, ontogenetic development, and the antioxidant system and caused pathological changes to the caudal kidney.

Hepatotoxicity of herbicide Sencor in goldfish may result from induction of mild oxidative stress

The effects of 96 h exposure to 7.14, 35.7, or 71.4 mg L(-1) of Sencor were studied on liver and plasma parameters in goldfish, Carassius auratus L. Goldfish exposure to 71.4 mg L(-1) of Sencor for 96 h resulted in a decrease in glucose concentrations in plasma and liver by 55%, but did not affect liver glycogen levels. An increase in the activity of aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase (by 24-27%, 32-72%, and 87-102%, respectively) occurred in plasma of Sencor exposed goldfish, whereas in liver activities of these enzymes decreased (by 15-17%, 19%, and 20%, respectively). Lactate concentration in plasma increased by 22-36% in all treated fish groups, whereas in liver it increased by 64% only after exposure to 35.7 mg L(-1) of Sencor. Herbicide exposure enhanced lipid peroxide levels by 49-75% and decreased activities of catalase by 46%, glutathione reductase by 25-48% and glutathione peroxidase by 21-26% suggesting development of oxidative stress in liver. The treatment induced various histological changes in goldfish liver, such as dilated sinusoids, hypertrophy and dystrophy of hepatic cells and detachment of endothelial cytoplasm with diffuse hemorrhage. The data collectively let us propose that mild oxidative stress might be responsible for the hepatotoxicity of Sencor.

Effects of prometryne on early life stages of common carp (Cyprinus carpio L.)

Toxicity of prometryne to early life stages of common carp was assessed. On the basis of accumulated mortality in the experimental groups lowest observed-effect concentration (LOEC) was estimated as 1100 µg/l; and no observed-effect concentration (NOEC) was 850 µg/l. Fulton's condition factor was significantly lower than in controls in fish exposed to 4000 µg/l after 7, 14, and 21 days. By day 14, fish exposed to 4000 µg/l prometryne showed significantly lower mass and total length compared to controls. Fish exposed the 1200 and 4000 µg/l showed delay in development, severe hyperaemia in gill, liver, and caudal and cranial kidney. Subchronic prometryne exposure of early-life stages of common carp at concentrations of 1200 and 4000 µg/l affected their survival, growth rate, early ontogeny, and histology.

Chlorinated herbicides in fish, birds and mammals in the Baltic Sea

The aim of the present work was to determine the concentration levels, as well as accumulation and magnification coefficients, of triazine derivatives in herring gulls and Baltic grey seals 11 years after a ban on their use in the EU and eight after their exclusion in Poland. Dead birds were collected in the coastal zone of the Gulf of Gdansk in the years 2010-2012. The grey seals, on the other hand, were from before 2007, when s-triazine derivatives were still in use. Triazine herbicides (atrazine, simazine, propazine, terbutrine, prometrone, prometrine and ametrine) were found in the muscles and livers of birds and mammals and also in fish. The obtained results indicated the presence of all the assayed triazines in whole Baltic herring and their livers, while fish muscles were found to be free of prometrone and ametrine. In the muscles and liver of the grey seal, no ametrine, propazine or terbutrine were found, while prometrine was found in the liver of only one specimen. Research showed that simazine did not accumulate and magnify in marine birds and mammals. Atrazine became accumulated in the liver of birds and mammals while magnification was determined in their muscles. The accumulation of ametrine was found in the muscles of seals.

The sub-lethal effects and tissue concentration of the human pharmaceutical atenolol in rainbow trout (Oncorhynchus mykiss)

Atenolol is a highly prescribed anti-hypertensive pharmaceutical and a member of the group of β-blockers. It has been detected at concentrations ranging from ng L(-1) to low μg L(-1) in waste and surface waters. The present study aimed to assess the sub-lethal effects of atenolol on rainbow trout (Oncorhynchus mykiss) and to determine its tissue-specific bioconcentration. Juvenile rainbow trout were exposed for 21 and 42 days to three concentration levels of atenolol (1 μg L(-1) - environmentally relevant concentration, 10 μg L(-1), and 1000 μg L(-1)). The fish exposed to 1 μg L(-1) atenolol exhibited a higher lactate content in the blood plasma and a reduced haemoglobin content compared with the control. The results show that exposure to atenolol at concentrations greater than or equal to 10 μg L(-1) significantly reduces both the haematocrit value and the glucose concentration in the blood plasma. The activities of the studied antioxidant enzymes (catalase and superoxide dismutase) were not significantly affected by atenolol exposure, and only the highest tested concentration of atenolol significantly reduced the activity of glutathione reductase. The activities of selected CYP450 enzymes were not affected by atenolol exposure. The histological changes indicate that atenolol has an effect on the vascular system, as evidenced by the observed liver congestion and changes in the pericardium and myocardium. Atenolol was found to have a very low bioconcentration factor (the highest value found was 0.27). The bioconcentration levels followed the order liver>kidney>muscle. The concentration of atenolol in the blood plasma was below the limit of quantification (2.0 ng g(-1)). The bioconcentration factors and the activities of selected CYP450 enzymes suggest that atenolol is not metabolised in the liver and may be excreted unchanged.

Effect of terbuthylazine-2-hydroxy at environmental concentrations on early life stages of common carp (Cyprinus carpio L.)

The aim of the study was to investigate effects of the triazine's herbicide terbuthylazine-2-hydroxy on early life stage of common carp (Cyprinus carpio L.) through antioxidant indices, mortality, growth, development, and histopathology. Based on accumulated mortality in the experimental groups, lethal concentrations of terbuthylazine-2-hydroxy were estimated at 35-day LC50 = 10.9 mg/L terbuthylazine-2-hydroxy. By day 15, fish were exposed to 3.5 mg/L and by day 26, fish were exposed to 0.0029 mg/L; real environmental concentration in Czech rivers, 0.07 mg/L, 1.4 mg/L, and 3.5 mg/L terbuthylazine-2-hydroxy, showed significantly lower mass and total length compared with controls. Based on inhibition of growth in the experimental groups, lowest observed effect concentration (LOEC) = 0.002 mg/L terbuthylazine-2-hydroxy and no observed effect concentration (NOEC) = 0.0001 mg/L terbuthylazine-2-hydroxy. No significant negative effects on hatching or embryo viability were demonstrated at the concentrations tested, but significant differences in early ontogeny among groups were noted. Fish from the two highest tested concentrations showed a dose-related delay in development compared with the controls. Total superoxide dismutase (SOD) activity was significant lower in all groups testedly for terbuthylazine-2-hydroxy compared with the control group. At concentrations of 1.4 and 3.5 mg/L damage to caudal kidney tubules when compared to control fish was found.

Short and long-term effects of clofibric acid and diclofenac on certain biochemical and ionoregulatory responses in an Indian major carp, Cirrhinus mrigala

Extensive use of pharmaceuticals in human and veterinary medicine and aquaculture practices pose a serious threat to aquatic organisms. In the present investigation, Cirrhinus mrigala an Indian major carp was exposed to different concentrations of clofibric acid (CA) and diclofenac (DCF) and certain biochemical and ionoregulatory responses were assessed under short and long term exposures. During short-term (96h) exposure period, plasma glucose and sodium (Na(+)) levels were increased at all concentrations (1, 10 and 100μgL(-1)) of CA and DCF treated fish. Plasma protein and chloride (Cl(-)) levels were found to be decreased at all concentrations of CA and DCF exposed fish comparatively to control groups. Meanwhile an increase in plasma potassium (K(+)) level was noted in fish exposed to CA treatments alone and in DCF treatments it was decreased. In long-term exposure (35d), plasma Na(+) and Cl(-) levels were found to be significantly increased at all concentration of CA and DCF. However, a biphasic trend was observed in plasma glucose, protein and K(+) levels. In both the treatments, a significant (P<0.01 and P<0.05) changes were observed in all parameters measured in fish exposed to different concentrations of CA and DCF. The results of the present investigation indicate that both the drugs caused significant changes in biochemical and ionoregulatory responses of fish at all concentrations. The alterations of these parameters can be useful in monitoring of pharmaceutical residues present in aquatic environment.

The effects of subchronic exposure to metribuzin on Danio rerio

The aim of this study was to assess the impact of metribuzin in surface waters on fish under experimental conditions. The effects of subchronic exposure to metribuzin on fish growth and the development of histopathological changes in selected organs (gill, kidney, liver) and on activity of some biochemical markers (CYP450, EROD) in Danio rerio were investigated during a 28-day toxicity test. Juvenile growth tests were performed on D. rerio according to OECD method number 215. Fish at an initial age of 30 days were exposed to a range of metribuzin concentrations (1.5, 5, 16, 33, and 53 mg L⁻¹). Exposure to metribuzin at 53 mg L⁻¹ was associated with increased mortality. Negative effects with regard to total body weight, length, and the inhibition of specific growth rate were induced at concentrations of 33 and 53 mg L⁻¹. Histopathological examination revealed pathological lesions in the liver in pesticide-exposed fish only at the highest concentration of 53 mg L⁻¹ of metribuzin. Based on the results of growth rate, biochemical markers (CYP450, EROD), and histopathological examination, the lowest observed effect concentration (LOEC) value was 33 mg L⁻¹ and the no observed effect concentration (NOEC) value was 16 mg L⁻¹.

The effects of subchronic exposure to terbuthylazine on early developmental stages of common carp

The aim of this study was to assess the impact of terbuthylazine in surface waters on fish under experimental conditions. Subchronic toxic effects on embryos and larvae of common carp (Cyprinus carpio) were investigated during a 30-day toxicity test. The exposure to terbuthylazin showed no effect on mortality, but significant differences (P < 0.0001) were revealed on weight and growth parameters at concentrations of 520 and 820 μg/L. The inhibition of specific growth rate at concentrations of 520 and 820 μg/L was 14% compared to the control group. No significant negative effects on total body length and body weight were observed at lower concentrations (0.9 and 160 μg/L). The concentrations 520 and 820 μg/L were associated with a delay in development compared to other experimental groups and controls. On the basis of weight and growth rate evaluation and determination of developmental stages, the No Observed Effect Concentration (NOEC) of terbuthylazine was estimated at 160 μg/L and the Lowest Observed Effect Concentration (LOEC) was 520 μg/L. According to these results, the reported environmental concentration of terbuthylazine in Czech rivers does not impact growth, development, morphology, or histology of carp embryos and larvae.

Effects of long-term exposure to simazine in real concentrations on common carp (Cyprinus carpio L.)

The effects of a 90 day simazine exposure at concentrations of 0.06 (reported concentration in Czech rivers), 1, 2, and 4 μg L⁻¹ were assessed in one-year-old common carp (Cyprinus carpio L.). Its influence on biometric parameters, hematology, blood biochemistry, liver biomarkers, and histology was investigated. Biometric parameters of common carp exposed to simazine at 0.06 μg L⁻¹ showed no differences from untreated fish. Simazine concentrations of 1, 2, and 4 μg L⁻¹ caused significant (p<0.01) increase of hepatosomatic indices relative to controls. Hematological profiles showed significant (p<0.01) decrease in leukocyte count relative to controls at all concentrations. Biochemical profiles of common carp exposed to simazine at all concentrations showed significant (p<0.01) increase in activity of alkaline phosphatase. In addition, at concentrations of 1 and 2 μg L⁻¹, there was a significant increase in alanine aminotransferase (p<0.05), and, at 4 μg L⁻¹, a significant increase in total protein (p<0.05), albumins (p<0.05), and alanine aminotransferase (p<0.05) compared with controls. Renal histology revealed severe hyaline degeneration of the epithelial cells of caudal kidney tubules in fish at all exposure levels compared to controls. Chronic exposure of common carp to simazine caused significant shifts in hematological, biochemical, and biometric profiles, and histopathological changes. The results of this study indicate that chronic exposure of simazine has altered multiple physiological indices in fish hematology and biochemistry, which potentially may be a biomarker of simazine toxicity; however, before these parameters are used as special biomarkers for monitoring residual simazine in aquatic environment, more detailed experiments in laboratory need to be performed in the future.