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Microplastics pollution and salinity intrusion in freshwater ecosystem is one of the worldwide climate change consequences those have negative impacts on the physiology of aquatic organisms. Hence, a 15-day experiment was carried out where Nile tilapia (Oreochromis niloticus) was exposed to different salinity gradients i.e. 0 ‰, 3 ‰, 6 ‰, 9 ‰, and 12 ‰ alone and along with 10 mg/L polyamide microplastics (PA-MP) in order to measure its effects on the hematology, gill, and intestinal morphology. The results exhibited that all the fish treated with PA-MP ingested microplastics and the quantity of accumulation was significantly greater in higher salinity gradients (9 ‰ and 12 ‰). In addition, the PA-MP treated fish showed increased glucose level and at the same time reduced hemoglobin concentration with the increase of salinity. The percentages of abnormalities in erythrocytes both cellular (twin, teardrop and spindle shaped) and nuclear (notched nuclei, nuclear bridge and karyopyknosis) significantly enhanced with PA-MP exposure again in higher salinity treatments (9 ‰ and 12 ‰). The principal component analysis (PCA) exhibited that the addition of 10 mg/L PA-MP negatively affected the hematology of Nile tilapia than that of salinity treatments alone. Besides, the exposure of PA-MP in 9 ‰ and 12 ‰ salinity gradients escalated the severity of histological damages in gills and intestine. Overall, this experiment affirms that the increase of salinity enhanced the microplastics ingestion and toxicity in Nile tilapia, therefore, PA-MP possibly is addressed as additional physiological stressors along with increased salinity gradients in environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Early cyanobacterial blooms studies observed that exposure to blue-green algae led to fish gills impairment. The objective of this work was to evaluate the toxic mechanisms of exudates of Microcystis aeruginosa (MaE) on fish gills. In this study, the toxic mechanism of MaE (2×10 6 cells/mL) and one of its main components phytosphingosine (PHS) with two concentrations 2.9 ng/mL and 145 ng/mL were conducted by integrating histopathology, biochemical biomarkers, and transcriptomics techniques in Sinocyclocheilus grahami (S. grahami) for 96 h exposure. Damaged gill tissue with epithelial hyperplasia and hypertrophy, remarkable Na + /K + -ATPase (NKA) enzyme activity, disrupted the redox homeostats including lipid peroxidation and inflammatory responses were observed in the fish of MaE exposure group. Compare to MaE exposure, two concentrations of PHS exposure appeared to be a trend of lower degree of tissue damage, NKA activity and oxidative stress, but induced obviously lipid metabolism disorder with higher triglycerides, total cholesterol and total bile acid, which might be responsible for inflammation responses in fish gill. By transcriptome analysis, MaE exposure were primarily enriched in pathways related to gill function and immune response. PHS exposure, with higher number of differentially expressed genes (DEGs), were enriched in Toll-like receptor (TLR), Mitogen-Activated Protein Kinase (MAPK) and NOD-like receptor protein 3 (NLRP3) pathways. We concluded that MaE and PHS were induced the inflammatory responses, with oxidative stress-induced inflammation for MaE exposure but lipid metabolism disorder-induced inflammation for PHS exposure. The present study provided two toxin-induced gill inflammation response pathways under cyanobacterial blooms, which could be a scientific basis for the ecological and health risk assessment in the aquatic environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

In aquaculture, fish are stressed with several factors involved in impacting the growth rate and health status. Although Nile tilapia can resist brackish water conditions, hypoxia status may impair the health condition of fish. Nile tilapia were exposed to salinity water at 0, 10, and 20‰ for four weeks then the growth behavior was checked. The results showed meaningfully lowered growth rate, feed utilization, and survival rate when fish kept in 20‰ for four weeks. Then fish were subdivided into six groups (factorial design, 2 × 3) in normoxia (DO, 6 mg/L) and hypoxia (DO, 1 mg/L) conditions for 24 h. High salinity (10 and 20‰) combined with hypoxia stress-induced inflammatory features in the intestines, gills, and livers of fish. The activities of SOD, CAT, and GPX were increased in the intestines, gills, and livers of fish grown in 10 and 20‰ and exposed with hypoxia stress. Fish grown in 20‰ and stressed with hypoxia had the highest ALT, AST, and ALP levels (p < 0.05) among the groups. The highest transcription levels of Il-8, Il-1β, Ifn-γ, Tnf-α, and Caspase-3 genes and the lowest level of Il-10 gene were observed in fish exposed with 20‰ and hypoxia. The outputs of Integrated Biomarker Response (IBR) showed marked differences between fish groups with varied values. The lowest IBR was observed in fish reared in fresh water and normoxia, while the highest IBR was seen in the group of fish reared in 20‰ and hypoxia conditions (p < 0.05). These results confirm that Nile tilapia can tolerate 10‰ in normoxia but 20‰ salinity combined with hypoxia results in oxidative stress, apoptosis, and inflammatory features in the intestines, gills, and livers. The obtained results indicate that hypoxia can affect the performances of Nile tilapia reared in brackish or high-water salinity leading to severe economic loss. Further future studies are required to understand the impact of different water salinities with hypoxia in the short term and long-term periods on the productivity of Nile tilapia., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Nitrate (NO 3 - ), a potential toxic nitrogenous compound to aquatic animals, is distributed in aquatic ecosystems worldwide. The aim of this study was to investigate the effects of different NO 3 - levels on growth performance, health status, and endocrine function of juvenile turbot (Scophthalmus maximus) in recirculating aquaculture systems (RAS). Fish were exposed to 0 mg/L (control, CK), 50 mg/L (low nitrate, LN), 200 mg/L (medium nitrate, MN), and 400 mg/L (high nitrate, HN) NO 3 -N for 60 d in experimental RAS. Cumulative survival (CS) was significantly decreased with increasing NO 3 - levels in LN, MN, and HN. The lowest CS was 35% in the HN group. Growth parameters, including absolute growth rate, specific growth rate, and feed conversion rate, were significantly different in HN compared with that in the CK. Histological survey of gills and liver revealed dose-dependent histopathological damage induced by NO 3 - exposure and significant differences in glutamate pyruvate transaminase and glutamate oxalate transaminase in MN and HN compared with that in the CK. The hepatosomatic index in HN was significantly higher than that in the CK. Additionally, NO 3 - significantly increased bioaccumulation in plasma in LN, MN, and HN compared to that in the CK. Significant decreases in hemoglobin and increases in methemoglobin levels indicated reduced oxygen-carrying capacity in HN. Additionally, qRT-PCR and enzyme-linked immunosorbent assay (ELISA) were developed to investigate key biomarkers involved in the GH/IGF-1, HPT, and HPI axes. Compared with that in the CK, the abundance of GH, GHRb, and IGF-1 was significantly lower in HN, whereas GHRa did not differ between treatments. The plasma T 3 level significantly decreased in LN, MN, and HN and T 4 significantly decreased in HN. The CRH, ACTH, and plasma cortisol levels were significantly upregulated in HN compared with that in the CK. We conclude that elevated NO 3 - exposure leads to growth retardation, impaired health status, and endocrine disorders in turbot and the NO 3 - level for juvenile turbot culture should not exceed 50 mg/L NO 3 -N in RAS. Our findings indicate that endocrine dysfunction of the GH/IGF-1, HPT, and HPI axes might be responsible for growth inhibition induced by NO 3 - exposure., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

The effects of chloridazon (Ch) and its metabolite chloridazon-desphenyl (Ch-D) at the environmentally relevant concentrations of 0.45 µg/L and 2.7 µg/L on signal crayfish Pacifastacus leniusculus were assessed in a 30-day exposure followed by a 15-day depuration period. Locomotion, biochemical haemolymph profile, oxidative and antioxidant parameters, and histopathology were evaluated. Crayfish exposed to Ch at 0.45 µg/L and 2.7 µg/L showed significantly (p < 0.01) higher CAT activity and GSH level in hepatopancreas and gill compared to controls. The concentration of Ch at 2.7 µg/L was associated with significantly (p < 0.01) higher levels of GLU, LACT, ALT, AST in haemolymph compared to controls. Chloridazon-desphenyl exposure at both tested concentrations caused significantly higher (p < 0.01) GLU, LACT, ALT, AST, NH 3 , and Ca in haemolymph; lipid peroxidation (TBARS) levels in hepatopancreas; and CAT activity and GSH level in hepatopancreas and gill. Alterations of structure including focal dilatation of tubules, increased number of fibrillar cells, and haemocyte infiltration in the interstitium were observed with 2.7 µg/L Ch and with both Ch-D exposures. Locomotion patterns did not vary significantly among groups. A 15-day recovery period was insufficient to restore normal physiological parameters in exposed groups. Chloridazon and its metabolite Ch-D exerts harmful effects on crayfish., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

The increase in pesticide use in response to agricultural demands poses a risk to non-target organisms, including fish. Integrated analysis of biochemical, histopathological and genetic parameters in fish exposed to Malathion insecticide provide information on the toxicity mechanisms of this pesticide, which is classified as a probable carcinogen for humans. The present study assessed the biological responses of Colossoma macropomum after exposure to Malathion. We started determining the lethal concentration, which is the concentration capable of killing 50% of the subjects in an acute toxicity test (LC 50 -96 h), which was 15.77 ± 3.30 mgL -1 . The fish were, then, exposed to Malathion during 96 h at a sublethal concentration, 7.30 mgL -1 . Overall, we observed an increased activity of biotransformation and antioxidant enzymes, which reduced production of mitochondrial reactive oxygen species after 96 h exposure, as well as kept constant the mitochondrial respiration, Acetylcholinesterase activity and DNA damage. However, fish exposed to insecticide presented severe gill histopathological damage and increased expression of proto-oncogene ras. Taken together, the results suggest that, after four days of exposure to the Malathion, C. macropomum efficiently activates its defense mechanisms, suggesting that the basal response mechanisms are responsive. On the other hand, histopathologic damages evidenced the adverse effects of Malathion on fish, since it promoted gill necrosis and increased the expression of ras oncogene that is directly related to tumorigenesis events., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Gill, as the organ of fish to contact most directly with xenobiotics, suffered more threat. To evaluate the impact of arsenite (AsIII) on the gill of fish, we measured the antioxidative responses (superoxide dismutase (SOD) and catalase (CAT) activities) and oxidative damage (malondialdehyde (MDA) content), histological changes and mRNA transcriptional responses of zebrafish gill, after exposure to AsIII (0, 10, 50, 100, and 150 μg L -1 ) solutions for 28 days. We found that AsIII increased the activities of CAT by 46%-87%, decreased the activities of SOD and the contents of MDA by 19% and 21%-32%. Furthermore, CuZnSOD and MnSOD mRNA transcription levels were also inhibited, decreasing by 62%-82% and 70%-77%. Besides, ≥ 100 μg L -1 AsIII also caused histological changes (a loss of mucus and desquamation in the surface of the epithelial cells) on zebrafish gill. These results showed that low concentrations of AsIII influenced biochemical and physiological performances of fish gill, which probably aggravates the toxic effect of AsIII on fish., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

An increasing concern for Gemini surfactants (GS) based on the class alkanediyl-α-ω-bis (dimethylalkylammonium bromide) has been reported in ecotoxicological researchbecause of their estrogenic properties causing an alarm to aquatic life. In this study, we analyzed the toxic effects of the synthesized GS (12-2-12 and 16-2-16) leading to histological changes in fingerlings (kidney, gills, intestine, and liver) of Cirrhinusmrigala. Damage in the tissues in correlation with their normal architecture was observed microscopically and was manifold. The tissue-specific morphological alterations associated with somatic index (MAV- mean alteration value) were used as biomarker. The present study also highlighted the changes in the antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT). In order to estimate the sub-lethal toxic properties of GS, the genotoxicity and cytotoxicity of GS were evaluated using blood smear assay and HeLa cell line respectively. Results of the study exhibited potential biotoxicity where GS with the highest hydrophobicity showed upper most toxicity level under different exposure time, while GS with less hydrophobic features exhibited least stressful regimeto the tested animal. The prepared GS were also examined for their biodegradability following the die-away method. The theoretical approach estimates the structural information by computational simulation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Pharmaceuticals are found in the aquatic compartment due to their continuous release in wastewater effluents or direct dispersal in aquaculture practices raising serious threats to human and environmental health. Erythromycin (ERY) is a macrolide antibiotic widely prescribed in human and veterinary medicine to threat a number of bacterial infections, being consequently found in the aquatic environment. The present work intends to evaluate the sub-lethal effects of ERY on juveniles of rainbow trout (Oncorhynchus mykiss) in terms of tissue damage using histochemical staining procedures. Individuals were exposed for 96 h (acute exposure: 0.001-10 mg/L) and 28 days (chronic exposure: 0.05-0.8 μg/L) to environmentally realistic concentrations of ERY. Qualitative and quantitative approaches were used to assess O. mykiss gills and liver tissue alterations after exposure to ERY. For both exposures the most common gill changes recorded were progressive (e.g. hypertrophy of mucous cells and hyperplasia of the epithelial cells). However, circulatory (e.g. aneurysms and oedemas) and regressive (e.g. epithelial lifting of lamellae and lamellar fusion) changes were also observed in the acute assay. Gill morphometric analysis revealed to be a good indicator of subtle alterations in gill architecture in agreement with the qualitative scoring system. In liver, regressive (e.g. cytoplasmic vacuolization, pyknotic nucleus and hepatocellular degeneration) and circulatory disturbances (e.g. hemorrhage and increase of sinusoidal space) were the most frequently observed alterations, but only for the acute assay. Furthermore, all histological changes observed contributed to a significant increase in the pathological index for both organs. The current data demonstrate the existence of a direct dose-effect relationship between the exposure to this specific macrolide antibiotic and the histological disorders recorded in different tissues of the exposed fish. The histopathological findings observed in this study may have been the result of several physio-metabolic dysfunctions. However, the observed tissue lesions were of minimal or moderate pathological importance, non-specific and reversible. Further investigation into the cellular mechanism of action of ERY is needed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

In human-altered rivers, fish are often conjointly exposed to an increase in water temperature due to global warming and to a contamination by organic pollutants such as pesticides, but their combined effects are still elusive. Thermal and chemical stressors could potentially interact because high temperature increases metabolism and toxicant uptake, and can alter the ability of organisms to set up adequate stress responses and to maintain homeostasis. These combined stressors could thus potentially result in higher level of molecular and cellular damage, and stronger effects on behavior and physiology, but experimental evidence across biological levels is still scarce. In this study, goldfish Carassius auratus were experimentally exposed to an environmentally realistic cocktail of pesticides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin and tebuconazol) commonly found in rivers of South-West of France at low or high dose in two different thermal conditions: a common summer temperature (22 °C) or a high temperature recorded during heat waves (32 °C). Results showed that high temperature alone caused behavioral and physiological changes (increased swimming activity, increased hepatosomatic index, decreased reproductive index) but limited cellular damage. However, high temperature aggravated the effects of pesticides at the molecular and cellular level. Indeed, pesticide exposure resulted in higher genotoxic effects (micronuclei rate) and irreversible cellular damage of the gills and liver (apoptosis, inflammation, necrosis) at 32 °C compared to 22 °C. This suggests potential synergistic effects of climate change and pollution, and highlights the need for multiple stress approaches to better predict the impacts of human activities on aquatic wildlife., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Iron is an essential element for many physiological functions of several organisms but in excess it causes toxicity. High iron content in water bodies of mountainous states is considered as one of the major factor, responsible for low productivity in aquaculture systems. But, till date comprehensive reports on the adverse effect of iron overload in aquatic organisms, especially cultured fishes are scanty. Therefore, the present study was undertaken to investigate the adverse effects of iron overload in economically important aquaculture fish species Labeo rohita. Three sub-lethal test concentration of iron (ferrous) viz., 1/16th, 1/8th and 1/4th of LC 50 (post 96 h) i.e. 8.25, 16.51 and 33.01 mg L -1 , respectively, were used for in vivo exposure. Blood cells and tissue samples of the control & exposed specimens were sampled at intervals of 24, 48, 72 and 96 h to assess alterations in hematological, oxidative stress and histological parameters. Significant changes in erythrocyte and leukocyte counts, hemoglobin, lipid peroxidation, antioxidant enzyme activity (super oxide dismutase and catalase) and tissue iron accumulation were observed in the exposed fish. Significant increase in lipid peroxidation, coupled with significant reduction in free radicals scavengers like super oxide dismutase and catalase revealed a compromised anti-oxidative defense mechanism in the fishes exposed to iron overload. Histological examination of gills and liver showed severe tissue injury and histological alternations. Severity was found to increase in time and concentration dependent manner. Perl's staining revealed accumulation of excess iron in liver of the exposed fish. The observed patho-physiological changes in the present study provide the most comprehensive insight of iron overload stress in L. rohita., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The recent discovery of illicit drugs in the aquatic environment has raised concerns about the possible effects on the aquatic fauna, because of the pharmacological activity of these substances. Cocaine is an illicit drug widespread in surface waters since it is the third most widely used drug in North America, Western and Central Europe, and the second in Latin America and the Caribbean. The aim of this study was to evaluate the influence of environmental concentrations of cocaine on the gills of the European eel (Anguilla anguilla). The gills of male silver eels exposed to 20 ng L -1 of cocaine for fifty days were compared to control, vehicle control and post-exposure recovery ten days groups. The following parameters were evaluated: the thickness of the interlamellar epithelium (TIE), the length of the secondary lamellae (LSL) and the fraction of the interlamellar epithelium and the secondary lamellae occupied by the mucous cells (MC(IE-SL)FA) 3) the plasma cortisol and prolactin levels. After cocaine exposure, the gill epithelium appeared hyperplastic. The following changes were observed: proliferation in the interlamellar epithelium; partial and total fusion of the secondary lamellae, that appeared shortened and dilated; epithelial lifting and aneurism in the secondary lamellae. Moreover, in cocaine exposed eels, an increase in TIE and MC(IE-SL)FA and a decrease in LSL were observed. These changes were still present ten days after the interruption of cocaine exposure. Plasma levels of both cortisol and prolactin increased after cocaine exposure; ten days after the interruption of cocaine exposure, the plasma cortisol levels were still higher, whereas the plasma prolactin levels were lower, than control values. Our results show that even a chronic exposure to low environmental cocaine concentrations severely harms the eel gills, suggesting damages to their functions, and potentially affecting the survival of this species., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Sugarcane vinasse is a residue generated at a rate fifteen times greater than the ethanol production. Because of its high organic and micronutrient content, this residue is used as a fertilizer on sugarcane crops. However, when used in large quantities, vinasse can saturate the soil and contaminate nearby water resources by percolation and leaching. Given the proven toxic potential of in natura vinasse, the present study aimed to evaluate the toxic potential of leached sugarcane vinasse using Nile tilapia (Oreochromis niloticus) as a test organism. A bioassay was performed after vinasse percolation in laboratory soil columns. The bioassay included one control group containing fresh water and two treatment groups, the first exposed to a 2,5% dilution of leached of vinasse and the second to a 2,5% dilution of in natura vinasse. After exposure, histopathological analysis was performed in gills and livers, and the latter were labelled for HSP70 proteins. No significant changes were detected in the gills of the exposed fish. However, in the liver, both in natura and leached vinasse induced statistically significant histopathological changes. These changes include hydropic degeneration, cell boundary losses, pyknotic nuclei and cellular disorganization. HSP70 expression significant increase in liver of both treatment groups were observed, being higher for the in natura vinasse exposed group. Results suggested that both leached vinasse and in natura vinasse were toxic, its still able to provoke histological changes and induce the cytoprotective response in exposed fish liver, evidenced by a immunostaining of cellular stress proteins. Thus, in order to reduce its environmental impact, appropriated effluent disposal is essential., (Copyright © 2018. Published by Elsevier Inc.)

Chub (Squalius cephalus) specimens were collected in Korenita River seven months after spillover from the waste water of antimony mine tailing pond and compared with chub living in Kruščica reservoir (intended for water supply) and Međuvršje reservoir (influenced by intense emission of industrial, urban and rural wastewater). Concentrations of 15 elements (Al, As, B, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Si, Sr, Zn) were determined in muscle, liver and gills of chub by inductively coupled plasma optical spectrometry (ICP-OES) and histopathological alterations in liver and gills were assessed. Chub specimens from Korenita River had higher concentrations of As, Ba and Pb in all three investigated tissues as well as higher total histopathological index values than chub from reservoirs. Specimens from Međuvršje reservoir were characterized by higher values for concentrations of Cu and Si in muscle tissue and higher values for regressive histopathological alterations in gills. Individuals of chub from Kruščica reservoir had the highest concentrations of Fe in liver, Hg in muscle and Sr and Zn in muscle while gills had the lowest value of total histopathological index. The results from the present study showed higher level of histopathological alterations as a result of mine tailing accident. As a result of mixed contamination on the Međuvršje site, histopathological index values of gills were in line with the index value from Korenita River. Increased values for Fe and Sr in chub tissue from Kruščica reservoir could be explained by geological structure of the site which is characterized by magmatic rock rich in Cu, Fe and Ni as well as dominant carbonate sediment complex of marine origin with increased level of Sr., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are lipophilic compounds able to accumulate in the food chain. Mussels showed to bioaccumulate contaminants, such as PAHs, so that recurrent consumption of such contaminated food represents a risk for human health. This study was aimed to elucidate if acute exposure of Mediterranean blue mussel (Mytilus galloprovincialis), a bivalve of great economic importance in several countries, to a PAH, benzo[a]pyrene (B[a]P), at doses able to induce cytochrome P450 1A (CYP1A) and pathological changes in mussel gills, can produce accumulation in soft tissue. We explored the cytotoxic effects (cell viability, DNA laddering, and glutathione levels) of in vitro exposure of human peripheral blood mononuclear cells (PBMCs) to organic extracts obtained from blue mussels previously exposed for 12 and 72h via water to B[a]P (0.5-1mg/L). In our experimental conditions, B[a]P induced CYP1A induction and morphological changes in mussel gills and a significant B[a]P accumulation in soft tissue. Conversely, exposing PBMCs to organic extracts obtained from contaminated mussels, resulted in a significant reduction of cell viability and cell glutathione content, and in an increase in DNA laddering. This confirms that consumption of mussels from B[a]P polluted waters might affect human health. Our data lead us to suggest that CYP1A activity in mussel gills may be useful (more than the amount of detected PAHs in the mussel edible tissue) as a marker in assessment of risk for health of consumers exposed to PAHs through ingestion of shellfish., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Bioassay tests on fingerlings (3.0 ± 0.5cm) of euryhyaline fish Lates calcarifer were conducted using customized continuous flow through system and derived 96h acute toxicity value for chlorpyrifos (CPF). Based on the measured concentration of CPF mean median lethal concentration (LC 50 ) of 1.07µg/l with lower and upper 95% confidence limits (0.95 and 1.19µg/l). No observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values were found to be 0.4, 0.09 and 0.07µg/l respectively. Key biomarker enzyme activities such as esterase, superoxide dismutase and malate dehydrogenase were measured in whole body tissues of the fish fingerlings on exposure to sublethal toxicity of CPF resulting in inhibition of enzyme activities. Native gel electrophoresis revealed single isoform of SOD and MDH enzyme activities exhibiting time and concentration dependent inhibition. Interestingly, three isoforms of esterase activity were witnessed, two isoforms didn't show changes and one isoform was completely inhibited. The observed changes indicated continuous production of reactive oxygen species (ROS) in cells, affecting the integrity and function of cell membrane. Decreased MDH activity indicates reduction of ATP production in the mitochondria leading to susceptibility of fish fingerlings due to the imposed CPF toxicity. Histopathological changes are evident as physiological signatures of chemical interactions in the cell and are prominently used for the evaluation of toxic effects. Gills and eye tissues were selected considering the possible effects on respiratory surfaces and vision impairment. Their tissue sections were observed for changes in primary & secondary lamellae, and retina of the eye respectively. Prominent pathological lesions of gills and retina of the eye include degeneration of cells, fusion, lifting of epithelium and increased cellular space, detachment of pigment epithelium, fusion of photoreceptor cells, respectively on exposure to 30 days of sub lethal concentrations. CPF was found to be highly toxic, affecting the vital functions of respiration, vision and cellular activities leading to susceptibility of fish fingerlings., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The effect of radiation on the aquatic environment is of major concern in recent years. Limited data is available on the genotoxicity of gamma radiation on different tissues of aquatic organisms. Hence, the present investigation was carried out to study the DNA damage induced by gamma radiation in the gill and muscle tissues and their relative sensitivity using the comet assay in the freshwater teleost fish, common carp (Cyprinus carpio). The comet assay was optimized and validated in common carp using cyclophosphamide (CP), a reference genotoxic agent. The fish were exposed (acute) to various doses of gamma radiation (2, 4, 6, 8 and 10Gy) and samplings (gill and muscle tissue) were done at regular intervals (24, 48 and 72h) to assess the DNA damage. A significant increase in DNA damage was observed as indicated by an increase in % tail DNA for all doses of gamma radiation in both tissues. We also observed a dose-related increase and a time-dependent decrease of DNA damage. In comparison, DNA damage showed different sensitivity among the tissues at different doses. This shows that a particular dose may have different effects on different tissues which could be due to physiological factors of the particular tissue. Our study also suggests that the gills and muscle of fish are sensitive and reliable tissues for evaluating the genotoxic effects of reference and environmental agents, using the comet assay., (Copyright © 2017. Published by Elsevier Inc.)

Petroleum hydrocarbons are one of the primary organic chemicals found in water bodies, and the water-soluble fraction of petroleum (WSFP) may be responsible for much of the toxic effects. In the present study, genotoxicity assays and histopathological analysis of the gills were analyzed for two experimental protocols: 1) Juvenile Centropomus parallelus were exposed to different concentrations of WFSP (0%, 25%, 50% and 75%) for 96h; 2) A second fish group was exposed to 50% WFSP for 168h followed by a post-exposure period for 168h in clean water (recovery). The total benzene, toluene, ethyl benzene and xylene (BTEX) and polycyclic aromatic hydrocarbon (PAH) concentrations at time 0 were 254μgL -1 and 4.72μgL -1 in 25%; 552.9μgL -1 and 9.36μgL -1 in 50%; and 842.4μgL -1 and 9.97μgL -1 in 75% WSFP, respectively. Based on the alkaline comet assay, the damage index (DI) values of fish exposed to 25% WSFP for 96h were significantly higher than those in the control group, and in the micronucleus test, the higher damage values were found in fish exposed to 75% WSFP. Furthermore, this last genotoxic test showed recovery after 168h. At all concentrations of WSFP, several histopathological changes were observed, and overall, most of these changes observed in the gills were classified as proliferative changes and represented a protective mechanism against pollutant uptake. Based on the recovery experiment, the damage was also significantly reduced after recovery. Our results showed that short-term exposure to WSFP compounds triggered cellular alterations in C. parallelus, but total recovery did not occur with time. Additionally, the different periods of exposure were not sufficient to induce severe gill damage in C. parallelus. Moreover, this fish demonstrated its usefulness as a sentinel species., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Sublethal effects of the pesticide chlorpyrifos were evaluated in the crab Zilchiopsis collastinensis (Decapoda, Trichodactylidae). Crabs were exposed to high concentrations of chlorpyrifos at the beginning of the experiment and controlled dilution, under natural light and temperature conditions. A control and three concentrations (22.4, 41.25 and 61.4µg chlorpyrifos L -1 ) were evaluated in triplicate. Nine crabs per concentration and day were used. The gills, hepatopancreas and ovaries were sampled before pesticide exposure (day 0) and 8, 15 and 22 days later, when concentrations were diluted and below the detection limits. The histopathological effects and their variations in time were observed and quantified. In gills, hyperplasias were observed in several cases, mainly in crabs exposed to chlorpyrifos. The number of collapsed lamellae and the number of affected lamellae quickly increased in exposed crabs, as effects were observed on day 8 and remained until day 22. In hepatopancreas there was an increase in the number of F and B -cells and affected tubules, especially after 22 days of exposure (p<0.05). In ovaries, there were no effects on gonadosomatic indexes or oocyte volume, but there was a significant increase in the atretic oocyte proportion related to pesticide exposure (p<0.05). The histopathological effects on the gills, hepatopancreas and ovaries were observed after exposure and persist even after dilution, and might be related to earlier exposures. Thus, these histopathological effects might be used as pesticide biomarkers even after the pesticide is not detected by chemical methods., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Metal uptake by biota due to elevated environmental concentrations elicits oxidative stress and could lead to pathological outcomes. The relationship between the histopathological profile of hepatopancreas and gills and altered biochemical features (antioxidant enzymes i.e. GSH, GPx, CAT, SOD, lipid peroxidation (MDA) and serum protein) in the blue crab, Callinectes amnicola from contaminated parts of the Lagos Lagoon was investigated. Monthly crab, sediment and surface water samples were taken from effluent receiving areas of the Lagos lagoon i.e. Makoko, Okobaba, Iddo, Ikoyi and Mid-lagoon (control site) over an 18-month period and analyzed for metal levels (Pb, Cd, Zn and Cu). Significantly higher levels of GPx and lower levels of Pb, Zn and Cu was recorded in gills and hepatopancreas of crabs from the mid-lagoon compared to crabs from other sites. Reaction patterns of gills across the different sites of the lagoon included regressive (ranging from epithelial lifting, disruption of pilaster cells, detached cuticle to focal necrosis) and circulatory disruptions (oedema); increased activity of GSH and GPx in gills were positively correlated with lesions of lower importance factor. Reaction patterns in hepatopancreas were more regressive including vacuolation/infiltration of fatty lobules, necrosis, granuloma, disintegrated lumen, atrophied tubules and loss of lobular hepatocyte structure; increased activity of GSH, GPx and CAT were positively correlated with lesions of low importance factor in the hepatopancreas. Findings show that lesions in both gills and hepatopancreas of the blue crab could be associated with uptake of metals, depleted antioxidant activity and incidence of lipid peroxidation in tissue., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Sugarcane vinasse is one of the main residues generated by the transformation of cane into ethanol. Because of the high organic content (COD), high biochemical oxygen demand (BOD), low pH, the large amount that this residue is generated (15l for every liter of ethanol produced) and their use as fertilizer on the sugarcane crop, this residue is potentially polluting to the soil ecossystem and by percolation to water ecossystem too. Thus, this study aimed to assess the toxicity of vinasse by analyzing Oreochromis niloticus gills exposed to different dilutions (1%, 2.5%, 5% and 10%) in two bioassays. The gills were collected, fixed and analyzed using ultra morphological, histological, and histochemical techniques. After exposure to the vinasse, a statistically significant reduction of the ridges present on the surface of pavimentous cells was observed in one of the bioassays; such structures are responsible for mucus retention, which helps to protect the tissue. In addition, an intumescence of the cells was observed in the treatments with vinasse as well as an increase in the amount of chloridric cells. Some striking tissue changes detected in the treatments were epithelial detachment and loss of integrity of secondary lamellae, causing their rupture and consequent hemorrhage. In the first bioassay, the amount of these changes was statistically significant at the 5% dilution, and the focus of hemorrhage was significant at all dilution ratios. In the second bioassay, the epithelial disorganization was statistically significant only at the 2.5% dilution of vinasse. Moreover, for both bioassays performed, a significant increase in mucous cells was observed when compared with the control. Our results demonstrate the toxic action of sugarcane vinasse, which caused histopathological changes in the exposed animals at all four dilution tested. This highlights the need for caution in the disposal of sugarcane vinasse on the soil, especially due to its capacity for being leached or percolated into water resources, which could seriously damage aquatic fauna., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Carbofuran is a nematicide insecticide with a broad spectrum of action. Carbofuran has noxious effects in several species and has been banned in the USA and Europe; however, it is still used in Brazil. Aquatic organisms are not only exposed to pesticides but also to manufactured nanoparticles, and the potential interaction of these compounds therefore requires investigation. The aim of this study was to examine the histopathological alterations in the gills of Nile tilapia (Oreochromis niloticus) to determine possible effects of exposure to carbofuran, nitric acid-treated multiwalled carbon nanotubes (HNO3-MWCNTs) and the combination of carbofuran with nanotubes. Juvenile fish were exposed to different concentrations of carbofuran (0.1, 0.5, 2.0, 4.0 and 8.0mg/L), different concentrations of HNO3-MWCNTs (0.5, 1.0 and 2.0mg/L) or different concentrations of carbofuran (0.1, 0.5, 2.0, 4.0 and 8.0mg/L) with 1.0mg/L of HNO3-MWCNTs. After 24h of exposure, the animals were removed from the aquarium, the spinal cord was transversely sectioned, and the second gill arch was removed for histological evaluation. Common histological changes included dislocation of the epithelial cells, hyperplasia of the epithelial cells along the secondary lamellae, aneurism, and dilation and disarrangement of the capillaries. All the groups exposed to carbofuran demonstrated a dose-dependent correlation in the Histological Alteration Index; the values found for carbofuran and carbon nanotubes were up to 25% greater than for carbofuran alone. This result indicates an interaction between these toxicants, with enhanced ecotoxic effects. This work contributes to the understanding of the environmental impacts of nanomaterials on aquatic organisms, which is necessary for the sustainable development of nanotechnologies., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Female individuals of Hyphessobrycon eques were exposed to Diflubenzuron (Dimilin(®)) in order to determine whether exposure to sublethal levels of this insecticide causes changes in gill morphology. Fish were exposed to 0.01, 0.1 and 1.0mgL(-1) for 96h and 17 days and then submitted to pathological and histometric evaluation. Pathological lesions, such as hyperplasia, lamellar fusion, vascular congestion, secondary lamellar disarray, vasodilatation, hemorrhage and increased lamellar epithelium, were significantly more common in the gills of fish exposed to Dimilin(®) than the control. Histometric analysis documented significant changes in blood vessel diameter, primary lamellae width and secondary lamellae length, and the appearance of hemorrhage foci in all concentrations tested. Even at low Dimilin(®) concentrations, the histopathological alteration index was mild to moderate, thereby indicating that the function of this tissue was compromised. These findings indicate that indiscriminate use of Dimilin(®) can adversely affect the structural integrity of the gills of H. eques, which can cause numerous problems for fish farming systems., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The combined use of guided quantitative expert analysis and of multivariate exploratory data analysis is reported as a robust, sensitive and sufficiently specific approach to study European sea bass gill secondary lamellar pathology after exposure to incremental doses of cadmium and terbuthylazine up to 48h. The following elementary pathological findings were considered: "epithelial lifting", "epithelial shrinkage", "epithelial swelling", "pillar cells coarctation", "pillar cells detachment", "channels fusion", "chloride cells swelling", and "chloride cells invasion". The relative spatial extension was determined according to exposure class and data were analyzed by means of canonical correspondence analysis (CCA), linear discriminant analysis (LDA) and canonical variates analysis (CVA). Histologically and ultrastructurally, cellular shrinkage/coarctation prevailed in cadmium exposed lamellae, whereas cellular swelling and epithelial lifting were predominant in terbuthylazine exposed lamellae compared to unexposed fish. Both CCA and CVA permit a good graphical data grouping according to exposure classes by means of the convex hull minimum polygons. This also reveals exposure dose and time gradients in CCA plot. Accordingly, epithelial swelling and epithelial shrinkage were comparatively associated to higher exposure time, whereas epithelial shrinkage and pillar cells coarctation were comparatively associated to higher exposure dose. LDA with only "epithelial shrinkage", "epithelial swelling" and "pillar cells coarctation" in the model classified correctly 87.5% of the cross-validated cases. A possible pathogenetic relationship between the discriminant elementary lesions and the toxic mode of action at the cellular level of both cadmium and terbuthylazine is also discussed., (Copyright © 2016 Elsevier Inc. All rights reserved.)

In aquatic environments, bivalve molluscs are used as sentinel species for environmental biomonitoring. In this study Pinna nobilis specimens, the biggest Mediterranean bivalve, were collected in the Magaluf bay (Mallorca), a touristic location and in a pristine area of the Cabrera National Park as the control location. Histological and histochemical analysis in gills of specimens sampled from Magaluf exhibited evident tissue alterations with high presence of haemocytes. Lower acetylcholinesterase (AChE) activity and protein expression were also found in the gills of specimens collected from Magaluf compared with the control area. The determination of antioxidant enzyme activities, such as superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, showed a higher activities of these antioxidant enzymes and total glutathione content in samples from Magaluf bay than in Cabrera. In conclusion, the present study demonstrated that human activities result in morphological tissue alterations and a reduced AChE activity in gills of P. nobilis. Moreover, these stressful environmental conditions induced an adaptive response in P. nobilis as evidenced by increased antioxidant defences and a decreased AChE activity., Capsule: The human activities induce oxidative stress in P. nobilis as evidenced by increased antioxidant defences and a decreased acetylcholinesterase activity., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The acute toxicity test of Cu including range-finding and definitive test, was performed on golden apple snails, Pomacea canaliculata. The median lethal concentrations (LC50) of Cu at exposure times of 24, 48, 72 and 96 h were 330, 223, 177 and 146 µg/L, respectively. P. canaliculata were exposed to Cu at 146 µg/L for 96 h to study bioaccumulation and histopathological alterations in various organs. Snails accumulated elevated levels of Cu in gill, and lesser amounts in the digestive tract, muscle, and digestive gland. Histopathological investigation revealed several alterations in the epithelia of gill, digestive tract (esophagus, intestine, rectum), and digestive gland. The most striking changes were observed in the epithelium of the gill in which there was loss of cilia, an increase in number of mucus cells, and degeneration of columnar cells. Similar changes occurred in digestive tract epithelium. The digestive gland showed moderate alterations, vacuolization and degeneration of cells and an increase in the number of basophilic cells. We concluded that, P. canaliculata has a great potential as a bioindicator for Cu, and a biomarker for monitoring Cu contamination in aquatic environment., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Quantification of histopathological alterations in the gills of Vardar chub (Squalius vardarensis Karaman) was performed in 2012 in rivers of north-eastern Macedonia, with the aim to examine the effects of water quality in the rivers (Zletovska and Kriva River-impacted by active Pb/Zn mines; Bregalnica River-contaminated by agricultural waste). The biological alterations in chub were classified as: circulatory disturbances, regressive and progressive changes, but their severity differed. Altogether the mildest changes were observed in the gills of chub from the Bregalnica River, a less polluted river, whereas mining impacted rivers were characterized by more severe alterations. In the gills of chub from the Zletovska River, which is highly contaminated with numerous metals, sulphates and chlorides, the highest lesion indices were found for the regressive changes of both epithelium and supporting tissue, with typical lesions referring to atrophy, thinning and lifting of epithelial cells, necrosis of epithelium and chloride cells, as well as deformations of lamellar cartilaginous base. Gill damages of chub from the Kriva River were overall milder compared to the Zletovska River, in accordance with pollution status. In the gills of chub from that river, progressive changes were more pronounced, specifically severe hyperplasia of mucous cells and epithelium in the interlammellar space, leading to fusion of lamellae, as well as hypertrophy of chloride cells. The comparison between seasons indicated higher intensity of progressive changes in all three rivers in autumn, when water level was very low, and consequently, water contamination was more pronounced due to concentration effect. The pattern and severity of histopathological alterations in the chub gills reflected differences in contamination levels and type of contaminants in different rivers and sampling periods, and thus have been proven as a valuable indicator of water quality., (Copyright © 2015 Elsevier Inc. All rights reserved.)

In this work, the effects of a pulse exposure of endosulfan on hepatopancreas, gills and ovary of the burrowing crab Zilchiopsis collastinensis were evaluated. The crabs were exposed to three sublethal concentrations in a pulse system with controlled dilutions. Water samples for pesticide concentrations measurements and crab tissue samples were taken when applications were made and 2, 8, 15 and 22 days after administering the pesticide. The exposure to endosulfan caused an increase in B cell number and a decrease in F and R cell number (p<0.05). Necrotic tubules, abnormal lumen and other histopathologies were observed in the hepatopancreas of crabs exposed to endosulfan. There was an increase in the proportion of collapsed gills caused by endosulfan effects. Other effects as hyperplasia were also observed. There were no changes in the gonadosomatic index of exposed crabs; however there were changes in the volume of oocytes of exposed crabs in certain days (p<0.05). The increase in B cell number and the consequent reduction in F cell number may be related to the detoxification processes. The changes in cell number within the hepatopancreas and the histopathologies observed both in hepatopancreas and gills might be used as endosulfan exposure indicators., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Through the integration of chemical, biochemical and morphological analyses, this study investigated the effects of multiple pollutants on environmental biomarkers, such as gill histopathological changes and hematological and biochemical parameters, in Oreochromis niloticus exposed to four sites in the Jacuipe and Subaé rivers over seven days. Sediment analyses identified Sapelba as the most contaminated site, followed by Oliveira de Campinhos, Santo Amaro and Jacuípe. Water analyses revealed aluminum, iron and manganese at all sites. Aluminum and other metal were also detected in the gills of fishes. Fish exposed to the Sapelba site exhibited significant necrosis formation, as well as higher hematological parameters and trend to increase of cortisol levels. However, filament epithelium proliferation was higher at the Oliveira de Campinhos and Santo Amaro sites, at which the lowest levels of the hematological variables were observed. Multivariate analysis grouped some gill histopathological changes together, such as epithelial detachment with edema and lamellar epithelial proliferation with the lamellar fusion of adjacent filaments, revealing relationships among them. Positive associations were identified between sediment contamination and necrosis and cortisol, while water contamination was related with filament epithelium proliferation, aneurism, lamellar fusion and several hematological parameters. Furthermore, relationships between blood parameters and gill histopathological changes demonstrated a joint physiological response that may have resulted from environmental variables such as dissolved oxygen. The results exhibited the direct influence of xenobiotics on these biomarkers but also highlighted the need to consider the complexity of environmental factors to optimize the adoption of these environmental predictive tools., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The largest Brazilian terrestrial province of petroleum mining is located at the margins of Urucu River, Amazonas. Mined crude oil is transported along 400 km across Solimões River to be refined in Manaus. Thus, the main goal of this study was to evaluate the effects of crude oil exposure on biochemical, physiological and behavioral parameters of juveniles of the Amazonian fish tambaqui (Colossoma macropomum). The toxicity of water-soluble and insoluble oil fractions and the influence of a layer formed by the oil on the water surface from low and high concentrations of crude oil were analyzed. The results showed a strong physical effect of oil at the water surface and a significant effect on fish behavior. Swimming time and response to alarm substance decreased when fish was exposed for just one day to water insoluble fraction, and remain lower after 30 days of exposure, compared to control. Chronic exposure to water insoluble fraction of the inert oil also affected these two parameters. Critical swimming velocity decreased in fish exposed to both crude and inert oil water insoluble fraction. These reductions are possibly related to a decrease in aerobic capacity. Only exposure to high concentrations of petroleum water-soluble fractions induced transient alterations of the analyzed parameters. The exposure of fish to low and high concentrations of water insoluble fraction of Urucu oil caused a reduction of responses to alarm substance, spontaneous swimming activity and swimming capacity (Ucrit), decreased activity of acetylcholinesterase, and increased activity of alkaline phosphatase. Severe hypertrophy of lamellar epithelium and extensive lamellar fusion of the gills were also observed. Overall, these results show significant behavioral and physiological changes caused by the oil layer on the water surface, which means that toxicity of petroleum produced by its chemical components is, in fact, in this fish species, enhanced by the presence of an oil phase as a physical barrier., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental pollutants because of their widespread use as flame retardants in various consumer products (plastics, textiles, electronic appliances and building materials) and their long half-life. BDE-47 (2,2',4,4'-tetrabromodiphenyl ether) is the major PBDE congener detected in the environment and in animal tissues. In the present study, the histopathological effects are examined of BDE-47 on the gills, intestine and liver tissues of juvenile turbot (Psetta maxima).The specimens were exposed to two concentrations of BDE-47 (0.03 and 0.3 µg/L) for a period of 15 days. The histological changes were detected microscopically and evaluated with quantitative or semi-quantitative analyses. At the doses of BDE-47 assayed, the most common gill injuries were lamellar fusion, blood congestion and hyperplasia and hypertrophy of the epithelial and mucous cells. In the intestine of fish exposed to BDE-47, the alterations detected were hyperplasia and hypertrophy of mucous cells. Hepatic lesions in the liver of fish exposed to BDE-47 were characterized by circulatory disturbances, irregular morphology of hepatocytes, cellular and nuclear hypertrophy, and nuclear vacuolation and pyknosis. As BDE-47 is present in food and other material related to aquaculture systems, our results indicate that exposure to this pollutant could have serious consequences on health in turbot and other cultured fish., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The exposure to a world-wide used herbicide atrazine (ATZ) (96h exposure to 2, 10, and 100μgL(-1)), was investigated on the freshwater fish Rhamdia quelen through a multi biomarker approach. Liver histopathology revealed leukocyte infiltration, hepatocyte vacuolization like steatosis and necrosis areas, leading to raised lesion index levels in all tested concentrations. The increase of free melanomacrophage numbers was observed. Gill filaments revealed considerable loss of the microridges on pavement cells at 10 and 100μgL(-1) of ATZ, and a significantly increased of chloride cell (CC) number and density on apical surface area at 100μgL(-1) of ATZ. CAT, GST, GPx, and GR activities were inhibited by all tested concentrations. GSH levels were reduced in individuals exposed to 100µgL(-1). Osmoregulatory function was also disturbed. We observed an increase of plasma magnesium concentrations at 10µgL(-1). Additionally the inhibition of branchial carbonic anhydrase activity was observed at 100µgL(-1). In the kidney, carbonic anhydrase activity decreased only in the group exposed to 2µgL(-1). These results suggest that ATZ, represents a potential ecotoxicological hazard and can be hepatotoxic and nephrotoxic even low concentrations. The current study was the first to show the nephrotoxic effect of ATZ in fish. Besides, in Brazil, the environmental protection agency (CONAMA) establishes that the maximum allowed level of dissolved ATZ in water is 2μgL(-1), but the present results showed that this concentration may cause histopathological, biochemical and physiological changes in R. quelen., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Present study was designed to observe the effects of (60)Co gamma radiation in behavioral and histological changes in the gills of giant fresh water prawn Macrobrachium rosenbergii. The adult prawns were irradiated with four different dose levels (3mGy, 30mGy, 300mGy and 3000mGy) and the control group (without irradiation) was maintained separately. Behavioral changes like hyperactivity, loss of balance, reduced swimming rate, slower rate of food intake and convulsions were observed in higher dose levels of 300mGy and 3000mGy. The histological alterations such as accumulated haemocytes in haemocoelic spaces, abnormal gill tips, lifted lamellar epithelium, swollen and fused lamellae, hyperplasic, necrotic, clavate-globate and complete disorganization of lamellae were observed in (60)Co gamma irradiated prawns. Significantly more considerable histological alterations were observed in the highest dose level of 3000mGy, but no mortality was evidenced. This study serves as biomonitoring tool to assess the radiation pollution in the aquatic environment., (Copyright © 2013 Elsevier Inc. All rights reserved.)

There is little existing information on the sub-lethal effects of experimental exposure of Arabian Gulf fish to oil pollution. This study investigated the potential sub-lethal effects of the water accommodated fraction (WAF) of light Arabian crude oil, dispersed oil and dispersant (Maxi Clean 2) on the gills of the juvenile rabbit fish (Siganus canaliculatus), observing several histopathological biomarkers at different time points and different doses. These laboratory exposures simulated a range of possible oil pollution events. Significant alterations in four health categories (circulatory, proliferative, degenerative and inflammatory) were identified and form the basis for understanding the short-term response of fish to oil. Evaluations of histopathological lesions in gill tissue were carried out following 3, 6, 9, 12, 15, 18 and 21 days of exposure. The main lesions observed and quantified were lamellar capillary aneurysms, vasodilatation of lamellae, hemorrhage, edema, lifting of lamellar and filamentary epithelium and epithelium necrosis, epithelial and chloride cell hypertrophy and hyperplasia, fusion of adjacent lamellae, epitheliocystis and inflammatory infiltration. Exposure of juvenile fish to WAF, dispersant oil and dispersant caused significant changes in the gill lesions and reaction patterns. Dispersed oil caused the most significant effect followed by WAF and then dispersant. The present study is one of the first which explores the relationship between oil pollution and epitheliocystis and reports that exposure to crude oil and dispersed oil increases the prevalence of epitheliocystis formation under controlled laboratory conditions., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The Northwestern Portuguese region is densely populated and highly industrialized, suffering from high anthropogenic pressure. To assess the biological effect of the several pollutants that are constantly released to the water, a biomarker-based biomonitoring is a promising approach that may provide early-warning signals of pollutants exposure. Fish gill is the first target of pollutants action, thus histopathological and biochemical changes may constitute potential biomarkers. To evaluate this hypothesis, three native fish species (barbel-Luciobarbus bocagei, chub-Squalius carolitertii and nase-Pseudochondrostoma sp.) were sampled in Northwestern Portuguese rivers, the gill histopathological changes were qualitative and quantitatively analyzed and the lipid peroxidation and glutathione-S-transferase activity were determined. A multivariate statistical analysis was performed to establish correlations between these biological responses, environmental variables and ecological status. The quantitative evaluation of the main histopathological changes and oxidative stress responses emphasize the differences, among species, in the responses to the presence of contaminants in water. Discriminant canonical analysis showed that filament epithelium proliferation, necrosis and GST activity were the main contributors to discriminate the ecological status classification. In addition, the results showed that a wide range of environmental factors are influencing fish physiology. In conclusion, the gill biological responses, although not reflecting specific contaminants, can be used as biomarkers of ecosystems perturbation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Pharmacochemicals usage in fish farming disease treatment can cause morphological and functional changes in absorption capacity, metabolism and excretion organs. The aim of this research was to evaluate the histopathological biomarkers in the gills, liver, kidney and skin of pacu (P. mesopotamicus), which have been infected with A. hydrophila and treated with oxytetracycline (OTC) and florfenicol (FFC). Fish were exposed to 2.4×10(7) mL(-1) of A. hydrophila bacteria experimental infection and after 24h exposed to FFC treatment for ten days and OTC for seven days. OTC was not effective in the A. hydrophila control in pacu in up to 170.0 mg kg(-1) concentration. Nevertheless, FFC was 100% effective with 10.0 mg kg(-1) concentration. After the treatment, skin, gills, liver and kidney samples were collected and processed for histopathological analysis. A. hydrophila caused lamellar fusion, sub epithelial edema, mucous hypertrophy and hyperplasia, lining, pillar and chloride cells. Hepatocytes hypertrophy was observed on liver, as a result of the antibiotics metabolism and bacteria cell wall. The histopathological biomarkers show the effects of the presence of the A. hydrophila. The use of the antibiotic florfenicol decreases the bacterial action effectiveness on tissues evaluated. Thus, the histopathological biomarkers show the A. hydrophila effect and the antibiotics treatment. The skin and liver are exposure biomarkers for both., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Mass fish mortalities have been reported in the past decade from British waters, often coinciding with blooms of filamentous actinobacteria, particularly strains of Streptomyces griseus. The present study has shown that some fractions of the exudate of S. griseus, prepared after a series of high pressure liquid chromatography (HPLC) separations, and analysed with liquid chromatography mass spectrometry (LC-MS), induced pathological changes to the gills of carp and/or tench fry following exposure under laboratory conditions up to 96 h Similar changes were induced by streptomycin, a secondary metabolite of S. griseus, and these included loss of microridging and fusion of secondary lamellae, with carp fry in the case of the exudate of S. griseus being more sensitive than tench fry, especially with exposure to fraction 9 and selected sub-fractions of 9. Some deformities using a severity index were also observed in the head capsule of larvae of the non-biting midge Chironomus riparius, including loss and splitting of teeth on the mentum. The results are discussed in relation to further identification of metabolites derived from samples of the organic filtrate of S. griseus and implications for the functioning of freshwater ecosystems., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The impact of acute (48 h) and subchronic (14 days) exposures to environmentally realistic atrazine concentrations (2, 10 and 25 μg L(-1)) were evaluated on the gills of Prochilodus lineatus by assessing the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), the levels of reduced glutathione (GSH) and lipid peroxide (LPO) as well as the histopathological damage. Acute and subchronic exposure to atrazine at 2 or 25 μg L(-1) did not change the activities of GST, SOD, CAT or GPx or the concentrations of GSH and LPO; however, subchronic exposure to 10 μg L(-1) increased the activity of GST, SOD and CAT and the LPO level. Histopathological indexes indicated normal gill function with scattered epithelial changes after acute and chronic exposure to 2 or 10 μg L(-1) of atrazine; however, fish chronically exposed to 25 μg L(-1) of atrazine, although had scattered lesions, the severity of lesions resulted in slightly to moderately gill damage. Acute exposure to atrazine decreased the type 3 MCs (containing acid mucosubstances with sulfate esters) in fish exposed to 2 or 10 μg L(-1) and increased the type 4 MCs (containing all types of mucosubstances) in fish exposed to 25 μg L(-1). Chronic exposure to atrazine reduced the type 3 MCs in fish exposed to 10 or 25 μg L(-1). The gills showed a low sensitivity to atrazine after acute exposure. However, the persistence of atrazine in water (subchronic exposure) promoted an increase of LPO levels in the gills and increased the frequency and severity of histopathological changes. The decreased density of type 3 MCs in fish exposed to atrazine suggests a mechanism to wash toxic substances away from the gill surface., (Copyright © 2012 Elsevier Inc. All rights reserved.)

An oil spill into the River Lambro occurred on 23 February 2010 and reached the Po River the following day. Breams captured here on 1 March 2010, along with a sample from a control site, were examined by light and electron microscopy. The main affected organs were skin and gill with slight or no damage to liver, kidney, and intestine. The gills exhibited lamellar aneurisms, fusion of secondary lamellae, edema with epithelial lifting, mucous cell hypertrophy, and mucus hypersecretion. Significantly higher mucous cell density was observed in the skin of exposed fish. Histochemical staining revealed that acid glycoconjugates were prevalent in epidermal mucous cells in the exposed Abramis brama, whereas neutral and mixed glycoconjugates were dominant in the control fish. Rodlet cells were significantly more abundant in the kidney of exposed fish and showed ultrastructural differences compared to controls. These histopathologic effects were indicators of chemical stress due to exposure to oil. The present study is one of the first which explores the acute effects of this incident and makes part of a few reports focused on freshwater oil spill., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The present study was conducted to determine interactive effects of waterborne co-exposure of copper (Cu) and calcium (Ca) on Cu accumulation, enzymatic activities and histology in yellow catfish Pelteobagrus fulvidraco and test the prediction that Ca could protect against Cu--induced toxicity in the fish species. Yellow catfish were exposed to 0, 1.0, 2.0 mg Cu/l, in combination with 0 and 50 mg Ca/l. Waterborne Cu and Ca co-exposure influenced the majority of tested enzymatic activities (succinate dehydrogenase, malic dehydrogenase, lactate dehydrogenase, lipoprotein lipase and hepatic lipase), and changed Cu contents in several organs (gill, liver, kidney, gastrointestine and muscle). For histological observations, at the same Ca level, waterborne Cu exposure induced injuries in gills and liver. However, Ca addition seemed to mitigate the severity of Cu--induced injuries. Thus, our study demonstrated that Ca had the capacity to reduce Cu toxicity in P. fulvidraco., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Although fish and aquatic organisms can be in contact with the cyanotoxin cylindrospermopsin (CYN), toxicological studies are practically nonexistent. CYN has a late and progressive acute toxicity in rodents, but no data have been reported in fish. In this work, tilapia (Oreochromis niloticus) were exposed for the first time to an acute dose of CYN (200 μg/kg fish) by intraperitoneal (i.p.) injection, and the effects were compared with the oral route (gavage). In both cases, fish were sacrificed after 24 h or 5 days of the toxin administration. CYN induced multiorganic damage, being the liver and kidney the main targets of toxicity. The histological findings were more pronounced after i.p. administration (in the liver, kidney, heart, gills) with the exception of the gastrointestinal tract. The time of sacrifice influenced the degree of histological damage in all organs studied, and was more severe after 5 d in comparison to 24 h. Moreover, CYN induced an increase in the average nuclear diameter of hepatocytes in the liver, and decreased cross sections of proximal and distal convoluted tubules in the kidney. The changes in these parameters were also more severe by i.p. route, and with the time of sacrifice, supporting the histopathological results obtained in these organs. Thus, both parameters could be useful for quantifying the extent of the damage in fish after CYN exposure., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The present study was conducted to determine the metal accumulation, antioxidant enzymatic response, hepatic intermediary metabolism and histological changes in Synechogobius hasta exposed to 0.35 (control), 9.7 and 19.2mg/L Zn, respectively, on the 0, 4th, 8th and 12th day. Waterborne Zn exposure significantly reduced hepatosomatic index, hepatic lipid contents and fatty liver occurrence rate, increased Zn, Fe and Mn contents and reduced the contents of Cu and Ca in liver, and increased muscle Zn content. Waterborne Zn exposure also significantly influenced enzymatic activities involved in antioxidant responses (superoxide dismutase, catalase, glutathione-S-transferase, malondialdehyde) in liver and spleen, and changed hepatic intermediary enzymatic activities (succinate dehydrogenase, malic dehydrogenase, lactate dehydrogenase, lipoprotein lipase, hepatic lipase), impaired the histological structure of the gill and spleen, and reduced vacuolated hepatocytes. Thus, our study demonstrated for the first time that waterborne Zn exposure could reduce fatty liver syndrome in S. hasta., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The present study was conducted to determine antioxidant responses, hepatic intermediary metabolism, histology and ultrastructure in Synechogobius hasta after a 15-days of waterborne cadmium (Cd) exposure at the concentrations of 0 (control), 0.10, 0.17 and 0.29 mg Cd/l (corresponding to 0, 12.6%, 21.5% and 36.7% of 96 h LC₅₀), respectively. Growth performance and survival declined, but hepatosomatic index (HSI) increased with increasing waterborne Cd levels (P < 0.05). Waterborne Cd exposure also significantly increased lipid contents in whole body and liver (P < 0.05), and Cd accumulation in whole body, muscle and vertebrae. Waterborne Cd exposure changed hepatic enzymatic activities involved in intermediary metabolism, induced antioxidant responses and increased lipid peroxidation level in the gill, liver and spleen. Waterborne Cd exposure also caused considerable histological alterations of gill, liver and spleen, led ultrastructures damage of liver and spleen of fish, and induced fatty liver for this fish species., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The organochlorine insecticide endosulfan (ES) is widely used despite its high toxicity to fish (96-h LC(50) median value of 2.6 μg L(-1)). This study aimed to assess the acute toxicity, histological and physiological parameters after exposure to 0; 0.25; 1; 2; 3; 4 and 16 μg L(-1) ES for 96 h under semi-static conditions in a freshwater perciform fish, Cichlasoma dimerus. Prior to death, fish exhibited behavior indicative of neurotoxicity. No difference was found in brain AChE activity. A decrease in erythrocyte mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration in exposed fish suggests a state of anemia. Histological alterations observed in exposed fish included hyperplasia of the interlamellar epithelium, blood congestion in secondary lamellae, and mucous cells hyperplasia and hypertrophy in gills; pycnotic nuclei and hydropic degeneration in liver; testicular damage. These moderate pathological responses in major organs could become crucial during reproduction and under prolonged exposure periods., (Copyright © 2011 Elsevier Inc. All rights reserved.)

In this investigation, effect of cadmium chloride (25 μg/l) on oogenesis of freshwater prawn, Macrobrachium rosenbergii was studied. In vivo experiments were performed with both intact and eyestalk ablated prawns. The intact, cadmium-exposed prawns exhibited decrease in Gonado Somatic Index (GSI) and ovarian development compared to controls. Whereas, ablated treated ovary showed reduction of yolk material and oocyte membrane thickness at the end of 15 days exposure. Interestingly, the control prawn showed normal cellular architecture of gills, hepatopancreas and ovary with mature oocytes. But, the gills of treated prawns showed lamellar hypertrophy, cuticular dystrophy and irregular arrangement of epithelial cells. Hepatopancreas showed reduction in both tubular diameter and basement membrane thickness. Conspicuously, ovary showed hypertrophied primary oocytes with more vacuoles in intact-treated group. Cadmium had increased gonad inhibiting hormone (GIH) secretion and decreased gonad stimulating hormone (GSH) release as evident with the retardation of gonadal maturation in the intact prawns., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The present study aimed to assess the ecological situation in the Pechora River Basin (east part of Sub-Arctic Russia) using histopathologies of fish and to relate fish health to environmental quality. This paper reports histopathological alterations of fish kidney, liver, and gills and their association with chemical contamination of the Pechora River. A variety of histopathological changes was found. Differences between studied species and sites of the Pechora River with regard to the type, prevalence, and severity of lesions were studied. The types of the lesions indicated that fish respond to both direct toxicant effects of contaminated water and sediment, and secondary stress effects caused by factors such as parasitism. The structural modifications found in this study are a result of acute damage associated with short-term exposure as much as chronic response due to long-term pollution., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The current study was conducted to evaluate the ability of Egyptian bentonite (EB) and montmorillonite (EM) for the prevention of genotoxicity, histochemical and biochemical changes induced by aflatoxin B(1) (AFB(1)) using the micronucleus (MN) assay, chromosomal aberrations and DNA fragmentation analysis in Tilapia fish. Six groups of fish were treated for 3 weeks and included the control group, AFB(1)-treated group and the groups treated with EB or EM alone or in combination with AFB(1). At the end of experiment period, blood samples were collected for MN, testosterone and biochemical assays. Chromosomal aberrations were determined in kidney tissues, DNA fragmentation test was determined in liver and testis, whereas histochemical study was carried out on liver, testis and gills. The results indicated that a significant decrease in total protein, albumin, globulin, testosterone and DNA content in liver, gills and testis accompanied with a significant increase in number of micronucleated erythrocytes (MnRBCs), total chromosomal aberrations in kidney and DNA fragmentation in testis and liver of fish received AFB(1) alone. Fish treated with EB or EM alone were comparable to the control regarding the biochemical parameters except testosterone in EB-treated group which was significantly decreased. Both clays did not induce any significant differences in number of MnRBCs, chromosomal aberrations in the kidney, DNA fragmentation in testis, but not in liver of EB-treated group. The combined treatment with AFB(1) and EB or EM succeeded to improve all the tested parameters towards the control values although it did not normalize them. Moreover, the improvement was pronounced in the group received EM plus AFB(1). It could be concluded that EB and EM have the ability to tightly bind AFB(1) in the gastrointestinal tract of fish resulting in decreasing its bioavailability. Moreover, the two tested clays were safe and can be used as potential aflatoxin binders in animal feed., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The alkaline comet assay has been employed for the first time to estimate the basal DNA damage in the digestive gland, gills, kidney and gonads of Octopus vulgaris. Octopuses were captured in two coastal areas adjacent to the cities of Matosinhos (N) and Olhão (S), Portugal. The area of Matosinhos is influenced by discharges of the Douro River, city of Porto, industries and intensive agriculture, while Olhão is an important fisheries port. Previous works point to contrasting metal availability in the two coastal areas. Among the analysed tissues digestive gland presented the highest levels of Zn, Cu, Cd and Pb. Tissues of specimens from Matosinhos exhibited high levels of Cd and from Olhão enhanced Pb concentrations. The DNA damages in digestive gland, gills and kidney were more accentuated in specimens from Matosinhos than from Olhão, suggesting a stronger effect of contaminants. Elevated strand breakages were registered in digestive gland, recognised for its ability to store and detoxify accumulated metals. The DNA damages in kidney, gills and gonads were lower, reflecting reduced metal accumulation or efficient detoxification. The broad variability of damages in the three tissues may also mirror tissue function, specific defences to genotoxicants and cell-cycle turnover., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The present study was conducted to determine growth, hepatic enzymatic activities and histology in Synechogobius hasta exposed to waterborne copper concentrations of 0 (control), 0.15 and 0.3 mg Cu/l, respectively, for 15 days, and explore whether waterborne copper exposure could induce the fatty liver syndrome for the fish species. Growth (WG and SGR) declined, but HSI increased in S. hasta with increasing waterborne copper levels (P<0.05). Waterborne copper exposure also significantly increased lipid content and reduced protein content in both whole body and liver, and increased copper accumulation in whole body and vertebrae. Copper exposure changed hepatic enzymatic activities (SOD, CAT, SDH, PK, LDH, LPL and HL) and increased hepatic lipid peroxidation level, impaired the histological structure of the gill and liver in S. hasta. Thus, our study demonstrated for the first time that waterborne Cu exposure could induce fatty liver syndrome in fish., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Little is known about the immunotoxic effects of sublethal mercury (Hg) exposure in bivalves, and whether or not stimulation of the immune system exacerbates Hg toxicity. The mussel, Mytilus edulis, was exposed to a total inorganic Hg concentration of 50 microgl(-1) as HgCl2 for up to 11 days compared to no added Hg controls. Then the immune functions of haemocytes, haematology, biochemistry and organ histology were assessed. Selected experiments were then repeated in mussels injected with lipopolysaccharide (LPS) to stimulate the immune system prior to Hg exposure. Hg exposure alone caused Hg accumulation mainly in gills and digestive gland, and to a lesser extent in the adductor muscle and haemolymph. This general pattern of Hg accumulation also occurred during the Hg plus LPS experiments. Hg exposure alone caused a transient increase of phagocytosis, but no Hg-dependent effects on neutral red retention or the cytotoxicity of haemocytes. Changes in haemolymph Na+, K+ and glucose levels were negligible during Hg exposure alone compared to controls. However, histological examination showed tissues injuries consistent with inflammation in the gills, digestive gland and adductor muscle during Hg exposure alone. LPS injection had a significant effect (Kruskal Wallis, P=0.02) on circulating haemocytes numbers at the end of the experiment compared to saline injected controls and the Hg+LPS treatment (mean+/-S.E.M., n=6, cells ml(-1)x10(6)); control, 2.1+/-0.08; LPS treated, 3.18+/-0.36, and LPS+Hg, 2.1+/-0.2. The Hg+LPS treatment also caused a transient decline in superoxide dismutase activity in haemocytes (85% decline, Kruskal Wallis, P=0.006) compared to controls. Target tissue inflammation and injury was greatly increased by the effect of Hg exposure with an LPS injection compared to either treatment alone. We conclude that Hg can cause inflammation in mussels in vivo, and that stimulation with LPS can greatly increase Hg-dependent immunotoxicity., (Copyright (c) 2010. Published by Elsevier Inc.)