Aquatic assessment of the chelating ability of Silica-stabilized magnetite nanocomposite to lead nitrate toxicity with emphasis to their impact on hepatorenal, oxidative stress, genotoxicity, histopathological, and bioaccumulation parameters in Oreochromis niloticus and Clarias gariepinus.

BACKGROUND: In recent years, anthropogenic activities have released heavy metals and polluted the aquatic environment. This study investigated the ability of the silica-stabilized magnetite (Si-M) nanocomposite materials to dispose of lead nitrate (Pb(NO3)2) toxicity in Nile tilapia and African catfish. RESULTS: Preliminary toxicity tests were conducted and determined the median lethal concentration (LC50) of lead nitrate (Pb(NO3)2) to Nile tilapia and African catfish to be 5 mg/l. The sublethal concentration, equivalent to 1/20 of the 96-hour LC50 Pb(NO3)2, was selected for our experiment. Fish of each species were divided into four duplicated groups. The first group served as the control negative group, while the second group (Pb group) was exposed to 0.25 mg/l Pb(NO3)2 (1/20 of the 96-hour LC50). The third group (Si-MNPs) was exposed to silica-stabilized magnetite nanoparticles at a concentration of 1 mg/l, and the fourth group (Pb + Si-MNPs) was exposed simultaneously to Pb(NO3)2 and Si-MNPs at the same concentrations as the second and third groups. Throughout the experimental period, no mortalities or abnormal clinical observations were recorded in any of the treated groups, except for melanosis and abnormal nervous behavior observed in some fish in the Pb group. After three weeks of sublethal exposure, we analyzed hepatorenal indices, oxidative stress parameters, and genotoxicity. Values of alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), urea, and creatinine were significantly higher in the Pb-intoxicated groups compared to the control and Pb + Si-MNPs groups in both fish species. Oxidative stress parameters showed a significant decrease in reduced glutathione (GSH) concentration, along with a significant increase in malondialdehyde (MDA) and protein carbonyl content (PCC) concentrations, as well as DNA fragmentation percentage in the Pb group. However, these values were nearly restored to control levels in the Pb + Si-MNPs groups. High lead accumulation was observed in the liver and gills of the Pb group, with the least accumulation in the muscles of tilapia and catfish in the Pb + Si-MNPs group. Histopathological analysis of tissue samples from Pb-exposed groups of tilapia and catfish revealed brain vacuolation, gill fusion, hyperplasia, and marked hepatocellular and renal necrosis, contrasting with Pb + Si-MNP group, which appeared to have an apparently normal tissue structure. CONCLUSIONS: Our results demonstrate that Si-MNPs are safe and effective aqueous additives in reducing the toxic effects of Pb (NO3)2 on fish tissue through the lead-chelating ability of Si-MNPs in water before being absorbed by fish.

Assessment of triclosan induced histopathological and biochemical alterations, and molecular docking simulation analysis of acetylcholinesterase enzyme in the gills of fish, Cyprinus carpio.

Triclosan (TCS), an antimicrobial additive in various personal and health care products, has been widely detected in aquatic environment around the world. The present study investigated the impacts of TCS in the gills of the fish, Cyprinus carpio employing histopathological, biochemical, molecular docking and simulation analysis. The 96 h LC50 value of TCS in C. carpio was found to be 0.968 mg/L. Fish were exposed to 1/1000th (1 µg/L), 1/100th (10 µg/L), and 1/10th (100 µg/L) of 96 h LC50 value for a period of 28 days. The histopathological alterations observed in the gills were hypertrophy, hyperplasia, edematous swellings, and fusion of secondary lamellae in TCS exposed groups. The severity of these alterations increased with both the concentration as well as the duration of exposure. The present study revealed that the activity of antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and reduced glutathione content decreased significantly (p < 0.05) in both concentration and duration dependent manner. However, a significant (p < 0.05) increase in the activity of the metabolic enzymes such as acid phosphatase and alkaline phosphatase was observed in all three exposure concentrations of TCS from 7 to 28 days. The activity of acetylcholinesterase declined significantly (p < 0.05) from 7 to 28 days whereas the content of acetylcholine increased significantly at the end of 28 day. The experimental results were further confirmed by molecular docking and simulation analysis that showed strong binding of TCS with acetylcholinesterase enzyme. The study revealed that long-term exposure to sublethal concentrations of TCS can lead to severe physiological and histopathological alterations in the fish.

Cumulative assessment of Diplectanum spp. occurrence, prevalence, and pathological impact in Dicentrarchus labrax from varied Egyptian fish farms.

Monogenean trematodes, particularly those belonging to the Diplectanidae family, are significant metazoan parasites with substantial implications for aquaculture expansion. This study, investigatied the occurrence, prevalence, and pathological impact of Diplectanum spp. in European seabass (Dicentrarchus labrax) across three distinct Egyptian fish farms. During 2021-2022, we sampled 1800 European seabass (Dicentrarchus labrax) from three Egyptian fish farms (600 fish per farm). Farms 1 and 2 used semi-intensive earthen pond systems, while Farm 3 utilized an intensive floating cage system. Employing Clinical, post-mortem, parasitological, and molecular examination technique. Pathological lesions were identified, including skin and gill discoloration, emaciation, and internal organ abnormalities. Seasonal prevalence exhibited significant variations between farms, with highest rates observed in spring and Farm 3 reached an overall peak prevalence of 84.67 %. Parasitological examination distinguished two Diplectanum species morphologically, while molecular techniques exhibited limited specificity. Histopathology unveiled damage to gill, liver, spleen, kidney, and intestine, attributed to Diplectanum haptors including inflammation and internal bleeding, potentially leading to secondary infections. Molecular identification via PCR targeting ITS and 28SrDNA genes, revealing similar band sizes for the two Diplectanum species, indicating limited intraspecific genetic diversity. The study emphasizes investigating parasitic infections' prevalence and impact in aquaculture, necessitating robust molecular techniques for species differentiation. This study underscores the importance of investigating the prevalence and impact of parasitic infections in aquaculture. It highlights the need for robust molecular techniques to differentiate species. By focusing on Diplectanum spp. infections in D. labrax, the study offers valuable insights into managing parasites in aquaculture effectively.

Toxicological assessment of bromoxynil and 2-methyl-4-chlorophenoxyacetic acid herbicide in combination on Cirrhinus mrigala using multiple biomarker approach.

The widespread application of herbicides raises concerns about their impact on non-target aquatic organisms. This study aimed to evaluate the toxicity of a commercially available herbicide formulation containing Bromoxynil+MCPA (2-Methyl-4-chlorophenoxyacetic acid) on Cirrhinus mrigala (economically significant fish). A total of 210 juvenile fish were subjected to a triplicate experimental setup, with 70 fish allocated to each replicate, exposed to seven different concentrations of herbicide: 0 mg/L, 0.133 mg/L, 0.266 mg/L, 0.4 mg/L, 0.5 mg/L, 0.66 mg/L, and 0.8 mg/L, respectively, for a duration of 96 h. The median lethal concentration (LC50) was determined to be 0.4 mg/L. Significant hematological alterations were observed, including decreases in RBC counts, hemoglobin, hematocrit, and lymphocyte counts, along with an increase in erythrocyte indices. Biochemical analysis revealed elevated levels of neutrophils, WBCs, bilirubin, urea, creatinine, ALT, AST, ALP, and glucose in treated groups. Morphological abnormalities in erythrocytes and histopathological changes in gills, liver, and kidneys were noted. Pathological alterations in gills, liver and kidneys including epithelial cell uplifting, lamellar fusion, hepatolysis, and renal tubule degeneration were observed. Oxidative stress biomarkers such as TBARS (Thiobarbituric Acid Reactive Substance), ROS (Reactive Oxygen Species), and POD (Peroxides) activity increased, while antioxidant enzymatic activities decreased as toxicant doses increased from low to high concentrations. The study reveals that Bromoxynil+MCPA significantly disrupts physiological and hematobiochemical parameters in Cirrhinus mrigala, which highlights the substantial aquatic risks. In conclusion, the herbicide formulation induced significant alterations in various fish biomarkers, emphasizing their pivotal role in assessing the environmental impact of toxicity. This multi-biomarker approach offers valuable insights regarding the toxicological effects, thereby contributing substantially to the comprehensive evaluation of environmental hazards.

Assessment of deltamethrin toxicity in Macrobrachium nipponense based on histopathology, oxidative stress and immunity damage.

Deltamethrin (Del), a commonly used broad-spectrum insecticide, has been reported to have a toxic effect on aquatic animals, but knowledge in freshwater prawns is limited. This study revealed that Del is highly toxic to Macrobrachium nipponens with the 24 h, 48 h, 72 h, and 96 h LC50 values to be 0.268, 0.165, 0.104, and 0.066 µg/L, respectively. To further investigate the toxic effect of Del in M. nipponense and the reversibility of damage, prawns were exposed to 0.05 µg/L Del for four days and then transferred into fresh water for seven days. Histopathological examination, oxidative stress, hepatopancreas function, respiration system, and immune system were analyzed through multiple biomarkers. Results showed that Del exposure caused severe histopathological damage to hepatopancreas and gill in M. nipponense, and the prominent decrease of acid phosphatase (ACP) and alkaline phosphatase (AKP) activity further enhanced the hepatopancreas damage; the accumulation of malonaldehyde (MDA) and hydrogen peroxide (H2O2), and the decrease of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, indicated severe oxidative stress caused by Del. Besides, Del exposure also induced remarkably increased lactic acid (LD) level, decreased lactate dehydrogenase (LDH) activity, and decreased expression of immune-related genes, which demonstrated the respiration disruption and immunosuppression caused by Del. After 7-day decontamination in freshwater, the indicator of hepatopancreas function (ACP and AKP activity) and respiration (LD level and LDH activity) improved to the control group level. However, the histopathological damage and the biomarker in oxidative stress and immune system did not recover to the initial level.

Comparative Assessment of Genotoxic Impacts Induced by Zinc Bulk- and Nano-Particles in Nile tilapia, Oreochromis niloticus.

Fish were separately exposed to 1/2 LC50/96 h values of bulk-Zn and nano-Zn for 7, 14, and 28 days. The induction of micronuclei (MN) and other eight nuclear abnormalities in erythrocytes showed marked time and size dependence. The frequencies of all nuclear anomalies were progressively elevated (p < 0.05) with increasing the time of exposure to both bulk-Zn and nano-Zn. Throughout the study periods, fish exposed to nano-Zn showed the maximum elevation in all studied nuclear anomalies. Based on the fragmented DNA values, both Zn forms induced tissue-specific DNA damage as following gills > liver > muscles. Moreover, nano-Zn exposed groups revealed a maximum percentage of DNA damage among all studied groups, especially after 14 days. The percentage of DNA damage was decreased in all tissues on the 28th day, which reflected the presence of an effective repair mechanism. Finally, nano-Zn exhibited more genotoxic effects than that of its bulk counterparts.

Assessment of Gill Pathological Responses in Yellowfin Sea Bream (Acanthopagrus Latus) Under Aeromonas Hydrophila Exposure.

Bacterial diseases in cultured fish are considered the main problem with aquaculture system in Iran. The gills are multifunctional organs responsible for respiration, osmoregulation, nitrogenous waste excretion, and acid-base balance. Moreover, they are very sensitive to water contamination. Aeromonas hydrophila (A. hydrophila) is an opportunist pathogen responsible for a wide range of diseases in different species of fish. The gill histological alterations were used to assess the effects of A. hydrophila exposure on yellowfin sea bream, Acanthopagrus latus (A. latus). In this regard, 90 A. latus were exposed to the concentrations of A. hydrophila (103 and 106 CFU/ml) for three weeks. The most histopathological alterations in the gill of the exposed fish included hypertrophy and hyperplasia of the epithelial cells, lamellar fusion, club shaping of gill lamellae, lifting of the epithelium and edema of lamellae with large sub-epithelial space, blood congestion, and hypertrophy and hyperplasia of the mucosal cells. The histopathological alterations were observed in the gill of fish exposed to higher levels of A. hydrophila (106 CFU/ml) consisted of aneurysm and hemorrhage with blood congestion. According to the obtained results of this study, A. hydrophila could cause severe histopathological changes in the gill of A. latus and decrease gas change capability in yellowfin sea bream. Furthermore, the findings of the present study suggested that histopathological changes of the gill provide helpful information about the environmental conditions and as particular biomarkers may help the evaluation of fish general health.

Analysis of histopathological abnormalities in the gills of Astyanax jacuhiensis (Characidae) for assessment of water quality in the Ijuí River, southern Brazil / Análisis de anormalidades histopatológicas en las branquias de Astyanax jacuhiensis (Characidae) para la evaluación de la calidad del agua del Río Ijuí, sur de Brasil

The aim of this study was to assess histopathological alterations in the gills of Astyanax jacuhiensis from different points along the Ijuí River and to determine if these abnormalities can be used as biomarkers in biomonitoring studies. Fish specimens were collected from three sites on the Ijuí River in winter and summer and examined histologically for abnormalities of the secondary lamellae of their gills. For each fish, estimates were made of the frequencies of lamellae with edema, hyperplasia, hypertrophy, epithelium lifting, lamellar fusion or deformation, in addition to the overall frequency of abnormal lamellae and the number of abnormalities per lamella. No differences were observed between sampling points during the winter. In summer the frequency of lamellae with hypertrophy was significantly higher at site 3 (Pirapó) than at site 2 (Santo Ângelo) and the frequency of abnormal lamellae was increased at site 1 (Ijuí) in comparison to site 3. Additionally, all three sample points had a significantly higher value in the winter than in the summer for one of the histological parameters analyzed. These results indicate temporal and spatial variation in the level of contamination of the Ijuí River and also shows that fish gill histopathology can be used for in situ biomonitoring studies.

El agua de la cuenca del río Ijuí, en el sur de Brasil, se utiliza principalmente para irrigar los cultivos y para el abastecimiento público de agua. El objetivo del presente estudio fue evaluar alteraciones histopatológicas en las branquias de Astyanax jacuhiensis en diferentes puntos del Río Ijuí y determinar si tales anormalidades pueden ser usadas como biomarcadores en estudios de biomonitoramiento. Los especímenes fueron recolectados en tres puntos del río durante el invierno y el verano y luego las lamelas secundarias de las branquias fueron examinadas histológicamente para la presencia de anormalidades. Para cada pez se estimaron las frecuencias de lamelas con edema, hiperplasia, hipertrofia, desprendimiento del epitelio, fusión y deformación lamelar. Además, se obtuvieron las frecuencias de lamelas alteradas, así como el número medio de cambios por lamela. No se observaron diferencias entre los puntos de recolección durante el invierno. En el verano, la frecuencia de lamelas con hipertrofia fue significativamente mayor en el punto 3 (Pirapó) que en el punto 2 (Santo Angelo), y el punto 1 (Ijuí) presentó mayor frecuencia de lamelas alteradas que el punto 3. Además, en los tres puntos muestreados, el período de invierno presentó valores superiores para uno de los parámetros histológicos analizados. Estos resultados indican variación espacial y temporal en los niveles de contaminación del Río Ijuí y demuestran que el análisis histológico de las branquias de peces puede ser utilizado en estudios de monitoreo in situ.

Assessment of Waterborne Amine-Coated Silver Nanoparticle (Ag-NP)-Induced Toxicity in Labeo rohita by Histological and Hematological Profiles.

Silver nanoparticles (Ag-NPs) have wide applications in the medical field; however, the toxicological effects are still poorly studied. The study was aimed to determine the effects of 15.78 nm spherical and amine-coated Ag-NPs on hematology and histology of gills and liver tissues in 28 days treated Labeo rohita (L. rohita). It was found that Ag-NPs induced alterations in the hematological parameters in a dose dependent manner. The Ag-NPs also induced histological alterations in a dose-dependent manner. In gill tissues, it induced fusion of secondary lamellae, separation of gill epithelium, fusion and necrosis of lamellar cells, hyperplasia, deformed cartilaginous skeleton, separation and lifting of epithelium, and curling of lamellae in a dose dependent manner. In the liver, Ag-NPs produced abnormalities in hepatic tissues by reducing the size of hepatocytes and nuclei, and stimulated the production of necrotic and apoptotic bodies. It was concluded that Ag-NPs are toxic to aquatic organisms and induce hematotoxicity and histopathological conditions in exposed fish.

Comparative assessment of the adverse outcome of wastewater effluents by integrating oxidative stress and histopathological alterations in endemic fish.

This study evaluated the adverse effect of wastewater effluents on three fish species, Carassius auratus, Zacco platypus, and Zacco koreanus, collected in the Eungcheon, Mihocheon, and Busocheon streams, respectively. Fish gills, liver, and kidneys from the mixing zone (MZ) and sites upstream (US) and downstream (DS) of the MZ were analyzed for oxidative stress responses and histology. Catalase and glutathione S-transferase activity was significantly higher at MZ and DS than from US (p<0.05), indicating induction of antioxidant defense mechanisms. Additionally, degree of tissue changes (DTC) indicated highest histopathological alteration in MZ, followed by DS and US. Integrated biomarker response (IBR) for oxidative stress and histopathological alterations showed higher values consistently for Z. koreanus than other two species. Water temperature, EC, and TN levels seemed to be responsible for the observed biomarker responses. These findings indicate that thermal hot spring effluent discharged into Busocheon steam induced the most significant impact on the cool water species (Z. koreanus). Overall, this study suggests that the IBR index is a very useful tool for monitoring in situ adverse effects of wastewater effluents on fish, particularly for histopathological alterations representing prolonged impact.

Toxicity assessment of ZnO-decorated Au nanoparticles in the Mediterranean clam Ruditapes decussatus.

The synthesis of hybrid nanomaterials has greatly increased in recent years due to their special physical and chemical properties. However, information regarding the environmental toxicity associated with these chemicals is limited, in particular in the aquatic environment. In the present study, an experiment was performed in which the marine bivalve (Ruditapes decussatus) was exposed for 14days to 2 concentrations of zinc oxide-decorated Au nanoparticles (Au-ZnONPs: Au-ZnONP50=50µg/L; Au-ZnONP100=100µg/L). The stability and resistance of Au-ZnONPs in the natural seawater were assessed by combining transmission electron microscopy and dynamic light scattering. Inductively coupled plasma-atomic emission spectroscopy revealed uptake of these nanoparticles within clams and their ability to induce metallic deregulation. The results obtained indicate that Au-ZnONPs induce biochemical and histological alterations within either the digestive gland or gill tissues at high concentration. This was deduced from the significant increase in H2O2 level, superoxide dismutase and catalase activities and malondialdehyde content. Furthermore, the toxicity of Au-ZnO nanoparticles was linked with the increase of intracellular iron and calcium levels in both tissues. Histological alterations in gill and digestive gland were more pronounced with Au-ZnONP100 and this is likely related to oxidative mechanisms. Gill and digestive gland are differentially sensitive to Au-ZnONPs if the exposure concentration is higher than 50µg/L. In conclusion, the parameters considered here could constitute reliable biomarkers for evaluation of hybrid nanoparticles toxicity in environmental model organisms. In addition, based on the results obtained, gill and digestive gland of R. decussatus could be proposed as models to detect harmful effects of hybrid nanoparticles.

Avaliação ectoparasitológica, hematológica e histopatológica de traíras Hoplias malabaricus Bloch, 1794 provenientes de açudes localizados no município de Sumé, estado da Paraíba / Ectoparasitologic, hematologic and histopathologic assessment of Hoplias malabaricus Bloch, 1794 from ponds located in Sumé municipality, state of Paraíba, Brazil

Hoplias malabaricus Bloch, 1794 é uma das espécies de peixes mais comumente encontrada nos açudes da Microrregião do Cariri Paraibano, todavia ainda não existem estudos na região sobre a sua fauna parasitária. Em virtude disso, o estudo objetivou caracterizar a fauna ectoparasitológica, o perfil hematológico e os achados histopatológicos das brânquias de H. malabaricus provenientes de quatro açudes localizados no município de Sumé/PB. Em cada açude foram capturados 10 exemplares e foi realizada a análise limnológica da água. Realizou-se a biometria dos exemplares e foram colhidas amostras sanguíneas por venopunção caudal. Os métodos de coleta de parasitos foram realizados segundo as recomendações da literatura. Além disso, foram coletadas amostras de brânquias para avaliação histopatológica. A comparação das médias foi feita pelo Teste Tukey a 5% de probabilidade. Os resultados mostram que a ectoparasitofauna de H. malabaricus provenientes de açudes localizados no município de Sumé/PB apresentou-se diversificada, sendo identificados vários táxons de ectoparasitos na superfície corporal e brânquias. A fauna parasitária promoveu alterações hematológicas e histopatológicas nas brânquias. Além disso, os resultados evidenciam uma relação de epibiose de Epistylis sp. com Lernaea cyprinacea e crustáceos branquiúros em H. malabaricus.(AU)

Hoplias malabaricus Bloch, 1794 is one of the fish species most commonly found in the micro-region ponds of Cariri in Paraíba; however there are no studies in the region on its parasitic fauna. Due to this, the study aimed to characterize the ectoparasitologic fauna, blood profile and histopathological findings of the gills of H. malabaricus from four ponds in Sumé/PB. At each pond 10 specimens were captured and limnological water analysis was performed as the biometrics of specimens and blood samples were collected by caudal venipuncture. Parasite collection methods were used according to literature recommendations. Also gill samples were collected for histopathological assessment. Comparison of the averages were made by Tukey test at a probability of 5%. The results show that H. malabaricus ectoparasite fauna from ponds located in Sumé/PB is diverse, once various ectoparasites taxons are identified on body surface and gills. The parasitic fauna promoted hematological and histopathological changes in the gills. The results show also an epibiosis relationship of Epistylis sp. with Lernaea cyprinacea and branchiurans crustaceans on H. malabaricus.(AU)

Jellyfish Stings Trigger Gill Disorders and Increased Mortality in Farmed Sparus aurata (Linnaeus, 1758) in the Mediterranean Sea.

Jellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses.

In Vivo toxicological assessment of biologically synthesized silver nanoparticles in adult Zebrafish (Danio rerio).

The present study examines the deleterious effect of biologically synthesized silver nanoparticles in adult zebrafish. Silver nanoparticles (AgNPs) used in the study were synthesized by treating AgNO3 with aqueous leaves extract of Malva crispa Linn., a medicinal herb as source of reductants. LC50 concentration of AgNPs at 96 h was observed as 142.2 µg/l. In order to explore the underlying toxicity mechanisms of AgNPs, half of the LC50 concentration (71.1 µg/l) was exposed to adult zebrafish for 14 days. Cytological changes and intrahepatic localization of AgNPs were observed in gills and liver tissues respectively, and the results concluded a possible sign for oxidative stress. In addition to oxidative stress the genotoxic effect was observed in peripheral blood cells like presence of micronuclei, nuclear abnormalities and also loss in cell contact with irregular shape was observed in liver parenchyma cells. Hence to confirm the oxidative stress and genotoxic effects the mRNA expression of stress related (MTF-1, HSP70) and immune response related (TLR4, NFKB, IL1B, CEBP, TRF, TLR22) genes were analyzed in liver tissues and the results clearly concluded that the plant extract mediated synthesis of AgNPs leads to oxidative stress and immunotoxicity in adult zebrafish.

Monitoring and assessment of environmental disturbance on natural Gambusia affinis populations--histopathological analysis.

Physiological investigations are often used to assess the toxic effects of aquatic pollutants in fish and to establish criteria for water quality. In the present study, we tend to investigate the growth performance, skeletal abnormalities, and histological alterations noticed in three natural populations of the mosquitofish Gambusia affinis captured from three estuary sites. The analysis of growth performance demonstrated that the studied populations showed different growth patterns. Additionally, various types of skeletal deformities were observed, and the most commonly affected were the hemal and pre-hemal regions of fishes. For the histological study, gills, liver, and kidney tissues were selected for field monitoring. The major alterations observed in gill tissues were partial fusion of adjacent secondary lamellae, hypertrophy of epithelial cells, and disorganization of pillar cells in many areas of the secondary lamellae. In the liver, significant desquamation of tissues, congestion of the central hepatic vein, and hypertrophy of hepatocytes were noticed. For the kidney tissue, the frequencies of histological alterations showed a significant difference between the studied sites. Moreover, the histological aberrations consisted mainly in glomerule alteration and vacuolation of tubular epithelial cells. Taken together, these data support the hypothesis that the physiological alterations noticed in the present investigation are indicators of sensitivity towards environmental disturbance.

Risk assessment, bioaccumulation of metals and histopathological alterations in Nile tilapia (Oreochromis niloticus) facing degraded aquatic conditions.

Two sampling sites contaminated with high aqueous metal concentrations in the vicinity of metal-related factories (site2) and 7 km downstream (site3) were selected along river Nile. These sites were compared to reference fish farm (site1) that fed on unpolluted water source. Bioaccumulation of metals (Cu, Zn, Pb, Fe, Mn and Cd) in Oreochromis niloticus showed a tissue-specific pattern with high rate of accumulation in gills, liver and kidney. The lowest concentrations of almost all metals were observed in muscle. The accumulated pattern was confirmed by histopathological examination of gills, liver and kidneys. Tissues from site2 and 3 revealed various histopathological alterations ranging from compensatory histological changes to histological damage. Evaluation of human health hazard using metals hazard index values in skin and muscle showed that all metals were in the safe limits for human intake except in the case of zinc and cadmium in skin at subsistence consumption level.

Assessment of genotoxic and mutagenic potential of hexavalent chromium in the freshwater fish Labeo rohita (Hamilton, 1822).

The present study was undertaken to investigate the genotoxicity and mutagenicity of sublethal concentrations of hexavalent chromium (potassium dichromate) in the Indian major carp, Labeo rohita. The 96 h LC50 value of potassium dichromate estimated was 118 mg L(-1) by probit analysis using SPSS (version 16.0) software. Based on 96 h LC50 value, three sublethal test concentrations of potassium dichromate (29.5, 59.0 and 88.5 mg L(-)(1)) were selected and specimens were exposed in vivo to these test concentrations for 96 h. The mutagenic and genotoxic effects of potassium dichromate were evaluated in gill and blood cells using micronucleus (MN) test and comet assay. In general, significant (p < 0.05) effects due to the concentrations and the exposure durations were observed in exposed specimens. The MN induction was highest at 96 h at all the test concentrations in the peripheral blood. A similar trend was observed for the DNA damage, measured in terms of percentage of tail DNA, in erythrocyte and gill cells. The study indicated hazardous effect of the hexavalent chromium to fish and other aquatic organisms and indirectly to human beings.

In situ assessment of a neotropical fish to evaluate pollution in a river receiving agricultural and urban wastewater.

We aimed to assess the quality of a midsize river that receives agricultural and urban wastewater. Nuclear abnormalities (NA), comet assays of blood and gills, and gill histopathology were evaluated in fish Astyanax aff. paranae during the summer and winter 2011 at three sites in Paraná State, Brazil: (1) a biological reserve (Rebio-reference area); (2) an agricultural site; (3) a downstream site that accumulates agricultural and urban effluents. We found the highest effects of pollutants in fish at the downstream site during the summer. The agricultural site showed an intermediate damage rate, and fish at Rebio generally had the least damage, with the exception of NA. Despite conflicting results from the biomarkers used, we observed an increase in damage associated with the accumulation of pollutants. Pesticides are probable xenobiotics in the agricultural area. Additionally, metals and substances such as pharmaceuticals and ammonia may be present at the downstream site.

Assessment of the state of the gibel carp Carassius auratus gibelio in the Amur River Basin: heavy-metal and arsenic concentrations and histopathology of internal organs.

This study describes the concentrations of heavy metals and arsenic (As) and the basic histopathological changes in the internal organs of gibel carp Carassius auratus gibelio from five sites of the Amur River basin. Gibel carp from Sindinskaya Passage had the highest liver concentrations of zinc (Zn) (31.95 ± 13.443), copper (Cu) (12.52 ± 5.746), manganese (9.22 ± 8.121), and cadmium (0.37 ± 0.660 mg/kg wet weight [ww]) compared with fish captured from the Bol'shoi Ussuriiskii Island area and Kadi Lake; however, concentrations of nickel (0.22 ± 0.156 mg/kg ww) were not significantly different, and concentrations of lead (0.19 ± 0.121 mg/kg ww) were higher than those in fish from Kadi Lake. Mean concentrations of metals and As in muscles were lower than Russia's recommended limits for food products; however, concentrations of Cu, Zn, and Hg in individual fish were greater than the limit. Kidney disease was detected in 100% of sampled carp. Kidney disease was characterized by the formation of numerous granulomas in kidney tissues between the renal tubules. The degree of granulomatosis varied among sites. Granulomatous kidney disease in gibel carp is widespread in many reservoirs of the lower Amur River basin. The following histopathological changes were detected in liver: vacuolization of hepatocytes, hypertrophy of multiple hepatocytes, binuclearity, presence of numerous irregularly shaped nuclei in hepatocytes, karyopyknosis, diffuse necrosis of hepatocytes (in some cases focal), and edema. Necrotic changes in hepatocytes, which are important indices of the toxic effect of pollutants, were found in the majority of investigated carp from the lower Amur River basin. Some fish had simultaneous pathological alterations in multiple organs.

Assessment of the acute toxicity of the organochlorine pesticide endosulfan in Cichlasoma dimerus (Teleostei, Perciformes).

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.