Integrated use of histological and ultrastructural biomarkers in Mugil cephalus for assessing heavy metal pollution in Ennore estuary, Chennai

Rethinking Urban Water Management Through Drivers-Pressures-States-Impacts-Responses Framework Application in Chennai, India

Cities suffering water scarcity are projected to increase in the following decades. However, the application of standardized indicator frameworks for assessing urban water resource management problems is on an early stage. India is expected to have the highest urban population facing water scarcity in the world by 2050. In this study, the authors assess how the Drivers-Pressures-States-Impacts-Responses framework, a causal framework adopted by the European Environment Agency, can contribute to evaluate water management challenges in cities and apply it to Chennai, India´s fourth-largest urban agglomeration. The framework proved to be a helpful tool for the evaluation of water management challenges in cities by disentangling relationships between environmental indicators and structuring dispersed data that allows a better understanding for policymakers. The main drivers identified in Chennai were population growth and economic development which generated impacts such as loss of aquatic ecosystems, low water table, low water quality, and reduction of biodiversity and human health. As a response, better urban planning, projects for new water infrastructure, and water bodies restoration have been implemented. Nevertheless, Chennai keeps facing difficulties to achieve proper water management. The severe hit of the COVID-19 pandemic on the Indian economy and its future management will be key for achievements related to water management.

Heavy metal pollution causes mass mortality of fish in a tropical estuary in the southwestern Bay of Bengal

A massive fish mortality of the major species, viz., Mugil cephalus, Chanos chanos, and Oreochromis mossambicus, occurred on November 27, 2017 in the Adyar estuary. This catastrophe followed a spell of heavy rainfall and flash floods. A detailed study of water quality parameters (pH, water temperature, salinity, total suspended matter, dissolved oxygen, biochemical oxygen demand, and nutrients) and heavy metals, i.e., chromium (Cr), copper (Cu), cadmium (Cd), nickel (Ni), lead (Pb), and zinc (Zn), in the sediment and fish tissues were analyzed. Pollution indices like the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), potential ecological risk index (PERI), and biota sediment accumulation factor (BSAF) were used to measure heavy metals. The pollution indices revealed that metals were significantly enriched in the sediments. The Igeo indicates that there was moderate contamination by Cd (2.27-3.25), whereas CF shows high contamination by Cd (7.22-9.72) and moderate contamination by Pb (2.5-3.25). The PLI (1.04-1.13) suggests that heavy metal contamination of sediments has occurred. Results showed that high concentrations of the toxic metals Pb and Cd were found in the sediment as well as in fish tissues. Length and weight of fish are significantly correlated (r2 = 0.98, p < 0.05). The study revealed that the mass fish kill was due to impulsive changes in the water quality and heavy metal pollution from untreated urban sewage discharges in this region.

The EU Interreg Project "GEREMIA" on waste management for the improvement of port waters: results on monitoring the health status of fish as bioindicator

Highly anthropized areas as ports represent complex scenarios that require accurate monitoring plans aimed to address the environmental status. In this context, the activities of the EU Interreg Project "GEstione dei REflui per il MIglioramento delle Acque portuali (GEREMIA)" were focused on comparing sites differently affected by human presence, as the Port of Genoa and the natural area of the S'Ena Arrubia fishpond: a panel of analyses was carried out on Mugilidae fish sampled in these two areas, aimed to address trace metal accumulation in the liver, gills, and muscle, as well as cytochrome P450 (CYP450) induction in liver and biliary polycyclic aromatic hydrocarbon (PAH) metabolites, and histopathological alterations in the liver and gills. Chemical analyses in the liver, gills, and muscle of specimens collected in the port area showed an overall higher degree of trace metal contamination compared to the natural fishpond, and similar results were obtained in terms of CYP450 induction and biliary PAH metabolites, suggesting a higher exposure to organic compounds. In addition, histopathological analyses revealed a significant alteration and then a loss of functionality of liver and gill tissue in individuals from the port. Overall, this study describes the complex environmental pollution scenario in the Port of Genoa, confirming the importance of using multidisciplinary approaches and different types of analyses to address both the presence and the effects of contaminants in marine environments.

Tissue-specific accumulation, depuration and histopathological effects of 3,6-dichlorocarbazole and 2,7-dibromocarbazole in adult zebrafish (Danio rerio)

Although polyhalogenated carbazoles have been detected with increasing frequency in aquatic ecosystems, their bioaccumulation in fish and corresponding pathological effects related to bioaccumulation are still unclear. Here, we investigated the tissue-specific accumulation, depuration, and histopathological effects of two typical PHCZs, 3,6-dichlorocarbazole (36-CCZ) and 2,7-dibromocarbazole (27-BCZ), in adult zebrafish at three levels (0, 0.15 μg/L (5 × environmentally relevant level), and 50 μg/L (1/10 LC50). The lowest concentrations of 36-CCZ (1.2 μg/g ww) and 27-BCZ (1.4 μg/g ww) were observed in muscle, and the greatest concentrations of 36-CCZ (3.6 μg/g ww) and 27-BCZ (4 μg/g ww) were detected in intestine among the tested tissues. BCFww of 36-CCZ and 27-BCZ in zebrafish ranged from 172.9 (muscle) to 606.6 (intestine) and 285.2 (muscle) to 987.5 (intestine), respectively, indicating that both 36-CCZ and 27-BCZ have high potential of bioaccumulation in aquatic system. The 0.15 μg/L level of 36-CCZ or 27-BCZ caused lipid accumulation in liver, while 50 μg/L of 36-CCZ or 27-BCZ induced liver lesions such as fibrous septa, cytolysis, and nuclear dissolution. Brain damage such as multinucleated cells and nuclear solidification were only observed at 50 μg/L of 27-BCZ. This study provided valuable information in assessing the health and ecological risks of 36-CCZ and 27-BCZ.

Erythrocyte Recovery in Oreochromis niloticus Fish Exposed to Urban Effluents

Urban activities pollute aquatic ecosystems, and the integrity of organisms such as fish. The use of cytological techniques, such as the analysis of blood cellular integrity using the Micronucleus test, can help detect mutagenic damage as a result to urban effluents exposure. In this context, this study aimed to evaluate the frequency of micronucleus and other nuclear abnormalities in Oreochromis niloticus fish environmentally exposed to urban effluents in relation to their erythrocyte recovery capacity when exposed to clean water (30 and 45 days). The results indicated high copper, dissolved iron, nickel, and thermotolerant coliform levels in the urban stream. There was no difference in the frequency of micronuclei. In contrast, cells with nuclear nuclei, binucleates, kidney-shaped nuclei, notched nuclei, lobed nuclei, and segmented nuclei decreased according to the time the fish were exposed to clean water. When exposed to clean water, we conclude that urban fish recover from genotoxic and cytotoxic damage.

Bioaccumulation and human health risk assessment of some heavy metals in sediments, Sparus aurata and Salicornia europaea in Güllük Lagoon, the south of Aegean Sea

In the current study, it was aimed to determine the sediment in Sparus aurata (Linnaeus 1758) tissues and Salicornia europaea L. Cu, Zn Fe, Hg, Cd, Pb and Mn concentration distributions in Güllük Lagoon which is located in the south of Aegean Sea and under the influence of anthropogenic activities by means of metal pollution and health indices and to investigate the effects of these metals on public health. The concentration range of Cu, Zn, Fe, Hg, Cd, Pb and Mn in sediment samples was determined as 12.16-26.00, 1.62-2.03, 7.77-8.36, 7.52-16.15, 0.071-0.40, 7.99-13.74 and 12.11-12.63 mg kg^-1, respectively. Cu and Hg concentrations in sediment were found to be higher than sediment quality guidelines standards. In addition, according to the enrichment factor (EF), Hg, Cd and Cu were found to show above moderate enrichment. Cu, Zn, Fe, Hg, Cd and Mn concentrations in S. aurata muscle tissue were 1.31 ± 2.30, 1.01 ± 0.24, 3.43 ± 0.75, 2.79 ± 0.85, 0.01 ± 0.01 and 1.80 ± 1.12 mg kg^-1, respectively. S. europaea heavy metals (HMs) concentrations were determined as Cu = 10.97 ± 3.20, Zn = 0.74 ± 0.62, Fe = 5.69 ± 0.22, Hg = 9.62 ± 8.84, Cd = 0.53 ± 0.33, Pb = 0.22 ± 0.26 and Mn = 8.61 ± 0.14 mg kg^-1. It was seen that Hg in S. aurata muscle tissue and Hg in S. europaea concentrations exceeded the limit values determined for consumption purposes. Target hazard quotient (THQ) and total target hazard quotient (TTHQ) values were found to be < 1 for S. aurata and S. europaea. When all these results were considered, it was determined that the metals that could pose a potential ecological and health risk were Hg, Cd and Cu in the study area.

Antimony accumulation in zebrafish (Danio rerio) and its effect on genotoxicity, histopathology, and ultrastructure

Antimony (Sb) is a toxic metal in aquatic ecosystems. In this study, the accumulation of aqueous Sb in the liver, brain, gills and muscle of zebrafish (Danio rerio) and its effect on genotoxicity, histopathology and ultrastructure alterations were evaluated. The fishes were exposed to different concentrations (0, 8.29, 16.58, 33.16 mg L^-1) of aqueous Sb for 18 days. The results showed that the order of Sb accumulation in different tissues was liver > gill > muscle > brain, and the accumulation increased with increasing Sb stress concentration. The mRNA expression levels of Nrf2, Cu/Zn-SOD, Mn-SOD, CAT and GPx genes showed different trends. In addition, significant histopathology and ultrastructure alterations were observed in the liver and gills exposed to Sb. Sb could accumulate in different tissues of zebrafish, inducing the expression of oxidative stress genes and activating antioxidant defense systems. Histological and ultrastructural changes could be used as valid biomarkers for the assessment of aqueous Sb contamination.

Gill Histopathological Biomarkers in Fish Exposed to Trace Metals in the Todos os Santos Bay, Brazil

Histopathologies are widely recognized as biomarkers of environmental pollution. In this sense, we evaluated the putative relationship of gill histopathologies and distinct ecological impacts in two regions of Todos os Santos Bay (BTS), Brazil, the largest bay in Northeastern Brazil, South Atlantic. We compared the presence and concentration of metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn) in water, sediments, and gills and gill histopathologies of a demersal fish (Diapterus rhombeus) and a benthic fish (Ogcocephalus vespertilio). As expected, fish and sediment samples from historically contaminated areas (Aratu) showed more remarkable traces of metals than apparently low-impact areas (Jaguaripe). Likewise, the DTC (degree of tissue change) index and the volume densities were higher in fish caught in Aratu. In addition, the Diapterus rhombeus species showed more potential than Ogcocephalus vespertilio for risk assessment as it showed more responses to the environment reflected on more histopathologies. These data support the effectiveness of incorporating functional gill morphology to monitor impacts on estuarine biota that can be used as a reference to improve the management of ecosystems and prevent harm to human health.

Gill Histopathology as a Biomarker for Discriminating Seasonal Variations in Water Quality

Histopathological alterations in various fish organs have a pronounced value in aquatic toxicology and are widely used in environmental monitoring. The aim of this study was to evaluate whether histopathological alterations in fish gills can discriminate seasonal variations in environmental conditions within the same aquatic ecosystem, and if so, which alterations contributed the most to seasonal differentiation. Microscopic examination of common bream Abramis brama gills displayed various alterations in gill structure, including epithelial hypertrophy, hyperplasia, mucous and chloride cell alterations, epithelial lifting, necrosis, hyperemia and aneurism. These alterations were subsequently quantified by a semi-quantitative analysis in order to detect differences in the intensity of the mentioned alterations. Epithelial hypertrophy, hyperplasia, epithelial lifting and necrosis varied significantly between seasons with only necrosis being significantly higher in the first season. Discriminant canonical analysis displayed that epithelial hyperplasia, mucous cell alterations, epithelial lifting and necrosis contributed the most to discrimination between seasons. Overall, this study demonstrates that histopathological biomarkers in fish gills can be used in discriminating seasonal variations in water quality within the same aquatic ecosystem.

Histopathological alterations in gills, liver, kidney and muscles of Ictalurus punctatus collected from pollutes areas of River

Abstract Untreated sewage and industrial wastes from Faisalabad city are disposed to River Chenab through Chakbandi Main Drain (CMD). The present project is planned to investigate the effects of this freshwater pollution on the body of fish Ictalurus punctatus. The specimens of this fish species were collected upstream and downstream of the entrance of CMD into River Chenab. Fish gills, liver, kidney and muscles from dorsolateral regions of fish were subjected to histopathology. Farmed fish and fish from upstream areas were used as control. Fish collected from polluted experimental sites showed significant damage in selected organs. Gill tissues showed an abnormality in the form of an uplifting of the primary epithelium, fusion, vacuolation, hypertrophy, and necrosis. While liver tissues subjected to hepatocytes degeneration, necrosis, mitochondrial granular hepatocyte, and sinusoids dilation. Kidney tissues indicated increased bowmen space and constricted glomerulus and degenerated nephrons. Edema, necrosis, and atrophy were observed in muscle tissues of fish from polluted areas. Fish from the upstream area showed fused gill lamellae, inflammatory cell infiltration, hypertrophy and vacuolation in hepatocytes. Kidney tissues indicated the presence of nuclear tubular cells, destructive renal tubules, hemorrhage, and necrosis at tubular epithelium. Intra myofibril spaces were also observed in muscles. Specimens of control fish indicated no variation in gills, liver, kidney, and muscles. The present study revealed a strong correlation between the degree of tissue damage and environmental contamination. Present findings also compel global warnings to protect our water bodies and fish to rescue the human population.

Metabolite profiling, histological and oxidative stress responses in the grey mullet, Mugil cephalus exposed to the environmentally relevant concentrations of the heavy metal, Pb (NO3)2

In this study, a metabolomics approach was applied to investigate the metabolic responses of grey mullet, Mugil cephalus to toxicity induced by heavy metal, Pb (NO3)₂. In addition, the study was followed by assessing the peroxidation index and histology of liver as supplementary data. Pb (NO3)₂ exposure affected the plasma metabolome, especially four group metabolites including amino acids, methylated metabolites, energetic metabolites and citric acid intermediates. Pb (NO3)₂ in medium and high concentrations (15 and 25 μg/l) increased the levels of plasma amino acids compared to control (P < 0.01). In contrast, Pb (NO3)₂ decreased the plasma levels of methylated metabolites (P < 0.01). The ketogenic metabolites and glycerol levels significantly elevated in fish exposed to 25 μg/l Pb (NO3)₂ (P < 0.01). The plasma glucose levels increased in treatment, 5 μg/l Pb (NO3)₂ and after a decline in treatment 15 μg/l Pb (NO3)₂ elevated again in treatment 25 μg/l Pb (NO3)₂ (P < 0.01).The plasma levels of lactate significantly increased in fish exposed to 5 and 15 μg/l Pb (NO3)₂ and then declined to initial levels in treatment, 25 μg/l Pb (NO3)₂ (P < 0.01). The plasma levels of TCA cycle intermediates significantly elevated in treatments 15 and 25 μg/l Pb (NO3)₂ (P < 0.01). As a biomarker of oxidative stress, the plasma levels of malondialdehyde (MDA) showed significant increases in Pb (NO3)₂ exposed fish (P < 0.01). During exposure period, wide ranges of liver tissue damages were also observed in Pb (NO3)₂ exposed fish. In conclusion, exposure to Pb (NO3)₂ affected the metabolome content of blood in grey mullet, mainly through inducing the biochemical pathways related to the metabolism of the amino acids, energetic metabolites and methylated metabolites. Our results may help to understand the effects of heavy metals on fish hematology from a molecular point of view.

Hepatic Toxicity in Etroplus suratensis (Bloch 1790): An Economically Important Edible Fish in Vembanad Fresh Water Lake, Kerala, India

Fish consumption from contaminated water-bodies is a serious health issue. This study conducted to reveal the presence of heavy metals and bisphenols in Vembanad lake, an exploiting tourist spot in Kerala, receiving untreated agricultural, domestic, municipal, and industrial effluents. We evaluated aquatic contaminant impact on hepatic stress markers in Etroplus suratensis from fragile Vembanad lake. The significant difference in water physiochemical parameters, the concentration of heavy metals, and bisphenols (BPA and BPS) were studied. Hepatic tissue of E. suratensis inhabited in lake featured with high iron (11.29 ± 0.39 ppm) and BPA (0.02412 ± 0.0031 µg/mL) content along with an increased hepatic stress marker and distorted hepatic structure. The study highlights the presence of high iron and BPA in edible fish. The study recommends monitoring of physiochemical characters of freshwater lakes is essential for better survival of freshwater flora and fauna.

De novo assembly and characterization of the liver transcriptome of Mugil incilis (lisa) using next generation sequencing

Mugil incilis (lisa) is an important commercial fish species in many countries, living along the coasts of the western Atlantic Ocean. It has been used as a model organism for environmental monitoring and ecotoxicological investigations. Nevertheless, available genomic and transcriptomic information for this organism is extremely deficient. The aim of this study was to characterize M. incilis hepatic transcriptome using Illumina paired-end sequencing. A total of 32,082,124 RNA-Seq read pairs were generated utilizing the HiSeq platform and subsequently cleaned and assembled into 93,912 contigs (N50 = 2,019 bp). The analysis of species distribution revealed that M. incilis contigs had the highest number of hits to Stegastes partitus (13.4%). Using a sequence similarity search against the public databases GO and KEGG, a total of 7,301 and 16,967 contigs were annotated, respectively. KEGG database showed genes related to environmental information, metabolism and organismal system pathways were highly annotated. Complete or partial coding DNA sequences for several candidate genes associated with stress responses/detoxification of xenobiotics, as well as housekeeping genes, were employed to design primers that were successfully tested and validated by RT-qPCR. This study presents the first transcriptome resources for Mugil incilis and provides basic information for the development of genomic tools, such as the identification of RNA markers, useful to analyze environmental impacts on this fish Caribbean species.

Effect of sublethal gradient concentrations of nickel on postlarvae of Penaeus monodon, Perna viridis and Terapon jarbua: Enzyme activities and histopathological changes

The present study evaluates the enzyme activities and histopathological changes in the post larvae (PL) of shrimp (Penaeus monodon), green mussel (Perna viridis) and fingerlings of crescent perch (Terapon jarbua) exposed to sublethal gradient concentrations of Nickel (Ni). The median lethal concentration (LC₅₀) values were 2.49, 66.03 and 43.92 mg Ni L^-1 derived for the PL of shrimp, green mussel and fish fingerlings respectively. No Observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values of the PL of shrimp were 46.5, 73.0 and 58.3 μg Ni L^-1 derived for the 21-d survival endpoint. The NOEC, LOEC and chronic values for the 30-d survival endpoint of the green mussels and fish fingerlings were 4.6, 6.32, 5.4 and 1.95, 2.6, 2.25 mg Ni L^-1 respectively. The isoforms of esterase, superoxide dismutase and malate dehydrogenase activities in the whole body tissues of test organisms were studied by native polyacrylamide gel electrophoresis after exposure to Ni. Histological examination of compound eye sections of shrimp revealed deformation, compression, fusion and detachement in the corneal cells from the corneal facet of the ommatidia indicating cellular anomalies due to Ni toxicity. Gill sections of the green mussel witnessed reduced haemolymph in sinuses of gill filaments, degenerative changes in interfilamentous junction and necrosis of frontal ciliated epithelial cells with vacuoles after exposure to Ni. Nickel affects the vision of shrimp and fish fingerlings, gills and byssus of green mussels.

Mass mortality of fish and water quality assessment in the tropical Adyar estuary, South India

Mass mortality of fishes was reported at the Adyar estuary, South India, during November 2017. The probable reasons for fish mortality are analyzed in this paper. Critical assessments on water quality parameters including the metal concentrations, nutrients, and histology of gills and liver of fish (Mugil cephalus) isolated from the impact zone were performed. Among the metals observed, chromium showed levels (3.64 ± 0.001 mg L^-1) much above the average permissible limits (0.1 mg L^-1). The measured values of physico-chemical parameters in the impact zone are as follows: dissolved oxygen 4.7 ± 0.22 mg L^-1, total alkalinity 132 ± 4 CaCO₃ mg L^-1, salinity 5.3 ± 0.3 PSU, temperature 27.8 ± 0.16 °C, nitrate, 1.66 ± 0.48 mg L^-1, nitrite 0.01 ± 0.0008 mg L^-1, ammonia 0.03 ± 0.001 mg L^-1, phosphate 1.52 ± 0.002 mg L^-1, and silicate 13.85 ± 3.1 mg L^-1. The low salinity could have escalated the toxicity of the metal. In addition, histology of gills and liver showed cellular necrosis, epithelial lifting, hyperplasia, edema, mucous cell proliferation in the gills, cytoplasmic vacuolation of hepatocytes, and degeneration of liver which reveal that chromium toxicity is the most probable cause for mass mortality.

Modulation of mitochondrial functions by xenobiotic-induced microRNA: From environmental sentinel organisms to mammals

Mitochondria play a crucial role in energetic metabolism, signaling pathways, and overall cell viability. They are in the first line in facing cellular energy requirements in stress conditions, such as in response to xenobiotic exposure. Recently, a novel regulatory key role of microRNAs (miRNAs) in important signaling pathways in mitochondria has been proposed. Consequently, alteration in miRNAs expression by xenobiotics could outcome into mitochondrial dysfunction, reactive oxygen species overexpression, and liberation of apoptosis or necrosis activating proteins. The aim of this review is to show the highlights about mitochondria-associated miRNAs in cellular processes exposed to xenobiotic stress in different cell types involved in detoxification processes or sensitive to environmental hazards in marine sentinel organisms and mammals.

Metals and arsenic in fish from a Ramsar site under past and present human pressures: Consumption risk factors to the local population

The risk of metals and As in seafood for traditional populations living in a Marine Protected Areas (MPA) is seldom assessed, although the risk of human exposure to contaminants is one of the indicators associated with the socioeconomic goals of MPAs. The current study aimed to estimate the potential risk of some metals (Cd, Pb, and Zn) and arsenic (As) for human health through the ingestion of fish locally harvested in a Ramsar site, the Cananéia-Iguape-Peruíbe Environmental Protected Area (APA-CIP). Previous studies showed environmental impacts in this area due to former mining activities and urbanization. Cathorops spixii, a catfish largely consumed by the local population, was collected along the estuary in three seasons with different rain regimes. Metals and As loads in muscle tissue were quantified and it was estimated (i) the target hazard quotient (THQ) and (ii) the daily intake (EDI) for metals and As, (iii) the cancer risk (CRisk) only for As, and (iv) the number of eligible meals per month. Cd, Pb, and As were found at concentrations above action levels for human consumption. Depending on the level of exposure of the local population, the consumption of C. spixii may pose risk to human health. Highest THQs were estimated for fish collected in sites closer to the main contamination sources in the APA-CIP, i.e. the mouth of Ribeira de Iguape River (P1) and the city of Cananéia (P4, P5, and P6). Arsenic showed high levels of cancer risk, although restricted to the area close to the city. The exposure of the local population to metal and As contaminated seafood cannot be disregarded in environmental studies and management of the APA-CIP.

Multivariate and integrative approach to analyze multiple biomarkers in ecotoxicology: A field study in Neotropical region

Aquatic pollution has dramatically worsened in developing countries, due to the discharge of a mixture of pollutants into water bodies, to the lack of stringent laws, and the inadequate treatment of effluents. In this study, the Neotropical fish Astyanax aff. paranae was sampled from three sites with different pollution levels: 1) a Biological Reserve (Rebio), protected by the Brazilian government; 2) an agricultural area in one of the most productive regions of Brazil, upstream of an urban zone; and 3) a site downstream from urban zone, characterized by the influx of different effluents, including wastes from industry, a sewer treatment plant, and agricultural areas. We assess biomarkers at multiple levels, such as the comet assay, hepatic histopathological analysis, brain and muscle acetylcholinesterase (AChE) and the hepatic enzymes glutathione-S-transferase (GST), catalase (CAT), and lipoperoxidation (LPO), during winter and summer. The interpretation of field results is always a very complex operation, since many factors can influence the variables analyzed in uncontrollable conditions. For this reason, we apply an integrative multivariate analysis. The results showed that the environmental risk of the three sites was significantly different. We can see a gradient in data distribution in discriminant analysis: separating, from one side, the fish of Rebio; in the middle are the fish from agricultural area and, in the other side are the animals from downstream site. Overall, the biomarkers responses were more greatly altered in the downstream site, whereas fish from the agricultural area showed an intermediate level of damage. The greatest changes were likely caused by agriculture, industrial chemical effluents and ineffective sewage treatments, in a synergic interaction in downstream site. In conclusion, the use of multiple biomarkers at different response levels to assess the toxic effects of mixed pollutants in a natural aquatic environment is an important tool for monitoring polluted regions.

Cadmium and lead concentrations in hepatic and muscle tissue of demersal fish from three lagoon systems (SE Gulf of California)

We determined the levels of Cd and Pb in liver and muscle of demersal fish from three lagoon systems (Urías, Huizache, and Teacapán) in the SE Gulf of California with the purpose of comparing the studied metals in fish from the three ecosystems and to assess the potential human health risk. Considering the number of individuals, the sequence of fish abundance was Teacapán > Huizache > Urías. Length and size at maturity of collected species showed that 76.5% of the individuals were juveniles. Overall, Cd and Pb were more accumulated in liver than in muscle. After multivariate analyses, considering fish tissue and locality, Cd and Pb levels were different (p < 0.05) between fish from Teacapán and Huizache. In general, the hazard quotients (HQs) of Pb were higher than the corresponding values of Cd; the highest HQ for Cd (0.0051) corresponded to Mugil curema, and the highest HQ for Pb (0.0099) was estimated in Diapterus peruvianus. With respect to the hazard index (accumulative risk from Cd and Pb), the most elevated value (HI = 0.0124) was estimated for Pomadasys macracanthus. Estimated HI does not represent a health risk at the consumption rates of the Mexican population.

Total mercury concentrations in white and striped Mullet (Mugil curema and M. cephalus) from a coastal lagoon in the SE Gulf of California

The White and Striped mullets (Mugil curema and M. cephalus) are highly abundant and commercially important estuarine fish in northwest (NW) Mexico. Because of their feeding habits and habitat, they are likely to accumulate mercury (Hg) in their muscle and liver. The objectives of this study were to determine total Hg distribution in the tissues of interest, to correlate Hg levels between tissues and with length and weight of fish, to estimate the percentage weekly intake (PWI) of total Hg and methyl Hg (MeHg) through consumption of both mullet species, and to compare total Hg levels with mullets from other areas. The highest total Hg concentration (1.031 µg g^-1 dry weight) was measured in liver of White mullet. In both species, the order of averaged Hg concentrations (M. curema liver 0.272, muscle 0.184; M. cephalus liver 0.211, muscle 0.129 µg g^-1 dry weight) were liver>muscle. Correlations of Hg in muscle and liver with total weight of M. curema were significant. In M. cephalus, Hg levels in liver were significantly correlated with total length and weight. The PWI of THg (<4%) and MeHg (<10%) were not elevated for both species. Concentration of Hg in the studied mullets was comparable to levels in similar species from Mexican waters but lower than results in mugilids from other coastal areas.

Integrated biomarker response in catfish Hypostomus ancistroides by multivariate analysis in the Pirapó River, southern Brazil

Aquatic pollutants produce multiple consequences in organisms, populations, communities and ecosystems, affecting the function of organs, reproductive state, population size, species survival and even biodiversity. In order to monitor the health of aquatic organisms, biomarkers have been used as effective tools in environmental risk assessment. The aim of this study is to evaluate, through a multivariate and integrative analysis, the response of the native species Hypostomus ancistroides over a pollution gradient in the main water supply body of northwestern Paraná state (Brazil). The condition factor, micronucleus test and erythrocyte nuclear abnormalities (ENA), comet assay, measurement of the cerebral and muscular enzyme acetylcholinesterase (AChE), and histopathological analysis of liver and gill were evaluated in fishes from three sites of the Pirapó River during the dry and rainy seasons. The multivariate general result showed that the interaction between the seasons and the sites was significant: there are variations in the rates of alterations in the biological parameters, depending on the time of year researched at each site. In general, the best results were observed for the site nearest the spring, and alterations in the parameters at the intermediate and downstream sites. In sum, the results of this study showed the necessity of a multivariate analysis, evaluating several biological parameters, to obtain an integrated response to the effects of the environmental pollutants on the organisms.

Ultrastructural, ssrDNA sequencing of Myxobolus prochilodus and Myxobolus porofilus and details of the interaction with the host Prochilodus lineatus

Myxobolus prochilodus and Myxobolus porofilus are parasites of Prochilodus lineatus, an economically important South American fish found in La Plata and Paraiba do Sul river basins. This study focusing on parasite-host interaction provides an ultrastructural and phylogenetic analysis, the latter based on ssrDNA sequencing of these parasites respectively infecting the gill filaments and fins of P. lineatus taken from the Mogi Guaçu River, São Paulo, Brazil. A total of 13 adult specimens were examined in this study. The prevalence of infection was 7.69 % for M. prochilodus and 15.38 % for M. porofilus. Phylogenetic analysis showed M. prochilodus and M. porofilus clustered in a subclade composed of parasites of the Prochilodontidae family. In M. prochilodus infecting gill filaments, where cellular degeneration in the epithelium was observed, the plasmodia were surrounded by a capsule composed of layers of fibrocyte-like cells, with cellular projections joined to the projections of other fibrocyte-like cells by desmosomes, and more externally typical fibroblast layers. Some granular leukocytes were seen interspersed among these layers. In M. porofilus infecting the fins, the capsule of connective tissue was represented only by loosely arranged collagen fibers, and no granular leucocytes were observed. Finally, several unusual vacuoles with filamentous content and some characteristics usually described as degenerative alterations, as myelin figure, were noted in plasmodia and pansporoblasts of both myxosporean species. The possible influence of inflammatory response and xenobiotics was considered to be the explanation for the alterations observed in Myxobolus species and its host.

Mercury-Pollution Induction of Intracellular Lipid Accumulation and Lysosomal Compartment Amplification in the Benthic Foraminifer Ammonia parkinsoniana

Heavy metals such as mercury (Hg) pose a significant health hazard through bioaccumulation and biomagnification. By penetrating cell membranes, heavy metal ions may lead to pathological conditions. Here we examined the responses of Ammonia parkinsoniana, a benthic foraminiferan, to different concentrations of Hg in the artificial sea water. Confocal images of untreated and treated specimens using fluorescent probes (Nile Red and Acridine Orange) provided an opportunity for visualizing the intracellular lipid accumulation and acidic compartment regulation. With increased Hg over time, we observed an increased number of lipid droplets, which may have acted as a detoxifying organelle where Hg is sequestered and biologically inactivated. Further, Hg seems to promote the proliferation of lysosomes both in terms of number and dimension that, at the highest level of Hg, resulted in cell death. We report, for the first time, the presence of Hg within the foraminiferal cell: at the basal part of pores, in the organic linings of the foramen/septa, and as cytoplasmic accumulations.

Environmental safety level of lead (Pb) pertaining to toxic effects on grey mullet (Mugil cephalus) and tiger perch (Terapon jarbua)

Acute and chronic bioassay toxicity test of Lead (Pb) in Grey Mullet (Mugil cephalus), and Tiger perch (Terapon jarbua) was conducted. LC50 values (Lethal Concentration) from acute tests and chronic values were calculated by the geometric mean of the No-Observed-Effect Concentration (NOEC) and the Lowest-Observed-Effect Concentration (LOEC) in a study period of 30 days. This research was conducted to evaluate the quantitative relationship between toxicity test statistics and correlation between toxicant and the organisms exposed. Three test average LC50 was analyzed for 24, 48, 72, and 96 h and the 96 h average LC50 of M. cephalus and T. jarbua is 2.57 ± 0.47 and 2.99 ± 0.23 mg/L of Pb, respectively. Significant correlation is observed with the increased time duration and exposure concentration. The NOEC and LOEC values were calculated based on survival of test organisms for M. cephalus and T. jarbua and the values are 0.014 and 0.029 and 0.011 and 0.022 mg/L, respectively. The chronic value is found to be 0.011 mg/L for M. cephalus and 0.021 mg/L for T. jarbua. The intensity of biochemical and histological alterations increased gradually with increased Pb concentration and the exposure time. Toxicity testing is the primary step to determine the water quality safe limit on marine organisms. The outcome of the study indicates that the sensitivity of juvenile organisms to Pb, persistence of toxic effects and biomarkers as a tool capable of revealing the toxic effects of heavy metals on the environment and aquatic biota.

Evaluation of impacted Brazilian estuaries using the native oyster Crassostrea rhizophorae: Branchial carbonic anhydrase as a biomarker

In this study, we investigated the use of branchial carbonic anhydrase activity in a sessile filter feeding species, the oyster Crassostrea rhizophorae, as a biomarker. The oysters were collected in three human impacted Brazilian estuaries, following a crescent latitudinal gradient: in Pernambuco state (Itamaracá), in Espírito Santo state (Piraquê), and in Paraná state (Paranaguá), in August/2003 (Winter in the southern hemisphere) and February/2004 (Summer). Three sites were chosen in each estuary for oyster sampling: Reference (R), Contaminated 1 (C1, close to industrial/harbor contamination), and Contaminated 2 (C2, near to sewage discharges). Comparing to values in oysters sampled in reference sites, there was apparent inhibition in carbonic anhydrase activity (CAA) in gills of oysters from C1 of Itamaracá and from C2 of Piraquê, both cases in Summer. On the other hand, increased CAA was noted in C2 oysters of Itamaracá in winter, and of Paranaguá, in both seasons. Branchial CAA in C. rhizophorae was thus very responsive to coastal contamination. Data are consistent with its usefulness as a supporting biomarker for inexpensive and rapid analysis in the assessment of estuaries using a sessile osmoconformer species, but preferably allied to other biomarkers and with knowledge on the suite of contaminants present.

Ultrastructural effects on gill tissues induced in red tilapia Oreochromis sp. by a waterborne lead exposure

Experiments on hybrid red tilapia Oreochromis sp. were conducted to assess histopathological effects induced in gill tissues of 96 h exposure to waterborne lead (5.5 mg/L). These tissues were investigated by light and scanning electron microscopy. Results showed that structural design of gill tissues was noticeably disrupted. Major symptoms were changes of epithelial cells, fusion in adjacent secondary lamellae, hypertrophy and hyperplasia of chloride cells and coagulate necrosis in pavement cells with disappearance of its microridges. Electron microscopic X-ray microanalysis of fish gills exposed to sublethal lead revealed that lead accumulated on the surface of the gill lamella. This study confirmed that lead exposure incited a difference of histological impairment in fish, supporting environmental watch over aquatic systems when polluted by lead.

Application of biomarkers in Epaulet grouper (Epinephelus stoliczkae) to assess chromium pollution in the Chabahar Bay and Gulf of Oman

In the present study plasma levels of erythropoietin (EPO) hormone and kidney histological changes were assessed as biomarkers to evaluate the chromium pollution in Epaulet grouper (Epinephelus stoliczkae) obtained from different areas in Chabahar Bay and Gulf of Oman. Chemical analyses included the evaluation of chromium in the fish kidney tissue and sediment. The highest and lowest concentrations of chromium were measured in the kidney of fish and sediment collected from Konarak (47.53±1.23 and 110±1.4 μg g(-1)) and the mouth of Chabahar Bay (3.43±1.31 and 13.5±3.23 μg g(-1)), respectively. There was significant difference (P<0.05) of EPO plasma levels between Konarak, Beris and Ramin stations with the mouth of Chabahar Bay as the cleanest station. Reduction of Bowman's space, occlusion of the tubule lumen, leukocytes infiltration, melanomacrophage centers aggregation, nuclear vacuolation, nuclei hypertrophy of tubule cells, necrosis of the tubules, lifting of the tubular basement membrane and dilatation of glomerular capillaries were the most alterations observed in the kidney. The HAI values of Epaulet grouper from Konarak, Beris and Ramin stations were significantly higher than other stations (P<0.05). It was concluded that selected biomarkers as a first investigation could be useful tools to environmental biomonitoring programs.

Assessment of the health status of wild fish inhabiting a cotton basin heavily impacted by pesticides in Benin (West Africa)

To determine the impact of agricultural pesticides used in cotton cultivation on the health status of fish living in a Beninese cotton basin, we compared the reproductive and hepatic systems of fish sampled from rivers located in both contaminated and pristine conditions. Different types of biomarkers, including biometric indices (a condition factor K, a gonadosomatic index GSI, and a hepatosomatic index HSI), plasma levels of sex steroids (11-ketotestosterone 11-KT, testosterone T and estradiol-17β E2) and the histopathology of the gonads and liver, were investigated for two different trophic levels of the following two fish species: the Guinean tilapia Tilapia guineensis and the African catfish Clarias gariepinus. The fish were captured during both the rainy season (when there is heavy use of pesticides on cotton fields) and the dry season from one site, in Pendjari River (reference site), which is located outside the cotton-producing basin, and from three other sites on the Alibori River within the cotton-producing basin. Comparing fish that were sampled from contaminated (high levels of endosulfan, heptachlor and DDT and metabolites) and reference sites, the results clearly indicated that agricultural pesticides significantly decreased K and GSI while they increased HSI, regardless of the season, species and sex of the fish. These pesticides also induced a decrease in the plasma levels of 11-KT and T and increased those of E2. The histopathology of the testes revealed, in both species, a high rate of testicular oocytes, up to 50% in the African catfish, downstream of the Alibori River, which indicated estrogenic effects from the pesticides. The disruption of male spermatogenesis primarily included necrosis, fibrosis and the presence of foam cells in the lobular lumen. The histopathology of the ovaries revealed high levels of pre-ovulatory follicular atresia, impaired oogenesis, a decrease in the oocyte vitellogenic diameter and other lesions, such as fibrosis, vacuolation and melano-macrophagic centers. The histopathology of the liver revealed the presence of necrosis, hypertrophic hepatocytes, foci of vacuolation, glycogen depletion and hemosiderin. An assessment of the general health of the fish indicated that all of the sampled fish from the polluted sites were in poorer health compared with those from the reference site but that the African catfish appeared much more affected than the Guinean tilapia, regardless of the sex and season. In conclusion, the overall results indicated that agricultural pesticides significantly impair the endocrine regulation of fish living in the Beninese cotton basin and that this would most likely be one of the causes of the severe damage observed in the liver and gonads and the reduced health condition.

The application of histo-cytopathological biomarkers in the mud crab Scylla serrata (Forskal) to assess heavy metal toxicity in Pulicat Lake, Chennai

The concentrations of heavy metals and their associated structural deformities in the gills, muscles and hepatopancreas of Scylla serrata from Pulicat Lake were determined and compared with crabs live along Kovalam coast. The concentrations of metals were high in the hepatopancreas and gills of crab from Pulicat Lake, whereas, low in crab from the Kovalam coast. Data were visualized using a principal component analysis (PCA). Significant differences were found for all variables at the plot scale; however, the overall variation was relatively low for muscle tissues in both stations. The structural deformities observed in the gills, hepatopancreas and muscle was due to metal toxicity, and the degree of damage was correlated with the elevated metal concentration. The results showed significant metal accumulation and histo-cytological lesions in the crabs from Pulicat Lake. The results suggest that these biomarkers are useful for assessing the impact of metal pollution in the coastal environments.