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Aquatic organisms that inhabit coastal areas are often exposed to several contaminants. It is known that the bioaccumulation of contaminants can be amplified according to the species feeding habits and contaminant properties. As a consequence, species can experience different effects to contaminant exposure even if they inhabit the same area. The present study aimed to investigate the activities of carbonic anhydrase (CA), Ca2+-ATPase, and Mg2+-ATPase in different tissues (soft tissue, mantle, and gill) of three mollusk species (Lottia subrugosa, Stramonita brasiliensis, and Crassostrea brasiliana) with different feeding habits (herbivore, carnivore, and filter-feeder, respectively) which were sampled within a known contamination gradient at Santos Estuarine System (Southeastern Brazil). From the three enzymes tested, only CA was affected by the presence of contaminants within the contamination gradient evaluated. In general, the CA activity from the three species were lower in contaminated sites when compared to the reference site. The contrasting CA activity response observed in S. brasiliensis compared to L. subrugosa and C. brasiliana could be related to the tissue-specificity of this enzyme activity and species feeding habits (filter-feeders can accumulate more contaminants than herbivores and even carnivores). Results indicated that C. brasiliana mantle is the most suitable tissue for the use of CA analysis as a biomarker.

Oil and derivatives are essential to supply human demand for energy. Despite the significant increase in security measures to avoid accidental spills, the impacts of these pollutants to the aquatic environment are still substantial. It is therefore crucial to study and understand the main effects of these substances on the aquatic organisms and how the water chemistry can influence the bioavailability and toxicity of these compounds. This is essential information for the aquatic biodiversity and sustainability of aquaculture. This chapter addresses how environmental contamination by oil and derivatives can impair fish, mollusk, and crustacean health and, as a consequence, the productivity of aquaculture and the farmed aquatic animal quality.

Studies have shown that shell morphology and enzymatic activities in mollusks are affected by contaminants exposure. However, the correlation between enzymatic activities and the biomineralization process are not fully understood. The present study used a transplant bioassay and field sampling to evaluate shell measurements and the activities of carbonic anhydrase, Ca2+-ATPase, and Mg2+-ATPase in Lottia subrugosa sampled in Brazilian sites under different contamination levels. Results showed that, in general, shells from the reference site (Palmas) were more rounded than the ones from the contaminated site (Balsa). Effects in enzymatic activities in specimens from transplant bioassay were attributed to the known high contaminant levels present at Balsa. While the lack of enzymatic activity alterations during field sampling was attributed to physiological adaptation to contaminants exposure. Enzymatic activities were not correlated to shell biometric parameters in field sampling, indicating that these enzymes were not related to shell alterations detected in the present study.

A externalização de órgãos internos em peixes tem sido registrada ao longo do tempo na literatura científica. Grande parte dos registros está relacionada à eversão ou protrusão do estômago e/ou intestino, devido principalmente ao barotrauma. Porém uma pequena parcela dos registros é referente a diversas causas naturais. O presente estudo teve como objetivo registrar a ocorrência de um raro evento de eversão vaginal na raia anã espinhosa Psammobatis rutrum. Em 15/06/2020 três exemplares (2 fêmeas e 1 macho) foram capturados como fauna acompanhante da pesca de parelha nas proximidades da Barra de Santos SP, com profundidade média de 27 metros. Dentre eles, uma exemplar fêmea apresentava uma protrusão via abertura cloacal. Através de necropsia, avaliação comparativa e estudo das vias reprodutivas foi identificado que o órgão externalizado era a parede vaginal. Embora existam muitos registros de externalização de órgãos de Elasmobranchii, principalmente relacionados ao comportamento natural de eversão do estômago e intestino, apenas um registro deste tipo de evento foi reportado para órgão reprodutivo. Não foi possível identificar a causa da eversão vaginal, porém tal evento está associado a um quadro de prolapso pélvico, que pode ter sido intensificado por causas naturais ou devido a captura.

Many cities worldwide are established adjacent to estuaries and their catchments resulting in estuarine contamination due to intense anthropogenic activities. The aim of this study was to evaluate if fish living in an estuarine urban waterway were affected by contamination, via the measurement of a suite of biomarkers of fish health. Black bream (Acanthopagrus butcheri) were sampled in a small urban embayment and a suite of biomarkers of fish health measured. These were condition factor (CF), liver somatic index (LSI), gonadosomatic index (GSI), hepatic EROD activity, polycyclic aromatic hydrocarbon (PAH) biliary metabolites, serum sorbitol dehydrogenase (s-SDH) and branchial enzymes cytochrome C oxidase (CCO), and lactate dehydrogenase (LDH) activities. The biomarkers of exposure EROD activity, and pyrene- and B(a)P-type biliary metabolites confirmed current or recent exposure of the fish and that fish were metabolizing contaminants. Relative to a reference site, LSI was higher in fish collected in the urban inlet as was the metabolic enzyme LDH activity. CF, GSI, s-SDH, CCO, and naphthalene-type metabolites were at similar levels in the urban inlet relative to the reference site. PAH biliary metabolite ratios of high-molecular-weight to low-molecular-weight suggest that fish from the urban inlet were exposed to pyrogenic PAHs, likely from legacy contamination and road runoff entering the embayment. Similarly, the sediment PAH ratios and the freshness indices suggested legacy contamination of a pyrogenic source, likely originating from the adjacent historic gasworks site and a degree of contamination of petrogenic nature entering the inlet via storm water discharge. Biomarkers of exposure and effect confirmed that black bream collected in the Claisebrook Cove inlet, Western Australia, are currently exposed to contamination and are experiencing metabolic perturbations not observed in fish collected at a nearby reference site.

Made available in DSpace on 2018-12-11T17:07:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-02-01 Financiadora de Estudos e Projetos Here we explore the dose-dependent response of the tropical fish tambaqui (Colossoma macropomum) to intraperitoneal injection of benzo[a]pyrene (BaP) at doses of 0 (carrier control), 1, 10, 100 and 1000 μmolar BaP Kg−1 Hepatic ethoxyresorufin-O-deethylase (EROD) activity showed a bell-shaped dose-dependent response curve, where the highest injected BaP dose caused enzyme inactivation. Activities of hepatic catalase (CAT) and superoxide dismutase (SOD) increased at the highest dose relative to the carrier control group. Lipid peroxidation (LPO), serum-sorbitol dehydrogenase (s-SDH) and DNA damage in blood cells were higher for all BaP doses when compared to the carrier control group. At high dosage, the production of BaP metabolites was paralleled by induced activity of the antioxidant enzyme SOD, and high levels of DNA damage in blood cells. In a similar way, high LPO was concomitant to elevated s-SDH in the bloodstream, suggesting that lipid peroxidation caused the loss of membrane integrity and leakage of s-SDH from hepatocytes into the bloodstream. These biomarkers were also positively co-correlated. The results demonstrate the potential use of a suite of biomarkers for tambaqui living in contaminated tropical aquatic environments. In particular, we recommend the analysis of DNA damage in blood cells, as this was highly correlated with all other biomarkers. Brazilian National Institute for Research in the Amazon Laboratory of Ecophysiology and Molecular Evolution, Ave André Araújo 2936 Biosciences Institute São Paulo State University − UNESP Coastal Campus, Pça Infante Dom Henrique s/n°, P.O. Box 73601, São Vicente Department of Environment and Agriculture Curtin University, P.O. Box U1987 Biosciences Institute São Paulo State University − UNESP Coastal Campus, Pça Infante Dom Henrique s/n°, P.O. Box 73601, São Vicente

The present work aimed to investigate the effects of acute (12, 24, 48 and 96 h) and subchronic (168 and 336 h) exposure of seahorse, Hippocampus reidi to water-accommodated fraction (WAF) of diesel fuel on biotransformation parameters, antioxidant defenses and DNA integrity. In addition, a recovery experiment was performed, where the organisms remained in absence of the contaminant for 336 h, after WAF exposure for 168 h (totaling 504 h). At the end of each experimental protocol, the concentration of pyrene-, benzo(a)pyrene- and naphthalene-type metabolites in bile, hepatic activity of glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT), as well as lipid peroxidation (LPO) levels in hepatocytes, were analyzed, in addition to the DNA damage and the micronucleus (MN) test in the peripheral blood. It was observed that both acute and subchronic WAF exposure affected the investigated parameters in different ways. In general, the exposed groups presented higher mean values for the investigated parameters if compared with their respective controls. After the recovery experiment, the mean values of PAH metabolites, LPO, DNA damage and MN frequency were significantly lower than those of animals exposed for 168 h, indicating that the recovery period was appropriately long for the evaluated biomarkers return to the control levels. The results indicated that the selected H. reidi biomarkers proved to be adequate and complementary tools in determining the first impacts of acute and subchronic exposure caused by WAF of diesel fuel in fish, as well as their recovery in clean water.

Hoplosternum littorale is an Amazon fish that lives in urban areas surrounded by polluted igarapes, where elevated copper concentrations eventually occur. The central goal of this study was to evaluate the associated effects of high temperature and copper contamination on survival time and biochemical responses of the Amazonian fish species H. littorale. We exposed fish to two nominal dissolved copper concentrations (50 and 500 µg l−1) and combined temperatures of 28 and 34°C. Our findings showed that the combination of these variables affects the survival time of this species. The activity of the biotransformation enzymes ethoxyresorufin-O-deethylase and glutathione-S-transferase showed no alterations in fish within all treatments. The increase of reactive oxygen species and the decrease in potential total antioxidant capacity promoted the imbalance in the antioxidant system. An induction in superoxide dismutase activity occurred in fish exposed to copper concentrations of 50 and 500 µg l−1 at both temperatures, suggesting liver impairments. Thus, we suggest that H. littorale is sensitive to copper, and this sensitivity is increased further with exposure to high temperatures, particularly in the survival time and reactive oxygen species formation of this fish species.

Given the reported degraded nature of DOC in the Rio Negro, and low oxygen, pH, and bacterial riverine levels, we hypothesized: (1) DOC would have strong humic and fulvic acid fluorescence signals with high aromaticity and large mean molecular weight; and (2) photo-oxidation rates would be slow, and reactive oxygen species (ROS) concentrations low, producing no oxidative stress in biota. We surveyed the environment and properties of DOC and explored DOC photo-oxidation and fish sensitivity to DOC products. DOC properties were investigated using absorption and fluorescence indices and parallel factor analysis (PARAFAC) of excitation–emission matrices. ROS concentrations were measured spectrophotometrically. A native fish, Hemigrammus levis, was exposed to photo-oxidizing DOC and its tissues (brain, gill, liver) assayed for changes in antioxidant and biotransformation enzymes. With respect to our hypotheses, (1) DOC was highly terrigenous, with high SAC340 values (aromaticity), high capacity to produce ROS, and high tryptophan-like fluorescence (bacterial, autochthonous signal); (2) photo-oxidation rates were appreciable, while products were related to mean UV-radiation levels (total radiation was constant). ROS levels were often higher than freshwater averages, yet fish experienced no oxidative stress. Results suggest photo-oxidation influences patterns in C-cycling, bacterial production and community dynamics between wet and dry seasons.

The contamination of waterbodies is a worldwide concern due to the increasing urbanization and industrialization of the cities without good effluent management. Touristic cities can suffer with the number of people during high seasons periods, which can lead to an elevated use of natural resources and effluents discharges. Moreover, raining seasons, either high or low, can also play an important role in contaminating waterbodies once a dilution or concentration of contaminants may take place. The present study evaluated the water quality of the Tejereba River (Guarujá, Brazil) during the high season (January) and low season (March and May) in 2018. Reduction in water quality was observed in May, a month with low pluviosity and low tourism. The integrated data analysis (PCA) showed a positive correlation between the physicochemical parameters and the month of May, in which they were negatively correlated with pluviosity and the percentage of tourists. Despite the deterioration of water quality in May, no toxicity to Daphnia magna was observed. Our work showed that water quality (physicochemical and microbiological parameters), during the studied months, is more related to raining seasons than to the presence of tourists in Guarujá, Brazil. La contaminación de los cuerpos del agua es una preocupación mundial debido a la creciente urbanización y industrialización de las ciudades sin una buena gestión de los efluentes. Las ciudades turísticas pueden sufrir por la cantidad de personas mientras los períodos de temporada alta, lo que puede conducir a un alto uso de los recursos naturales y descarga de efluentes. Además, las temporadas de lluvias, sean altas o bajas, también pueden jugar un papel importante en la contaminación de los cuerpos del agua, ya que pueden producirse diluciones o concentraciones de contaminantes. El presente trabajo evaluó la calidad del agua del río Tejereba (Guarujá, Brasil) durante la temporada alta (enero) y temporada baja (marzo y mayo) en 2018. La reducción de la calidad del agua se observó en mayo, un mes de escasas precipitaciones y escaso turismo. El análisis integrado de datos (PCA) mostró una correlación positiva entre los parámetros físico-químicos y el mes de mayo, en el que se correlacionaron negativamente con las precipitaciones y el porcentaje de turistas. A pesar del deterioro de la calidad del agua en mayo, no se observó toxicidad para Daphnia magna. Nuestro trabajo mostró que la calidad del agua (parámetros físico-químicos y microbiológicos) en los meses evaluados está más relacionada con las temporadas de lluvias que con la presencia de turistas en la ciudad de Guarujá, Brasil. A contaminação de corpos d'água é uma preocupação mundial devido à crescente urbanização e industrialização das cidades sem um bom gerenciamento de efluentes. As cidades turísticas podem sofrer com o número de pessoas durante os períodos de alta temporada, o que pode levar a um elevado uso de recursos naturais e lançamento de efluentes. Além disso, as estações chuvosas, sejam altas ou baixas, também podem desempenhar um papel importante na contaminação de corpos d'água, uma vez que pode ocorrer diluição ou concentração de contaminantes. O presente trabalho avaliou a qualidade da água do rio Tejereba (Guarujá, Brasil) durante os períodos turísticos de alta (janeiro) e baixa temporada, (março e maio) no ano de 2018. A redução da qualidade da água foi observada em maio, mês de baixa pluviosidade e baixo turismo. A análise integrada de dados (PCA) mostrou correlação positiva entre os parâmetros físico-químicos e o mês de maio, na qual se correlacionaram negativamente com a pluviosidade e o percentual de turistas. Apesar da deterioração da qualidade da água em maio, nenhuma toxicidade para Daphnia magna foi observada. Nosso trabalho mostrou que a qualidade da água (parâmetros físico-químicos e microbiológicos), nos meses estudados, está mais relacionada às estações chuvosas do que à presença de turistas na cidade de Guarujá, Brasil.

Os impactos da visitação compreendem toda ação humana direta que provoque dano ao meio natural, relacionada ao comportamento inadequado do visitante ou aos problemas de planejamento para a demanda de uso. Portanto, o objetivo foi avaliar os possíveis impactos causados pela visitação de duas trilhas principais (Costão e Deserta), localizadas na Reserva de Desenvolvimento Sustentável da Barra do Una, durante o verão (alta visitação) e no outono (baixa visitação) de 2017. Para isso, as trilhas Costão e Deserta foram seccionadas, sendo respectivamente estabelecidos 4 e 10 pontos, onde foram avaliados indicadores de impactos físicos, biológicos e sociais por meio do método Visitor Impact Management. Os achados demonstraram, em ambas as trilhas, uma redução nos impactos relacionados aos problemas de drenagem, ao serem comparadas as estações do verão com o outono. A presença de lixo na trilha da Deserta na estação do outono foi menor quando comparada ao verão, enquanto os danos aos recursos naturais na trilha do Costão foram maiores no outono que no verão. Embora as trilhas estudadas estejam localizadas em uma Unidade de Conservação, a ausência de controle de visitação pública, assim como a falta de infraestrutura colaboram de forma negativa, resultando em danos de diferentes gravidades. Por fim, as ações propostas no presente estudo, como trilha guiada com monitor ambiental, controle de visitação pública, instalação de corrimãos, degraus e placas podem ser benéficas para reduzir e/ou reverter os impactos encontrados em ambas as trilhas.

The present study aimed to evaluate the biometric and hematological indices in Mugil curema collected in two Neotropical estuaries in the south coast of Brazil, and to investigate if such variables can be influenced by seasonality and degree of anthropogenic influence. Differences between seasons and estuarine systems were observed, where the dissolved oxygen and salinity, together with the historical contamination of the Santos estuarine system (SES), seem to play an important role in the biological response. Fish from the SES presented, in general, high responses of the hematological variables (red and white series) and the hepatosomatic index, relative to those fish from Peruibe estuarine system (PES), even with the remote contamination present at PES, while no erythrocytic abnormalities or micronucleus were observed in fish collected at SES and PES in both seasons. The present work demonstrated that M. curema collected at SES are experiencing hematological and metabolic perturbations that are not observed in fish collected at PES.

To assess how the quality and properties of the natural dissolved organic carbon (DOC) could drive different effects on gill physiology, we analysed the ionoregulatory responses of a native Amazonian fish species, the tambaqui Colossoma macropomum, to the presence of dissolved organic carbon (DOC; 10 mg l-1 ) at both pH 7.0 and pH 4.0 in ion-poor water. The DOC was isolated from black water from Sao Gabriel da Cachoeira (SGC) in the upper Rio Negro of the Amazon (Brazil) that earlier been shown to protect a non-native species, zebrafish Danio rerio against low pH under similar conditions. Transepithelial potential (TEP), net flux rates of Na+ , Cl- and ammonia and their concentrations in plasma and Na+ , K+ ATPase; v-type H+ ATPase and carbonic anhydrase activities in gills were measured. The presence of DOC had negligible effects at pH 7.0 apart from lowering the TEP, but it prevented the depolarization of TEP that occurred at pH 4.0 in the absence of DOC. However, contrary to our initial hypothesis, SGC DOC was not protective against the effects of low pH. Colossoma macropomum exposed to SGC DOC at pH 4.0 experienced greater net Na+ and Cl- losses, decreases of Na+ and Cl- concentrations in plasma and elevated plasma ammonia levels and excretion rates, relative to those exposed in the absence of DOC. Species-specific differences and changes in DOC properties during storage are discussed as possible factors influencing the effectiveness of SGC DOC in ameliorating the effects of the acid exposure.

We examined whether oxidative damage and antioxidant responses are more likely to occur during hypoxia or re-oxygenation in hypoxia-tolerant fish, and whether there is an influence of the rate of re-oxygenation. An hypoxia/re-oxygenation experiment using wild-caught Cyphocharax abramoides (Rio Negro, Brazil), was designed to answer these questions. Lipid peroxidation (MDA), a measure of oxidative damage, and antioxidant activities (superoxide dismutase (SOD), glutathione peroxidase (GPx), antioxidant capacity against peroxyl radicals (ACAP)), were measured in brain, gill and liver tissues after normoxia, 3-h hypoxia (2.7 kPa), and 3-h hypoxia followed by 1-h or 3-h re-oxygenation, implemented either immediately or slowly (3.0 kPa·h −1 ). Critical oxygen tension of routine oxygen consumption rate (Pcrit) (4.1 kPa) and the P O2 at loss of equilibrium (LOE) (1.7 kPa) were determined to set the experimental hypoxia exposure. The Regulation Index, a measure of oxyregulation with declining P O2 , was 0.32. Oxidative damage occurred during hypoxia: no additional damage was observed during re-oxygenation. Tissues responded differentially. GPx and MDA rose in the brain and gills, and SOD (and likely GPx) in the liver during hypoxia. Antioxidants increased further at LOE. Rate of oxygen increase during re-oxygenation did not affect antioxidant responses. In brain and gills, GPx and MDA decreased or recovered after 1-h re-oxygenation. In liver, SOD remained high and GPx increased. In summary, C. abramoides incurred oxidative damage during hypoxic exposure with no additional damage inflicted during re-oxygenation: the rate of re-oxygenation was inconsequential. Literature data support conclusion of greater damage during hypoxia than during re-oxygenation in hypoxia-tolerant fish.

Many cities worldwide are established adjacent to estuaries and their catchments resulting in estuarine contamination due to intense anthropogenic activities. The aim of this study was to evaluate if fish living in an estuarine urban waterway were affected by contamination, via the measurement of a suite of biomarkers of fish health. Black bream (Acanthopagrus butcheri) were sampled in a small urban embayment and a suite of biomarkers of fish health measured. These were condition factor (CF), liver somatic index (LSI), gonadosomatic index (GSI), hepatic EROD activity, polycyclic aromatic hydrocarbon (PAH) biliary metabolites, serum sorbitol dehydrogenase (s-SDH) and branchial enzymes cytochrome C oxidase (CCO), and lactate dehydrogenase (LDH) activities. The biomarkers of exposure EROD activity, and pyrene- and B(a)P-type biliary metabolites confirmed current or recent exposure of the fish and that fish were metabolizing contaminants. Relative to a reference site, LSI was higher in fish collected in the urban inlet as was the metabolic enzyme LDH activity. CF, GSI, s-SDH, CCO, and naphthalene-type metabolites were at similar levels in the urban inlet relative to the reference site. PAH biliary metabolite ratios of high-molecular-weight to low-molecular-weight suggest that fish from the urban inlet were exposed to pyrogenic PAHs, likely from legacy contamination and road runoff entering the embayment. Similarly, the sediment PAH ratios and the freshness indices suggested legacy contamination of a pyrogenic source, likely originating from the adjacent historic gasworks site and a degree of contamination of petrogenic nature entering the inlet via storm water discharge. Biomarkers of exposure and effect confirmed that black bream collected in the Claisebrook Cove inlet, Western Australia, are currently exposed to contamination and are experiencing metabolic perturbations not observed in fish collected at a nearby reference site.

Increasing and constant pollution is causing continuous environmental damage in marine and freshwater aquatic environments. Both environments are constantly subject to pollution caused by polycyclic aromatic hydrocarbons (PAHs). To study all levels of responses provoked by contaminants, we propose that fish are excellent models. The tambaqui is an important freshwater fish endemic from the Orinoco and Amazon River Basins. In the presence of PAHs and other crude oil components, this fish accumulates PAH metabolites in the bile and presents genotoxic effects in its red blood cells. These responses are dose-dependent. Tambaqui also present changes in biotransformation and antioxidant enzymes, which are considered great bioindicators for the evaluation of PAH contamination. In the marine environment, the seahorses are usually found in estuarine and coastal environments, such as reefs, bays, seaweed banks and seagrass. Genotoxic effects are also observed in seahorse exposed to PAHs, with a significant relationship between DNA damage and increased crude oil concentration. Regarding biochemical responses, the seahorse presents decreased levels of GST in a dose-dependent manner. This fish also presents gill histopathological alterations and the damages observed were classified as defense or compensatory responses. Both tambaqui and seahorse are considered excellent bioindicators for PAH contamination since they are extremely responsive to these organic strong pollutants.

This study evaluates the contaminants in water and their bioaccumulation in the gills and liver of two ecologically distinct fish species, Astyanax fasciatus and Pimelodus maculatus, living in the reservoir of the Furnas hydroelectric power station located in Minas Gerais in the southeastern Brazil. The histological alterations in these organs are also examined. Water and fish were collected in June and December from five sites (site 1: FU10, site 2: FU20, site 3: FU30, site 4: FU40 and site 5: FU50) in the reservoir, and agrochemicals and metals selected based on their use in the field crops surrounding the reservoir were analyzed in the water and in the fish gills and livers. The concentrations of the organochlorines aldrin/dieldrin, endosulfan and heptachlor/heptachlor epoxide as well as the metals copper, chromium, iron and zinc in the gills and livers of both fish species were higher in June than in December; the liver accumulated higher concentrations of contaminants than the gills. The organochlorine metolachlor was detected only in the liver. The histological pattern of changes was similar in both species with regard to contaminant accumulation in the gills and liver. Fish from FU10, the least contaminated site, exhibited normal gill structure and moderate to heavy liver damage. Fish collected at FU20 to FU50, which were contaminated with organochlorines and metals, showed slight to moderate gill damage in June and irreparable liver damage in the livers in June and December. The histological changes in the gills and liver were suitable to distinguishing contaminated field sites and are therefore useful biomarkers for environmental contamination representing a biological end-point of exposure.

This study investigated the relationship between contaminant body burden and the oxidative stress status of the gills and livers of two wild fish species in the Furnas Hydroelectric Power Station (HPS) reservoir (Minas Gerais, Brazil). Gills and livers presented similar pathways of metals and organochlorine bioaccumulation. During June, organochlorines were associated with lipid peroxidation (LPO), indicating oxidative stress due to the inhibition of the antioxidant enzymes superoxide dismutase and glutathione peroxidase. In the most polluted areas, metal concentrations in the liver were associated with metallothionein. During December, contaminants in the gills and liver were associated with catalase activity and LPO. Aldrin/dieldrin was the contaminant most associated with oxidative damage in the livers of both species. This integrated approach shed light on the relationship between adverse biological effects and bioaccumulation of contaminants inputted by intensive agricultural practices and proved to be a suitable tool for assessing the environmental quality of man-made reservoirs.

The condition factor and blood variables, including erythrocyte lipid peroxidation (LPO) and the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), in two ecologically distinct fish species (Astyanax fasciatus and Pimelodus maculatus) were evaluated at five sites in the Furnas Hydroelectric Power Station reservoir (Brazil) to assess water quality. Aldrin/dieldrin, endosulfan, heptachlor epoxide, and metolachlor were detected at different concentrations in four of the sites. Condition factor was not directly affected by such contaminants. A negative correlation between hematocrit and heptachlor was detected in P. maculatus. Positive correlations between red blood cells and heptachlor as well as an interactive effect of metolachlor and aldrin/dieldrin were detected in A. fasciatus. The erythrocytes of both species collected from the contaminated sites showed high levels of LPO, an increase in SOD and GPx activities and a decrease in CAT activity. Although the leukocyte number and the differential percentage of leukocytes varied among the sites, the hematological variables, the LPO levels, and the antioxidant enzyme activities could be used to assess water quality, regardless of the differences in the responses of the fish species.

Through integrating chemical, biochemical and morphological analyses, this study investigated the effects of multiple pollutants on the gill mitochondria-rich cells (MRCs) in two fish species, Astyanax fasciatus and Pimelodus maculatus, collected from five sites (FU10, FU20, FU30, FU40 and FU50) in the Furnas Hydroelectric Power Station reservoir. Water analyses revealed aluminum, iron and zinc as well as organochlorine (aldrin/dieldrin, endosulfan, heptachlor/heptachlor epoxide and metolachlor) contamination at all of the sites, with the exception of FU10. Copper, chrome, iron and zinc were detected in the gills of both species, and aldrin/dieldrin, endosulfan and heptachlor/heptachlor epoxide were detected in the gills of fish from all of the sites, with the exception of FU10. Fish collected at FU20, FU30 and FU50 exhibited numerous alterations in the surface architecture of their pavement cells and MRCs. The surface MRC density and MRC fractional area were lower in fish from FU20, FU30, FU40 and FU50 than in those from the reference site (FU10) in the winter, and some variability between the sites was observed in the summer. The organochlorine contamination at FU20 and FU50 was associated with variable changes in the MRCs and inhibition of Na(+)/K(+)-ATPase (NKA) activity, especially in P. maculatus. At FU30, the alterations in the MRCs were associated with the contaminants present, especially metals. A multivariate analysis demonstrated a positive association between the biological responses of both species and environmental contamination, indicating that under realistic conditions, a mixture of organochlorines and metals affected the MRCs by inhibiting NKA activity and inducing morphological changes, which may cause an ionic imbalance.