Effect of a heavy metal model mixture on biological parameters of rainbow trout <Emphasis Type="Italic">oncorhynchus mykiss</Emphasis>

The effects of a model mixture (HMMM) of seven heavy metals (Cu, Zn, Ni, Cr, Pb, Cd, Mn) on the rainbow trout Oncorhynchus mykiss at all stages of development (embryos, larvae, adults) were investigated based on the annual average concentrations of these metals in cooling waste waters discharging from Ignalina Nuclear Power Plant (Lithuania) into the Drūk?iai lake. According to mortality parameters, the most sensitive to HMMM were larvae, although no significant differences between the sensitivity of embryos and adult fish to HMMM were found. Maximal toxic effect of HMMM was observed during the hatching period. Long-term exposure to sublethal concentrations of HMMM affected embryo development, growth of larvae, their cardio-respiratory and behavioural responses, induced significant changes in morphological, morpho-physiological, physiological and haematological parameters of adult fish. Respiratory responses and growth parameters of fish were found to be the most sensitive to low concentrations of HMMM. Adult fish were capable of detecting and avoiding low, sublethal concentrations of HMMM. Heavy metals in a mixture at low concentrations were more toxic than single ones. According to the background of the damages induced by HMMM, after-effects in a fish organism, as well as in a whole population, can be predicted.     

Acute and Chronic Toxicity of Chlorine Dioxide (ClO2) and Chlorite (ClO2ˉ) to Rainbow Trout (Oncorhynchus mykiss) (4 pp)

Goal, Scope and Background Chlorite (ClO2ˉ) is a primary decomposition product when chlorine dioxide (ClO2) is added during water treatment; therefore the toxic effects of both compounds on aquatic organisms are possible. Limited data are available concerning their toxicity to fish. The aim of this study was to investigate sensitivity of rainbow trout to acute and chronic toxicity of chlorine dioxide and chlorite, and to estimate the Maximum-Acceptable-Toxicant-Concentration (MATC) of those compounds in fish. Methods The acute and chronic toxicity of chlorine dioxide and chlorite to larval and adult rainbow trout was investigated in 96-hour to 20-day laboratory exposures evaluating the wide range spectrum of biological indices under semi-static conditions. Results and Discussion Median lethal concentration (96-hour LC50) values derived from the tests were: 2.2 mg/l for larvae; 8.3 mg/l for adult fish and 20-day LC50 for larvae was 1.6 mg/l of chlorine dioxide, respectively. Chlorite was found to be from 48 to 18 times less acutely toxic to larvae and adult fish, correspondingly. Both chemical compounds induced similar toxic effects in rainbow trout larvae during chronic tests (they affected cardio-respiratory and growth parameters), but chlorine dioxide had a higher toxic potency than chlorite. A significant decrease in the heart rate and respiration frequency of larvae was established. However, within an increase in exposure duration recovery of cardio-respiratory responses was seen to have occurred in larvae exposed to chlorite. Meanwhile, in larvae exposed to chlorine dioxide, a significant decrease in cardio-respiratory responses remained during all 20-day chronic bioassays. Chlorine dioxide also more strongly affected growth parameters of rainbow trout larvae at much lower test concentrations. Decreased rate of yolk-sack resorption occurred only in the tests with chlorine dioxide. Conclusions Maximum-Acceptable-Toxicant-Concentration (MATC) of 0.21 mg/l for chlorine dioxide and of 3.3 mg/l for chlorite to fish was derived from chronic tests based on the most sensitive parameter of rainbow trout larvae (growth rate). According to substance toxicity classification accepted for Lithuanian inland waters, chlorine dioxide and chlorite can be referred to substances of \moderate\ toxicity to fish. Recommendations and Outlook Due to its very reactive nature, chlorine dioxide is rapidly (in a few hours) reduced to chlorite, which is persistent also as a biocide but 16 times less toxic to fish, according to MATC. Therefore, it is much more likely that fish will be exposed to chlorite than to chlorine dioxide in natural waters. Presently accepted, the Maximum-Permitted-Concentration of total residual chlorine (TRC) in waste-water discharging into receiving waters is 0.6 mg/l. If this requirement will not be exceeded, it is unlikely that fish would be exposed to lethal or even to sublethal concentrations of chlorine dioxide or chlorite. Furthermore, chlorine dioxide does not generate toxic nitrogenous (chloramines) or carcinogenic organic residuals (trihalomethanes). All these properties make chlorine dioxide a more promising biocide than chlorine.     

Assessment of the phototoxicity of weathered Alaska North Slope crude oil to juvenile pink salmon

Petroleum products are known to have greater toxicity to the translucent embryos and larvae of aquatic organisms in the presence of ultraviolet radiation (UV) compared to toxicity determined in tests performed under standard laboratory lighting with minimal UV. This study assessed the acute phototoxicity of the water accommodated fractions of weathered Alaska North Slope crude oil (ANS) to juvenile pink salmon, which are a heavily pigmented life stage. Fish in the highest ANS treatments exhibited melanosis, less mobility, reduced startle response, erratic swimming, and loss of equilibrium. Gills from fish exposed to ANS had elevated levels of hydroperoxides in oil-only, UV-only, and oil+UV treatments compared to control fish, which was indicative of increased lipid peroxidation in gill tissue. Under the test conditions of moderate salinity, low UV and high short-term oil exposure there were no indications of photoenhanced toxicity as assessed by elevation of mortality, behavioral impairment, or gill lipid peroxidation in oil+UV treatments. The results of this study suggest that pink salmon may be at less risk from photoenhanced toxicity compared to the translucent early-life stages of several other Alaska species.     

Toxic effects of orimulsion on rainbow trout <Emphasis Type="Italic">oncorhynchus mykiss</Emphasis>

GOAL, SCOPE AND BACKGROUND: Orimulsion (stable emulsion of natural bitumen and water) is a new imported industrial fuel in Lithuania. No data on its toxicity to fish is freely available. The aim of this study was to investigate sensitivity of rainbow trout (Oncorhynchus mykiss) to acute and chronic toxicity of orimulsion and to estimate the Maximum Acceptable Toxicant Concentration (MATC) of orimulsion to fish. METHODS: Laboratory tests were conducted on rainbow trout in all stages of development (embryos, larvae, adults). Acute toxicity (96-hour duration) and long-term (28 or 60-day duration) tests evaluating the wide range spectrum of biological indices were performed under semi-static conditions. RESULTS AND DISCUSSION: Median lethal concentration (96-hour LC50) values and their 95% confidence intervals derived from the tests were: 0.1 (0.09-0.12) to embryos, 0.06 (0.05-0.07) to larvae and 2.22 (2.02-2.43) to adult fish, and 28-day LC50 to adult fish was found to be 0.26 (0.21-0.32) g/l of total orimulsion respectively. The acute toxicity of orimulsion to rainbow trout can be characterised by a narrow zone of toxic effect and a sharp boundary between lethal and sublethal concentrations. The lowest 'safe' or 'no-effect' concentration values of total orimulsion obtained in long-term tests were equal to 0.09 g/l to adult fish, 0.019 g/l to embryos, and 0.0017 g/l to larvae. Proposed value of 'application factor' for orimulsion was found to be equal to 0.03. Since orimulsion has the property to disperse in all water volume, its toxic effect on fish can be characterised by the combined effects of dispersion and water-soluble-fraction. CONCLUSIONS: Maximum Acceptable Toxicant Concentration (MATC) of 0.0017 g/l of total orimulsion to fish was derived from long-term tests based on the most sensitive parameter of rainbow trout larvae (relative mass increase at the end of the test). According to substance toxicity classification accepted for Lithuanian inland waters, orimulsion can be referred to substances of 'moderate' toxicity to fish. RECOMMENDATIONS AND OUTLOOK: For prediction and evaluation of toxic impact of orimulsion accident spills on fish, some recommendations should be given. Since orimulsion has the property to disperse in all water volume during short time periods, the amounts of both spilled orimulsion and polluted water should be ascertained. Once both parameters are known, the real concentration of orimulsion in the water body must be determined. Then this concentration must be compared with 'safe' concentration to fish. By use of 'application factor' 0.03, approximate MATC for other fish species can be estimated when only acute toxicity data (96-hour LC50 value) is available.     

Evidence for bioamplification of nine polychlorinated biphenyl (PCB) congeners in yellow perch (Perca flavascens) eggs during incubation

This study investigated bioamplification of polychlorinated biphenyls (PCBs) in yellow perch (Perca flavescens) eggs resulting from nutrient utilization by developing embryos during incubation. Newly fertilized eggs containing trace levels of PCBs via maternal deposition were collected from an aquaculture pond in which adult broodstock had been reared over their natural lives. The eggs were incubated using a flow through system that received the same pond water at in-situ temperatures from which they were spawned. Replicate samples of eggs were collected at six time points throughout incubation, ranging from day 0 (newly fertilized eggs) to post-hatch larvae (2-d old). Congener specific PCB fugacities in pooled egg samples showed increases over the incubation period. Just prior to hatching, incubated eggs averaged 2.7-fold higher PCB fugacities compared to fresh eggs. The increase in PCB fugacity with egg incubation time was independent of chemical K_OW. After hatching, PCB residues were lost from the larvae, attenuating the maximum chemical fugacity achieved in late-incubated eggs. However, the rate of PCB elimination in the early larvae stages was K_OW dependent such that a significant larvae/egg fugacity ratio was still evident for intermediate and highly hydrophobic compounds 2 d post-hatching. This study provides the first evidence of in-ovo PCB bioamplification in eggs of an aquatic species and suggests that incubating fish embryos are exposed to higher chemical fugacities in-ovo than would be predicted by maternal deposition alone.     

Toxicity of acid-sulphate soil leachate and aluminium to the embryos and larvae of Australian bass (Macquaria novemaculeata) in estuarine water

The toxicity of leachate water from acid-sulphate soil to the early life stages of Australian bass, Macquaria novemaculeata, incubated in seawater was evaluated. Acid-sulphate soil leachate water (pH> or =6.8) delayed the hatching of fertilised eggs, but after 48 h the per cent hatching was normal. In comparison, acidic saline water (25 per thousand salinity) at pH 4.0 or less prevented embryos from hatching. The survival of yolk-sac larvae exposed to acid-sulphate soil leachate water at a concentration of 32% in seawater and an initial pH of 7.2, was significantly different to controls after 96 hours. In corresponding tests with only acidified saline water (20 per thousand salinity), pH levels equal to or below 5.0 killed yolk-sac larvae after 96 h exposure. Aluminum showed a pH dependent toxicity to yolk-sac larvae, with added aluminium as low as 200 microg litre(-1) having a significant effect on larval survival at pH 5.5, and concentrations of 600-800 microg litre(-1) having a significant effect on larval survival at an initial pH range of 6.0 < pH < 6.8. It was concluded that significant mortality of the early life stages of Australian bass would occur if they are exposed to acid-sulphate soil leachate that results in a pH in the receiving estuarine water below 5.5, or when the pH is below 6.8 and aluminium is present at a total concentration of 800 microg litre(-1) or greater.     

Characteristics of Oil Field Emissions in the Vicinity of Tulsa,Oklahoma

In 1988 a study was undertaken in the vicinity of Tulsa, Oklahoma to determine the characteristics, composition, and relative concentrations of the oil field emissions of volatile organic compounds (VOC). Forty grab samples (10-minute) using stainless steel canisters were collected from five different stages of crude oil production over an 80-day period (August-October). The samples were analyzed at the Tulsa City-County Health Department’s laboratory, using cryogenic preconcentration, gas chromatographic separation, and flame ionization detection. The six prevalent components of the oil field emissions were ethane, propane, 2- methyl propane, n-butane, 2-methylbutane, and n-pentane with propane predominating. The composition is unique with higher amounts of propane than ethane and is different from natural gas which has more abundant ethane. Decreases occurred in the amounts of light compounds, namely, ethane and propane from well heads through refinery tanks. The bulk of these losses appeared to be at the well heads and gathering tanks.     

秸秆固定化石油降解菌降解原油的初步研究

用秸秆做载体固定嗜碱芽孢杆菌(Bacillus alcalophilus SG)降解原油,其原油去除率为73.88%,高于单纯投加菌液或者菌液与秸秆的混合物的原油去除率.秸秆的最佳投加量(干重)为25.0 g/L,最佳固定化时间为30 h.用预处理过的秸秆固定SG,降低了固定化SG的原油去除率.在固定化培养基中添加无机盐离子,促进了固定化SG对原油的降解.不同初始pH的原油培养基在固定化SG降解原油的过程中逐渐呈中性或偏碱性.固定化SG在pH 6.0～10.0时对原油均有不错的降粘能力.     

Acute toxicity of the insect larvicide abate® (temephos) on the fish tilapia melanopleura and the dragonfly larvae neurocordelia virginiensis.

Abstract

Acute bioassay tests on the toxic effects of the insect larvicide Abate® (temephos) on the mouth brooder cichlid fish Tilapia melanopleum and the dragonfly larvae (Odonata) Neurocordulia virginiensis were conducted in static non renewal toxicity test set ups. The 96h‐LC50 (95% confidence intervals) was 30.2 (20.5‐ 44.20) mg/L for the fish and 2.0 (1.16–2.0) mg/L for the dragonfly larvae. The dragonfly larvae were 15 times more susceptible to the larvicide than the tilapia. The calculated NOEC (No Observable Effect Concentration) was 14.1 mg/L for the fishand less than 1.0 mg/L for the insect larvae. The estimated ‘safe’ concentration of the pesticide to the fish was 3.0 mg/L and 0.2 mg/L for insect larvae. These figures are far above the concentrations approved for use in the control of mosquito larvae(0.0004–0.01 mg/L). It appears that the application of toxic levels of the insecticide for the elimination of some aquatic invertebrates may be ‘safe’ for normal survival, growth and reproduction offish and some aquatic insect larvae.     

A multiple testing approach for hazard evaluation of complex mixtures in the aquatic environment: the use of diesel oil as a model

Traditional single species toxicity tests and multiple component laboratory-scaled microcosm assays were combined to assess the toxicological hazard of diesel oil, a model complex mixture, to a model aquatic environment. The immediate impact of diesel oil dosed on a freshwater community was studied in a model pond microcosm over 14 days: a 7-day dosage and a 7-day recovery period. A multicomponent laboratory microcosm was designed to monitor the biological effects of diesel oil (1.0 mg litre(-1)) on four components: water, sediment (soil + microbiota), plants (aquatic macrophytes and algae), and animals (zooplanktonic and zoobenthic invertebrates). To determine the sensitivity of each part of the community to diesel oil contamination and how this model community recovered when the oil dissipated, limnological, toxicological, and microbiological variables were considered. Our model revealed these significant occurrences during the spill period: first, a community production and respiration perturbation, characterized in the water column by a decrease in dissolved oxygen and redox potential and a concomitant increase in alkalinity and conductivity; second, marked changes in microbiota of sediments that included bacterial heterotrophic dominance and a high heterotrophic index (0.6), increased bacterial productivity, and the marked increases in numbers of saprophytic bacteria (10 x) and bacterial oil degraders (1000 x); and third, column water acutely toxic (100% mortality) to two model taxa: Selenastrum capricornutum and Daphnia magna. Following the simulated clean-up procedure to remove the oil slick, the recovery period of this freshwater microcosm was characterized by a return to control values. This experimental design emphasized monitoring toxicological responses in aquatic microcosm; hence, we proposed the term 'toxicosm' to describe this approach to aquatic toxicological hazard evaluation. The toxicosm as a valuable toxicological tool for screening aquatic contaminants was demonstrated using diesel oil as a model complex mixture.     

中原油田石油污染土壤原位生物修复技术实验研究

通过实验室选择性富集培养,从中原油田石油污染土壤中获得了能以中原原油为碳源快速生长的石油降解菌群。结合黑麦草（Ryegrass）和苜蓿（Alfalfa）,采用该降解菌群对原油污染土壤进行了原位生物联合修复实验。接入降解菌的实验区分种植黑麦草、种植苜蓿、未种植区,另设黑麦草区和空白区。经过99 d的生物修复,石油烃累计降...     

Field investigation on the toxicity of Alaska North Slope crude oil (ANSC) and dispersed ANSC crude to Gulf killifish, Eastern oyster and white shrimp

A field investigation was conducted on a Louisiana Spartina alterniflora shoreline to evaluate the toxic effects of crude oil (Alaska North Slope crude oil, ANSC) and dispersed oil (ANSC + dispersant Corexit 9,500) on three aquatic species indigenous to the Gulf of Mexico: Fundulus grandis (Gulf killifish), Crassostrea virginica (Eastern oyster), and Litopenaeus setiferus (white shrimp). Results indicated that total hydrocarbons concentration value in oiled treatments decreased rapidly in 3h and were below 1 ppm at 24h after initial treatment. Corexit 9,500 facilitated more ANSC fractions to dissolve and disperse into the water column. L. setiferus showed short-term sensitivity to the ANSC and ANSC + 9,500 at 30 ppm. However, most test organisms (>83%) of each species survived well after 24h exposure to the treatments. Laboratory tests conducted concurrent with the field investigation indicated that concentrations of crude oil higher than 30 ppm were required for any significant toxic effect on the juvenile organisms tested.     

Responses of juvenile sea bass, Dicentrarchus labrax, exposed to acute concentrations of crude oil, as assessed by molecular and physiological biomarkers

In the present study, juvenile sea bass were exposed for 48 and 96 h to an Arabian light crude oil and their responses were assessed at the molecular and physiological levels. The aim of the study was therefore to assess (i) the short term effects of crude oil exposure by the measurement of several molecular biomarkers, (ii) the consequences of this short term exposure on fish health by using growth and condition indices measured after a decontamination period of 28 and 26 d in seawater. Hydrocarbon petroleum concentrations was monitored during the 96 h experiments and an increase of PAH concentrations were found in fish following both exposure times. An 7-ethoxyresorufin-O-deethylase (EROD) induction was observed after 48 h of exposure, while a significant decrease in the sea bass specific growth rate in length and for the RNA:DNA ratio was observed 28 d after that exposure ceased. The EROD induction doubled after the 96 h exposure, and a significant increase in GST activities was observed. A significant decrease in the specific growth rates, the otolith recent growth, the RNA:DNA ratio and the Fulton’s K condition index were then observed in sea bass 26 d after the 96 h exposure to mechanically dispersed crude oil compared to the control. The present study shows that growth and condition indices can prove useful in assessing fish health status following an oil spill. Their complementary analysis with sensitive molecular biomarkers as EROD could improve the determination of oil spill impact on fish populations.     

Monitoring contaminants from oil production at sea by measuring gill EROD activity in Atlantic cod (Gadus morhua)

An ex vivo gill EROD assay was applied in Atlantic cod (Gadus morhua) as a biomarker for waterborne CYP1A-inducing compounds derived from oil production at sea. Exposure to nominal concentrations of 1 ppm or 10 ppm North Sea crude oil in a static water system for 24 h caused a concentration-dependent gill EROD induction. Further, exposure of cod for 14 days to environmentally relevant concentrations of produced water (PW, diluted 1:200 or 1:1000) from a platform in the North Sea using a flow-through system resulted in a concentration-dependent induction of gill EROD. Crude oil (0.2 ppm) from the same oil field also proved to induce EROD. Finally, gill EROD activity in cod caged for 6 weeks at 500-10 000 m from two platforms outside Norway was measured. The activities in these fish were very low and did not differ from those in fish caged at reference sites.     

The impact of sewage sludge exposure on the reproduction of the sand goby, Pomatoschistus minutus

Adult sand gobies were exposed to 0.1% sewage sludge for 19 weeks prior to the end of spawning. Exposure to sewage sludge had a significant effect on male mortality rates but no significant effects on the gonadosomatic index of males or females. There were no major effects of sludge exposure on testes androgen content or on testes release of androgens after in vitro gonadotrophin stimulation. Fecundity and the number of larvae produced were not significantly affected by the sludge exposure. There was a tendency for eggs and larvae from sludge-exposed females to have a higher mortality rate. At a population level, however, there was a major reduction in the number of eggs and larvae produced in the sludge-exposed population which reflected a failure of some females to spawn. Of the larvae produced, 60-70% from sludge-exposed parents were lighter and had a larger yolk-sac volume compared to larvae from non-exposed parents which may have indicated impaired yolk utilisation.     

Brazilian Oil Spills Chemical Characterization--Case Studies

In the last decade, PETROBRAS has experienced some significant oil spills cases and the PETROBRAS Research Center has played an important role in the company emergency response program by characterizing the spilled oil, monitoring the affected ecosystem, determining the fate of the oil in the environment, and, subsequently, helping the company in assessing the environmental damage. This paper presents the use of advanced chemical analytical techniques (GC/FID, P&T/GC/PID and GC/MS) in some Brazilian oil spill studies in order to determine fractions and individual petroleum hydrocarbons in different matrices such as water, groundwater, sediment, sand, fish and the spilled oil itself. The spill studies encompassed crude and fuel oil releases on land and coastal ecosystems, related to the incidents in Guanabara Bay (Rio de Janeiro), Barigui and Iguassu Rivers (Parana) and Sao Sebastiao Channel (Sao Paulo). Total petroleum hydrocarbons (TPH), n -alkanes, isoprenoids, unresolved complex mixtures (UCM), volatile monoaromatic compounds--benzene, toluene, ethylbenzene and xylenes (BTEX), parent and alkylated homologues polycyclic aromatic hydrocarbons (PAH), and terpanes and steranes were characterized for determining correlation to the spilled oil and other known oil sources and environmental assessment. Some of the acute ecotoxicity data for water and sediment samples is also presented.     

Anti-oxidative property of crude rice oil extracted from cadmium-contaminated rice

Local residents who habitually consume cadmium-contaminated rice (Oryza sativa L.) can be exposed to cadmium toxicity in Mae Sot District, Tak Province, Thailand. This study aimed to investigate an alternative for utilizing cadmium-contaminated rice without compromising their health with hazard risks. First, cadmium (Cd) concentration in rice grain and crude rice oil was determined (0.203 ± 0.030 and 0.007 ± 0.002 mgCd/kg dry weight, respectively). Then crude rice oil extracted from cadmium-contaminated rice grain was studied for its anti-oxidative property using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging approach. Next, quantitative analysis of γ-oryzanol in crude rice oil was conducted. Results indicated that the level of cadmium concentration in the rice grain could cause adverse effects on human health. However, the amount of cadmium in the crude rice oil was safe for consumption. In crude rice oil anti-oxidative property, crude rice oil extracted from cadmium-contaminated rice was significantly higher than the control (P < 0.05). The concentration of γ-oryzanol in crude rice oil extracted from cadmium-contaminated rice was significantly higher than that in the control crude rice oil (P < 0.05). This study demonstrates an alternative way to use the rice grown in cadmium-contaminated areas for crude rice oil production for its anti-oxidative properties.     

Bioconcentration of trans-chlordane by the midge, Chironomus decorus

The accumulation and transport of the organochlorine pesticide, trans-chlordane, by the midge, Chironomus decorus was examined in a whole life cycle laboratory exposure assay. Larvae were kept in dosed water exposures including food particles from egg stages through adult metamorphosis and were sampled for weight gain and chemical content over the course of the 50 day study. Accumulation of trans-chlordane was related to the amount of contaminant in the larval environment. Concentration of trans-chlordane (ng contaminant/g tissue) in larvae was not significantly different from second through fourth instar stages but depended upon the weight of the larvae. Differences in time to metamorphosis, weight gain and sex ratios occurred among all replicate exposures, including controls, suggesting nongenetic maternal differences, rather than environmental variation caused by chemical exposure. When the larvae metamorphosed, an average of 82.6% of the contaminant was retained in the adults while 11.4% was left behind in the shed exuviae. This study suggests that terrestrial predators feeding on emerging aquatic insects can be exposed to organic pesticides from aquatic environments.     

Biochemical responses in armored catfish (Pterygoplichthys anisitsi) after short-term exposure to diesel oil,pure biodiesel and biodiesel blends

Biodiesel fuel is gradually replacing petroleum-based diesel oil use. Despite the biodiesel being considered friendlier to the environment, little is known about its effects in aquatic organisms. In this work we evaluated whether biodiesel exposure can affect oxidative stress parameters and biotransformation enzymes in armored catfish (Pterygoplichthys anisitsi, Loricariidae), a South American endemic species. Thus, fish were exposed for 2 and 7 d to 0.01 mL L⁻¹ and 0.1 mL L⁻¹ of pure diesel, pure biodiesel (B100) and blends of diesel with 5% (B5) and 20% (B20) biodiesel. Lipid peroxidation (malondialdehyde) levels and the activities of the enzymes glutathione S-transferase, superoxide dismutase, catalase and glutathione peroxidase were measured in liver and gills. Also, DNA damage (8-oxo-7, 8-dihydro-2′-deoxyguanosine) levels in gills and 7-ethoxyresorufin-O-deethylase activity in liver were assessed. Pure diesel, B5 and B20 blends changed most of the enzymes tested and in some cases, B5 and B20 induced a higher enzyme activity than pure diesel. Antioxidant system activation in P. anisitsi was effective to counteract reactive oxygen species effects, since DNA damage and lipid peroxidation levels were maintained at basal levels after all treatments. However, fish gills exposed to B20 and B100 presented increased lipid peroxidation. Despite biodiesel being more biodegradable fuel that emits less greenhouse gases, the increased lipid peroxidation showed that biofuel and its blends also represent hazards to aquatic biota.