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Anthranilic diamides (AD) are a modern class of insecticides used as alternatives to pyrethroids and neonicotinoids, particularly against lepidopteran pests. Despite their widespread use and presence in surface waters, little is known regarding their effects on amphibians. The aim of this study was to examine the effects of environmentally-relevant concentrations of AD insecticides chlorantraniliprole (CHLO) and cyantraniliprole (CYAN) on metamorphosis of the toad Rhinella arenarum . Tadpoles were exposed to CHLO or CYAN at concentrations ranging from 5 and 5000 µg/L from stage 27 until metamorphosis completion. Both insecticides produced a non-monotonic acceleration of the time required for individuals to progress through development and a decrease in the proportion of individuals completing metamorphosis, although a delay in metamorphosis was also observed at 5 µg/L of CHLO. Snout-vent length and body weight of metamorphosed toads were not markedly affected by either insecticide. CHLO was more toxic than CYAN, with a lowest observed effect concentration (LOEC) for CHLO on time to metamorphosis defined as 5 µg/L compared to 5000 µg/L for CYAN. The LOEC for reduced metamorphic success defined as 50 µg/L for CHLO compared to 500 µg/L for CYAN. As most effects occurred after stage 39, when metamorphosis depends upon thyroid hormones, it is conceivable that that AD insecticides act as endocrine disruptors. These findings suggest that contamination of surface waters with CHLO and CYAN may disrupt amphibian development in the wild and warrant further research to investigate the possibility of endocrine-disruption by ADs.

The wide use of neonicotinoid seed treatment represents a hazard for farmland birds that feed on treated seeds. This study aimed to characterize the long-term effects of the neonicotinoid imidacloprid (IMI) in the passerine grayish baywing (Agelaioides badius). The birds were fed ad libitum for 32 days only with seeds treated with 53.1 (Low, 11 % of LD50) and 514 (High, (112 % of LD50) mg IMI/kg seed; these concentrations representing respectively, 1.8 and 17.1 % of 3 g IMI/kg, an average application rate used to treat crop seeds in Argentina. The effects exerted by IMI on birds were evaluated at behavioral, physiological, hematological, genotoxic, and biochemical levels. No differences in food consumption were observed between Control and Low treatments birds, indicating a lack of aversion to treated seeds. High treatment birds only decreased their food consumption by 20 % in the first 3 days of exposure. Birds from High treatment experienced an early loss of body weight, reduction in their mobility, lack of response to threats (i.e., predator call and approaching person), and altered their use of the cage. On the contrary, birds from Low treatment experienced a delay in the onset of effects like reduction in mobility, lack of response to threats, and a tendency to reduce their body weight. At the end of exposure, glutathione S transferase activity in the plasma of treated birds decreased, and cholinesterase activity increased in the liver of treated birds. This study highlights that consumption equivalent to 1.8 % of the daily diet of baywings as IMI-treated seeds, is sufficient to generate behavioral and physiological alterations and death. In the wild, these effects may have ecological consequences, by impairing the survival of birds, representing a risk to farmland bird populations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The present study examined the acute and chronic toxicity attributed to commercial formulations of the anthranilic diamide insecticides chlorantraniliprole (CHLO) and cyantraniliprole (CYAN) on the neotropical amphibian species Rhinella arenarum , Rhinella fernandezae and Scinax granulatus . The median lethal concentrations obtained after 96 hr exposure (96 hr-LC 50 ) were generally greater than 100 mg/L, except for stage 25 S. Granulatus , which were the most sensitive animals tested with a 96 hr-LC 50 value of 46.78 mg/L. In subchronic exposures of R. arenarum , the 21day-LC 50 were 151.4 mg/L for CHLO and >160 mg/L for CYAN, the weight gain of the tadpoles during this period not being markedly affected in both cases. Finally, when tadpoles of R. arenarum were exposed to CHLO throughout the metamorphic process, an inverted U-shaped non-monotonic dose-response relationship was observed between exposure concentrations and both % of individuals transiting between stage 39 and 42 and the time required to accomplish this. Data obtained raise the hypothesis of an effect of CHLO on the hypothalamic-pituitary-thyroid (HPT) axis, either directly or through an interaction with the stress-hormone system, as metamorphic progression from stage 39 to S42 occurs under the strict control of thyroid hormones. These observations are important as the anthranilic diamide insecticides are not currently known as endocrine disruptors. Further investigations are needed to clarify the pathways leading to these effects and examine whether environmentally-relevant aquatic concentrations of anthranilic diamides might be impacting amphibian populations in the wild.

The goal of the present study was to examine the effects of environmentally relevant concentrations of the neonicotinoid insecticides thiamethoxam and imidacloprid on the metamorphosis of the toad Rhinella arenarum. Tadpoles were exposed from stage 27 until completion of metamorphosis to concentrations of thiamethoxam ranging between 1.05 and 1050 µg/L and concentrations of imidacloprid varying between 3.4 and 3400 µg/L. The two neonicotinoids were found to act differently at the range of concentrations tested. Thiamethoxam did not markedly alter the final % tadpoles completing metamorphosis but extended by 6-20 days the time needed for tadpoles to complete metamorphosis. The extra number of days required to reach metamorphosis was concentration-dependent between 1.05 and 100.5 µg/L, and then stable at 20 days between 100.5 and 1005 µg/L. In contrast, imidacloprid did not significantly interfere with the overall time needed to complete metamorphosis but decreased success of metamorphosis at 3400 µg/L, the highest concentration tested. Both neonicotinoid concentrations did not markedly alter body size and weight of the newly metamorphosed toads. With a lowest observed effect concentration (LOEC) of 1.05 µg/L, thiamethoxam may be more likely to impact tadpole development in the wild compared to imidacloprid, which was without any apparent effect at concentrations up to 340 µg/L (no-observed effect concentration or NOEC). As the influence of thiamethoxam was triggered after tadpoles had reached Stage 39, when metamorphosis is strictly dependent upon thyroid hormones, this observed effect is attributed to result from actions of this neonicotinoid insecticide on the hypothalamic-pituitary-thyroid axis.

Neonicotinoids are globally used insecticides, and there are increasing evidence on their negative effects on birds. This study is aimed at characterizing the behavioral and physiological effects of the neonicotinoid imidacloprid (IMI) in a songbird. Adults of Agelaioides badius were exposed for 7 days to non-treated peeled millet and to peeled millet treated with nominal concentrations of 75 (IMI1) and 450 (IMI2) mg IMI/kg seed. On days 2 and 6 of the trial, the behavior of each bird was evaluated for 9 min by measuring the time spent on the floor, the perch, or the feeder. Daily millet consumption, initial and final body weight, and physiological, hematological, genotoxic, and biochemical parameters at the end of exposure were also measured. Activity was greatest on the floor, followed by the perch and the feeder. On the second day, birds exposed to IMI1and IMI2 remained mostly on the perch and the feeder, respectively. On the sixth day, a transition occurred to sectors of greater activity, consistent with the disappearance of the intoxication signs: birds from IMI1 and IMI2 increased their time on the floor and the perch, respectively. Control birds always remained most of the time on the floor. IMI2 birds significantly decreased their feed intake by 31% the first 3 days, compared to the other groups, and significantly decreased their body weight at the end of the exposure. From the set of hematological, genotoxic, and biochemical parameters, treated birds exhibited an alteration of glutathione-S-transferase activity (GST) in breast muscle; the minimal effects observed are probably related to the IMI administration regime. These results highlight that the consumption of less than 10% of the bird daily diet as IMI-treated seeds trigger effects at multiple levels that can impair bird survival., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Although pesticides are used intensively in Argentina's Pampa region, the possibility of performing an environmental risk assessment (ERA) remains limited due to the absence of readily available databases to run pesticide fate models and the lack of standardized realistic worst-case scenarios. The aim of the present study was to further advance capacities for performing probabilistic ERAs in the Pampa region by dividing and parameterizing the region into functional soil-climate mapping units (SCU) and defining statistically based, worst-case soil-climate exposure scenarios. Results obtained demonstrate that the SCU selected for a specific modeling exercise should depend on the dissociation constant (K d ) of the pesticide evaluated and whether short- or long-term pesticide fate modeling and risk assessment are needed. Four regionally representative SCUs were specifically identified for modeling the fate of pesticides with low, high, and intermediate values of K d . Fate modeling of pesticides with an intermediate K d requires the use of a different SCU for short- versus long-term pesticide modeling, whereas this distinction is not necessary for pesticides with both low and high K d . The current definition of realistic, worst-case, soil-climate scenarios represents a crucial step toward better pesticide fate modeling and exposure assessment in Argentina's Pampa region. Integr Environ Assess Manag 2023;19:626-637. © 2022 SETAC., (© 2022 SETAC.)

The new questions in ecotoxicology highlight the importance of applying a battery of biomarkers, as this results in ecotoxicological predictions that improve not only the interpretation of the effects of environmental stressors on organisms but also the determination of their possible impact. It is well known that the use of ecotoxicological biomarkers at different levels of organization allows for the prediction of the biological responses of organisms to environmental stressors, which is useful in environmental risk assessment. Nevertheless, it is necessary to consider the optimization of basic procedures, to generate historical data in control groups, and to employ specific bioassays to evaluate responses in organs and tissues in order to elucidate the nature and variation of the effects observed. Therefore, the present work aims to describe several ecotoxicological methodologies employed in all stages of neotropical anurans at different ecological levels and to validate them as useful biomarkers to be used both in wildlife and in laboratory conditions. In this work, these biomarkers were applied at the individual/organismic level (body condition index), histological/physiological level (histopathology, histometric, and pigmentary analyses), biochemical level (oxidative stress enzymes), and genetic level (direct and oxidative damage in DNA by comet assay). Although these methodologies have small variations or modifications depending on the species, these techniques provide effective biomarkers for evaluating the effect of xenobiotics on anurans, which possess certain characteristics that make them useful indicator species of aquatic and terrestrial ecosystems. In conclusion, the battery of biomarkers employed in the present study has proven to be adequate for estimating toxic responses in Neotropical anurans and can be further recommended as bioindicators for identifying the impact of pollutants on the aquatic ecosystems of the region. Finally, it is recommended to achieve the standardization of these important biomarkers for anurans in specific regions as well as to possibly include them in risk assessments and decision-making.

Imazethapyr, a post-emergent herbicide used in worldwide soybean and corn crops, induces genetic and biochemical alterations in aquatic vertebrates. This study examined the relationship between biomarkers at different organization levels and imazethapyr real-life route exposure in Boana pulchella adults. Frogs were exposed to imazethapyr-based formulation Pivot ® H (10.59%) at concentrations representing possible acute routes: field runoff (S1:10 mg.L -1 ), exposure after direct foliar application (S2:100 mg.L -1 ) and during direct foliar application (S3:1000 mg.L -1 ). Post-exposure, endpoints levels were evaluated: organism alterations, biochemical activities and cytogenetic assays. Forty-eight hours post-exposure, antioxidant enzymes decrease, micronuclei induction and DNA damage were observed in all scenarios, while cholinesterase activity increase and body condition reduction were observed in frog-exposed to S3. Ninety-six hours post-exposure, frogs showed glutathione-S-transferase inhibition in S1, micronuclei induction in S2 and S3, and DNA-damage increase in S3. Herbicides routes of exposures in real-life could indicate that authorized applications have a risk to amphibian populations., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Industrial, agricultural, and urban areas can be sources of pollution and a cause of habitat fragmentation. The Conlara River located in the northeast of San Luis Province suffers different environmental pressures along its course from urban to agro-industrial areas. The present study aims to assess the water quality of the Conlara basin by evaluating how metals and pesticide contamination as well as physicochemical parameters relate to physiological stress in Jenynsia multidentata . Samplings were carried out in four sites characterized by a growing gradient of anthropic impact from the springs to the final sections of the river, starting with tourism passing through urban areas and ending with large agricultural areas (from S1 to S4) during both the dry and wet seasons. A total of 27 parameters were determined (11 physicochemical, 9 heavy metals, and 7 pesticides) in surface waters. Biomarkers (CAT, TBARS, ChE, and MN) showed significant physiological and cytological alterations in J. multidentata depending on the hydrology season. The combination of physicochemical parameters, metals, and pesticide levels allowed typification and differentiation of the sites. Some metal (Cr, Mn, Pb, and Zn) and pesticide (α-BHC, chlorpyrifos, permethrin and cypermethrin, and endosulfan α) levels recorded exceeded the recommended Argentinian legislation values. A principal component analysis (PCA) allowed detection of differences between both seasons and across sites. Furthermore, the differences in distances showed by PCA between the sites were due to differences in the presence of physicochemical parameters, metals, and pesticides correlated with several biomarkers' responses depending on type of environmental stressor. Water quality evaluation along the Conlara River shows deterioration and different types of environmental stressors, identifying zones, and specific sources of pollution. Furthermore, the biomarkers suggest that the native species could be sensitive to anthropogenic environmental pressures.

The present study examined the acute and chronic toxicity of the neonicotinoid insecticides imidacloprid (IMI) and thiamethoxam (TIA) on the neotropical amphibian species Rhinella arenarum, Rhinella fernandezae and Scinax granulatus. The median lethal concentration after 96 hr exposure (96 hr-LC 50 ) ranged between 11.28 and >71.2 mg/L amongst all species and development stages tested, indicating that these pesticides are not likely to produce acute toxicity in the wild. The subchronic toxicity was also low, with 21 day-LC 50 values ranging between 27.15 and >71.2 mg/L. However, tadpoles of Rhinella arenarum exposed to thiamethoxam from stage 27 until completion of metamorphosis presented a significantly lower metamorphic success rate together with a smaller size at metamorphosis, starting from the lowest concentration tested. Although a number of studies previously examined the effects of neonicotinoids on amphibian tadpoles, these investigations focused on the time to metamorphosis and reported a variety of results including retardation, acceleration or lack of effect. Here, data demonstrated that thiamethoxam predominantly impacts metamorphosis through reduction of the transformation success and body weight, rather than by affecting the timings of metamorphosis. By closely monitoring progression of tadpoles through the different stages, impairment of metamorphosis was demonstrated to occur during the transition from stage 39 to 42, suggesting an effect on the thyroid system. An asymmetry in the length of the arms was also observed in metamorphs treated with thiamethoxam. Overall, these results indicate that thiamethoxam, and conceivably other neonicotinoids, have the potential to significantly impair metamorphosis of amphibians and diminish their performance and survival in the wild.

Contamination with current-use pesticides is frequently mentioned as a key factor in global amphibian declines although a limited number of studies have examined the mixture of pesticides accumulated by free-living frogs. This study examined the presence of 46 different pesticide residues in the muscle and kidney tissues of two frog species living in close association with row crops in the Pampa region of Argentina: The terrestrial Leptodactylus latinasus and the semi-aquatic Leptodactylus latrans. A total of 20 different pesticides were identified in frog tissues; chlorpyrifos-methyl, pirimiphos-methyl and acetochlor being the most frequently detected molecules. Overall, one or more pesticide residues (up to 12 in a single frog) were detected in 40-57 % of L. latrans. L. latinasus was found to present more pesticide detections than L. latrans. Interestingly, frog sampled in a natural reserve where no pesticides are applied presented an equivalent frequency of detections as frogs living near a crop. In L. latrans, the calculation of a pesticide toxicity index (PTI) permitted to highlight the existence of a strong positive correlation between PTI and liver GSH contents of females whereas, in males, PTI was negatively correlated with the perimeter of testicular seminiferous tubules. Males also presented near significant negative correlations between PTI and both body condition and the scaled fat index. These results indicate that frogs inhabiting agricultural regions are exposed to a complex and diffuse contamination by pesticide mixtures which is likely responsible for a number of biological effects that may be relevant at the population level., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The neonicotinoids are globally used insecticides, which have been shown to cause negative impacts on birds. The current study aimed to evaluate the distribution of the neonicotinoid imidacloprid (IMI) in the tissues of a songbird and identify related physiological effects. Adults of the grayish baywing (Agelaioides baduis) were administered with a single dose of 35 mg IMI/kg, and the IMI concentration was evaluated in liver, kidney and plasma at 4, 12, 24, and 48 h after dosing. At the same time points, effects on hematological, genetic and enzymatic parameters were assessed. Results showed that IMI was absorbed before 4 h, and eliminated at 48 h, in every tissue, and the highest concentrations were detected in plasma. Baywings showed intoxication signs and reduced mobility within the first 5 min post-dosing. Hematological parameters: red blood cells, packed cell volume, hemoglobin, and their derived indices exhibited a transient elevation 24 h after dosing, which coincided with maximum concentrations of IMI in the tissues. No effects were observed on the genotoxicity parameters evaluated: micronuclei and comet assay. Treated birds exhibited an alteration of cholinesterases activity in the muscle and plasma, and of glutathione-S-transferase (GST) activity in the plasma, brain, liver, and muscle. Based on the results obtained, the combined detection of IMI and inhibition of GST activity in the plasma is suggested as a non-lethal biomarker of IMI exposure in wild birds. As efficient field monitoring depends on the availability of proven biomarkers, the current study provides valuable tools for bird conservation in agroecosystems., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Imazethapyr is an herbicide that is used in a variety of crops worldwide, including soybean and corn. The aim of the present study was to evaluate the biomarkers responses of adult Leptodactylus latinasus exposed to the formulation Pivot ®  H (10.59% imazethapyr) in the laboratory at concentrations and under conditions that simulate two potential field exposure scenarios: an immersion in field runoff (Scenario 1: 10 mg/L) and a direct exposure to the droplets emitted by spray noozles (Scenario 2: 1000 mg/L). In both scenarios, the experimental procedure involved completely immersing the frogs over a period of 15 s. Different endpoints were evaluated at several ecotoxicological levels 48 and 96 h after the herbicide exposure. These included individual (biometric indices and behavior alterations), histological (liver pigments and lesions), biochemical (catalase, glutathione system and cholinesterase activities) and genotoxic effects (micronuclei induction and nuclear abnormalities). Forty-eight hours after imazethapyr exposure, frogs submitted to Scenario 1 presented an inhibition of liver glutathione-S-transferase activity, whereas histological alterations and increased hepatic cholinesterase levels were observed in frogs exposed under Scenario 2. Ninety-six hours after exposure to the imazethapyr formulation, frogs from the Scenario 1 treatment presented a decrease in liver melanin and hemosiderin, increased hepatic catalase activity and micronuclei induction. For their part, frogs exposed to Scenario 2 presented a decrease in the hepatosomatic index, an increase in liver alterations, melanin reduction and micronuclei induction. The multivariate analysis enables correlations to be made between biomarkers of different organizational level in exposed anurans. Our result indicates that real exposure to imazethapyr formulations under field conditions may pose a risk to Leptodactylus latinasus populations living in the agroecosystems., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The aim of this study was to estimate the risk posed by imidacloprid (IMI) seed coating to passerine birds of the Pampa Region of Argentina using data specifically generated with the grayish baywing (Agelaioides badius). Median lethal dose (LD 50 ) of the IMI-based formulation tested was 57.11 mg IMI/kg body weight (bw), with intoxication signs starting from 20.6 mg IMI/kg bw. The feed intake rate (FIR) was estimated experimentally as 4.895 g/day per bird, representing 12.43% of bw. It was calculated that the ingestion of 7-10% of the FIR as treated seeds would be enough to achieve the LD 50 for sorghum, corn, sunflower, and alfalfa, whereas consumption of 31 and 54% of FIR was necessary for oat and wheat, respectively. Based on spill data values available in the literature, it was calculated that, for most crops, a baywing would have to forage an area of field corresponding to less than 60 m 2 to obtain the number of seeds required to reach the LD 50 . It was also shown that this number of seeds is coherent with the amount of seeds ingested in a bout. In a pilot study, all grayish baywings fed with millet seeds treated with 3 g IMI/kg died within three to five days of exposure. In Tier I risk assessment, the trigger value was achieved for all crops except soybean and a weight-of-evidence risk assessment was performed. All lines of evidence examined are consistent with the view that grayish baywings, and probably other small farmland birds, are exposed to a risk of acute toxicity and mortality under both worst-case and mixed-ration exposure scenarios. The possible impacts on bird species calls for an urgent reconsideration of IMI seed coating practices currently approved in the Pampa Region of Argentina and the various parts of the world where this practice is still in use., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This paper presents the first acute toxicity data of the natural insecticide spinosad in amphibians. The sensitivity of two neotropical sympatric anuran species, Boana pulchella and Rhinella arenarum, to spinosad-based formulation Tracer™ was evaluated. Lethal effects are reported in tadpoles of B. pulchella stage 25 between 2.81 and 35.44 mg spinosad/L, while for the same concentration range no lethal effects were detected in tadpoles of R. arenarum of the same stage. In addition, Tracer™ produced sublethal effects at the individual level on the swimming activity, morphology (growth and presence of abnormalities), and development of B. pulchella from 2.81 to 5.78 mg spinosad/L, while in R. arenarum effects were only detected in the swimming activity and growth from 2.78 and 6.22 mg/L, respectively. At the biochemical level, Tracer™ produced inhibition of different enzymatic activities, among them, catalase activity at 2.81 mg spinosad/L, glutathione S- transferase activity from 2.81 to 2.98 mg spinosad/L, and acetylcholinesterase activity at 2.81 mg spinosad/L. These findings allow us to conclude that B. pulchella is more sensitive than R. arenarum to spinosad-based formulation Tracer™. The effects demonstrated here are not consistent with those expected since spinosad is supposed to be an environmental healthy alternative. This paper provides useful and necessary information to implement regulations on the use of new compounds entering the market and its associated risks.

The safety of creating fish farms in agricultural settings was evaluated by growing Piaractus mesopotamicus in a pond, while crops where cultivated in a nearby field under a pesticide application regime typical of the Pampa region. Atrazine, glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), were detected in the water of the pond at concentrations ranging between 92 and 118 μg/L for atrazine, 12 and 221 μg/L for glyphosate and 21 and 117 μg/L for AMPA. Atrazine and malathion were detected in fish muscles at concentrations ranging between 70 and 105 μg/kg for atrazine and 8.6 and 23.7 μg/kg for malathion. Compared to fish raised in a pisciculture, fish from the agricultural pond presented reduced values of pack cell volume, hemoglobin, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration, together with significantly greater cholinesterase activity in both plasma and liver and reduced glutathione-S-transferase activity in the liver. A comet assay also demonstrated that P. mesopotamicus from the agricultural pond presented a significantly greater level of DNA damage in both erythrocytes and gill cells. Overall, the present study demonstrates that pisciculture ponds established in an agricultural setting may receive pesticides applied to nearby cultures and that these pesticides may be taken up by the fish and affect their physiology and health. The accumulation of pesticides residues in fish flesh may also present a risk to human consumers and should be closely controlled., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In the context of the global amphibian crisis, biomonitoring constitutes a valuable assessment tool to provide critical up to date information on the status and health of amphibians worldwide. The aim of the current study was to evaluate the possible confounding effects of sex, size, and time since capture on enzymatic biomarkers and hematologic parameters of the South American frog Leptodactylus latrans. Frogs were collected by hand between 9 pm and 12 am on two consecutive nights. On the first night, captured frogs were transported for 2 h by car to laboratory installations, maintained overnight in plastic containers, and blood and tissue sampled on the next morning. In contrast, frogs collected on the second night were blood and tissue sampled in the field, immediately after the capture period. Hematological parameters were analyzed, and enzymatic activities of catalase, cholinesterase (ChE), and glutathione S-transferase (GST) were determined in the plasma, liver, kidney, and muscle. A sex difference was observed only for total white blood cell counts (WBC), females exhibiting significantly greater values than males. The packed cell volume (PCV), mean corpuscular hemoglobin concentration (MCHC), WBC, and muscle ChE activity were significantly correlated with snout-vent length (SVL). The correlation was inversed in the case of MCHC, WBC, and muscle ChE, while the correlation was positive between PCV and SVL. Most examined parameters presented similar values when frogs were sampled at night following capture or the next morning. Total red blood cells (RBCs) count, and plasma enzymatic activities of ChE and GST were the only parameters that presented significantly increased values in morning samplings compared with night samplings. Overall, the current study indicates that it is best to sample the frogs as soon as possible after capture if hematologic or plasmatic biomarkers are examined. Nevertheless, it is possible to sample on the next morning if tissular biomarkers are employed.

Glyphosate (GLY)-dicamba (DIC) and GLY-flurochloridone (FLC) are herbicide mixtures which are widely used for treating fallow containing glyphosate resistant weeds. The aim of this study was to evaluate the acute toxic effects and the prevailing interactions on stage 36 tadpoles of the anuran species Rhinella arenarum when exposed to equitoxic and non-equitoxic combinations of these herbicide combinations. Experiments were realized using the following combinations of commercial formulations: 48% GLY-based Credit® + 57.71% DIC-based Banvel® and 48% GLY-based Credit® + 25% FLC-based Twin Pack Gold®. GLY-DIC and GLY-FLC equitoxic mixtures were assayed mixing each constituent with an equivalent individual toxicity able to induce the same lethality effect. After 96 h of exposure, GLY-DIC and GLY-FLC equitoxic mixtures presented toxic unit 50 values (TU 50 96h ) of 1.74 (confidence interval: 1.58-1.92) and 1.54 (confidence interval: 1.46-1.62) respectively, indicating the presence of a weak antagonistic interaction as TU values were greater than 1. For their part, most non-equitoxic combinations of GLY-DIC and GLY-FLC tested did not significantly differ from additivity, the only exception being when DIC and FLC were fixed at 0.33 TUs, where a weak antagonism was observed. Overall, results indicate that the toxicity of both GLY-DIC and GLY-FLC mixtures to R. arenarum tadpoles vary from additive to slightly antagonistic, depending on the proportion of constituting herbicide formulations present in the mixture., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Genotoxic, biochemical, and individual organizational effects on Leptodactylus latinasus tadpoles were evaluated after exposure to an imazethapyr (IMZT)-based commercial herbicide formulation, Pivot® H (10.59% IMZT). A determination of the value of the lethal concentration (LC50) was determined as a toxicological endpoint. Alterations in animal behavior and morphological abnormalities as well as cholinesterase (ChE), catalase (CAT), and glutathione S-transferase (GST) activities were employed as individual sublethal endpoints. Micronuclei frequencies (MNs), binucleated cells (BNs), blebbed nuclei (BLs), lobed nuclei (LBs), notched nuclei (NTs), erythroplastids (EPs), and evaluation of DNA strand breaks were employed as genotoxic endpoints. All biomarkers were evaluated after 48 and 96 h of exposure to concentrations of IMZT within 0.07-4.89 mg/L. LC50 96h values of 1.01 and 0.29 mg/L IMZT were obtained for Gosner stages 25 and 36, respectively. Irregular swimming, diamond body shape, and decreased frequency of keratodonts were detected at both sampling times. Results showed that IMZT increased GST activity and MN frequency at 48 and 96 h of exposure. Other nuclear abnormalities were also observed in the circulating erythrocytes of tadpoles, i.e., NT and BL values after 48 h, and LN, BL, and EP values after 96 h. Finally, results showed that IMZT within 0.07-0.22 mg/L increased the genetic damage index in tadpoles exposed for both exposure times (48 and 96 h). This study is the first to report the sublethal biochemical effects of IMZT in anurans and is also the first report using L. latinasus tadpoles as a bioindicator for ecotoxicological studies.

Despite the widespread use of pesticides in the Pampa region of Argentina, mathematical models are rarely employed to predict pesticide fate due to the lack of regionally tested models and the absence of readily available databases to run such models. The objective of the current study was to perform a sensitivity analysis of the Pesticide in Water Calculator (PWC) model for the Pampa Region of Argentina. The sensitivity analysis was performed while simulating applications of 2,4-D (mobile, low Kd) and glyphosate (soil-binding, high Kd) in five localities of the Pampa region: Anguil, Paraná, Marcos Juárez, Pergamino and Tres Arroyos. The sensitivity of the various parameters involved in PWC modelling was evaluated though a two-steps sensitivity analysis which included a first screening of less sensitive parameters with Morris method, followed by a fully global sensitivity analysis of the remaining parameters using Sobol method. When ran under soil and climate conditions typical of the Pampa region of Argentina, PWC was most sensitive to 25% of the parameters evaluated. The sensitive parameters identified depended mainly on the nature of the pesticide molecule being modelled; the location and endpoint considered having much less influence on the sensitivity results. Sensitive parameters belonged to two main grand categories: (i) degradation rates of the pesticide in soil and water, and (ii) parameters descriptive of soil binding, runoff and erosion. The sensitivity analysis of the model PWC performed in the current study represents a crucial first step towards the development and expansion of probabilistic pesticide risk assessment in Argentina, and provides important parameterization criteria that will help obtaining more certain modelling results from PWC in Argentina and elsewhere., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Neonicotinoids have recently been demonstrated to cause direct negative impacts on birds from North America and Europe. To further understand the impact of these compounds on bird species and to improve risk assessment capacities, the current study determined the acute toxicities of imidacloprid, clothianidin, and thiamethoxam formulations on South American eared doves (Zenaida auriculata). Insecticides were administered by gavage to adult doves to determine median lethal doses (LD50) according to a standardized sequential procedure. The acute toxicity of formulated imidacloprid (LD50=59mg active ingredient, a.i./kg body weight, b.w.) was much higher than that of the tested formulations of clothianidin (LD50=4248mga.i./kg b.w.) and thiamethoxam (LD50=4366mga.i./kg b.w.). Imidacloprid also differed from the other two neonicotinoids in terms of the onset and intensity of intoxication signs and the times of death and recovery. All three insecticides induced a reduction in food consumption that led to body weight loss. An average weight dove of 127g would obtain a dose equivalent to the LD50 of imidacloprid by consuming 1.7g of treated sorghum seeds. As eared doves offered non-treated sorghum seeds 5h per day consumed on average 6.4±1.8g (mean±S.D.), it is concluded that these doves could feasibly be exposed to lethal doses in the field. This work is the first to describe intoxication signs and report oral neonicotinoid LD50s in a wild South-American bird species., (Copyright © 2018. Published by Elsevier B.V.)

The aim of this study was to characterize the level and nature of the pesticide contamination received by one-sided livebearer fish (Jenynsia multidentata) from a watercourse situated within the main agricultural region of Argentina, and to assess the effects of this contamination on fish health. Juvenile one-sided livebearer fish (Jenynsia multidentata) were collected in December 2011 and March 2012 from three sites along the Pergamino River. Pesticide contamination was characterized by extracting whole fish and analytically determining thirty different pesticide molecules. The biomarkers catalase, glutathione-S-transferase, and cholinesterases were assessed. Body condition was calculated as an estimate of the amount of energy reserves possessed by the fish. Seventeen different pesticides were detected in fish tissues with 81% of captured animals containing at least one pesticide molecule. The pyrethroid insecticides fenvalerate and bifenthrin were most frequently detected, being respectively found in 41.8 and 36.4% of samples tested. Highly toxic dichlorvos and pirimiphos-methyl were detected. Differential levels of contamination could not be established amongst sites but were observed within sites amongst the two sampling dates. The months when pesticide residues were most abundant from in Site A and B corresponded to the months when body condition was at its lowest in the two sites. The inhibition of Che activity in March when body condition was reduced also points to a role of insecticide contamination in the reduction of body condition. These findings provide strong new evidence that current-used agricultural pesticides can accumulate in wild fish and impact their health and energetics., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Although pesticide contamination of surface waters normally occurs in the form of mixtures, the toxicity and interactions displayed by such mixtures have been little characterized until now. The present study examined the interactions prevailing in equitoxic and non-equitoxic binary mixtures of formulations of glyphosate (Glifoglex(®)) and cypermethrin (Glextrin(®)) to the tenspotted livebearer (Cnesterodon decemmaculatus), a widely distributed South American fish. The following 96 h-LC50s were obtained when pesticide formulations were tested individually: Glifoglex(®) 41.4 and 53 mg ae glyphosate/L; Glextrin(®) 1.89 and 2.60 μg cypermethrin/L. Equitoxic and non-equitoxic mixtures were significantly antagonic in all combinations tested. The magnitude of the antagonism (factor by which toxicity differed from concentration addition) varied between 1.37 and 3.09 times in the different non-equitoxic mixtures tested. Antagonism was due to a strong inhibition of cypermethrin toxicity by the glyphosate formulation, the toxicity of the cypermethrin-based pesticide being almost completely overridden by the glyphosate formulation. Results obtained in the current study with fish are radically opposite to those previously observed in tadpoles where synergy was observed when Glifoglex(®) and Glextrin(®) were present in mixtures (Brodeur et al., 2014)., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The herbicide glyphosate and the insecticide cypermethrin are key pesticides of modern management in soy and corn cultures. Although these pesticides are likely to co-occur in ephemeral ponds or aquatic systems supporting amphibian wildlife, the toxicological interactions prevailing in mixtures of these two pesticides have been little studied. The current study evaluated the toxicity of equitoxic and non-equitoxic binary mixtures of glyphosate- and cypermethrin-based pesticides to tadpoles of the common South American toad, Rhinella arenarum. Two different combinations of commercial products were tested: glyphosate Glifosato Atanor®+cypermethrin Xiper® and glyphosate Glifoglex®+cypermethrin Glextrin®. When tested individually, the formulations presented the following 96 h-LC50s: Glifosato Atanor® 19.4 mg ae L(-1) and Glifoglex 72.8 mg ae L(-1), Xiper® 6.8 mg L(-1) and Glextrin® 30.2 mg L(-1). Equitoxic and non-equitoxic mixtures were significantly synergic in both combinations of commercial products tested. The magnitude of the synergy (factor by which toxicity differed from concentration addition) was constant at around twofold for all tested proportions of the glyphosate Glifoglex®+cypermethrin Glextrin® mixture; whereas the magnitude of the synergy varied between 4 and 9 times in the glyphosate Glifosato Atanor®+cypermethrin Xiper® mixture. These results call for more research to be promptly undertaken in order to understand the mechanisms behind the synergy observed and to identify and quantify the extent of its environmental impacts., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Despite of the various studies reporting on the subject, anticipating the impacts of the widely-used herbicide atrazine on anuran tadpoles metamorphosis remains complex as increases or decreases of larval period duration are almost as frequently reported as an absence of effect. The aim of the present study was to examine the effects of environmentally-relevant concentrations of atrazine (0.1, 1, 10, 100, and 1000μg/L) on the timings of metamorphosis and body size at metamorphosis in the common South American toad, Rhinella arenarum (Anura: bufonidae). None of the atrazine concentrations tested significantly altered survival. Low atrazine concentrations in the range of 1-100μg/L were found to accelerate developmental rate in a non-monotonic U-shaped concentration-response relationship. This observed acceleration of the metamorphic process occurred entirely between stages 25 and 39; treated tadpoles proceeding through metamorphosis as control animals beyond this point. Together with proceeding through metamorphosis at a faster rate, tadpoles exposed to atrazine concentrations in the range of 1-100μg/L furthermore transformed into significantly larger metamorphs than controls, the concentration-response curve taking the form of an inverted U in this case. The no observed effect concentration (NOEC) was 0.1μg atrazine/L for both size at metamorphosis and timings of metamorphosis. Tadpoles exposed to 100μg/L 17β-estradiol presented the exact same alterations of developmental rate and body size as those treated with 1, 10 and 100μg/L of atrazine. Elements of the experimental design that facilitated the detection of alterations of metamorphosis at low concentrations of atrazine are discussed, together with the ecological significance of those findings., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Parameters indicative of general condition and health were compared amongst adult frogs inhabiting uncultivated lands and fields subjected to agricultural practices typical of the humid pampas of Argentina. Whereas no significant differences existed in the parasite load and external malformations prevalence rate of adult frogs from either environments, a reduced condition factor was clearly demonstrated in frogs from agricultural lands. This conclusion was reached for four frog species of different life habits: the terrestrial fossorial Rhinella fernandezae, the terrestrial Leptodactylus latinasus, the semi-aquatic Leptodactylus ocellatus, and the arborescent Hypsiboas pulchellus. A distinct pattern of enzymatic modifications was furthermore observed in L. ocellatus and H. pulchellus from agricultural lands, including elevated hepatic activities of catalase and cholinesterase, and an inhibition of liver GST activity. Further studies should investigate the causes and consequences of the systematically low condition factor observed in frogs from agricultural fields of the humid pampas of Argentina., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Acute and subchronic toxicity of atrazine was evaluated in embryos (stage 4) and in premetamorphosis (stage 25) and prometamorphosis (stage 38-39) larvae of the common South American toad Rhinella arenarum (Anura: bufonidae). The influence of atrazine on the last stages of metamorphosis was also examined by exposing prometamorphosis larvae until completion of metamorphosis. Results obtained revealed that larvae in premetamorphosis are more sensitive than larvae in prometamorphosis and that these are, in turn, more sensitive than embryonic stages. Indeed, concentrations of atrazine as high as 30 mg/L had little effects on embryonic stages, the embryos surviving and developing in a similar manner as controls. LC50s of premetamorphosis larvae equaled 27.16, 7.03 and 2.32 mg/L of atrazine after 4, 14 and 21 days of exposure, respectively, compared to LC50s values of 18.27 and 14.43 mg/L after 14 and 21 days of exposure for larvae in prometamorphosis. In experiments with premetamorphosis larvae, the range of tested concentrations was extended to very low concentrations (down to 0.0001 mg/L) to examine whether recent findings of greater mortality at lower doses than at higher doses were also observed in R. arenarum but no such pattern was found. Exposure of prometamorphosis larvae to concentrations of atrazine of 10 mg/L and above widely prevented completion of metamorphosis and caused important mortality. Alternatively, whereas all animals eventually completed metamorphosis when exposed to concentrations of atrazine between 0.1 and 5 mg/L, the timings of metamorphosis were altered starting from 0.1 mg/L, the lowest concentration tested. Indeed, a significant decrease in the time needed for 50% of the larvae to reach the metamorphic climax (stage 42) was observed within this range of atrazine concentrations, the response presenting a U-shaped non-monotonic dose-response curve. Larvae exposed to these concentrations of atrazine also needed significantly more time for completing tail resorption, this effect being equivalent at all concentrations. Overall, the combination of these two different facets of atrazine influence on metamorphosis resulted in a significant acceleration of metamorphosis at 1 mg/L and a significant increase in the duration of metamorphosis at 5 mg/L, whereas no significant difference was observed with 0.1 mg/L.

The current study evaluated acute and subchronic toxicity of arsenite (As(3+)) and zinc (Zn(2+)) to stage 25 tadpoles of Rhinella arenarum in both single and joint laboratory exposures. LC50 values obtained for As(3+) were elevated and remained within the range of 46 to 50 mg/L of As(3+) between 4 and 17 d of exposure. Growth of tadpoles was completely inhibited with 30 mg/L of As(3+), demonstrating the presence of ecologically relevant sublethal effects at concentrations lower than those resulting in lethality. With respect to Zn(2+), a 96-h LC50 value of 2.49 mg/L was calculated in soft water. Contrary to results obtained for As(3+), LC50 values of Zn(2+) gradually decreased with increasing exposure duration, from 2.49 mg/L at 96 h to 1.30 mg/L after 21 d. In joint exposures to both metals, the type of interaction observed between As(3+) and Zn(2+) was concentration dependent. Lethal effects of As(3+) were mitigated, unaffected, or potentiated by 0.01, 0.1, and 1-2 mg/L of Zn(2+), respectively. However, although 0.01 mg/L of Zn(2+) significantly reduced lethality of As(3+)-exposed tadpoles, the same concentration of Zn(2+) did not help to reverse the stunt growth of these animals. Further studies need to examine which are the lowest concentrations As(3+) required to reduce growth and whether Zn(2+) serves to antagonize growth effects in this range of concentrations.

The present study compared three different methods for measuring plasma vitellogenin (VTG) in fathead minnow (FHM; Pimephales promelas): A procedure using liquid chromatography with electrospray ionization combined with tandem mass spectrometry (LC/ESI-MS/MS), and two commercial enzyme-linked immunoassay (ELISA) kits using either anti-carp or anti-FHM antibodies. The influence on plasma VTG measurements of using the protease-inhibitor aprotinin during blood sampling and of submitting the plasma samples to a freeze-thaw cycle before analysis also was evaluated. The addition of aprotinin to the blood during sampling significantly reduced the plasma VTG concentrations measured by ELISA, whereas the VTG values measured after plasma samples were submitted to a freeze-thaw cycle were significantly higher than those measured before freezing. This inflating effect of freezing on VTG measurements made by ELISA could be prevented if plasma samples were frozen diluted in citrate buffer containing 16 mg/ml of polyethylene glycol (PEG). In contrast, measurements of VTG made by LC/ESI-MS/MS were unaffected by freezing and, conceptually, are independent from enzymatic degradation. Although the use of aprotinin and PEG effectively reduced the influence of enzymatic and physical degradation caused by freezing and thawing on VTG measurements made by ELISA, it did not improve agreement between the three analytical techniques evaluated. More information is needed regarding the molecular structure and the existence of possible multiple forms of VTG before this protein can be measured adequately in FHM.

The effects of elevated plasma cortisol levels on vitellogenin (VTG) induction were examined in the fathead minnow (Pimephales promelas) in an attempt to evaluate the potential influence of stress on this commonly used biomarker of estrogenicity. Two separate experiments were conducted in which fish plasma cortisol was elevated to various levels for 14 d by noninvasive additions of cortisol to the aquaria water. Fathead minnows were exposed to either cortisol alone, 17alpha-ethinylestradiol (EE2) alone, or a combination of the two hormones, and plasma levels of VTG as well as liver expression of VTG mRNA were measured. Both experiments gave similar results, with an exposure to 4 ng/L of EE2 resulting in significantly greater levels of plasma VTG in the presence of, compared to that in absence of, cortisol, whereas exposure to cortisol alone at concentrations between 144 and 800 microg/L had no effect on plasma VTG levels. This potentiation of the EE2-induced vitellogenesis by cortisol was dose-dependent, with plasma VTG reaching 125, 167, and 295% of the values obtained with EE2 alone when 144, 360, and 800 microg/L of cortisol, respectively, were added to the water. Liver mRNA results were consistent with plasma VTG, although they generally were more variable. The present study demonstrates that cortisol does not independently induce vitellogenesis but can potentiate estrogen-induced VTG synthesis in fathead minnow. The implications of these findings for the use of VTG as a biomarker of estrogenicity are discussed.

Vitellogenin (VTG) has been proposed as a sensitive biomarker of exposure to environmental estrogenic contaminants that induce VTG production in oviparous species. Enzyme-linked immunosorbent assay (ELISA) methods are currently widely used to measure the VTG levels. In this paper, a new liquid chromatography combined with tandem mass spectrometry (LC/ESI-MS/MS) method for the quantitative analysis of VTG in the plasma of fathead minnows exposed to 17alpha-ethinylestradiol (EE2) has been developed. This method includes, first, the selection of the signature peptide, which involves sodium dodecyl sulfate-polyarylamide gel electrophoresis separation, in-gel digestion, LC/ESI-MS/MS analysis with an ion trap mass spectrometer, and sequence determination with the TurboSEQUEST MS/MS database application; second, optimization of the selected signature peptide in multireaction monitor (MRM) mode with a triple quadrupole mass spectrometer; and third, trypsin digestion of plasma and VTG quantitation via MRM-mode LC/ESI-MS/MS. A series of plasma samples from fathead minnows following exposure to EE2 was assayed. A good correlation was found when EE2-induced plasma samples from fathead minnows were analyzed with ELISA and the described new method. Although used here with fathead minnow, the new LC/ESI-MS/MS method could be easily applied to the analysis of VTG expressed in any other fish species. Quantitation of VTG by this method was found to be highly specific and linear. The absence of potential artifactual measurements of VTG at low exposure levels could also be critical in future studies that evaluate weakly estrogenic compounds in aquatic species.

A rapid and sensitive method for the analysis of 17alpha-ethinylestradiol (EE2) in environmental aqueous samples has been developed. Aquatic samples were extracted using liquid-liquid extraction, and organic phase extracts were concentrated and derivatized with dansyl chloride. Analysis was performed using high-performance liquid chromatography with positive electrospray ionization and tandem mass spectrometry (HPLC/ESI-MS/MS). Deuterated 17alpha-ethinylestradiol was used as internal standard and was added to samples before extraction. A limit of quantitation of 1 ng/L was obtained using a 25 mL aqueous sample. The average recovery of EE2 spiked into a 25 mL tapwater sample was 100%. This highly sensitive quantitation method is useful for measuring low levels of EE2 in aqueous environmental samples., (Copyright (c) 2004 John Wiley & Sons, Ltd.)

In teleosts, the proliferation of myogenic progenitor cells is required for muscle growth and nuclear turnover. We measured the cell cycle and S-phase duration of myogenic cells in the fast myotomal muscle of two closely related Harpagifer species by cumulative S-phase labelling with 5-bromo-2'-deoxyuridine (BrdU). Harpagifer antarcticus is a stenothermal species from the Antarctic peninsula (experiencing temperatures of -2 degrees C to +1 degrees C) and Harpagifer bispinis is a eurythermal species from the Beagle Channel, Tierra del Fuego (living at +4 degrees C in winter and up to 11 degrees C in summer). Specific growth rates in the adult stages studied were not significantly different from zero. Myogenic progenitor cells were identified using an antibody against c-met. Seventy-five percent of the c-met(+ve) cells were in a proliferative state in both species. Cell cycle time was 150 h at 5 degrees C and 81.3 h at 10 degrees C in H. bispinis (Q(10)=3.4). Cell cycle duration was 35% shorter in H. antarcticus at 0 degrees C (111 h) than in H. bispinis at 5 degrees C. The predicted cell cycle time for H. bispinis at 0 degrees C (based on the Q(10) relationship) was 277 h, which was more than double that measured for the Antarctic species at this temperature. The results obtained are compatible with an evolutionary adjustment of cell cycle time for function at low temperature in the Antarctic species.

Feeding metabolism and the activation of myogenic progenitor cells were investigated in the fast myotomal muscle of the sub-Antarctic fish Hapagifer bispinis acclimatized to either simulated summer (10 degrees C; 18 h:6 h light:dark) or simulated winter (5 degrees C; 6 h:18 h light:dark) conditions. Ingestion of a single meal equivalent to 10% and 15% of body mass in simulated winter and summer groups, respectively, resulted in an average 2.6-fold and 3.6-fold increase in oxygen consumption, declining to 75% of peak values after 63 h and 46 h. In fasted individuals, the number of myogenic progenitor cells, identified by the expression of c-met, was not significantly different between simulated summer and winter fish, representing 6.6% and 5.8% of total myonuclei, respectively. However, the number of cells expressing myogenin was higher whereas the expression of MyoD was lower in winter than in summer groups. The ingestion of a single meal under winter and summer treatment regimes resulted in a significant increase in the number of cells expressing MyoD (51% and 111%) and PCNA (88% and 140%, respectively). This was followed by an increase in the abundance of c-met (74 and 85%) and myogenin (42 and 97%, respectively) positive cells, indicating the production of new myogenic progenitor cells and the commitment to differentiation of a number of them. These results show that the proliferation of myogenic progenitor cells can be induced by feeding in teleost fishes and that temperature and photoperiod influence the expression of myogenic regulatory factors.

Rainbow trout (Oncorhynchus mykiss) were exposed for 24 h to concentrations representing 100, 50 and 25% of the 96 h-LC50 of pentachlorophenol (PCP) or tetrachloroguaiacol (TCG), and their oxygen consumption, cardiac output, heart rate and stroke volume were measured at regular intervals. Oxygen consumption either remained stable at basal levels (PCP), or increased to 130% of basal levels (TCG) when fish were exposed to the 96 h-LC50 of each chemical. However, oxygen consumption decreased to about 50-60% of basal levels when fish were exposed to concentrations of PCP or TCG representing 50 and 25% of the 96 h-LC50. This decrease in oxygen consumption did not appear to affect cardiac function since cardiac output, heart rate and stroke volume remained stable. PCP is best known for its capacity to uncouple oxidative phosphorylation and increase oxygen consumption. However, this study showed that it can also decrease oxygen consumption, and that the effects of PCP and TCG on fish metabolism are similar.

Atlantic salmon (Salmo salar) were exposed for 36 days to water from the acidified (pH 5.2) Fossbekk River (Norway) with 50 micro x L(-1) of aluminium (Al) added as AlCl(3), or to circumneutral water (pH 6.6) from Ims River (Norway). Food consumption, cardiac output, swimming activity, and growth rate were measured to determine the effects of sublethal levels of Al in acidic water on the bioenergetics of the fish. Food consumption was reduced in acidic water and Al during the first 12 days, but was not significantly different from the control group during the rest of the exposure. A significant decrease in body weight was concomitant with the reduction in food consumption. The fish also kept losing weight during the rest of the exposure despite the return of their appetite to normal. Cardiac output of the fish exposed to acidic water and Al was not significantly different from the control group after 36 days of exposure. Swimming activity remained significantly elevated throughout the exposure to acidic water and Al. These results indicate that sublethal levels of Al can alter the energy budget of Atlantic salmon living in acidified surface waters., (Copyright 2001 Academic Press.)