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In 2019, there was an environmental catastrophe in Brazil, when more than 5000 tons of unknown origin crude oil invaded beaches and mangroves. Two years later, two monitoring areas were selected to study seahorses' offspring: Massangana River estuary (apparently healthy area) and Cocaia Island (affected area). Thirty-six reproductive events of Hippocampus reidi (Syngnathidae) couples from these two areas were monitored to analyze the offspring. At the apparently healthy area, no newborns with malformations were found. However, the offspring from Cocaia Island showed a mean of 19.73% (±5.23) malformations in newborns. It is argued that the toxic/teratogenic effects of polycyclic aromatic hydrocarbons have affected the population in two ways: directly through the induction of mutations in the germ cells of the species and through a drastic reduction of the population (bottleneck effect) whose density observed today recovered through consanguineous couplings, potentiating deleterious genotypes in the offspring. Environ Toxicol Chem 2024;43:1996-2004. © 2024 SETAC.

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Pyriproxyfen (PPF), Bacillus thuringiensis israelensis (BTI), and malathion (MLT) are widely used worldwide to control the population of mosquitos that transmit arboviruses. The current work aimed to evaluate the toxicity of these single pesticides and their binary mixtures of PPF + BTI, PPF + MLT, and MLT + BTI on the embryo-larval stage of zebrafish (Danio rerio) as an animal model. Epiboly, mortality, apical endpoints, affected animals, heart rate, morphometric, thigmotaxis, touch sensitivity, and optomotor response tests were evaluated. PPF and MLT and all mixtures reduced the epiboly percentage. Mortality increased significantly in all exposed groups, except BTI, with MLT being the most toxic. The observed apical endpoints were pericardial and yolk sac edemas, and tail and spine deformation. Exposure to MLT showed a higher percentage of affected animals. A reduction in heart rate was also observed in MLT- and PPF + MLT-exposed groups. The PPF + MLT mixture decreased head measurements. Behavioral alterations were observed, with a decrease in thigmotaxis and touch sensitivity responses in PPF + MLT and MLT + BTI groups. Finally, optomotor responses were affected in all groups. The above data obtained suggest that the MLT + PFF mixture has the greatest toxicity effects. This mixture affected embryo-larval development and behavior and is close to the reality in several cities that use both pesticides for mosquito control rather than single pesticides, leading to a reevaluation of the strategy for mosquito control.

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To mitigate the environmental impact of microplastics (MPs), the scientific community has innovated sustainable and biodegradable polymers as viable alternatives to traditional plastics. Chitosan, the deacetylated form of chitin, stands as one of the most thoroughly investigated biopolymers and has garnered significant interest due to its versatile applications in both medical and cosmetic fields. Nevertheless, there is still a knowledge gap regarding the impact that chitosan biopolymer films (CBPF) may generate in aquatic organisms. In light of the foregoing, this study aimed to assess and compare the potential effects of CBPF on the gastrointestinal tract, gills, brain, and liver of Danio rerio against those induced by MPs. The findings revealed that both CBPF and MPs induced changes in the levels of oxidative stress biomarkers across all organs. However, it is essential to note that our star plots illustrate a tendency for CBPF to activate antioxidant enzymes and for MPs to produce oxidative damage. Regarding gene expression, our findings indicate that MPs led to an up-regulation in the expression of genes associated with apoptotic response (p53, casp3, cas9, bax, and bcl2) in all fish organs. Meanwhile, CBPF produced the same effect in genes related to antioxidant response (nrf1 and nrf2). Overall, our histological observations substantiated these effects, revealing the presence of plastic particles and tissue alterations in the gills and gastrointestinal tract of fish subjected to MPs. From these results, it can be concluded that CBPF does not represent a risk to fish after long exposure.

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Amphibians are very sensitive to many environmental changes, so these animals are considered good bioindicator models for ecotoxicology. Given the importance of the amphibian spleen for hematopoietic and immune responses, this can be a key organ for the evaluation of biomarkers to monitor the health of individuals in nature or in captivity. In this systematic review, we searched databases and summarized the main findings concerning the amphibian spleen as a source of possible biomarkers applied in different scientific fields. The searches resulted in 83 articles published from 1923 to 2022, which applied the use of splenic samples to evaluate the effects of distinct stressors on amphibians. Articles were distributed in more than twenty countries, with USA, Europe, and Brazil, standing out among them. Publications focused mainly on anatomical and histomorphological characterization of the spleen, its physiology, and development. Recently, the use of splenic biomarkers in pathology and ecotoxicology began to grow but many gaps still need to be addressed in herpetological research. About 85 % of the splenic biomarkers showed responses to various stressors, which indicates that the spleen can provide numerous biomarkers to be used in many study fields. The limited amount of information on morphological description and splenic anatomy in amphibians may be a contributing factor to the underestimated use of splenic biomarkers in herpetological research around the world. We hope that this unprecedented review can instigate researchers to refine herpetological experimentation, using the spleen as a versatile and alternative source for biomarkers in ecotoxicology.

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Bacillus toyonensis SFC 500-1E is a member of the consortium SFC 500-1 able to remove Cr(VI) and simultaneously tolerate high phenol concentrations. In order to elucidate mechanisms utilized by this strain during the bioremediation process, the differential expression pattern of proteins was analyzed when it grew with or without Cr(VI) (10 mg/L) and Cr(VI) + phenol (10 and 300 mg/L), through two complementary proteomic approaches: gel-based (Gel-LC) and gel-free (shotgun) nanoUHPLC-ESI-MS/MS. A total of 400 differentially expressed proteins were identified, out of which 152 proteins were down-regulated under Cr(VI) and 205 up-regulated in the presence of Cr(VI) + phenol, suggesting the extra effort made by the strain to adapt itself and keep growing when phenol was also added. The major metabolic pathways affected include carbohydrate and energetic metabolism, followed by lipid and amino acid metabolism. Particularly interesting were also ABC transporters and the iron-siderophore transporter as well as transcriptional regulators that can bind metals. Stress-associated global response involving the expression of thioredoxins, SOS response, and chaperones appears to be crucial for the survival of this strain under treatment with both contaminants. This research not only provided a deeper understanding of B. toyonensis SFC 500-1E metabolic role in Cr(VI) and phenol bioremediation process but also allowed us to complete an overview of the consortium SFC 500-1 behavior. This may contribute to an improvement in its use as a bioremediation strategy and also provides a baseline for further research.

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Envenomation by venomous fish, although not always fatal, is capable of causing damage to homeostasis by activating the inflammatory process, with the formation of edema, excruciating pain, necrosis that is difficult to heal, as well as hemodynamic and cardiorespiratory changes. Despite the wide variety of pharmacological treatments used to manage acute symptoms, none are effective in controlling envenomation. Knowing the essential role of neutralizing polyclonal antibodies in the treatment of envenoming for other species, such as snakes, this work aimed to produce a polyclonal antiserum in mice and test its ability to neutralize the main toxic effects induced by the venoms of the main venomous Brazilian fish. We found that the antiserum recognizes the main toxins present in the different venoms of Thalassophryne nattereri, Scorpaena plumieri, Potamotrygon gr. Orbignyi, and Cathorops spixii and was effective in pre-incubation trials. In an independent test, the antiserum applied immediately to the topical application of T. nattereri, P. gr orbygnyi, and C. spixii venoms completely abolished the toxic effects on the microcirculation, preventing alterations such as arteriolar contraction, slowing of blood flow in postcapillary venules, venular stasis, myofibrillar hypercontraction, and increased leukocyte rolling and adherence. The edematogenic and nociceptive activities induced by these venoms were also neutralized by the immediate application of the antiserum. Importantly, the antiserum prevented the acute inflammatory response in the lungs induced by the S. plumieri venom. The success of antiserum containing neutralizing polyclonal antibodies in controlling the toxic effects induced by different venoms offers a new strategy for the treatment of fish envenomation in Brazil.

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Due to their selective toxicity to insects, nicotinoid compounds have been widely used to control pests in crops and livestock around the world. However, despite the advantages presented, much has been discussed about their harmful effects on exposed organisms, either directly or indirectly, with regards to endocrine disruption. This study aimed to evaluate the lethal and sublethal effects of imidacloprid (IMD) and abamectin (ABA) formulations, separately and combined, on zebrafish (Danio rerio) embryos at different developmental stages. For this, Fish Embryo Toxicity (FET) tests were carried out, exposing two hours post-fertilization (hpf) zebrafish to 96 hours of treatments with five different concentrations of abamectin (0.5-11.7 mg L-1), imidacloprid (0.0001-1.0 mg L-1), and imidacloprid/abamectin mixtures (LC50/2 - LC50/1000). The results showed that IMD and ABA caused toxic effects in zebrafish embryos. Significant effects were observed regarding egg coagulation, pericardial edema, and lack of larvae hatching. However, unlike ABA, the IMD dose-response curve for mortality had a bell curve display, where medium doses caused more mortality than higher and lower doses. These data demonstrate the toxic influence of sublethal IMD and ABA concentrations on zebrafish, suggesting that these compounds should be listed for river and reservoir water-quality monitoring.

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The increasing use of Rare Earth Elements (REE) in emerging technologies, medicine and agriculture has led to chronic aquatic compartment contamination. In this context, this aimed to evaluate the acute toxic effects of lanthanum (La), neodymium (Nd) and samarium (Sm), as both single and binary and ternary mixtures on the survival of the microcrustacean Daphnia similis. A metal solution medium with (MS) and without EDTA and cyanocobalamin (MSq) as chelators was employed as the assay dilution water to assess REE bioavailability effects. In the single exposure experiments, toxicity in the MS medium decreased following the order La > Sm > Nd, while the opposite was noted for the MSq medium, which was also more toxic than the MS medium. The highest MS toxicity was observed for the binary Nd + La (1:1) mixture (EC50 48 h of 11.57 ± 1.22 mg.L-1) and the lowest, in the ternary Sm + La + Nd (2:2:1) mixture (EC50 48 h 41.48 ± 1.40 mg.L-1). The highest toxicity in the MSq medium was observed in the single assays and in the binary Sm + Nd (1:1) mixture (EC50 48 h 10.60 ± 1.57 mg.L-1), and the lowest, in the ternary Sm + La + Nd (1:2:2) mixture (EC50 48 h 36.76 ± 1.54 mg.L-1). Concerning the MS medium, 75 % of interactions were additive, 19 % antagonistic, and 6 % synergistic. In the MSq medium, 56 % of interactions were synergistic and 44 % additive. The higher toxicity observed in the MSq medium indicates that the absence of chelators can increase the concentrations of more toxic free ions, suggesting that the MS medium should be avoided in REE assays. Additive interactions were observed in greater or equivalent amounts in both media and were independent of elemental mixture ratios. These findings improve the understanding of environmental REE effects, contributing to the establishment of future guidelines and ecological risk calculations.

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Envenomation by venomous fish, although not always fatal, is capable of causing damage to homeostasis by activating the inflammatory process, with the formation of edema, excruciating pain, necrosis that is difficult to heal, as well as hemodynamic and cardiorespiratory changes. Despite the wide variety of pharmacological treatments used to manage acute symptoms, none are effective in controlling envenomation. Knowing the essential role of neutralizing polyclonal antibodies in the treatment of envenoming for other species, such as snakes, this work aimed to produce a polyclonal antiserum in mice and test its ability to neutralize the main toxic effects induced by the venoms of the main venomous Brazilian fish. We found that the antiserum recognizes the main toxins present in the different venoms of Thalassophryne nattereri, Scorpaena plumieri, Potamotrygon gr. Orbignyi, and Cathorops spixii and was effective in pre-incubation trials. In an independent test, the antiserum applied immediately to the topical application of T. nattereri, P. gr orbygnyi, and C. spixii venoms completely abolished the toxic effects on the microcirculation, preventing alterations such as arteriolar contraction, slowing of blood flow in postcapillary venules, venular stasis, myofibrillar hypercontraction, and increased leukocyte rolling and adherence. The edematogenic and nociceptive activities induced by these venoms were also neutralized by the immediate application of the antiserum. Importantly, the antiserum prevented the acute inflammatory response in the lungs induced by the S. plumieri venom. The success of antiserum containing neutralizing polyclonal antibodies in controlling the toxic effects induced by different venoms offers a new strategy for the treatment of fish envenomation in Brazil.

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Every year, Brazil intensifies its activity in agriculture and, as a result, it has become one of the biggest consumers of pesticides in the world. The high rate of these substances raises environmental and human health concerns. Therefore, we collected papers from PubMed, Scopus, Scielo, and Web of Science databases, from 2015 to 2021. After a blind selection using the software Rayyan QCRI by two authors, 51 studies were included. Researchers from the South and the Southeast Brazilian regions contributed to most publications, from areas that concentrate agricultural commodity complexes. Among the pesticides described in the studies, insecticides, herbicides, and fungicides were the most frequent. The articles reported multiple toxic effects, particularly in rural workers. The results obtained can be used to direct policies to reduce the use of pesticides, and to protect the health of the population.

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Every year, Brazil intensifies its activity in agriculture and, as a result, it has become one of the biggest consumers of pesticides in the world. The high rate of these substances raises environmental and human health concerns. Therefore, we collected papers from PubMed, Scopus, Scielo, and Web of Science databases, from 2015 to 2021. After a blind selection using the software Rayyan QCRI by two authors, 51 studies were included. Researchers from the South and the Southeast Brazilian regions contributed to most publications, from areas that concentrate agricultural commodity complexes. Among the pesticides described in the studies, insecticides, herbicides, and fungicides were the most frequent. The articles reported multiple toxic effects, particularly in rural workers. The results obtained can be used to direct policies to reduce the use of pesticides, and to protect the health of the population.

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Arsenic (As) causes health effects, especially cancer. Rice (Oryza sativa L.) can contain high As concentrations. Using ICP-MS, we quantified the total As (tAs) levels in the main brands of rice (n = 103) and infant cereals (n = 27) consumed by Brazilians. The levels were compared to the maximum limits prescribed by regulatory agencies. We estimated the daily intake (EDI) of As by Brazilians by combining the mean As concentration determined in the white rice samples with per capita daily consumption divided by the average body weight as reported by the Brazilian Institute of Geography and Statistics in 2010. The possible health risk for consumers was assessed by calculating the margin of exposure (MOE) as prescribed by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Moreover, tAs was determined in 11 pesticides used by Brazilian farmers. The tAs levels in the rice ranged from 0.003 to 1.3 mg kg-1. Approximately 27% of the white rice contained tAs levels above the limit set by Mercosul (0.3 mg kg-1) and 45% were above the limit set by the European Commission (0.2 mg kg-1). In the infant cereals, tAs levels ranged from 0.003 to 0.243 mg kg-1. In the pesticides, tAs levels ranged from 0.005 to 0.315 mg L-1. The EDI showed that, on average, Brazilians consume 4.13 µg As kg-1 BW weekly. In addition, a low MOE was observed, demonstrating that high use of rice presents a risk of high inorganic (iAs) exposure, which represents a public health concern.

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Astrocytes can protect neurons against oxidative stress and excitability-dependent disorders, such as epilepsy. Valeriana officinalis has been used as anticonvulsant and can exert an antioxidant effect, which may underlie its opposing action against the toxic effects of the pesticide rotenone. We investigated the V. officinalis /rotenone interaction in the cortical spreading depression (CSD), a phenomenon that depends upon brain excitability (in vivo model). In addition, we analyzed the protective action of V. officinalis against the cytotoxic effects of rotenone in cultures of rat C6 glioma cells (in vitro model). For the CSD study, Wistar rats received either V. officinalis (250 mg/kg/day via gavage for 15 days; n = 8) or 10 mg/kg/day rotenone via subcutaneous injections for 7 days (n = 7), or they received both substances (n = 5). Two control groups received either saline (vehicle for V. officinalis; n = 8) or 1% Tween-80 aqueous solution (vehicle for rotenone; n = 9). After treatment, CSD was recorded for 4 h. The rotenone- and V. officinalis-treated groups presented, respectively, with lower (2.96 ± 0.14 mm/min), and higher CSD propagation velocity (3.81 ± 0.10 mm/min) when compared with the controls (Tween-80, 3.37 ± 0.06 mm/min and saline, 3.35 ± 0.08 mm/min; p < 0.05). The rotenone plus V. officinalis-treated group displayed a CSD velocity (3.38 ± 0.07 mm/min) that was similar to controls. In line with these results, in vitro experiments on rat glioma C6 cells revealed a protective effect (MTT assay) of V. officinalis against rotenone-induced cytotoxicity. These results suggest the therapeutic potential of V. officinalis for treating neurological diseases involving redox imbalance and astrocyte dysfunction.

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The effect of tetracyclines used for swine food-production (tetracycline and oxytetracycline) on enriched nitrifying bacteria cultures over time was investigated in this study. Short-term exposure assays were performed in different concentrations of each antibiotic, using ammonia oxidizing bacteria (AOB) culture and nitrifying bacteria. The results pointed out a higher inhibitory effect of tetracycline on both bacterial communities. The AOB was more sensitive to antibiotic exposure when compared to the nitrifying culture. Although high antibiotic concentrations were applied, the half maximal inhibitory concentration (IC50) was achieved only for the AOB culture exposed to tetracycline at a concentration of 273 mg L-1. Nonetheless, the long-term exposure assay demonstrated a reduction of the tetracycline inhibition effect against AOB. The exposure to 100 mg L-1 of tetracycline (TC) did not show relevant influence over ammonium conversion efficiency; however, at 128 mg L-1 of TC, the efficiency decreased from 94% to 72%. Further investigation revealed that TC reduced the final effluent quality due to the development of a resistance mechanism by AOB culture against this antibiotic. This mechanism involves increasing the excretion of extracellular polymeric substances (EPS) and soluble microbial products (SMP), which probably increases BOD, and reduces ammonia consumption by the bacterial culture.

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The present study was conducted to investigate the ability of Saccharomyces cerevisiae RC016 (Sc)-based feed additive to reduce liver toxicity, residual aflatoxin B1 (AFB1) levels and influence intestinal structure in broiler chickens fed chronic aflatoxin B1-contaminated diets. A total of 100 one-day-old male commercial line (Ross) broiler chickens were divided into 4 treatments, with 5 pens per treatment and 5 broiler chickens per pen. Birds were randomly assigned to 4 treatments, which were namely treatment 1 (T1), control diet (CD); T2, CD + Sc at 1 g/kg; T3, CD + AFB1 at 100 µg/kg; T4, CD + Sc at 1 g/kg + AFB1 at 100 µg/kg. The liver histopathology of broiler chickens fed diets with AFB1 showed diffused microvacuolar fatty degeneration. The addition of Sc showed normal hepatocytes similar to the control. The small intestine villi from AFB1 group showed atrophy, hyperplasia of goblet cells, prominent inflammatory infiltrate and oedema. In contrast, the small intestine villi from birds that received the yeast plus AFB1 showed an absence of inflammatory infiltrate, and atrophy; moreover, a lower number of goblet cells compared to the groups with AFB1 was observed. The morphometric intestine studies showed that a significant decrease (P < 0.05) in the crypt depth values when Sc was applied to AFB1-contaminated diets. Although the intestinal villus height and apparent adsorption area did not show significant differences (P > 0.05), there was a tendency to improve these parameters. The residual levels of AFB1 in livers were significantly reduced (P < 0.05) in the presence of the yeast. The present work demonstrated that the addition of Sc alone or in combination with AFB1 in the broiler chicken diets had a beneficial effect in counteracting the toxic effects of AFB1 in livers besides improving the histomorphometric parameters and modulating the toxic effect of AFB1 in the intestine.

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The aim of the present study was to characterize the effects of particles on metal aquatic toxicity in a tropical system. To this end, we investigated the effects of natural suspended solids on copper (Cu) geochemistry and acute toxicity to the cardinal tetra (Paracheirodon axelrodi), in 2 Amazonian rivers with different total suspended solids (TSS) levels: the Rio Negro (low TSS ~ 8 mg L-1 ) and the Rio Solimões (high TSS ~ 70 mg L-1 ). The effect of particles on Cu aqueous geochemistry was assessed by measuring total, dissolved, and free ionic Cu concentrations in filtered (<0.45 µm) and unfiltered waters. Furthermore, acute Cu toxicity to fish was assessed in both filtered and unfiltered waters, by measuring physiological net fluxes of Na+ , Cl- , K+ , and total ammonia (in both river waters) and 96-h fish mortality (in Rio Solimões only). The particles in the Rio Negro were not abundant enough to play a significant role in our study. On the other hand, the Rio Solimões particles bound approximately 70% of total aqueous Cu in our tests. In agreement with bioavailability-based models, this decrease in dissolved (and free ionic) Cu concentration decreased Cu lethality in the 96-h toxicity tests. In the physiological measurements, the best evidence of particle protection was the total alleviation of Cu-induced Cl- losses. These flux tests also suggested that the particles themselves may negatively affect Na+ balance in the fish. Overall, the present study supports the use of bioavailability concepts to account for the role of natural suspended solids on metal biological effects in the Amazon River basin. Environ Toxicol Chem 2019;38:2708-2718. © 2019 SETAC.

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Insect venom phospholipases have been identified in nearly all clinically relevant social Hymenoptera, including bees, wasps and ants. Among other biological roles, during the envenoming process these enzymes cause the disruption of cellular membranes and induce hypersensitive reactions, including life threatening anaphylaxis. While phospholipase A2 (PLA2) is a predominant component of bee venoms, phospholipase A1 (PLA1) is highly abundant in wasps and ants. The pronounced prevalence of IgE-mediated reactivity to these allergens in sensitized patients emphasizes their important role as major elicitors of Hymenoptera venom allergy (HVA). PLA1 and -A2 represent valuable marker allergens for differentiation of genuine sensitizations to bee and/or wasp venoms from cross-reactivity. Moreover, in massive attacks, insect venom phospholipases often cause several pathologies that can lead to fatalities. This review summarizes the available data related to structure, model of enzymatic activity and pathophysiological roles during envenoming process of insect venom phospholipases A1 and -A2.

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Trypanosoma evansi is a zoonotic parasite associated with high animal mortality that has gained importance due to its capacity to infect humans. Recently, some evidences have demonstrated that T. evansi infection causes severe genotoxic and cytotoxic damage in brain cells, contributing to the pathogenesis and clinical signs of the disease. In this sense, the aim of this study was to evaluate whether nerolidol-loaded in nanospheres, a natural compound with trypanocidal and neuroprotective effects, is able to protect the brain tissue from the cytotoxic and genotoxic effects found during T. evansi infections. Trypanosoma evansi induced brain genotoxic effects through increased damage index (DI) and frequency of damage (FD) when compared to the control group. Moreover, T. evansi induced cytotoxic effects through the reduction of brain cell viability compared to the control group. The metabolites of nitric oxide (NO x ) increased in infected animals compared to the control group. The treatment with nerolidol-loaded in nanospheres prevented the increase on brain DI, FD, and NO x levels, as well as the reduction on cell viability. Based on these evidences, these results confirm that T. evansi induces genotoxic and cytotoxic damage mediated by the upregulation of NO x levels. The most important finding is that nerolidol-loaded in nanospheres was able to prevent DNA damage and cell mortality through the modulation of brain NO x levels. In summary, this treatment can be considered an interesting approach to prevent T. evansi brain damage due its anti-inflammatory property.

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The improvement of in vitro embryo production by culture media supplementation has been a potential tool to increase blastocyst quality and development. Recently, lipid-core nanocapsules (LNC), which were developed for biomedical applications as a drug-delivery system, have demonstrated beneficial effects on in vitro embryo production studies. LNCs have a core composed of sorbitan monostearate dispersed in capric/caprylic triglyceride. Based on that, we firstly investigated if LNCs supplemented during in vitro oocyte maturation had affinity to the mineral oil placed over the top of the IVM media. Also, the effects of LNC supplementation in different concentrations (0; 0.94; 4.71; 23.56; 117.80 and 589.00µg/mL) during the in vitro maturation protocol were evaluated in oocytes and blastocysts by in vitro tests. LNCs seemed not to migrate to the mineral oil overlay during the in vitro oocyte maturation. Interestingly, LNCs did not show toxic effects in the oocyte in vitro maturation rate, cumulus cells expansion and oocyte viability. The highest LNCs concentration tested (589µg/mL) generated the lowest ROS and GSH levels, and reduced apoptosis rate when compared to the control. Additionally, toxic effects in embryo development and quality were not observed. The LNC supramolecular structure demonstrated to be a promising nanocarrier to deliver molecules in oocytes and embryos, aiming the improvement of the embryo in vitro development.

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Cyanobacteria produce different toxic compounds that affect animal life, among them hepatotoxins and neurotoxins. Because cyanobacteria are able to produce a variety of toxic compounds at the same time, organisms may be, generally, subjected to their combined action. In the present study, we demonstrate the single and combined effects on cladocerans of cyanobacteria that produce microcystins (hepatotoxins) and saxitoxins (neurotoxins). Animals were exposed (either singly or combined) to 2 strains of cyanobacteria isolated from the same environment (Funil Reservoir, Rio de Janeiro, Brazil). The effects on clearance rate, mobility, survivorship, fecundity, population increase rate (r), and the antioxidant enzymes glutathione-S-transferase (GST) and catalase (CAT) were measured. Cladoceran species showed a variety of responses to cyanobacterial exposures, going from no effect to impairment of swimming movement, lower survivorship, fecundity, and general fitness (r). Animals ingested cyanobacteria in all treatments, although at lower rates than good food (green algae). Antioxidant defense responses were in accordance with fitness responses, suggesting that oxidative stress may be related to such effects. The present study emphasizes the need for testing combined actions of different classes of toxins, because this is often, and most likely, the scenario in a more eutrophic world with global climatic changes. Environ Toxicol Chem 2017;36:2689-2697. © 2017 SETAC.

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