Micronuclei and other erythrocyte nuclear abnormalities in fishes from the Great Lakes Basin, USA

Assessment of sub-lethal effects of Celcron on Java barb through erythrocyte morphology and acetylcholinesterase activity: Implications for environmental health in aquatic ecosystems

Industrialization and the extensive use of chemicals have raised significant concerns about their environmental impacts, particularly on aquatic ecosystems. This study evaluated the sub-lethal effects of Celcron (Cec), an organophosphate insecticide, on the Java barb (Barbonymus gonionotus) through erythrocyte morphology and acetylcholinesterase (AChE) activity, aiming to refine biomarkers for environmental health assessments. We hypothesized that sub-lethal Cec exposure would induce significant erythrocyte abnormalities and decrease AChE activity in Java barb, with variable recovery rates between gill and kidney tissues. To test this, we exposed the juvenile Java barbs to two sub-lethal Cec concentrations - 0.01 ppm (10 % of the LC50) and 0.05 ppm (50 % of the LC50) -for 60 days. After the exposure period, the fish were placed in pesticide-free water to allow for recovery. Results indicated a significant decline in AChE activity in both liver and kidney tissues, with activity levels showing gradual recovery over time. Erythrocyte abnormalities, including nuclear and cellular changes, were significantly elevated in response to Cec exposure. The frequency of nuclear abnormalities such as micronuclei and binucleation increased in a concentration- and duration-dependent manner, with the gill blood exhibiting higher sensitivity and slower recovery compared to kidney blood. Cellular abnormalities such as twin, teardrop and spindle-shaped cells were also more prevalent in Cec-treated fish. Recovery from these abnormalities was observed but varied between gill and kidney blood, with gill blood showing higher sensitivity and slower recovery compared to kidney blood. This study underscores the utility of AChE activity and erythrocyte abnormalities as biomarkers for assessing pesticide impacts on aquatic organisms. The findings highlight the sensitivity of fish erythrocytes to environmental contaminants and emphasize the need for continued research to better understand the long-term effects of pesticide exposure on aquatic health and ecosystem stability.

Effects of acetaminophen exposure on behavior and erythrocyte nuclear morphology of juvenile Oreochromis niloticus

The occurrence of pharmaceuticals in the environment can have undesirable effects on nontarget animals, including fish. The present experiment assessed the effects of subchronic exposure to waterborne acetaminophen (N-acetyl-p-aminophenol) (APAP) on selected behavioral aspects (physical avoidance response, ventilation rate, and food detection rate) and erythrocyte nuclear abnormality (ENA) in juvenile Oreochromis niloticus. Two groups of fish were exposed to APAP dissolved in aged municipal water (T1: 2 mg/L and T2: 10 mg/L) for 8 weeks in three replicates (n = 7 fish per tank), alongside a control group (C) without APAP. APAP-exposed fish spent significantly (p < .05) longer time to detect food (T1: 32.6 ± 4.55 s and T2: 39.6 ± 4.66 s) compared to the control group (19.9 ± 2.46 s). Both APAP-exposed groups exhibited attenuated physical avoidance responses (76.7%, 68.7%, and 87.3% in T1, T2, and C, respectively) and a lower mean ventilation rate compared to the control group (194.5 ± 15.5, 179.1 ± 11.6, and 233.2 ± 19.0 per min in T1, T2, and C, respectively). The frequency occurrence of ENA types such as bi-nucleated, notched nuclei, lobed nuclei, and blebbed nuclei (except micronuclei) was significantly higher (p < .05) in APAP-exposed groups compared to the control, with more pronounced effects in the T2 group. The study concludes that APAP exposure prompts significant alterations in behavior and erythrocyte nuclear morphology, emphasizing the value of monitoring and regulating the entry of pharmaceuticals, including APAP, into aquatic environments to prevent unintended effects on non-target organisms like Oreochromis niloticus.

Cytome analysis (micronuclei and nuclear anomalies) in bioindication of environmental pollution in animals with nuclear erythrocytes

Assessment of cytogenetic homeostasis of indicator animals is of great importance in ecological monitoring. The simplest method of its study is micronucleus analysis. Animals with nuclear erythrocytes are often used as indicator animals. In addition to the micronuclei usually recorded, a wide range of cytological nuclear and cellular abnormalities (cytomic analysis) is encountered when assessing the spontaneous level and under the influence of anthropogenic factors. Spontaneous frequency of cytogenetic disorders in 36 species of fish, amphibians, reptiles and birds was studied. Ecological monitoring of territories of Kazakhstan with different types of pollution (radiation, petrochemical, pesticide, heavy metals, due to rocket and space activities) was carried out with the help of separate species of animals. The results of the study include comparative descriptions, schematics and microphotographs clearly demonstrating a wide range of cytological anomalies of nuclear erythrocytes of animals of different classes. The greatest spectrum of nuclear anomalies in the studied animals was registered at petrochemical and pesticide contamination of territories. Depending on the tasks and climatic-geographical conditions, all investigated species can be used as bioindicators. Testudo horsfieldii is an exception for desert regions due to high spontaneous micronuclei level in this species. A review of the names of the main nuclear anomalies is carried out and variants of its ordering are proposed.

A biomarker approach to study the effects of polluted Brazilian urban reservoirs in a native fish

Two of the largest water reservoirs in the Metropolitan Region of São Paulo, Brazil (MRSP), named Billings and Guarapiranga, are facing high levels of anthropic impact. This is evidenced by the presence of contaminants and pollutants, which are deteriorating their water quality. Therefore, this study evaluated antioxidant defense enzymes, lipoperoxidation and genotoxicity, in adult females of a native species, Astyanax altiparanae from the Guarapiranga and Billings reservoirs. The study also aimed to evaluate these biomarkers during two different periods of the year, the rainy (summer) and dry (winter) seasons. The oxidative stress was evaluated by the activity of enzymes such as glutathione peroxidase, glutathione S-transferases, superoxide dismutase, and catalase in the gills and liver, and the occurrence of lipoperoxidation was also evaluated in both organs. The genotoxicity was assessed by performing comet assay, micronucleus, and nuclear abnormality tests on blood samples. The results showed that fish from both reservoirs are subjected to oxidative stress and genotoxic damage, mainly during winter, but fish living in Billings showed greater alterations than fish from Guarapiranga. Likewise, the results of the principal component analysis suggested that caffeine, nitrogenous compounds, and some metals might be triggering these toxic effects in fish.

Study of the frequencies of erythrocyte abnormalities as in situ biomarkers of genotoxic risk of chemicals in special fish stock in water supply reservoirs

In three water-supply reservoirs in the catchment area of the Odra River (Czech Republic), a special fish stock was monitored for control of health to estimate the mutagenic effect of chemicals. The results contribute to obtaining initial information about the morphology of erythrocyte abnormalities classified in 21 categories in 16 fish species in reservoirs with abundant salmonids (the Morávka Reservoir) or with the prevalence of cyprinids (the Kružberk and Šance Reservoirs), not directly exposed to the adverse environmental effects such as industrial, urban, agricultural and intensive farming activities. The different intensities and prevalence of nuclear abnormalities (NA) and cytoplasmic abnormalities (CA) in fish from the same reservoir habitat show that to be able to obtain an objective view of the genotoxic risk of chemicals, it is necessary to respect the different requirements of the fish for the exploitation of the food available in the biotope and to subject all representatives of piscivorous, omnivorous and benthophagous fishes in the reservoir to cytogenetic analysis. The occurrence of certain categories of erythrocyte abnormalities in diseased fish draws attention to the need to know the state of health of the fish and to employ this knowledge to exclude parasitological, viral and other infectious agents. These results are the first report of the frequencies of erythrocyte abnormalities in native fish. They should serve to check which of the categories examined could be of use in assessing the genotoxic risk in other stagnant and running aquatic ecosystems affected by anthropogenic activities.

Hazard assessment of complex legacy-contaminated groundwater mixtures using a novel approach method in adult fathead minnows

Traditional risk assessment methods face challenges in the determination of drivers of toxicity for complex mixtures such as those present at legacy-contaminated sites. Bioassay-driven analysis across several levels of biological organization represents an approach to address these obstacles. This study aimed to apply a novel transcriptomics tool, the EcoToxChip, to characterize the effects of complex mixtures of contaminants in adult fathead minnows (FHMs) and to compare molecular response patterns to higher-level biological responses. Adult FHMs were exposed for 4 and 21 days to groundwater mixtures collected from a legacy-contaminated site. Adult FHM showed significant induction of micronuclei in erythrocytes, decrease in reproductive capacities, and some abnormal appearance of liver histology. Parallel EcoToxChip analyses showed a high proportion of upregulated genes and a few downregulated genes characteristic of compensatory responses. The three most enriched pathways included thyroid endocrine processes, transcription and translation cellular processes, and xenobiotics and reactive oxygen species metabolism. Several of the most differentially regulated genes involved in these biological pathways could be linked to the apical outcomes observed in FHMs. We concluded that molecular responses as determined by EcoToxChip analysis show promise for informing of apical outcomes and could support risk assessments of complex contaminated sites.

2,4-D-based herbicide underdoses cause mortality, malformations, and nuclear abnormalities in Physalaemus cuvieri tadpoles

Amphibians are considered bioindicators of the environment due to their high sensitivity and involvement in terrestrial and aquatic ecosystems. In the last two decades, 2,4-D has been one of the most widely used herbicides in Brazil and around the world, as its use has been authorized for genetically modified crops and therefore has been detected in surface and groundwater. Against this background, the aim of this work was to investigate the effects of environmentally relevant concentrations of 2,4-D-based herbicides on survival, malformations, swimming activity, presence of micronuclei and erythrocyte nuclear abnormalities in Physalaemus cuvieri tadpoles. The amphibians were exposed to six concentrations of 2,4-D-based herbicides: 0.0, 4.0, 30.0, 52.5, 75.0, and 100 μg L-1, for 168 h. At concentrations higher than 52.5 μg L-1, significantly increased mortality was observed from 24 h after exposure. At the highest concentration (100 μg L-1), the occurrence of mouth and intestinal malformations was also observed. The occurrence of erythrocyte nuclear abnormalities at concentrations of 30.0, 52.5, 75.0 and 100 μg L-1 and the presence of micronuclei at concentrations of 52.5, 75.0, and 100 μg L-1 were also recorded. These effects of 2,4-D in P. cuvieri indicate that the ecological risk observed at concentrations above 10.35 μg L-1 2,4-D may represent a threat to the health and survival of this species, i.e., exposure to 2,4-D at concentrations already detected in surface waters in the species' range is toxic to P. cuvieri.

Assessment of toxicity, genotoxicity and oxidative stress in Fejervarya limnocharis exposed to tributyltin

Tributyltin (TBT) is widely used in various commercial applications due to its biocidal properties. Toxicological and genotoxicological data on TBT exposure to amphibians is insufficient. Our study aimed to determine the acute toxicity and genotoxic potential of TBT in Fejervarya limnocharis tadpoles. Furthermore, oxidative stress was also investigated in TBT-treated tadpoles. Tadpoles of Gosner stage (26-30) were screened and subjected to increasing concentrations of TBT (0, 3, 7, 11, 15, 19, 23 µg/L) for determining the LC50 values for 24 h, 48 h, 72 h, and 96 h. LC50 values of TBT for 24 h, 48 h, 72 h, and 96 h were found to be 19.45, 15.07, 13.12, and 11.84 μg/L respectively. Based on the 96 h LC50 value (11.84 µg/L), tadpoles were exposed to different sub-lethal concentrations of TBT for the evaluation of its genotoxic potential and effects on oxidative balance. The role of TBT on survivability, growth, and time to metamorphosis was also assessed. TBT exposure significantly altered the life history traits measured, increased mortality, and delayed the time taken to metamorphosis. Results indicated significant induction of micronucleus (MN, p < 0.001) and other erythrocytic nuclear aberrations (ENA, p < 0.01) in the TBT-treated groups. Significant alterations in comet parameters and oxidative balance were also observed in the treated groups. The present study findings might add to the cause of the gradual population decline seen in the amphibians. This study also demonstrates the alteration of the life-history traits, oxidative balance, and DNA damage upon TBT exposure which can have long-term consequences for the anuran amphibian F. limnocharis.

Toxic, genotoxic, mutagenic, and bioaccumulative effects of metal mixture from settleable particulate matter on American bullfrog tadpoles (Lithobates catesbeianus)

Amphibians are more susceptible to environmental stressors than other vertebrates due to their semipermeable skin and physiological adaptations to living in very specific microhabitats. Therefore, the aim of the present study was to investigate the effects of a metal mixture from settleable particulate matter (SePM) released from metallurgical industries on Lithobates catesbeianus tadpoles. Endpoints analyzed included metal bioconcentration, morphological (biometrical indices), hematological parameters (hemoglobin and blood cell count), and erythrocyte DNA damage (genotoxicity and mutagenicity). American bullfrog tadpoles (Gosner's stage 25) were kept under control condition (no contaminant addition) or exposed to a sub-lethal and environmentally relevant concentration (1 g.L-1) of SePM for 96 h. Tadpoles exposed to SePM exhibited elevated whole blood levels of Fe56, AL, Sn, Pb, Zn, Cr, Cu, Ti, Rb, V, Ce, La, Ag, As. SePM-exposed tadpoles showed a significant decrease in condition factor (12%) and increases in hepatosomatic index (25%), hemoglobin concentration (17%), and total leukocytes (82%), thrombocytes (90%), and monocytes (78%) abundance. In addition, exposed tadpoles showed higher MN and ENAs (340 and 140%, respectively) frequencies, and erythrocyte DNA damage with approximately 1.2- to 1.8-fold increases in comet parameters. Taken together, these results suggest that the multimetal mixture found in SePM is potentially genotoxic and mutagenic to L. catesbeianus tadpoles, induces stress associated with hematological changes, and negatively affects growth. Although such contamination occurs at sublethal levels, regulatory standards are needed to control the emission of SePM and protect amphibian populations.

Evaluation of the Genotoxic and Histological Effects in Neotropical Fish Prochilodus Lacustris (Pisces, Prochilodontidae) in Conservation Area of the Brazilian Northeast

Human activities significantly impact the aquatic biota in lacustrine environments, leading to negative environmental consequences. Due to this, this study was carried out to evaluate the genotoxic and histological biomarkers in the gills and kidneys of Prochilodus lacustris. The collection of fish and water was conducted in three distinct stations (S1, S2, S3) in an international protected area in northeast Brazil. The histological alterations index was used to assess changes in the gills and kidneys at a histological level. In addition, micronucleus and nuclear abnormalities tests were employed to examine damage to the genetic material. According to the frequency of Micronucleus, nuclear injuries, and the histopathology of gills and kidneys, it can be inferred that station S1 had the highest impact on the fish, causing significant harm. Based on our findings, the organisms residing in Lake Açu are adversely affected by the poor environmental conditions. This raises doubts about the effectiveness of the Protection Area by Humid Zone of International Interest in Northeast Brazil.

Nuclear and morpho-histopathological alterations in Astyanax altiparanae exposed to effluent from the process of anodizing aluminum

Aluminum is a metal widely used from household utensils to civil construction. Anodizing aluminum is a procedure to form a thick layer of aluminum oxide on the surface in order to confer greater resistance to the material. This process generates an effluent with acidic pH and a high concentration of sulfate. Alternatives for the treatment of this effluent involve the use of the chemical precipitation technique, which can be used with salts of barium chloride (BaCl2), calcium chloride (CaCl2), and aluminum hydroxide with commercial limestone (Cc/Al (OH)3). The objective of this study was to evaluate the toxicity of effluents on Astyanax altiparanae (Lambari), by means of somatic, genetic, morphological, and histological markers after 24 and 96 h of exposure. After measuring the biometric data of the animals and the weight of the liver, we found that the condition factor (K) of individuals exposed to the effluent CaCl2 showed a slight reduction in growth after 96 h while the hepatosomatic index (HSI) remained unchanged for all effluents in both sampling times. The micronucleus test with erythrocytes indicated that the raw effluent (E2) induced nuclear changes after 24 h; however, this effect did not persist after 96 h of exposure. Branchial arches were collected and according to Bernet's index for histopathology, all effluents except Cc/Al (OH)3, induced significant changes in the gills. In accordance with the index of Poleksic and Mitrovic-Tutundzic, CaCl2 was the only effluent to compromise branchial operation. The branchial morphology investigated by SEM showed that the raw effluent (E1) induced injuries and compromised gill functions. This study reinforces the importance of biological tests for the assessment and validation of physical chemicals used and effluent treatment techniques as well as the development and application of biological parameters before the wastewater release, whether in a raw state or a treated one.

Exposure of adult zebrafish (Danio rerio) to SARS-CoV-2 at predicted environmentally relevant concentrations: Outspreading warns about ecotoxicological risks to freshwater fish

While the multifaceted social, economic, and public health impacts associated with the COVID-19 pandemic are known, little is known about its effects on non-target aquatic ecosystems and organisms. Thus, we aimed to evaluate the potential ecotoxicity of SARS-CoV-2 lysate protein (SARS.CoV2/SP02.2020.HIAE.Br) in adult zebrafish (Danio rerio) at predicted environmentally relevant concentrations (0.742 and 2.226 pg/L), by 30 days. Although our data did not show locomotor alterations or anxiety-like or/and anxiolytic-like behavior, we noticed that exposure to SARS-CoV-2 negatively affected habituation memory and social aggregation of animals in response to a potential aquatic predator (Geophagus brasiliensis). An increased frequency of erythrocyte nuclear abnormalities was also observed in animals exposed to SARS-CoV-2. Furthermore, our data suggest that such changes were associated with a redox imbalance [↑ROS (reactive oxygen species), ↑H2O2 (hydrogen peroxide), ↓SOD (superoxide dismutase), and ↓CAT (catalase)], cholinesterasic effect [↑AChE (acetylcholinesterase) activity], as well as the induction of an inflammatory immune response [↑NO (nitric oxide), ↑IFN-γ (interferon-gamma), and ↓IL-10 (interleukin-10)]. For some biomarkers, we noticed that the response of the animals to the treatments was not concentration-dependent. However, principal component analysis (PCA) and the "Integrated Biomarker Response" index (IBRv2) indicated a more prominent ecotoxicity of SARS-CoV-2 at 2.226 pg/L. Therefore, our study advances knowledge about the ecotoxicological potential of SARS-CoV-2 and reinforces the presumption that the COVID-19 pandemic has negative implications beyond its economic, social, and public health impacts.

Long-term exposure of zebrafish juveniles to carbon nanofibers at predicted environmentally relevant concentrations: Outspreading warns about ecotoxicological risks to freshwater fish

Although carbon-based nanomaterials (CNMs) toxicity has already been demonstrated in some animal models, little is known about the impact of carbon nanofibers (CNFs) on aquatic vertebrates. Thus, we aimed to evaluate the possible effects of long-term exposure of zebrafish (Danio rerio) juveniles (90 days) to CNFs in predicted environmentally relevant concentrations (10 ng/L and 10 μg/L). Our data revealed that exposure to CNFs did not affect the growth and development of the animals, in addition to not having induced locomotor alterations or anxiety-like behavior. On the other hand, we observed that zebrafish exposed to CNFs showed a response deficit to the vibratory stimulus test, alteration in the density of neuromasts recorded in the final ventral region, as well as an increase in thiobarbituric acid reactive substances levels and a reduction in total antioxidant activity, nitric oxide, and acetylcholinesterase activity in the brain. Such data were directly associated with a higher concentration of total organic carbon in the brain, which suggests the bioaccumulation of CNFs. Furthermore, exposure to CNFs induced a picture suggestive of genomic instability, inferred by the increased frequency of nuclear abnormalities and DNA damage in circulating erythrocytes. Although the individual analyses of the biomarkers did not point to a concentration-dependent effect, the principal component analysis (PCA) and the Integrated Biomarker Response Index (IBRv2) indicate a more prominent effect induced by the higher CNFs concentration (10 μg/L). Therefore, our study confirms the impact of CNFs in the studied model (D. rerio) and sheds light on the ecotoxicological risks of these nanomaterials to freshwater fish. Based on the ecotoxicological screening provided by our study, new horizons are opened for investigations into the mechanisms of action of CNFs, which will help understand the magnitude of the impact of these materials on aquatic biota.

Fabrication of hydroxyapatite-based nano-gold and nano-silver-doped bioceramic bone grafts: Enhanced mechanostructure, cell viability, and nuclear abnormality properties

In this study, nano-gold (nAu) and nano-silver (nAg) were doped at the molar ratios of Molar5-Molar30 to the Hydroxyapatite (HAp)-based bioceramic bone graft synthesized by the sol-gel method. The effects of nAu and nAg on structural, mechanical, cell viability, and nuclear abnormality of the synthesized bioceramic grafts were evaluated. The chemical and morphological properties of the bone grafts after production were examined through XRD and SEM-EDX analyses and mechanical tests. To determine the biocompatibility of the bone grafts, cell viability tests were performed using human fibroblast cells. In the cytotoxicity analyses, only HAp and HAp-nAu5 grafts did not show toxicological properties at any concentration, while HAp-nAg5 among the nAg-containing grafts gave the best results at the 200-100 μg/mL concentrations and showed significant cytotoxicity in human fibroblast cells. The other nAu-containing grafts showed toxicological properties in the concentration range of 200-50 μg/mL and nAg-containing grafts in the concentration range of 200-100 μg/mL against the negative control. The micronucleus (MN) analyses showed that the lowest total MN and L (lobbed) amounts, while the lowest total N (notched) amount, was obtained from the only HAp graft. It was found that the nAg-doped bone grafts gave higher total MN, L, and N amounts compared to the nAu-doped bone grafts. Furthermore, while the mean nuclear abnormality (NA) values of all grafts gave close results, the highest values were again obtained from the nAg-doped bone grafts.

Genotoxicity and cytotoxicity of textile production effluents, before and after Bacillus subitilis bioremediation, in Astyanax lacustris (Pisces, Characidae)

Textile effluents may be highly toxic and mutagenic. Monitoring studies are important for sustaining the aquatic ecosystems contaminated by these materials, which can cause damage to organisms and loss of biodiversity. We have evaluated the cyto- and genotoxicity of textile effluents on erythrocytes of Astyanax lacustris, before and after bioremediation by Bacillus subitilis treatment. We tested 60 fish (five treatment conditions, four fish per condition, in triplicate). Fish were exposed to contaminants for 7 days. The assays used were biomarker analysis, the micronucleus (MN) test, analysis of cellular morphological changes (CMC), and the comet assay. All concentrations of effluent tested, and the bioremediated effluent, showed damage significantly different from the controls. We conclude that water pollution assessment can be accomplished with these biomarkers. Biodegradation of the textile effluent was only partial, indicating the need for more thorough bioremediation to effect complete neutralization of toxicity.

Fish biomarker responses reflect landscape anthropic disturbance in savanna streams

Disturbance in the landscape surrounding streams can interfere with water quality and cause harm to aquatic organisms. In this study, we evaluate the influence of land use on the genetic and biochemical biomarkers of fish in streams of Brazilian savanna (Cerrado). We also evaluated whether biomarker responses are seasonally consistent. For this purpose, individuals of the Neotropical tetra fish Astyanax lacustris were exposed in cages for 96 h, in 13 streams draining agroecosystems with different degrees of disturbance during the dry and wet seasons. After exposure, blood, liver, and gills were collected for multibiomarker analyses (micronuclei, erythrocytic nuclear abnormalities, lipid peroxidation, antioxidant enzymes, and biotransformation enzyme). The results showed that the gradient of anthropic disturbance was positively associated with genotoxic damage (erythrocytic nuclear abnormalities) and negatively associated with antioxidant and biotransformation enzymes of the liver in both seasons. No association of the gradient of anthropic disturbance with the frequency of micronuclei and for most gill enzymes was found for both seasons. Landscape disturbance was also negatively associated with water quality in the wet season. These results indicate that changes in land use interfere with the genetic and biochemical processes of organisms. Thus, the multibiomarker approach may represent an effective strategy for assessing and monitoring terrestrial landscape disturbance.

Nanoplastics are bioaccumulated in fish liver and muscle and cause DNA damage after a chronic exposure

The extent of the widespread, planetary contamination by plastic waste is difficult to fully capture. Nanoplastics (NPs) are currently in the center of research concerning plastic litter, both for the analytical challenges they pose and for their potential to provoke hazardous effects in organisms. However, there are still many unanswered questions in this multidisciplinary field, with a crucial missing piece being the quantification of NPs in fish tissues after in vivo exposures. Another relevant question that is still greatly unexplored is how a chronic exposure to NPs will affect fish health. This study aims to provide answers to both of these relevant knowledge gaps. To this end, goldfish (Carassius auratus) were exposed to 44 nm polystyrene (PS)-NPs via water for 30 days. Following the exposure, gastrointestinal tract, liver and muscle were sampled for PS-NPs analysis by means of size exclusion chromatography coupled to high resolution mass spectrometry. PS-NPs were detected in all liver and muscle samples of exposed fish, with higher concentrations in liver than in muscle, whereas no PS-NPs were detected in the gastrointestinal tract. Nevertheless, exposure to PS-NPs did not induce changes in hematology parameters nor in cortisol and glucose levels in plasma. On the other hand, even a relatively low concentration of PS-NPs was able to cause DNA damage, measured by an increase in erythrocyte nuclear abnormalities, suggesting that PS-NPs can reach the cell nucleus and cause genotoxicity. These results show for the first time that PS-NPs find their way to fish muscle after chronic exposure, where they bioaccumulate, but do not alter fish survival nor hematological or physiological stress indicators. The accumulation of PS-NPs in fish muscle can represent a threat to human health as a possible route of exposure to small-sized plastics. The present results in a model fish species open windows for future studies in edible fish species.

Fish feed can show genotoxic damage

The present study was carried out to evaluate the genotoxic potential of nutritional quality of feed, using erythrocytic nuclear abnormalities assay in Nile tilapia and its correlation with available nutrients and common fish growth biomarkers. For this, ten feeds commercialized in Brazil were assessed on digestibility and performance assays with triplicate groups. Venipuncture of the caudal vein for abnormalities analyzed was performed 102 days after the fish were fed with the commercial feed twice a day, to apparent satiation. Nuclear abnormalities were analyzed in blood smears. Principal component analysis and correlation matrix were used to carry out an exploratory analysis of correlation between frequency of abnormalities and performance parameters or available nutrients. The frequency of abnormalities in erythrocytes of Nile tilapia, fish performance, and digestibility were feed-dependent. It was observed correlations between the frequency of most abnormalities and performance parameters or content of nutrients. The frequency of kidney-shaped (6.23 ± 4.14), bud nuclei (2.99 ± 1.95), bridge nuclei (0.53 ± 0.50), and binuclei (0.43 ± 0.59) was the highest in fish that also presented the worst performance among all treatments and correlated with digestible methionine. Micronucleus frequency (0.33 ± 0.49) was higher in fish from the same group that presented depressed feed intake and lower available zinc. Only one group presented vacuolated nuclei and the frequency of this abnormality was correlated with available phosphorus. The frequency of abnormalities in erythrocytes is a fish sensitive indicator of health and plays an important role as a complementary tool in the assessment of fish feeding. The variation in the frequency of nuclear abnormalities in erythrocytes obtained among fish fed with the different feeds allows the assertion that they contained genotoxic factors.

Neurotoxic, biotransformation, oxidative stress and genotoxic effects in Astyanax altiparanae (Teleostei, Characiformes) males exposed to environmentally relevant concentrations of diclofenac and/or caffeine

The present study evaluated neurotoxic, biotransformation, genotoxic and antioxidant responses to relevant environmental concentrations of diclofenac (0.4 μg L^-1) and caffeine (27.5 μg L^-1), separate and combined, in adult males of the freshwater fish Astyanax altiparanae after a subchronic exposure (14 days). Fish exposed to diclofenac and caffeine, both separate and combined, revealed a neurotoxic effect through the inhibition of acetylcholinesterase activity in the muscle, while diclofenac alone and in combination caused cyclooxygenase inhibition. Caffeine alone produces genotoxicity on this species but, when combined with diclofenac, it potentiates hepatic lipoperoxidation and the inhibition of oxidative stress enzymes, while diclofenac alone or in combination produces a general inhibition of important enzymes. This study suggests that aquatic contamination produced by these pharmaceuticals has the potential to affect homeostasis and locomotion in A. altiparanae and compromise their immune system and general health.

Mercuric chloride-induced oxidative stress, genotoxicity, haematological changes and histopathological alterations in fish Channa punctatus (Bloch, 1793)

The present study was undertaken to investigate the adverse effects of mercuric chloride (HgCl₂ ) overload in the fish Channa punctatus. Two sublethal test concentrations of HgCl₂ (1/20th and 1/10th of 96 h LC₅₀ i.e., 0.03 mg l^-1 (low concentration) and 0.07 mg l^-1 (high concentration), respectively, were used for exposure. Blood, liver and kidney tissues of the control and exposed specimens were sampled at intervals of 15, 30, and 45 days to assess alterations in oxidative stress, genotoxicity haematological parameters and histopathology. Significant changes in Hb%, RBC count, WBC count, antioxidant enzyme activity, i.e., superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione reductase (GR), were recorded. Micronuclei (MN) induction, nuclear abnormalities (NAs) and histopathological alterations were also observed in the exposed fish. Significant (P < 0.05) increase in the activities of SOD, CAT, GSH and GR was observed. After 45 days, a decrease in the level of GSH and GR was noticed which suggests an undermined anti-oxidative defence system in the fish exposed to HgCl₂ . Histological examination of the liver and kidney showed serious tissue injury and histological alterations. Significant increases in MN and NA frequencies reveal the DNA damage in erythrocytes of fish, and haematological changes show the toxicological potential of HgCl₂ . The observed changes in the antioxidant defence system, genotoxicity and haematological and histological changes in the present study provide the most extensive insight into HgCl₂ stress in C. punctatus.

Morphological analysis of erythrocytes of an Antarctic teleost under heat stress: Bias of the stabling effect

The stenothermal Antarctic fish that live in the coastal waters of the Terra Nova Bay (Ross Sea) are rarely exposed to temperatures above zero during the year. We tested whether a slight temperature rise of 1.5 °C affects a sensitive biomarker such as erythrocytes morphology in sections of blood pellets of a small demersal notothen. The erythrocytes' shape descriptors showed significant or highly significant differences temporally from the capture of fish to the conclusion of the experiment. Surprisingly, the erythrocyte's morphology did not show significant differences between the two experimental conditions, returning similar results in control fish stabled at -0.9 °C and in the fish treated at +0.6 °C, although the values of the shape descriptors were often lower in the latter. This study demonstrates the critical issues of comparative physiology in the study of extremely sensitive organisms, such as the fish of the High Antarctic Zone. Moreover, the stabling effect inside the aquarium facilities appears to significantly obscure the effects of the experimental heat treatment.

Effect of benzophenone-3 on the blood cells of zebrafish (Danio rerio)

Benzophenone-3 (BP-3) is a common component of organic sunscreen widely used that can affect especially aquatic ecosystems health, including fish. To verify the biological effects of low concentrations of BP-3 on blood cells, one hundred and forty zebrafish (D. rerio) were used and then randomly divided into five groups: control group (water), solvent group (alcoholic water), and BP-3 group (BP-3 at 7 µg L^-1, BP-3 at 70 µg L^-1, and BP-3 at 700 µg L^-1). The blood slices were stained with Panoptic stain and with Giemsa solution for the hematological analysis. During the exposure to BP-3, no behavioral changes were observed. Although no significant difference in total leukocytes occurred, an increase in neutrophils and a reduction of lymphocytes at the highest concentration on both 7th and 14th days were detected. The total and cytoplasmic area of erythrocytes on the 7th day at the highest concentration were reduced. In addition, alterations on the erythrocyte nuclear morphology in fish exposed to BP-3 were usually visualized, mainly when considered the occurrence of blebbed nucleus and micronucleus, indicating that BP-3 exhibits cytotoxic and mutagenic effects. The results indicate that BP-3 can interfere with the morphophysiology of aquatic organisms.

Giant Toads (Rhinella marina) From the Industrial Zones of Low Basin of the Coatzacoalcos River (Veracruz, MX) Presents Genotoxicity in Erythrocytes

The lower basin of Coatzacoalcos River is one of the most polluted regions of the southern Gulf of Mexico. Organochlorine compounds, polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons, and heavy metals have been registered in this region. In the present study, genotoxicity was evaluated in the blood of giant toads (Rhinella marina) from Coatzacoalcos' rural and industrial zones, and compared with laboratory toads. Determination of the frequency of micronucleus and erythrocyte nuclear abnormalities by the light microscope and cell cycle and apoptosis by flow cytometry were used as biomarkers of genotoxicity. We found more variability in micronucleus and more nuclear buds in toads from industrial zones. Also, cell cycle alterations and an increase of apoptosis in erythrocytes were found in toads from rural and industrial zones. Multivariate statistics show that the toads from the industrial zone were more affected than toads from laboratory and rural zones.

Physiological assessment of fish health in mineral-rich areas of Ganjam, Odisha, India, and chronic toxicity of zirconium oxychloride on the fishes of Channa punctata

The high concentration of metal toxicants in aquatic ecosystems has a detrimental impact on fish health that ultimately jeopardizes human health. Such threats mostly arise in mineral-rich areas where an increase in metal concentrations occurs in aquatic bodies due to anthropogenic activities like mining. The present study assessed the health of food fish Channa punctata from the mineral-rich areas of Ganjam, Odisha, India, mined for heavy and transition metal ores like ilmenite, zircon, monazite. The fishes collected from these areas showed histopathological anomalies in vital organs like the liver, kidney, gills, stomach and intestine while cytological analysis revealed vacuolated cytoplasm and micronuclei. Biochemical analysis showed a significantly lower lipid concentration in muscle (i.e., 0.177 ± 0.177 mg/gm) and liver (i.e., 0.169 ± 0.002 mg/gm) as compared to non-exposed fishes from adjoining non-mineral rich areas having a mean protein concentration of 87.48 ± 8.16 and 77.75 ± 0.892 mg/gm tissue in the muscle and liver, respectively, and a mean lipid concentration of 0.29 ± 0.009 mg/gm muscle and 0.34 ± 0.009 mg/gm liver. Chronic exposure to sublethal concentrations of zirconium oxychloride, a salt of zirconium, resulted in a significant decline in the concentration of protein, ranging from 57.5 ± 0.929 - 63.88 ± 1.95 mg/gm in muscle and 45.35 ± 2.332 - 51.98 ± 1.036 mg/gm in the liver. The lipid concentrations in muscle (0.03 ± 0.009 - 0.17 ± 0.009 mg/gm) and liver (0.06 ± 0.012 - 0.19 ± 0.007 mg/gm) were also significantly lower than the non-exposed fishes. Marked degenerative changes were identified in the histological sections of the gill, intestine, stomach, liver and kidney of zirconium oxychloride-treated fishes along with various nuclear deformities and micronucleus.

Exposure to a contaminated tropical freshwater (Awba Dam) in Ibadan, Nigeria, induced cytogenotoxicity and haemato-pathological changes in Clarias gariepinus

Awba reservoir serves the purpose of water supply in the University of Ibadan, Nigeria. Recent reports on pollution status have focused on toxicological implication of contaminants in this reservoir. But none is on genetic and systemic toxicity of the water in fish. We investigated cytogenotoxicity of Awba Dam water (ADW) on Clarias gariepinus using piscine micronucleus (MN) assay. Haematological and histopathological changes were also evaluated. Bi-monthly composite water samples were collected from the reservoir from July to October, 2018. The water was used to cultivate juvenile C. gariepinus in the laboratory for 1-4 months, and tap water was used as the negative control. Peripheral blood erythrocytes from the caudal veins of C. gariepinus were used for the monthly MN assessment. There was significant (p < 0.05) induction of MN and other erythrocyte nuclear abnormalities in C. gariepinus within the period of study. There were variations in the haematological indices and pathological alterations in sections of the gill, liver and kidney of C. gariepinus. The levels of some heavy metals in ADW were above standard permissible limits and might have contributed to the observed cytogenetic and systemic disruptions. These findings may be used by the concerned authorities to evolve management strategies for the reservoir's health and biologic resources.

Diclofenac and caffeine inhibit hepatic antioxidant enzymes in the freshwater fish Astyanax altiparanae (Teleostei: Characiformes)

Although concentrations of pharmaceutical compounds in aquatic ecosystems are low, they can cause toxic effects on organisms. The aim of this study was to evaluate the effects of diclofenac (DCF), a non-steroidal anti-inflammatory drug, and caffeine (CAF), a central nervous system stimulant, both alone or combined, in Astyanax altiparanae males under acute exposure (96 h), measuring neurotoxicity biomarkers, antioxidant response and damage at biochemical and cellular levels. DCF concentration in water, separated and combined, was 3.08 mg L^-1 and that of CAF was 9.59 mg L^-1. To assess neurotoxicity, brain and muscle acetylcholinesterase (AChE) activities were measured. To evaluate oxidative stress, the enzymatic activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione S-transferase (GST), as well as lipoperoxidation (LPO), were analyzed in liver and gills. Activity of hepatic cyclooxygenase (COX) was also evaluated. Genotoxicity was assessed in blood using comet assay and micronucleus test, as well as nuclear abnormalities. DCF and CAF, alone or combined, had neither effect on AChE activity, nor in the activity of SOD, CAT, GPx and GST in gills. In liver, DCF inhibited SOD and GPx activity, CAF inhibited CAT activity, the mixture inhibited SOD and GST activity; although only fish exposed to CAF showed increased hepatic LPO. Under these experimental conditions, no effect on COX activity was observed, nor cytotoxic and genotoxic damage. The most pronounced effects were caused by the drugs separately, since both compounds altered the enzymes, but only CAF triggered LPO, showing more harmful effects.

Micronuclei in Fish Erythrocytes as Genotoxic Biomarkers of Water Pollution: An Overview

Freshwater and marine water bodies receive chemical contaminants from industrial, agricultural, urban, and domestic wastes. Eco-genotoxicity assays are useful tools to assess the cumulative genotoxicity of these pollutants. Fish are suitable indicators for biomonitoring of mutagenic and carcinogenic pollution.In this review, we present a complete overview of the studies performed so far using the micronucleus test in peripheral erythrocytes of fish exposed to polluted water. We have listed all the species of fish used and the geographical distribution of the investigations. We have analyzed and discussed all technical aspects of using this test in fish, as well as the advantages and disadvantages of the different experimental protocols. We have reported the results of all studies. This assay has become, for years, one of the simplest, fastest, and most cost-effective for assessing genotoxic risk in aquatic environments. However, there are still several factors influencing the variability of the results. Therefore, we have given indications and suggestions to achieve a standardization of experimental procedures and ensure uniformity of future investigations.

Bioaccumulation of heavy metals and their toxicity assessment in Mystus species

This study was conducted on two native fish species namely Mystus vittatus and Mystus tengara inhabiting challenging environment of Yamuna River. The heavy metals concentrations in the river water were found to be as follows: Fe > Mn > Zn > Cu > Ni > Cr > Cd, all above the Bureau of Indian Standards (BIS) and World Health Organization (WHO) guidelines. The high metal pollution index in gill, liver, and kidney of M. vittatus was recorded compared to M. tengara. The pathology caused by the accumulation of heavy metals resulted significantly (p < 0.05) higher enzyme activities of alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and creatinine kinase (CK) in M. tengara as compared to M. vittatus. However, albumin: globulin ratio was found to be below 0.8 in both fishes. Higher total leukocyte (TLC) (48.5 × 10³/mm³), lymphocytes (40%), respiratory burst activity (1.9), and nitric oxide synthase (NOS) activity (13.11 U/L) in M. vittatus reflect high immune response. In addition, chromosomal breakage study showed significantly (p < 0.05) low micronuclei frequency, lobed nuclei, and kidney-shaped nuclei (KSN) in M. vittatus. These results indicate that under the same challenging conditions M. vittatus have more capability of resistance and its continuous survival points towards its suitability to serve as a bioindicator than M. tengara.

Toxicity and trophic transfer of polyethylene microplastics from Poecilia reticulata to Danio rerio

The potential transfer of microplastics (MPs) between vertebrates belonging to the same taxonomic group, and the impact of such a transfer on higher trophic levels remains little explored. An experimental food chain with two fish species was installed to test the hypothesis that polyethylene MPs (PE MPs) can accumulate in animals and cause behavioral, mutagenic and cytotoxic changes at upper trophic levels. Poecilia reticulata fry were exposed to MPs for 48 h and, subsequently, offered (as food) to Danio rerio adults for 10 days to simulate an upper level food chain. PE MPs quantification in fry and in different Danio rerio tissues evidenced their accumulation at the two assessed trophic levels. This finding suggested their absorption, adherence and translocation from one organism to another. The accumulation seen in D. rerio directly exposed to MPs was associated with behavioral disorders at upper trophic level. These animals presented behavior suggestive of anti-predatory response deficit when they were confronted with a potential aquatic predator (Geophagus brasiliensis). This finding was inferred through lower school cohesion, shallower school depth and shorter distance from the potential predator. In addition, animals exposed to MPs recorded higher nuclear abnormality rates and changes in the size and shape of erythrocytes and in their nuclei; this outcome has suggested mutagenic and cytotoxic effects, respectively. Based on the current results, MPs are transferred through a food chain that only involves two vertebrates. MPs enter the vertebrates' organs, change their behavior and induce mutagenic and cytotoxic processes in animals, which can cause significant ecological consequences in freshwater ecosystems.

Heavy metal pollution and risk assessment by the battery of toxicity tests

The current study was carried out on dominant fish Oreochromis niloticus and water collected from the polluted Yamuna River, Agra, India. The heavy metals in water, recorded as follows: Fe > Mn > Zn > Cu > Ni > Cr > Cd and all were found to be above the prescribed limits. According to metal pollution index, exposed muscle (49.86), kidney (47.68) and liver (45.26) have been recorded to have higher bioaccumulation. The blood biochemical analysis of exposed O. niloticus indicated significant increase in activities of aspartate aminotransferase (+ 343.5%), alkaline phosphatase (+ 673.6%), alanine aminotransferase (+ 309.1%), and creatinine (+ 494.3%) over the reference. However, a significant decrease in albumin (A): globulins (G) ratio (− 87.86%) was observed. Similarly, the exposed fish also showed significant increase in total leucocyte count (+ 121%), differential leucocyte count, respiratory burst (+ 1175%), and nitric oxide synthase (+ 420%). The histological examination of liver and kidney showed tissue injury. Moreover, micronuclei (0.95%), kidney shaped nuclei (1.2%), and lobed nuclei (0.6%) along with DNA damage in the form of mean tail length in the liver (20.7 µm) and kidney (16.5 µm) was observed in the exposed O. niloticus. Potential health risk assessments based on estimated daily intake, target hazard quotient, hazard index, and target cancer risk indicated health risks associated with the consumption of these contaminated fishes. In conclusion, the present study showed that exposure to heavy metals contaminated water can alter immunological response; induce histopathological alterations and DNA damage in the studied fish. The consumption of this contaminated water or fish could have serious impact on human health.

Mercury Uptake Affects the Development of Larus fuscus Chicks

Current emission and mobilization rates of mercury (Hg) in the environment pose extensive threats to both wildlife and human health. Assessing the exposure risk and effects of Hg contamination in model species such as seabirds is essential to understand Hg risks at the population and ecosystem levels. The lesser black-backed gull (Larus fuscus), a generalist seabird species, is an excellent model species because it forages in both marine and terrestrial habitats, which in turn differ in their Hg exposure risk. To identify possible deleterious effects of Hg exposure on developing L. fuscus chicks, a dietary experiment was carried out and chicks were provided a marine, terrestrial, or mixed diet. The effects of embryonic and dietary Hg exposure on chick body condition and physiological state were assessed at different developmental stages until fledging age (30 d). Overall physiological condition was lower in chicks fed a predominantly marine diet, which coincided with higher Hg loads in blood and primary feathers. However, no effect of dietary uptake of Hg was observed on body condition or in terms of genotoxic damage. Body condition and genotoxic damage correlated instead with Hg exposure during embryonic development, which seems to indicate that embryonic exposure to Hg may result in carry-over effects on later chick development. Environ Toxicol Chem 2020;39:2008-2017. © 2020 SETAC.

Titanium dioxide nanoparticles-induced cytogenotoxicity and alterations in haematological indices of Clarias gariepinus (Burchell, 1822)

The application of titanium dioxide (TiO₂) nanoparticles (NPs) in the manufacturing of consumer products has increased tremendously and with the potential to induce deleterious effects on aquatic biota. There have been reports on metal oxide NP toxicity in aquatic organisms, however, information on cytotoxicity and genotoxicity of TiO₂ NPs on the African catfish, Clarias gariepinus, is scarce. In this study, we investigated the genotoxicity and haematotoxicity of TiO₂ NPs in C. gariepinus using the micronucleus (MN) assay and haematological analysis, respectively. Juvenile C. gariepinus were exposed to 6.25, 12.5, 25.0, 50.0 and 100.0 mg L^-1 concentrations of TiO₂ NPs for 7 and 28 days. Benzene (0.05 mL L^-1) and dechlorinated tap water were used as positive and negative controls, respectively. Data of the MN showed a significant (p < 0.05) concentration-dependent increase in the frequency of MN at both exposure periods in comparison to negative control. Red blood cells, haematocrit, platelets and heterophils significantly reduced with an increased mean corpuscular haemoglobin concentration and lymphocytes at the 7-day exposure period, while in the 28-day exposure period, mean cell volume, mean corpuscular haemoglobin and lymphocytes had a significant increase in comparison with the negative control. This study indicates that TiO₂ NPs induced cytogenetic and haematological alterations in C. gariepinus and is of relevance in biodiversity and aquatic health management.

Comparative metal accumulation and toxicogenetic damage induction in three neotropical fish species with distinct foraging habits and feeding preferences

Environmental pollutants affect fish species differently because their routes of exposure make them more critical to a specific group regarding foraging habits or food preferences. However, the association between local problems and environmental conditions makes a particular species more suitable for use in monitoring programs. Thus, this study compared muscle accumulation of metals (Al, Ba, Cr, Cu, Fe, Mn, Ti and Zn) and toxicogenetic damage to three neotropical species from the Itapemirim River Basin (Brazil) with distinct foraging habits and feeding preferences: Geophagus brasiliensis (benthopelagic - omnivorous); Harttia sp. (benthic - detritivorous); and Leporinus copellandii (pelagic - omnivorous). There was seasonal influence on muscle metal concentrations: Ba and Mn concentrations in G. brasiliensis, Cr in Harttia sp. and Zn, Al and Fe in L. copellandii increased during the rainy season. G. brasiliensis was the most sensitive species, since it had a statistically higher prevalence of erythrocytic nuclear abnormalities, which was influenced by seasonality. This result might be an effect of its benthopelagic habits, which favors contact with a larger group of contaminants due to its interaction with both water column and sediment. The present study showed the differential sensitivity of fish species and that the combination of chemical analysis of pollutants with evaluation of toxicogenetic responses helps to choose the best species for field studies.

Genotoxicity in fishes environmentally exposed to As, Se, Hg, Pb, Cr and toxaphene in the lower Colorado River basin, at Mexicali valley, Baja California, México

The environmental exposure to As, Se, Hg, Pb, Cr and toxaphene was assessed for 11 freshwater fish species in irrigation channels, agricultural return flow drains, a drain collecting lagoon and sections of the Colorado River at the Mexicali valley in Baja California, México, during August 2015-April 2016. Arsenic (2.90 ng ml^-1) and Se (1.41 ng ml^-1) in water had the highest concentrations in the return flow drains (Hardy River and Xochimilco Lagoon, respectively). However, fish axial muscle tissue had the highest concentration of Se (8.3 µg g^-1) and Hg (0.36 µg g^-1) in Colorado River fresh water, while As (1.7 µg g^-1) in Hardy River fish was highest. Selenium concentrations in all fishes and toxaphene in Cyprinus carpio and Ameiurus natalis are above the safe levels for human consumption (0.3 µg g^-1 and 180 ng g^-1 respectively). Toxaphene was detected in the fish axial tissue, having the highest concentrations in Poecilia latipinna (690 ng g^-1) in the Colorado River. The low proportion of the 8-Cl toxaphene congeners in fish suggests degradation of this pollutant. Tilapia. sp. cf. zillii had the most genotoxic damage with 7.4 micronucleated erythrocytes per 10,000 erythrocytes in Xochimilco Lagoon and 2 in Hardy River. The genotoxicity in all the fish species studied was significantly correlated to the concentrations of As and Se in water.

Assessing the seasonal and intrinsic variability of neurotoxic and cyto-genotoxic biomarkers in blood of free-living Eleonoras' falcons

In the present study we investigated seasonal and intrinsic variability of neurotoxic and cyto-genotoxic biomarkers in blood plasma and erythrocytes of free-living Eleonoras' falcons, captured during the pre-breeding (May of 2017 and 2018) and breeding period (September of 2017) on the Antikythira Island (Greece). Specifically, blood samples of captured birds were prepared for the determination of cholinesterase (ChEs, i.e. acetylcholinesterase/AChE and butyrylcholinesterase/ BChE) activity, as well as the formation of nuclear (i.e. the formation of micronuclei into the cells/MN, binucleated cells/BN and others), and cellular/cytoplasmic (i.e. echinocytes/EC, acanthocytes/AC and notched cells/NC) abnormalities in blood plasma and erythrocytes, respectively. Our results indicated that birds sampled in late May had higher ChE and BChE activity levels, as well as higher frequency of total nuclear abnormalities. The latter were also higher in second calendar year (2cy) birds. Cellular/cytoplasmic abnormalities were less frequent in falcons having better body condition, sampled in late May, as well as in light-morph falcons. The observed ChEs activities, as well as nuclear and cellular/cytoplasmic abnormalities revealed that Eleonora's falcons are likely to be exposed to chemical agents with neurotoxic and cyto-genotoxic potential year round, while different aspects of their biology and ecology, such as their reproductive and nutritional status, could mediate their levels. Although we encourage more sampling campaigns to verify the identified seasonal and intrinsic sources of variation in biomarkers tested, the current study enriches the existing knowledge about their usefulness in the environmental monitoring and risk assessment of migratory birds, like Eleonoras' falcon.

Health indicators and contaminant levels of a critically endangered species in the Gironde estuary, the European sturgeon

The European sturgeon, Acipenser sturio, is a highly endangered species that almost disappeared in the last decades. Thanks to yearly restocking of the population, this species is still found in the Gironde estuary (France), where juveniles grow during several years before leaving to the ocean. The aims of this study were to evaluate the pressure exerted on these fish by known organic and inorganic contaminants during their stay at the Gironde estuary, and to get information on the fish's health in this context. Monthly captures over the year 2014 provided 87 fish from the cohorts 2012 and 2013 mainly, and from cohorts 2008, 2009, and 2011, all fish born in hatchery. We report the very first analyses of contaminant levels and of biological markers measured in the blood of these fish. Low inorganic contamination was found, composed of seven metals mainly Zn (< 5 μg mL^-1), Fe (< 1.5 μg mL^-1), Cu (< 0.8 μg mL^-1), Se (< 0.8 μg mL^-1), As (< 0.25 μg mL^-1), Co (< 0.14 μg mL^-1), and Mn (< 0.03 μg mL^-1). Concerning persistent organic contaminants, the sum of seven PCBs varied from 1 to 10 ng g^-1 plasma, that of eight OCPs from 0.1 to 1 ng g^-1, and that of eight PBDEs from 10 to 100 pg g^-1. Higher levels of contaminants were measured during spring as compared to summer. The sex steroid hormone plasma levels (estradiol, testosterone, and 11-ketotestosterone) were quite low, which was predictable for juveniles. The transcription of reproduction-involved genes (EstR, AR, LHR, sox9) in blood cells was demonstrated for the first time. Some of them were correlated with organic contaminant levels PCBs and OCPs. Other gene transcriptions (sodCu and bax) were correlated with PCBs and OCPs. However, the DNA damage level measured here as comet tail DNA and micronuclei ratio in red blood cells were in the very low range of the values commonly obtained in fish from pristine areas. The data presented here can serve as a reference base for future monitoring of this population of sturgeons.

How much are microplastics harmful to the health of amphibians? A study with pristine polyethylene microplastics and Physalaemus cuvieri

Microplastics (MPs) are critical emerging pollutants found in the environment worldwide; however, its toxicity in aquatic in amphibians, is poorly known. Thus, the aim of the present study is to assess the toxicological potential of polyethylene microplastics (PE MPs) in Physalaemus cuvieri tadpoles. According to the results, tadpoles' exposure to MP PE at concentration 60 mg/L for 7 days led to mutagenic effects, which were evidenced by the increased number of abnormalities observed in nuclear erythrocytes. The small size of erythrocytes and their nuclei area, perimeter, width, length, and radius, as well as the lower nucleus/cytoplasm ratio observed in tadpoles exposed to PE MPs confirmed its cytotoxicity. External morphological changes observed in the animal models included reduced ratio between total length and mouth-cloaca distance, caudal length, ocular area, mouth area, among others. PE MPs increased the number of melanophores in the skin and pigmentation rate in the assessed areas. Finally, PE MPs were found in gills, gastrointestinal tract, liver, muscle tissues of the tail and in the blood, a fact that confirmed MP accumulation by tadpoles. Therefore, the present study pioneering evidenced how MPs can affect the health of amphibians.

Using native and invasive livebearing fishes (Poeciliidae, Teleostei) for the integrated biological assessment of pollution in urban streams

Invasive species are increasingly replacing native species, especially in anthropogenically transformed or polluted habitats. This opens the possibility to use invasive species as indicator taxa for the biological assessment of pollution. Integrated biological assessment, however, additionally relies on the application of multiple approaches to quantify physiological or cytogenetic responses to pollution within the same focal species. This is challenging when species are restricted to either polluted or unpolluted sites. Here, we make use of a small group of neotropical livebearing fishes (family Poeciliidae) for the integrated biological assessment of water quality. Comparing urban and suburban stream sections that receive varying degrees of pollution from industrial and domestic waste waters in and around the Brazilian city of Uberlândia, we demonstrate that two members of this family may indeed serve as indicators of water pollution levels. The native species Phalloceros caudimaculatus appears to be replaced by invasive guppies (Poecilia reticulata) at heavily polluted sites. Nevertheless, we demonstrate that both species could be used for the assessment of bioaccumulation of heavy metals (Pb, Cu, and Cr). Ambient (sediment) concentrations predicted concentrations in somatic tissue across species (R²-values between 0.74 and 0.96). Moreover, we used cytogenetic methods to provide an estimate of genotoxic effects of water pollution and found pollution levels (multiple variables, condensed into principal components) to predict the occurrence of nuclear abnormalities (e.g., frequencies of micro-nucleated cells) across species (R² between 0.69 and 0.83). The occurrence of poeciliid fishes in urban and polluted environments renders this family a prime group of focal organisms for biological water quality monitoring and assessment. Both species could be used interchangeably to assess genotoxic effects of water pollution, which may facilitate future comparative analyses over extensive geographic scales, as members of the family Poeciliidae have become invasive in tropical and subtropical regions worldwide.

Difference in biochemical markers in the gibel carp (Carassius auratus gibelio) upstream and downstream of the hydropower plant

However the physiological stress in aquatic organisms associated with hydropower plants (HPP) ecosystems has been previously investigated, no studies have so far assessed it on biochemical level. Therefore this study evaluated an oxidative stress and toxicity in the gibel carp Carassius auratus gibelio associated with a small-scale HPP in the West Ukraine. A battery of liver, brain and blood markers was evaluated individuals inhabiting upstream and downstream of the dam of the small-scale Kasperivtci HPP (KHPP; an installed capacity of 7.5 MW), and from a reference site. Number of alterations were noted in fish from the KHPP impoundment facility including signs of oxidative stress (a decrease in superoxide dismutase (SOD) activity and an increase in protein carbonyls) and cytotoxicity (an increase in micronucleated erythrocytes and caspase-3 activity). No changes in DNA fragmentation in hepatocytes or brain cholinesterase activity were detected. As demonstrated by the integral stress index, fish associated with downstream of the dam revealed the greatest alterations reflected by the combined oppression of antioxidant system (SOD, catalase) and pro-oxidants (thiobarbituric acid reactive substances and oxyradicals), low concentration of metallothioneins, but high cathepsin D activity (as markers of lysosomal dysfunction and autophagy) and increased vitellogenin concentration in males (indicating an endocrine disruption). The study highlights that fish inhabiting ecosystems associated with HPP, particularly downstream of the dam, may face additional stresses with long-term effects yet to be evaluated.

Towards Non-Invasive Methods in Measuring Fish Welfare: The Measurement of Cortisol Concentrations in Fish Skin Mucus as a Biomarker of Habitat Quality

Cortisol levels in fish skin mucus have shown to be good stress indicators in farm fish exposed to different stressors. Its applicability in free-ranging animals subject to long-term environmental stressors though remains to be explored. The present study was therefore designed to examine whether skin mucus cortisol levels from a wild freshwater fish (Catalan chub, Squalius laietanus) are affected by the habitat quality. Several well-established hematological parameters and cortisol concentrations were measured in blood and compared to variations in skin mucus cortisol values across three habitats with different pollution gradient. Fluctuations of cortisol in skin mucus varied across the streams of differing habitat quality, following a similar pattern of response to that detected by the assessment of cortisol levels in blood and the hematological parameters. Furthermore, there was a close relationship between cortisol concentrations in skin mucus and several of the erythrocytic alterations and the relative proportion of neutrophils to lymphocytes. Taken together, results of this study provide the first evidence that skin mucus cortisol levels could be influenced by habitat quality. Although results should be interpreted with caution, because a small sample size was collected in one studied habitat, the measurement of cortisol in skin mucus could be potentially used as a biomarker in freshwater fish.

Genetic and systemic toxicity induced by silver and copper oxide nanoparticles, and their mixture in Clarias gariepinus (Burchell, 1822)

Unanticipated increase in the use of silver (Ag) and copper oxide (CuO) nanoparticles (NPs) due to their antimicrobial properties is eliciting environmental health concern because of their coexistence in the aquatic environment. Therefore, we investigated the genetic and systemic toxicity of the individual NPs and their mixture (1:1) using the piscine micronucleus (MN) assay, haematological, histopathological (skin, gills and liver) and hepatic oxidative stress analyses [malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT)] in the African mud catfish, Clarias gariepinus. The fish were exposed to sublethal concentrations (6.25-100.00 mg/L) of each NP and their mixture for 28 days. Both NPs and their mixture induced significant (p < 0.05) increase in MN frequency and other nuclear abnormalities. There was significant decrease in haemoglobin concentration, red and white blood cell counts. Histopathological lesions observed include epidermal skin cells and gill lamellae hyperplasia and necrosis of hepatocytes. The levels of MDA, GSH and activities of SOD and CAT were impacted in C. gariepinus liver following the exposure to the NPs and their mixture. Interaction factor analysis of data indicates antagonistic genotoxicity and oxidative damage of the NPs mixture. These results suggest cytogenotoxic effects of Ag NPs, CuO NPs and their mixture via oxidative stress in Clarias gariepinus.

Analysis of various effects of abamectin on erythrocyte morphology in Japanese quails (Coturnix japonica)

Although previous studies have already confirmed the toxicological potential of abamectin (ABA) in different experimental models (from invertebrates to vertebrates), almost nothing is known about the impacts the exposure to this pesticide can cause on birds. Thus, the aim of our study is to investigate the cytotoxic effects on the erythrocytes of female Japanese quails (Coturnix japonica) exposed to low abamectin concentrations. In order to do so, three experimental groups were proposed: "control," composed of quails exposed to abamectin-free drinking water; "ABA 1% median lethal dose (LD₅₀)," comprising birds exposed to water containing 15.5 mg a.i./L of abamectin (via commercial formulation Kraft® 36EC), and "ABA 10% LD₅₀," composed by birds exposed to water containing 155.0 mg a.i./L of abamectin. The micronucleus test and the tests applied to other nuclear abnormalities in the peripheral blood of birds were conducted 40 days after exposure. Our study revealed significant physical abnormalities in nuclear shapes (erythrocytes with asymmetric constriction nuclei, notched nuclei, indented and moved nucleus) of those birds exposed to higher abamectin levels. When all nuclear abnormalities were tallied, a significant dose-dependent trend was noted. Therefore, our study presents initial imprints on determination of abamectin-mediated cellular toxicity in avifauna which can be instrumental in checking polluted ecosystems.