Environmentally relevant concentrations of the tricyclic antidepressant, amitriptyline, affect feeding and reproduction in a freshwater mollusc.

Antidepressant drugs (ADDs) are one of the most extensively used pharmaceuticals globally. They act at particularly low therapeutic concentrations to modulate monoamine neurotransmission, which is one of the most evolutionary conserved pathways in both humans and animal species including invertebrates. As ADDs are widely detected in the aquatic environment at low concentrations (ng/L to low µg/L), their potential to exert drug-target mediated effects in aquatic species has raised serious concerns. Amitriptyline (AMI) is the most widely used tricyclic ADD, while monoamines, the target of ADDs, are major bioregulators of multiple key physiological processes including feeding, reproduction and behaviour in molluscs. However, the effects of AMI on feeding, reproduction and mating behaviour are unknown in molluscs despite their ecological importance, diversity and reported sensitivity to ADDs. To address this knowledge gap, we investigated the effects of environmentally relevant concentrations of AMI (0, 10, 100, 500 and 1000 ng/L) on feeding, reproduction and key locomotor behaviours, including mating, in the freshwater gastropod, Biomphalaria glabrata over a period of 28 days. To further provide insight into the sensitivity of molluscs to ADDs, AMI concentrations (exposure water and hemolymph) were determined using a novel extraction method. The Fish Plasma Model (FPM), a critical tool for prioritization assessment of pharmaceuticals with potential to cause drug target-mediated effects in fish, was then evaluated for its applicability to molluscs for the first time. Disruption of food intake (1000 ng/L) and reproductive output (500 and 1000 ng/L) were observed at particularly low hemolymph levels of AMI, whereas locomotor behaviours were unaffected. Importantly, the predicted hemolymph levels of AMI using the FPM agreed closely with the measured levels. The findings suggest that hemolymph levels of AMI may be a useful indicator of feeding and reproductive disruptions in wild population of freshwater gastropods, and confirm the applicability of the FPM to molluscs for comparative pharmaceutical hazard identification.

Catching nano: Evaluating the fate and behaviour of nano-TiO2 in swimming pools through dynamic simulation modelling.

Engineered titanium dioxide nanoparticles (nano-TiO2) in consumer products such as sunscreens widely used by swimmers in aquatic settings have raised concerns about their potential adverse impact on ecosystems and human health due to their small size and unique physicochemical properties. Therefore, this research paper aims to investigate the fate and behaviour of nano-TiO2 from sunscreens in swimming pools using System Dynamics Modelling. The study developed a dynamic simulation model that considers various factors, including weather conditions, sunscreen and pool usage behaviour, filtration efficacy, pool maintenance, water chemistry, pool chemicals, and TiO2 concentration levels, which can affect exposure levels for different scenarios. The study considered non-linear interdependent relationships, feedback structures, and temporal changes and dealt with parameter uncertainties through Monte Carlo analyses. The results reveal that the regular use of sunscreen leads to nano-TiO2 concentrations ranging from 0.001 to 0.05 mg/L within a year, reflecting seasonal and pool usage variations. The study also found that changes in the weight percentage of TiO2 in the sunscreen formulation and the filtration duration per day are the most sensitive factors affecting TiO2 concentrations. Scenario analyses exploring different nano-TiO2 removal strategies suggested that one daily turnover is necessary for sufficient removal. Regular manual pool maintenance and monthly use of a pool clarifier are recommended for enhanced and accelerated removal without substantial additional costs. The study is novel in its integrated approach, combining empirical work with dynamic simulations, resulting in a novel approach to model the environmental fate and behaviour of nano-TiO2. The study makes important methodological contributions to the field and has initiated an interdisciplinary collaboration to create more accurate models. This study is of great significance as it presents a pioneering analysis of the impact of sunscreen properties, user behaviour, and environmental stressors on the fate and behaviour of nano-TiO2 in swimming pools.

Toxicity assessment of polyethylene microplastics in combination with a mix of emerging pollutants on Physalaemus cuvieri tadpoles.

Studies in recent years have shown that aquatic pollution by microplastics (MPs) can be considered to pose additional stress to amphibian populations. However, our knowledge of how MPs affect amphibians is very rudimentary, and even more limited is our understanding of their effects in combination with other emerging pollutants. Thus, we aimed to evaluate the possible toxicity of polyethylene MPs (PE-MPs) (alone or in combination with a mix of pollutants) on the health of Physalaemus cuvieri tadpoles. After 30 days of exposure, multiple biomarkers were measured, including morphological, biometric, and developmental indices, behavioral parameters, mutagenicity, cytotoxicity, antioxidant and cholinesterase responses, as well as the uptake and accumulation of PE-MPs in animals. Based on the results, there was no significant change in any of the parameters measured in tadpoles exposed to treatments, but induced stress was observed in tadpoles exposed to PE-MPs combined with the mixture of pollutants, reflecting significant changes in physiological and biochemical responses. Through principal component analysis (PCA) and integrated biomarker response (IBR) assessment, effects induced by pollutants in each test group were distinguished, confirming that the exposure of P. cuvieri tadpoles to the PE-MPs in combination with a mix of emerging pollutants induces an enhanced stress response, although the uptake and accumulation of PE-MPs in these animals was reduced. Thus, our study provides new insight into the danger to amphibians of MPs coexisting with other pollutants in aquatic environments.

Improving the proteome coverage of Daphnia magna - implications for future ecotoxicoproteomics studies.

Aquatic pollution is an increasing problem and requires extensive research efforts to understand associated consequences and to find suitable solutions. The crustacean Daphnia is a keystone species in lacustrine ecosystems by connecting primary producers with higher trophic levels. Therefore, Daphnia is perfectly suitable to investigate biological effects of freshwater pollution and is frequently used as an important model organism in ecotoxicology. The field of ecotoxicoproteomics has become increasingly prevalent, as proteins are important for an organism's physiology and respond rapidly to changing environmental conditions. However, one obstacle in proteome analysis of Daphnia is highly abundant proteins like vitellogenin, decreasing the analytical depth of proteome analysis. To improve proteome coverage in Daphnia, we established an easy-to-use procedure based on the LC-MS/MS of whole daphnids and the dissected Daphnia gut, which is the main tissue getting in contact with soluble and particulate pollutants, separately. Using a comprehensive spectral library, generated by gas-phase fractionation and a data-independent acquisition method, we identified 4621 and 5233 protein groups at high confidence (false discovery rate < 0.01) in Daphnia and Daphnia gut samples, respectively. By combining both datasets, a proteome coverage of 6027 proteins was achieved, demonstrating the effectiveness of our approach.

Spatial distribution and ecological risks of polychlorinated biphenyls in a river basin affected by traditional and emerging electronic waste recycling in South China.

With development of e-waste related legislation in China, formal recycling activities are designated in some areas while informal ones are illegally transferred to emerging areas to avoid supervision. However, the resulting environmental impact and ecological risks are not clear. Here, we investigated the discharge of polychlorinated biphenyls (PCBs) to soil and aquatic environments by e-waste recycling activities in the Lian River Basin, China. The study area included a designated industrial park in the traditional e-waste recycling area (Guiyu, known as the world's largest e-waste center), several emerging informal recycling zones, and their surrounding areas and coastal area. A total of 27 PCBs were analyzed, and the highest concentration was found in an emerging site for soil (354 ng g-1) and in a traditional site for sediment (1350 ng g--1) respectively. The pollution levels were significantly higher in both the traditional and emerging recycling areas than in their respective upstream countryside areas (p = 0.0356 and 0.0179, respectively). Source analysis revealed that the traditional and emerging areas had similar PCB sources mainly associated with three PCB technical mixtures manufactured in Japan (KC600) and the USA (Aroclor 1260 and Aroclor 1262). The PCB pollution in their downstream areas including the coastal area was evidently affected by the formal and informal recycling activities through river runoff. The ecological risk assessments showed that PCBs in soils and sediments in the Lian River Basin could cause adverse ecotoxicological consequences to humans and aquatic organisms.

Evaluation of water pollution monitoring for heavy metal contamination: A case study of Agodi Reservoir, Oyo State, Nigeria.

Heavy metals affect the suitability of aquatic environment for all purposes; hence, this study evaluated heavy metal contamination in Agodi Reservoir Oyo State, Nigeria. Atomic Absorption Spectrophotometry was used to determine heavy metal concentrations. Heavy Metal Pollution Index (HPI), Water Quality Index (WQI), Pollution Index (PI), Comprehensive Pollution Index (CPI), Contamination Index (CI), Single-Factor Pollution Index (SFPI), Heavy metal Evaluation Index (HEI), and Human Health Risk Assessments (HRA) were used to determine the extent of heavy metal pollution and their impact on the aquatic environment. The order of heavy metal concentrations in both wet and dry seasons was Fe > Mn > Zn > Cu > Cd > Ni > Cr > Pb > Co and Mn > Fe > Zn > Cu > Co > Ni > Cd > Cr > Pb, respectively. WQI for both wet (3182.6) and dry (3649.5) seasons classified the reservoir as "unsuitable for aquatic life." Also, the CPI rated the reservoir to be "severely polluted" in both dry (311.2) and wet (268.7) seasons. Similarly, HEI (951.3 and 2059.7) and Cd (942.3 and 2050.7) rated the reservoir as "highly polluted" in wet and dry seasons, respectively. The Hazard Quotient (HQ ingestion) was in the order of Mn > Cu > Cd > Zn > Fe > Co > Ni > Cr > Pb in the dry season while the order was Cu > Mn > Cd > Fe > Zn > Ni > Pb > Co > Cr in the wet season. The HQ ingestion revealed that Cr (0.00), Ni (0.33; 022), and Pb (0.00; 0.06) were the only metals with HQ values lesser than 1 (HQ < 1) while the values of HQ (dermal) were less 1 (HQ < 1) indicating that there was no health risk in association with the domestic use of the water. The pollution level of the reservoir means that urgent attention is needed from different agencies for the conservation, management, and sustainable development of the reservoir.

Exposure and Transport of Alkaloids and Phytoestrogens from Soybeans to Agricultural Soils and Streams in the Midwestern United States.

Phytotoxins are naturally produced toxins with potencies similar/higher than many anthropogenic micropollutants. Nevertheless, little is known regarding their environmental fate and off-field transport to streams. To fill this research gap, a network of six basins in the Midwestern United States with substantial soybean production was selected for the study. Stream water (n = 110), soybean plant tissues (n = 8), and soil samples (n = 16) were analyzed for 12 phytotoxins (5 alkaloids and 7 phytoestrogens) and 2 widely used herbicides (atrazine and metolachlor). Overall, at least 1 phytotoxin was detected in 82% of the samples, with as many as 11 phytotoxins detected in a single sample (median = 5), with a concentration range from below detection to 37 and 68 ng/L for alkaloids and phytoestrogens, respectively. In contrast, the herbicides were ubiquitously detected at substantially higher concentrations (atrazine: 99% and metolachlor: 83%; the concentrations range from below detection to 150 and 410 ng/L, respectively). There was an apparent seasonal pattern for phytotoxins, where occurrence prior to and during harvest season (September to November) and during the snow melt season (March) was higher than that in December-January. Runoff events increased phytotoxin and herbicide concentrations compared to those in base-flow conditions. Phytotoxin plant concentrations were orders of magnitude higher compared to those measured in soil and streams. These results demonstrate the potential exposure of aquatic and terrestrial organisms to soybean-derived phytotoxins.

Effects of antibiotic norfloxacin on the degradation and enantioselectivity of the herbicides in aquatic environment.

Antibiotics are currently extensively used in human medicine, animal farming, agriculture and aquaculture, and their residue has become a global environmental problem. However, the effects of antibiotic on other pollutants in aquatic environment are still poorly understood. In this study, the influences of norfloxacin on the residue, degradation and distribution of the herbicides (simazine, atrazine, terbuthylazine, acetochlor and metolachlor) and the enantioselectivity of acetochlor in sediment and water-sediment microcosm system were investigated. Sediment was spiked with norfloxacin and water was contaminated by herbicides to simulate environmental pollution. The amounts of herbicides in water and sediment samples were analyzed within 30 days of cultivation. The results showed that norfloxacin could significantly inhibit the dissipation, lengthen the half-lives and enhance the residues of herbicides in sediment. Take simazine as an example, its half-life significantly increased from 16.1 days to 19.3 days and its residual percentage grew from 24.2% to 30.4% when sediment was contaminated with 5 mg·kg-1 norfloxacin. However, only acetochlor degradation was significantly inhibited by norfloxacin in water-sediment microcosm and the distribution of the herbicides were not affected. Enantioselective degradation of acetochlor was observed both in control and norfloxacin-treated water-sediment system, with R-acetochlor preferential elimination, suggesting the co-existence of norfloxacin had very limited influence on the enantioselectivity. The findings indicated that co-contamination with norfloxacin could increase the persistence of herbicides in aquatic environment, thus increasing the environmental risks to aquatic organisms.

Genotoxicity, oxidative stress and lysozyme induction in Clarias gariepinus chronically exposed to water-soluble fraction of burnt tire ash.

The safety of aquatic ecosystems has been compromised by numerous anthropogenic activities, especially leachates from non-point source toxicants, leaching into aquatic systems. This study evaluated the toxicity of the water-soluble fractions (WSFs) of burnt tire ash (BTA) on Clarias gariepinus via a battery of integrated biomarkers. Juvenile C. gariepinus were exposed to sublethal (0.56, 1.12, and 2.24 g/L) concentrations of BTA, derived from 11.2 g/L median lethal concentration (96 LC50), at duration intervals of 1, 14, and 28 days, followed by a recovery trial that lasted for 14 days. Serum biochemical parameters, antioxidant enzyme activities of the gill and liver, lysozymes activity and erythron profile were assessed. The findings of the present study revealed that BTA-WSF induced prominent alterations on biochemical parameters, lysozymes activity and antioxidant enzymes activities in the exposed fish. Furthermore, toxicant exposure promoted oxidative stress, cellular damage and genotoxicity (erythrocytic nuclear and cellular abnormalities) in the exposed fish. In general, a post-exposure trial showed partial recovery from the exposure effects of the toxicant, following the evident modifications of serum enzymes and erythron pathopathology in the experimental model. Biomonitoring of BTA, using sentinel aquatic species such as C. gariepinus, provides insights into the ecotoxicological potency of this toxicant.

Gene Expression Changes in Epinephelus marginatus (Teleostei, Serranidae) Liver as Molecular Biomarker of Iron Ore Contamination.

The aim of this study was to determine selected molecular biomarkers of iron ore contamination in Epinephelus marginatus. Molecular biomarkers were tested by checking the relative expression of genes involved in oxidative stress, trace element regulation, and cellular damage, by RT-qPCR. Iron ore exposure caused the downregulation of ferroportin (FP) gene expression and a significant upregulation in superoxide dismutase (SOD) and cytochrome P450 1A (CYP1A) genes. Iron ore affects gene expression in E. marginatus liver, indicating that it can potentially induce toxic effects in fish. Moreover, this altered gene expression pattern may be applied in monitoring iron ore contamination in marine environments.

Environmental concentrations of sulfamethoxazole increase crayfish Pacifastacus leniusculus susceptibility to White Spot Syndrome Virus.

Antibiotics used for humans and livestock are emerging as pollutants in aquatic environments. However, little is known about their effect on aquatic organisms, especially in crustaceans. In the present study, the freshwater crayfish Pacifastacus leniusculus was exposed during 21 days to environmental concentrations of sulfamethoxazole (SMX) (100 ng/L and 1 µg/L). Subsequently, the crayfish susceptibility to infection was evaluated by using White Spot Syndrome Virus (WSSV) challenge, a well-known crustacean pathogen. The median survival time of the infected crayfish exposed to 100 ng/L SMX was one day, whereas the control and the group exposed to 1 µg/L SMX survived for two and three days, respectively. In order to elucidate the effect of SMX upon the crayfish immune response, new sets of crayfish were exposed to the same SMX treatments to evaluate mRNA levels of immune-related genes which are expressed and present in hemocytes and intestine, and to perform total and differential hemocyte counts. These results show a significant down-regulation of the antimicrobial peptide (AMP) Crustin 3 in hemocytes from the 100 ng/L SMX group, as well as a significant up-regulation of the AMP Crustin 1 in intestines from the 1 µg/L SMX group. Semigranular and total hemocyte cell number were observed to be significantly lower after exposure to 100 ng/L SMX in comparison with the control group. The present study demonstrates that environmentally relevant SMX concentrations in the water at 100 ng/L led to an increased WSSV susceptibility, that may have been caused by a reduction of circulating hemocytes. Nevertheless, SMX concentrations of 1 µg/L could marginally and for a few days have an immunostimulatory effect.

Transcriptomic responses to pollution in natural riverine environment in Rita rita.

Aquatic pollution is one of the most common threats to the ecological health of aquatic ecosystems and its biota. Fish as lower vertebrates are excellent model to study the impact and responses of aquatic pollution. In fish, gill is the main organ indicator of whole animal health as it comes in contact with the surrounding water and absorbs many pollutants and contaminants; therefore, investigations on alterations in fish gill at transcriptome level could provide newer insights to the stress response mechanism(s) and pathways. For comprehensive evaluation of the impacts of pollutants (joint toxicity) prevalent in the riverine environment, comparative transcriptome analysis, by Next Generation Sequencing under Illumina HiSeq 2500 platform, was carried out in gill tissues of Rita rita collected from two stretches of river Ganga (Kanpur and Farakka) and results were validated by RT-qPCR. Out of 154,077 unigenes (Accession SRR548008), a total of 2024 differentially expressed genes (DEGs) including 942 up-regulated and 1082 down-regulated genes were identified by DESeq program. Further, Gene Ontology (GO) of DEGs showed that ribosomal large subunit biogenesis, mitochondrial ribosome and box H/ACA SnoRNA binding categories are highly affected by pollution. Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis showed the involvement of the DEGs in energy metabolism, translational and transcriptional machinery, protein folding and degradation suggesting that these signalling pathways are highly affected by aquatic pollution. Among the DEGs, up-regulation of cytochrome c oxidase subunit (cox) 7a2 (69.47 fold), hsp70 subunit 14 (hsp70-14, 5.27 fold), muscle related coiled-coil protein (MURC, 21.55 fold), lysozyme G (40.14 fold), cox17 (29.36 fold) were the conspicuous ones which showed similar trends in expression when analysed by RT-qPCR. Based on fold change, perturbation values, correlation analysis by PCA and RT-qPCR validation, up-regulation of cox7a2, MURC and hsp70-14 appeared to be the most promising biomarker responses and could be useful in the evaluation of gill health and possibly be extended towards aquatic ecosystem health assessment.

Treated Textile Effluents: Cytotoxic and Genotoxic Effects in the Natural Aquatic Environment.

Textile effluent treatment methods use biological and chemical treatments to reduce the toxicity and to comply with standard effluent discharge limits. However, trace amounts of pollutants can affect the biological organisms in the receiving environment. The present study used Allium cepa bio assay to assess the cytotoxic and genotoxic effects of treated textile effluents discharged to the natural environment. The results of the bioassay indicated that treated textile effluents can induce alterations in the mitotic index. Also nuclear buds, bi nuclei, condensed nuclei, were recorded in the bioassay and the severity of them decreased towards downstream of the effluent discharge point. Therefore, it can be concluded that even the discharged effluents comply with the standard limits, there is a possibility of causing cytotoxic and genotoxic effects in the organisms living in the natural environment.

Prevalence and diversity of blaTEM, blaSHV and blaCTX-M variants among multidrug resistant Klebsiella spp. from an urban riverine environment in India.

In the present study, we have investigated prevalence and diversity of ESBL genes among Klebsiella isolates obtained from highly polluted stretch of river Yamuna, India. Phenotypic screenings of 116 Klebsiella isolates revealed ~30% were positive for ESBL production. Antibiotic profiling showed multidrug resistance phenotype among 90% isolates. Prevalence of blaTEM, blaSHV and blaCTX-M genes were found to be 57, 54 and 48% respectively. Furthermore, we identified eight variants of blaSHV (SHV-1, SHV-11, SHV-27, SHV-28, SHV-38, SHV-61, SHV-144, SHV-148), three each of blaTEM (TEM-1, TEM-116, TEM-206) and blaCTX-M (CTX-M-15, CTX-M-55, CTX-M-188) among Klebsiella spp. Co-occurrence of blaTEM, blaSHV and blaCTX-M (any two or all three) was observed among 45% Klebsiella isolates. Occurrence of blaCTX-M-188 and blaTEM-206 in environmental isolates of K. pneumoniae has not been reported earlier. Identification of blaTEM-206, blaSHV-27 and blaSHV-144 from Klebsiella spp. and blaTEM-116 from K. quasipneumoniae and K. variicola is the first report from India.

Assessment of biomarkers in the neotropical fish Brycon amazonicus exposed to cypermethrin-based insecticide.

The effects of cypermethrin-based insecticide (CBI), commonly used in aquaculture and agriculture, were evaluated in matrinxa (Brycon amazonicus) exposed to sub-lethal concentration (20% of LC50) for 96 h. Physiological and biochemical effects were studied through biomarkers: lipid peroxidation (LPO), glutathione (GSH), and ascorbic acid concentrations; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glucose-6-phosphate dehydrogenase (G6PDH) assays in the liver and gills. Besides, ions Na+, Cl-, and K+; protein and glucose concentrations were measured in the plasma. Red blood cells count (RBC), hemoglobin concentration (Hb), hematocrit (Ht), and hematimetric parameters were evaluated in the total blood. The NKA (Na+ /K+ ATPase) activity was assayed in the gills. The histopathological effects of CBI were also investigated in the gills. The liver and gill LPO increased 62 and 100%, respectively. The tripeptide GSH concentration reduced in the liver and increased in the gill of exposed fish. The SOD and CAT activities increased in the liver, whereas CAT reduced in the gill. Liver also presented an increase in G6PDH activity. Plasma Na+ and Cl- and glucose concentrations increased in the exposed fish. Levels of Ht, Hb and RBC were significantly increased. The gill NKA activity also increased. Exposed fish exhibited histological alterations in the gills such as hypertrophy and proliferation of chloride cells, blood vessels dilation, aneurysms and hemorrhage of the lamella. The histological index indicated moderate to heavy damage to the gills. CBI provokes liver and gills oxidative stress, gill structural damages, and ionic imbalance. A multi-biomarker approach allows us to see that B. amazonicus was unable to cope with CBI exposure.

Contamination by lead in sediments at Toledo River, hydrographic basin of PARANÁ III.

Due to intense agricultural and industrial activities, the environment has been affected by increasing amounts of pollutants, such as lead, a toxic heavy metal. When introduced to the environment, toxic metals are distributed and incorporated into the liquid medium, sediments, and aquatic biota; bioaccumulating. This research aimed to identify and quantify the levels of toxic metals present in the waters and sediments of Toledo River, compare the obtained results with legislation and other studies, as well as to evaluate the possible pollutant sources of the water body. Six water and sediment samples were taken at seven strategic sites. The concentrations of Cu, Zn, Fe, Mn, Cd, Pb, and Cr in water were compared to the maximum limits established by Brazilian legislation IN CONAMA No. 357/05, for class II fresh waters. The sediment samples were submitted to nitroperchloric digestion, and then the total concentrations of the metals were determined by flame atomic absorption spectrometry (FAAS). The toxicological quality of the Toledo River has been considerably affected by the activities carried out in its surroundings, such as extensive areas of agriculture, pig farming and industrial areas, causing concentrations of Cd, Fe, and mainly Pb, which is observed at concentrations higher than value allowed by the legislation.

Assessment of surface water using Allium cepa test and histological analysis in Rhamdia quelen.

This study aimed to assess the cytotoxic, genotoxic, and mutagenic potentials of water samples collected in the Alegre River Basin, located in a predominantly rural area with no sewage treatment facilities in the Espírito Santo State, Brazil, using Allium cepa test. Also, gills and liver of Rhamdia quelen, a common fish species of the region, were histologically analyzed. A semi-quantitative analysis was performed and a histopathological alterations index (HAI) was determined. Our findings indicated that the waters of this river basin were cytotoxic (mitotic index reduction) and/or genotoxic (chromosomal abnormalities induction). Mutagenicity (micronuclei induction) was not observed for any water sample. The values for HAI showed that the waters caused moderate histological alterations in R. quelen. Liver was more sensitive than gills. It is necessary to implement a sewage treatment system and raise awareness on inappropriate management and disposal of agrochemicals in order to allow the recovery of Alegre River.

Toxicological Assessment of Heavy Metal Bioaccumulation and Oxidative Stress Biomarkers In Clarias gariepinus from Igbokoda River of South Western Nigeria.

This study evaluated the environmental safety of Igbokoda River, a popular fishing hub in an oil producing area in Nigeria. Biomarkers of oxidative stress and heavy metals were determined in the liver and muscle of Clarias gariepinus from Igbokoda River and also in fish samples from a clean fish farm (control). Water samples from both sites were analysed for physicochemical parameters, heavy metals and bacterial contamination. There was significant increase in the level of heavy metals in water samples and in the organs of fish from Igbokoda River. A significant increase in malondialdehyde level as well as alterations in antioxidant status was observed in the organs of fish samples from Igbokoda River compared with control. Coliforms and salmonella were also visible in Igbokoda River alongside particulate matter. These results show that Igbokoda River is polluted; consumption of aquatic organisms from the River may be unsafe for people in that community.

Enantioselective accumulation, metabolism and phytoremediation of lactofen by aquatic macrophyte Lemna minor.

Pesticides are frequently detected in water bodies due to the agricultural application, which may pose impacts on aquatic organisms. The enantioselective bioaccumulation and metabolism of the herbicide lactofen in aquatic floating macrophyte Lemna minor (L. minor) were studied and the potential L. minor phytoremediation was investigated. Ultra-high performance liquid chromatography - tandem mass spectrometry (UHPLC-MS-MS) analysis for lactofen and its two known metabolites in L. minor was performed. The initial concentrations of racemic lactofen, R-lactofen and S-lactofen were all 30µgL-1 in the growth solution. The distribution of lactofen and its metabolites in growth solution and L. minor was determined throughout a 5-d laboratory trial. It was observed that S-lactofen was preferentially taken up and metabolized in L. minor. After rac-lactofen exposure, the accumulation amount of S-lactofen was approximately 3-fold more than that of R-lactofen in L. minor and the metabolism rate of S-lactofen (T1/2=0.92 d) was significantly faster than R-lactofen (T1/2=1.55 d). L. minor could only slightly accelerate the metabolism and removal of lactofen in the growth solution. As for the metabolites, desethyl lactofen was found to be the major metabolite in L. minor and the growth solution, whereas the metabolite acifluorfene was undetectable. No interconversion of the two enantiomers was observed after individual enantiomer exposure, indicating they were configurationally stable. The findings of this work represented that the accumulation and metabolism of lactofen in L. minor were enantioselective, and L. minor had limited capacity for the removal of lactofen and its metabolite in water.

Dietary ascorbic acid reduced micronucleus and nuclear abnormalities in Clarias gariepinus (Burchell 1822) exposed to hospital effluent.

Hospital effluents contain myriad of mutagens and genotoxins capable of increasing DNA damage in aquatic biota. African mudfish, Clarias gariepinus, are exposed to genotoxins when cultured in swamps and derelict water bodies often contaminated by effluents. Moreover, its DNA is susceptible to xenobiotic-induced lesions since it lacks L-gulonolactone oxidase and hence cannot synthesize L-ascorbic acid. This study investigated 96-h acute toxicity and protective effects of dietary ascorbic acid (AA) against micronucleus (MN) and abnormal nuclear (NAs) formation in C. gariepinus exposed to sub-lethal concentrations of hospital effluent. Six concentrations (0.5-3.0%) of the effluent were selected to determine the 96-h acute toxicity of the effluent in C. gariepinus, after range finding test. Fish were exposed to sub-lethal concentrations (0.08-1.30%) of the 96 h LC50. Two other groups were exposed to the 96 h LC50 (1.30%) of the effluent +50 and +100 mg/kg of dietary ascorbic for 7 days, and MN and NAs assessed in peripheral erythrocytes. The 96 h LC50 (1.30%) was 1.18 times more toxic than the 24 h LC50 (1.54%), indicating that the toxicity of the effluent increased with exposure duration. MN, nuclear bud, enucleated, fragmented nucleus (apoptosis), and necrotic erythrocytes significantly increase in effluent treated fish. Dietary AA reduced MN from 6.35-fold (1.30% treated group) to 3.72-fold (1.30% + 50 mg AA) and 3.54-fold (1.30% + 100 mg AA). Also, AA reduced total NAs from 2.26-fold (1.30%) to 1.40-fold (1.30% + 50 mg AA) and 1.06-fold (1.30% + 100 mg AA) compared to the control. Heavy metals and physicochemical parameters analyzed in the tested effluent possibly induced the mortality and cytogenotoxicity in C. gariepinus, and this was ameliorated by dietary AA.