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The impact of emerging pollutants such as ibuprofen and dibutyl phthalate on aquatic species is a growing concern and the need for proper assessment and evaluation of these toxicants is imperative. The objective of this study was to examine the toxicogenomic impacts of ibuprofen and dibutyl phthalate on Clarias gariepinus, a widely distributed African catfish species. Results showed that exposure to the test compounds caused significant changes in gene expression, including upregulation of growth hormone, interleukin, melatonin receptors, 17β-Hydroxysteroid Dehydrogenase, heat shock protein, doublesex, and mab-3 related transcription factor. On the other hand, expression of forkhead Box Protein L2 and cytochrome P450 was downregulated, revealing a potential to induce female to male sex reversal. The binding affinities and hydrophobic interactions of the test compounds with the reference genes were also studied, showing that ibuprofen had the lowest binding energy and the highest affinity for the docked genes. Both compounds revealed a mutual molecular interaction with amino acids residues within the catalytic cavity of the docked genes. These results provide new insights into the toxic effects of ibuprofen and dibutyl phthalate on Clarias gariepinus, contributing to a better understanding of the environmental impact of these pollutants.

The experiment explored the impacts of polycyclic aromatic hydrocarbons (PAHs) and the prevalence of Aspidogastrea africanus (endoparasite) in Chrysichthys nigrodigitatus (host) in Lekki lagoon, Lagos State, Nigeria. Host-parasite allotment of PAHs, histopathological analysis, and the oxidative status of parasite and host were investigated. Oxidative status of fish and endoparasites were determined by assessing the levels of reduced glutathion (GST), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA). PAH concentrations were determined in the tissues of the host and parasite using gas chromatograph coupled to flame ionization detector (GC-FID). Physico-chemical parameters of water and sediment were assessed using a handheld multi-parameter probe (Horiba Water Checker Model U-10). The parasitic prevalence in the examined fish was proportional to length and weight of fish individuals. The parasites were more predominant among the length and weight cohorts of the female fishes than the males. Higher induction of oxidative stress enzymes in the intestine of the male C. nigrodigitatus than in the female, and the parasite can be attributed to the higher levels PAH and partly absence of parasites to depurate the toxicant in the fish. A. africanus shared the toxic burdens of chrysene, benzo(b)fluoranthene, dibenz(a,h)anthracene, benzo(g,h,i)perylene, dibenzo(a,l)pyrene, dibenzo(a,i)pyrene and particularly indo(1.2,3-cd)pyrene from the intestine of both sexes. In return, the endoparasite contributed to the oxidative stress in the intestine of the fish. Synergistic and antagonistic interactions between PAH congeners and A. africanus on silver catfish, C.nigrodigitatus is evident in the current study. We suggest mitigation of PAH-releasing anthropogenic activities around Lekki lagoon for the protection of C. nigrodigitatus. Keywords: Polycyclic aromatic hydrocarbons, Silver catfish, Parasite intensity, Oxidative stress, Bioaccumulation factor

The study was carried out on 120 randomly selected fresh specimens of Chrysichthys nigrodigitatus (males and females of different trophic levels) from Lekki lagoon, Lagos, Nigeria. The aim was to investigate the heavy metals and endoparasitic infection in the fish. We compared the impacts of both stressors on the liver and intestine of C. nigrodigitatus. Water samples were tested for pH, dissolved oxygen (DO), salinity, electrical conductivity, total dissolved solids using a multiprobe meter. Nitrate, nitrite, phosphorus, ammonia, total suspended solids and colour were measured using VR 5000 spectrophotometer. Alkalinity, acidity, biological oxygen demand (BOD) and chloride were measured via Titrimetry method. Chemical oxygen demand (COD) was measured via a closed reflux titration., and turbidity was measured via a VR 2010. Aspidogastrea africanus was the only parasitic infection detected in C. nigrodigitatus; though of low intensity. We also observed low heavy metal levels in the environmental media tested. However, the study showed that the liver and intestinal tissues of C. nigrodigitatus were slightly impacted by the stressors even at low levels. We therefore suspect synergy between Aspidogasrea infection and heavy metals toxicity. We recommend a further biomonitoring of the aquatic environment in order to ascertain the actual causative factors contributing to tissue injuries in the fish. Findings will help mitigate future aggravation of the tissue toxicity. Low levels of Aspidogastrea infection is an early prognostic information against outbreak of the disease in the aquatic environment. Keywords: Parasite intensity, Chrysichthys nigrodigitatus, Heavy metals, Histopathology, Stressor, Synergy

Background. The presence of heavy metals in the aquatic environment is a concern because of potential toxicity and threats to plant and animal life. Objective. The present study evaluated the joint action toxicity and biochemical effects of sublethal concentrations of copper (Cu), lead (Pb) and cadmium (Cd) against Clarias gariepinus over a period of 28 days. Methods. We procured fingerlings (weight: 5–8 g; length: 4.5–6.0 cm) and juveniles (weight: 20–25 g; length: 14.5–17.5 cm) from a commercial fish farm in Bariga, Lagos state, Nigeria. Test toxicants were selected from the analyzed heavy metals in the field based on their deviation from World Health Organization, Federal Environmental Protection Agency and United States Environmental Protection Agency standards. Fish were randomly loaded into a 4-L glass aquaria for the bioassay per toxicant concentration of two replicates and untreated control (dechlorinated tap water). Results. The derived 96 hour lethal concentration 50 (LC50) value of Cu (2.11 mg/L) was the most toxic followed by Cd (24.18 mg/L) and Pb (34.48 mg/L), which was the least toxic of the singly tested pollutants. The analysis of dose-response data of the joint action toxicity of Cu and Cd, and Cu and Pb determined 96 hour LC50 values of 1.804 mg/L and 2.15 mg/L, respectively. The interactions between the mixture of Cu:Cd conformed with the model of synergism (synergistic ratio (SR)>1 and relative toxic units (RTU)>1), while the interaction between Cu:Pb was found to be antagonistic (SR

This study was carried out to assess the heavy metal pollution status and potential ecological risk in the Lagos lagoon, Nigeria. The concentrations of twelve heavy metals commonly associated with environmental pollution were determined in the sediments of the lagoon by Atomic Absorption Spectrophotometry (AAS) and the cold vapor method was employed for Mercury (Hg). Nonempirical risk indices and empirical Sediment Quality Guidelines (SQGs) were used to assess the ecological risk associated with heavy metal in the sediments. The nonempirical risk indices showed that Hg, Arsenic (As), and Cadmium (Cd) are the major contributors to the ecological risk associated with heavy metal pollution in the ecosystem. Comparison of heavy metal concentrations to the Screening Quick Reference Table (SQuiRT) showed that mean concentration of Cd (5.22 and 4.88 mg kg−1in dry and rainy seasons, respectively) exceeds the effect range low (ERL) value (1.20 mg kg−1) in effect to biota. Industries sited around the lagoon have effluent output points in the lagoon serving as a major source of heavy metals coupled with indirect discharges from other sources. Heavy metals are nonbiodegradable, toxic and have the potential to alter ecosystem health, thus pollution sources should be effectively monitored and contained. [ABSTRACT FROM PUBLISHER]