Geotaxis is the behaviour of an organism in response to gravitational forces. Mosquito larvae display innate negative geotaxis in water. This study explored how exposure to pymetrozine (PYM) and manganese (Mn) affects the geotaxis of Culex sp. larvae in water, and whether this behaviour could be a useful endpoint in aquatic ecotoxicology. Culex sp. larvae were exposed to varying concentrations of both chemicals, and their geotaxis was monitored for ten min. Additionally, 24-hr mortality bioassays were carried out to obtain novel data on the lethal effects of both chemicals on Culex sp. larvae. Mortality experiments revealed that PYM caused significant larval mortality with an LC50 of 60.75 (54.29-67.98) mg/L. Mn showed a moderate lethal effect with an undetermined LC50 value due to insufficient mortality across the tested concentration range (i.e., 0-345.50 mg Mn/L). Geotaxis testing revealed that in the control, the mosquito larvae spent, on average, 78.23% of their time in negative geotaxis. Exposure to Mn significantly decreased this innate rate to 62.71% in the 172.75 mg Mn/L treatment (p < 0.05), whereas exposure to PYM lowered it further to 54.54% in the 8.25 mg PYM/L treatment (p < 0.05). These significant reductions in negative geotaxis in contaminated water samples suggest that geotaxis could serve as a useful endpoint for the quick assessment of water pollution. However, because the geotaxis dose-response curves were biphasic, validation using other aquatic life forms may be required, especially at lower concentrations, to ensure that systemic shutdown in the larvae at higher concentrations is not misinterpreted as genuine geotaxis responses.

S. The spread of impermeable surfaces in urban coastal areas increases runoff, carrying pollutants that degrade surface water quality and impact the stress responses of coastal fauna. This study investigated oxidative stress and gonad health in male and female Callinectes amnicola (blue crabs) from urban and suburban regions of Lagos Lagoon. Gonadal damage in the crabs was linked to estrogenic metals (Cu, Zn, Pb, Cd) and antioxidant responses (MDA, GSH, GPx, CAT, and SOD). Urban male crabs showed higher oxidative stress, with elevated MDA and lower GSH and CAT levels, alongside regressive gonadal changes due to increased Pb, Cd, and Zn exposure. Suburban crabs, however, displayed more intersex conditions (ovotestes) correlated with elevated Cu levels in lagoon sediment. These results highlight severe testicular disruption in urban males and ovarian dysgerminomas in suburban females, indicating a sex-specific impact of pollution on reproductive health. The study identifies two primary reproductive toxicity risks: (1) male testicular damage and regressive lesions in urban crabs, caused by increased lipid peroxidation and oxidative stress, and (2) female endocrine disruption, with ovotestes in suburban populations potentially leading to nonviable follicles. These findings emphasize that urban blue crabs face significant risks across both sexes, while suburban populations are more affected by female-specific risks. The study underscores the need for targeted environmental management to address the different stressors impacting these populations.

We investigated the occurrence, species-specific distribution, accumulation, and biomagnification of poly- and perfluoroalkyl substances (PFAS) in three teleost fish species (Sarotherodon melanotheron, Clarias gariepinus, and Chrysicthys nigrodigitatus), as well as molluscs (Pachymelania aurita), earthworms (Lumbricus terrestris), and sediment samples from the Ologe Lagoon in Nigeria, which receives complex mixtures of anthropogenic effluents from various sources. Total ∑PFAS concentrations (ng/g) were significantly highest in earthworms (16.2), compared to teleost species (S. melanotheron (1.8), C. gariepinus (1.2), and C. nigrodigitatus (1.8)) and molluscs (0.4). The novel precursor diSAMPAP was the dominant PFAS congener in S. melanotheron and C. gariepinus, while PFOS and diSAMPAP were highest in C. nigrodigitatus. In earthworms, molluscs, and sediment, diSAMPAP, PFBS, and PFOS were the dominant PFAS. We calculated the biota sediment accumulation factor (BSAF), revealing that diSAMPAP in S. melanotheron and 8:2 FTS in earthworms exhibited the highest BSAF values. Species-specific differences in PFAS biomagnification factor (BMF) suggest varying exposure routes among the examined fish species. Notably, PFOS concentrations in the liver were significantly higher than in flesh tissues for C. gariepinus and C. nigrodigitatus, indicating organ-specific accumulation. Risk analysis using the Risk21 tool showed that S. melanotheron had the highest public health risk, while C. gariepinus had the least risk. Our results highlight significant food safety concerns and public health risks associated with the occurrence, species-specific distribution, accumulation, and biomagnification of diSAMPAP, 8:2 FTS, and PFOS in the Ologe Lagoon and its aquatic food webs. This study contributes valuable insights to global PFAS monitoring efforts, particularly in fluvial tropical ecosystems such as those found in Nigeria.

Petroleum refinery effluents pose severe environmental and health risks due to their complex mixture of toxic pollutants, including polycyclic aromatic hydrocarbons (PAHs), heavy metals, and volatile organic compounds, which contaminate soil, water, and agricultural systems while threatening human health through carcinogenic and mutagenic effects. This review comprehensively evaluates sustainable bioremediation techniques for treating petroleum wastewater, analyzing their mechanisms, effectiveness, and potential for agricultural reuse. Major findings reveal that biological treatment methods, including bioaugmentation, biostimulation, composting, enzymatic bioremediation, and phytoremediation, achieve excellent removal efficiencies for various contaminants, with microbial consortia demonstrating superior performance compared to individual strains. Key bacterial genera (Pseudomonas, Rhodococcus, Acinetobacter) and factors affecting bioremediation success, including temperature, pH, nutrient availability, and contaminant bioavailability, were identified. Advanced approaches such as hybrid bioelectrochemical systems and genetically modified microorganisms show enhanced degradation capabilities, while integrated treatment strategies combining biological and physicochemical methods offer the most promising results for complex refinery effluents. The findings highlight that treated petroleum wastewater can serve as a valuable resource for agricultural irrigation, providing essential nutrients while reducing freshwater demand, though careful monitoring is required to prevent micropollutant accumulation. Despite challenges, including site-specific optimization requirements, long-term stability concerns, and scaling limitations, bioremediation represents a cost-effective, environmentally sustainable solution for petroleum wastewater management. Research should focus on developing novel microbial strains, optimizing integrated treatment systems, and establishing comprehensive monitoring protocols to ensure safe agricultural reuse while advancing toward circular economy principles in the petroleum industry.

Algal blooms along the West African coast threaten ecosystems and human health due to nutrient enrichment and rising temperatures. This remote-sensing study examined the relationships between chlorophyll-a concentrations, environmental variables, and the potential for microplastic retention in blooms using molecular docking models for predictive insights. Correlation analyses revealed region-specific associations, with moderate positive correlations between chlorophyll and temperature along the southwest Nigeria-Togo coastline and near Liberia and Sierra Leone (r = 0.2-0.4) and strong correlations with particulate carbon across most regions (r = 0.6-0.8). Chlorophyll fluorescence correlations were generally low (r = 0.2), except for higher correlations in the Senegal-Gabon and Cote d ' Ivoire-Ghana stretches, indicating that localized factors influence bloom dynamics. Molecular docking results predict that polycarbonate microplastics have the strongest binding affinities with algal proteins, particularly flagellin (-11.3 kcal/mol), suggesting significant retention potential within bloom matrices. In contrast, ethylene plastics displayed weaker interactions (up to-2.2 kcal/mol) and a high dissociation constant (Kd = 0.079 M), indicating minimal retention potential. The low Kd values for polycarbonate-protein interactions (e.g., 5.15e-09 M for flagellin) predict a concerning scenario where microplastics become increasingly integrated into algal biomass, increasing exposure risks for marine life. Warm, nutrient-rich conditions along the West African coast, especially from southwest Nigeria to Togo and Cote d ' Ivoire to Sierra Leone, are expected to increase the frequency and severity of algal blooms. This proliferation disrupts biodiversity and water quality while straining local fisheries by altering marine food webs. To mitigate microplastic entrapment from algal blooms and protect vulnerable marine ecosystems, targeted monitoring and intervention strategies are essential.

Fluorene (FL), a low-molecular-weight polycyclic aromatic hydrocarbon (PAH), is increasingly detected in freshwater environments, yet its mechanistic toxicity remains poorly characterized. This study evaluated FL-induced toxicity in Bellamya bengalensis (BB) and Anabas testudineus (AT) under acute (96hrs) and chronic exposures (28 and 45 days respectively). Acute assays revealed concentration-dependent mortality, with 96-h LC50 values of 3.074 mg/L for BB and 1.991 mg/L for AT, indicating higher fish sensitivity. Behavioral impairments-reduced crawling and mucus secretion in BB, and erratic swimming, equilibrium loss, and opercular changes in AT-signaled early neurophysiological disruption. Chronic exposure (10 % and 20 % LC50) caused significant oxidative stress, tissue damage, and DNA fragmentation, corroborated by elevated tail length and tail moment in the comet assay. Molecular docking provided mechanistic support, revealing strong fluorene affinity for catalase and DNA polymerase in BB (-6.8 and -6.1 kcal/mol) versus DNA topoisomerase in AT (-6.2 kcal/mol). These interactions, dominated by π-π stacking and hydrophobic contacts, suggest catalytic inhibition and structural destabilization of antioxidant and genomic enzymes. Consequently, oxidative stress emerged as the primary toxicity pathway in BB, while replication stress and genotoxicity dominated in AT. Histopathological lesions-epithelial atrophy in BB and hepatocellular hypertrophy in AT-further reflected divergent metabolic responses. Collectively, the cross-species evidence highlights that even a structurally simple PAH such as fluorene exerts complex, multi-level effects through conserved molecular targets. These findings underscore species-specific vulnerabilities and demonstrate the ecological and regulatory importance of incorporating in silico-in vivo integration in aquatic PAH risk assessment.

The present study has investigated per- and poly-fluoroalkyl substances (PFAS) in the gill tissues of various fish species inhabiting different trophic levels within Eleyele Lake, a tropical freshwater lake in Nigeria. The mean concentrations of PFAS congeners were determined, and their trends and patterns were analyzed across different trophic species. The results revealed variations in congener abundance and species-specific patterns that was influenced by habitat and niche preferences. Multivariate associations using canonical-correlation analysis (CCA) revealed distinct trends in the relationships between gill concentrations of specific PFAS congeners and different trophic groups. The strongest congener relationships were observed in the pelagic omnivore (Oreochromic niloticus: ON) with positive associations for 4:2 FTS, 9CL-PF3ONS, PFTDA, MeFOSA and PFHxS. The differences in congener profiles for the two herbivorous fish (Sarotherodon melanotheron (SM) and Coptodon galilaeus (CG)) reflect possible divergence in microhabitat and niche preferences. Furthermore, the congener overlaps between the herbivore (CG), and benthic omnivore (Clarias gariepinus: ClG) indicate a possible niche and microhabitat overlap. Our study provides valuable insights into the congener dynamics of PFAS at Eleyele Lake. However, the dissimilarity and overlapping PFAS congener profile in fish gills reflects the interplay of species niche preference and microhabitat associations. The present study highlights the need for further research to assess ecological risks and develop effective PFAS management strategies.

In this study, we investigated the growth dynamics and otolith shape asymmetry of two fish species, Chrysichthys nigrodigitatus (CN) and Oreochromis niloticus (ON), within urbanized watersheds of the southern lagoon system, Nigeria. Using the von Bertalanffy growth model (VBGM), in addition to sediment metal concentration indices such as the average shale content, index of geoaccumulation (Igeo), contamination factor (CF), pollution load index (PLI), and potential ecological risk (PER) index, contamination levels were classified, and ecological risks were assessed. Notably, a lower growth potential (t0) was observed in CN at Ikorodu than at Epe, with similar trends for ON in the Epe during the dry season. Otolith asymmetry patterns, particularly in the CN at Ikorodu and ON in the Epe during the dry season, exhibited distinct ecological variations, indicating heightened stress levels at Ikorodu. Sediment analyses revealed moderate to strong contamination (Cd, Pb, Ni, and Cr) in both Lagos Lagoon (Ikorodu) and Epe Lagoon, with Ikorodu exhibiting notably high to moderate contamination levels according to the CF index. Elevated PLI values for Cd and Pb in Ikorodu, in addition to greater PER, indicated increased risk, with Cd posing a high risk (61.42%) and Pb posing a moderate risk (49.50%). Additionally, the reduced asymptotic length in the Epe during the dry season suggests that Chrysichthys nigrodigitatus is adaptable to seasonal variations, while divergent growth patterns in both areas indicate the existence of trade-off mechanisms in response to changing conditions. Habitat-specific otolith asymmetry and metal contamination underscore species adaptability, with wider stressor variability in Lagos than in Epe. Furthermore, multidimensional scaling analysis highlights the intricate relationship between otolith shape variables and environmental factors, emphasizing the need for tailored conservation efforts in urbanized watersheds.

Microplastic pollution presents a serious risk to marine ecosystems worldwide, with West Africa being especially susceptible. This study sought to identify the key factors driving microplastic dynamics in the region. Using NASA's Giovanni system, we analyzed environmental data from 2019 to 2024. Results showed uniform offshore air temperatures due to turbulence (25.22-45.62 K) with significant variations nearshore. Salinity levels remained largely stable (4 PSU) but slightly decreased in southern Nigeria. Surface wind speeds rose from 4.206-5.026 m/s in Nigeria to over 5.848 m/s off Mauritania, while eastward stress hotspots were prominent in Nigeria and from Sierra Leone to Senegal. Photosynthetically available radiation (PAR) beam values peaked off Mauritania and dipped from Nigeria to Sierra Leone, with the inverse pattern observed for diffuse PAR. Hotspots of high absorption, particulate backscattering, elevated aerosol optical depth, and remote sensing reflectance all pointed to substantial particulate matter concentrations. The Microplastic Vulnerability Index (MVI) identifies the coastal stretch from Nigeria to Guinea-Bissau as highly vulnerable to microplastic accumulation due to conditions that favor buildup. In contrast, moderate vulnerability was observed from Guinea-Bissau to Senegal and in Mauritania, where conditions were less extreme, such as higher offshore temperatures that could promote widespread microplastic suspension and cooler nearshore temperatures that favor sedimentation. Increased turbulence and temperatures in coastal areas of Senegal and Mauritania may enhance microplastic transport and impact marine life. In Nigeria, stable coastal conditions-characterized by consistent temperatures, low turbulence, and uniform salinity-may lead to increased persistence and accumulation of microplastics in sensitive habitats like mangroves and coral reefs. These findings highlight the need for region-specific management strategies to address microplastic pollution and effectively protect marine ecosystems.

Polycyclic aromatic hydrocarbons (PAHs), including acenaphthene, pose a significant threat to aquatic ecosystems by harming vital organisms such as benthic invertebrates. This study evaluated the impact of environmentally relevant concentrations of acenaphthene on Tubifex tubifex, focusing on sublethal acute toxicity and subchronic biomarker responses. Key biomarkers assessed included histopathological changes and the modulation of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and malondialdehyde (MDA). Additionally, the study examined structure–activity relationships and species sensitivity distribution (SSD). Concentrations exceeding the solubility threshold of acenaphthene (3.9 mg/L) triggered distinct, concentration-dependent behavioral responses in Tubifex tubifex, such as clumping, mucus secretion, and body wrinkling. Prolonged exposure exacerbated these behavioral dysfunctions, while subchronic exposure resulted in significant histopathological alterations, including epithelial hyperplasia, inflammation, edema, fibrosis, and degenerative changes. The edematic appearance of the body wall suggested a potential immune response to exposure. Furthermore, increased activities of CAT, SOD, and GST indicated oxidative stress in the worms. The study found a 1.5-fold increase in CAT and GST activity, a fivefold increase in SOD, and a striking 100-fold increase in MDA levels compared to controls, signifying an overwhelmed antioxidant defense system and potential cellular disruption. The SSD curve revealed hazard concentrations (HC50 and HC90), indicating that Tubifex tubifex exhibited lower sensitivity to acenaphthene compared to other taxa. In silico analysis and read-across models confirmed the potential of acenaphthene to induce significant oxidative stress upon exposure. The correlation between biomarker responses and structure–activity relationship analysis highlighted the aromatic nature of acenaphthene as a key factor in generating reactive metabolites, inhibiting antioxidant enzymes, and promoting redox cycling, ultimately contributing to adverse outcomes. These findings, coupled with behavioral responses and SSD curve inferences, underscore the importance of the solubility threshold of acenaphthene as a critical benchmark for evaluating its ecological impact in aquatic environments.

AbstractThe world's 1.4 million lakes (≥10 ha) provide many ecosystem services that are essential for human well‐being; however, only if their health status is good. Here, we reviewed common lake health issues and classified them using a simple human health‐based approach to outline that lakes are living systems that are in need of oxygen, clean water and a balanced energy and nutrient supply. The main reason for adopting some of the human health terminology for the lake health classification is to increase the awareness and understanding of global lake health issues. We show that lakes are exposed to various anthropogenic stressors which can result in many lake health issues, ranging from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning. Of particular concern for human well‐being is the widespread lake drying, which is a severe circulatory issue with many cascading effects on lake health. We estimated that ∼115,000 lakes evaporate twice as much water as they gain from direct precipitation, making them vulnerable to potential drying if inflowing waters follow the drying trend, putting more than 153 million people at risk who live in close vicinity to those lakes. Where lake health issues remain untreated, essential ecosystem services will decline or even vanish, posing a threat to the well‐being of millions of people. We recommend coordinated multisectoral and multidisciplinary prevention and treatment strategies, which need to include a follow‐up of the progress and an assessment of the resilience of lakes to intensifying threats. Priority should be given to implementing sewage water treatment, mitigating climate change, counteracting introductions of non‐native species to lakes and decreasing uncontrolled anthropogenic releases of chemicals into the hydro‐, bio‐, and atmosphere.

Lakes as essential ecosystems for diverse life forms, including humans, have suffered altered morphology with adverse effects on biodiversity including amphibians and amphibious species. Thus, it is imperative for effective conservation strategies to simultaneously consider lake morphology, landscape variables, and the role of keystone species as ecosystem engineers for biodiversity preservation. Keystone species, particularly birds and large-bodied predators, i.e., crocodylians, play a critical role in maintaining the health of lake ecosystems as ecosystem engineers, bringing about large-scale changes in lake morphology and hydrology that determine the abundance and survival of other species in the ecosystem. Conservation strategies should, therefore, prioritize the protection of these keystone species and their habitats. To balance the needs of human society with the protection of lake ecosystems and their biodiversity, conservation practices must involve stakeholder engagement, including government agencies, local communities, traditional ecological knowledge, and scientists. A multidisciplinary approach, incorporating ecological, hydrological, and social factors, is considered necessary for effective lake conservation. This approach will encompass the preservation of lake biodiversity and consider important variables such as lake morphology, landscape variables, and the role of keystone species as ecosystem engineers in providing insights for strategic conservation practices.

We have investigated the occurrence, distribution, and biomagnification of per- and polyfluoroalkyl substances (PFAS) in two tropical lakes (Asejire and Eleyele) of Southwestern Nigeria, with contrasting urban intensities. Over an 8-month period, we sampled sediment and fish species (Clarias gariepinus: CIG; Oreochromis niloticus: ON; Coptodon guineensis: CG; Sarotherodon melanotheron: SM) across trophic levels, and analyzed various PFAS congeners, in addition to a select group of toxicological responses. While herbivores (SM) and benthic omnivores (CIG) at Asejire exhibited elevated levels of PFBS and PFOS, the pelagic omnivores (ON) showed a dominance of PFOS, PFDA, PFHxDA and EtFOSE in the muscle. At the Eleyele urban lake, PFAS patterns was dominated by PFBS, EtFOSE, PFPeS, PFOcDA and PFOS in the herbivores (SM, CG), EtFOSE, PFOS and PFBS in the pelagic omnivore (ON) and benthic omnivore (ClG). The estimated biomagnification factor (BMF) analysis for both lakes indicated trophic level increase of PFOS, PFUnA and PFDA at the suburban lake, while PFOS and EtFOSE biomagnified at the urban lake. We detected the occurrence of diSAMPAP and 9CL-PF3ONS, novel compounds not commonly reported, in PFAS studies at both lakes. The studied toxicological responses varied across trophic groups in both lakes with probable modulations by environmental conditions, trophic structure, and relative PFAS exposures in the lakes. The present study documents, for the first time in Nigeria, or any other African country, the role of urbanization on contaminant load into the environment and their implications for contaminant dynamics within the ecosystem and for aquatic food safety.

This study examined the multifaceted impacts of fluorene exposure on Tubifex tubifex, encompassing acute (survival analysis and behavioral responses) and subchronic exposure regimens (antioxidant enzyme response and histopathology), molecular docking studies, and generalized read-across analysis. Survival analysis revealed concentration-dependent increases in toxicity over varying time intervals, with LC50 values decreasing from 30.072 mg/L at 24 h to 12.365 mg/L at 96 h, emphasizing the time-sensitive and concentration-responsive nature of the stressor. Behavioral responses were both concentration- and duration-dependent. While Erratic Movement and Clumping Tendency exhibited earlier responses (within 24 h) at lower concentrations, the wrinkling effect and mucus secretion) exhibited delayed onset, suggesting intricate regulatory mechanisms underlying adaptability to environmental challenges; moreover, the wrinkling effect was consistently induced at higher concentrations, indicating greater sensitivity to the toxic effects of fluorene. With sublethal environmentally relevant concentrations-1.24 mg/l and 2.47 mg/L i.e., 10% and 20% 96 h, respectively-the antioxidant enzyme response (i.e., upregulation of SOD, CAT, and GST) with increasing fluorene concentration, revealing a nonlinear, hormetic response, suggested adaptive protection at lower doses but inhibition at higher concentrations. Histopathological examination indicated that higher fluorene concentrations caused cellular proliferation, inflammation, and severe tissue damage in the digestive tract and body wall. Molecular docking studies demonstrated robust interactions between fluorene and major stress biomarker enzymes, disrupting their functions and inducing oxidative stress. Interactions with cytochrome c oxidase suggested interference with cellular energy production. Generalized Read-Across (GenRA) analysis unveiled shared toxicity mechanisms among fluorene and its analogs, involving the formation of reactive epoxides and the influence of cytochrome P450 enzymes. The diverse functional groups of these analogs, particularly chlorine-containing compounds, were implicated in toxicity through lipid peroxidation and membrane damage. Adverse outcome pathways and broader consequences for aquatic ecosystem health are discussed.

Introduction: Estrogenic chemicals in aquatic environments impact fish reproductive health, with vitellogenin protein levels serving as a crucial biomarker for xenoestrogen exposure. Limited knowledge exists on estrogenic effects in tropical environments, prompting an investigation into the influence of environmental estrogens on Chrysichthys nigrodigitatus in Lagos and Epe lagoons.Methods: A total of 195 fish samples underwent analysis for vitellogenin protein, sex hormones (testosterone and 17 β-estradiol), and gonad pathology in effluent-receiving areas of the specified lagoons.Results: Gonadal alterations were observed in male and female fish, including empty seminiferous tubules and distorted ovaries. Intersex occurred in 3.81% of Lagos and 3.33% of Epe. Testosterone levels were generally higher in females and males from both lagoons, while E2 levels were higher in females from both lagoons, with Lagos showing higher levels than Epe. Vtg levels were higher in males than females in Lagos samples but showed no significant difference in Epe samples.Discussion: Contaminant analysis revealed similar trends in metals (Hg, As, Cr) and phthalates (DEHP, DBP, DEP) in both sexes in the Epe population. Multivariate depictions from the PCA showed sex-specific patterns of metal uptake (Cd) in male fishes at the Lagos Lagoon. The positive association between higher pH loadings and metal and DBP levels in sediment at the Lagos lagoon suggests the influence of higher alkalinity in lower bioavailability of contaminants.Conclusion: Endocrine disrupting effects were observed in male and female Chrysichthys nigrodigitatus in Lagos and Epe lagoons populations, with notable differences in hormone and contaminant concentrations between the two lagoon systems. Identification of specific contaminants and their spatial and temporal trends can inform targeted management and remediation efforts to protect and restore these valuable aquatic ecosystems.

This study aims to understand the effects of freshwater acidification, driven by industrial runoff, agricultural activities, and atmospheric deposition, on the freshwater mollusk Bellamya bengalensis. By systematically investigating the impact of two common carboxylic acids, acetic acid (AA) and benzoic acid (BA), this research employed diverse toxicological, pathological, and ecological assessments. We explored survival predictions through the generic unified threshold model of survival (GUTS-SD), examined oxidative stress responses, and investigated hepatopancreatic alterations. In the experimental design, Bellamya bengalensis were subjected to environmentally relevant sublethal concentrations (10%, 20% LC50) of AA (39.77 and 79.54 mg/l) and BA (31.41 and 62.82 mg/l) over a 28-day period. Acute toxicity tests revealed increased LC50 values, indicating heightened toxicity with prolonged exposure, particularly due to the greater potency of benzoic acid compared to acetic acid. The GUTS-SD model provided accurate predictions of time-specific effects on populations, presenting long-term exposure (100 days) LC50 values for AA (263.7 mg/l) and BA (330.9 mg/l). Sequentially, the integrated biomarker response (IBR) analysis across study intervals highlighted the 28-day interval as the most sensitive, with GST emerging as the most responsive enzyme to oxidative stress induced by AA and BA. Histopathological evaluations and ultrastructural assessments of the hepatopancreas revealed severe alterations, such as necrosis and vacuolation, particularly pronounced after BA exposure. These findings underscore the potential impacts on the health and survival of Bellamya bengalensis, contributing to an enhanced understanding of carboxylic acid toxicity and emphasizing the need for proactive measures to mitigate the impacts of acidification on aquatic ecosystems. The observed effects on Bellamya bengalensis have broader ecological implications, highlighting the critical importance of effective management and conservation strategies in the face of ongoing environmental challenges.

Global freshwater acidification, accelerated by rising pCO2, remains a critical ecological concern. Despite the prevalence of carboxylic acids like acetic acid (AA) and benzoic acid (BA) in freshwater, their potential to exacerbate acidification and impact biota is not fully understood. In this study, we examined behavioural disruptions during acute exposures (96 h) and operculum ultrastructure changes during chronic exposures (28 days) to ecologically-relevant concentrations of AA (39.7, 79.5, and 99.4 mg/L) and BA (31.4, 62.8, and 78.5 mg/L) in Bellamya bengalensis. Acute exposures revealed significant behavioural disruption, including reduced activity and impaired escape behaviour. Chronic exposures led to ultrastructural defects in the operculum, with more pronounced effects in BA-exposed groups. Acidification scenarios appeared to impact calcium carbonate crystal formation, compromising opercula structure. Our study underscores the importance of understanding both acute and chronic effects of freshwater acidification on molluscan species, emphasising the need for further research into the underlying mechanisms and thresholds of acidification tolerance.

We investigated the potential ecological risks and harm to aquatic organisms posed by anionic surfactants such as α-olefin sulfonate (AOS), which are commonly found in industrial and consumer products, including detergents. This study assessed acute (96-h) and subchronic (14-day) responses using antioxidant activity, protein levels, and histopathological changes in Tubifex tubifex exposed to different AOS concentrations (10

This study aimed to predict the dynamics of per- and polyfluoroalkyl substance (PFAS) contamination and ecological vulnerability within coastal regions of Africa utilizing time-averaged remote-sensed data patterns from 2020 to 2023. The analysis identified PFAS contamination hotspots along the coast of Africa, particularly in western Africa around Nigeria and in areas spanning Equatorial Guinea and Guinea-Bissau, with risk influenced by eastward wind patterns, overland runoff, and elevated aerosol optical depth (AOD) values. Regional trends indicated that variations in solar energy absorption and surface air temperature could influence PFAS dynamics in North Africa, South Africa, East Africa, and West Africa. In North Africa, intermediate overland runoff and lower sea-surface temperatures were observed. In South Africa, there were intermediate runoff levels and warmer sea-surface temperatures. East Africa experienced intermediate runoff as well. In West Africa, there was increased susceptibility to high overland runoff and aerosol-related PFAS contamination. From the weighted vulnerability index, significant disparities in environmental conditions across African coastal regions revealed that North Africa had relatively lower vulnerability, while West Africa had the highest susceptibility to per- and polyfluoroalkyl substance (PFAS) contamination. This study emphasizes the necessity for region-specific vulnerability index models and targeted mitigation strategies to address diverse ecological and health risks from PFAS contamination along the African coast. Regional and international collaboration, spearheaded by organizations such as the AU and ECOWAS, is essential, with tailored policies aligned with the SDGs, Agenda 2063, and NEPAD crucial for effective environmental management, urging policymakers to prioritize cooperation and resource sharing for comprehensive sustainability goals.

This study explored the morpho-functional variations in the otoliths of Oreochromis niloticus (ON) and Chrysichthys nigrodigitatus (CN) across the Ikorodu (IKL) and Epe (EPL) regions in Nigeria's southern coastal lagoon system, with monthly sampling over twelve months. Digitized otoliths provided shape descriptors, and bathymetric analysis was conducted using the depth invariance index (DII). Remotely sensed reflectance (RSR) at 469nm, 531nm, and 555nm assessed habitat productivity. Morpho-functional variations were evaluated using discriminant analysis (DA) and principal component analysis (PCA). Bathymetric analysis revealed that EPL has a deeper and more heterogeneous substratum than IKL. Additionally, Epe exhibited consistently higher RSR values than IKL. Sediment analysis showed higher clay and silt percentages in IKL and increased coarse sand in EPL, indicating distinct terrains. DA accuracy was high (ON: 92.0%, CN: 90.8% in cross-validation), highlighting variables such as area and circumference for ON and area, circularity, and compactness for CN. DA emphasized ellipticity, rectangularity, and roundness for ON, and form factor, compactness, circularity, and aspect ratio for CN. Higher reflectance values at EPL than at IKL indicate distinct ecological characteristics, with greater nutrient cycling and trophic productivity at EPL. Sediment analysis revealed distinct ecological heterogeneity and hydrological effects, with finer sediments in IKL indicating calmer conditions and EPL exhibiting higher energy conditions. Visualizing normal curve distributions for otolith shape descriptors in ON and CN populations revealed skewness patterns indicative of divergent adaptive features, possibly associated with habitat heterogeneity and productivity. The key otolith variables identified by DA and PCA suggest relative ecological opportunity and underscore the intricate relationships between otolith morphology and habitat variables (heterogeneity, productivity, sediment profile) in Nigeria's tropical southern lagoon system.