Effects of heavy metals on fish physiology - A review

Toxicity of water-soluble polymers polyethylene glycol and polyvinyl alcohol for fish and frog embryos

Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the European Union in the early 2000s. The accumulation of PCPs in the aquatic environment and their effects on non-target species make it necessary to find new, less harmful, substances. Polyethylene glycol (PEGs) and polyvinyl alcohol (PVAs) are two polymers that have increased their presence in the composition of PCPs in recent years, but little is known about the effect of their accumulation in the environment on non-target species. Through embryotoxicity tests on two common models of aquatic organisms (Danio rerio and Xenopus laevis), this work aims to increase the knowledge of PEGs and PVAs' effects on non-target species. Animals were exposed to the pollutant for 96 h. The main embryotoxicity endpoint (mortality, hatching, malformations, heartbeat rate) was recorded every 24 h. The most significant results were hatching delay in Danio rerio exposed to both chemicals, in malformations (oedema, body malformations, changes in pigmentation and deformations of spine and tail) in D. rerio and X. laevis and significant change in the heartbeat rate (decrease or increase in the rate) in both animals for all chemicals tested.

Combined toxicity of polyvinyl chloride microplastics and copper to marine jacopever (Sebastes schlegelii)

Marine organisms commonly encounter co-stress resulting from the coexistence of microplastics (MPs) and heavy metals pollution in marine environments. Nevertheless, the combined effects and toxicity mechanisms of MPs and heavy metals on marine organisms remain unclear. This study integrated growth, physiological, morphological, and biochemical markers to assess the individual and combined toxicity of polyvinyl chloride MPs (PVC MPs, 1 × 104 particles/L) and copper (Cu, 200 μg/L) on marine jacopever (Sebastes schlegelii). The results revealed that co-exposure to MPs and Cu had a more detrimental impact on jacopever compared to the single-exposure groups, as evidenced by the enhanced growth inhibition, respiratory stress, and hepatotoxicity. This phenomenon may be attributed to PVC MPs accelerating the accumulation of Cu in jacopever liver. Therefore, peroxidation damage occurred in the co-exposed liver and may result in liver dysfunction. These findings contribute valuable insights into the risks associated with the coexistence of MPs and heavy metal pollution in marine ecosystems.

Risk assessment of heavy metals and total petroleum hydrocarbons (TPHs) in coastal sediments of commercial and industrial areas of Hormozgan province, Iran

The significant increase in the pollution of heavy metals and organic pollutants, their stable nature, and their high toxicity are gradually becoming a global crisis. In a recent study, a comprehensive assessment of the spatial distribution of heavy metals and total petroleum hydrocarbons (TPHs), as well as an assessment of their ecological risks in the sediments of 32 stations located in commercial and industrial areas (Mainly focusing on petrochemical and power industries, desalination plants and transit Ports) of Hormozgan province (East and West of Jask, Bandar Abbas, Qeshm, and Bandar Lengeh) was performed during 2021-2022. The sediment samples were digested with HNO3, HCl and HF solvents. The concentration of heavy metals was determined with furnace and flame systems of atomic absorption spectrometer. The concentration of heavy metals showed significant spatial changes between stations. The ecological assessment indices between the regions indicated that the stations located in Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan had a higher intensity of pollution than other places and significant risks of pollution, especially in terms of Cr and Ni. The average contamination degree (CD) (14.89), modified contamination degree (MCD) (2.48), pollution load index (PLI) (2.32), and potential ecological risk index (PERI) (100.30) showed the sediments in the area of Shahid Bahonar Port, Suru beach and Khor gorsouzuan, experience significant to high levels of pollution, especially Cr and Ni. Using contamination factor (CF) and Geoaccumulation index (Igeo), Cr was considered the most dangerous metal in the studied areas. Based on the global classification of marine sediment quality for the concentrations of TPHs, the sediments of the studied stations were classified as non-polluted to low pollution. In all regions, indices of the PELq (General toxicity) and CF (Contamination factor) were much lower than 0.1 and 1 respectively, showing the absence of adverse biological effects caused by TPHs in sediments. It is necessary to consider comprehensive and impressive strategies to control and reduce pollution of heavy metals, especially in the areas of Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan, so that the sources of this pollution are required to be identified and managed.

Histopathology and changes in the expression of metallothioneins, heat shock proteins and inducible nitric oxide synthase in Prochilodus costatus from a neotropical river contaminated by heavy metals

The most recent dam rupture in Brazil released tons of mining tailings into the upper course of the Paraopeba River, affecting this river in an unprecedented way. The present study aimed to evaluate the influence of heavy metals on Prochilodus costatus, an important commercial species in Brazil, four years after the dam colapse. To this end, biomarkers of heavy metals, oxidative stress, and environmental stress were analyzed, and histological analyses of target organs were performed. The results demonstrated critical contamination of fish from the Paraopeba River. Increased expression of Metallothioneins - MTs, Heat Shock Protein - HSP70, and inducible nitric oxide synthase - iNOS, as well as greater rates of histological changes in the liver, spleen, and gonads, were observed in P. costatus. These findings demonstrate that, despite past contamination, the metals present in mining tailings have significantly increased the contamination of the Paraopeba River basin.

Bioaccumulation of Organic and Inorganic Pollutants in Fish from Thermaikos Gulf: Preliminary Human Health Risk Assessment Assisted by a Computational Approach

The monitoring of contaminants in fish species is pivotal for fishes' health and reproduction, as well as for human health. In the specific work, three major categories of contaminants, pesticides, pharmaceuticals, and macro and trace elements, were investigated in two major fish species, Dicentrarchus labrax and Solea solea, collected from Thermaikos Gulf, in Greece. To achieve this goal, three analytical methods using LC-MS/MS, GC-MS/MS, and ICP-MS were developed, validated, and applied to the collected fish samples. The results indicated a very low prevalence of caffeine and acetaminophen, both not exceeding 3.8 μg/kg fish. Similarly, thiabendazole, cypermethrin, and tricyclazole (pesticides) were found in a concentration range of 0.9 to 13.7 μg/kg fish, while in one D. labrax sample, traces of the metabolite of organochlorine pesticide DDT, o,p'-DDE were detected. Al, Mn, Fe, Zn, and Sr were the predominant trace elements in a concentration range of 500-20,000 μg/kg fish. Macro elements levels varied from 280 to 5405 mg/kg fish. Health risk assessment did not unveil an unacceptable risk for the human health of adults, apart from one sample presenting Hg above the regulatory levels. On the contrary, for children, the calculated hazard quotient values for Hg in all cases and for two As detections were higher than the threshold value of 1, indicating a potential risk.

Applications of engineered biochar in remediation of heavy metal(loid)s pollution from wastewater: Current perspectives toward sustainable development goals

Environmental pollution of heavy metal(loid)s (HMs) caused adverse impacts, has become one of the emerging concerns and challenges worldwide. Metal(loid)s can pose significant threats to living organisms even when present in trace levels within environmental matrices. Extended exposure to these substances can lead to adverse health consequences in humans. Removing HM-contaminated water and moving toward sustainable development goals (SDGs) is critical. In this mission, biochar has recently gained attention in the environmental sector as a green and alternative material for wastewater removal. This work provides a comprehensive analysis of the remediation of typical HMs by biochars, associated with an understanding of remediation mechanisms, and gives practical solutions for ecologically sustainable. Applying engineered biochar in various fields, especially with nanoscale biochar-aided wastewater treatment approaches, can eliminate hazardous metal(loid) contaminants, highlighting an environmentally friendly and low-cost method. Surface modification of engineered biochar with nanomaterials is a potential strategy that positively influences its sorption capacity to remove contaminants. The research findings highlighted the biochars' ability to adsorb HM ions based on increased specific surface area (SSA), heightened porosity, and forming inner-sphere complexes with oxygen-rich groups. Utilizing biochar modification emerged as a viable approach for addressing lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), and chromium (Cr) pollution in aqueous environments. Most biochars investigated demonstrated a removal efficiency >90 % (Cd, As, Hg) and can reach an impressive 99 % (Pb and Cr). Furthermore, biochar and advanced engineered applications are also considered alternative solutions based on the circular economy.

Bioaccumulation and health risk assessment of trace elements in Tilapia (Oreochromis mossambicus) from selected inland water bodies

The presence of toxic trace elements (TEs) has resulted in a worldwide deterioration in freshwater ecosystem quality. This study aimed to analyze the distribution of TEs, including chromium (Cr), nickel (Ni), arsenic (As), mercury (Hg), cadmium (Cd), and lead (Pb), in water, sediment, and organs of Tilapia (Oreochromis mossambicus) collected from selected inland water bodies in Tamil Nadu, India. The water samples exhibited a range of concentrations for TEs: Cr varied from 0.014 to 5.193 µg/L, Ni ranged from 0.283 to 11.133 µg/L, As ranged from 0.503 to 1.519 µg/L, Cd from 0.001 to 0.616 µg/L, and Pb ranged from non-detectable (ND) to 6.103 µg/L. The concentrations of TEs in sediment were found to vary within the following ranges: 5.259 to 32.621 mg/kg for Cr, 1.932 to 30.487 mg/kg for Ni, 0.129 to 0.563 mg/kg for As, 0.003 to 0.011 mg/kg for Cd, ND to 0.003 mg/kg for Hg, and 0.404 to 1.575 mg/kg for Pb. The study found that the accumulation pattern of TE in fishes across all selected areas was liver > bone > gill > muscle. The organs had TE concentrations of Cr (ND-0.769 mg/kg), Ni (ND-1.053 mg/kg), As (0.002-0.080 mg/kg), Pb (ND-0.411 mg/kg), and Hg (ND-0.067 mg/kg), which was below the maximum residual limit prescribed by EC and FSSAI. The bioconcentration factor (BCF) of TEs exhibited a greater magnitude in comparison with the biota-sediment accumulation factor due to the higher concentration of TEs in fish and lower level in water. The assessment of both carcinogenic and non-carcinogenic risks suggests that the consumption of Tilapia from the study region does not pose any significant risks.

Synthesis of gamma irradiated acrylic acid-grafted-sawdust (SD-g-AAc) for trivalent chromium adsorption from aqueous solution

Water pollution caused by chromium released from tannery is a serious concern to the environment and public health. Chromium removal from tannery effluent is a crying need before discharging to the surface water. In this study, acrylic acid-grafted sawdust was prepared by Tectona grandis sawdust grafting with acrylic acid employing gamma irradiation in the presence of air and Mohr's salt. It was treated with NaOH and the characterization of surface morphology and functional groups of modified sawdust was studied by SEM and FTIR.. The effects of solution pH, adsorbent dosage, adsorption time, and initial Cr(III) ion concentration were investigated by batch sorption studies. The process was found to be pH, temperature and concentration dependent. Langmuir and Freundlich isotherms were applied to realize the adsorption process in depth, and it was found that the Langmuir isotherm model fitted well with experimental data (R2 value of 0.983). The maximum monolayer adsorption capacity of acrylic acid-grafted sawdust for Cr(III) from aquous solution was found to be 21.55 mg g-1 at 25 °C. Pseudo-first-order and pseudo-second-order kinetic models were employed to analyze the kinetics of the process, and it was found that the experimental process followed the pseudo-second-order kinetic model, i.e. chemisorption. This study revealed that acrylic acid-grafted sawdust has a decent potential for the removal of Cr(III) from tannery effluents.

Potentially toxic trace elements in the muscle of coastal South American fish: Implications for human consumption and health risk assessment

Micropogonias furnieri and Urophycis brasiliensis are two coastal demersal fish species distributed in the southwestern Atlantic Ocean. Considering that many coastal areas in the southwestern Atlantic Ocean suffer from anthropogenic pressure, the aim of this study was to assess the level of potentially toxic trace elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, Sr, V and Zn) in the muscle of coastal species, and evaluated the human health risk related to the consumption of muscle. Mercury, inorganic As (Asi), V, and Se showed a higher contribution to the total THQ. Considering two possible scenarios, Asi represents 1 % or 5 % of the total As, the total THQ was <1 for general population and of some health concerns for fishermen population (Total THQ > 1; 5 % Asi). Consequently these results show the importance of quantifying As species in muscle to generate more reliable risk estimates for human health.

Tissue Accumulation, Cytotoxicity, Oxidative Stress, and Immunotoxicity in African Catfish, Clarias gariepinus Exposed to Sublethal Concentrations of Hexavalent Chromium

Hexavalent chromium (Cr6+) is one of the stable oxidation states of chromium that has been reported to elicit various toxic effects in aquatic organisms. However, the mechanisms of Cr6+ toxicity are still poorly understood. Thus, the present study investigated the tissue accumulation, cytotoxic, oxidative stress, and immunotoxic effects of Cr6+ in juvenile Clarias gariepinus. The fish were exposed to waterborne Cr6+ concentrations (0, 0.42, 0.84, and 1.68 mg/L) for 28 days, after which they were sacrificed and various organs were harvested for the determination of Cr6+ levels. Other parameters that were indicators of oxidative stress, cytotoxicity, and immunotoxicity were measured. Cr6+ accumulated more in the kidney and liver of the exposed fish, especially at the highest concentration. The levels of lipid peroxidation and DNA fragmentation increased significantly in the exposed fish. The activities of superoxide dismutase and lactate dehydrogenase increased significantly in exposed fish compared to the control. The total white blood cells, lymphocytes, and neutrophils counts were significantly higher in the exposed fish compared to the control fish. The respiratory burst activity decreased significantly in the exposed fish while the myeloperoxidase content did not differ significantly. There were upregulations of TNF-α and HSP 70 while CYP II and MHC 2 were downregulated in the exposed fish. Also, exposure to Cr6+ resulted in various histopathological alterations in the architecture of the head kidney. The results indicate concentration-dependent toxic effects of Cr6+ in C. gariepinus. The study reveals the potentials of Cr6+ to accumulate in the different tissues of fish and caused cytotoxic, oxidative stress, and immunotoxic effects in the exposed fish.

Heavy metal levels and human health risk implications associated with fish consumption from the lower Omo river (Lotic) and Omo delta lake (Lentic), Ethiopia

This study is the first to determine the levels of heavy metals in commercially important fish species, namely Lates niloticus and Oreochromis niloticus and the potential human health risks associated with their consumption. A total of 120 fish samples were collected from the lower Omo river and Omo delta, with 60 samples from each water source. The fish tissue samples (liver and muscle) were analyzed using a flame atomic absorption spectrometer for nine heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn). The human health risk assessment tools used were the target hazard quotient (THQ), the hazard index (HI), and the target cancer risk (TCR). The mean levels of heavy metals detected in the liver and muscle of L. niloticus from the lower Omo river generally occurred in the order Fe > Zn > Pb> Cu > Mn> Cr > Co > Ni and Pb > Cu > Mn > Co > Ni, respectively. The mean levels of metals in the muscle and liver tissues of O. niloticus were in the order Fe > Pb > Zn > Mn > Cu > Cr > Co > Ni and Pb > Zn > Mn > Fe > Cu > Co > Ni, respectively. Similarly, the mean levels of heavy metals detected in the liver and muscle of L. niloticus from Omo delta occurred in the order Fe > Zn > Pb > Cu > Mn > Cr > Co > Ni and Fe > Pb > Zn > Mn > Cu > Co > Cr > Ni, respectively. The mean levels in the muscle and liver tissues of O. niloticus from the Omo delta were in the order Fe > Pb > Zn > Mn > Cu > Cr > Co > Ni and Pb > Fe > Zn > Mn > Co > Cu > Ni, respectively. The study revealed that the THQ values were below 1, indicating that consumption of L. niloticus and O. niloticus from the studied sites does not pose a potential non-carcinogenic health risk. Although the TCR values for Pb in this study were within the tolerable range, it's mean concentration in the muscle and liver tissues of both fish species from the two water bodies exceeded the permissible limit established by FAO/WHO. This is a warning sign for early intervention, and it emphasizes the need for regular monitoring of freshwater fish. Therefore, it is imperative to investigate the pollution levels and human health risks of heavy metals in fish tissues from lower Omo river and Omo delta for environmental and public health concerns.

Electrochemical Detection of Cd2+, Pb2+, Cu2+ and Hg2+ with Sensors Based on Carbonaceous Nanomaterials and Fe3O4 Nanoparticles

Two electrochemical sensors were developed in this study, with their preparations using two nanomaterials with remarkable properties, namely, carbon nanofibers (CNF) modified with Fe3O4 nanoparticles and multilayer carbon nanotubes (MWCNT) modified with Fe3O4 nanoparticles. The modified screen-printed electrodes (SPE) were thus named SPE/Fe3O4-CNF and SPE/Fe3O4-MWCNT and were used for the simultaneous detection of heavy metals (Cd2+, Pb2+, Cu2+ and Hg2+). The sensors have been spectrometrically and electrochemically characterized. The limits of detection of the SPE/Fe3O4-CNF sensor were 0.0615 μM, 0.0154 μM, 0.0320 μM and 0.0148 μM for Cd2+, Pb2+, Cu2+ and Hg2+, respectively, and 0.2719 μM, 0.3187 μM, 1.0436 μM and 0.9076 μM in the case of the SPE/ Fe3O4-MWCNT sensor (following optimization of the working parameters). Due to the modifying material, the results showed superior performance for the SPE/Fe3O4-CNF sensor, with extended linearity ranges and detection limits in the nanomolar range, compared to those of the SPE/Fe3O4-MWCNT sensor. For the quantification of heavy metal ions Cd2+, Pb2+, Cu2+ and Hg2+ with the SPE/Fe3O4-CNF sensor from real samples, the standard addition method was used because the values obtained for the recovery tests were good. The analysis of surface water samples from the Danube River has shown that the obtained values are significantly lower than the maximum limits allowed according to the quality standards specified by the United States Environmental Protection Agency (USEPA) and those of the World Health Organization (WHO). This research provides a complementary method based on electrochemical sensors for in situ monitoring of surface water quality, representing a useful tool in environmental studies.

Mitigation of haemato-genotoxic and stress response effects in Cyprinus carpio via silymarin dietary supplementation following deltamethrin exposure

The study examined the potential of Silymarin, a blend of bioactive flavonolignans extracted from the milk thistle Silybum marianum, to mitigate Deltamethrin-induced toxicity in the blood of Cyprinus carpio. Fish were exposed to Deltamethrin (0.66 μg/L), the plant extract, or a combination of both for a duration of thirty days. Various parameters, including serum biochemical markers, erythrocytic abnormalities, and genotoxicity endpoints, were assessed. Results indicated a significant (p < 0.05) increase in the levels of AST, ALT, ALP, blood urea nitrogen, creatinine, glucose, cholesterol, and TLC in the fish exposed to the pesticide. Conversely, total protein, TEC, and Hb showed a notable decrease. There was also a notable rise in micronuclei and erythrocytic abnormalities such as acanthocytes, microcytes, and notched cells. Under ultrastructural examination, phenotypic deformities like spherocytosis, discocytes, and clumped erythrocytes were observed. However, dietary supplementation of silymarin (1 g/kg) significantly restored the biochemical, genetic, and cellular parameters, resembling those of the control group. This suggests the potential of this plant extract in protecting the common carp, Cyprinus carpio, from Deltamethrin-induced damage by scavenging free radicals and reducing DNA oxidative stress.

Toxicity Evaluation, Oxidative, and Immune Responses of Mercury on Nile Tilapia: Modulatory Role of Dietary Nannochloropsis oculata

The current study evaluated the potential ameliorative effect of a dietary immune modulator, Nannochloropsis oculata microalga, on the mercuric chloride (HgCl2)-induced toxicity of Nile tilapia. Nile tilapia (45-50 g) were fed a control diet or exposed to ¼ LC50 of HgCl2 (0.3 mg/L) and fed on a medicated feed supplemented with N. oculata (5% and 10% (50 or 100 g/kg dry feed)) for 21 days. Growth and somatic indices, Hg2+ bioaccumulation in muscles, and serum acetylcholinesterase (AChE) activity were investigated. Antioxidant and stress-related gene expression analyses were carried out in gills and intestines. Histopathological examinations of gills and intestines were performed to monitor the traits associated with Hg2+ toxicity or refer to detoxification. Hg2+ toxicity led to significant musculature bioaccumulation, inhibited AChE activity, downregulated genes related to antioxidants and stress, and elicited histopathological changes in the gills and intestine. Supplementation with N. oculata at 10% was able to upregulate the anti-oxidative-related genes while downregulated the stress apoptotic genes in gills and intestines compared to the unexposed group. In addition, minor to no histopathological traits were detected in the gills and intestines of the N. oculata-supplemented diets. Our data showed the benefit of dietary N. oculata in suppressing Hg2+ toxicity, which might support its efficacy as therapeutic/preventive agent to overcome environmental heavy metal pollution in aquatic habitats.

Heavy metal and trace element concentrations in the blood of scalloped hammerhead sharks (Sphyrna lewini) from La Paz Bay, México

Sharks are particularly susceptible to bioaccumulation due to their life history characteristics and trophic position within marine ecosystems. Despite this, studies of bioaccumulation cover only a small proportion of extant species. In this study we report concentrations of trace elements and heavy metals in blood samples of Sphyrna lewini for the first time. We report high concentrations of several trace elements and heavy metals, with concentrations of some elements exceeding the limit determined safe for human consumption. High elemental concentrations may reflect biochemical differences between blood plasma and other tissues; however, they may also be symptomatic of high levels of exposure triggered by anthropogenic activities. We also provide evidence of elemental accumulation through ontogeny, the nature of which differs from that previously reported. Ultimately, this baseline study increases our understanding of interspecific and intraspecific variation in bioaccumulation and ecotoxicology in elasmobranchs which may prove important in ensuring adequate management.

Metal bioaccumulation and histological alterations in Oreochromis andersonii at Itezhi-tezhi Dam downstream of a mining area in the Central Province of Zambia

The Itezhi-tezhi Dam on the Kafue River in Zambia is a major capture fishery. However, the upstream reaches of the Kafue River receive effluents from copper mines. It was unclear whether fish health in the dam is adversely affected due to the mining effluents. We investigated the health status of fish in Itezhi-tezh Dam using a histology-based fish health assessment protocol with Oreochromis andersonii as a bioindicator. Fish were sampled in the Itezhi-tezh Dam and at a reference site further upstream on the Kafue River before it enters the mining region. Metal bioaccumulation, biometric indices and histological alterations in the gills, gonads, hearts, kidneys and livers were assessed. The findings revealed significantly higher copper and selenium sediment concentrations (p = 0.02843 and p = 0.02107 respectively), bioaccumulation of copper and selenium, and increased histological alterations in the gills, kidneys and livers of fish in the Itezhi-tezhi Dam.

Determination of potentially toxic elements bioaccumulated in the commercially important pelagic fish narrow-barred Spanish mackerel (Scomberomorus commerson)

Anthropogenic activities have increased the discharge of marine contaminants threatening marine life. Small gulfs, such as the Arabian Gulf, are vulnerable to accumulating potentially toxic elements in marine species due to slow water exchange. The concentration of 21 elements was determined in the tissues of Scomberomorus commerson from Umm Al Quwain (United Arab Emirates) and Bandar Abbas (Iran). Chromium, Copper, and Iron exceeded internationally established maximum permissible limits. Sites could not be distinguished based on Principle Component Analyses of elements. Elevated Cu and Cr in muscle are of concern to marine species as well as humans. Metal Pollution Index showed a significant difference between sites, with 20.34 % and 100 % of individuals suffering high metal toxicity and poor body conditions, respectively. The Arabian Gulf is experiencing an increase in discharge of industrial wastes. Implementation of strict policies to reduce discharge of toxic substances is required to protect marine organisms and humans.

Pollutant levels in the waters of the industrial area of North Aceh and Lhokseumawe Regency, Indonesia

This research was conducted from June to August 2023. Data and samples were collected using an exploratory survey method in four locations around the industrial area, namely PT. ASEAN Aceh Fertilizer and PT. Kertas Kraft Aceh in North Aceh Regency, while PT. Pupuk Iskandar Muda and PT. Harun NGL in Lhokseumawe Regency, Indonesia. Observations of physico-chemical parameters including measurements of salinity, bicarbonate, calcium, magnesium, nitrate, nitrite, orthophosphate, total alkalinity, and total ammonia were analyzed in the Laboratory of PT Intraco Agroindustri, Langkat Regency, North Sumatra, Indonesia. Microplastic analysis was carried out at the Faculty of Marine and Fisheries, Universitas Syiah Kuala, Banda Aceh, Indonesia. The biological parameters measured in this research include the chlorophyll concentration in the water locations observed. Based on the results of the analysis, it shows that the calcium, magnesium, orthophosphate content at the four research locations has exceeded the quality standards, while the nitrate content is only at PT. ASEAN Aceh Fertilizer and PT. Kertas Kraft Aceh that exceeds the quality standards. The bicarbonate, nitrite, salinity, total alkalinity, and total ammonia content at the four research locations were under normal conditions. The chlorophyll content in the four research locations was categorized as low fertility (oligotrophic). Based on the analysis, it also shows that the four research locations were contaminated with microplastics with a range of 2.78-5.49 particles/l.

Evaluating quaternium-15 effects on Mytilus galloprovincialis: New insights on physiological and cellular responses

Among personal care products, quaternium-15 is prominently featured as a preservative in items such as shampoos, soaps, shaving products, and cosmetics. The widespread use of these products in people's daily routines contributes to quaternium-15 release into aquatic ecosystems. In this context, the primary aim of the study was to assess the physiological and cellular responses of the digestive gland and gills in Mytilus galloprovincialis to quaternium-15 exposure. Cell viability and the ability of digestive gland cells to regulate their volume were evaluated. Additionally, the expression of the genes involved in oxidative stress response was assessed to further substantiate the compound's harmful effects. Results indicated a significant decrease in both the viability of digestive gland cells and their RVD (regulatory volume decrease) capacity when exposed to a hypotonic solution. Furthermore, impairment of digestive gland cell function was corroborated by the modulation of oxidative stress-related gene expression, including SOD, Cat, as well as Hsp70 and CYP4Y1. Similar gene expression alterations were observed in the gills, reflecting impaired functionality in this vital organ as well. In summary, the outcomes of the study provide conclusive evidence of the toxicity of quaternium-15. This underscores the urgent need to further investigate the toxicological effects of this contaminant on aquatic ecosystems and emphasises the necessity of limiting the use of products containing quaternium-15.

Assessing Metal Toxicity on Crustaceans in Aquatic Ecosystems: A Comprehensive Review

Residual concentrations of some trace elements and lightweight metals, including cadmium, copper, lead, mercury, silver, zinc, nickel, chromium, arsenic, gallium, indium, gold, cobalt, polonium, and thallium, are widely detected in aquatic ecosystems globally. Although their origin may be natural, human activities significantly elevate their environmental concentrations. Metals, renowned pollutants, threaten various organisms, particularly crustaceans. Due to their feeding habits and habitat, crustaceans are highly exposed to contaminants and are considered a crucial link in xenobiotic transfer through the food chain. Moreover, crustaceans absorb metals via their gills, crucial pathways for metal uptake in water. This review summarises the adverse effects of well-studied metals (Cd, Cu, Pb, Hg, Zn, Ni, Cr, As, Co) and synthesizes knowledge on the toxicity of less-studied metals (Ag, Ga, In, Au, Pl, Tl), their presence in waters, and impact on crustaceans. Bibliometric analysis underscores the significance of this topic. In general, the toxic effects of the examined metals can decrease survival rates by inducing oxidative stress, disrupting biochemical balance, causing histological damage, interfering with endocrine gland function, and inducing cytotoxicity. Metal exposure can also result in genotoxicity, reduced reproduction, and mortality. Despite current toxicity knowledge, there remains a research gap in this field, particularly concerning the toxicity of rare earth metals, presenting a potential future challenge.

Kinetic properties of glucose 6-phosphate dehydrogenase and inhibition effects of several metal ions on enzymatic activity in vitro and cells

Due to the non-degradable and persistent nature of metal ions in the environment, they are released into water bodies, where they accumulate in fish. In order to assess pollution in fish, the enzyme, glucose 6-phosphate dehydrogenase (G6PD), has been employed as a biomarker due to sensitivity to various ions. This study investigates the kinetic properties of the G6PD enzyme in yellow catfish (Pelteobagrus fulvidraco), and analyzes the effects of these metal ions on the G6PD enzyme activity in the ovarian cell line (CCO) of channel catfish (Ictalurus punctatus). IC50 values and inhibition types of G6PD were determined in the metal ions Cu2+, Al3+, Zn2+, and Cd2+. While, the inhibition types of Cu2+ and Al3+ were the competitive inhibition, Zn2+ and Cd2+ were the linear mixed noncompetitive and linear mixed competitive, respectively. In vitro experiments revealed an inverse correlation between G6PD activity and metal ion concentration, mRNA levels and enzyme activity of G6PD increased at the lower metal ion concentration and decreased at the higher concentration. Our findings suggest that metal ions pose a significant threat to G6PD activity even at low concentrations, potentially playing a crucial role in the toxicity mechanism of metal ion pollution. This information contributes to the development of a biomonitoring tool for assessing metal ion contamination in aquatic species.

Ecofriendly ratiometric colorimetric determination of mercury(II) ion in environmental water samples using gallic acid-capped gold nanoparticles

Today, the monitoring and determination of heavy metal pollutants in the environment is an essential requirement for the environmental and research communities. Mercury ion is one of the most hazardous heavy metals, and scientists are trying to develop new methods for its detection. In this study, a new colorimetric sensor based on aggregation gallic acid-capped gold nanoparticles (GA-AuNPs) for the determination of mercury ions in environmental water samples was presented. The green synthesized GA-AuNPs exhibited a sharp surface plasmon resonance peak at 515 nm. The addition of mercury ions changed the surface properties of GA-AuNPs, resulting in the formation of a new peak near 670 nm due to the aggregation of GA-AuNPs, and an obvious color change from red to purple occurred. Thus, mercury ions were detected based on the change in the absorbance ratio (A670/A515). The developed sensor can determine the mercury ions in the concentration range of 78.0 nM to 8.3 µM with a detection limit of 5.5 nM. Based on the Environmental Protection Agency (EPA) and the World Health Organization (WHO) reports, the amount of Hg2+ ions in fresh water should be between 10.0 and 30.0 nM. The results indicate that the developed sensor can detect and determine trace amounts of Hg2+ ions in environmental water samples.

Individual and combined impact of microplastics and lead acetate on the freshwater shrimp (Caridina fossarum): Biochemical effects and physiological responses

Microplastics and heavy metals pollution is recognised as a major problem affecting aquatic ecosystems. For this reason, this study aims to assess the toxicity of different concentrations of polyethylene microplastics (PE-MPs) (0.0, 500, and 1000 μg L-1) with a mean size of 15-25 μm and lead acetate Pb(C2H3O2)2 (0.0, 2.5, and 5 mg L-1), both individually and in combination, through the exposure of the freshwater grass shrimp, Caridinia fossarum for 15 days, focusing on microplastic interaction with co-occurring contaminants. After being exposed to both contaminants, either individually or in combination, significant alterations in numerous biochemical markers were observed. Specifically, exposure to lead acetate alone resulted in significant changes across ALP, AST, ALT, LDH, GGT, and BChE enzyme activity levels indicating hepatotoxicity and neurotoxicity. Also, Pb exposure led to alterations in total antioxidant capacity, MDA, total lipids, and glycogen contents, signalling the onset of oxidative stress. Exposure to PE-MPs alone led to changes in ALP, LDH, GGT, and BChE enzyme levels, and in MDA, total lipids, and glycogen samples' contents. Remarkably, the study observed increased bioaccumulation of lead acetate in samples treated with the combination, emphasizing the synergistic impact of PE-MPs on the toxicity of lead acetate. This synergy was also evident in AST and ALT enzyme activity levels and MDA contents. This underscores the necessity for measures to address both microplastic pollution and heavy metal contamination, taking into account the synergistic behaviour of MPs in the presence of concurrent contaminants.

Physicochemical assessment of industrial effluents of Kala Sanghian drain, Punjab, India

The discharge of industrial effluents has a significant impact on the Water Quality Index (WQI) of the water bodies and is a major source of contamination of groundwater. The present study investigated the physicochemical characteristics and scrutinized the pollution potential of the tannery, textile, and electroplating effluents uploading into the Kala Sanghian drain, located in Jalandhar, Punjab, India. In this study, 12 samples were collected from the four sites (leather complex drain (LD), leather complex outlet (LO), focal point drain (FD), and Bulandpur drain (BD)) of Kala Sanghian drain in the dry season. The result showed that the drain under consideration is very much contaminated and the water is not suitable for irrigation and agricultural purposes. Rather it has a bad impact on the health of local people, the physiology of aquatic organisms, and the soil quality of agricultural land nearby. The present study confirmed the water quality index was more than 100, indicating a highly contaminated drain and water is unfit for any use. The correlation analysis shows that there exists a positive correlation between TDS and temperature (r = 0.994), DO and pH (r = 0.808), BOD and temperature (r = 0.987), BOD and TDS (r = 0.978), EC and temperature (r = 0.963), EC and TDS (r = 0.954), and EC and BOD (r = 0.956). The principal component analysis (PCA) confirms that PC1 alone has more than 89% of the variance with high positive loading for TDS, temperature, EC, and BOD. The hierarchical cluster analysis (HCA) reflected two clusters where cluster 1 consists of pH, DO, temperature, and BOD of water while cluster 2 consists of TDS and EC of water. The PCA and HCA study of the data set confirms the high degree contribution of anthropogenic activities through the application of chemicals in agriculture, disposal of municipal waste, and industrial effluents in the deterioration of water quality. The results of the study will help to enhance the sustainable action plan for the management of industrial effluents in the studied area.

Assessing the disparity: comparative toxicity of Copper in zebrafish larvae exposes alarming consequences of permissible concentrations in Brazil

Copper (Cu) is a naturally occurring metal with essential micronutrient properties. However, this metal might also pose increased adverse environmental and health risks due to industrial and agricultural activities. In Brazil, the maximum allowable concentration of Cu in drinking water is 2 mg/L. Despite this standard, the impact of such concentrations on aquatic organisms remains unexplored. This study aimed to evaluate the toxicity of CuSO4 using larval zebrafish at environmentally relevant concentrations. Zebrafish (Danio rerio) larvae at 72 hr post-fertilization (hpf) were exposed to nominal CuSO4 concentrations ranging from 0.16 to 48 mg/L to determine the median lethal concentration (LC50), established at 8.4 mg/L. Subsequently, non-lethal concentrations of 0.16, 0.32, or 1.6 mg/L were selected for assessing CuSO4 -induced toxicity. Morphological parameters, including body length, yolk sac area, and swim bladder area, were adversely affected by CuSO4 exposure, particularly at 1.6 mg/L (3.31 mm ±0.1, 0.192 mm2 ±0.01, and 0.01 mm2 ±0.05, respectively). In contrast, the control group exhibited values of 3.62 mm ±0.09, 0.136 mm2 ±0.013, and 0.3 mm2 ±0.06, respectively. Behavioral assays demonstrated impairments in escape response and swimming capacity, accompanied by increased levels of reactive oxygen species (ROS) and lipid peroxidation. In addition, decreased levels of non-protein thiols and reduced cellular viability were noted. Data demonstrated that exposure to CuSO4 at similar concentrations as those permitted in Brazil for Cu adversely altered morphological, biochemical, and behavioral endpoints in zebrafish larvae. This study suggests that the permissible Cu concentrations in Brazil need to be reevaluated, given the potential enhanced adverse health risks of exposure to environmental metal contamination.

Enrichment and distribution of 3,6-dichlorocarbazole in red crucian carp (Carassius auratus) and its hepatotoxicity

Polyhalogenated carbazoles (PHCZs) are a class of organohalogen compounds where the hydrogen atom on the carbazole ring is replaced by a halogen atom. In recent years, PHCZs have drawn increasing concern due to their persistence, dioxin-like toxicity, bioaccumulation, potential ecological hazards and widespread occurrence in the environment. Current research on the enrichment and depuration of PHCZs in biological tissues and organs is insufficient, and the liver toxicity is unclear. Herein, to understand the enrichment and elimination of 3,6-DCCZ in fish tissues and organs as well as the hepatotoxicity, we exposed the red crucian carp to 20 and 100 μg/L of 3,6-DCCZ for 20 days followed by a depuration period of 10 days. The 3,6-DCCZ enrichment in each organ tissue was classified from high to low: brain > liver, intestine, gill > muscle. For depuration, 3,6-DCCZ was quickly excreted in the various organs of the red crucian carp; however, the liver depuration was slow, with the concentration of 3,6-DCCZ was maintained at 0.25-0.35 μg/g. 3,6-DCCZ exposure at both tested concentrations induced oxidative stress in red crucian carp, causing lipid peroxidation and DNA damage, as well as some histopathological changes in the liver, such as cell vacuolization, nucleus pyknosis, nucleus pleomorphism, no nucleus areas. Additionally, the 3,6-DCCZ exposure at higher concentration (100 μg/L) caused more serious damage and abnormal lipid metabolism in the red crucian carp liver.

Investigating seasonal metal impact on Stramonita haemastoma gastropod along the Algerian East Coast: Understanding through various pollution indicators

The main objective of this study was to assess the impact of environmental pollution on the gastropod Stramonita haemastoma by examining various physiological and biochemical parameters. Trace metal elements (TME) were measured in the snail's foot. Over a one-year period from 2013 to 2014, the study investigated the variations in reduced glutathione, malondialdehyde, metallothionein, glutathione S-transferase, acetylcholinesterase and catalase activities in the foot of the gastropod at three different sites. The results showed spatiotemporal fluctuations in biomarkers, physiological parameters and TME. This integrative approach, being the first of its kind in the region using S. haemastoma as a model organism, represents a means of environmental assessment accessible to all countries allowing the monitoring and conservation of coastal marine environments on a national and international scale and which could be used in marine biomonitoring programs to indicate the impact of pollution and assess the quality of the Algerian coastal marine environment.

Assessment of Essential and Potentially Toxic Elements in Water and Sediment and the Tissues of Sciaena deliciosa (Tschudi, 1846) from the Coast of Callao Bay, Peru

The lorna drum Sciaena deliciosa is a coastal demersal species and one of the underlying artisanal fisheries in some areas of Peru, and is also a source of protein for Peruvian coastal dwellers. The investigation addresses concern about the environmental impact on this fish species and the potential risks to human health through the consumption of contaminated seafood. This research endeavors to assess the concentration of potentially toxic and essential elements in the muscle and liver tissues of S. deliciosa, in addition to the presence thereof in water and sediment capture areas on the coast of Callao, Peru. The study revealed that, in water samples, Ag, Ni, and Zn exceed Peruvian standards, but were below international standards, and Ba, P, Se, and Sn exceed international standards. In the sediments, As, Cd, Pb, Fe, and Zn were above international standards. In the fish, S. delicious muscle demonstrated As, Hg, and Pb exceeding at least one international standard. In the liver, As, Hg, Pb, and Cu exceed international standards. The study approach increased accuracy in risk assessments, offering crucial insights into the interplay between heavy metal pollution, water quality, and animal health, informing risk management strategies. Future studies can explore the long-term effects of heavy metal exposure on different organisms and consider their cumulative impact on health.

A coumarin-based fluorescent probe for highly selective detection of hazardous mercury ions in living organisms

In recent years, heavy metal mercury (II) pollutants have caused serious harm to human health and ecosystems. It has become critical to develop simple and highly selective sensing solutions for monitoring mercury (II). In this work, we designed and developed a novel fluorescent probe Coa-SH using the Hg2+-induced chemical reaction as a sensing mechanism. The probe Coa-SH showed high selectivity for the detection of Hg2+ by desulfurization reactions in solution. The test strips prepared with this probe could be applied to detect mercury ions in aqueous solutions. In addition, the probe Coa-SH provided a tool to detect Hg2+ in living systems. In living cells and zebrafish, the probe turned on bright red fluorescent signals in the presence of mercury ions. Importantly, the probe Coa-SH enabled Hg2+ detection in plant onion roots. This work provides an effective method for monitoring mercury ions in the environment and in living organisms.

Trophic transfer and biomagnification potential of environmental contaminants (heavy metals) in aquatic ecosystems

Physical, chemical weathering and volcanic eruptions release heavy metals into soils and surface waters naturally. Contaminants from anthropogenic sources originated from industrial and municipality waste substantially modify and increase their contributions. They are then absorbed by fish gills, amphipod cuticles, and other sensitive organs of aquatic creatures. This article discusses the essences on the determination, potential and plausible factors of trophic transfer and biomagnification of environmental contaminants particularly heavy metals across aquatic ecosystem. In general, arsenic is found to be bio-diminished across food webs in freshwater ecosystem while it biomagnified in marine ecosystem of higher trophic level (tertiary consumer of predatory fish) and dilute its concentration from lower trophic level (from producer to bottom level of consumer, secondary and lastly to tertiary consumer (forage fish)). Early study for Cadmium shown that it has no potential for biomagnification while later studies prove that cadmium does magnify for gastropod and epiphyte-based food webs. Mercury shown obvious biomagnification potential where it can bio-magnify from trophic level as low as particulate organic matter (POM) to higher trophic of fish. These findings proved that aquatic ecosystems must be preserved from contamination not just for human benefit, but also to prevent environmental degradation and biodiversity loss.

The common nase (Chondrostoma nasus) as an indicator of aquatic pollution and human health risk assessment associated with its consumption

Individuals of common nase were sampled from three waterbodies (Kačer river, Zaovine, and Medjuvršje reservoirs) with different characteristics, types, and levels of anthropogenic pressure. The aims of this study were to determine the concentrations of 26 elements in gills, liver, and muscle using inductively coupled plasma optical emission spectrometry (ICP-OES); determine the concentrations of 17 organochlorine pesticides (OCPs) in muscle tissue using gas chromatography with mass spectrometric detection (GC-MS); compare these findings with fish condition (CF); and conduct human health risk and benefit assessments due to consumption of fish meat using target hazard quotient, target carcinogenic risk factor, Se:Hg molar ratio, Na:K and Ca:Mg ratios, and contribution of elements to human diet. Results indicated that in addition to the fact that the type of ecosystem (lentic vs. lotic) plays an important role in the fate and kinetics of pollutants, the degree of anthropogenic pressure is one of the most important factors of environmental pollution - Zaovine and Medjuvršje reservoirs (both lentic ecosystems) had the lowest and the highest levels of pollution, respectively. CF did not reflect the differences in accumulation of all analyzed elements in nase tissues. None of the 17 analyzed OCPs were detected due to the absence of recent use. Fish muscle was the least affected by metal pollution at all studied localities and could be safely used for consumption. We recorded several benefits for human health when using the nase meat in human diet.

Utilizing adsorption of wood and its derivatives as an emerging strategy for the treatment of heavy metal-contaminated wastewater

The rapid development of the industrial sector has resulted in tremendous economic growth. However, this growth has also presented environmental challenges, specifically due to the substantial sewage generated and its contribution to the early warning of global water resource depletion. Large concentrations of poisonous heavy metals, including cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and nickel (Ni), are found in industrial effluent. Therefore, various studies are currently underway to provide effective solutions to alleviate heavy metal ion pollution in sewage. One emerging strategy for sewage pollution remediation is adsorption using wood and its derivatives. This approach is gaining popularity due to the porous structure, excellent mechanical properties, and easy chemical modification of wood. Recent studies have focused on removing heavy metal ions from sewage, summarising and analysing different technical principles, affecting factors, and mainstream chemical modification methods on wood. Furthermore, this work provides insight into potential future development direction for enhanced adsorption of heavy metal ions using wood and its derivatives in wastewater treatment. Overall, this review aims to raise awareness of environmental pollution caused by heavy metals in sewage and promote green environmental protection, low-carbon energy-saving, and sustainable solutions for sewage heavy metal treatment.

Heavy Metals Assessment and Health Risk to Consumers of Two Commercial Fish Species from Polyculture Fishponds in El-Sharkia and Kafr El-Sheikh, Egypt: Physiological and Biochemical Study

Metal pollution is a major environmental concern worldwide, especially in Egypt. The aquaculture industry uses widespread artificial feeds to stimulate fish production, leading to metal accumulation in the aquatic environment. Heavy metal concentrations (HMCs) in sediments, water, and tissues were studied to study the effect of pollution levels on heamatological, and biochemical, immunological aspects of farmed fish as well as on human health. Results declared that the HMC levels in the water and sediment were significantly different between El-Sharkia and Kafr El-Sheikh fishponds (T-test, p < 0.05). This was supported by the metal pollution index in the water and sediment, indicating that El-Sharkia fishponds (ES fishponds) were more contaminated than Kafr El-Sheikh fishponds (KES fishponds). Also, HMCs in fish tissues were significantly increased in fish cultivated in ES fishponds than in KES fishponds. Haematological, immunological, and biochemical alterations of Bolti (Oreochromis niloticus) and Topara (Chelon ramada) fish were significantly different within the different fish species as well as the different fishponds. From the human health perspective, the THQ-HMC and HI-HMC associated with the consumption of muscle suggest a safe non-carcinogenic risk to human health. In contrast, cadmium poses a cancer risk to children who consume the muscular tissue of Bolti fish from ES fishponds, which should be regarded as a warning sign based on data indices and a human health perspective. In order to minimise HMC pollution in the aquaculture sector, it is advisable to take possible assessments and carry out continuous monitoring considering international WHO/FAO assessments.

Synbiotic Agents and Their Active Components for Sustainable Aquaculture: Concepts, Action Mechanisms, and Applications

Aquaculture is a fast-emerging food-producing sector in which fishery production plays an imperative socio-economic role, providing ample resources and tremendous potential worldwide. However, aquatic animals are exposed to the deterioration of the ecological environment and infection outbreaks, which represent significant issues nowadays. One of the reasons for these threats is the excessive use of antibiotics and synthetic drugs that have harmful impacts on the aquatic atmosphere. It is not surprising that functional and nature-based feed ingredients such as probiotics, prebiotics, postbiotics, and synbiotics have been developed as natural alternatives to sustain a healthy microbial environment in aquaculture. These functional feed additives possess several beneficial characteristics, including gut microbiota modulation, immune response reinforcement, resistance to pathogenic organisms, improved growth performance, and enhanced feed utilization in aquatic animals. Nevertheless, their mechanisms in modulating the immune system and gut microbiota in aquatic animals are largely unclear. This review discusses basic and current research advancements to fill research gaps and promote effective and healthy aquaculture production.

The toxicity effects of the individual and combined exposure of methyl tert-butyl ether (MTBE) and tire rubber powder (RP) on Nile tilapia fish (Oreochromis niloticus)

Methyl tert-butyl ether (MTBE) is soluble in water and can contaminate water sources when it spills during transportation or leaks from underground storage tanks. Incomplete combustion releases MTBE as exhaust fumes that can be deposited on urban surfaces. Meanwhile, car tires erosion emits of large amounts of rubber dust (RP), easily transported to water bodies. Therefore, this study has the objective of assessing the toxicity of varying concentrations of MTBE (0, 2.5, 5.0 μL L-1) and RP (0, 5.0, 10.0 mg L-1 RP), both individually and in combination, over a period of 28 days on Nile tilapia (Oreochromis niloticus). MTBE and PR decreased fish growth performance. Blood biochemical analytes indicated that MTBE and RP led to increasing Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and creatinine phosphokinase (CPK), alkaline phosphatase and gamma-glutamyl transferase (GGT) activities. Alterations related to glucose, triglycerides, cholesterol, and creatinine, plasma contents, were also observed. Increased antioxidant biomarkers, including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), glutathione reductase (GR), and malondialdehyde (MDA), was observed. Exposure fish to MTBE and PR changed metabolic profile of muscle tissue. Moreover, results showed that MTBE, its metabolites, and PR could accumulate in the muscle tissue of fish. Results suggest that MTBE and RP can impact fish health, both individually and when combined. The presence of MTBE enhances the toxicity of RP, indicating a synergistic effect. Nevertheless, further studies are needed to understand the impact of toxic compounds on aquatic environments and organisms' health.

First assessment of Rare Earth Element organotropism in Solea solea in a coastal area: The West Gironde Mud Patch (France)

Few studies exist on concentration and internal distribution of Rare Earth Elements (REEs) in marine fishes. REEs organotropism was determined in common sole (Solea solea) from the West Gironde Mud Patch (WGMP; N-E Atlantic Coast, France). The highest ∑REEs concentrations occurred in liver (213 ± 49.9 μg kg-1 DW) and gills (119 ± 77.5 μg kg-1 DW) followed by kidneys (57.7 ± 25.5 μg kg-1 DW), whereas the lowest levels were in muscles (4.53 ± 1.36 μg kg-1 DW) of Solea solea. No significant age- or sex-related differences were observed. The organotropism varied among groups of REEs. Light and heavy REEs preferentially accumulated in liver and gills, respectively. All considered organs showed different normalized REEs patterns, suggesting differences in internal distribution processes between organs. Further work should address: (1) baseline levels worldwide, and (2) factors controlling uptake and organ-specific concentration of REEs.

Single and combined effects of CuSO4 and polyethylene microplastics on biochemical endpoints and physiological impacts on the narrow-clawed crayfish Pontastacusleptodactylus

This study investigated the toxicity of polyethylene microplastics (MPs; <0.02 mm) and CuSO4, alone and in combination, on the freshwater crayfish Pontastacus leptodactylus. In this study, the crayfish were exposed to PE-MPs (0.0, 0.5, and 1 mg L-1) and CuSO4·5H2O (0.0, 0.5, and 1 mg L-1) for a period of 28 days. Next, multi-biomarkers, including biochemical, immunological, and oxidative stress indicators were analyzed. Results showed that co-exposure to PE-MPs and CuSO4 resulted in increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and decreased alkaline phosphatase (ALP), butyrylcholinesterase (BChE), and gamma-glutamyl-transferase (GGT). Triglycerides, cholesterol, glucose, and albumin content also increased. Although no significant change was observed in lysozyme and phenoloxidase activities in crayfish co-exposed to 0.5 mg L-1 MPs and 0.5 mg L-1 CuSO4, their activities were significantly decreased in other experimental groups. Oxidative stress parameters in hepatopancreas indicated increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and in malondialdehyde (MDA) levels, but decreased catalase (CAT), glucose 6-phosphate dehydrogenase (G6PDH), and cellular total antioxidant (TAC). Results showed that the sub-chronic toxicity of CuSO4 was confirmed. The study confirmed the toxicity of CuSO4 and found that higher concentrations led to more severe effects. Co-exposure to PE-MPs and CuSO4 primarily compromised the endpoints, showing increased toxicity when both pollutants were present in higher concentrations. The activities of POX, LYZ, ALP, GGT, LDH, and CAT were suppressed by both CuSO4 and MPs. However, a synergistic increase was observed in other measured biomarkers in crayfish co-exposed to CuSO4 and MPs.

Ecotoxicological insights: Effects of pesticides on ionic metabolism regulation in freshwater catfish, Mystus keletius

Fish maintain their body fluid ionic and osmotic homeostasis using sophisticated iono-/osmoregulation mechanisms through gills ionocytes. Pesticide-induced ionic imbalance in fish has been recognized as a valuable tool to determine its toxic effects. Acute exposure to synthetic and organo-chemical pesticides on the regulation of ionic (Na+, Ca2+, P) metabolism in freshwater catfish Mystus keletius was evaluated. Fish were exposed to sub-lethal concentrations (mg/l) of selected pesticide for a period of 7, 14, 21 and 28 days. Results indicated that chemical pesticides - Impala and Ekalux - evoked adverse toxic effects on selected tissues compared to organo-chemical pesticide tested. Statistical analysis of the summative data using two-way ANOVA was significant (p-value<0.001). Variations in the cellular parameters analysed were attributed to the physiological acclimatization of fish to the pesticide exposed. Based on the results it is concluded that organic pesticides may be preferred for rice field application considering safety aspects.

Seasonal assessment of selected trace elements in grass carp (Ctenopharyngodon idella) blood and their effects on the biochemistry and oxidative stress markers

Environmental pollution by anthropogenic activity is still a highly relevant global problem. Aquatic animals are a specifically endangered group of organisms due to their continuous direct contact with the contaminated environment. Concentrations of selected trace elements in the grass carp (Ctenopharyngodon idella) (n = 36) blood serum/clot were monitored. Possible effects of the elements on selected biochemical and oxidative markers were evaluated. The concentrations of trace elements (Al, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Sr, Tl, and Zn) were analysed in the fish blood serum and blood clot by inductively coupled plasma optical emission spectrometry (ICP OES). A general scheme of decreasing concentrations of trace elements in the blood serum samples was: Zn ˃ Fe ˃ Sr ˃ Ba ˃ Ni ˃ Al ˃ Cu ˃ Be ˃ Co; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mn, Mo, Pb, Tl; and in the case of the blood clot, the scheme was as follows: Fe ˃ Zn ˃ Sr ˃ Al ˃ Ni ˃ Ba ˃ Cu ˃ Be ˃ Co ˃ Mn; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mo, Pb, Tl. Significant differences among the seasons were detected. The Spearman R correlation coefficients and linear or non-linear regression were used to evaluate direct relationships between trace elements and selected blood biomarkers. The correlation analysis between biochemical parameters (Na, K, P, Mg, AST, ALT, ALP, GGT, TAG, TP, urea, glucose) and trace elements (Al, Ba, Be, Cu, Fe, Ni, Sr, and Zn) concentrations confirmed statistically significant interactions in both seasons (summer and autumn). The regression analysis between oxidative stress markers (ROS, GPx, creatinine, uric acid, and bilirubin) and elements (Al, Ba, Co, Cu, Fe, Ni, and Sr) content confirmed statistically significant interactions. The results point to numerous connections between the observed elements and the physiological parameters of freshwater fish.

Transfer of chromium from environment to fish in East Kolkata wetlands - evaluation by structural equation modeling

Chromium (Cr) is a significant pollutant in the effluents from leather industries and domestic city sewage. Cr was determined in water, sediment, and different tissues (gill, muscle, intestine, liver, and kidney) of Nile tilapia, Oreochromis niloticus harvested from wastewater-fed aquaculture (WFA) situated at Bamonghata, Bantala, Chowbaga and Chingrighata of East Kolkata Wetlands (EKW), a Ramsar site in West Bengal, India. The results showed that Cr concentration in surface water ranged between 0.05 to 0.15 mg/L, while Cr was detected at high concentration (100-300 mg/kg) in the sediment soil of the first three WFAs and in moderate concentration (50-110 mg/kg) in Chingrighata WFA. Average Cr concentrations in the tissues were ranked in the following sequence: kidney>liver>intestine>gill>muscle. However, the extent of accumulation of Cr in different tissues varied between the WFAs. We used Structural Equation Modeling (SEM) to determine the route of Cr transfer. The fitness of the model was evaluated by the performance measures. Cr accumulation pathways varied between the sites depending upon the level of Cr in water or sediment. Except for Bamonghata WFA, sediment was found as the principal source of accumulation of Cr in different tissues of O. niloticus. Cr refluxed from sediment into overlying water and accumulated in fish either through the food chain or through direct accumulation from water. In Bamonghata WFA, the role of sediment in the transfer of Cr could not be established due to the high water depth or biological non-availability of Cr in the sediment. It is concluded from this study that fish reared in the WFAs of EKW are still not hazardous in respect to Cr but require proper management to avoid the influx of Cr-containing effluents into the WFAs.

Tissue Distributions and Toxic Effects of Hexavalent Chromium in Laboratory-Exposed Periwinkle (Littorina littorea Linnaeus)

The increased use of hexavalent chromium (Cr6+) in various industrial applications has contributed to its elevated levels in the environment, especially the aquatic environment. Thus, there is the potential for accumulation of Cr6+ in the tissues of aquatic organisms and consequent toxic effects. The toxic effects of Cr6+ in aquatic organisms have been widely reported; however, little is known about the patterns of tissue accumulation of Cr6+ and its toxicity in aquatic mollusks. Thus, the present study investigated the effects of Cr6+ exposure on the tissue distribution, proximate composition, and histopathology of an aquatic mollusk, periwinkle (Littorina littorea). The animals were exposed to sublethal concentrations of Cr6+ (0.42, 0.84, and 4.2 mg/L) for 30 days, after which the condition index, tissue accumulation, proximate composition, and histopathological effects were determined. The control animals were maintained in a medium that did not contain Cr6+ (0 mg/L). The condition index did not differ significantly among the groups. The levels of Cr6+ in the tissues differed significantly among the different tissue types while there was no significant effect of the exposure concentration, except in the foot tissue. The proximate parameters (protein, carbohydrates, lipid, crude fiber, and moisture contents) differed significantly among the groups. The protein contents of the exposed animals were significantly lower than those of the control animals and the histological architecture of the major organs was altered in the chromium-exposed animals. The findings from this study indicate a low potential of L. littorea to bioaccumulate Cr6+ in its tissues at the low exposure concentrations tested in this study; as such, its consumption may not pose any serious health risks to humans. However, changes in the proximate composition and histological architecture of the exposed L. littorea show that Cr6+ is potentially toxic to periwinkles.

Unveiling the molecular mechanisms and developmental consequences of mercury (Hg) toxicity in zebrafish embryo-larvae: A comprehensive approach

Mercury (Hg) is a global contaminant affecting aquatic ecosystems' health. Chronic exposure to Hg has shown that the normal development of zebrafish embryo-larvae is affected. However, the molecular mechanisms behind the toxicity of Hg on fish embryonic development are still poorly understood. This work aimed to investigate the effects of Hg exposure on zebrafish embryo-larvae using a combined approach at individual (mortality, embryo development and locomotor behavior) and biochemical (neurotoxicity and oxidative stress enzymatic activities and protein phosphatase expression) levels. The Fish Embryo Toxicity assay followed the Organization for Economic Cooperation and Development Guideline 236 and used a concentration range between 13 and 401 μg Hg/L. Lethal and developmental endpoints were examined at 24, 48, 72 and 96 hpf. Biochemical markers, including Acetylcholinesterase (AChE), Catalase (CAT), Glutathione Reductase (GR), and Glutathione-S-Transferase (GST) activities and, for the first time, the expression of the protein phosphatase 1 gamma (PP1γ) was assessed after 24, 48, 72 and 96 h of exposure to 10 and 100 μg Hg/L. The behavioral effects of a sublethal range of Hg (from 0.8 to 13 μg Hg/L) were assessed using an automated video tracking system at 120 hpf. Several developmental abnormalities on zebrafish embryos and larvae, including pericardial edema, spin and tail deformities and reduced rate of consumption of the yolk sac, were found after exposure to Hg (LC50 at 96 hpf of 139 μg Hg/L) with EC50 values for total malformations ranging from 22 to 264 μg Hg/L. After 96 hpf, no significant effects were observed in the CAT and GR activities. However, an increase in the GST activity in a concentration and time-dependent manner was found, denoting possible stress-related adaptation of zebrafish embryos to deleterious effects of Hg exposure. The AchE activity showed a response pattern in line with the behavioral responses. At the lowest concentration tested, no significant effects were found for the AChE activity, whereas a decrease in AChE activity was observed at 100 μg Hg/L, suggesting that exposure to Hg induced neurotoxic effects in zebrafish embryos which in turn may explain the lack of equilibrium found in this study (EC50 at 96 hpf of 83 μg Hg/L). Moreover, a decrease in the PP1γ expression was found after 96 h of exposure to 10 and 100 μg Hg/L. Thus, we suggest that Hg may be an inhibitor of PP1γ in zebrafish embryos-larvae and thus, along with the alterations in the enzymatic activity of GST, explain some of the developmental malformations observed, as well as the lack of equilibrium. Hence, in this study, we propose the use of PP1 expression, in combination with apical and biochemical endpoints, as a precursor for assessing Hg's toxic mechanism on embryonic development.

Ameliorative effect of natural floating island as fish aggregating devices on heavy metals distribution in a freshwater wetland

Growing human population and climate change are leading reasons for water quality deterioration globally; and ecologically important waterbodies including freshwater wetlands are in a vulnerable state due to increasing concentrations of pollutants like heavy metals. Given the declining health of these valuable resources, the present study was conducted to evaluate the effect of natural floating island in the form of fish aggregating devices (FADs) made of native weed mass on the distribution of heavy metals in the abiotic and bio compartments of a freshwater wetland. Lower concentrations of surface water heavy metals were observed inside the FADs with a reduction of 73.91%, 65.22% and 40.57-49.16% for Cd, Pb and other metals (viz. Co, Cr, Cu, Ni and Zn), respectively as compared to outside FAD. These led to 14.72-55.39% reduction in the heavy metal pollution indices inside the FAD surface water. The fish species inside the FADs were also found less contaminated (24.07-25.07% reduction) with lower health risk indices. The study signifies the valuable contribution of natural floating island as FADs in ameliorating the effect of heavy metals pollution emphasizing the tremendous role of the natural floating islands in sustainable maintenance of freshwater wetlands for better human health and livelihood.

Human health risk assessment of potentially toxic elements and microplastics accumulation in products from the Danube River Basin fish market

The present study aimed to quantify the concentration levels of potentially toxic elements (PTEs) such as aluminum, arsenic, cadmium, chromium, copper, nickel, lead, zinc, and mercury, as well as microplastics occurrence in various tissues of fish and seafood species, commercialized in the Lower Danube River Basin. A health risk assessment analysis was performed based on the PTEs concentration levels in the muscle tissue. Estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TR) of PTEs were calculated. It was observed that the species within the seafood category registered the highest levels of PTEs. For instance, in the muscle tissue of bivalve Mytilus galloprovincialis (from the Black Sea), the highest value was observed in the case of Zn (37.693 mg/kg), and the presence of polystyrene polymer was identified. The values associated with EDI, THQ, HI, and TR of PTE exposure were significantly lower than 1.

Toxicity of co-exposure of microplastics and lead in African catfish (Clarias gariepinus)

Microplastics (MPs) are an emerging threat to freshwater ecosystems with several ecotoxicological ramifications for fish. Microplastics (MPs) can adsorb heavy metals on their surfaces and increase their availability to aquatic organisms. The combined impact of lead and microplastics on fish has only been studied seldom utilizing a variety of markers. The present study aimed to evaluate the hematological, biochemical, and inflammatory signals (cytokines), as well as antioxidant enzymes in African catfish (Clarias gariepinus) exposed to lead (Pb) and MPs individually and combined for 15 days (acute toxicity experiment). The fish were split into four groups, the first of which was the control group. The second group received exposure to 1 mg/L of lead nitrate [Pb(NO3)2]. The third group was given 100 mg/L of MPs. A solution containing 100 mg/L of MPs and 1 mg/L of lead nitrate [Pb(NO3)2] was administered to the fourth group (the combination group). According to the findings, when MPs and Pb were combined for 15 days, the red blood cells (RBCs), thrombocytes, and lymphocytes were significantly reduced in comparison to the control fish. When compared to the control fish, the fish exposed to MPs and Pb alone or together showed a significant rise in blood interleukin-1β (IL-1β) and interleukin-6 (IL-6) cytokines. Both MPs and Pb exposure in catfish resulted in significant changes in the plasma electrolytes. The fish treated with MPs and Pb individually or in combination showed significant reduction in superoxide dismutase (SOD) and total antioxidant capacity (TAC) levels compared to the control group. The fish exposed to the combined action of MPs and Pb showed a considerable modification in all biochemical markers. The difference in the mean concentration of Pb (mg/L) between the fish exposed to Pb alone and the fish subjected to Pb and MPs combination was not statistically significant. In conclusion, according to this investigation, exposure to Pb caused an insignificant increase in Pb accumulation when MPs were present. However, co-exposure may result in anemia, cellular harm, extremely high levels of oxidative stress, and an inflammatory reaction.

Effects of cooking methods and co-ingested foods on mercury bioaccessibility in pontic shad (Alosa immaculata)

Human mercury (Hg) exposure is mostly caused by eating fish. However, there are major differences between the measured and predicted mercury concentration on Hg bioavailability. This study investigated the effects of cooking (steaming, baking, frying, marinating, and smoking) and selected components' co-ingestion on Hg bioaccessibility. Baking and frying reduced Hg bioaccessibility compared to the raw sample. The bioaccessible Hg fraction in fish was assessed through in vitro digestion method. Hg bioaccessibility varied from 4.31 to nearly 24.95% and the Hg recovery rate varied from 63.44 to 78.74%. Co-ingested garlic and broccoli with pontic shad had a positive effect on decreasing fish Hg bioaccessibility. The antioxidant activity of co-ingested food items was also calculated and correlated with mercury bioaccessibility. These results highlighted a possible positive role of plant-based foods and other food processing techniques in the bioaccessibility reduction of other chemical contaminants found in food sources.

Lead induced structural and functional damage and microbiota dysbiosis in the intestine of crucian carp (Carassius auratus)

Lead (Pb) is a hazardous pollutant in water environments that can cause significant damage to aquatic animals and humans. In this study, crucian carp (Carassius auratus) were exposed to waterborne Pb for 96 h; then, histopathological analysis, quantitative qPCR analysis, and 16S high-throughput sequencing were performed to explore the effects of Pb on intestinal bioaccumulation, structural damage, oxidative stress, immune response, and microbiota imbalance of C. auratus. After Pb exposure, the intestinal morphology was obviously damaged, including significantly increasing the thickness of the intestinal wall and the number of goblet cells and reducing the depth of intestinal crypts. Pb exposure reduced the mRNA expressions of Claudin-7 and villin-1 while significantly elevated the level of GST, GSH, CAT, IL-8, IL-10, IL-1, and TNF-α. Furthermore, 16S rRNA analysis showed that the Shannon and Simpson indices decreased at 48 h after Pb exposure, and the abundance of pathogenic bacteria (Erysipelotrichaceae, Weeksellaceae, and Vibrionaceae) increased after Pb exposure. In addition, the correlation network analysis found that Proteobacteria were negatively correlated with Firmicutes and positively correlated with Bacteroidetes. Functional prediction analysis of bacteria speculated that the change in intestinal microbiota led to the PPAR signaling pathway and peroxisome function of the intestine of crucian carp was increased, while the immune system and membrane transport function were decreased. Finally, canonical correlation analysis (CCA) found that there were correlations between the intestinal microbiota, morphology, antioxidant factors, and immune factors of crucian carp after Pb exposure. Taken together, our results demonstrated that intestinal flora dysbiosis, morphological disruption, oxidative stress, and immune injury are involved in the toxic damage of Pb exposure to the intestinal structure and function of crucian carp. Meanwhile, Pb exposure rapidly increased the abundance of pathogenic bacteria, leading to intestinal disorders, further aggravating the damage of Pb to intestinal structure and function. These findings provide us a basis for the link between gut microbiome changes and heavy metal toxicity, and gut microbiota can be used as biomarkers for the evaluation of heavy metal pollution in future.

Bioenrichment preference and human risk assessment of arsenic and metals in wild marine organisms from Dapeng (Mirs) Bay, South China Sea

Bioenrichment preference of arsenic and metals in wild marine organisms has been scarcely considered. Twenty species including fishes, cephalopods, crustaceans, and bivalve mollusks were collected from Dapeng (Mis) Bay and analyzed for arsenic and metals. Through this study, we had obtained the following four main conclusions: (1) average concentrations of arsenic and metals (μg/kg, wet weight) in the aquatic organism samples were 48.7 for Cr, 1762.0 for Mn, 20,632.8 for Fe, 33.0 for Co, 119.5 for Ni, 3184.7 for Cu, 12,040.5 for Zn, 389.0 for As, 189.1 for Se, 144.4 for Cd, 15.0 for Hg, and 55.3 for Pb; (2) factor analysis (FA) revealed that the studied twenty species exhibited three types of arsenic and metal bioenrichment preference;(3) non-carcinogenic health risk assessment indicated insignificant health effects from marine organism consumption; (4) carcinogenic health risk assessment revealed an unacceptable risk from consumption of nine species, seven of which were crustaceans.

Impacts of dietary zinc oxide nanoparticles on the growth and immunity of Nile tilapia could be ameliorated using Nigella sativa oil

BACKGROUND

Zinc nanoparticles are documented to be harmful to fish because their accumulation in fish bring about many irreversible changes in their health. Nigella sativa and its oil have been endorsed in aquaculture to improve fish health.

METHODS

Two hundred seventy experimental fish (113 ± 5 g body weight) were divided into 6 groups G1-6; control fish fed a diet without any treatment (G1), 0.3% of NSO (G2), 0.5% of NSO (G3), ZnO NPs (40 mg/kg diet) (G4), 0.3% of NSO and ZnO NPs (40 mg/kg diet) (G5), 0.5% of NSO and ZnO NPs (40 mg/kg diet) (G6), the trial lasted for six weeks.

RESULTS

Growth performance was enhanced in fish received diets containing NSO, final weight (FW), weight gain (WG), daily weight gain (DWG), and relative growth rate (RGR) were significantly increased with lower food conversion ratios (FCR) compared to the control. The hepatic glutathione peroxidase (GPx), catalase (CAT), and metallothionein (MT) were increased in response to ZnO NPs stress and only 0.5% NSO supplementation could ameliorate such increment. The immune-related genes [interleukin1-beta (IL-1β), tumor necrosis factor-beta (TNF-β), transforming growth factor-beta 2 (TGF-β2) and C-type lysozyme] as well as growth-related gene [insulin-like growth factor 1 (IGF1)] in liver showed an upregulation in fish fed with NSO diets. Administration of ZnO NPs lowered the resistance of Oreochromis niloticus against bacterial infection with Aeromonas hydrophila and NSO could enhance the immunity in the highest tested concentration (0.5%) (G₆).

CONCLUSIONS

The obtained results implied that NSO could enhance the oxidative and immune status of O. niloticus which could compensate ZnO NPs stress as well as experimental infection of a virulent strain of A. hydrophila. Our results revealed that NSO might increase fish growth and immunity only at a high dose (0.5%).

Metalliferous atmospheric settleable particulate matter action on the fat snook fish (Centropomus parallelus): Metal bioaccumulation, antioxidant responses and histological changes in gills, hepatopancreas and kidneys

Metallic smoke released by steel industries is constitute by a mixture of fine and gross particles containing metals, including the emerging ones, which sedimentation contaminates soil and aquatic ecosystems and put in risk the resident biota. This study determined the metal/metalloids in the atmospheric settleable particulate matter (SePM, particles >10 μm) from a metallurgical industrial area and evaluated metal bioconcentration, antioxidant responses, oxidative stress, and the histopathology in the gills, hepatopancreas and kidneys of fat snook fish (Centropomus parallelus) exposed to different concentrations of SePM (0.0, 0.01, 0.1 and 1.0 g L^-1), for 96 h. From the 27 metals (Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, Sn, Ba, La, Ce, W, Hg, Pb, Bi) analyzed, 18 were quantified in SePM and dissolved in seawater. Metal bioconcentrations differed among organs; Fe and Zn were the metals most bioconcentrated in all organs, Fe was higher in hepatopancreas and Zn > Fe > Sr > Al was higher in kidneys. The activity of superoxide dismutase (SOD) decreased in the gills; SOD, catalase (CAT) decreased, and glutathione peroxidase (GPx) increased in hepatopancreas and, CAT, glutathione-S-transferase (GST) and the level of glutathione (GSH) increased in kidneys. The unchanged levels of lipid peroxidation and oxidized protein in any organ indicate that the antioxidant responses were efficient to avoid oxidative stress. Organ lesion indices were higher in the gills > kidneys > hepatopancreas, being higher in fish exposed to 0.01 g L^-1 SePM. All changes indicate a tissue-specific metal/metalloids bioconcentration, antioxidant and morphological responses that all together compromise fish health. Regulatory normative are needed to control the emission of these metalliferous PM to preserve the environment and biota.