Search Results (417)

Understanding individual growth is essential for assessing exploitation status and supporting sustainable fishery management. For the southern Brazilian stock of the mullet Mugil liza, previous growth estimates were based on whole otolith readings and included few young individuals, potentially influencing growth parameter estimation and stock assessment outputs. In this study, daily otolith microincrements of juveniles were validated using oxytetracycline (OTC) marking and combined with age–length data from a previous study to evaluate the effect of incorporating validated juvenile ages into von Bertalanffy growth function estimates. The updated model yielded a 15% smaller asymptotic length (564 mm), a 47% higher growth coefficient (0.28 yr⁻¹), and a theoretical age at zero length closer to biologically plausible values (t0 = −0.11). Revised growth parameters were incorporated into an age-structured production model (ASPM). Although temporal trends in spawning biomass and fishing mortality remained similar, substantial differences were observed in biomass scale and biological reference points. These findings highlight the sensitivity of stock assessment outputs to growth parameterization and the importance of adequately representing early life stages in growth models. Full article

Marine biowaste (fish and crustacean processing residues) is produced in tens of millions of tons annually, yet remains dramatically underutilized as a feedstock. Hydrothermal carbonization offers a technically attractive valorization route for these high-moisture, non-lignocellulosic materials, converting them to carbon-enriched hydrochar without the energy-intensive pre-drying required by pyrolysis. This focused review treats marine animal waste as the primary studies and micro- and macroalgal hydrothermal carbonization as a comparative benchmark to understand how the current research is going, the impact of production parameters, potential application, and possible research gaps to explore. Crustacean waste yields substantially more hydrochar (37–69%) than fish waste (15–34%) under equivalent conditions, driven by calcium carbonate retention in the solid phase. Unactivated hydrochars have low BET surface areas (<30 m²/g) and modest adsorption capacities (~10 mg/g). Acid deashing followed by KOH activation at 700 °C unlocks nanoporous structures with BET surface areas up to 680 m²/g and oxytetracycline adsorption capacities of 61.3 mg/g. Critical research gaps include the absence of techno-economic analysis, limited life-cycle assessment, and non-standardized reporting conventions. These must be addressed before upscaling to industrial viability can be achieved. Full article

Tetracyclines (TCs) are antibiotics widely used in human and veterinary medicine as well as in agricultural practices. They may be retained in soil or drift into freshwater, thereby exerting effects on non-target organisms and deteriorating ecological quality. In this study, tetracycline (T), oxytetracycline (OT), chlortetracycline (CT), and their binary and ternary mixtures were evaluated using a battery of bioassays including terrestrial plants, aquatic crustaceans, a ciliate protist and a bacterial species. Results showed a concentration-dependent effect for parameter immobilization in Daphnia magna and Artemia salina, seed germination in the terrestrial plants, and bioluminescence inhibition and growth inhibition in Aliivibrio fischeri and Tetrahymena thermophila, respectively. For A. fischeri, statistically significant interactions were observed between dose and exposure time. A. salina demonstrated greater sensitivity than D. magna in all cases. Both A. salina and A. fischeri showed increased toxicity to OT and the ternary mixture. Dicots presented greater sensitivity than the monocot species in all cases. In the combined exposures, there was a deviation from the concentration addition (CA) model, with possible synergism for CT + T and the ternary mixture for A. fischeri. The concurrent environmental exposure of non-target organisms to TCs should be investigated further. Full article

The Yellow River Delta (YRD), a crucial ecotone, is becoming increasingly polluted by antibiotics, posing serious threats to aquatic ecosystems and human health. In this study, comprehensive investigations were conducted to explore the regional distribution, environmental risks, and source apportionment of antibiotics, with the aim of facilitating precise management and control of antibiotic pollution. The results show that the surge in runoff during the water–sediment regulation period (June and August) of the Yellow River drove a sharp rise in antibiotic concentrations in the surface water, peaking at 135.0 ng/L, whereas antibiotics were rarely detected in the sediments after multiple rounds of intense hydraulic scouring (0.2~12.6 ng/g in October). Furthermore, seven antibiotics (sulfadiazine, sulfamethoxazole, flumequine, ofloxacin, tetracycline, doxycycline, and lincomycin) in surface water and six antibiotics (norfloxacin, enrofloxacin, ofloxacin, doxycycline, oxytetracycline, and florfenicol) in sediments were identified as representative compounds according to the antibiotic pollution profiles. Environmental risk assessment coupled with spatial autocorrelation analysis revealed that sulfamethoxazole generally posed medium to high risk (0.12~1.27) in surface water. Sediments posed more serious ecological risks, with universally high risk levels (ranging from 1.11 to 280.00). More importantly, in both surface water and sediment, four core antibiotic sources—namely, human sewage, livestock farming, agricultural and aquaculture inputs, and hydrodynamic-driven resuspension processes—were consistently identified through the Positive Matrix Factorization model and Kriging interpolation. These findings provide crucial insights for establishing targeted antibiotic pollution control strategies in the YRD and advance the understanding of antibiotic fate in sediment-laden rivers. Full article

Tetracycline-class antibiotics are persistent contaminants in aquatic environments and are difficult to remove by conventional treatment processes. In this study, a recoverable granular MIL-101(Fe)/γ-Al₂O₃ catalyst was prepared through ligand anchoring followed by secondary Fe-MOF growth on spherical γ-Al₂O₃ and applied to catalytic ozonation of tetracycline (TC) under ordinary-bubble and microbubble-assisted operation. Structural characterization supported the formation of Fe-containing MOF domains on the alumina support, accompanied by an increase in BET surface area from 164.28 to 210.05 m² g⁻¹ and enhanced Lewis-acid-related pyridine-IR signals. Under conventional bubbling ozonation, the optimized catalyst achieved 67.93% apparent UV–Vis-based TC removal during an overall 50 min run consisting of 30 min dark adsorption followed by 20 min ozonation. In a 12 L microbubble reactor, the catalyst-assisted system reached 93.74% apparent UV–Vis-based TC removal at pH 6 with 100 g catalyst and 6 mg min⁻¹ fed ozone, showing higher apparent removal than ordinary ozonation, microbubble ozonation, and ordinary-bubble catalytic ozonation under the tested configuration. Phosphate-blocking and radical-quenching experiments were consistent with the involvement of Lewis-acid-related sites, hydroxyl radicals, and superoxide-related pathways, but these tests are interpreted as indirect mechanistic evidence. LC-MS analysis suggested possible hydroxylation, demethylation, deamidation, ring opening, and low-molecular-weight product formation. The system also transformed chlortetracycline, oxytetracycline, and doxycycline and reduced COD and TOC in a simulated mixed-antibiotic matrix. Because parent-compound HPLC/LC-MS time-series quantification, ozone utilization/off-gas ozone measurement, bubble-size/kLa analysis, and ICP-based Fe loading/leaching data were not available, the present work is positioned as an apparent catalyst–reactor coupling study rather than a complete catalytic, hydrodynamic, or process-level demonstration. Full article

Oxytetracycline (OTC) is widely used in aquaculture to treat bacterial diseases, but its effects on drug metabolism and immune responses remain poorly understood in olive flounder (Paralichthys olivaceus). This study investigated the effects of OTC immersion for 1 h at different concentrations on the expression profile of drug metabolism- and immune-related genes and the histopathological changes in the gills and liver of olive flounder. The expression of Paralichthys olivaceus cytochrome P450 (PoCYP), Paralichthys olivaceus diphosphate (UDP)-glucuronosyltransferases (PoUGTs), and immune-related genes significantly increased at 12 and 24 h and then decreased at 72 h in the 100 and 200 ppm groups. By contrast, the 400 ppm group exhibited variable expression patterns depending on the gene and tissue. The highest expression levels were observed for PoIL-1β in the gills (22.7-fold) and PoCYP27B1 in the liver (58.0-fold) in the 400 ppm group. Histopathological analysis revealed macrophage activation in the liver at 72 h in the 200 ppm group, whereas epithelial edema and mild aneurysmal changes in the gills and macrophage activation in the liver were observed in the 400 ppm group. These findings provide insights into the effects of OTC exposure on drug metabolism and immune responses in olive flounder. Full article

Glyphosate (Gly) is currently the most commonly used broad-spectrum herbicide in the world. The extensive residues of Gly and its major metabolite aminomethylphosphonic acid (AMPA) in food and the environment make it inevitable for humans to consume them. Although Gly has been shown to disturb the homeostasis of gut microbiome by inhibiting the shikimic acid pathway of microorganisms, the potential health effects [such as the occurrence of antibiotic resistance genes (ARGs)] remain unclear. Furthermore, as antibiotics that also act on the intestinal microbiota, their extensive residues inevitably lead to co-exposure with Gly. For these reasons, this study used zebrafish as experimental organisms to explore the effects of Gly/AMPA and oxytetracycline (OTC) exposure alone or in combination on ARGs in the intestine. Our results indicate that Gly exposure, rather than AMPA exposure, led to a 1.67-fold increase in the relative abundance of ARGs in the zebrafish intestine. Combined exposure to Gly and OTC led to a 2.30-fold increase in the relative abundance of ARGs in the zebrafish intestine, indicating a synergistic effect, whereas the additive effect of AMPA and OTC was negligible. In conclusion, the health risk of antibiotic resistance caused by Gly through the gut microbiota is a neglected hot topic. Further studies are needed to clarify Gly-induced functional drug resistance and to assess the human relevance of these findings using more appropriate model organisms. Full article

The extensive use of oxytetracycline (OTC) poses significant threats to aquatic ecosystems, necessitating efficient removal strategies. While photocatalytic technology is a promising approach, single catalysts, like UiO-66-NH₂ and Bi₂MoO₆, suffer from rapid photogenerated carrier recombination and narrow light absorption. To address this, a Z-scheme heterojunction photocatalyst, Bi₂MoO₆/UiO-66-NH₂, was synthesized via a solvothermal method to enhance OTC degradation. Characterization results showed that the composite expanded visible-light absorption and improved electron-hole separation. Under simulated sunlight, the optimized composite (BUN80) achieved an OTC removal efficiency of 87.68% within 120 min under optimized conditions. The catalyst retained photocatalytic activity over five consecutive cycles, although a decrease in removal efficiency was observed. Radical trapping experiments indicated that h⁺ and •O₂⁻ were the main reactive species, and a proposed Z-scheme charge transfer pathway was suggested based on band structure analysis and photoelectrochemical results. LC-MS analysis identified 17 intermediate products, and ECOSAR-based toxicity prediction suggested a decreasing trend in aquatic toxicity during the degradation process. These findings indicate that Bi₂MoO₆/UiO-66-NH₂ is a promising photocatalyst for OTC degradation in water. Full article

Recently, a strain of Streptococcus agalactiae serotype Ia sequence type 7 clonal complex 1 (SaIa ST7 CC1) has emerged in Latin American tilapia aquaculture as an international threat. This study evaluated outbreaks of acute streptococcosis occurring between 2021 and 2025 on commercial Nile tilapia (Oreochromis niloticus) farms in six Latin American countries, aiming to integrate molecular, clinical, pathological, and environmental data. In total, 360 moribund or recently dead fish at various production stages (larvae/fry, pre-grow-out, and grow-out) were examined, and 25 S. agalactiae isolates were serotyped and subjected to real-time PCR analysis, multilocus sequence typing (MLST), virulence and antimicrobial resistance gene profiling, and antimicrobial susceptibility testing. All isolates belonged to SaIa and shared the same ST7 CC1 MLST profile, forming a highly homogeneous cluster with reference SaIa ST7 CC1 strains previously isolated from tilapia farms in Asia. These results are consistent with the regional spread of a single clonal line. At the larval and fry stages, SaIa ST7 CC1 was associated with hyperacute septicemia, gastrointestinal hemorrhage, and frequent intestinal intussusception, whereas in pre-grow-out and grow-out fish, neurological signs were more prominent, followed by ocular signs, systemic hemorrhages, and coelomic lesions. Histopathological examination showed profuse colonization of the brain, spleen, liver, and intestine by Gram-positive cocci, accompanied by marked acute circulatory and inflammatory lesions and few chronic granulomatous responses, consistent with a rapidly progressing, highly aggressive infectious process. All outbreaks occurred during extended periods of warm water (>32 °C), with large day–night thermal gradients and reduced dissolved oxygen, suggesting that thermal stress may exacerbate disease expression in affected systems. All SaIa ST7 CC1 strains exhibited phenotypic susceptibility to florfenicol and amoxicillin, whereas 84% (21/25) and 100% (25/25) exhibited intermediate susceptibility to oxytetracycline and enrofloxacin, respectively. In total, 5 of the 21 isolates (23.8%) with intermediate susceptibility to oxytetracycline carried tetracycline resistance genes (tetM, tetO). These findings identify SaIa ST7 CC1 as a clinically significant emerging threat associated with thermally facilitated and geographically expanding streptococcosis in tilapia production in Latin America. Immediate priorities include screening imported broodstock using MLST or whole-genome sequencing (WGS), harmonized regional molecular surveillance, climate-adaptive farm management practices, prudent antimicrobial use, and serotype-matched vaccination and breeding strategies that improve both disease and heat resilience. Full article

Background/Objectives: Pet birds are increasingly recognized as potential reservoirs of zoonotic and antimicrobial-resistant bacteria, raising concerns within the One Health framework. However, data on bacterial diversity and resistance profiles in clinically affected ornamental birds remain limited. Methods: This study, conducted over three years (November 2022–March 2026), included 198 pet birds presenting with digestive and respiratory disorders. From these birds, clinical samples were analyzed bacteriologically; resulting isolates were identified by MALDI-TOF mass spectrometry, and antimicrobial susceptibility assessed using the Kirby-Bauer disk diffusion method according to EUCAST and CLSI guidelines. Results: Bacterial growth was detected in 87.9% of cases, yielding 249 distinct isolates. Gram-positive cocci predominated (62.3%), led by Staphylococcus spp. (33.3%) and Enterococcus spp. (9.6%), while Escherichia coli (9.2%) was the primary Gram-negative species. At the genus level, Staphylococcus spp. demonstrated high susceptibility to amikacin (88.5%) but significant resistance to gentamicin (75.6%) and oxytetracycline (63.6%). In contrast, Escherichia spp. isolates were largely resistant, showing only 50% susceptibility to enrofloxacin and 40% to doxycycline, with resistance to tylosin reaching 90%. Overall, 57% of isolates were multidrug-resistant, with Staphylococcus spp. contributing most to this burden. Conclusions: These findings characterize clinically ill pet birds as significant carriers of multidrug-resistant bacteria, highlighting the need for routine diagnostics and improved antimicrobial stewardship in avian medicine. Full article

This work focused on synthesizing MgSiO₃ (0%Mo@MgSi), 2.5%MoO3@MgSiO₃ (2.5%Mo@MgSi), 5%MoO₃@MgSiO₃ (5%Mo@MgSi), and 10%MoO₃@MgSiO₃ (10%Mo@MgSi) by a single-step process utilizing butylated hydroxytoluene (BYHT) as a novel capping agent. The X-ray diffraction analysis of the synthesized nanohybrids indicated amorphous nanohybrids, while the energy-dispersive X-ray spectroscopy results illustrated variations in the MoO₃ doping dosages. The 0%Mo@MgSi, 2.5%Mo@MgSi, 5%Mo@MgSi, and 10%Mo@MgSi nanohybrids exhibited average sizes of 17.6, 12.2, 11.7, and 9.9 nm, respectively, and surface areas of 43.53, 40.95, 42.17, and 44.98 m²·g⁻¹, respectively. The examination of 0%Mo@MgSi, 2.5%Mo@MgSi, 5%Mo@MgSi, and 10%Mo@MgSi nanohybrids toward the oxytetracycline (OTC) sorption resulted in q_t values of 72.89, 116.89, 98.39, and 78.46 mg·g⁻¹, respectively. The OTC sorption onto the 0%Mo@MgSi, 2.5%Mo@MgSi, 5%Mo@MgSi, and 10%Mo@MgSi aligned with the nonlinear pseudo-second order model, and both the intraparticle and liquid-film diffusion models co-influenced the OTC sorption onto the four nanohybrids. Increasing the temperature decreased OTC sorption on 2.5%Mo@MgSi, indicating exothermic sorption. The Langmuir isotherm model was more suitable than the Freundlich model for describing OTC adsorption on 2.5%Mo@MgSi. The Dubinin–Radushkevich energy (E_D ≤ 8.0 kJ·mol⁻¹) and the Gibbs free energy (ΔG° ≤ 20 kJ·mol⁻¹) supported each other’s outcomes about the OTC removal onto 2.5%Mo@MgSi being via physisorption. The ΔG° values increased proportionally with temperature, indicating that OTC sorption becomes more spontaneous as temperature decreases. Moreover, the 2.5%Mo@MgSi exhibited excellent stability in OTC elimination up to the third cycle. Full article

The overuse of antibiotics has led to their widespread environmental residues, posing a significant threat to the ecological environment. In this study, a flower-like spherical CoFe-layered double hydroxide (CoFe-LDH) catalyst was prepared using a hydrothermal method. The degradation performance of the CoFe-LDH/peroxymonosulfate (PMS) system was systematically investigated using tetracycline (TC) as a model pollutant. The CoFe-LDH exhibited a three-dimensional nanoflower-like spherical structure formed by interlaced nanosheets, featuring smooth surfaces and well-defined edges. This hierarchical porous structure facilitates the exposure of active sites. The CoFe-LDH/PMS system demonstrated remarkable degradation efficiency, achieving over 90.17% TC removal within 10 min. As the dosage of CoFe-LDH and PMS increases, the degradation rate of TC improves significantly, but the marginal improvement effect decreases. TC degradation efficiency increased with pH up to an optimum at pH 5.0, beyond which it declined. The anions—Cl⁻, $\mathrm{N}{\mathrm{O}}_3^{-}$, and $\mathrm{S}{\mathrm{O}}_4^{2-}$—all exhibited inhibitory effects on TC degradation; the TC removal rates decreased to 77.88%, 80.58%, and 82.78%, respectively. The removal experiments of different organic pollutants, such as oxytetracycline (88.91%), methylene blue (98.36%), and ciprofloxacin (84.52%), as well as actual water experiments, such as lake water (92.48%) and tap water (80.86%), have demonstrated the good universality of the CoFe-LDH/PMS system. Radical quenching experiments confirmed that ^•OH and $\mathrm{S}{\mathrm{O}}_4^{•-}$ were the dominant reactive species. Full article

Tetracycline antibiotics are increasingly detected in aquatic environments because of their ecological risks and persistence, while conventional wastewater treatment processes are often insufficient for their effective removal from water. Here, we introduce a novel 3D graphene oxide-based nanocomposite that stacks Cu-NPs and amino-functionalized MIL-101(Fe) (denoted by Cu/NH₂-MIL-101(Fe)@GO) to effectively remove tetracycline (TC) and oxytetracycline (OTC) from environmental water samples. XPS, XRD, TEM, SEM, and FTIR analyses were conducted to characterize the structure and surface morphology of the Cu/NH₂-MIL-101(Fe)@GO nanocomposite. Overall, it was confirmed that GO, NH₂-MIL-101(Fe), and Cu-NPs were successfully incorporated, resulting in a porous material with high access to Cu-related sites as well as oxygen- and nitrogen-based functionalities (such as amino-, hydroxy-, and carboxy-groups). This hybrid system facilitates the adsorption by complementary mechanisms like surface complexation/chelation at Cu and Fe centers with the pH-dependent tetracycline species in electrostatic interactions, hydrogen bonding, π–π stacking, and molecule confinement in the metal–organic framework (MOF) pores, and by the synergistic effects at the GO–MOF(Fe)–Cu junction interfaces. The batch adsorption studies showed that the quick and efficient uptake of the two antibiotics at pH 6.5, with removal rates of 99.65–99.83%, was achieved by 15.0 mg of Cu/NH₂-MIL-101(Fe)@GO at an initial concentration of 20 ppm in 40 min at 25 °C. Equilibrium data were found to be well-fitted by the Langmuir isotherm (R² = 0.908–0.909), suggesting monolayer-dominated adsorption with the maximum capacity of 769.8–775.2 mg g⁻¹. The adsorption kinetics was well-described by the pseudo-second order model (R² = 0.9641–0.9749), which agreed with the strong binding between the tetracyclines and active sites of the nanocomposite. The main novelty of this work consists of the design of a single recoverable platform integrating GO-based preconcentration, pore accessibility of NH₂-MIL-101(Fe), and Cu-driven complexation, which led to the strong removal of tetracyclines under a relevant range of water conditions. These findings demonstrate that Cu/NH₂-MIL-101(Fe)@GO could serve as a promising high-efficiency and potentially reusable adsorbent for removing tetracycline from aqueous solution, which provides a more sustainable approach for pharmaceutical wastewater treatment. Full article

This work presents a novel integrative approach to the design and computational modeling of a bioreactor system for the enzymatic removal of antibiotics from aquatic environments. The study focuses on a three-dimensional mathematical model developed to resolve the diffusion–convection–reaction dynamics within the system. Programmed in MATLAB R2025a, the model integrates theoretical equations to determine the diffusion and convection coefficients, while the reaction rate constant was precisely determined through the experimental degradation data of oxytetracycline. To support this modeling, laccase was covalently immobilized on a chemically modified polylactic acid (PLA) matrix, achieving a 95.6% immobilization yield. Simulation results revealed that the system is primarily governed by the convection constant and that degradation efficiency is significantly optimized by reducing the reactor’s internal diameter. These findings demonstrate that the coupling of theoretical transport phenomena with experimentally derived kinetics provides a high-resolution tool for predicting bioreactor performance. By combining biocatalysis, materials science, and computational modeling, this research offers a scalable and environmentally friendly solution with direct implications for the development of advanced water treatment technologies. Full article

Conventional powdered biochar encounters severe bottlenecks in practical water treatment, such as difficult separation, easy loss, and potential secondary pollution. This work aimed to develop recyclable and high-performance adsorbents by preparing iron-doped biochar/sodium alginate composite microspheres (BC/MBC500-ALF) through Fe³⁺ cross-linking. Using corn stalk biochar and KMnO₄-modified biochar as adsorbent components and sodium alginate (SA) as a green shaping matrix, SA formed a stable egg-box hydrogel network to convert powdered biochar into uniform microspheres. Batch adsorption experiments revealed that the optimal pH for oxytetracycline (OTC) adsorption was 9, with adsorption capacities of 136.28 mg/g for BC500-ALF and 182.91 mg/g for MBC500-ALF. Kinetic analysis showed that BC500-ALF followed pseudo-first-order kinetics (R² = 0.983) dominated by physisorption, while MBC500-ALF fitted pseudo-second-order kinetics (R² = 0.994) dominated by chemisorption. The maximum Langmuir adsorption capacities at 308 K were 220.75 mg/g and 495.05 mg/g, respectively. Thermodynamic parameters confirmed a spontaneous and endothermic process. The adsorption mechanisms involved hydrogen bonding, π–π stacking, electrostatic attraction, metal-bridging complexation, and Fe–Mn oxide-mediated redox reactions. SA exerted dual functions in structure stabilization and adsorption enhancement. This composite provides an efficient and eco-friendly approach for tetracycline antibiotic pollution control in aqueous environments. Full article