Search Results (272)

Olive mill wastewaters (OMWWs) are an environmental problem in the Mediterranean region, and it is crucial to explore strategies for their treatment and repurposing. The chemical precipitation technique (CPT) has been presented as a cost-effective wastewater treatment solution that might be applied to OMWW. The CPT-resulting precipitant subproducts (sludge) may be reprocessed (e.g., agricultural fertilizer and/or soil amendment), while the treated wastewater may be repurposed or reused (e.g., irrigation, aquaponic, or industrial processes). This study aimed to evaluate the efficacy of CPT in treating wastewater from the olive oil industry from an ecotoxicological perspective. Additionally, to assess the safe use of the obtained sludge in CPT treatment, its effects on soil biota were assessed. For this, a set of ecotoxicological assays using freshwater (Raphidocelis subcapitata, Daphnia magna and Danio rerio), terrestrial invertebrates (Folsomia candida and Enchytraeus crypticus), and plants (Brassica oleracea and Lolium perenne) were used as model organisms. Results demonstrated that CPT reduced OMWW toxicity to freshwater organisms, offering a favorable outlook on CPT’s potential as a wastewater treatment method. Increasing application rates of sludge in soil reduced the shoot biomass and the hydric content of both plants compared to the control. Survival of F. candida and E. crypticus was not affected by sludge in soil at any tested application rate, yet sludge application negatively affected the reproduction of both species, even at relevant sludge application rates (2%) of sludge in soils. Overall, the applicability of this sludge obtained by the CPT treatment in soils should be carefully evaluated due to the observed adverse effects on soil biota. Although the results of CPT were promising in reducing the toxicity of OMWW for these aquatic species, some adjustments/improvements should be performed to improve this technique and use all the obtained resources (treated water and sludge) in a fully circular perspective. Full article

In this study, Sr_0.95Bi_0.05TiO₃ was synthesized via solid state reaction, characterized, and applied as a visible-light-active photocatalyst for the degradation of oxytetracycline, imidacloprid, and their mixture. To evaluate the influence of the aqueous matrix on pollutant degradation, photocatalytic experiments were carried out in both distilled water and a real environmental sample (surface water). The Sr_0.95Bi_0.05TiO₃ perovskite showed high photocatalytic performance under visible light, achieving nearly complete degradation of oxytetracycline after 2 h, and significant removal of imidacloprid in river water (60% after 3 h). Enhanced degradation in surface water was attributed to favorable ionic composition and pH. The perovskite oxide maintained its photocatalytic performance over five consecutive cycles, with no significant loss in photocatalytic activity or structural and morphological stability. Ecotoxicological assessment using Daphnia magna confirmed that the treated water was non-toxic, indicating that no harmful byproducts were formed. Complementary Density Functional Theory calculations were conducted to complement experimental findings, providing insights into the structural, electronic, and optical properties of the photocatalyst, enhancing the understanding of the degradation mechanisms involved. This integrated approach, combining experimental photocatalytic performance evaluation in different matrices, ecotoxicity testing, and theoretical modeling, highlights Sr_0.95Bi_0.05TiO₃ as a promising, stable, and environmentally safe photocatalyst for practical wastewater treatment applications. Full article

Pharmaceuticals such as fluoxetine, paroxetine, sertraline, and mianserin occur in aquatic environments at low yet persistent concentrations due to their incomplete removal in wastewater treatment plants. Although frequently detected, these neuroactive compounds remain underrepresented in ecotoxicological assessments. Given their pharmacodynamic potency, environmentally relevant concentrations may induce sublethal effects in non-target organisms. In this study, we applied untargeted LC-MS-based metabolomics to investigate the sublethal effects of four widely used antidepressants—paroxetine, sertraline, fluoxetine (SSRIs), and mianserin (TeCA)—on two ecologically relevant freshwater invertebrates: S. ambiguum and D. magna. Organisms were individually exposed to each compound for 48 h at a concentration of 100 µg/L and 25 µg/L, respectively. Untargeted metabolomics captured the sublethal biochemical effects of these antidepressants, revealing both shared disruptions—e.g., in glycerophospholipid metabolism and cysteine and methionine metabolism—and species-specific responses. More pronounced pathway changes observed in D. magna suggest interspecies differences in metabolic capacity or xenobiotic processing mechanisms between taxa. Among the four antidepressants tested, sertraline in D. magna and fluoxetine in S. ambiguum exerted the most extensive metabolomic perturbations, as evidenced by the highest number and pathway impact scores. In D. magna, fluoxetine and mianserin produced similar metabolic profiles, largely overlapping with those of sertraline, whereas paroxetine affected only a single pathway, indicating minimal impact. In S. ambiguum, paroxetine and mianserin elicited comparable responses, also overlapping with those of fluoxetine, while sertraline triggered the fewest changes. These results suggest both compound-specific effects and a conserved metabolic response pattern among the antidepressants used. They also underscore the considerable potential of metabolomics as a powerful and sensitive tool for ecotoxicological risk assessments, particularly when applied across multiple model organisms to capture interspecies variations. However, further research is essential to identify which specific pathway disruptions are most predictive of adverse effects on organismal health. Full article

The increasing release of nanoparticles into aquatic environments, particularly via wastewater, raises concerns about their biological effects on microbial communities. This study investigated the molecular response of Pseudomonas putida to aluminum oxide nanoparticles (Al₂O₃NPs) under controlled conditions and in synthetic wastewater, both before and after biological treatment. Acute toxicity was evaluated using growth inhibition assays, while the expression of katE, ahpC, and ctaD—genes associated with oxidative stress and energy metabolism—was quantified via RT-qPCR. Exposure to pristine Al₂O₃NPs induced a strong, time-dependent upregulation of all tested genes (e.g., katE and ahpC up to 4.5-fold). In untreated wastewater, this effect persisted but at a lower intensity; bulk Al₂O₃ caused only moderate changes. Treated wastewater samples showed markedly reduced gene expression, indicating partial detoxification. Nanoparticles elicited stronger biological responses than their bulk counterparts, confirming the material form-specific effects. Comparative analysis with Daphnia magna revealed similar patterns of oxidative stress gene activation. These findings highlight the influence of nanoparticle form and environmental matrix on microbial responses and support the use of gene expression analysis as a sensitive biomarker for nanoparticle-induced stress in environmental risk assessment. Full article

The crustacean Daphnia magna produces genetically identical females and males by parthenogenesis. Males are produced in response to environmental cues including crowding and lack of food. For male development, the DM-domain containing transcription factor Doublesex1 (DSX1) is expressed spatiotemporally in male-specific traits and orchestrates male trait formation in both somatic and gonadal tissues. However, it remains unknown how the dsx1 gene is silenced in females to avoid male trait development. Heterochromatin Protein 1 (HP1) plays a crucial role in epigenetic gene silencing during developmental processes. Here we report the identification of four HP1 orthologs in D. magna. None of these orthologs exhibited sexually dimorphic expression, and among them, HP1-1 was most abundantly expressed during embryogenesis. The knock-down of HP1-1 in female embryos led to the derepression of dsx1 in the male-specific traits, resulting in the development of male characteristics, such as the elongation of the first antennae. These results suggest that HP1-1 silences dsx1 for female development while environmental cues unlock this silencing to induce male production. We infer the HP1-dependent formation of a sex-specific chromatin structure on the dsx1 locus is a key process in the environmental sex determination of D. magna. Full article

Background: The present work is devoted to the biological effects of sol–gel-derived silica (Si)–copper (Cu) nanomaterials. Methods and Results: Tetraethyl orthosilane (TEOS) was used as a silica precursor; copper was introduced as a solution in ethanol with Cu(OH)₂. The obtained samples were denoted as Si/Cu (gel) and Si/Cu/500 (500 °C heat-treated). Their phase formation and morphology were studied by XRD and SEM. The antibacterial activity was tested by two Gram-positive bacteria, three Gram-negative bacteria, and two types of eukaryotic species. Most bacteria were more sensitive to Si/Cu/500 materials than to Si/Cu (gel). The yeasts were more sensitive to Si/Cu (gel). The new nanomaterials were tested for oxidant activity at pH 7.4 (physiological) and pH 8.5 (optimal) in three model systems by the chemiluminescent method. They significantly inhibited the generation of free radicals and ROS. This result underlines their potential as regulators of the free radical processes in living systems. The epithelial tumor cell lines appeared more sensitive than the non-transformed fibroblasts, likely due to their metabolic activity and proliferation rates, leading to greater accumulation of the substances. Using Daphnia magna, the ecotoxicity study showed that the LC₅₀ was reached at 1 mg/L of Si/Cu/500. Si/Cu (gel) was more toxic. Conclusions: Our results reveal the potential of these nanohybrids to be applied in living, eukaryotic systems. The cytotoxicity evaluation showed higher tolerance of normal, non-transformed cells, in concurrence with the oxidation tests. Full article

The widespread use and pseudo-persistent occurrence of the antidepressant citalopram (CIT) could pose a potential ecological risk in the aquatic environment. The message about the bioconcentration and sensitive biomarker identification of CIT at the environmentally relevant concentrations is limited. In this study, an integral evaluation of the phenotypic and biochemical effects of CIT on Daphnia magna (D. magna) was conducted at 0.5 and 10 µg/L. The biomarker screening includes energy metabolism, phototactic behavior, feeding dysfunction, and antioxidant stress responses. The carbohydrate, lipid, and protein content was determined using the assay of anthrone with glucose as standard, thiophosphorate-Vaniline with cholesterol as standard, and Coomassie brilliant blue with serum albumin as standard, respectively. The results showed the bioconcentration equilibrium of CIT reached at the exposure duration of 48 h during the uptake process. At the exposure concentrations of 0.5 and 10 µg/L, the bioconcentration factor of CIT was 571.2 and 67.4 L/kg, respectively. Both protein and lipid content significantly increased at 0.5 µg/L with a 1.78-fold elevation in total energy. Comparatively, the lipid content showed a significant increase at 10 µg/L, while the available total energy rose by 1.25-fold relative to the control group. The phototactic behavior of D. magna exposed to 0.5 µg/L CIT was markedly reduced at 48 h relative to control. In contrast, a significant decrease in phototaxis was observed after 6 h and then a significant increase at 12 h with a continuously obvious decline at 10 µg/L. The filtration rates were increased by 32% compared to controls at 0.5 µg/L, while the stimulatory effects disappeared at 10 µg/L. With regarding to the antioxidant enzyme activities, CIT exposure significantly inhibited the catalase activity both at 0.5 and 10 µg/L, while the glutathione S-transferase activity was obviously induced at 0.5 µg/L and inhibited at 10 µg/L. The expression level of 18s gene was significantly decreased at 10 µg/L. Only the gst gene expression level was significantly increased at 0.5 µg/L, while the 18s and cat gene expression level was obviously inhibited and induced at 10 µg/L. Comprehensively, the responses of the phenotypic traits and energy metabolism of D. magna at various environmental concentrations were sensitive for CIT. This study provided basic data for the risk estimation of CIT in the real freshwater environment. Full article

This study explores the interaction between Prymnesium parvum and Daphnia magna under low-salinity conditions. P. parvum showed reduced growth below 0.4 PSU and peaked at 1.0 PSU within the tested 0.2–1.0 PSU range. D. magna, exposed to P. parvum across 0.0–6.0 PSU, experienced increased mortality at 4.0 and 6.0 PSU, but tolerated 0.0–1.0 PSU well and grazed actively on P. parvum without significant vitality loss. This range reflects conditions observed in the Oder River during the 2022 fish die-off. The count of P. parvum cells did not vary significantly across the 0.2 to 1.0 PSU range of salinities in D. magna presence, except at 0.6 PSU. All daphnids survived even at P. parvum densities of 1 × 10⁵ cells/mL, though increasing algal concentrations reduced juvenile growth rates. Direct observation under a microscope confirmed algal ingestion. Toxin accumulation in cells and medium likely reduced grazing efficiency via allelopathic effects. The study assessed whether D. magna can tolerate prymnesins while maintaining feeding under varying salinities. Results suggest that Daphnia magna could act as a biological suppressor of golden algae under certain environmental conditions, though further work is needed to quantify grazing efficiency and prymnesins concentrations. Full article

The widespread availability and pseudo-persistence of typical psychiatric pharmaceuticals (PDs) can have serious impacts on aquatic ecosystems and even human health. However, the toxicokinetics of typical PDs and the corresponding enzymatic biomarker responses are unclear. In this study, eight typical PDs [carbamazepine (CBZ), citalopram (CIT), sertraline (SER), venlafaxine (VLF), amitriptyline (AMT), chlorpromazine (CPM), quetiapine (QTP) and clozapine (CLZ)] were selected to study the uptake, depuration and biological effects of PDs in Daphnia magna. The results found that the uptake rates (K_u) were in the sequence of VLF < QTP < CBZ < CLZ < CIT < AMT < SER < CPM, while the depuration rates (K_d) were in the order of CLZ < AMT < CIT < SER < QTP < CBZ < CPM < VLF. Correspondingly, the bioconcentration factors (BCFs) followed on as VLF < QTP < CBZ < CIT < AMT < CLZ < SER < CPM. Both pH-dependent octanol–water partition coefficients (log D_ow) and liposome–water partition coefficients (log D_lip-w) exhibited positive correlations with the log BCF of PDs (p < 0.05), indicating the important roles of ionization degree and biological phospholipid contents on bioconcentration. Superoxide dismutase (SOD) activities were evidently induced in the SER and CPM groups, while ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) activities were significantly induced only in the CBZ group. Acetylcholinesterase (AChE) activity was obviously induced by CBZ, SER and AMT, with levels 1.73, 1.62 and 2.44 times that of the control group (p < 0.05). The K_u of PDs, oxidative stress and metabolic level of D. magna combine to affect BCF levels together. In conclusion, this study contributes to a better understanding of the toxicokinetics and biochemical responses of PDs in D. magna and potential mechanisms of action, which may allow for a better assessment of their environmental health risks to aquatic ecosystems. Full article

Freshwater cyanobacterial harmful algal blooms (FCHABs) alter zooplankton communities, often adversely, through the production of cyanotoxins. While Daphnia magna is frequently used to evaluate the impact of toxicants, it is not commonly found in tropical waters; cladocerans from tropical and subtropical waterbodies should be used in bioassays. Here, we evaluated the impact of crude cyanobacteria extracts on three common, native species (Daphnia laevis, Ceriodaphnia dubia, and Simocephalus vetulus) based on acute and chronic bioassays. We analyzed the toxicity of cyanobacterial consortium collected from Lake Zumpango, Mexico. The FCHAB was dominated by Planktothrix agardhii (1.16 × 10⁶ ind mL⁻¹). A series of freeze/thaw/sonification cycles at 20 kHz was used to extract the toxic metabolites and the concentration of dissolved microcystin-LR equivalents was measured using an ELISA immunological kit. S. vetulus was the most sensitive species, with a median lethal concentration of 0.43 compared to 1.19 µg L⁻¹ of D. magna at 48 h. S. vetulus was also the most sensitive in chronic evaluations, showing a negative rate of population increase (−0.10 d⁻¹) in experiments with 20% crude extract. Full article

Improving the aqueous solubility of poorly soluble pharmaceuticals is essential for accurate pharmacotoxicological testing, but the biological safety of solubilizers and hydrotropic agents used for this purpose requires careful evaluation. This study assessed the acute toxicity, physiological parameters (heart rate, claw and appendage movement), behavioral responses (swimming speed), and embryotoxicity of 15 commonly used solubilizers and hydrotropes using Daphnia magna as a biological model. Compounds included surfactants (polysorbate 20 (Tween 20), polysorbate 80 (Tween 80), sodium lauryl sulfate (SLS)), sulfonated hydrotropes (sodium xylene sulfonate (SXS), sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (PTS), sodium 1,3-benzenedisulfonate (SBDS)), and solubilizing solvents (dimethyl sulfoxide (DMSO), glycerol (GLY), propylene glycol (PDO), dimethylformamide (DMF), N,N’-Dimethylbenzamide (DMBA), N,N-Diethylnicotinamide (DENA), N,N-Dimethylurea (DMU), urea). Acute lethality was evaluated across concentration ranges appropriate to each compound group (e.g., 0.0005–0.125% for surfactants; up to 5% for less toxic solvents). Surfactants exhibited extreme toxicity, with Tween 20 and SLS causing 100% lethality even at 0.0005%, while Tween 80 induced 40–50% lethality at that concentration. In contrast, DMSO, GLY, and PDO showed low acute toxicity, maintaining normal heart rate (202–395 bpm), claw and appendage movement, and swimming speed at ≤1%, though embryotoxicity became evident at higher concentrations (≥1–2%). SXS, SBS, PTS, and SBDS displayed clear dose-dependent toxicity but were generally tolerated up to 0.05%. DMBA, DENA, and DMU caused physiological suppression, including reduced heart rate (e.g., DMBA: 246 bpm vs. control 315 bpm) and impaired mobility. Behavioral assays revealed biphasic effects for DMSO and DMBA, with early stimulation (24 h) followed by inhibition (48 h). Embryotoxicity assays demonstrated significant morphological abnormalities and developmental delays at elevated concentrations, especially for DMSO, GLY, and PDO. Overall, DMSO, GLY, PDO, SXS, and DMF can be safely used at tightly controlled concentrations in Daphnia magna toxicity assays to ensure accurate screening without solvent-induced artifacts. Full article

The growing need for sustainable protein sources in aquaculture has led to interest in microalgae, such as Chlorella vulgaris, known for its high nutritional value. One promising strategy for delivering these nutrients is through bioencapsulation in Daphnia magna, a common live feed used in aquaculture. This study evaluated the effect of including D. magna bioencapsulated with C. vulgaris as live feed for marine shrimp Penaeus vannamei post-larvae. Shrimp were fed at two D. magna densities (5 and 10 per shrimp, 5DF and 10DF), offered weekly, and compared with a control group receiving only commercial feed (F) for 36 days in a synbiotic nursery system. Water quality, zootechnical performance, protein, and lipid content of the shrimp were analyzed using correlation analyses, nonlinear prediction models, and principal component analysis (PCA). Shrimp fed with the 10DF treatment exhibited superior zootechnical performance, characterized by a lower feed conversion ratio (1.01) and higher feed efficiency (99.97%), protein (70.91%), and lipid (32.45%) content in comparison with the 5DF and control. Quadratic regression predictive models indicated the possibility of further testing higher concentrations of D. magna per shrimp. The results indicates that the use of C. vulgaris bioencapsulated in D. magna as live feed for P. vannamei is a promising approach to improve shrimp diets and increase production in aquaculture. Full article

The agricultural production process contributes to the global issue of pesticide pollution. Based on the static toxicity test of diuron (DCMU) on Daphnia magna (D. magna) for EC₅₀-48 h, a concentration range of 0.2 to 1 mg/L was set as sublethal concentrations, while lethal concentrations were set at 2 mg/L and 4 mg/L. This study analyzes the toxic response patterns of the swimming behavior indicators of D. magna exposed to different concentrations of DCMU. The results showed that the average speed (V) of D. magna decreased step by step with exposure time, regardless of exposure to sublethal concentration or lethal concentration. However, during the same short-term exposure period, the V of D. magna at lethal concentration was higher than that at sublethal concentration, which indicates that the swimming behavior of D. magna exposed to DCMU may be stimulated and accelerated. Compared to the control group, there is a statistically significant difference in the V of D. magna after short-term exposure, especially showing an extremely significant difference after 5 min of exposure. Evidently, compared to the traditional 48 h static toxicity testing method, the swimming behavior indicators of D. magna show a more sensitive response to DCMU after 5 min of exposure, making it more suitable for rapid toxicity detection. By expanding the range of exposure concentrations, it was found that the V indicator of D. magna responded significantly to a DCMU concentration of 0.05 mg/L after only 5 min of exposure, and a high degree of correlation was observed between the indicator and the exposure concentration. Through nonlinear fitting, the relationship between V and the dose–effect of DCMU toxicity presents an S-shaped curve, with R² > 0.9. Consequently, it becomes possible to study the dose–effect relationship between the changes in the swimming behavior indicators of D. magna and the stress concentration based on this theory. This further establishes a foundation for the development of comprehensive aquatic toxicity rapid detection technology based on the toxic response of swimming behavior indicators. Full article

Catechins, renowned for their health benefits, have unexamined environmental impacts. This study assessed the toxicity of crude catechin and catechin hydrate on invertebrate larvae, plant, and microalgae. The survival rates of Daphnia magna Straus and Artemia salina L. were monitored every 24 h over a three-day period. The germination rate and radicle length of Lactuca sativa L. was measured every 24 h for four days. Inhibitory effects were evaluated in both freshwater and seawater cultures of Chlorella vulgaris Beijerinck, with cell density recorded every 24 h and yield inhibition calculated after 96 h. Results indicated that increasing catechin concentration and exposure duration decreased the survival rate of D. magna and A. salina. Daphnia magna was more sensitive to catechins than A. salina, with 24 h lethal concentration 50 (LC-50) values of 1174 µg/mL compared to 1895 µg/mL for crude catechin, and 54 µg/mL compared to 153 µg/mL for catechin hydrate. The germination rate and radicle length of L. sativa, along with the cell density of C. vulgaris, decreased with increasing catechin concentration, but remained higher even after prolonged exposure. At low catechin concentrations, C. vulgaris cell density exceeded control levels. This study demonstrates that catechins in aquatic environments can significantly impact ecosystems. At certain concentrations, catechins are toxic and potentially lethal to aquatic organisms. Conversely, at lower concentrations, catechins may promote microalgal growth, suggesting a fertilizing effect. Understanding these dynamics is crucial for maintaining the stability of aquatic ecosystems. Full article

Micro- and nanoplastic pollutants are among the major environmental challenges, and are exacerbated by the continuous degradation of growing amounts of plastic debris in the aquatic environment. The purpose of this study was to investigate the morphology of micro/nanoplastics (M/NPs) formed from polyethylene terephthalate (PET) by mechanical degradation in an aquatic environment, which mimics the processes in the natural environment well, and to determine the impact of these particles on model aquatic organisms. To this end, M/NPs were obtained by ball milling in an aqueous medium and the effect of milling length on particle size and shape was investigated. The particles obtained in an environment simulating natural conditions were irregularly shaped, and those of nanometric size tended to form aggregates of various shapes. The ingestion and toxicity of PET M/NPs to freshwater zooplankton were then assessed. Daphnia magna and Thamnocephalus platyurus were used in a series of acute ecotoxicity tests, by exposure to M/NP dispersions at environmentally realistic concentrations (0.01–1.0 mg/L), as well as at very high concentrations (100–1000 mg/L). A significant uptake of PET particles by both types of invertebrates was observed, and the M/NPs were mainly concentrated in the digestive tracts of the crustaceans. However, they did not cause acute toxicity to the tested organisms or a reduction in their swimming activity, even at concentrations as high as 1000 mg/L. Full article