Molecular monitoring, identification of the microcystin synthetase (mcy) gene and toxic potential of Microcystis aeruginosa in Indian freshwater blooms.

Enantioselective toxicity of 3,4-methylenedioxypyrovalerone in Daphnia magna: Assessment of morphophysiological, behavioural, biochemical and reproductive responses.

Pyridaben-induced biochemical and molecular stress in Daphnia magna.

DaphTrack: A deep learning-based multidimensional behavior analysis system for neonatal Daphnia magna.

Comparative study on the reproduction toxicity of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) to Daphnia magna based on a 21-day short-term exposure and whole-life-stage exposure and the underlying toxic mechanisms.

Unveiling the overlooked environmental risks of organic flotation reagents: Intergenerational toxicity of potassium ethylxanthate to Daphnia magna.

Unveiling p-phenylenediamine rubber antioxidants as precursors of disinfection byproducts: Kinetics, formation, and toxicity.

Comparing the toxicity of nitrate between different species of subterranean Niphargus amphipods.

Serving as a staple food for over half of the world population, rice plants tend to accumulate higher levels of cadmium (Cd) and arsenic (As) than other cereal crops. Copper...

Significantly enhanced effects of heavy metals on the toxicity, bioconcentration and biomagnification under combined exposure.

In this study, the ecological toxicity of three substitute perfluoroalkyl substances (PFBA, PFBS, PFHxA) was measured through acute and chronic toxicity tests using <i>Daphnia magna</i>, a representative species of aquatic organisms. The result of this study indicated that the acute toxicity of PFBA and PFBS for <i>D. magna</i> were 25 times and 111 times lower, respectively, than those of PFOA and PFOS. Similarly, the chronic toxicity of PFBA and PFBS for <i>D. magna</i> were 126 times and 397 times lower, respectively, than those of PFOA and PFOS. Therefore, the ecological toxicity of the substitute perfluoroalkyl substances to <i>D. magna</i> seems to be significantly lower than that of PFOA and PFOS. Meanwhile, in this study, the acute toxicity of PFHxA (six carbon substance) was approximately 11 times lower than that of PFOA (eight carbon substance), but about two times higher than that of PFBA (four carbon substance). This finding suggest that the ecological toxicity of perfluoroalkyl substances decreases as the carbon chain length decreases. In addition, the ratio of acute to chronic toxicity (ACR) for PFBA and PFBS (both four carbon substance) showed about a two-fold difference, indicating that, among perfluoroalkyl substances with the same number of carbon atoms, those with a sulfonic acid group (e. g. PFBS) exhibit higher toxicity than those with a carboxylic acid group (e.g PFBA). Although the tested substitute perfluoroalkyl substances showed lower toxicity to <i>D. magna</i> compared to conventional PFOA and PFOS, they are still not easily removed in wastewater treatment processes and do not readily degrade in the natural environment. Therefore, if the usage of these substitute perfluoroalkyl substances increases, their concentration in the environment is expected to rise. Consequently, further research is necessary to assess long-term exposure and its potential impact on ecosystems due to these substitute perfluoroalkyl substances.

This study examines the effects of heavy metal cations (Cu2+, Fe2+, Pb2+, Zn2+, Cd2+, Ni2+) and their binary mixes on lesser duckweed (Lemna minor) and Daphnia magna. Standardized bioassay methods with concentrations that are multiples of the maximum permissible concentrations (MPC) are used. Cadmium was the most harmful to L. minor (ED50 = 0.25 mg/L), whereas nickel was the least hazardous (ED50 = 5.0 mg/L). Copper was most harmful to D. magna (ED50 = 0.11 mg/L), whereas nickel was the least toxic (ED50 = 5.0 mg/L). Binary mixture analysis showed synergy (CI < 1) at low concentrations (1 10 MPC) and antagonism (CI > 1) at high concentrations (100–1000 MPC), which were linked to increased oxidative stress and competition for binding sites. Daphnia magna locomotor activity demonstrated to be a sensitive indicator of sublethal metal exposure and is appropriate for early toxicity diagnosis. The results validate species-specific sensitivity variations and highlight the significance of an integrated approach to ecological risk assessment in aquatic environments contaminated with heavy metals and combinations

This study aimed to determine the ecotoxicological effects of polyvinyl chloride (PVC) microplastics on Daphnia magna. Five experimental groups were estab-lished. These were the microplastic group (MP), the microalgae group (Chlorella sorokiniana, KS), the combined microalgae and microplastic group (KS+MP), the commercial yeast group (Saccharomyces cerevisiae, TM), and the combined yeast and microplastic group (TM+MP). The exposure period lasted for 21 days. Survival, growth, and reproductive parameters were evaluated. The highest mortality rate was recorded in the MP group with 86.7%, followed by the TM+MP group with 70%. The mortality rates in the KS, TM, and KS+MP groups were 3.3%, 10%, and 56.7%, respectively. Microplastic exposure significantly reduced body length. On day 21, the mean body length was 1.76 mm in the MP group and 3.14 mm in the KS group. The number of eggs and offspring markedly decreased in all micro-plastic-exposed groups, with the lowest reproductive success observed in the MP group. Diets containing microalgae partially mitigated toxicity, though this effect diminished under chronic exposure. The findings indicate that mi-croplastics cause both physical blockage and physiological stress, adversely affecting the growth, reproduction, and lifespan of Daphnia magna, posing a significant eco-logical risk to freshwater ecosystems.

Nanoplastics pose significant environmental and public health risks, prompting the need for sensitive, cost-effective, and rapid assays for ecotoxicity assessment. The present work proposes the use of a portable smartphone-based platform to enhance traditional Daphnia magna acute toxicity assays by integrating behavior analysis and heart rate measurements. The aim is to improve sensitivity in detecting toxic effects of nanoplastics. In particular, the study focused on nano-sized carboxylated polystyrene (PS) nanoparticles. Two variability factors that could influence biological effects of nanoplastics, the particle size and the age of the organisms, were considered. Results demonstrated that the application of the proposed integrated approach allowed the detection of early subtle effects such as a significant impact on the heart rate and behavior of Daphnia magna under short-term exposure to PS carboxylated nanoparticles. In particular, a stimulation of heart rate was observed for both neonates and adults either for 40 nm or 200 nm particles after 48 h exposure, presumably attributable to an interference of carboxylated PS NPs with adrenergic-type receptors. Behavioral alterations were detectable for 40 nm particles but not for 200 nm ones consisting of a decrease in velocity and alterations of trajectories. Obtained results demonstrated the suitability of the proposed smartphone platform for friendly and real-time integration of behavioral analysis with physiological outcome measurements during acute exposure of Daphnia magna to nano-sized carboxylated PS NPs, expanding the sensitivity of the traditional acute toxicity tests. It offers a novel, cost-effective, and field-applicable method for environmental monitoring of nanoparticle toxicity and impact.

Objective: The objective of our study was to synthesize and characterize silica–copper nanomaterials and to evaluate their biological properties (antibacterial, redox, cytotoxic, and ecotoxic) for potential applications. Methods and Results: Si/Cu-based materials were prepared by a sol–gel method. They were characterized by XRD, UV-Vis, and SEM-EDS. The antibacterial activity of the materials was evaluated against Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium), and yeasts (Candida albicans, Saccharomyces cerevisiae). The nanomaterial that was calcined at 500 °C exhibited greater antibacterial efficacy compared to the gel form. S. typhimurium demonstrated the highest susceptibility, whereas S. aureus and P. aeruginosa were the most resistant of the tested bacteria. Both yeasts exhibited comparable sensitivity (MBC = 1.0 mg/mL). The redox activity of both nanomaterials was tested at pH 7.4 (physiological) and 8.5 (optimal) by the activated chemiluminescent method. The nanocomposites significantly inhibited the free-radical and ROS generation. This presents them as redox regulators in living systems. The cytotoxic effects in normal BEAS-2B and tumor A549 human cell lines were assessed microscopically and by the cell viability neutral red uptake assay, CC50 being evaluated. The observed effects suggest moderate, similar cytotoxicity in both cell lines. The ecotoxicity study using Daphnia magna showed an LC50 of ~7–8 mg/L about Si/Cu/500. The LC50 for Si/Cu (gel) was lower than 0.25 mg/L, indicating an increase in toxicity with increased exposure time. Conclusions: Possible applications of the newly synthesized nanomaterials include antimicrobial coatings, drug delivery systems, antioxidant additives in various formulations, and water purification.

Although the importance of transgenerational effects and multiple stressors in ecotoxicology is well-established, transgenerational interactions between toxicants and natural stressors remain largely unexplored, yet are critical for advancing ecological risk assessment. In this study, we exposed the water flea Daphnia magna to a heat spike (25 °C vs 32 °C) followed by exposure to chlorpyrifos at an environmentally relevant concentration (0.5 μg/L) across the parental and grand-offspring generations using a full-factorial design. In both generations, chlorpyrifos reduced survival and acute heat tolerance, which, as expected, were further magnified by the preceding heat spike. Notably, parental exposure to chlorpyrifos decreased the sensitivity of grand-offspring to the toxicant, and more strikingly, offset the synergistic interaction between the heat spike and chlorpyrifos. Both the increased toxicity of the pesticide after exposure to the heat spike and the mitigating impact of the transgenerational effects on this synergism could be explained by changes in acetylcholinesterase activity and hemoglobin concentration. These findings underscore the critical role of transgenerational effects in ecotoxicology, including their potential to shape toxicant-warming interactions. Our results emphasize the necessity of incorporating transgenerational effects and multistressor scenarios into ecological risk assessments of toxicants in the context of global warming.

This study investigates the synthesis and potential applications of the coordination compound cobalt(III) complex tris[N-(prop-2-en-1-yl)hydrazinecarbothioamide]-cobalt(III) chloride ([Co(Tsc)3]Cl3). The complex has been synthesized via the reaction of cobalt(II) chloride hexahydrate with N-(prop-2-en-1-yl)hydrazinecarbothioamide in ethanol. Its antioxidant activity has been evaluated using 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, demonstrating a significant effect with an IC50 of 7.3 µmol/L. Toxicity evaluations using Daphnia magna showed a low half maximal inhibitory concentration (LC50) of 56.3 µmol/L. Experimental results have showed that [Co(Tsc)3]Cl3 significantly elevated the total antioxidant status (TAS) of the hemolymph of honeybees and larvae, increasing it by 5 and 8 times, respectively. The IC50 values for antioxidant activity were 2.5 mg/mL in bee hemolymph and 1.3 mg/mL in larval hemolymph, notably lower than control values of 13.6 mg/mL and 10.0 mg/mL. The stimulatory effect of the coordination compound [Co(Tsc)3]Cl3 on TAS was five times higher than that of vitamin C. Additionally, [Co(Tsc)3]Cl3 exhibited acaricidal properties, effectively inhibiting Varroa destructor with an lethal concentration (LC50) of 0.2 µmol/L. These findings indicate that this cobalt complex could serve both a natural antioxidant and an effective acaricide, offering a promising approach to improv bee health and sustainability in apiculture.

The toxicity of mercury sulfide nanoparticles (HgS-NPs) is likely mediated by their in vivo dissolution into bioavailable Hg2+. However, tracking this transformation within complex biological systems has been a major analytical challenge, hindering a mechanistic understanding of the HgS-NPs' toxicology. To address this, we developed an aggregation-induced emission (AIE)-based bioimaging technique for the selective and real-time monitoring of Hg2+ in Daphnia magna, enabling the direct visualization and quantification of HgS-NP dissolution in a multicellular organism. Our Hg2+-specific AIE probe exhibited a detection limit of 0.52 ng/mL and negligible toxicity at working concentrations. Using this method, we directly visualized and quantified the time-dependent dissolution of ingested HgS-NPs of different sizes (20 and 60 nm). We found that the gut region was the primary site of Hg2+ accumulation, with a region-specific distribution showing significantly higher concentrations in the foregut than the hindgut. At dissolution equilibrium, 8.4% of the ingested 20 nm HgS-NPs and 4.9% of the 60 nm NPs were transformed into Hg2+. Furthermore, by correlating with pH mapping, we demonstrated that the extent of HgS-NPs dissolution is negatively correlated with the local pH in the gut. This study provides crucial insights into the biotransformation of HgS-NPs in a model aquatic organism, fundamentally challenging the paradigm of their environmental inertness. Our findings highlight the gut as a critical bioreactor for the transformation of low-solubility metal sulfides, with significant implications for accurately assessing their bioavailability and ecological risks.

Microplastic pollution is a growing global concern with direct and indirect environmental health impacts. Africa hosts some of the most heavily polluted water bodies, exacerbated by limited management resources and research capacities. To evaluate the state-of-the-art in African freshwater microplastics approaches, we review studies that assessed pollution in freshwater organisms and appraise the field sampling and laboratory techniques used. Thirty-seven studies were included that analysed the status of microplastic concentration, ingestion, and abundance in African freshwater organisms. Of these, 11 studies conducted experimental work in laboratory settings, whereas the remainder were field-based. Studies were biased taxonomically and geographically, with 24 on fish, 10 on macroinvertebrates, and one each on birds and amphibians, and with studies predominantly in a few countries, mainly South Africa. Most of the studies were thus conducted in southern Africa, followed by east Africa, finding fibres to be the most dominant microplastic type, followed by fragments. Laboratory studies predominantly used pellets, polystyrene microbeads, polyethylene, polypropylene, polyvinyl chloride, nylon 66, and polyethylene terephthalate to determine their impact on organisms such as Clarias gariepinus, Oreochromis niloticus, Tilapia sparrmanii, Daphnia magna, Raphidocelis subcapitata and Tetrahymena thermophila. Microplastic extraction and separation from fish and aquatic macroinvertebrates are mostly done using potassium hydroxide (KOH), hydrogen peroxide (H2O2), nitric acid (HNO3) and sodium hydroxide (NaOH). Furthermore, instrumental analytical techniques for microplastics included the use of microscopes and Fourier-transform infrared (FT-IR) or attenuated total reflectance-Fourier transform infrared spectroscopy for polymer verification. Although Africa ranks highly in unmanaged plastic waste, studies on the prevalence of freshwater microplastics and their interactions with freshwater organisms in natural ecosystems remain scarce. Therefore, it is recommended that more studies are conducted to address the substantial gap, given the importance of freshwater biota in biomonitoring, especially in countries with a complete absence of studies on freshwater microplastic pollution.

Acute toxicity of novel triazine-based UV filters towards Chlorella vulgaris and Daphnia magna: Single and mixture effect.