•Lyocell, polyester, and polypropylene microfibers found to be toxic.•Natural microfiber (lyocell) more toxic to D. magna than synthetics (PP and PET).•Toxic effects of microfibers (natural and ...synthetic) persist after exposure ceases.•Contrast in effects of microfiber exposure to food uptake and growth in D. magna.•Growth stunting and gut damage from natural and synthetic microfiber exposure.
Microfibers, which are sourced from textiles and some products from the fishery industry, are the biggest contributors to microplastic pollution in aquatic ecosystems. In addition to these synthetic microfibers, naturally derived microfibers can also be found in aquatic environments. However, there are limited studies on the ecotoxicity of natural microfibers. To shed light on this topic, this study assessed and compared the toxicity of natural and synthetic microfibers on Daphnia magna, using lyocell, polyester (PET) and polypropylene (PP) microfibers. To evaluate the adverse effect of microfibers on D. magna, after effects including depuration, food intake, growth, mortality, and immobilization rate were continually observed for up to 96 h after the initial 48 h of exposure to the microfibers. Immobilization rate decreased in the following order: PP, PET, and lyocell. However, the depuration of microfibers in the lyocell and PET treatment groups was similar, with higher mortality rates than in the PP treatment group. Furthermore, despite the high rates of food intake following exposure, the lyocell and PET exposed groups exhibited growth inhibition during the same period. This growth inhibition corresponded with, and was likely due to, reductions in the length of gut microvilli, probably an expression of gut damage, which is believed to have reduced nutrient absorption in the affected individuals. Based on the results of this study, it was confirmed that even natural microfibers, and not just synthetic microfibers, can have adverse effects on aquatic organisms. This study confirmed not only the toxicity of microfibers, but also the consequences of their after effects. These results could be the basis for future research on the after effects of microplastics on aquatic organisms and provide directions for further microplastic ecotoxicity studies.
Contamination of fine plastic particles (FPs), including micrometer to millimeter plastics (MPs) and nanometer plastics (NPs), in the environment has caught great concerns. FPs are strong adsorbents ...for hydrophobic toxic pollutants and may affect their fate and toxicity in the environment; however, such information is still rare. We studied joint toxicity of FPs with phenanthrene to Daphnia magna and effects of FPs on the environmental fate and bioaccumulation of 14C-phenanthrene in fresh water. Within the five sizes particles we tested (from 50 nm to 10 μm), 50-nm NPs showed significant toxicity and physical damage to D. magna. The joint toxicity of 50-nm NPs and phenanthrene to D. magna showed an additive effect. During a 14-days incubation, the presence of NPs significantly enhanced bioaccumulation of phenanthrene-derived residues in daphnid body and inhibited the dissipation and transformation of phenanthrene in the medium, while 10-μm MPs did not show significant effects on the bioaccumulation, dissipation, and transformation of phenanthrene. The differences may be attributed to higher adsorption of phenanthrene on 50-nm NPs than 10-μm MPs. Our findings underlined the high potential ecological risks of FPs, and suggested that NPs should be given more concerns, in terms of their interaction with hydrophobic pollutants in the environment.
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•Nano-plastics (NPs) and phenanthrene had additive joint toxicity to D. magna.•NPs enhanced bioaccumulation of phenanthrene-derived residues in daphnid body.•NPs inhibited dissipation and transformation of phenanthrene in the medium.•Microplastics (MPs) did not show significant effects.
Compared to microplastics, nanoplastics had additive toxic effects with phenanthrene, increased bioaccumulation in D. magna, and inhibited its dissipation in the environment.
Nanoparticles (NPs) are defined as having at least one external dimension between 1 and 100 nm. Due to their small size, NPs have a large surface area to volume ratio giving them unique ...characteristics that differ from bulk material of the same chemical composition. As a result these novel materials have found numerous applications in medical and industrial fields with the result that environmental exposure to NPs is increasingly likely. Similarly, increased reliance on plastic, which degrades extremely slowly in the environment, is resulting in increased accumulation of micro-/nano-plastics in fresh and marine waters, whose ecotoxicological impacts are as yet poorly understood. Although NPs are well known to adsorb macromolecules from their environment, forming a biomolecule corona which changes the NP identity and how it interacts with organisms, significantly less research has been performed on the ecological corona (eco-corona). Secretion of biomolecules is a well established predator–prey response in aquatic food chains, raising the question of whether NPs interact with secreted proteins, and the impact of such interaction on NP uptake and ecotoxicity. We report here initial studies, including optimisation of protocols using carboxylic-acid and amino modified spherical polystyrene NPs, to assess interaction of NPs with biomolecules secreted by Daphnia magna and the impact of these interactions on NP uptake, retention and toxicity towards Daphnia magna.
Daphnia magna are an important environmental indicator species who may be especially sensitive to nanoparticles (NPs) as a result of being filter-feeders. This paper demonstrates for the first time that proteins released by Daphnia magna create an eco-corona around polystyrene NPs which causes heightened uptake of the NPs and consequently increases toxicity. The secreted protein eco-corona also causes the NPs to be less efficiently removed from the gut of D. magna and NPs remaining in the gut of D. magna affected the rate of subsequent feeding. Thus, fate of NPs in the environment should be evaluated and monitored under more realistic exposure scenarios.
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•Conditioning media by exposing to D. magna neonates resulted in significant release of proteins•Secreted proteins coated COOH- or NH2-PS NPs forming an eco-corona•Eco-corona-coated NPs had lower EC50 than uncoated NPs; NH2-PS NPs were more toxic than COOH-PS NPs with/without eco-corona•Higher retention of corona-coated NPs in D. magna gut post-exposure, affecting feeding ability•OECD protocols need revision for NP toxicity: corona formation, NP retention and feeding effects should be considered.
The effects of emerging environmental contaminants on human and environmental health is of high concern, especially those potentially induced by mixtures. The main goal of the present study was to ...assess the chronic effects of mixtures of citrate stabilized ≈5 nm gold nanoparticles (AuNP) and 1–5μm microplastics (MP) on Daphnia magna. A 21-day bioassay was carried out. The effect criteria were parental mortality, somatic growth and several reproductive parameters. AuNP induced parental mortality, reduced the total offspring and caused immobile juveniles and aborted eggs. MP induced parental mortality, delayed the first brood release, decreased the number of broods released, the total offspring, and caused immobile juveniles. All the mixtures caused higher toxicity than AuNP and MP alone. Based on parental mortality, evidences of antagonism between AuNP and MP were observed at low concentrations of both mixture components, whereas evidences of synergism at high concentrations were found. Chronic (21-day) exposure of D. magna to AuNPs, MP, and their mixtures can impair development, reproduction, ultimately leading to death.
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•21-day D. magna exposure to 5nm AuNP caused mortality and reproduction impairment.•21-day D. magna exposure to 1–5μm MP caused mortality and reproduction impairment.•Mixtures of AuNP and MP caused higher effects than the components individually.•Based on mortality, synergism at high concentrations of mixture components was found.•Based on mortality, antagonism at low concentrations of mixture components was found.
Neonicotinoids, broad-spectrum systemic insecticides, are the fastest growing class of insecticides worldwide and are now registered for use on hundreds of field crops in over 120 different ...countries. The environmental profile of this class of pesticides indicate that they are persistent, have high leaching and runoff potential, and are highly toxic to a wide range of invertebrates. Therefore, neonicotinoids represent a significant risk to surface waters and the diverse aquatic and terrestrial fauna that these ecosystems support. This review synthesizes the current state of knowledge on the reported concentrations of neonicotinoids in surface waters from 29 studies in 9 countries world-wide in tandem with published data on their acute and chronic toxicity to 49 species of aquatic insects and crustaceans spanning 12 invertebrate orders. Strong evidence exists that water-borne neonicotinoid exposures are frequent, long-term and at levels (geometric means=0.13μg/L (averages) and 0.63μg/L (maxima)) which commonly exceed several existing water quality guidelines. Imidacloprid is by far the most widely studied neonicotinoid (66% of the 214 toxicity tests reviewed) with differences in sensitivity among aquatic invertebrate species ranging several orders of magnitude; other neonicotinoids display analogous modes of action and similar toxicities, although comparative data are limited. Of the species evaluated, insects belonging to the orders Ephemeroptera, Trichoptera and Diptera appear to be the most sensitive, while those of Crustacea (although not universally so) are less sensitive. In particular, the standard test species Daphnia magna appears to be very tolerant, with 24–96hour LC50 values exceeding 100,000μg/L (geometric mean>44,000μg/L), which is at least 2–3 orders of magnitude higher than the geometric mean of all other invertebrate species tested. Overall, neonicotinoids can exert adverse effects on survival, growth, emergence, mobility, and behavior of many sensitive aquatic invertebrate taxa at concentrations at or below 1μg/L under acute exposure and 0.1μg/L for chronic exposure. Using probabilistic approaches (species sensitivity distributions), we recommend here that ecological thresholds for neonicotinoid water concentrations need to be below 0.2μg/L (short-term acute) or 0.035μg/L (long-term chronic) to avoid lasting effects on aquatic invertebrate communities. The application of safety factors may still be warranted considering potential issues of slow recovery, additive or synergistic effects and multiple stressors that can occur in the field. Our analysis revealed that 81% (22/27) and 74% (14/19) of global surface water studies reporting maximum and average individual neonicotinoid concentrations respectively, exceeded these thresholds of 0.2 and 0.035μg/L. Therefore, it appears that environmentally relevant concentrations of neonicotinoids in surface waters worldwide are well within the range where both short- and long-term impacts on aquatic invertebrate species are possible over broad spatial scales.
•Neonicotinoids in surface waters often exceed existing regulatory guidelines.•Environmental persistence indicates regulatory thresholds using acute toxicity tests may underestimate toxic potential.•Daphnia magna, industry standard, is at least1000 times less sensitive than mean of all other aquatic invertebrates.•Large differences in LEC50 values relate to sensitivity among species not potency among neonicotinoids.•Predict effects on communities at water concentrations ≥0.2 (max) or 0.035μg/L (avg)
•Exposure to MPs, Cr, and their combination caused significant deleterious effects and acute toxicity in D. magna.•Alterations in oxidative stress occurred in the groups treated with MPs and Cr alone ...and together.•Upon co-exposure to MPs, the Cr concentration, measured by ICP-OES, decreased, suggesting that MPs and Cr interact with each other.•A decrease in MP egestion via inhibition of P-gp activity in the MP-exposed groups, and MRP activity increased in some of the MP-exposed animals depending on Cr concentration.•MP exposure seemed to lead to the mitochondrial transcription dysfunction induced by Cr via sestrin-related mitochondrial biogenesis.
In this study, we investigated the individual and combined effects of microplastics (MPs) and chromium (Cr) on the freshwater water flea Daphnia magna by measuring mortality, bioaccumulation, antioxidative response, multixenobiotic resistance activity, and sestrin-related mitochondrial biogenesis in short-term assays and in vivo endpoints including reproduction and adult survival rate in long-term assays. Exposure to MPs, Cr, and their combination caused significant deleterious effects and acute toxicity in D. magna. Alterations in oxidative stress occurred in the groups treated with MPs and Cr alone and together. However, upon co-exposure to MPs, the Cr concentration, measured by inductively coupled plasma optical emission spectroscopy, decreased, suggesting that MPs and Cr interact with each other. Based on enzymatic activities, we noted a decrease in MP egestion via inhibition of P-glycoprotein activity in the MP-exposed groups, and multidrug resistance–associated protein activity increased in some of the MP-exposed animals depending on Cr concentration. On the other hand, MP exposure seemed to lead to mitochondrial transcription dysfunction induced by Cr via sestrin-related mitochondrial biogenesis. Overall, these results indicate that co-exposure to MPs and Cr causes acute toxicity in D. magna but lacks the chronic toxicity (21 days) and mitochondrial dysfunction caused by Cr exposure alone.
In the present study, an ecotoxicological approach to the evaluation of the insecticide Pyriproxifen in the crustacean Daphnia magna was done. Acute toxicity tests (48 h), feeding behavior test (5 h) ...and chronic toxicity test (21 days) were carried out on a parental daphnid generation (F0). Pyriproxifen D. magna EC50 value in our experimental conditions was 336.47 μg/L. Based on this result, sublethal test concentrations were selected for the feeding study and the F0 chronic experiment. Filtration and ingestion rates of D. magna exposed animals did not show any significant difference respect to control daphnids. However, daphnids from the parental F0 generation when exposed to the insecticide during 21 days showed a decreased in all the reproductive parameters tested (mean total neonates per female, mean brood size, time to first brood, and mean number of broods per female) as well as in the population statistic growth rate (r), although survival was not affected. On the other hand, offspring from F0 females exposed to the highest Pyriproxifen concentration (14.02 μg/L) were separated in two F1 generation experiments. One group was transferred during 21 days to a medium free of toxicant (F1 generation-TC group) while the other group was exposed during 21 days to the same insecticide concentration as their mothers (14.02 μg/L) (F1 generation-TT group). Results from both experiments determined a decreased in most of the reproductive parameters which was higher in the F1-TT group, although some of them were recovered in the F1-TC group. On the other hand, the morphological analysis of the daphnids showed that the coloration pattern was altered in the daphnids exposed to the insecticide, together with a significant size decreased, and neonates from F0 progeny with the same morphological abnormality. Finally, we determined that the insecticide caused the appearance of males among the offspring generated by the F0.
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•Pyriproxyfen sublethal concentrations induced changes in reproductive parameters.•Pyriproxifen D. magna multigeneration study•Population recovery process after exposure of mothers to insecticide•Pyriproxifen induced morphological abnormality and appearance of males in daphnid population.
The serotonin signaling system plays a crucial role in regulating the ontogeny of crustaceans. Here, we describe the effects of different concentrations of the 5-hydroxytryptamine 1A receptor ...antagonist (WAY-100635) on the induced antipredation (
as the predator), morphological, behavioral, and life-history defenses of
and use transcriptomics to analyze the underlying molecular mechanisms. Our results indicate that exposure to WAY-100635 leads to changes in the expression of different defensive traits in
when faced with fish predation risks. Specifically, as the length of exposure to WAY-100635 increases, high concentrations of WAY-100635 inhibit defensive responses associated with morphological and reproductive activities but promote the immediate negative phototactic behavioral defense of
. This change is related to the underlying mechanism through which WAY-100635 interferes with gene expression of G-protein-coupled GABA receptors by affecting GABBR1 but promotes serotonin receptor signaling and ecdysteroid signaling pathways. In addition, we also find for the first time that fish kairomone can significantly activate the HIF-1α signaling pathway, which may lead to an increase in the rate of immediate movement. These results can help assess the potential impacts of serotonin-disrupting psychotropic drugs on zooplankton in aquatic ecosystems.
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