Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.940
Filtrar
1.
Environ Pollut ; 266(Pt 3): 115142, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32750525

RESUMO

Chemical warfare agents (CWA) dumped worldwide in all types of aquatic reservoirs pose a potential environmental hazard. Leakage of CWAs from eroding containers at dumping sites had been observed, and their presence in the tissues of aquatic animals was confirmed. However, the ecological effects of CWA have not yet been studied. In standardized laboratory bioassays, we tested if sublethal concentration of Clark I, an arsenic based CWA, can affect life histories (somatic growth rate, fecundity, size at maturity), population growth rate and stable isotope signatures of a keystone crustacean grazer Daphnia magna. We found that the life histories and fitness of daphnids reared in the presence of Clark I differed from those reared in Clark-free conditions. The effects were observed when Clark I concentrations were no less than 5 µg×L-1. With increasing concentrations of the tested CWA, all of the tested parameters decreased linearly. The finding indicates that even sublethal concentrations of Clark I can affect crustacean populations, which should be taken into account when assessing the environmental risks of this particular CWA. We found intraspecific diversity in susceptibility to Clark I, with some clones being significantly less vulnerable than others. We also found that in the presence of Clark I, the ratio of heavy and light isotopes of nitrogen in the bodies of daphnids was affected - daphnids exhibited δ15N enrichment with increasing concentrations of this CWA. The isotopic composition of carbon was not affected by the presence of Clark I. The nitrogen isotopic signature may be used as an indicator of stress in zooplankton exposed to the presence of toxic xenobiotics.


Assuntos
Arsênico , Substâncias para a Guerra Química , Poluentes Químicos da Água/análise , Animais , Daphnia , Isótopos de Nitrogênio/análise
2.
Environ Pollut ; 266(Pt 2): 115349, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32791466

RESUMO

Dissolved organic matter (DOM) is an essential factor in natural waters to affect the bioavailability of hydrophobic organic compounds (HOCs). Climate warming may influence the partition of HOCs between DOM and water as well as the physiology of organisms. Thus, we hypothesized that elevated temperature might affect the bioavailability of HOCs in the presence of DOM. To test this hypothesis, the effect of temperature on the bioavailability of pyrene to Daphnia magna (D. magna) in water-DOM (fulvic acid) system was investigated. The results showed that, although the concentration of freely dissolved pyrene increased slightly with temperature in the presence of DOM when the level of total dissolved pyrene was kept constant, D. magna immobilization (increased by 50.0-167%) and internal body burden of pyrene (increased by 18.4-41.5%) increased significantly with every 4 °C increase in temperature (16, 20, 24 °C). The main reasonable explanation for this result is that elevated temperature promoted pyrene uptake by D. magna. It was found that the increase percentage of 1-hydroxypyrene (main metabolite of pyrene) concentrations with temperature was higher than that of pyrene concentrations in the body except gut of D. magna. This result indicated that increased temperature might enhance the metabolic rates of D. magna, thus leading to increased uptake rate of freely dissolved and DOM-associated pyrene. This study suggests that elevated temperature might enhance the bioavailability of HOCs in natural waters through influencing both the bioavailable fraction of HOCs and their uptake rates in aquatic organisms, and this should be considered for evaluating their eco-environmental risks under the context of climate warming.


Assuntos
Daphnia , Poluentes Químicos da Água/análise , Animais , Disponibilidade Biológica , Pirenos/análise , Temperatura
3.
Aquat Toxicol ; 226: 105584, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32795838

RESUMO

There is increasing evidence about negative effects of fungicides on non-target organisms, including parasitic species, which are key elements in food webs. Previous experiments showed that environmentally relevant concentrations of fungicide tebuconazole are toxic to the microparasite Metschnikowia bicuspidata, a yeast species that infects the planktonic crustacean Daphnia spp. However, due to their short-term nature, this and other experimental studies were not able to test if parasites could potentially adapt to these contaminants. Here, we tested if M. bicuspidata parasite can adapt to tebuconazole selective pressure. Infected D. magna lineages were reared under control conditions (no tebuconazole) and environmentally realistic tebuconazole concentrations, for four generations, and their performance was compared in a follow-up reciprocal assay. Additionally, we assessed whether the observed effects were transient (phenotypic) or permanent (genetic), by reassessing parasite fitness after the removal of selective pressure. Parasite fitness was negatively affected throughout the multigenerational exposure to the fungicide: prevalence of infection and spore load decreased, whereas host longevity increased, in comparison to control (naive) parasite lineages. In a follow-up reciprocal assay, tebuconazole-conditioned (TEB) lineages performed worse than naive parasite lineages, both in treatments without and with tebuconazole, confirming the cumulative negative effect of tebuconazole. The underperformance of TEB lineages was rapidly reversed after removing the influence of the selective pressure (tebuconazole), demonstrating that the costs of prolonged exposure to tebuconazole were phenotypic and transient. The microparasitic yeast M. bicuspidata did not reveal potential for rapid evolution to an anthropogenic selective pressure; instead, the long-term exposure to tebuconazole was hazardous to this non-target species. These findings highlight the potential environmental risks of azole fungicides on non-target parasitic fungi. The underperformance of these microbes and their inability to adapt to such stressors can interfere with the key processes where they intervene. Further research is needed to rank fungicides based on the hazard to non-target fungi (parasites, but also symbionts and decomposers), towards more effective management and protective legislation.


Assuntos
Daphnia/efeitos dos fármacos , Fungicidas Industriais/toxicidade , Metschnikowia/efeitos dos fármacos , Modelos Biológicos , Triazóis/toxicidade , Poluentes Químicos da Água/toxicidade , Adaptação Fisiológica/efeitos dos fármacos , Animais , Daphnia/microbiologia , Interações entre Hospedeiro e Microrganismos/efeitos dos fármacos , Metschnikowia/crescimento & desenvolvimento
4.
Ecotoxicol Environ Saf ; 202: 110959, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800231

RESUMO

Long-term field experiments were performed to evaluate the phytotoxic properties of fungal metabolites in oil-contaminated soil and to assess the impact of contamination on the allelopathic activity of soil mycobiota. Two contrasting soils of Northwest Russia (sandy and loamy podzols) exposed to oil contamination underwent changes in abundance and allelopathic activities of soil fungi. Shifts within the microbial community caused by oil contamination affected not only oil-decomposition rates but also ecotoxicity of contaminated soil. There were significant differences in soil toxicity dynamics between sandy and loamy podzols. Four years after contamination, ecotoxicity of loamy podzol decreased, whereas sandy podzol remained highly toxic even nine years after contamination. The abundance and allelopathic activity of fungi is correlated with hydrocarbon degradation dynamics. The soil fungal community demonstrated high allelopathic activity which decreased over time in fertile loamy podzolic soil, whereas in poor sandy podzolic soil it remained high over the nine-year monitoring period. The results illustrate how oil contamination may influence allelopathic interactions in soil and demonstrate the advantage of using fungal metabolite toxicity test for testing of oil-contaminated soil samples.


Assuntos
Fungos/efeitos dos fármacos , Hidrocarbonetos/toxicidade , Micotoxinas/toxicidade , Petróleo/toxicidade , Microbiologia do Solo , Poluentes do Solo/análise , Animais , Biodegradação Ambiental , Daphnia/efeitos dos fármacos , Daphnia/crescimento & desenvolvimento , Ecotoxicologia , Fungos/metabolismo , Hidrocarbonetos/análise , Micotoxinas/metabolismo , Petróleo/análise , Federação Russa , Solo/química , Testes de Toxicidade , Triticum/efeitos dos fármacos , Triticum/crescimento & desenvolvimento
5.
Environ Pollut ; 265(Pt B): 114993, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806449

RESUMO

Among the most used non-steroidal anti-inflammatory drugs (NSAIDs), ketoprofen (KTF) assumes an important position. Nevertheless, its ecotoxicological effects in non-target organisms are poorly characterized, despite its use and frequency of occurrence in aquatic matrices. Thus, the aim of this study was to evaluate the possible toxicological effects of KTF contamination, in two freshwater species, Lemna minor and Daphnia magna, by measuring biochemical, physiological and population parameters. To attain this objective, both species were exposed to KTF at the same concentrations (0, 0.24, 1.2, 6 and 30 µg/L). L. minor plants were exposed during 4 d to these levels of KTF, and the enzymatic activity (catalase (CAT), glutathione S-transferases (GSTs) and carbonic anhydrase (CA)), and pigments content (chlorophylls a, b and total and carotenoids) were analyzed to evaluate the toxicity of this drug. D. magna was acutely and chronically exposed to KTF, and enzymatic activities (CAT, GSTs and cyclooxygenase (COX)), the feeding rates, and reproduction traits were assessed. In L.minor, KTF provoked alterations in all enzyme activities, however, it was not capable of causing any alteration in any pigment levels. On the other hand, KTF also provoked alterations in all enzymatic activities in D. magna, but did not affect feeding rates and life-history parameters. In conclusion, exposure to KTF, provoked biochemical alterations in both species. However, these alterations were not reflected into deleterious effects on physiological and populational traits of L. minor and D. magna.


Assuntos
Araceae , Cetoprofeno , Poluentes Químicos da Água , Animais , Daphnia , Água Doce
6.
Proc Biol Sci ; 287(1930): 20201069, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32605517

RESUMO

Expression of adaptive reaction norms of life-history traits to spatio-temporal variation in food availability is crucial for individual fitness. Yet little is known about the neural signalling mechanisms underlying these reaction norms. Previous studies suggest a role for the dopamine system in regulating behavioural and morphological responses to food across a wide range of taxa. We tested whether this neural signalling system also regulates life-history reaction norms by exposing the zooplankton Daphnia magna to both dopamine and the dopamine reuptake inhibitor bupropion, an antidepressant that enters aquatic environments via various pathways. We recorded a range of life-history traits across two food levels. Both treatments induced changes to the life-history reaction norm slopes. These were due to the effects of the treatments being more pronounced at restricted food ration, where controls had lower somatic growth rates, higher age and larger size at maturation. This translated into a higher population growth rate (r) of dopamine and bupropion treatments when food was restricted. Our findings show that the dopamine system is an important regulatory mechanism underlying life-history trait responses to food abundance and that bupropion can strongly influence the life history of aquatic species such as D. magna. We discuss why D. magna do not evolve towards higher endogenous dopamine levels despite the apparent fitness benefits.


Assuntos
Daphnia/fisiologia , Dopamina/metabolismo , Animais , Evolução Biológica , Alimentos , Traços de História de Vida , Reprodução , Zooplâncton
7.
Environ Sci Pollut Res Int ; 27(28): 35650-35660, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32601865

RESUMO

Pathways of photochemical degradation of a cardiovascular drug verapamil under conditions relevant to natural waters and the toxicity of the photoproducts to Daphnia magna were investigated. Photodegradation was shown to proceed via photocatalysed mechanism. Two main photodegradation pathways were recognised: the first leading to hydroxylation at the methylamino position followed by splitting of verapamil molecule into two fragments, and the second providing the main active metabolite of verapamil, norverapamil, and a series of norverapamil isomers, followed again by their splitting at the amino group position. Twenty-two products of photodegradation were identified. Toxicity assays in sublethal concentrations of the parental drug, of the photoproduct mixture, and of norverapamil revealed no direct negative response in Daphnia magna to verapamil. On the other hand, photochemical products significantly lowered the number of juveniles, number of clutches, and body size of Daphnia. The exposition of Daphnia to norverapamil showed the same but even more pronounced effects than its exposition to the mixture of photoproducts, which leads to the conclusion that norverapamil is mainly responsible for the toxicity of photoproduct mixture and represents a noteworthy threat to aquatic invertebrates.


Assuntos
Daphnia , Poluentes Químicos da Água , Animais , Fotólise , Verapamil
8.
Chemosphere ; 259: 127473, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32622247

RESUMO

Cationic polymers (CPs) are widely used chemicals for wastewater treatment applications and in various "down-the-drain" household products. The aquatic toxicity of CPs results from an electrostatic interaction with negatively charged cell surfaces. These effects are greatly mitigated by the binding affinity of CPs to total organic carbon (TOC) in surface water. Consequently, baseline aquatic toxicity tests of CPs using clean lab water (TOC < 2 mg/L) typically overestimate toxicity and risk which is greatly mitigated at higher environmentally relevant OC levels. However, the point at which mitigation begins is not well defined and low-level TOC in lab water may influence the baseline toxicity outcome. Similarly, divalent cations, quantified as water hardness, may modulate the electrostatic binding between OC and CP. Although standard guidelines define limits for lab water hardness and TOC, the consequences of variability within those limits on test outcome is unknown. We investigated the impact of part-per-billion (ppb) additions of TOC to lab water at different hardness levels on CP acute toxicity to Daphnia magna and Raphidocelis subcapitata. In both species, the acute toxicities of CPs with different molecular weight and charge density varied by > 10-fold in response to slight changes in TOC and water hardness, although parameters were maintained within guideline limits. When determining the baseline aquatic toxicity of CPs, the lab water should be standardized at the lowest biologically tolerable hardness and TOC at a reliably measurable level (>1 - < 2 mg/L) to reduce variability and increase the reliability of the toxicity estimate.


Assuntos
Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Animais , Cátions , Daphnia/efeitos dos fármacos , Monitoramento Ambiental/normas , Água Doce/química , Dureza , Polímeros/toxicidade , Reprodutibilidade dos Testes , Testes de Toxicidade
9.
Huan Jing Ke Xue ; 41(5): 2239-2246, 2020 May 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608841

RESUMO

The occurrence and risk assessment of eight typical pharmaceutical active compounds (PhACs) in a receiving water body of wastewater treatment plant effluent were investigated. The results showed that the total concentrations of eight PhACs in summer and winter ranged from 27.6 to 226.4 ng·L-1 and 56.6 to 368.8 ng·L-1, respectively. The concentration of caffeine (16.2-125.8 ng·L-1) was highest, followed by roxithromycin (3.3-89.2 ng·L-1) and ibuprofen (3.6-59.2 ng·L-1). The total ecological risks (mixture risk quotients, MRQ) of eight PhACs to green algae, daphnia, and fish were 1.51, 0.08, and 5.68 in summer and 8.34, 0.22, and 6.45 in winter, respectively. The contribution rates of ketoconazole, erythromycin, and ibuprofen exceeded 49%, 85%, and 92% for MRQ in green algae, daphnia, and fish, respectively. In terms of sensitive species, green algae and fish are the most sensitive to PhACs in winter and summer, respectively. The results of 21 d chronic toxicity showed that mixed PhACs effect normal development and reproduction of Daphnia magna, resulting in an increase in reproductive capacity and swimming activity, and a reduction in heart rate and thoracic limb activity.


Assuntos
Daphnia , Poluentes Químicos da Água/análise , Animais , Peixes , Águas Residuárias , Água
10.
Aquat Toxicol ; 226: 105556, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32652413

RESUMO

Ribosomal (r)DNA is a highly dynamic, conserved, multigene family whose sequence homogeneity is thought to be maintained by intra- and interchromosomal recombination, which are capable of changing rDNA copy number. It is generally not known how environmental stress such as sublethal exposure to environmentally relevant concentrations of metals impacts rDNA copy number. To determine how chronic metal exposure affects rDNA, we measured copy number of the 18S rRNA gene in 355 copper and nickel-exposed samples and 132 metal-free samples derived from 325 mutation accumulation (MA) lines of two genetically distinct Daphnia pulex lineages. The MA lines were sampled at four time points over 100+ generations of clonal propagation. The copy number of rDNA was also measured in 15 individuals sampled from a metal-free non-MA control population established from the same progenitor as one of the MA lineages. We found that mean rDNA copy number fluctuated across lines exposed to metals with a tendency to decrease over time. In contrast, mean rDNA copy number in the metal-free control lines and the non-MA population remained stable over time. It is generally accepted that extreme rDNA loss results in the loss of organism fitness. Thus, fluctuations in rDNA copy number, including losses, could affect the long-term viability of natural populations of Daphnia in metal-contaminated habitats.


Assuntos
Variações do Número de Cópias de DNA/efeitos dos fármacos , DNA Ribossômico/genética , Daphnia/efeitos dos fármacos , Metais Pesados/toxicidade , Acúmulo de Mutações , Poluentes Químicos da Água/toxicidade , Animais , Cobre/toxicidade , Daphnia/genética , Níquel/toxicidade , RNA Ribossômico 18S/genética , Reprodução/efeitos dos fármacos , Reprodução/genética
11.
Sci Total Environ ; 742: 140611, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32721740

RESUMO

Strobilurin fungicides (SFs), a class of new fungicides, use strobilurin A as a lead compound. However, with excessive production and usage, the SF residues in soil and aquatic ecosystems may lead to environmental pollution. The mechanism of action (MOA) of SFs is respiratory inhibition of fungal mitochondria. Specifically, azoxystrobin (AZO), pyraclostrobin (PYR), trifloxystrobin (TRI), fluoxastrobin (FLUO), picoxystrobin (PICO), and kresoxim-methyl (KRE) are considered the most widely used SFs. The toxicities of those six fungicides in the environment are still unclear. The present review summarized the toxicities of the six SFs to terrestrial and aquatic biota, including mice, amphibians, aquatic organisms (fish, daphnia, algae, etc.), apoidea, soil animals (earthworms and Folsomia fimetaria), and soil microorganisms. We also review the residue, fate, and transportation of SFs. The results indicate that SFs are highly toxic to aquatic and soil organisms and pose potential risks to ecosystems. Current toxicology studies are more focused on acute or chronic toxicity, but the underlying mechanisms are still unclear and require further analysis. In addition, a simple and scientific analysis method is needed to compare the toxicity differences of different SFs to the same test organisms or differences in the same SFs to different test organisms.


Assuntos
Fungicidas Industriais , Animais , Daphnia , Ecossistema , Ecotoxicologia , Camundongos , Estrobilurinas
12.
Ecotoxicology ; 29(7): 892-899, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32728873

RESUMO

Daphnia has been widely used as an indicator species in aquatic biomonitoring for decades. Traditional toxicity assays based on lethality take a long time to assess, and the effect mode of contaminants is not clear. Because of the translucency of the Daphnia body and the application of fluorescent probes in cell staining, different intoxicated parts can be visualized. In this study, a double-staining method using two fluorescent dyes, Calcein AM (cell-permeant dye) and Propidium Iodide (cell-impermeant dye), was carried out on Daphnia magna exposed to six pathogens: Salmonella spp. (four strains) and Shigella spp. (two strains). The results showed that those bacteria caused different infections on daphnia depending on the age of this organism and bacterial concentrations. In detail, S. dublin and S. sonnei are the most harmful to Daphnia when they cause damage at smaller concentrations at the younger stage (3 weeks old). Interestingly, older Daphnia can give responses to nearly 10 CFU/ml to less than 100 CFU/ml of some bacteria strains. In another experiment, S. sonnei disturbed Daphnia after just 10 min of exposure, and Daphnia adapted to S. choleraesuis, S. typhi, and S. flexneri at the early stage (3 weeks old) after 1 h of exposure. Moreover, the damaged areas of the daphnia body were directly observed via a microscope, contributing to the understanding and the prediction of toxicity mechanisms.


Assuntos
Daphnia/microbiologia , Salmonella/química , Shigella/química , Testes de Toxicidade/métodos , Animais , Corantes Fluorescentes/análise , Coloração e Rotulagem
13.
Environ Pollut ; 266(Pt 3): 115092, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32650302

RESUMO

Antidepressants discharged into natural waters are likely to become a new type of endocrine pollutant, which may impact the interspecific relationship in aquatic ecosystem. Induced defense of cladocerans plays an important role in maintaining the balance of interspecific relationships between cladocerans and higher trophic levels. Here we studied the effects of antidepressant sertraline, a selective serotonin reuptake inhibitor, on the induced defensive traits of Ceriodaphnia cornuta in response to invertebrate predator Chaoborus larvae kairomone, including morphological defense and life history traits. We also conducted the predation experiments to check the selection rate of Chaoborus larvae during directly ingesting C. cornuta that were exposed to Chaoborus larvae kairomone at high concentration of sertraline. Results showed sertraline had an interference effect on the induced morphological defense of C. cornuta in response to Chaoborus larvae kairomone, i.e. the high concentration of sertraline (20 and 100 µg L-1) significantly reduced the horns induction. However, the different concentrations of sertraline generally did not affect the life history traits of C. cornuta, regardless of presence or absence of Chaoborus larvae kairomone. The predation experiment demonstrated that the inhibition of sertraline on the induced morphological defense of C. cornuta can promote the feeding selective efficiency of Chaoborus larvae, and thus cause C. cornuta easily to be predated by Chaoborus larvae. Our results suggested that sertraline at the concentrations that are not direct harmful to life history traits of C. cornuta can seriously affect the predator-prey relationship, indicating that effects of pollutants on interspecific relationships should be considered comprehensively to avoid underestimating the potential risk of pollutants to ecosystems.


Assuntos
Ecossistema , Sertralina , Animais , Antidepressivos , Daphnia , Larva , Feromônios
14.
PLoS Negl Trop Dis ; 14(7): e0008479, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32687496

RESUMO

The existing mosquito pesticide repertoire faces great challenges to sustainability, and new classes of pesticides are vitally needed to address established and emerging mosquito-borne infectious diseases. RNA interference- (RNAi-) based pesticides are emerging as a promising new biorational mosquito control strategy. In this investigation, we describe characterization of an interfering RNA pesticide (IRP) corresponding to the mosquito Shaker (Sh) gene, which encodes an evolutionarily conserved voltage-gated potassium channel subunit. Delivery of the IRP to Aedes aegypti adult mosquitoes in the form of siRNA that was injected or provided as an attractive toxic sugar bait (ATSB) led to Sh gene silencing that resulted in severe neural and behavioral defects and high levels of adult mortality. Likewise, when provided to A. aegypti larvae in the form of short hairpin RNA (shRNA) expressed in Saccharomyces cerevisiae (baker's yeast) that had been formulated into a dried inactivated yeast tablet, the yeast IRP induced neural defects and larval death. Although the Sh IRP lacks a known target site in humans or other non-target organisms, conservation of the target site in the Sh genes of multiple mosquito species suggested that it may function as a biorational broad-range mosquito insecticide. In support of this, the Sh IRP induced both adult and larval mortality in treated Aedes albopictus, Anopheles gambiae, and Culex quinquefasciatus mosquitoes, but was not toxic to non-target arthropods. These studies indicated that IRPs targeting Sh could one day be used in integrated biorational mosquito control programs for the prevention of multiple mosquito-borne illnesses. The results of this investigation also suggest that the species-specificity of ATSB technology, a new paradigm for vector control, could be enhanced through the use of RNAi-based pesticides.


Assuntos
Agentes de Controle Biológico/farmacologia , Culicidae/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Oligonucleotídeos/farmacologia , Superfamília Shaker de Canais de Potássio/metabolismo , Animais , DNA , Daphnia , Feminino , Inativação Gênica , Larva/efeitos dos fármacos , RNA Interferente Pequeno , Superfamília Shaker de Canais de Potássio/genética
15.
Sci Total Environ ; 740: 140045, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32559538

RESUMO

This study addresses short-term habituation of the escape response in the aquatic crustacean Daphnia magna evoked by sudden changes in light intensity, using a high-throughput system. Daphnia magna exhibits a marked phototactic behaviour and swim away from light to avoid predation by fish. Currently, there is no information available on the habituation of this phototactic response. The Daphnia photomotor response assay (DPRA) measures the distance moved after a sudden increase in light intensity. Using DPRA, it is possible to determine not only the magnitude of the phototactic response, but also its habituation after repetitive cycles of light and darkness. The progressive reduction observed in response to a series of light stimuli in the proposed assay meet the criteria for habituation. Most cholinergic and serotonergic modulators enhanced photomotor responses and reduced habituation. Dopaminergic and histaminergic modulators also reduced habituation, whereas diazepam was the only compound that increased habituation. Imidacloprid, apomorphine, diphenhydramine, diazepam, and memantine decreased photomotor responses. Thus, the DPRA was also predictive in assessing the effects of neuroactive and neurotoxic environmental contaminants such as selective serotonin reuptake inhibitors, diazepam, organophosphorous, and neonicotinoid pesticides. We conclude that the proposed DPRA may be an effective screening tool for compounds that can impair predation avoidance behaviour in aquatic organisms.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Animais , Daphnia , Peixes , Fototaxia
16.
Environ Sci Pollut Res Int ; 27(28): 35000-35007, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32583109

RESUMO

Fluazinam (FZN) is a dinitroaniline fungicide. To evaluate the environmental risk of FZN in aquatic environments and ascertain the potential danger to typical aquatic organisms in China, the acute toxicity of FZN to representative aquatic organisms, including Brachydanio rerio, Chlorella vulgaris Beij., Daphnia magna Straus, and Xenopus laevis, was measured, and its bioaccumulation properties in Brachydanio rerio were further investigated. The results showed that the acute toxicity of FZN to Brachydanio rerio and Xenopus laevis is extremely high, and the bioaccumulation factor BCF8d of FZN in Brachydanio rerio ranges between 2287 and 3570, implying that it has high bioaccumulation properties. FZN poses a strong environmental risk for aquatic organisms and possesses great bioaccumulation properties, which may cause pollution to aquatic environments.


Assuntos
Chlorella vulgaris , Poluentes Químicos da Água , Aminopiridinas , Animais , Organismos Aquáticos , Bioacumulação , China , Daphnia , Peixe-Zebra
17.
Environ Sci Pollut Res Int ; 27(28): 35459-35473, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32592062

RESUMO

Raphidiopsis raciborskii is being considered an expanding, invasive species all over the world. It is a potentially toxin producer cyanobacterium and form blooms specially in (sub)tropical lakes, causing concern to public health. Thus, controlling such phenomena are of vital importance. To test the hypothesis that a tropical clone of Daphnia laevis is able to reduce the biomass of R. raciborskii, we performed a mesocosm experiment simulating a bloom of this cyanobacterium in field conditions and exposing it to ecologically relevant densities of daphniids. In addition, we tested the hypothesis that omnivorous fish would be able to exert a top-down effect on Daphnia, decreasing the effectiveness of this control. We used treatments with (10 and 20 Daphnia L-1) or without Daphnia and fish (3 per mesocosm). Daphnia was able to significantly reduce the biomass of R. raciborskii only at the highest density tested. Fish had low effect on Daphnia biomass, but it is suggested that nutrient recycling by fish might have contributed to the higher R. raciborskii biomass in fish treatments. This is the first evidence of Daphnia control over saxitoxin-producing cyanobacteria in a tropical ecosystem.


Assuntos
Cianobactérias , Cylindrospermopsis , Animais , Daphnia , Ecossistema , Lagos
18.
Environ Sci Pollut Res Int ; 27(25): 31489-31504, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32488719

RESUMO

Magnetic nanoparticles (MNPs) are used in a wide range of sectors ranging from electronics to biomedicine, as well as in eutrophicated lake restoration due to their high P, N, and heavy metal adsorption capacity. This study assessed the effects of MNPs on mortality and morphometric changes of D. magna. According to the SEM, the synthesised MNPs were found to have spherical nanoparticles, be uniformly distributed, and have a homolithic size distribution of 50-110 nm. The EDX spectra confirmed the elemental structure and purities of these MNPs. A total of 396 neonates were used for short-term bioassays (96 h) through the MNPs in the laboratory (16:8 photoperiod). Experiments were applied in triplicate for each concentration of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs and their respective control groups. Mortality and morphological measurements of each individual were recorded every 24 h. In the probit analysis, the 96-h LC50 (p < 0.05) for CuFe2O4, CoFe2O4, and NiFe2O4 MNPs was calculated to be 1.455 mg L-1, 39.834 mg L-1, and 21.730 mg L-1, respectively. CuFe2O4 MNPs were found to be more toxic than the other two MNPs. The concentrations of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs drastically affected life span and morphologic growth of D. magna as a result of a short time exposure. The results of this study are useful for assessing what risks they pose to freshwater ecosystems.


Assuntos
Nanopartículas de Magnetita , Nanopartículas Metálicas , Poluentes Químicos da Água , Animais , Daphnia , Ecossistema , Compostos Férricos , Humanos , Recém-Nascido
19.
Chemosphere ; 259: 127407, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593821

RESUMO

The objective of this study was to investigate the impact of two pharmaceuticals, diclofenac and sulfamethoxazole, and their binary mixture on aquatic organisms, marine bacteria Aliivibrio fischeri, crustacean Daphnia magna, and vascular plant Lemna minor. The binary mixture of the drugs showed the highest toxicity towards the model organisms. Diclofenac had an average toxicity which posed a high environmental risk to aquatic organisms, while sulfamethoxazole was characterized by a low toxicity with low environmental risk. The organism most sensitive to diclofenac was A. fischeri (IC50 = 8.72 ± 1.14 mg L-1) and for sulfamethoxazole and the binary mixture, it was L. minor (IC50 = 12.56 ± 4.48 and 4.83 ± 0.43 mg L-1, respectively). The toxicity of the mixture was predicted using the Concentration Addition and Independent Action models, and the results were compared with the experimental data. None of the models suitably predicted the real toxicity of the pharmaceutical mixture. Interactions between the mixture components were confirmed by calculating the mixture toxicity index values which showed that the pharmaceuticals displayed synergistic or partial additive effects which depended on the selected test organism and test duration. When added as a complex matrix to wastewater (at a concentration of 2 mg L-1 each), the pharmaceuticals did not display increased toxicity. This observation confirms that the presence of micro-contaminants in aquatic environments may cause interactions between different compounds, the results of which are difficult to predict and model.


Assuntos
Diclofenaco/toxicidade , Sulfametoxazol/toxicidade , Poluentes Químicos da Água/toxicidade , Aliivibrio fischeri/efeitos dos fármacos , Animais , Organismos Aquáticos , Araceae/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Águas Residuárias , Poluentes Químicos da Água/análise
20.
Sci Total Environ ; 728: 138795, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32570314

RESUMO

Because zooplankton is potentially limited by phosphorus (P) in freshwater, they may modify their body P distributions in different biochemical and anatomic components depending on the environmental P levels. In the present study, we quantified the distribution and regulation of P in a freshwater zooplankton Daphnia magna under P-limited conditions by using 33P as a radiotracer. We demonstrated that the P allocation patterns in D. magna were independent of the ontogenic development. Carapace accounted for 35-54% of total body P, followed by small molecules and nucleic acids (11-30%), whereas phospholipids represented only a minor P pool. The proportion of body P allocated into carapace decreased from 51.8% in +P adults to 16.5% in the -P adults, and a lower proportion of body P was also allocated to eggs in the -P adults than in the +P adults (3.8 vs. 16.5%). Meanwhile, no difference in allocation pattern was detected in the juveniles under +P and -P conditions, demonstrating an interaction between effects of P condition and ontogeny. Furthermore, the P turnover rates of nucleic acids and phospholipids in the -P juveniles were only half of those found in the +P individuals, suggesting a reduced metabolic rate under P-deficient conditions. However, the P turnover rate of small molecules, nucleic acids and phospholipids did not vary with the P condition in adults. It appeared that the adults could maintain their basic P metabolism by down-regulating the P allocation to carapace and eggs. Our results provide an insight into the tolerance of zooplankton to P-deficiency and bear implications on involvement of Daphnia in regulation of P cycling and availability in the epilimnion.


Assuntos
Fósforo , Zooplâncton , Animais , Daphnia , Cadeia Alimentar , Água Doce , Nutrientes
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA