RESUMO
An integral analysis of the acute and chronic toxicity, bioaccumulation, sites of entry, and distribution of four trace metals: copper, iron, lead, and nickel, and the non-trace metal mercury were performed in the ciliate Paramecium caudatum. Mercury was the fastest metal accumulated, and the most toxic. The sensitivity of Paramecium caudatum to the five metals tested (Cu, Fe, Hg, Ni, and Zn) falls in the range of other ciliate species. We observed similarities between the toxicity of the five metals to the ciliate P. caudatum with the rotifer Euchlanis dilatata: (a) Mercury was the most toxic metal in terms of acute and body burdens. (b) Acute values were very similar in both species, Hg as the most toxic and Fe as the less toxic, (c) the vacuole/ingestion chronic tests were more sensitive than growth inhibition chronic tests. These analyses would ideally help generate safer guidelines for protecting aquatic biota.
Assuntos
Mercúrio , Metais Pesados , Paramecium caudatum , Rotíferos , Oligoelementos , Poluentes Químicos da Água , Animais , Bioacumulação , Carga Corporal (Radioterapia) , Metais/análise , Mercúrio/análise , Oligoelementos/análise , Metais Pesados/análise , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/análise , Monitoramento AmbientalRESUMO
Effectiveness of pyrethroid insecticides against pests including bark beetles (Dendroctonus spp.) is well known, but little is known about their (a) residuality and persistence in forests after application to control an outbreak and (b) ability to bioaccumulate in insects, which could cause adverse effects on the trophic chains. The 24 h lethal toxicity, bioaccumulation factors, and lethal body burdens of the pyrethroid insecticides bifenthrin, deltamethrin, and cypermethrin were evaluated in the bark beetle Dendroctonus mexicanus. The residuality and persistence of the insecticide bifenthrin in the forest ecosystem (soil, water, and sediment) was also monitored after its application in a region infested by bark beetles. We determined whether contamination of soil, water, and sediments occurred near the sanitation site. For D. mexicanus, the most toxic insecticide for adults was bifenthrin for topical application (LC50 = 0.94 mg/L) and cypermethrin for bark application (LC50 = 5.04 mg/L). The insecticide that bioaccumulated the most in the insect body was deltamethrin (622.41 µg g-1 dw) and the insecticide that bioaccumulated the least amount was cypermethrin (183.09 µg g-1 dw). However, cypermethrin was the active substance that presented the lowest body burdens, and therefore required a lower dose to cause death of D. mexicanus adults. Our results demonstrate that prolonged presence of bifenthrin in the forest ecosystem could lead to bioaccumulation in soil, sediment, and insects.
Assuntos
Besouros , Inseticidas , Piretrinas , Traqueófitas , Animais , Bioacumulação , Ecossistema , Insetos , Inseticidas/análise , Inseticidas/toxicidade , México , Casca de Planta/química , Piretrinas/toxicidade , Solo , Testes de Toxicidade , ÁguaRESUMO
Chloroquine (CQ) has been widely used for many years against malaria and various viral diseases. Its important use and high potential to being persistent make it of particular concern for ecotoxicological studies. Here, we evaluated the toxicity of CQ alone and in combination with copper (Cu) to the euryhaline rotifer Proales similis. All experiments were carried out using chronic toxicity reproductive five-day tests and an application factor (AF) of 0.05, 0.1, 0.3, and 0.5 by multiplying the 24-h LC50 values of CQ (4250 µg/L) and Cu (68 µg/L), which were administered in solution. The rate of population increase (r, d-1) ranged from 0.50 to 52 (controls); 0.20 to 0.40 (CQ); 0.09 to 0.43 (Cu); and -0.03 to 0.30 (CQ-Cu) and showed significant decrease as the concentration of both chemicals in the medium increased. Almost all tested mixtures induced synergistic effects, mainly as the AF increased. We found that the presence of Cu intensifies the vulnerability of organisms to CQ and vice versa. These results stress the potential hazard that these combined chemicals may have on the aquatic systems. This research suggests that P. similis is sensitive to CQ as other standardized zooplankton species and may serve as a potential test species in the risk assessment of emerging pollutants in marine environments.
Assuntos
Cobre , Rotíferos , Animais , Cloroquina/toxicidade , Cobre/toxicidade , Dose Letal Mediana , Testes de Toxicidade CrônicaRESUMO
Although chydorids are the most diverse cladocerans in the world, there is still little information available related to their biology and even less with respect to their susceptibility to toxicants. Therefore, this work aimed to implement protocols with Alona guttata for acute, chronic, and sublethal toxicity tests, using the environmental concern toxicants deltamethrin (DM) and lead (Pb2+), which are commonly used due to agriculture and vector control or for the automotive industry, respectively. Once the results of LC50 (0.1160 ± 0.0107 µg/L for DM and 1.5797 ± 0.1605 mg/L for Pb2+) were obtained, sublethal concentrations (0.01 to 0.2 LC50) were used for the evaluation of biomarkers and chronic toxicity. Concentrations as low as 0.01 LC50 reduced Alona's survival and fecundity, negatively affecting demographic parameters, and decreased the energy reserves. A significant correlation was found between the natural rate of population increase and the caloric content, which demonstrates the suitability of these biomarkers as endpoints of early warning that allow inferring alterations at higher biological levels. Subsequently, this work could constitute the first report on the evaluation of the energy budget in a non-daphnid species, its alterations due to exposure to toxic substances and the correlation with demographic responses.
Assuntos
Cladocera/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Substâncias Perigosas/toxicidade , Chumbo/toxicidade , Nitrilas/toxicidade , Piretrinas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Cladocera/metabolismo , Relação Dose-Resposta a Droga , Fertilidade/efeitos dos fármacos , Dose Letal Mediana , Testes de ToxicidadeRESUMO
Vinclozolin (VZ) is a dicarboximide fungicide widely used on fruits, vegetables and wines, effective against fungi plagues. In this study we characterized the effects of VZ using a 4-day reproductive chronic assay with the freshwater rotifer Brachionus calyciflorus. The assay included observations of several features of asexual and sexual reproduction. Our results indicate that VZ: (a) increased asexual and sexual reproduction, (b) caused severe abnormality in females and (c) these abnormalities were inherited by sexual and asexual reproduction. At 1.2 mg/L three abnormal females were found out of 457 total females (0.66 %). This low percentage is consistent and reproducible according to further analysis, where we increased the number of replicates and total females exposed to 1.2 mg/L of VZ, and found 18 abnormal females out of 2868 total females (0.63 % abnormality). Interestingly, abnormal females found at 5.6 mg/L VZ exposure, were able to show mating behavior. Our results suggest that VZ behaves as a strong endocrine disruptor whose effects show the characteristic inverted-U-shape exposure concentration response curve regarding the intrinsic population increase and the percentage of abnormalities as endpoints.
Assuntos
Disruptores Endócrinos/toxicidade , Oxazóis/toxicidade , Rotíferos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Feminino , Fungicidas Industriais/toxicidade , Masculino , Microscopia Acústica , Reprodução/efeitos dos fármacos , Reprodução Assexuada/efeitos dos fármacos , Rotíferos/genética , Rotíferos/ultraestruturaRESUMO
Data regarding the effects of binary metal mixtures in marine zooplankton are scarce, particularly for rotifers. We examined the toxicity of 21 binary equitoxic mixtures of As, Cd, Cu, Fe, Hg, Pb, and Zn on the euryhaline rotifer Proales similis. The toxic units (TU50) revealed that 20 of these binary mixtures exhibited synergistic effects (TU50 < 1.00). The AsHg mixture showed a strong antagonistic effect (TU50 = 2.39), whereas the HgCu interaction exhibited a significant synergistic effect (TU50 = 0.29) on P. similis. TU50 values were <0.60 in all cases that showed synergism (80 %). Regarding the MIXTOX analysis, 13 binary mixtures presented some level of synergism, while two mixtures presented only additivity. Results emphasize the need for environmental agencies to revise and readjust protection guidelines for marine biota in response to the evident synergistic effects occurring at metal mixtures concentrations below the current permissible limits.
Assuntos
Mercúrio , Rotíferos , Animais , Cádmio , Chumbo , Zinco/toxicidadeRESUMO
Organisms are usually exposed to mixtures of emerging pollutants in aquatic environments. Due to their widespread use and environmental relevance, the individual and combined effects of the drugs azithromycin (AZT) and ivermectin (IVM) on the freshwater rotifer Lecane papuana and the euryhaline rotifer Proales similis were investigated. Rotifers showed greater sensitivity to IVM compared to AZT. The LC50 values of IVM and AZT for L. papuana and P. similis were 0.163 and 0.172 mg/L, and 13.52 and 20.00 mg/L, respectively. Population growth rates, assessed in chronic toxicity assays, responded negatively to increasing concentrations of both toxicants, either individually or in combination. Our results revealed two distinct combined toxicity responses: a strong synergistic effect in the freshwater rotifer and a marked antagonistic impact of the AZT-IVM mixtures in the euryhaline rotifer.
Assuntos
Azitromicina , Água Doce , Ivermectina , Rotíferos , Poluentes Químicos da Água , Animais , Ivermectina/toxicidade , Ivermectina/análogos & derivados , Rotíferos/efeitos dos fármacos , Azitromicina/toxicidade , Poluentes Químicos da Água/toxicidadeRESUMO
Pollution in aquatic ecosystems has been increasing drastically worldwide changing their water quality. Therefore, species must be adapted to these new scenarios. In Aguascalientes City, four representative urban reservoirs contain lead in the water column and extremely high concentrations of sediments. Therefore, an analysis was conducted to evaluate the resilience of zooplankton species to lead exposure in each reservoir using dormant and organisms. Results demonstrated a decrease range from 57.5 to 22.5% in overall diapausing egg hatching rate, while survivorship rate also decreased from 98 to 54% when organisms were exposed to the water of the four reservoirs and increasing lead concentrations. When Pb exposure increased, results showed a global negative effect on both hatching rate (decreasing from 58 to 30% at 0.09 mg L-1) and survivorship levels (decreasing from 100% to 0.07% at 0.09 mg L-1). We provide Species Sensitivity Distribution for both water reservoir dilutions and lead concentration to analyze diapausing eggs hatching and survivorship of offspring in the presence of same polluted conditions or lead of the autochthonous species found in reservoirs. Furthermore, specific analysis with two populations of the cladoceran Moina macrocopa showed clear dissimilar hatching patterns that suggested a different adaptive mechanism. Niagara population shows a hatching rate of approximately 25% in the first two days of reservoir water exposure, while UAA population drastically increased hatching rate to 75% on exposure at day seven. We provide the first record of bioaccumulation in ephippia of M. macrocopa.
Assuntos
Cladocera , Resiliência Psicológica , Rotíferos , Poluentes Químicos da Água , Animais , Chumbo/toxicidade , Ecossistema , México , Poluentes Químicos da Água/toxicidade , Eutrofização , ZooplânctonRESUMO
In many aquatic invertebrates including monogonont rotifers, sex provides genetic variation and dormant stages that allows dispersal in time and space. While the reproductive biology of some solitary monogonont rotifer species is known, little is known concerning mating behaviors in colonial rotifers. Coloniality poses unique challenges to the typical mating behavior of solitary rotifers. For instance, most species engage in circling behavior, where the male swims in close proximity to the female. In colonial forms, access to a particular female may be hindered by nearby colony mates. Here we provide descriptions of (1) male morphology, (2) mating behavior, and (3) types of eggs of the widespread colonial rotifer Sinantherina socialis, and discuss modifications in mating strategies as a consequence of coloniality. Two important differences from mating patterns documented in solitary rotifers were found in S. socialis. First, duration of circling phase of mating is protracted for males encountering small colonies of females as compared to solitary females. Males encountering single females removed from their colonies behave similarly to those of solitary species. Second, duration of copulation in S. socialis is the shortest reported for any rotifer species. Endogamy might occur in this species as sons copulate with their sisters and mothers, at least under laboratory conditions. Examples of behaviour in linked video clips.
RESUMO
The study of sexual reproductive behavior supported by ultrastructural evidence is important in rotifers to describe differences among potential cryptic species. In this research, the morphology of the rotifer Brachionus bidentatus is described at the ultrastructural level, using electronic microscopy, together with a brief description and discussion of its sexual reproductive behavior. The characteristics of the (a) male, (b) the female, (c) the sexual egg or cyst, (d) the partenogenic egg, (e) the no-fecundated sexual egg (male egg), and (f) the trophi, were described. Another part of this research is dedicated to the ultrastructure of the sex cells of the male rotifer B. bidentatus. Samples were obtained from La Punta pond in Cosio, Aguascalientes, Mexico (22 degrees 08' N - 102 degrees 24' W), and a culture was maintained in the laboratory. Fifty organisms, from different stages of the rotifer Brachionus bidentatus, were fixed in Formol at 4% and then prepared; besides, for the trophi, 25 female rotifer Brachionus bidentatus were prepared for observation in a JEOL 5900 LV scanning electronic microscope. In addition, for the observation of male sex cells, 500 males of Brachionus bidentatus were isolated, fixed and observed in a JEOL 1010 transmission microscope. Females of B. bidentatus in laboratory cultures had a lifespan of five days (mean+one SD = 4.69 +/- 0.48; N=13), and produced 4.5 +/- 3.67 (N=6) parthenogenetic eggs during such lifespan. In the case of non-fertilized sexual eggs, they produced up to 18 eggs (mean+one SD = 13 +/- 4.93; N=7). Sexual females produced a single cyst on average (mean +/- one SD = I +/- 0; N=20). For the sexual cycle, the time of copulation between male and female ranged from 10 to 40 seconds (mean +/- one SD = 17.33 +/- 10.55, N=7). The spermatozoa are composed of a celular body and a flagellum, the size of the body is of 300 nm while the flagellum measures 1 700nm. The rods have a double membrane. Their mean length is almost 2.45 microm +/- 0.74, N=6; and their mean wide is 0.773 microm +/- 0.241, N=11. The evidence on the specific ultrastructural characteristics of the rotifer B. bidentatus is notorious, even more in the male and in the cyst cell. Regarding the ultrastructure of the spermatozoa and the rods, compared to other species they only differ in size, despite their structural resemblance. Our study of the ultraestructure of this species adds useful information that along with molecular data will help clarify the taxonomy of brachionid rotifers.
Assuntos
Óvulo/ultraestrutura , Rotíferos/ultraestrutura , Espermatozoides/diagnóstico por imagem , Animais , Feminino , Masculino , México , Microscopia Eletrônica de Transmissão , Reprodução , Rotíferos/anatomia & histologia , UltrassonografiaRESUMO
We evaluated the multi-and transgenerational effects of single and combined environmentally relevant concentrations of glyphosate (GLY) and chlorpyrifos (CPF) in the estuarine rotifer Proales similis. The acute and chronic toxicities of GLY and CPF were determined as individual compounds and as a mixture. Rotifers were exposed to environmental concentrations of GLY (1, 10, 100, and 1000⯵g/L) and CPF (0.1, 1, 5, and 10⯵g/L). The main findings were as follows: (i) the LC50 values were 33.91â¯mg/L (GLY) and 280⯵g/L (CPF); (ii) the toxic unit (TU50) of the mixture was 0.30, corresponding to 10.17â¯mg/L GLY and 83⯵g/L CPF; (iii) the multigenerational study indicated that the tested concentrations of GLY and CPF, both single and combined, significantly and consistently decreased the growth rates of P. similis from the F0 to F6 generations; (iv) in most cases, GLY and CPF mixtures induced a strong synergistic effect; and (v) transgenerational effects were detected in the F4 generation, especially GLY and CPF in higher equitoxic proportions. These effects seem to dissipate in F5. Across multigeneration, a slight recovery could indicate population resilience to pollution. Our findings suggest that a mixture of GLY and CPF at environmental concentrations is likely to occur under real field conditions, increasing the risk to marine and estuarine invertebrates such as rotifers.
Assuntos
Clorpirifos , Rotíferos , Animais , Clorpirifos/toxicidade , Glicina/toxicidade , Dose Letal Mediana , GlifosatoRESUMO
Relative contributions of water- and methanol-soluble compounds and their hydrophobic/hydrophilic subfractions to the ROS (reactive oxygen species)-generating potential of ambient fine aerosols (D(p) < 2.5 µm) are assessed. ROS-generating (or oxidative) potential of the particulate matter (PM) was measured by the dithiothreitol (DTT) assay. Particles were collected on quartz filters (N = 8) at an urban site near central Atlanta during January-February 2012 using a PM(2.5) high-volume sampler. Filter punches were extracted separately in both water and methanol. Hydrophobic and hydrophilic fractions were then subsequently segregated via a C-18 solid phase extraction column. The DTT assay response was significantly higher for the methanol extract, and for both extracts a substantial fraction of PM oxidative potential was associated with the hydrophobic compounds as evident from a substantial attenuation in DTT response after passing PM extracts through the C-18 column (64% for water and 83% for methanol extract; both median values). The DTT activities of water and methanol extracts were correlated with the water-soluble (R = 0.86) and water-insoluble organic carbon (R = 0.94) contents of the PM, respectively. Brown carbon (BrC), which predominantly represents the hydrophobic organic fraction (referred to as humic-like substances, HULIS), was also correlated with DTT activity in both the water (R = 0.78) and methanol extracts (R = 0.83). Oxidative potential was not correlated with any metals measured in the extracts. These findings suggest that the hydrophobic components of both water-soluble and insoluble organic aerosols substantially contribute to the oxidative properties of ambient PM. Further investigation of these hydrophobic organic compounds could help identify sources of a significant fraction of ambient aerosol toxicity.
Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Material Particulado/análise , Espécies Reativas de Oxigênio/análise , Poluentes Químicos da Água/análise , Aerossóis/química , Poluentes Atmosféricos/química , Interações Hidrofóbicas e Hidrofílicas , Modelos Químicos , Material Particulado/química , Espécies Reativas de Oxigênio/química , Poluentes Químicos da Água/químicaRESUMO
Toxicity tests were performed on the freshwater rotifer Lecane quadridentata exposed to the pesticides carbaryl and methyl parathion (lethal, sublethal, and chronic) to compare the sensitivity between different endpoints: (a) 48-h mortality; (b) 30-min in vivo inhibition of esterase activity; (c) 5-day inhibition of the instantaneous growth rate. The emphasis of this work was to find the most appropriate endpoint to evaluate the toxicity of these pesticides in view of their sensitivity, duration, and ecological relevance. The comparison between the three toxicity tests show that the 5-day chronic tests have the lowest EC50 (2.22 and 6.6 mg/L), lowest-observed-effect concentration (2.5 and 2.5 mg/L), and no-observed-effect concentration (1.0 and 1.2 mg/L) values for carbaryl and methyl parathion, respectively. This indicates that the estimate of the instantaneous rate of natural increase r is the most sensitive endpoint regarding the toxicity of these pesticides. This sensitivity might be due to the effect on reducing the growth potential form the first generation on. Lethal and sublethal tests are closely related, suggesting that the immediate effect after inhibition of esterases is death. In general, the sensitivity of L. quadridentata is similar to other species of rotifers exposed to methyl parathion. Therefore, the 5-day chronic toxicity test with the freshwater rotifer L. quadridentata should be considered a good candidate to evaluate the effect of anticholinesterase pesticides, due to its high sensitivity and ecological relevance.
Assuntos
Carbaril/toxicidade , Inibidores da Colinesterase/toxicidade , Metil Paration/toxicidade , Praguicidas/toxicidade , Rotíferos/efeitos dos fármacos , Testes de Toxicidade , Animais , Determinação de Ponto Final , Esterases/farmacologia , Feminino , Água Doce , Rotíferos/crescimento & desenvolvimentoRESUMO
Wastewater discharges into freshwater bodies represent a serious ecological problem worldwide. In underdeveloped and developing countries wastewater treatment plants (WTP) only count with basic treatment, leading to the pollution of important aquatic reservoirs causing critical situations. In the present work, a one year evaluation of toxicity and main physical and chemical parameters of one of the major WTP of the state of Aguascalientes was conducted fortnightly, and to assess treatment alternatives for this WTP we tested: a) three white rot fungi (WRF), b) a photo-electrochemical process, c) ion-exchangers resins and activated carbon. The 3 WRF exhibited high COD removal from influents (72 - 95 %) but only Phanerochaete chrysosporium reached significant toxicity removals (70 and 55 %, for an influent and an effluent, respectively). Treatments with electrochemical advanced oxidation processes resulted with the highest toxicity and COD removals (96 % for both parameters) in comparison to biological and physicochemical treatments. Adsorption with activated carbon, zeolite and chelex ion-exchange resins removed 60 - 90 % of COD and 60 - 99 % toxicity. These results could be used to improve operation of the Industrial Park WTP and to plan future modifications to the plant.
Assuntos
Poluentes da Água/toxicidade , Animais , Daphnia/efeitos dos fármacos , Eletroquímica , Phanerochaete/metabolismo , Poluentes da Água/metabolismoRESUMO
Glyphosate levels and the transfer of glyphosate across trophic levels have rarely been studied in zooplankton. The food preferences of zebrafish during the first-feeding stage (which is critical for the survival of organisms), were analyzed because of the requirement for live food. Larval survival begins to be affected when glyphosate intake exceeds 0.3666 µg/larvae/day, in the case that only the food is contaminated; if the medium is also contaminated, the effects on survival start from 0.2456 µg/larvae/day. It was shown that glyphosate was more likely to be incorporated through the medium than through the food (zooplankton), which supports the results of previous studies that have ruled out the potential for biomagnification. The bioconcentration factor (BCF) of glyphosate was determined using an ELISA tests specific to measure glyphosate in the fish D. rerio, the rotifers Brachionus calyciflorus and Lecane papuana, and the cladoceran Ceriodaphnia dubia. The experimental design consisted in exposing seven zebrafish adults per replica (four replicates) in three treatments 1, 5, and 10 mg/L of glyphosate for 96 h to obtain bioconcentration factors in the gills, liver, and muscle. These concentrations were selected as potential glyphosate concentrations right after application as double highest reported concentration. Glyphosate levels in zooplankton can represent up to 6.26% of the total weight of rotifers (BFC = 60.35) and in zebrafish adult organs were less than 8 µg/mg of tissue (BCF values < 6). Although glyphosate does not biomagnify, our results suggest that glyphosate affected the dynamics between zooplankton and zebrafish larvae, diminishing survival and feeding rates, given that zooplankton species bioconcentrate glyphosate in large quantities. The BCF values found in this contribution are higher than expected. Glyphosate exposure affected energy metabolism and feeding behavior of zebrafish larvae, which presented high mortality rates at environmentally relevant concentrations.
Assuntos
Rotíferos , Poluentes Químicos da Água , Animais , Peixe-Zebra/fisiologia , Glicina/toxicidade , Rotíferos/metabolismo , Larva/metabolismo , Zooplâncton/metabolismo , Comportamento Alimentar , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/metabolismo , GlifosatoRESUMO
The inhibitory effects on esterases and phospholipase A2 (PLA2) in the freshwater rotifer Euchlanis dilatata, native to Mexico, were assessed by fluorimetry after in vivo exposure (30 min) in laboratory conditions to sublethal concentrations of metals and pesticides. EC(50) values for esterases ranged from 7.9 × 10(-7) for DDT to 61.9 µg l(-1) for methyl parathion, while corresponding values for PLA2 ranged from 0.96 × 10(-6) for mercury to 69.2 µg l(-1) for lead. These enzyme systems in E. dilatata are very sensitive to the tested agents and suggest they would be suitable biomarkers. However, sensitivity to other environmental contaminants should be investigated in laboratory conditions and field studies to assess their potential as environmental biomarkers.
Assuntos
Inibidores Enzimáticos/farmacologia , Enzimas/metabolismo , Metais Pesados/farmacologia , Praguicidas/farmacologia , Rotíferos/efeitos dos fármacos , Rotíferos/enzimologia , Poluição Química da Água/análise , Estruturas Animais/efeitos dos fármacos , Estruturas Animais/enzimologia , Animais , Animais Recém-Nascidos , Biocatálise/efeitos dos fármacos , Biomarcadores/metabolismo , Cádmio/farmacologia , Cádmio/toxicidade , DDT/farmacologia , DDT/toxicidade , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/toxicidade , Esterases/antagonistas & inibidores , Esterases/metabolismo , Corantes Fluorescentes/metabolismo , Chumbo/farmacologia , Chumbo/toxicidade , Dose Letal Mediana , Cloreto de Mercúrio/farmacologia , Cloreto de Mercúrio/toxicidade , Metais Pesados/toxicidade , Metil Paration/farmacologia , Metil Paration/toxicidade , Praguicidas/toxicidade , Inibidores de Fosfolipase A2 , Fosfolipases A2/metabolismoRESUMO
Acute toxicity tests with Cd, Pb, Hg, and methyl parathion were developed to compare the sensitivity of the rotifer Euchlanis dilatata with other model organisms used in aquatic ecotoxicology. Cd was the most toxic chemical (LC50 = 14.8 µg L(-1)), while methyl parathion was the least toxic (LC50 = 864.2 µg L(-1)). E. dilatata was more sensitive that other rotifer species, particularly of the genera Brachionus and Lecane. However, E. dilatata was less sensitive to mercury and methyl parathion than the crustacean, Daphnia magna. The high sensitivity of E. dilatata suggests that it may be an adequate benthic model to use in toxicity assessments of metal-contaminated sediments.
Assuntos
Monitoramento Ambiental/métodos , Rotíferos/efeitos dos fármacos , Testes de Toxicidade Aguda/métodos , Poluentes Químicos da Água/toxicidade , Animais , Cádmio/toxicidade , Daphnia/efeitos dos fármacos , Chumbo/toxicidade , Dose Letal Mediana , Mercúrio/toxicidade , Metil Paration/toxicidade , México , Especificidade da EspécieRESUMO
Application of pyrethroid pesticides and semiochemicals are two treatments used worldwide to control conifer bark beetles (Dendroctonus spp.); their residues can reach water reservoirs and water currents through run off and affect non-target organisms such as freshwater invertebrates. Therefore, we assessed the 48-h lethal toxicity, chronic toxicity (reproduction inhibition), and bioaccumulation of three pyrethroid pesticides (bifenthrin, cypermethrin, and deltamethrin) and two semiochemicals (verbenone and 3-methyl-2-cyclohexen-1-one) in two freshwater invertebrates: the cladoceran Alona guttata and the rotifer Lecane papuana. Bifenthrin was the most toxic of the five chemical compounds tested followed by deltamethrin and then cypermethrin, which was the least toxic pyrethroid for both species. Semiochemicals were far less toxic than pyrethroids and verbenone was most toxic than 3-methyl-2-cyclohexen-1-one for both species. For the rotifer Lecane papuana, the pyrethroid with the highest Bioconcentration Factor was bifenthrin, and for the semiochemicals it was 3-methyl-2-cyclohexen-1-one. For the cladoceran Alona guttata, the pyrethroid with the highest bioconcentration factor was cypermethrin and for the semiochemicals it was verbenone. The pyrethroid with highest body burdens both lethal and chronic was cypermethrin. Semiochemicals showed lethal and chronic body burdens 12-fold higher than pyrethroids and were therefore less toxic than pyrethroids. These results showed that the semiochemicals verbenone and 3-methyl-2-cyclohexen-1-one are a safe tool for the freshwater invertebrates tested when compared with pyrethroid pesticides. Cypermethrin was the least toxic of the pyrethroids tested and therefore could be considered as a good candidate to control outbreaks of the conifer bark beetle.
Assuntos
Besouros , Inseticidas , Praguicidas , Piretrinas , Traqueófitas , Poluentes Químicos da Água , Animais , Surtos de Doenças , Inseticidas/análise , Praguicidas/toxicidade , Feromônios , Casca de Planta/química , Piretrinas/toxicidade , Poluentes Químicos da Água/análiseRESUMO
Forty-eight hours acute toxicity tests were employed with Daphnia magna and Lecane quadridentata to assess the influents and effluents of the seven most important wastewater treatment plants (WTP) in the state of Aguascalientes, Mexico, during the 2006 dry and rainy seasons. The WTP of the City of Aguascalientes treated 1948 Ls(-1). The remaining six plants treated wastewater in the range from 28 to 93 Ls(-1). Plants efficiently removed toxicity when Daphnia magna was used as a model organism, but performed poorly when the freshwater rotifer Lecane quadridentata was employed. It was observed that biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), conductivity, dissolved oxygen (DO), pH, phenol, methylene blue active substances (MBAS), temperature, and total suspended solids (TSS) were within the maximum allowed levels (MAL) in the effluents during the rainy season. Whereas the BOD(5), total nitrogen, total dissolved solids (TDS) and TSS showed levels greater than the MAL in effluents during the dry season. The levels of BOD, MBAS, and total nitrogen were greater than the MAL in influents. In contrast, the values of TDS and TSS in influents were above the MAL during the rainy season. In the dry season the levels of aluminum (Al), iron (Fe), zinc (Zn), manganese (Mn), chromium (Cr), mercury (Hg) and lead (Pb) in influents and Fe, Mn and Pb in effluents were above the MAL. During the rainy season the levels of Mn, Cr and Hg in influents and those of Mn in effluents were above the MAL. When D. magna was used as model organism, acute toxicity units (aTU) for influents ranged from 0.2 to 4.4 and from 0.1 to 0.2 for effluents. These values for effluents are acceptable according to international guidelines. However, when L. quadridentata was the model organism, ranges were from 2.0 to 8.3 aTU in influents and from 1.6 to 2.6 aTU in effluents. The treated water that discharges into the San Pedro River would be considered toxic. The results of the toxicity tests demonstrated that the freshwater rotifer Lecane quadridentata was more sensitive (in 89.3% of the samples) than the cladoceran Daphnia magna when both organisms were exposed to the influents and effluents of the wastewater treatment plants.
Assuntos
Daphnia/efeitos dos fármacos , Metais Pesados/toxicidade , Rotíferos/efeitos dos fármacos , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/toxicidade , Abastecimento de Água/análise , Animais , Daphnia/fisiologia , Monitoramento Ambiental , Metais Pesados/análise , México , Oxigênio/análise , Consumo de Oxigênio/efeitos dos fármacos , Rotíferos/fisiologia , Esgotos , Testes de Toxicidade , Poluentes Químicos da Água/análiseRESUMO
Metals are widely used in modern society harming the environment; their toxicity cause environmental adverse effects to many organisms including zooplankton. This contribution employed: (a) acute and chronic toxicity tests, (b) epifluorescence image analysis, and (c) atomic absorption techniques, to analyze toxicity of four trace (copper, iron, nickel, and zinc), and one non-trace metals (mercury) on the freshwater rotifer Euchlanis dilatata. This work integrated results of Bioconcentration Factors (BCF's), sites of entry and accumulation and to determine mechanisms of uptake and toxicity of these five metals of the freshwater rotifer Euchlanis dilatata. This integral analysis enhanced our understanding of knowledge on: (a) the toxicity mechanisms, (b) sites of metal entry and concentration inside the rotifer, (c) bioconcentration and body burdens. As expected, Hg the non-trace metal used here, was the most toxic. Our results suggest that the toxicity is ameliorated in the rotifer by selecting feeding avoiding the most toxic particles and reducing adverse effects on reproduction, until mortality per se reduces reproduction. The chronic effect on ingestion rate was quite sensitive for all metals whereas reproduction was slightly affected. The combination of acute and chronic tests and determination of BCF's for each metal allowed calculation of the acute and chronic body burdens. Body burdens again confirmed that mercury was the most toxic metal of the five employed here.