Ecotoxicology最新文献

The use of some organophosphate insecticides is restricted or even banned in paddy fields due to their high toxicity to aquatic organisms. The aim of this study is to elucidate the main pathways and target organs of organophosphate insecticide toxicity to fish exposed via different routes by integrating histopathological and biochemical techniques. Using malathion as the model drug, when the dosage is 20-60 mg/L, the toxicity of whole body and head immersion drugs to zebrafish is much higher than that of trunk immersion drugs. A dose of 21.06-190.44 mg/kg of malathion feed was fed to adult zebrafish. Although the dosage was already high, no obvious toxicity was observed. Therefore, we believe that the drug mainly enters the fish body through the gills. When exposed to a drug solution of 20 mg/L and 60 mg/L, the fish showed significant neurological behavioral abnormalities, and the pathological damage to key organs and brain tissue was the most severe, showing obvious vacuolization and the highest residual amount (8.72-47.78 mg/L). The activity of acetylcholinesterase was the most inhibited (54.69-74.68%). Therefore, brain tissue is the key toxic target organ of malathion in fish. In addition, we compared the bioaccumulation effects of different water-soluble organophosphorus insecticides in fish and their toxic effects. We found that the higher the water solubility of organophosphorus insecticides, the lower their toxicity to fish.

Assessing the effects of multigenerational exposure of aquatic animal populations to chemical contamination is essential for ecological risk assessment. However, beyond rare examples reporting the sporadic emergence of a toxicological tolerance within populations that persist in contaminated environments, conclusive results are even more limited from field studies when it comes to the alteration of life-history traits. Here, we investigated whether long-term exposure to cadmium (Cd) influences size-related life-history traits (i.e., size at puberty, median adult size, maximum size) in Gammarus fossarum, a keystone species of European stream ecosystems. We studied 13 field populations of G. fossarum (cryptic lineage B) living in headwater rivers located in natural areas scattered at a large geographical scale and exposed to contrasted bioavailable Cd contamination levels due to different local geochemical backgrounds. We achieved a detailed description of the physical and physicochemical conditions of the river reaches investigated. Land-use parameters, hydrological characteristics (flow, slope, river width, flow structure, mosaic of substrates), and physicochemical conditions (temperature, conductivity, dissolved oxygen) were measured. Metallic bioavailable contamination was assessed using a standardized active biomonitoring procedure (Gammarus caging). Based on the field demographic census of the 13 populations, our results demonstrated that chronic Cd contamination significantly influences life-history in the G. fossarum species, with a significant reduction in all size traits of populations (size at puberty, median adult size, maximum size). In addition, we confirmed Cd-tolerance in contaminated populations during exposure tests in the laboratory. Various hypotheses can be then put forward to explain the modification of size-related life-history traits: a direct toxic effect of Cd, a cost of Cd-tolerance, or an adaptive evolution of life-history exposed to toxic pressure.

Two monophyletic Daphnia species (Daphnia magna and D. similis) were exposed to a sub-lethal concentration of Pb (50 µg/L) for nine generations under two food regimes (usual and restricted) and analyzed for acetylcholinesterase (AChE) activity, first reproduction delay, lifespan, and net reproductive rate (R0) at the subcellular, individual, and population levels, respectively. In the sixth generation, Pb-acclimated neonates were moved to clean media for three more generations to check for recovery. The net reproductive rate (R0) of D. magna was not affected by Pb. However, Pb stimulated reproduction, reduced lifespan, and decreased AChE activity. First reproduction delay and lifespan did not improve during the recovery process, suggesting a possible genetic adaptation. Food restriction reduced R0, lifespan, delayed hatching, and increased AChE activity; the opposite outcomes were observed for D. similis. The full recovery shown by R0 suggests the physiological acclimation of D. similis. Under food restriction, the animals exhibited a reduction of R0 and lifespan, delayed first reproduction, and increased AChE activity; however, there was no effect of Pb. The recovery process under food restriction showed that D. similis might not cope with Pb exposure, indicating a failed recovery. Such outcomes indicate that one model species' sensitivity may not represent another's sensitivity.

The present study was designed to assess the allelopathic potential of invasive weed Ageratina adenophora leaf extracts on seed germination and seedling development efficiency of native tree [viz. Quercus leucotrichophora A. Camus (Oak) and Pinus roxburghii Sarg. (Pine)] and crop [(Triticum aestivum L. (Wheat) and Lens culinaris Medik. (Lentil)] species of Kumaun Himalaya. Pot experiments were conducted in the glasshouse of the Botany Department, D.S.B. Campus, Kumaun University Nainital, following a Completely Randomized Block Design (CRBD) with three treatments (C₁-25%, C₂-50%, and C₃-100% of aqueous leaf extract) and one control, each with five replicates. The experiment lasted one year for tree species and continued until the seed maturation phase for crop species. Parameters such as seed germination proportion, root and shoot measurements, biomass, and crop productivity traits were recorded accordingly. Our bioassay results indicated that the inhibitory effect of leaf extracts on the measured traits of the selected native species was proportional to the applied extract concentrations of A. adenophora. Overall, lentil among crops and oak among tree species exhibited more inhibition compared to wheat and pine, respectively. At the highest concentration, reductions of 44%, 34%, 36%, and 24% in biomass production capacity were recorded for wheat, lentil, pine, and oak, respectively, while wheat and lentil productivity decreased by up to 33% and 45%, respectively. These results suggest that water-soluble allelochemicals produced by A. adenophora may impede the establishment of selected crop and tree species in agroecosystems and forest ecosystems invaded by this weed species. However, further studies on the characterization of phytochemicals and their specific role in seed germination and growth are warranted. Furthermore, the allelopathic potential of A. adenophora can be explored for the preparation of biopesticides and nature-friendly option to improve soil health, crop productivity, and reduce environmental pollution and management of this invasive weed.

Temperature can interact with chemical pesticides and modulate their toxicity. Sublethal exposure to pesticides is known to trigger hormetic responses in pests. However, the simultaneous effects of temperature and sublethal exposure to single or mixture-based insecticides on the insects' stimulatory responses are not frequently considered in toxicological studies. Here we investigated the combined effects of temperature on the lethal and sublethal responses of the green peach aphid Myzus persicae after exposure to commercial formulations of a neonicotinoid (thiamethoxam) and a pyrethroid (lambda-cyhalothrin) and their mixture. Firstly, the concentration-response curves of the insecticides were determined under four temperatures (15 °C, 20 °C, 25 °C, and 28 °C) by the leaf dipping method. Subsequently, the sublethal concentrations C₀, CL₁, CL₅, CL₁₀, CL₁₅, CL₂₀, and CL₃₀ were selected to assess sublethal effects on aphids' longevity and reproduction under the same temperatures. The results showed that the mixture of thiamethoxam + lambda-cyhalothrin caused greater toxicity to aphids compared to the formulations with each active ingredient alone and that the toxicity was higher at elevated temperatures. Furthermore, the exposure to low concentrations of the mixture (thiamethoxam + lambda-cyhalothrin) and the separated insecticides induced stimulatory responses in the longevity and fecundity of exposed aphid females, but the occurrence of such hormetic responses depended on the insecticide type, its sublethal concentration, and the temperature as well as their interactions.

Sea urchin species are ecologically important in the Gulf of California and are becoming popular as a local fishery due to their commercial value. The most abundant species are Echinometra vanbrunti, Eucidaris thouarsii, and Tripneustes depressus. The objective of this study was to evaluate cadmium, lead, copper, zinc, and iron concentrations, as well as stable isotope values in these sea urchin species in the Santa Rosalia mining area (STR), in three sites: Punta Gorda, Punta el Aterrizaje, and Punta Salina. The highest Fe concentration (100.2 mg kg^-1) was found in E. vanbrunti, while the highest concentrations of Pb (15.1 mg kg^-1), Cu (14.5 mg kg^-1), and Zn (347.7 mg kg^-1) were recorded in E. thouarsii, and the highest Cd concentration (10.8 mg kg^-1) was found in T. depressus. The main health risk of trace metal pollution in STR may be caused by Cd and Pb. δ¹⁵N and δ¹³C values were higher in E. thouarsii and T. depressus, respectively; E. thouarsii has the highest trophic position. Specimen size was not related to metal concentrations, but a positive relationship was observed between specimen size and isotopic values in T. depressus. The three species showed different bioaccumulation patterns for the metals analyzed. Additionally, collection sites and seasons play an important role in the variability of metal concentration.

Silver nanoparticles (AgNPs) are among the most produced nanomaterials in the world and are incorporated into several products due to their biocide and physicochemical properties. Since freshwater bodies are AgNPs main final sink, several consequences for biota are expected to occur. With the hypothesis that AgNPs can interact with environmental factors, we analyzed their ecotoxicity in combination with humic acids and algae. In addition to the specific AgNPs behavior in the media, we analyzed the mortality, growth, and phototactic behavior of Chydorus eurynotus (Cladocera) as response variables. While algae promoted Ag⁺ release, humic acids reduced it by adsorption, and their combination resulted in an intermediated Ag⁺ release. AgNPs affected C. eurynotus survival and growth, but algae and humic acids reduced AgNPs lethality, especially when combined. The humic acids mitigated AgNP effects in C. eurynotus growth, and both factors improved its phototactic behavior. It is essential to deepen the study of the isolated and combined influences of environmental factors on the ecotoxicity of nanoparticles to achieve accurate predictions under realistic exposure scenarios.

Reservoir construction promotes many environmental impacts, including the enhancement of mercury concentrations in fish. The processes that can influence mercury concentrations in fish in Amazonian reservoirs are still little explored in depth, especially when we consider the possible particularities of the ecosystems in question. This study aims to investigate how mercury concentrations in fish could be influenced by the Tucuruí dam, considering possible changes in their feeding and trophic position according to the dam position (up or downstream). Fish were sampled upstream and downstream of the Tucuruí reservoir, and total mercury (THg) and stable isotopes of carbon and nitrogen (δ¹⁵N and δ¹³C) were measured in muscles. We observed three different Hg bioaccumulation patterns influenced by the dam. These differences occurred due to species trophic niche changes corroborated by the isotope analysis. Higher THg concentrations downstream compared to those upstream ones were only observed for Geophagus proximus. On the contrary, Plagioscion squamosissimus, from downstream, presented lower concentrations than upstream ones. The isotopic niche of these two species presented different changes according to the sampled site. THg biomagnification was higher upstream compared to downstream, considering that the regression slope was approximately two times higher upstream versus downstream. THg concentrations in fish were explained by the differences in their feeding habits according to their location in relation to the dam. The difference in THg biomagnification was able to reflect differences in structure of the food web chain in ecosystems under the dam's influence.

Among aquatic organisms, filter feeders are particularly exposed to the ingestion of microplastics (MPs) and nanoplastics (NPs). The present study investigates the effect of environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized plastic debris collected in the Garonne River (France), and polystyrene NPs (PS NPs) on the freshwater bivalve Corbicula fluminea. Organisms were exposed to plastic particles at three concentrations: 0.008, 10, and 100 μg L^-1 for 21 days. Gene expression measurements were conducted in gills and visceral mass at 7 and 21 days to assess the effects of plastic particles on different functions. Our results revealed: (i) an up-regulation of genes, mainly involved in endocytosis, oxidative stress, immunity, apoptosis, and neurotoxicity, at 7 days of exposure for almost all environmental plastic particles and at 21 days of exposure for PS NPs in the gills, (ii) PS NPs at the three concentrations tested and ENV MPs at 0.008 μg L^-1 induced strong down-regulation of genes involved in detoxication, oxidative stress, immunity, apoptosis, and neurotoxicity at 7 days of exposure in the visceral mass whereas ENV MPs at 10 and 100 μg L^-1 and all ENV NPs induced less pronounced effects, (iii) overall, PS NPs and ENV MPs 0.008 μg L^-1 did not trigger the same effects as ENV MPs 10 and 100 μg L^-1 and all ENV NPs, either in the gills or the visceral mass at 7 and 21 days of exposure. This study highlighted the need to use MPs and NPs sampled in the environment for future studies as their properties induce different effects at the molecular level to living organisms.

Major tailings dam failures have occurred recently around the world and resulted in severe environmental impacts, such as metal contamination. Manganese is a metal highly associated with mining activities, largely detected in mining dam collapses. This metal is considered necessary for different organisms, but it can be toxic and cause oxidative stress and genetic damage in fishes. In this study, we investigated the toxic effects of manganese on Astyanax lacustris, by exposing the fish individually to different concentrations of this metal (2.11, 5.00, and 10.43 mg/L) for 96 h. To assess the effects of manganese, we used biochemical biomarkers (glutathione S-transferase, catalase, and acetylcholinesterase enzyme activity) and the manganese bioaccumulation in different tissues (liver and gills). The obtained data showed that only at concentrations of 5.00 mg/L and 10.43 mg/L the activity of glutathione S-transferase differed significantly. Additionally, the acetylcholinesterase activity in the brain tissue was inhibited. The highest level of manganese bioaccumulation was observed in the liver and branchial tissue. Overall, we concluded that high concentrations of manganese may cause physiological changes in Astyanax lacustris.