Search Results (55)

Humanity faces the great challenges arising from pollution and climate change which evidently lead to the irreversible effects observed on the planet. It is now more important than ever to monitor and safeguard the ecosystem as it has been highlighted by governments and scientists. Conventional approaches for water pollution rely on the detection of chemicals in the environment. However, these descriptive observations when compared against water quality standards used as metrics for pollution are unable to predict pollution early or capture the extent of its impact. This weakness is reflected in the legislation and the thresholds for emerging pollutants such as pharmaceuticals and nanomaterials. To bridge the gap and to understand the underlying mechanisms for toxicity, research in the field of molecular ecotoxicology shifts more and more towards the integration of model systems, in silico approaches and molecular information as endpoints. Focusing on the freshwater ecosystem, daphnids are key species employed in risk assessment which are characterised as highly responsive to pollutants and physical stressors. The translation of molecular information describing the physiology of these organisms provides novel and sensitive metrics for pollution assessment. Full article

This study explores the interaction between Prymnesium parvum and Daphnia magna under low-salinity conditions. P. parvum showed reduced growth below 0.4 PSU and peaked at 1.0 PSU within the tested 0.2–1.0 PSU range. D. magna, exposed to P. parvum across 0.0–6.0 PSU, experienced increased mortality at 4.0 and 6.0 PSU, but tolerated 0.0–1.0 PSU well and grazed actively on P. parvum without significant vitality loss. This range reflects conditions observed in the Oder River during the 2022 fish die-off. The count of P. parvum cells did not vary significantly across the 0.2 to 1.0 PSU range of salinities in D. magna presence, except at 0.6 PSU. All daphnids survived even at P. parvum densities of 1 × 10⁵ cells/mL, though increasing algal concentrations reduced juvenile growth rates. Direct observation under a microscope confirmed algal ingestion. Toxin accumulation in cells and medium likely reduced grazing efficiency via allelopathic effects. The study assessed whether D. magna can tolerate prymnesins while maintaining feeding under varying salinities. Results suggest that Daphnia magna could act as a biological suppressor of golden algae under certain environmental conditions, though further work is needed to quantify grazing efficiency and prymnesins concentrations. Full article

This study analyzes the acute toxicity of Zn²⁺, Cd²⁺, and Cu²⁺ on water fleas. The hatching rate of D. magna ephippia was monitored under the influence of the pollutant at concentrations of 0.1 mg/L, 0.2 mg/L, 0.3 mg/L, 0.4 mg/L, 0.5 mg/L, and 1.0 mg/L over an exposure period of 42 h−67 h. The mortality rate of newborns was determined comparing with the control sample at 12 h, 24 h, and 48 h, as well as with the lethal concentration 50% (LC50). The results showed that Zn²⁺ appears to be less toxic to D. magna compared to Cd²⁺ and Cu²⁺, even at high concentrations, suggesting a greater tolerance of the ephippia to this metal. Newborn mortality increased significantly with higher concentrations and longer exposure times, with Cd²⁺ causing mortality rates of up to 100% after 48 h. In contrast, Zn²⁺ exhibited lower toxicity, although mortality increased with high concentrations and extended exposure periods. Full article

The widespread application of antibiotics in intensive livestock production is increasingly contributing to antibiotic contamination, and their potential ecological risk to environmental media by resourceful utilization of livestock manure as fertilizers in China has been recognized. This study conducted a comprehensive investigation on 79 large-scale livestock farms and collected 86 livestock excrements and 20 soil and 20 surface water samples distributed in Sichuan Basin, where no similar studies were carried out before. In total, four tetracyclines (TCs), eight sulfonamides (SAs), and eight fluoroquinolones (QNs) were monitored by liquid chromatography–triple quadrupole mass spectrometry. The findings revealed that antibiotics occurrence varied remarkably in excrement (feces or manure) among different livestock farms and different livestock species, following the descending order as QNs > TCs > SAs of detection rates and as TCs > QNs > SAs of detected concentrations, respectively. By source apportionment, livestock manure was demonstrated as a possible source for TCs and QNs detected in soil, while the detection of antibiotics in surface water was probably related to other sources. The central, south, and southwest of Sichuan Basin displayed a higher contamination of antibiotics from livestock manure. The ecological risk of antibiotics was obtained from a medium to heavy level, particularly TCs from swine farms to green algae, water flea, and inflated duckweed in aquatic water and QNs from all livestock farms to sensitive organisms in soil. Overall, the prioritized resource utilization of livestock manure would probably increase the contamination level and ecological risk to environment; hence, rational and effective measurement was highly recommended for antibiotics prevention in some regions of Sichuan Basin. Full article

Integrated pest management based on the use of biopesticides is largely applied. Experimental bioassays are critical to assess biopesticide biosafety at the ecotoxicological level. In this study, we investigated the effects of the new Bacillus thuringiensis subsp. kurstaki (Btk)-formulated-based biopesticides BLB1 and Lip, efficiently tested in field assays (IPM-4-CITRUS EC project no. 734921) on two aquatic non-target organisms, precisely the water flea Daphnia magna and the bioluminescent bacteria Aliivibrio fischeri. Acute toxicity studies, carried out in a comparative manner with Delfin^® as the reference bioproduct and the lactose-based Blank formulation, show that no significant toxicity was observed up to 1 g/L. Our results indicated that BLB1- and Lip-formulated new bioproducts are far less toxic than the Delfin^® reference bioproduct. Full article

A novel magnetic composite made of Peruvian pyroclastic dust material decorated with maghemite nanoparticles was synthesized and characterized using a variety of analytic techniques. The 13 nm maghemite nanoparticles were grown on the pyroclastic dust using the conventional coprecipitation chemical route. A short-term acute assay was developed to study the ecotoxicological behavior of the water flea, Daphnia magna. A 24 h-lethal concentration (LC₅₀) value equal to 123.6 mg L⁻¹ was determined only for the magnetic composite. While the pyroclastic dust material did not exhibit a lethal concentration, it caused morphologically significant changes (p < 0.05) for heart and tail parameters at high concentrations. Morphologies exposed to the magnetic composite above the 24 h-LC₅₀ revealed less tolerance and significant changes in the body, heart, antenna, and eye. Hence, it affects biomarker growth and swimming. The reproduction rate was not affected by the raw pyroclastic dust material. However, the number of individuals showed a decrease with increasing composite concentrations. The present study indicates the LC₅₀ value, which can be used as a reference concentration for in-situ water cleaning with this material without damaging or changing the Daphnia magna ecosystem. Full article

The levels of pharmaceuticals have been continuously increasing in aquatic ecosystems over the past decade due to their extensive use in human and veterinary medicine. Traditional water monitoring methods have been proven insufficient to capture pollution due to pharmaceuticals because of sensitivity limits, their inability to monitor every pollutant, and their failure to provide mechanistic insights into the actions of pollutants. To combat this, new approach methodologies (NAMs) are increasingly introduced as supplementary tools that can provide sensitive metrics for pollution assessment. In addition, NAMs can bridge the gap in ecotoxicological information regarding mixtures of pharmaceuticals, which are more commonly found in aquatic ecosystems versus pharmaceuticals existing alone. In this context, freshwater sentinel species, such as the water flea known as daphnids, were used to assess the acute effects of a typical pharmaceutical mixture on various physiological and molecular responses. In addition to mortality, phenotypic and molecular endpoints such as ingestion rate and enzyme activity were measured to determine the impact of a cocktail of commonly prescribed pharmaceuticals. Specifically, diclofenac, metformin, gabapentin, amoxicillin, trimethoprim, and erythromycin were mixed in equal amounts and tested at 0.1, 1, and 10 mg/L. Results showed differences in mortality, a decrease in feeding, and changes in enzyme activities, thus supporting a distinct pattern in the physiological responses of daphnids Full article

Trivalent chromium (Cr(III)) is a contaminant with toxic activity. Its presence in waters and soils is usually related to industrial activities such as tanneries. The aim of this study was to compare the removal of Cr(III) in hydroponic solutions and tannery effluents using two floating macrophytes: Salvinia auriculata and Eichhornia crassipes. First, to determine the chromium removal capacity in solution and the bioaccumulation factor (BAF) in tissues of each plant, experiments were set up with contaminated solutions with Cr(III) concentrations of 2, 5, 10, 20, and 40 mg/L. Subsequently, both plant species were exposed to a primary tannery effluent contaminated with 12 mg/L of Cr(III) in order to study the removal capacity of organic and inorganic matter, as well as the acute toxicity in the water flea (Daphnia magna) and genotoxicity in zebrafish (Danio rerio). Tests carried out on nutrient solutions revealed that both plants have a high capacity for removing Cr(III) in solution. The BAF in tissues was higher in E. crassipes compared to S. auriculata. In the experiments with a tannery effluent, both species presented low nutrient and organic matter removal efficiency, but they showed good Cr(III) removal capacity, with average reduction values of 57% for S. auriculata and 54% for E. crassipes after 72 h of exposure. E. crassipes contributed most to the reduction in acute toxicity in D. magna, while S. auriculata did not show a similar effect. However, both plant species managed to reduce the genotoxicity marker in D. rerio when compared with the initial effluent and the control. Full article

The freshwater water flea (Daphnia magna Straus, 1820) is prey for numerous predators. Yet it possesses a wide range of strategies to defend itself against predation. The aim of this work is to investigate the defensive mechanisms employed by D. magna to reduce predation by the coelenterate Hydra viridissima, and two planarians, Polycelis felina and Dugesia gonocephala. To do this, we used a freshwater microcosm. An additional aim is to investigate interactions with the presence of the isolated endosymbiotic algae from green hydra, thus combining and observing the interaction of the zooplankton and microalgal component. Each experiment included five replicates (13.5 °C, 25 °C), in crystallizing glass containers (60 mL volume, 60 mm diameter, 35 mm height), including satiated (fed with larvae of Artemia salina) and starved predators, respectively (one or five individuals of a particular predator species in one microcosm). As the isolated microalgae are unique, we tracked the following three mechanisms of Daphnia defense for the first time including precisely this microalgal component: (i) grouping (visual magnification), i.e., two or more Daphnia holding together; (ii) the phenomenon of overproduction, i.e., any number of Daphnia in one container above the 10 initially added individuals; and (iii) accelerated movement (“bullet movement”), i.e., high-speed movements in particular microcosms. The results provide new information for a better understanding of the interspecific relationships in systems that include both zooplankton and microalgal components. Full article

Sodium metasilicate (SM) is a synthetic hazardous water-soluble salt used in industry as an active ingredient in household cleaning products. The impact of SM on the aquatic environment has been discussed worldwide, but its toxicity has not been well documented and researched. Studies have only been performed on a handful of aquatic organisms: algae, plants, blackworms, water fleas, dipteran larvae, and two fish species. Hydra is a simple freshwater cnidarian with diploblastic organisation, where all the cells are in permanent contact with the surrounding aqueous media, and represents a sensitive model organism for environmental toxicity assessments. This research aimed to determine and compare the effect of SM on the morphology, excitability, and behaviour of green and brown hydra and endosymbiotic microalgae as a microbiome of green hydra. The hydras were treated with four sublethal SM concentrations (0.050, 0.365, 0.380, and 0.390 g/L) for 72 h. Standard preparations were made for the cyto-histological analysis of green hydra, and damaged cellular layers and mesoglea and a changed distribution of microalgae were recorded. The SM caused muted responses to mechanical stimuli and damage to the tentacles in both hydra species. The changes were more pronounced in brown hydra, while green hydra showed better adaptability to unfavourable environmental conditions. Full article

The assessment of pollution is a serious issue and a major consequence of the overgrowing human population and its activities. Focusing on the aquatic ecosystem, traditional approaches of water chemistry mainly provide minimal monitoring with the detection of pollutants, while they fail to produce mechanistic or predictive insight. As such, effect-based methods have gained significant attention for the better mechanistic understanding of aquatic pollution. Among the key species used, daphnids have acquired a central position in aquatic toxicology and ecology. In this study, a novel feeding assay was developed and applied in a battery of exposures to different pollutants. Furthermore, in combination with biochemical markers and sensitive metabolomic analyses, the responses of daphnids following exposures were uncovered in molecular detail. Specific categories of metabolites were identified as significant indicators to predict pollution. Full article

The microcosm is a laboratory method frequently used in ecological studies related to population and food web interactions and environmental dynamics. It simultaneously brings into interaction different species in the same controlled laboratory experimental area and provides an opportunity for modeling and reconstruction of relationships in the natural biocenoses and ecosystems. We applied that approach to determine and improve our understanding of predator–prey interactions in different freshwater environments. The inhabitants of the microcosms were isolated endosymbiotic microalga Desmodesmus subspicatus (Chlorophyceae) (Chodat) Hegewald et Schmidt (CZ), green hydras, freshwater turbellarians, and large water fleas. Experiments were performed in five replicates, at 25 °C and 13.5 °C, with fed and hungry predators, respectively. Herein, we proposed a mechanism for microalgal hunting net formation in the freshwater microcosm. Ultrastructural visualization of the endosymbiotic microalgae revealed rod-like structures on the cell wall surface, structures that could possibly fit together and interconnect, suggesting the possibility of microalgal hunting net formation. Interspecific cooperation between isolated microalgae and turbellarians resulted in stronger hunting net formation in preying upon water fleas. This study contributes to the diversity of species interactions and shows the producers as a top link, as opposed to what is generally considered as a basic link in the food web, and presents the microalgae as triggers of the dynamics in the freshwater microcosm. Full article

Cabbage stem flea beetle (CSFB) is an important pest of oilseed rape that was controlled by neonicotinoid seed treatments until they were banned for this use in 2013. Since then, CSFB has been a difficult pest to control, partly due to widespread resistance to pyrethroid insecticides. Alternate solutions are necessary. Here, four entomopathogenic nematode (EPN) species were tested against CSFB adults under laboratory conditions. In addition, a bioassay was completed to test for EPN compatibility with a range of adjuvants (glycerin, xanthan gum and flame retardant) to protect EPNs from UV radiation and desiccation. Results show that EPNs have the potential to control CSFB adults under laboratory conditions. Heterorhabditis bacteriophora caused 75% CSFB mortality at a concentration of 4000 nematodes/mL after six days, Steinernema feltiae caused 80% CSFB mortality when applied at a concentration of 40,000 nematodes/mL after two days, Steinernema carpocapsae caused 85% mortality at a concentration of 10,000 nematodes/mL after six days, and Steinernema kraussei caused no more than 70% CSFB mortality overall compared to the water control, which led to 23% mortality. Steinernema feltiae and H. bacteriophora survival was 100% when exposed to adjuvants, except S. feltiae with glycerin and H. bacteriophora with flame retardant. Further research to evaluate the efficacy of EPN and adjuvants under field conditions is necessary. Full article

Neglected tropical diseases are known to be highly stigmatized conditions. This study investigates tungiasis-related stigma and control practices in the impoverished Napak District in rural northeastern Uganda, where tungiasis is hyperendemic and effective treatment is unavailable. We conducted a questionnaire survey with the main household caretakers (n = 1329) in 17 villages and examined them for tungiasis. The prevalence of tungiasis among our respondents was 61.0%. Questionnaire responses showed that tungiasis was perceived as a potentially serious and debilitating condition and that tungiasis-related stigma and embarrassment were common. Among the respondents, 42.0% expressed judging attitudes, associating tungiasis with laziness, carelessness, and dirtiness, and 36.3% showed compassionate attitudes towards people with tungiasis. Questionnaire responses further indicated that people made an effort to keep their feet and house floors clean (important tungiasis prevention measures), but lack of water was a common problem in the area. The most frequent local treatment practices were hazardous manual extraction of sand fleas with sharp instruments and application of various and sometimes toxic substances. Reliable access to safe and effective treatment and water are therefore key to reducing the need for dangerous treatment attempts and breaking the vicious cycle of tungiasis stigma in this setting marked by poverty. Full article