In the 1940s, Xeropicta derbentina was introduced to the Provence region in south-eastern France. Since then, it has coexisted sympatrically with the native species Theba pisana. X. derbentina‘s successful establishment in Provence is commonly attributed to the hot and dry climate there. In the context of continually rising temperatures and increasing aridity resulting from global change, we conducted open-top chamber (OTC) experiments with both species to simulate extreme heat conditions to be expected in the context of climate change. After exposure in the OTCs, the temperatures on the shell surface did not differ between the two species. Nevertheless, differences in the survival of the species following heat shocks, which were induced by transferring the snails to the hot soil, were striking. An initial heat shock at the start of the OTC exposure was survived significantly better by T. pisana than by X. derbentina. However, the prevailing conditions in the OTC apparently weakened T. pisana to such an extent that only few individuals survived another heat shock a week later. In contrast, X. derbentina exhibited heat hardening induced by the OTC conditions, meaning that a heat shock after a week of adaptation to the OTCs resulted in much lower mortality than in individuals of the same species that had not adapted to OTC conditions before the heat shock. After a week of exposure to OTCs, the survival rate following heat shock was also significantly higher in X. derbentina than in T. pisana. These results suggest that X. derbentina will have a selective advantage over T. pisana as their environment continues to warm up unless more heat-tolerant phenotypes of the latter species evolve or immigrate.

Electrical stunning is a humane euthanasia method for larval zebrafish, and a suitable euthanasia protocol has recently been established. Here, we assess the associated stress response and tissue integrity. When compared to MS-222 overdose and hypothermia, electrical stunning caused no significant Hsp70 increase. Brain tissue was preserved and muscle tissue affected only slightly. Our results support the suitability of electrical stunning for humane euthanasia and artifact-free post-mortem analyses.

Although chronic contamination by silver ions (Ag+) can persist in aquatic systems over long periods of time and can therefore have an impact on population developments, regulatory testing commonly relies on single-generation endpoints. Here, we used Daphnia magna to quantify long-term effects of pg/L to ng/L concentrations of Ag+ across generations and to test whether recovery depends on exposure history. Using 21 d life-cycle assays over up to seven consecutive generations, we quantified survival, key life-history traits, and population fitness (intrinsic rate of natural increase, r). In our study, low environmental concentrations of Ag+ caused minimal mortality, but sublethal effects persisted or multiplied over generations. Notably, continuous exposure led to significant reductions in body length and r at 50 pg/L (nominal LOEC) by the fourth generation exposed, representing population-relevant effects of Ag+ at very low concentrations which should be given consideration in the assessment of both water quality and the chemical itself. Recovery was concentration-dependent: low-concentration-exposed lineages recovered within a few generations, whereas 15 ng/L exposure resulted in persistent deficits even through the recovery period of three generations. Exposure-history patterns indicated that long-term outcomes were dominated by the cumulative number of exposed generations. These findings highlight the limitations of acute and single-generation assays and emphasize the importance of considering information on the effects of chemicals, including Ag+, across multiple generations in risk assessments. They also highlight the need to include expectations regarding recovery after the removal of pollutants in these assessments.

Azoxystrobin, a widely used strobilurin fungicide, poses a potential risk to aquatic ecosystems due to its frequent detection in surface waters. Although its toxicity to non-target organisms has been extensively studied under standardized conditions, few investigations have considered how environmental factors can modulate the adverse effects of this chemical. In this study, we examined the toxicity of azoxystrobin to zebrafish (Danio rerio) embryos under different pH (5, 7, 9) and temperature (21 °C, 26 °C, 31 °C) conditions. Embryos were exposed to azoxystrobin concentrations ranging from 0 to 1000 μg/L, and endpoints such as survival, hatching rate, heart rate, malformations, developmental delay, and Hsp70 expression were assessed over 96 h post-fertilization. Our results demonstrate that azoxystrobin induces significant malformations (including edema, eye, tail, and spinal defects) and developmental delays at 1000 μg/L across all environmental conditions. Furthermore, both pH and temperature were found to modulate azoxystrobin toxicity: elevated temperature and alkaline pH partly alleviated mortality at high concentrations. The hsp70 expression patterns revealed complex interactions between the effects of the chemical and environmental factors. These findings highlight the importance of incorporating environmental variables into ecotoxicological risk assessments of pesticides to better reflect realistic exposure scenarios and potential ecological impacts.

Pharmaceuticals and their metabolites are increasingly detected in aquatic ecosystems, raising concerns about their environmental impact. Most of them, including ibuprofen (IBU), are ionizable organic compounds (IOCs). Their chemical speciation depends on the pH of the surrounding environment, with neutral species having greater permeability and potentially higher toxicity. Τhe pH-dependent toxicity of IBU has been observed, with the lowest LC50 values at pH 5. Also, the effect of pH on the uptake and bioaccumulation of IBU in zebrafish (Danio rerio) embryos (ZFE) was investigated, highlighting the importance of considering pH in toxicokinetic studies. Slight variations in internal concentrations of IBU (Cint) were detected among samples at different pH values, whereas bioconcentration factors (BCFs) were higher under acidic conditions. Biotransformation of IBU was investigated through suspect and non-target screening workflows, utilizing liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). This is the first comprehensive study investigating the biotransformation of IBU in ZFE, and hydroxylation and taurine-conjugation were identified as primary pathways. Biotransformation affects the Cint of IBU since variations in Cint among the samples were further reduced when the concentrations of biotransformation products (bio-TPs) were considered (Cint-total). Future studies could greatly benefit from considering the biotransformation of IOCs for a better interpretation of toxicity and bioaccumulation in aquatic organisms.

The increasing use of chemicals has led to the integration of the bioconcentration factor (BCF) into chemical regulation. A machine learning model trained on chemical properties and test conditions for 962 chemicals enabled us to estimate experimental BCFs in 16 fish species with up to 90% accuracy. We showed that the BCF is not, as generally assumed, a fixed chemical-specific criterion, but increases with lower exposure concentration and longer exposure duration. A review of 165 regulatory studies submitted to EU authorities showed that about half of the chemicals that should have been classified as bioaccumulative according to worst-case criteria defined in our study were not so classified based on the experimental BCFs submitted. We therefore propose the implementation of two new objective metrics, BCF50 for minimum requirement bioaccumulation screening and BCF90 as a realistic worst-case surrogate, into regulation.

Silver (Ag) is widely released into aquatic environments through industrial and municipal discharges, with concentrations often reaching toxic levels for aquatic organisms. Its further extensive use in antimicrobials, especially during the COVID-19 pandemic, has increased environmental inputs. As Ag+ is the most toxic form of Ag, understanding its ecological risks remains critical for environmental regulation and ecosystem protection. Thus, we investigated multigenerational and transgenerational toxicity of Ag+ as AgNO3 on the ecologically important species midge Chironomus riparius using two complementary long-term life-cycle experiments. Experiment 1 simulated exposures with pulsed high environmentally relevant concentrations and recovery phases (nominal 3 µg/L), while Experiment 2 assessed continuous low environmentally relevant concentrations (nominal 0.01, 0.1, 1 and 3 µg/L) across four exposed generations of C. riparius followed by three recovery generations. Endpoints included survival, development, reproduction, growth as well as the population growth rate (PGR). Continuous Ag+ exposure produced cumulative increases in mortality and declines in emergence, reduced fertility and eggs per rope, delayed development (especially in females), and progressive reductions in PGR. Notably, adverse effects emerged or intensified over generations and were detectable at very low concentrations: some reproductive and survival endpoints showed significant impairment at the European Union’s environmental quality standard (EU-EQS) level (0.01 µg/L) by the fourth generation, while transgenerational effects persisted at ≥0.1 µg/L. Partial recovery occurred after removal of contamination at the lowest concentrations but not after higher exposures. The present study not only indicates that chronic, low-level Ag+ contamination can produce persistent, population-level adverse impacts on C. riparius, but also underscores the necessity for long-term ecological assessments to establish more protective standards and maintain ecosystem stability.

Background Glyphosate is a broad-spectrum, non-selective systemic herbicide with a commonly assumed low potential for accumulation in biota. Nevertheless, glyphosate has been shown to bioaccumulate in the tissues of several organisms. To understand the bioconcentration dynamics of glyphosate in fish, brown trout ( Salmo trutta forma fario ) of different age were exposed to different concentrations of glyphosate, the formulation Roundup® LB Plus, and the major transformation product aminomethylphosphonic acid (AMPA) for two, three, or four weeks at different temperatures in the laboratory. Mortality rates were determined, and tissue samples were collected at the end of the experiment to ascertain concentrations of glyphosate and AMPA residues by liquid chromatography coupled to mass spectrometry (LC–MS/MS). Results Brown trout mortality during exposure to glyphosate or AMPA was considerably higher at 15 °C than at 7 °C. Also, a significant increase in glyphosate concentrations in samples containing muscle, head, backbone, and caudal fin tissue with increasing exposure concentrations and temperatures was observed. Six-month-old fish contained more glyphosate per kg wet weight after exposure than ten-month-old fish. The bioconcentration factors (BCFs) for glyphosate and AMPA were much higher at 15 °C than at 7 °C, but in both cases decreased with higher glyphosate concentrations. The BCF for glyphosate formulated in Roundup® was higher than the one for the parent compound. Approximately 30–42% of the organ-absorbed glyphosate and AMPA remained in the tissues even when the fish were kept in clean water lacking the test substances for three weeks after termination of exposure. Conclusion Our study demonstrated that there is an interaction between glyphosate and ambient temperature in terms of toxicity. Further it was shown that increasing concentrations of glyphosate and AMPA in the surrounding media lead to significantly increased concentrations of these substances in brown trout tissues, although neither bioconcentration nor bioaccumulation of glyphosate in animal tissues is expected due to the high water solubility of this chemical. As a consequence, the uptake of glyphosate by humans through the consumption of contaminated edible fish is very likely.

In the present study, the toxicity of nicosulfuron to Danio rerio embryos was evaluated in three experiments through standardized toxicity tests according to OECD TG236 guidelines. In the first experiment, six concentrations of nicosulfuron (0, 0.1, 1, 10, 100, 1000 mg/L) were tested under optimal conditions (26 °C, pH 7.0) to assess the general sensitivity of zebrafish embryos to nicosulfuron. The second and third experiment examined the effects of different pH levels (5.0 and 9.0) and temperatures (21 °C and 31 °C) on the toxicity at four nicosulfuron concentrations (0, 10, 100, 1000 mg/L). Additionally, the sub-organismic effects of nicosulfuron on stress protein levels (Hsp70) of fish embryos were analyzed. Throughout the embryo experiments, no malformations were observed in all experiments. The survival rate exceeded 80% in all groups except for the 21 °C (pH 7.0) treatment groups. No significant effect of nicosulfuron on the survival rate was found at the same temperature or pH (p > 0.05). No significant difference in the heart rate was found among all nicosulfuron groups (p > 0.05) at 21 °C. The heart rate of fish embryos at 31 °C, pH 5.0 and pH 9.0 increased with nicosulfuron concentrations. Except for the pH 5.0 (26 °C) and 21 °C (pH 7.0) treatment groups, nicosulfuron was found to increase the hatching rate of embryos in other treatments; however, the corresponding times of action were different. At 21 °C (pH 7.0), the embryos did not hatch until 144 h post-fertilization. In terms of proteotoxicity, nicosulfuron was found to be more toxic to zebrafish embryos in the 21 °C, pH 5.0 and pH 9.0 treatment groups. However, at 31 °C, no significant difference in Hsp70 levels was found among all the different nicosulfuron concentrations (p > 0.05). Our results show that nicosulfuron exerts a weak toxicity to zebrafish embryos; however, this toxicity is amplified by inappropriate pH or temperature conditions.

Vom WasserVolume 122, Issue 2 p. 46-47 Kurzbeiträge Effektbasierte Methoden zur Effizienzkontrolle beim Ausbau von Kläranlagen mit einer vierten Reinigungsstufe Sabrina Schiwy, Corresponding Author Sabrina Schiwy [email protected] Frankfurt a. M. Dr. Sabrina Schiwy, Goethe Universität Frankfurt, Evolutionäre Ökologie und Umwelttoxikologie (E3T), Fachbereich 15, Campus Riedberg, Biologicum, Max-von-Laue-Straße 13, 60438 Frankfurt am Main E-Mail: [email protected]Search for more papers by this authorRita Triebskorn, Rita Triebskorn TübingenSearch for more papers by this author Sabrina Schiwy, Corresponding Author Sabrina Schiwy [email protected] Frankfurt a. M. Dr. Sabrina Schiwy, Goethe Universität Frankfurt, Evolutionäre Ökologie und Umwelttoxikologie (E3T), Fachbereich 15, Campus Riedberg, Biologicum, Max-von-Laue-Straße 13, 60438 Frankfurt am Main E-Mail: [email protected]Search for more papers by this authorRita Triebskorn, Rita Triebskorn TübingenSearch for more papers by this author First published: 17 June 2024 https://doi.org/10.1002/vomw.202400011AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume122, Issue2June 2024Pages 46-47 RelatedInformation

To elucidate how rising temperatures influence native amphipods, and how the expansion of wastewater treatment plants (WWTPs) with a fourth purification stage can alter temperature-related effects, studies were conducted in anthropogenically influenced rivers in Southwest Germany. Gammarids were sampled up- and downstream of two WWTPs, and exposed to elevated temperatures in the laboratory. Gammarids separated from precopula pairs were more sensitive to exposure-related stress and to a temperature increase than animals that were not in the reproductive phase. Furthermore, females were significantly more sensitive than males. Adult gammarids sampled individually at the WWTP with three purification stages showed a similar tolerance to elevated temperature at the up- and downstream site. In contrast, mortality following heat stress was substantially lower in animals sampled downstream of the WWTP with four treatment stages than in those sampled at the upstream site. We assume that the increased sensitivity of artificially separated precopula pairings reflect the situation under high hydraulic stress after heavy rainfall. Our results further illustrate the importance of WWTP upgrades in the context of climate change: gammarids sampled downstream the upgraded fourth-stage WWTP were likely exposed to lower levels of micropollutants, and thus may have allocated energy from detoxification to heat stress responses.

Glyphosate is used worldwide as a compound of pesticides and is detectable in many environmental compartments. It enters water bodies primarily through drift from agricultural areas so that aquatic organisms are exposed to this chemical, especially after rain events. Glyphosate is advertised and sold as a highly specific herbicide, which interacts with the EPSP synthase, an enzyme of the shikimate metabolism, resulting in inhibition of the synthesis of vital aromatic amino acids. However, not only plants but also bacteria can possess this enzyme so that influences of glyphosate on the microbiomes of exposed organisms cannot be excluded. Those influences may result in subtle and long-term effects, e.g., disturbance of the symbiotic interactions of bionts with microorganisms of their microbiomes. Mechanisms how the transformation product aminomethylphosphonic acid (AMPA) of glyphosate might interfere in this context have not understood so far. In the present study, molecular biological fingerprinting methods showed concentration-dependent effects of glyphosate and AMPA on fish microbiomes. In addition, age-dependent differences in the composition of the microbiomes regarding abundance and diversity were detected. Furthermore, the effect of exposure to glyphosate and AMPA was investigated for several fish pathogens of gut microbiomes in terms of their gene expression of virulence factors associated with pathogenicity. In vitro transcriptome analysis with the fish pathogen Yersinia ruckeri revealed that it is questionable whether the observed effect on the microbiome is caused by the intended mode of action of glyphosate, such as the inhibition of EPSP synthase activity.

Depending on the ambient pH, ionizable substances are present in varying proportions in their neutral or charged form. The extent to which these two chemical species contribute to the pH-dependant toxicity of ionizable chemicals and whether intracellular ion trapping has a decisive influence in this context is controversially discussed. Against this background, we determined the acute toxicity of 24 ionizable substances at up to 4 different pH values on the embryonic development of the zebrafish, Danio rerio, and supplemented this dataset with additional data from the literature. The LC50 for some substances (diclofenac, propranolol, fluoxetine) differed by a factor of even >103 between pH5 and pH9. To simulate the toxicity of 12 acids and 12 bases, six models to calculate a pH-dependant logD value as a proxy for the uptake of potentially toxic molecules were created based on different premises for the trans-membrane passage and toxic action of neutral and ionic species, and their abilities to explain the real LC50 data set were assessed. Using this approach, we were able to show that both neutral and charged species are almost certainly taken up into cells according to their logD-based distribution, and that both species exert toxicity. Since two of the models that assume all intracellular molecules to be neutral overestimated the real toxicity, it must be concluded, that the toxic effect of a single charged intracellularly present molecule is, on the average, lower than that of a single neutral molecule. Furthermore, it was possible to attribute differences in toxicity at different pH values for these 24 ionizable substances to the respective deltas in logD at these pH levels with high accuracy, enabling particularly a full logD-based model on the basis of logPow as a membrane passage descriptor to be used for predicting potential toxicities in worst-case scenarios from existing experimental studies, as stipulated in the process of registration of chemicals and the definition of Environmental Quality Standards (EQS).

Tire and road wear particles (TRWP), which contribute significantly to microplastic emission, are receiving more attention, but details about particle composition, translocation from source to sink, and particularly the possible effects on ecosystems are largely unknown. We examined the influence of native TRWP-containing sediments from two settling ponds on the mortality and behavior of the aquatic larvae of Chironomus riparius. Both sediments, whether pure or mixed with different proportions of quartz sand and suspended in water, led to increased mortalities with increasing concentrations and were shown to be oxygen consuming. Artificial aeration significantly reduced larval mortality in both sediments. Chironomid larvae show high tolerance to anoxic and polluted environments due to physiological and behavioral adaptations, such as the construction of vertical sediment tubes (chimneys), in which they create oxic compartments. A significant correlation was found between the proportion of contaminated sediment and the number of chimneys: the more contaminated sediment, the fewer chimneys were constructed. The number of chimneys per surviving larva decreased with an increased proportion of contaminated sediment in parallel to increased larval mortality. We hypothesize that contents of these sediments negatively impact the larvae’s ability to survive at low oxygen concentrations due to impairments of essential behavioral and physiological processes.

Climate change, biodiversity loss, and chemical pollution are planetary-scale emergencies requiring urgent mitigation actions. As these "triple crises" are deeply interlinked, they need to be tackled in an integrative manner. However, while climate change and biodiversity are often studied together, chemical pollution as a global change factor contributing to worldwide biodiversity loss has received much less attention in biodiversity research so far. Here, we review evidence showing that the multifaceted effects of anthropogenic chemicals in the environment are posing a growing threat to biodiversity and ecosystems. Therefore, failure to account for pollution effects may significantly undermine the success of biodiversity protection efforts. We argue that progress in understanding and counteracting the negative impact of chemical pollution on biodiversity requires collective efforts of scientists from different disciplines, including but not limited to ecology, ecotoxicology, and environmental chemistry. Importantly, recent developments in these fields have now enabled comprehensive studies that could efficiently address the manifold interactions between chemicals and ecosystems. Based on their experience with intricate studies of biodiversity, ecologists are well equipped to embrace the additional challenge of chemical complexity through interdisciplinary collaborations. This offers a unique opportunity to jointly advance a seminal frontier in pollution ecology and facilitate the development of innovative solutions for environmental protection.

As there is still little knowledge of interactions between microplastics (MP) and hydrophilic compounds, we propose ways the toxicity of hydrophilic pesticides can be modulated by MP, when sorption can be excluded. Larvae of Chironomus riparius were exposed to thiacloprid (TH, 1 µg/L) and polystyrene microplastic particles (PS; <50 µm; 150,000 and 1,000,000 particles/L) for 96 h, solely or in co-exposure. Burrowing behavior and mortality were observed. Larvae in treatments containing PS established themselves quicker in the sediment and kept the ability to rebury for a longer time compared to control and TH, respectively. While TH elevated the mortality, exposure to PS alone did not affect the survival of the larvae. In co-exposure of TH and PS, a concentration of 150,000 particles/L significantly reduced the toxicity of 1 µg/L TH after 96 h, an effect that was not observed at 1,000,000 particles/L. Therefore, we hypothesize that this modulation of the toxicity of TH eventually may have resulted from a combination of a ‘protective MP layer’ in the gut and a higher retention time of particles in larvae exposed to 150,000 particles/L than in those exposed to 1,000,000 particles/L due to the lower number of ingestible particles in the former.

Leverett et al. commented on the Environmental quality standard (EQS) for diclofenac derived under the European Water Framework Directive [Leverett et al. (2021) Environ Sci Eur 33: 133 https://doi.org/10.1186/s12302-021-00574-z]. They postulated that the derivation of the EQS value for diclofenac is not conducted according to the EQS Technical Guidance, but rather using data of poor reliability and relevance. Consequently, the authors suggested using their alternative derived value instead. It is to be noted that the process for the EQS derivation for diclofenac is still ongoing and not finalized, and that as a consequence, any critical analysis is very premature. In general, within the current European Commission process, EQS values proposals are derived by expert groups led by the Joint Research Centre. In the specific case for diclofenac, Leverett et al. have also been actively involved as experts. This response to Leverett et al. (2021) aims to clarify the reasoning behind the proposal from a scientific point of view and to express our concern for the lack of transparency of their position in the statement of competing interests. Indeed, the authors did not disclose their participation in the expert group for deriving the diclofenac EQS value, nor that they have direct and indirect ties to a company that markets diclofenac in Europe, Glaxo Smith & Kline plc (GSK). This amounts to a significant conflict of interest and leads to disinformation to the reader.

Pharmaceuticals such as antidepressants are designed to be bioactive at low concentrations. According to their mode of action, they can also influence non-target organisms due to the phylogenetic conservation of molecular targets. In addition to the pollution by environmental chemicals, the topic of microplastics (MP) in the aquatic environment came into the focus of scientific and public interest. The aim of the present study was to investigate the influence of the antidepressant amitriptyline in the presence and absence of irregularly shaped polystyrene MP as well as the effects of MP alone on juvenile brown trout (Salmo trutta f. fario). Fish were exposed to different concentrations of amitriptyline (nominal concentrations between 1 and 1000 µg/L) and two concentrations of MP (104 and 105 particles/L; <50 µm) for three weeks. Tissue cortisol concentration, oxidative stress, and the activity of two carboxylesterases and of acetylcholinesterase were assessed. Furthermore, the swimming behavior was analyzed in situations with different stress levels. Exposure to amitriptyline altered the behavior and increased the activity of acetylcholinesterase. Moreover, nominal amitriptyline concentrations above 300 µg/L caused severe acute adverse effects in fish. MP alone did not affect any of the investigated endpoints. Co-exposure caused largely similar effects such as the exposure to solely amitriptyline. However, the effect of amitriptyline on the swimming behavior during the experiment was alleviated by the higher MP concentration.