Our ability to anticipate and estimate how pollution affects biota is intrumental in the field of ecotoxicology. Impact of chemical pollution by metals, drugs or pesticides was widely studied in different species using acute and chronic scenarios. Since the ban on tributyltin in antifouling paints, other copper (Cu)-based paints are on the market, including a new generation of booster biocides:metal pyrithiones such as Cu pyrithione (CuPT). Pyrithione acts as a Cu ionophore facilitating Cu transport across the membranes. Although some data show their occurrence in aquatic ecosystems and few studies on the toxicity of CuPT in fish are published, major gaps in knowledge remain about their toxicity and toxic pathway. Few studies were previously conducted in animals exposed to CuPT pointing to reprotoxicity, developmental malformation and mortality (Li et al. 2021, Mochida et al., 2011; Mohamat-Yusuff et al., 2018, Shin et al., 2022). However, its toxicokinetic and toxicodynamic remain to be characterized in details. 

In this context, Bourdon et al. (2023) compared in juveniles of rainbow trout (Oncorhynchus mykiss), the effects of exposure to CuPT and ionic Cu2+ at equivalent Cu2+ molar concentrations. Presented data allow to compare the toxicity threshold, the accumulation of Cu and mechanisms of toxicity of both compounds. Acute and chronic exposures showed a higher bioaccumulation of Cu in the gills, and a higher toxicity of CuPT than that of ionic Cu2+, e.g. mortality , transcription levels of genes related to oxidative stress, detoxification and Cu transport. Intriguingly, the activities of enzymatic biomarkers used as proxy of antioxidant capacity were not significantly altered, although Cu is generally expected to trigger oxidative stress. In conlusion, this study brings new knowledge pointing that the presence of CuPT in the environment could induce toxic effects in non-target species. Moreover, it support the need to study in detail the toxicity of Cu-based paints to adapt regulations concerning their use and release in aquatic environments. Because of its low solubility in water, CuPT is expected to adsorb to suspended matter and food pellets. Future research should study this route of exposure.

References

Bourdon, C., Cachot, J., Gonzalez, P., Couture, P., 2023. Characterization of the bioaccumulation and toxicity of copper pyrithione, an antifouling compound, on juveniles of rainbow trout,  bioRxiv  ver. 3 peer-reviewed and recommended by Peer Community in Ecotoxicology and Environmental Chemistry. https://doi.org/10.1101/2023.01.31.526498

Li, X., S. Ru, H. Tian, S. Zhang, Z. Lin, M. Gao and J. Wang, 2021. Combined exposure to environmentally relevant copper and 2,2′-dithiobis-pyridine induces significant reproductive toxicity in male guppy (Poecilia reticulata). Science of the Total Environment 797, https://doi.org/10.1016/j.scitotenv.2021.149131

Mochida, K., Amano, H., Onduka, T., Kakuno, A., Fujii, K., 2011. Toxicity and metabolism of copper pyrithione and its degradation product, 2,2’-dipyridyldisulfide in a marine polychaete. Chemosphere 82, 390–397, https://doi.org/10.1016/j.chemosphere.2010.09.074

Mohamat-Yusuff, F., Sarah-Nabila, Ab.G., Zulkifli, S.Z., Azmai, M.N.A., Ibrahim, W.N.W., Yusof, S., Ismail, A., 2018. Acute toxicity test of copper pyrithione on Javanese medaka and the behavioural stress symptoms. Marine Pollution Bulletin 127, 150–153, https://doi.org/10.1016/j.marpolbul.2017.11.046

Shin, D., Y. Choi, Z. Y. Soon, M. Kim, D. J. Kim and J. H. Jung, 2022. Comparative toxicity study of waterborne two booster biocides (CuPT and ZnPT) on embryonic flounder (Paralichthys olivaceus). Ecotoxicology and Environmental Safety 233, https://doi.org/10.1016/j.ecoenv.2022.113337

Ponds, as small freshwater ecosystems, are particularly vulnerable due to their limited size. Yet they are often overlooked in research, possibly because they are considered less important (Biggs et al., 2017). Shallow water bodies support higher biodiversity than larger aquatic ecosystems. Peri-urban areas, characterized by a blend of agricultural and urban land uses, are dynamic and constantly evolving landscapes with diverse activities and stakeholders (Zoomers et al., 2017); as such, they are referred to as "restless landscapes" or zones of continual transformation (Zoomers et al., 2017). They often harbor neglected ecosystems, and despite their ecological importance, ponds and wetlands in peri-urban areas remain relatively underexplored (Wanek et al., 2021). Furthermore, these areas may experience increased contaminant inputs, which are regarded as one of the 12 major threats to freshwater biodiversity (Reid et al., 2019).

In this context, Hulot et al. (2025) monitored 12 peri-urban ponds in the Île-de-France region (near Paris, France) to investigate the relationships between land use, pollutant concentrations in water and sediment, and macroinvertebrate distribution. The originality of this work lies in its multidisciplinary and integrated approach, combining ecological and chemical analyses. While assessing agricultural, urban, grassland, and forest landscapes surrounding each pond, this study aimed to understand how contaminants constrain macroinvertebrate communities. The authors hypothesized that i) ponds in grassland and forest environments support higher local diversity than those in agricultural or urban areas, ii) rare and pollution-sensitive species significantly contribute to regional diversity, and iii) contaminants in water and sediment influence the distribution of macroinvertebrate morphotaxa.

This study provides numerous novel results. Specifically, it demonstrates that fluctuations in morphotaxa composition are predominantly driven by species replacement rather than by disparities in species richness. This pattern was largely attributed to the high prevalence of pollutant-tolerant species in certain ponds. In addition, community compositions appeared to be influenced by sediment levels of pharmaceuticals, water conductivity, and ammonium concentrations. In summary, ponds located in peri-urban areas are subject to a range of human-induced disturbances, and these results suggest that these disturbances lead to chronic and varied contamination, which in turn affects the composition of morphotaxa communities.

These findings establish a clear connection between local pollution and ecological composition, a crucial aspect for effective conservation and restoration efforts on peri-urban ponds.

References

Biggs, J., S. von Fumetti, Kelly-Quinn M. (2017). The importance of small waterbodies for biodiversity and ecosystem services: implications for policy makers. Hydrobiologia 793(1): 3-39 625. https://doi.org/10.1007/s10750-016-3007-0

Hulot, F.D., Hanot, C., Nélieu, S., Lamy, I., Karolak, S., Delarue, G., Baudry E., (2024) Do macroinvertebrate abundance and community structure depend on the quality of ponds located in peri-urban areas? ver.3 peer-reviewed and recommended by PCI Ecotoxicology and Environmental Chemistry. https://hal.science/hal-04850220v1

Reid, A. J., A. K. Carlson, I. F. Creed, E. J. Eliason, P. A. Gell, P. T. J. Johnson, 712 K. A. Kidd, T. J. MacCormack, J. D. Olden, S. J. Ormerod, J. P. Smol, W. W. Taylor, K. Tockner, J. C. Vermaire, D. Dudgeon, Cooke, S. J. 2019. Emerging threats and persistent conservation challenges for freshwater biodiversity. Biological Reviews 94(3):849-873. https://doi.org/10.1111/brv.12480

Wanek, A., C. L. M. Hargiss, J. Norland, Ellingson, N. 2021. Assessment of water quality in ponds across the rural, peri-urban, and urban gradient. Environmental Monitoring and Assessment 193: 694. https://doi.org/10.1007/s10661-021-09471-7

Zoomers, A., F. van Noorloos, K. Otsuki, G. Steel, van Westen, G. 2017. The Rush for Land in anUrbanizing World: From Land Grabbing Toward Developing Safe, Resilient, and Sustainable Cities and Landscapes. World Dev 92:242-252. https://doi.org/10.1016/j.worlddev.2016.11.016

The demand for lanthanides (LN) has seen a steady increase and is anticipated to continue to grow. Due to their unique properties, they have become essential in key components of new technologies, such as batteries, wind turbines, electronic components and other devices needed to facilitate energy transition away from fossil fuels. These elements are also increasingly used in a range of new technologies, including medical applications and telecommunication. In this context, the concentrations of lanthanides are expected to increase in freshwater environments (Gwenzi et al., 2018). Our limited knowledge about the risk that they pose to organisms limits our ability to develop guidelines for environmental protection. Research on this issue has so far been hindered by the peculiar properties of lanthanides, that tend to form insoluble precipitates when added in standard ecotoxicological test media (Blinova et al., 2018). This and other challenges of studying lanthanide toxicity were addressed in this in-depth study that leaves few stones unturned. 

The study by Vignati and colleagues (2024) is the first to investigate the acute toxicity of all LN, with the exception of promethium, a radioactive element, on Daphnia magna, a model test species, following the ISO 6341 (2012) norm. The authors designed their study to generate data useable for the development of risk assessment guidelines for the LN series and to generate data-based recommendations for future studies on LN ecotoxicity. They exposed daphnids to nine to ten dilutions of all tested LN in a medium and carried out 48-hour acute immobilization assays. Initial and final pH was measured along with concentrations of LN in the test solutions sampled at various intervals by ICP-MS. This data allowed calculation of LN speciation, performed using VisualMinteq software. Effect concentrations were also calculated using different metrics based on initial (nominal), time-averaged or modelled LN3+ exposure concentrations.

In their multi-faceted investigation, the authors reported several observations that clearly contribute to a better understanding of the ecotoxicity of LN to aquatic organisms and provide useful advice for future studies, briefly summarized here. Proper characterization of exposure concentrations is a key in any ecotoxicological study. Their project shows that even for a short, 48 h exposure, LN concentrations decrease due to a combination of precipitation and, possibly, adsorption. The concentration decrease was inversely proportional to the LN atomic mass, which may reduce the analytical requirements for future studies using the same test medium. The addition of LN to the test medium also modified pH and a detailed hypothesis is formulated to explain this phenomenon that has implications for ecotoxicological endpoints. Conclusions on LN ecotoxicity drawn in this study are based on experimental data and on extensive thermodynamic speciation modeling. The values of EC50 presented in the study varied by several order of magnitude depending on the chosen exposure metric, underscoring the urgent need for consensus-building on this issue across the research community. The authors also provide a comparison of their conclusions on EC50 values for daphnids with the limited data available in the literature, further validating their data with cautions carefully laid out about experimental design. The paper concludes with a list of seven caveats that should be considered both for regulators who will want to use the data presented in the paper for environmental LN concentrations regulations and for future studies. These caveats highlight the importance of considering LN speciation and chemical behavior during ecotoxicity assays, their influence on exposure concentrations, and their importance for risk assessment. They also reiterate that since LN concentrations in filtered water collected in the field are not directly comparable to EC50 values derived from laboratory studies using total or free LN3+ concentrations, an effort must be made to harmonize the methods of LN concentration measurements in field and laboratory studies. Overall, this paper may be one of the most rigorous studies in the current literature about LN ecotoxicity in freshwater systems. In its approach, it sets a precedent for future studies aiming at generating EC50 values or other toxicological endpoints of inorganic contaminants. The paper, carefully reviewed by Carrie Rickwood and by an anonymous reviewer, is a major contribution towards our understanding of LN ecotoxicity.
 
References
Blinova, I., Lukjanova, A., Muna, M., Vija, H., & Kahru, A. (2018). Evaluation of the potential hazard of lanthanides to freshwater microcrustaceans. Sci. Tot. Environ. 642 :1100-1107. https://doi.org/10.1016/j.scitotenv.2018.06.155

Gwenzi, W., Mangori, L.,  Danha, C., Chaukura, N, Dunjana, N., Sanganyado, E. (2018). Sources, behaviour, and environmental and human health risks of high technology rare earth elements as emerging contaminants. Sci. Total Environ., 636:299-313. https://doi.org/10.1016/j.scitotenv.2018.04.235

ISO. (2012). Water quality — Determination of the inhibition of the mobility of Daphnia magna Straus (Cladocera, Crustacea) — Acute toxicity test (norm 6341). https://www.iso.org/standard/54614.html

Vignati, D.A.L., Martin, L.A., Poirier, L., Zalouk-Vergnoux, A., Fouque, C., Clément, B., Hissler, C., Cossu-Leguille, C. (2024). Ecotoxicity of lanthanides to Daphnia magna: insights from elemental behavior and speciation in a standardized test medium. Ver.3 peer-reviewed and recommended by Peer Community In Ecotoxicology and Environmental Chemistry. https://hal.science/LIEC-UL/hal-04302491v3

Pesticides give rise to considerable concern due to their impact on biodiversity. Amongst the vast range of compounds used as herbicides, glyphosate (GLY) is the most widely applied one at global scale and its transformation product, aminomethylphosphonic acid (AMPA) is also ubiquitous. However, the toxicity of these chemicals on non-target organisms, including mammals, is somewhat overlooked (Kissane et al., 2017). Beside these two chemicals, Fritsch et al. (2024) also considered another organophosphorus herbicide, i.e. glufosinate (GLUF). Their study examined exposure levels in rodents and shrews living in contrasted cropped and semi-natural habitats in France – i.e., conventional farmland, organic fields, and hedgerows – through the analysis of herbicide residues in their hair. The hypothesis that herbicide residues in hair reflect the exposure to multiple pesticides in wildlife is supported by several papers (i.e. Krief et al. 2017; Fritsch et al. 2022).

Results obtained by Fritsch et al. (2024) indicated that the target compounds were widespread in the investigated environments, i.e. GLY, AMPA, and GLUF were detected in 64%, 51%, and 44% of samples, respectively. Diet appeared as a major driver of contamination, as herbivorous and omnivorous voles exhibited higher contamination levels than insectivorous or omnivorous species such as shrews and wild mice. In addition, habitat was also a significant factor: GLY concentrations were particularly high in individuals collected from hedgerows, surpassing those found in crop fields. This unexpected result highlights the contamination of areas considered as ecological refuges for the investigated species. Exposure levels did not show clear differences across sites, based on farming practices or pesticide application intensity.

In addition, the measured concentrations of GLY (median 2.7 pg/mg), AMPA (median 1.4 pg/mg), and GLUF (median 3.5 pg/mg) frequently reached thresholds associated with toxic effects on small mammals. In worst case scenarios, exceedance percentages attained values as high as 94 %.

Altogether, these results definitely raise concerns about the potential impact of GLY, AMPA and GLUF on non-target wildlife species and populations. These findings by Fritsch et al. (2024) therefore emphasize the widespread presence of these chemicals in agricultural landscapes and question the safety of herbicide use, even in habitats meant to protect biodiversity. This study underscores the need for more comprehensive evaluation of the ecological effects of herbicides to guide policy and conservation efforts.

References

Kissane Z, Shephard JM (2017) The rise of glyphosate and new opportunities for biosentinel early-1068 warning studies. Conservation Biology 31: 1293–1300; https://doi.org/10.1111/cobi.12955

Krief S, Berny P, Gumisiriza F, Gross R, Demeneix B, Fini JB, et al. (2017) Agricultural expansion as risk to endangered wildlife: Pesticide exposure in wild chimpanzees and baboons displaying facial dysplasia. Science of the Total Environment 598:647–656; 1072; https://doi.org/10.1016/j.scitotenv.2017.04.113

Fritsch C, Appenzeller BM, Burkart L, Coeurdassier M, Scheifler R, Raoul F, et al. (2022) Pervasive exposure 1041 of wild small mammals to legacy and currently used pesticide mixtures in arable landscapes. 1042 Sci Rep 12:15904; https://doi.org/10.1038/s41598-022-19959-y

Fritsch C, Appenzeller BM, Bertrand C, Coeurdassier M, Driget V, Hardy EM, Palazzi P, et al. (2024) Exposure of wild mammals to glyphosate, AMPA, and glufosinate: a case for “emerging organic contaminants”?. HAL, ver.3 peer-reviewed and recommended by PCI Ecotoxicology and Environmental Chemistry https://hal.science/hal-04485797

For many decades, the macrocyclic lactone drug ivermectin is extensively used in veterinary medicine and agriculture, as well as human medicine. Residues of ivermectin excreted in cattle dung remain persistent in soils (Mougin et al., 2003), biologically active and threaten non-target soil and coprophagous organisms such as dung flies and beetles (Lumaret et al., 2012). Ivermectin affects highly beneficial and taxonomically diverse groups inhabiting dung pats, including flies, parasitic wasps, as well as coprophilus and predatory dung beetles (Villar et al., 2022). Ivermectin resistance is well document in insects, but it seems to take longer and to be less effective than resistance to insecticides or other antiparasitic drugs, because of different physiological mechanisms involved in resistance (Seaman et al., 2015).

In that context, Gonzalez-Tokman et al. (2024) compared the reproductive success of a line of dung beetles (Euoniticellus intermedius, Scarabaeinae) exposed to a moderate concentration of invermectin during 18 generations, and a control line of beatles that was maintained free of antiparasitic drug. They carried-out toxicity experiments with increasing ivermectin concentrations to determine if sensitivity to ivermectin was reduced after some generations of exposure, possibly by acquiring resistance by means of transgenerational effects. Thus, dung beetles did not generate resistance to ivermectin after 18 generations of continuous exposure, and quantitative genetic analyses showed only low genetic variation in response to ivermectin.

The results published by Gonzalez-Tokman et al. (2024) indicated a low potential of beetles for adaptation to the drug, and suggest for non-target invertebrate groups a possible risk of extinction in ivermectin-contaminated pastures. These effects can greatly impact grassland ecology, lower their quality and reduce the area available and palatable to livestock.

References

Mougin, C., Kollmann, A., Dubroca, J., Ducrot, P.-H., Alvinerie, M., Galtier, P., 2003. Fate of the veterinary medicine ivermectin in soil. Environ. Chem. Letters 1, 131-134. https://doi.org/10.1007/s10311-003-0032-9

Lumaret, JP., Errouissi, F., Floate, K., Römbke, J., Wardhaugh, K., 2012. A review on the toxicity and non-target effects of macrocyclic lactones in terrestrial and aquatic environments. Current Pharmaceutical Biotechnology 13(6), 1004-60. https://doi.org/10.2174/138920112800399257

Villar, D., & Schaeffer, D.J., 2022. Ivermectin use on pastured livestock in Colombia: parasite resistance and impacts on the dung community. Revista Colombiana De Ciencias Pecuarias, 36(1), 3-12. https://doi.org/10.17533/udea.rccp.v36n1a2

Seaman, J.A., Alout, H., Meyers, J.I., Stenglein, M.D., Dabiré, R.K., Lozano-Fuentes, S., Burton, T.A., 471 Kuklinski, W.S., Black, W.C., Foy, B.D., 2015. Age and prior blood feeding of Anopheles gambiae influences their susceptibility and gene expression patterns to ivermectin-containing blood meals. BMC Genomics 16, 797. https://doi.org/10.1186/s12864-015-2029-8 

González-Tokman, D., Arellano-Torres, A., Baena-Díaz, F., Bustos, C., Martínez M., I., 2024. Ivermectin resistance in dung beetles exposed for multiple generations, bioRxiv ver. 3 peer-reviewed and recommended by Peer Community in Ecotoxicology and Environmental Chemistry. https://doi.org/10.1101/2023.05.08.539900