Ecotoxicological Studies Research Articles

Multi-omics provide mechanistic insight into the Pb-induced changes in tadpole fitness-related traits and environmental water quality

Water pollution from lead/Pb2+ poses a significant threat to aquatic ecosystems, and its repercussions on aquatic animals have received considerable attention. Although Pb2+ has been found to affect numerous aspects of animals, including individual fitness, metabolic status, and symbiotic microbiota, few studies have focused on the associations between Pb2+-induced variations in fitness, metabolome, symbiotic microbiome, and environmental parameters in the same system, limiting a comprehensive understanding of ecotoxicological mechanisms from a holistic perspective. Moreover, most ecotoxicological studies neglected the potential contributions of anions to the consequences generated by inorganic lead compounds. We investigated the effects of Pb(NO3)2 at environmentally relevant concentrations on the Rana omeimontis tadpoles and the water quality around them, using blank and NaNO3-treated groups as control. Results showed that Pb(NO3)2 not only induced a rise in water nitrite level, but exposure to this chemical also impaired tadpole fitness-related traits (e.g., growth and development). The impacts on tadpoles were most likely a combination of Pb2+ and NO3-. Tissue metabolomics revealed that Pb(NO3)2 exposure influenced animal substrate (i.e., carbohydrate, lipid, and amino acid) and prostaglandin metabolism. Pb(NO3)2 produced profound shifts in gut microbiota, with increased Proteobacteria impairing Firmicutes, resulting in higher aerobic and possibly pathogenic bacteria. NaNO3 also influenced tadpole metabolome and gut microbiome, in a manner different to that of Pb(NO3)2. The presence of NO3- seemed to counteract some changes caused by Pb2+, particularly on the microbiota. Piecewise structural equation model and correlation analyses demonstrated connections between tissue metabolome and gut microbiome, and the variations in tadpole phenotypic traits and water quality were linked to changes in tissue metabolome and gut microbiome. These findings emphasized the important roles of gut microbiome in mediating the effects of toxin on aquatic ecosystem. Moreover, it is suggested to consider the influences of anions in the risk assessment of heavy metal pollutions.

Gut microbiota impairment following graphene oxide exposure is associated to physiological alterations in Xenopus laevis tadpoles

Graphene-based nanomaterials such as graphene oxide (GO) possess unique properties triggering high expectations for the development of technological applications. Thus, GO is likely to be released in aquatic ecosystems. It is essential to evaluate its ecotoxicological potential to ensure a safe use of these nanomaterials. In amphibians, previous studies highlighted X. laevis tadpole growth inhibitions together with metabolic disturbances and genotoxic effects following GO exposure. As GO is known to exert bactericidal effects whereas the gut microbiota constitutes a compartment involved in host homeostasis regulation, it is important to determine if this microbial compartment constitutes a toxicological pathway involved in known GO-induced host physiological impairments. This study investigates the potential link between gut microbial communities and host physiological alterations. For this purpose, X. laevis tadpoles were exposed during 12 days to GO. Growth rate was monitored every 2 days and genotoxicity was assessed through enumeration of micronucleated erythrocytes. Genomic DNA was also extracted from the whole intestine to quantify gut bacteria and to analyze the community composition. GO exposure led to a dose dependent growth inhibition and genotoxic effects were detected following exposure to low doses. A transient decrease of the total bacteria was noticed with a persistent shift in the gut microbiota structure in exposed animals. Genotoxic effects were associated to gut microbiota remodeling characterized by an increase of the relative abundance of Bacteroides fragilis. The growth inhibitory effects would be associated to a shift in the Firmicutes/Bacteroidetes ratio while metagenome inference suggested changes in metabolic pathways and upregulation of detoxification processes. This work indicates that the gut microbiota compartment is a biological compartment of interest as it is integrative of host physiological alterations and should be considered for ecotoxicological studies as structural or functional impairments could lead to later life host fitness loss.

Activation of persulfate using copper oxide nanoparticles for the degradation of Rhodamine B containing effluents: Degradation efficiency and ecotoxicological studies

The development and implementation of advanced oxidation processes (AOP) are intended to assist in the treatment of effluents produced during anthropogenic activities, reducing the release of chemicals to the environment and consequently their potential toxicity to the environment. The present work is intended to assess the chemical and ecotoxicological efficiency of an AOP that uses copper oxide nanoparticles (CuO-NP) and persulfate (PS, as an oxidation agent) for the removal of Rhodamine B (RhB) from an aqueous solution. For this, CuO-NPs were prepared and used as a sole catalyst or combined with thermal treatment to activate PS for the degradation of RhB (in distilled water, DI, and in ASTM medium). Kinetic and mechanistic studies were employed to understand the performance of the system. The lethal ecotoxicity of the untreated and treated RhB solution was characterized using rotifer species Brachionus calyciflorus. Complete removal of RhB was achieved at [RhB]0 = 50 mg/L, [PS]0 = 1 mM, CuO = 0.5 g/L under pH = 7.5 at 45 °C for DI and ASTM. Brachionus calyciflorus mortality pointed to a very high ecotoxicity of the effluent before and after the AOP treatment; the former was less toxic than the latter: LC50,24h = 44.3% and 8.24%, respectively. Mortality observed in the treated effluent was most probably due to the presence of reaction products (e.g., activated PS) rather than RhB, since CuO/PS system was able to remove >90% of RhB. The obtained results demonstrated that although the proposed method is applicable to deal with high concentrations of recalcitrant organic compounds, the treated effluents can cause high ecotoxicity when released into the environment.

Effects of a Neonicotinoid Insecticide and Population Density on Behavior and Development of Wood Frogs (Rana sylvatica).

Amphibians have been facing global declines over the last decades from direct and indirect effects of anthropogenic activities. A contributor to declines is waterway contamination from agricultural runoffs of pesticides such as neonicotinoids. Beyond direct and indirect effects of the pesticide, few studies have investigated the possible interactions between neonicotinoids and natural environmental stressors across larval development, which could alter the strength and direction of observed neonicotinoid effects. The present study used a fully crossed design to investigate how a concentration of imidacloprid (a neonicotinoid; 10 µg/L) measured in surface waters interacted with low and high population densities (0.33 and 1 tadpole/L, respectively), an important environmental stressor, to influence behavior and development across metamorphosis in wood frogs (Rana sylvatica), known to breed in agricultural landscapes. Behaviors were measured in the absence and presence of predation cues using open-field tests at three distinct developmental stages, up to the metamorph stage. We found that imidacloprid did not interact with population density or independently affect behaviors in the absence of predation cues. However, individuals raised at high density compared with low density were more active at an early developmental stage but less active at metamorphic climax. Furthermore, both density and imidacloprid independently decreased the natural freezing response of tadpoles to predation cues. Finally, we found that distance traveled in the open-field test was weakly repeatable between aquatic stages but not repeatable across metamorphosis, a pattern that was not affected by treatments. The present study provides novel insights on the ecotoxicology of imidacloprid in the presence of a natural stressor, highlighting the importance of including behavioral assays and natural stressors in studies of amphibian ecotoxicology. Environ Toxicol Chem 2022;41:2968-2980. © 2022 SETAC.

Phenology of the transcriptome coincides with the physiology of double-crested cormorant embryonic development

The rigorous timing of the dynamic transcriptome within the embryo has to be well orchestrated for normal development. Identifying the phenology of the transcriptome along with the physiology of embryonic development in birds may suggest periods of increased sensitivity to contaminant exposure depending on the contaminant's mechanism of action. Double-crested cormorants (Nannopterum auritum, formerly Phalacrocorax auritus) are commonly used in ecotoxicological studies, but relatively little is known about their functional transcriptome profile in early development. In this study, we tracked the phenology of the transcriptome during N. auritum embryogenesis. Fresh eggs were collected from a reference site and artificially incubated from collection until four days prior to hatching. Embryos were periodically sampled throughout incubation for a total of seven time points. A custom microarray was designed for cormorants (over 14,000 probes) and used for transcriptome analysis in whole body (days 5, 8) and liver tissue (days 12, 14, 16, 20, 24). Three main developmental periods (early, mid, and late incubation) were identified with differentially expressed genes, gene sets, and pathways within and between each developmental transition. Overall, the timing of differentially expressed genes and enriched pathways corresponded to previously documented changes in morphology, neurology, or physiology during avian embryonic development. Targeted investigation of a subset of genes involved in endogenous and xenobiotic metabolism (e.g., cytochrome P450 cyp1a, cyp1b1, superoxide dismutase 1 sod1) were expressed in a pattern similar to reported endogenous compound levels. These data can provide insights on normal embryonic development in an ecologically relevant species without any environmental contaminant exposure.

Gone with sunscreens: Responses of blue mussels (Mytilus edulis) to a wide concentration range of a UV filter ensulizole

Organic UV filters have emerged as a new threat to marine organisms, but ecotoxicological studies have so far focused on only a few substances despite the chemical diversity of these synthetic sunscreen agents. Here we examined the responses of blue mussels Mytilus edulis to ensulizole, a non-lipophilic UV filter commonly found in the Baltic Sea. Mussels were exposed for three weeks to five ensulizole concentrations of 10, 102, 103, 104, and 105 ng/L. Stress on stress response was evaluated by subjecting mussels to air exposure. A battery of biomarkers related to detoxification and antioxidant defense, oxidative stress damage, energy reserves and metabolism, autophagy, apoptosis, inflammation, and DNA damage was measured in the gills and the digestive gland. In general, ensulizole affected the antioxidant response, energy storage, and cell death-related processes in mussel tissues. Mussels exposed to low, environmentally relevant concentrations of ensulizole had a shorter air survival time than the control. Ensulizole often showed the non-monotonic concentration-response curves, suggesting the complex effects of this UV filter at molecular, biochemical, and organismal levels.

Ecotoxicological studies of surface and groundwater in the adjacent territories of the Shuakhevi HPP (Adjara AR)

In the pathogenesis of autoimmune diseases, including immune thrombocytopenia (ITP), maintenance of inflammation and the loss of immune tolerance is essential. Transforming growth factor-beta (TGF-β) is a regulatory cytokine with pleiotropic function. TGF-β inhibits differentiation of T helper (Th1, Th2) cells and promotes the development of peripheral Tregs. The aim of our study was to explore the plasma levels of TGF-β and to perform its correlative analyses with peripheral blood biomarkers of systemic inflammation (NLR, PLR, PMR, SII, dNLR) in patients with ITP who did not respond to the first line treatment and had splenectomy as a second line therapy. The concentrations of TGF-β in plasma was quantified using ELISA kits by eBioscience. Statistical analyses was performed using Graph Pad Prism - Mann Whitney U test; for the correlation analyses we used spearman rank correlation by SPSS program. Our study revealed that the level of TGF-β in patients with refractory ITP is significantly diminished compared to the healthy subjects or patients undergoing splenectomy for other reasons than autoimmune or malignant hematological pathologies. There was no correlation observed between the plasma concentrations of TGF-β and the peripheral blood biomarkers of systemic inflammation.

Ecotoxicological studies of surface and groundwater in the adjacent territories of the Shuakhevi HPP (Adjara AR)

River Adjaristskhali gorge alongside territories are refugium for third moisture Kolkhetian relictic forest eco-systems which was given UNESCO world natural heritage status. At present construction and exploitation of cascade type derivative hydroelectric stations in the gorge creates risk for fragmentation, destroy and losing of natural habitats. Elemental analysis of underground spring water by plasma atomic-emission spectrometry was carried out at Shuakhevi township location.The obtained data were compared with the results of the multi-elemental analysis of the Achariskali River. The basic macro-elements in spring water and river Adjaristskhali are Ca and Mg. in samples of river Adjaristskhali concentrations of P, Fe, Al  are beyond MPC which is the verification for their anthropogenic pollutions. Besides such dangerous pollutants as Hg, Li, Pb, Ti is beyond MPC. Foreseeing the specificity, relief of Adjaristskhali it is necessary to carry serious geological and ecological examinations during construction and exploitation of Hydroelectric Stations, later  - carrying periodic monitoring in order to identify problem areas and carry proper preventive measures.   

The Comprehensive Health Risk Assessment of Polish Smelters with Ecotoxicological Studies.

Air pollution connected to smelter activity can significantly deteriorate the quality of soil due to the precipitation of rain or simple deposition of the air particulates into the ground. Hence, in this study, we focused on the analysis of the soil which can inform us about the general state of the environment in the area and the possible health hazard for humans. If the top layer of the soil is in bad condition, it can indicate that air pollution in the area is also not in good condition, and the lives of the inhabitants of these areas can be at serious risk. To comprehensively identify the level of contamination in the soils from the areas of Polish smelters, studies of the concentration of potentially toxic elements (PTEs) in the soil were conducted. On the basis of the obtained results, health risk assessment was performed to verify the possible influence on human health. The results showed that the non-carcinogenic risk existed only for Oława, while the possibility of the carcinogenic risk occurred in all of the studied places. The outcome is very disturbing and certain steps must be undertaken in order to protect the lives of the inhabitants. Additionally, in order to assess the suitability of soils for the cultivation of edible plants, phytotoxicity tests were conducted. The obtained results revealed that in all the studied areas, a visible inhibition of roots and shoots can be observed. The conducted study indicated the most polluted regions and the possible health hazard, and it can provide the general information about the impact of smelters on the environment.

Stress response to trace elements mixture of different embryo-larval stages of Paracentrotus lividus.

This study investigated for the first time the oxidative biomarkers responses in all larval stages of sea urchin. The contamination effects were reproduced by using contaminated seawater to concentrations measured in the area adjacent to an old asbestos mine at factors of 5 and 10. The results suggested that the concentrations were not sufficiently high to induce a major oxidative stress. The biometric differences make this method a more sensitive approach for assessing the effects on sea urchin larvae. Measurements of specific activities of antioxidant enzymes at each stage suggested a high capacity of the larvae to respond to oxidative stress. This normal activity of the organism must be considered in future research. This work also highlighted the importance of spawners provenance in ecotoxicological studies. These data are essential to better understand the stress responses of sea urchin larvae and provide baseline information for later environmental assessment research.

Ecotoxicological studies of surface and groundwater in the adjacent territories of the Shuakhevi HPP (Adjara AR)

In the pathogenesis of autoimmune diseases, including immune thrombocytopenia (ITP), maintenance of inflammation and the loss of immune tolerance is essential. Transforming growth factor-beta (TGF-β) is a regulatory cytokine with pleiotropic function. TGF-β inhibits differentiation of T helper (Th1, Th2) cells and promotes the development of peripheral Tregs. The aim of our study was to explore the plasma levels of TGF-β and to perform its correlative analyses with peripheral blood biomarkers of systemic inflammation (NLR, PLR, PMR, SII, dNLR) in patients with ITP who did not respond to the first line treatment and had splenectomy as a second line therapy. The concentrations of TGF-β in plasma was quantified using ELISA kits by eBioscience. Statistical analyses was performed using Graph Pad Prism - Mann Whitney U test; for the correlation analyses we used spearman rank correlation by SPSS program. Our study revealed that the level of TGF-β in patients with refractory ITP is significantly diminished compared to the healthy subjects or patients undergoing splenectomy for other reasons than autoimmune or malignant hematological pathologies. There was no correlation observed between the plasma concentrations of TGF-β and the peripheral blood biomarkers of systemic inflammation.

Concentrations and source identification of priority polycyclic aromatic hydrocarbons in sediment cores from south and northeast Thailand

In this study, the environmental fate of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in tropical lake sediments and their potential sources have been discussed. 15 PAHs (i.e. ΣPAH) have been investigated in two lakes, namely Songkhla Lake (SKL) and Nong Han Kumphawapi Lake (NHL), which are located at the southern and north-eastern parts of Thailand, respectively. Since these two lakes are registered as important wetlands under the Ramsar convention (United Nations Educational, Scientific and Cultural Organization: UNESCO), the quantitative identification of potential contributors of PAHs is an inevitable analytical tool for launching an evidence-based policy. The ΣPAH concentrations observed in SKL and NHL sediments (n = 135) were in the range of 19.4–1,218 ng g−1 and 94.5–1,112 ng g−1, respectively. While the exponential decline of ΣPAH contents were detected in SKL sediments, NHL showed a trend of enhancing PAH contents with depth. The averaged benzo [a]pyrene (B [a]P) contents of surface sediments in both lakes were much below the value stipulated by the United States Environmental Protection Agency (US-EPA) guidelines for carcinogen risk assessment. Based on numerous multivariate statistical techniques coupled with source apportionment analysis, “biomass burning” and “anthropogenic activities” are two potential contributors of the PAHs detected in the study areas. To achieve the long-term conservation of nature with related ecosystem services and cultural values, it is therefore important to promote decision-making based on ecotoxicological studies of carcinogenic substances.

Stygofaunal diversity and ecological sustainability of coastal groundwater ecosystems in a changing climate: The Australian paradigm

Abstract Coastal aquifers are vital water sources for humanity. Their quality and the ecosystem services they provide depend on the integrity of their subterranean biota. However, current anthropogenic impacts such as climate change effects and coastal population growth place enormous pressure on the sustainability of these environments. Despite the significance of subterranean biota to ecosystem function and the delivery of ecosystem services, stygofauna—groundwater‐dwelling aquatic animals—have until recently been largely ignored in aquifer monitoring and management. This issue is of importance in both coastal and inland zones. Common threats in inland and coastal areas are water extraction, reduced recharge caused by aridification, and pollution, while, in coastal zones, additional complications arise from sea‐level change and salt water ingress. This review examines stygofaunal diversity, impacts, and future conservation challenges in coastal aquifers. Focussing on Australia, we provide a summary of the available data on stygofaunal communities and distributions; identify and describe potential threats to these communities across the diverse coastal regions of the continent; and propose future research priorities with the goal of facilitating the long‐term preservation of these ecosystems on the Australian continent. While we focus this review on Australia, the threats and management issues discussed are relevant globally. Recent subterranean studies in Australia have been primarily undertaken in inland areas, and while coastal data exist, ecological assessment of coastal subterranean ecosystems is incomplete, compromising the efficacy of conservation plans. This review indicates that the Australian continent hosts five major coastal stygofaunal biodiversity areas characterised by heterogeneous community assemblages, involving a total of 17 taxonomic groups spanning microscopic aquatic invertebrates to vertebrates. The most relevant impacts and threats identified were aquifer size reduction, intrusion of seawater, land clearing, contamination, and mining. Given the projections of increasing coastal development and subsequent loss or degradation of habitat during coming decades, it is important to improve our limited understanding of the ecology of coastal aquifers. Future research should include the refinement of biological assessment tools for coastal systems, functional and ecotoxicological studies, and faunal surveys of urban coastal aquifers. The recommendations and guidelines outlined in this review are applicable globally and provide a further step toward the sustainable use of coastal groundwater resources and the maintenance of healthy groundwater ecosystems.

Studies on a widely-recognized snail model species (Lymnaea stagnalis) provide further evidence that vertebrate steroids do not have a hormonal role in the reproduction of mollusks.

Experiments were carried out to determine whether, as with other mollusks that have been studied, the snail, Lymnaea stagnalis, can absorb, esterify and store vertebrate steroids that are present in the water. We also carried out experiments to determine whether neural tissues of the snail could be immunohistochemically stained with an antibody to human aromatase (a key enzyme that catalyzes the conversion of testosterone [T] to 17β-estradiol [E2]); and, if so, to determine the significance of such staining. Previous studies on other mollusks have reported such staining and have proposed this as decisive evidence that mollusks have the same steroid synthesis pathway as vertebrates. We found that snails absorb, esterify and retain esterified T, E2, progesterone and ethinyl-estradiol (albeit with an absorption rate about four times slower, on a weight basis, than the mussel, Mytilus edulis). We also found that not only anti-human aromatase, but also anti-human nuclear progesterone receptor (nPR) and anti-human gonadotropin-releasing hormone antibodies immunohistochemically stained snail neural cells. However, further experiments, involving gel electrophoretic separation, followed by immunostaining, of proteins extracted from the neural tissue, found at least two positively-stained bands for each antibody, none of which had masses matching the human proteins to which the antibodies had been raised. The anti-aromatase antibody even stained the 140 kDA ladder protein used as a molecular weight marker on the gels. Mass spectrometric analysis of the bands did not find any peptide sequences that corresponded to the human proteins. Our findings confirm that the presence of vertebrate-like sex steroids in molluscan tissues is not necessarily evidence of endogenous origin. The results also show that immunohistochemical studies using antibodies against human proteins are grossly non-specific and likely to have little or no value in studying steroid synthesis or activity in mollusks. Our conclusions are consistent with the fact that genes for aromatase and nPR have not been found in the genome of the snail or of any other mollusk. Our overarching conclusion, from this and our previous studies, is that the endocrinology of mollusks is not the same as that of humans or any other vertebrates and that continuing to carry out physiological and ecotoxicological studies on mollusks on the basis of this false assumption, is an unconscionable waste of resources.

Comparison of oxidative stress biomarkers in Oreochromis mossambicus in minimally and highly disturbed aquatic environments in the Matabeleland region, Zimbabwe

Owing to their ability to provide a functional measure of organismal response to chemical stressors, oxidative biomarkers are useful in ecotoxicological studies to assess disturbance in aquatic environments. This study assessed the use of oxidative stress biomarkers in Oreochromis mossambicus (Peters, 1852) (Perciformes: Cichlidae) to distinguish between minimally and highly disturbed aquatic environments. A water quality index (WQI) and overall index of pollution (OIP) were used to characterize the target sites, namely the Mananda Dam (control, reference site) and Lower Mguza Dam (disturbed site). Forty male O. mossambicus samples were collected from each dam between April and August 2013. Values for the WQI and OIP indices were significantly higher for the Lower Mguza Dam than for the Mananda Dam (p < 0.05). Oxidative stress biomarker evaluation results showed that the activities of glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione S-transferase (GST) as well as the malondialdehyde (MDA) concentration in the liver of O. mossambicus were significantly higher in fish collected from Lower Mguza Dam than those collected from Mananda Dam (p < 0.05). The activities of DT-diaphorase (DTD) and catalase (CAT) were significantly inhibited in fish from the Lower Mguza Dam, when compared to those collected from the Mananda Dam (p < 0.05). From these findings, it is evident that oxidative stress biomarkers, such as antioxidant enzyme activity and MDA accumulation, can be used to differentiate minimally and highly disturbed aquatic environments.

Digital Video Acquisition and Optimization Techniques for Effective Animal Tracking in Behavioral Ecotoxicology.

Behavioral phenotypic analysis is an emerging and increasingly important toolbox in aquatic ecotoxicology. In this regard digital video recording has recently become a standard in obtaining behavioral data. Subsequent analysis requires applications of specialized software for detecting and reconstructing animal locomotory trajectories as well as extracting quantitative biometric endpoints associated with specific behavioral traits. Despite some profound advantages for behavioral ecotoxicology, there is a notable lack of standardization of procedures and guidelines that would aid in consistently acquiring high-quality digital videos. The latter are fundamental for using animal tracking software successfully and to avoid issues such as identification switching, incorrect interpolation, and low tracking visibility. Achieving an optimized tracking not only saves user time and effort to analyze the results but also provides high-fidelity data with minimal artifacts. In the present study we, for the first time, provide an easily accessible guide on how to set up and optimize digital video acquisition while minimizing pitfalls in obtaining the highest-quality data for subsequent animal tracking. We also discuss straightforward digital video postprocessing techniques that can be employed to further enhance tracking consistency or improve the videos that were acquired in otherwise suboptimal settings. The present study provides an essential guidebook for any aquatic ecotoxicology studies that utilize digital video acquisition systems for evaluation of behavioral endpoints. Environ Toxicol Chem 2022;41:2342-2352. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

High-quality genomes reveal significant genetic divergence and cryptic speciation in the model organism Folsomia candida (collembola).

The collembolan Folsomia candida Willem, 1902, is widely distributed throughout the world and has been frequently used as a test organism in soil ecology and ecotoxicology studies. However, it is questioned as an ideal "standard" because of differences in reproductive modes and cryptic genetic diversity between strains from various geographical origins. In this study, we obtained two high-quality chromosome-level genomes of F. candida, for a parthenogenetic strain (named FCDK, 219.08 Mb, 25,139 protein-coding genes) and a sexual strain (named FCSH, 153.09 Mb, 21,609 protein-coding genes), reannotated the genome of the parthenogenetic strain reported by Faddeeva-Vakhrusheva et al. in 2017 (named FCBL, 221.7Mb, 25,980 protein-coding genes) and conducted comparative genomic analyses of the three strains. High genome similarities between FCDK and FCBL based on synteny, genome architecture, mitochondrial and nuclear gene sequences suggest that they are conspecific. The seven chromosomes of FCDK are each 25%-54% larger than the corresponding chromosomes of FCSH, showing obvious repetitive element expansions and large-scale inversions and translocations but no whole-genome duplication. The strain-specific genes, expanded gene families and genes in nonsyntenic chromosomal regions identified in FCDK are highly related to the broader environmental adaptation of parthenogenetic strains. In addition, FCDK has fewer strain-specific microRNAs than FCSH, and their mitochondrial and nuclear genes have diverged greatly. In conclusion, FCDK/FCBL and FCSH have accumulated independent genetic changes and evolved into distinct species after 10 million years ago. Our work provides important genomic resources for studying the mechanisms of rapidly cryptic speciation and soil arthropod adaptation to soil ecosystems.

A recurring error in evaluating the effects of different pesticides, pollutants and fertilizers with a zero level

BackgroundThe Quenouille-Addelman solution has been proposed to properly analyze linear models with a crossed or factorial arrangement of treatments that includes a qualitative/categorical and a quantitative factor with a zero level, a situation particularly prevalent in ecotoxicological studies. However, a review of the recent literature reveals that this solution isn’t used, perhaps due to a lack of recognition that zero-level factors can produce incomplete factorial arrangements.ResultsUsing practical examples, I demonstrate that the conclusions of a study can be substantially altered if the Quenouille-Addelman solution is not used when warranted.ConclusionsSuspecting that the lack of a detailed method may have contributed to the underutilization of the solution, I describe how to apply the solution using current statistical software packages and discuss how the solution can be adapted to address some experimental situations not previously considered.

Acute toxicity of diuron and glyphosate in megalopae of Callinectes sapidus from the Jamapa River Estuary, Veracruz

The objective of this work was to evaluate the acute toxicity of the commercial herbicides Karmex® (diuron: DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea) and Herbipol® (glyphosate: N-(phosphonomethyl) glycine) on the megalopae of Callinectes sapidus and measure their relative abundance in the association of larval and postlarval species of crustaceans from the estuary of the Jamapa River, Veracruz. Collections were made overnight using white light traps. Likewise, dissolved oxygen, pH, temperature, total dissolved solids, and salinity were measured in situ. It was found that the association of larvae and postlarvae consisted of Macrobrachium acanthurus, M. olfersii, Potimirim mexicana, megalopae of C. sapidus and Armases ricordi, and zoeas of Brachyura. In total, 559 and 1057 C. sapidus megalopae were collected in November and March 2019, respectively. Dissolved oxygen was 6 and 7 mg L-1, pH was 7 and 8, the temperature was 26 and 27°C, total dissolved solids were 700 and 1500 ppm, and salinity was 0.70 and 16 in November and March, respectively. Using Probit analysis, a 96 h LC50 of diuron (Karmex®) was 7.69 ± 1.07 mg L-1 in March and 6.64 ± 0.93 mg L-1 in November. The LC50 for glyphosate (Herbipol®) was 247.83 ± 34.54 mg L-1 in March and 288.18 ± 38.66 3 mg L-1 in November. The blue crab C. sapidus is tolerant to a wide range of physicochemical factors; however, it is sensitive in the postlarval stages, like other species of crustaceans, to the herbicides diuron and glyphosate, for which the megalopae can be used in ecotoxicological studies.

A lentic microcosm approach to determine the toxicity of DDT and deltamethrin on diatom communities

Worldwide the use of pesticides has increased, especially in the industry and agriculture sector even though they contain highly toxic substances. The use of pesticides has various negative effects on the aquatic ecosystem and organisms within these ecosystems. The paper aimed to assess the effects of increased concentrations of malaria vector control insecticides (Dichlorodiphenyltrichloroethane (DDT) and Deltamethrin (DTM)) on the freshwater diatom community structure using a microcosm approach as well as determine whether a mixture (DDT 1:1 Deltamethrin) exposure will have a greater influence on the diatom community when compared to single exposures of these insecticides. Diatoms were exposed to a high and low concentration (based on LC50 data for freshwater Xenopus laevis from the USEPA Ecotox database) of DDT, DTM and a mixture in lentic microcosms over a total period of 28 days. Results indicated that irrespective of exposure concentrations, DDT, DTM and a mixture had negative effects on the diatom community including functionality and vitality as these insecticides induced changes to their chloroplasts. There was an increased percentage dead cells for all exposures compared to the control, with the insecticides having a phototoxic effect on the diatom community. Exposure to the selected insecticides caused a significant decrease in some diatom metrics indicating the negative effects these insecticides have on the diatom metrics. Therefore, diatoms may prove to be useful as bio-indicators in ecotoxicology studies when assessing the effects of any insecticide exposures.