An environmental oestrogen disrupts fish population dynamics through direct and transgenerational effects on survival and fecundity

Development of the integrated fish endocrine disruptor test (iFEDT)-Part A: Merging of existing fish test guidelines

There has been increasing interest in endocrine-disrupting chemicals (EDCs) among scientists and public authorities over the last 30 years, notably because of their wide use and the increasing evidence of detrimental effects on humans and the environment. However, test systems for the detection of potential EDCs as well as testing strategies still require optimization. Thus, the aim of the present project was the development of an integrated test protocol that merges the existing OECD test guidelines (TGs) 229 (fish short-term reproduction assay) and 234 (fish sexual development test) and implements thyroid-related endpoints for fish. The integrated fish endocrine disruptor test (iFEDT) represents a comprehensive approach for fish testing, which covers reproduction, early development, and sexual differentiation, and will thus allow the identification of multiple endocrine-disruptive effects in fish. Using zebrafish (Danio rerio) as a model organism, two exposure tests were performed with well-studied EDCs: 6-propyl-2-thiouracil (PTU), an inhibitor of thyroid hormone synthesis, and 17α-ethinylestradiol (EE2), an estrogen receptor agonist. In part A of this article, the effects of PTU and EE2 on established endpoints of the two existing TGs are reported, whereas part B focuses on the novel thyroid-related endpoints. Results of part A document that, as expected, both PTU and EE2 had strong effects on various endocrine-related endpoints in zebrafish and their offspring. Merging of TGs 229 and 234 proved feasible, and all established biomarkers and endpoints were responsive as expected, including reproductive and morphometric changes (PTU and EE2), vitellogenin levels, sex ratio, gonad maturation, and histopathology (only for EE2) of different life stages. A validation of the iFEDT with other well-known EDCs will allow verification of the sensitivity and usability and confirm its capacity to improve the existing testing strategy for EDCs in fish. Integr Environ Assess Manag 2024;20:817-829. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Multi-omic responses of fish exposed to complex chemical mixtures in the Shenandoah River watershed

To evaluate relationships between different anthropogenic impacts, contaminant occurrence, and fish health, we conducted in situ fish exposures across the Shenandoah River watershed at five sites with different land use. Exposure water was analyzed for over 500 chemical constituents, and organismal, metabolomic, and transcriptomic endpoints were measured in fathead minnows. Adverse reproductive outcomes were observed in fish exposed in the upper watershed at both wastewater treatment plant (WWTP) effluent- and agriculture-impacted sites, including decreased gonadosomatic index and altered secondary sex characteristics. This was accompanied with increased mortality at the site most impacted by agricultural activities. Molecular biomarkers of estrogen exposure were unchanged and consistent with low or non-detectable concentrations of common estrogens, indicating that alternative mechanisms were involved in organismal adverse outcomes. Hepatic metabolomic and transcriptomic profiles were altered in a site-specific manner, consistent with variation in land use and contaminant profiles. Integrated biomarker response data were useful for evaluating mechanistic linkages between contaminants and adverse outcomes, suggesting that reproductive endocrine disruption, altered lipid processes, and immunosuppression may have been involved in these organismal impacts. This study demonstrated linkages between human-impact, contaminant occurrence, and exposure effects in the Shenandoah River watershed and showed increased risk of adverse outcomes in fathead minnows exposed to complex mixtures at sites impacted by municipal wastewater discharges and agricultural practices.

Multigenerational impacts of EE2 on reproductive fitness and immune competence of marine medaka

Estrogenic endocrine disrupting chemicals (EEDC) have been suspected to impact offspring in a transgenerational manner via modifications of the germline epigenome in the directly exposed generations. A holistic assessment of the concentration/ exposure duration-response, threshold level, and critical exposure windows (parental gametogenesis and embryogenesis) for the transgenerational evaluation of reproduction and immune compromise concomitantly will inform the overall EEDC exposure risk. We conducted a multigenerational study using the environmental estrogen, 17α-ethinylestradiol (EE2), and the marine laboratory model fish Oryzias melastigma (adult, F0) and their offspring (F1-F4) to identify transgenerationally altered offspring generations and phenotype persistence. Three exposure scenarios were used: short parental exposure, long parental exposure, and a combined parental and embryonic exposure using two concentrations of EE2 (33ng/L, 113ng/L). The reproductive fitness of fish was evaluated by assessing fecundity, fertilization rate, hatching success, and sex ratio. Immune competence was assessed in adults via a host-resistance assay. EE2 exposure during both parental gametogenesis and embryogenesis was found to induce concentration/ exposure duration-dependent transgenerational reproductive effects in the unexposed F4 offspring. Furthermore, embryonic exposure to 113 ng/L EE2 induced feminization of the directly exposed F1 generation, followed by subsequent masculinization of the F2 and F3 generations. A sex difference was found in the transgenerationally impaired reproductive output with F4 females being sensitive to the lowest concentration of EE2 (33 ng/L) upon long-term ancestral parent exposure (21 days). Conversely, F4 males were affected by ancestral embryonic EE2 exposure. No definitive transgenerational impacts on immune competence were identified in male or female offspring. In combination, these results indicate that EEDCs can be transgenerational toxicants that may negatively impact the reproductive success and population sustainability of fish populations.

Effects of 17α-ethinylestradiol on the neuroendocrine gonadotropic system and behavior of European sea bass larvae (Dicentrarchus labrax)

The widespread use of 17α-ethinylestradiol (EE2), and other estrogenic endocrine disruptors, results in a continuous release of estrogenic compounds into aquatic environments. Xenoestrogens may interfere with the neuroendocrine system of aquatic organisms and may produce various adverse effects. The aim of the present study was to expose European sea bass larvae (Dicentrarchus labrax) to EE2 (0.5 and 50 nM) for 8 d and determine the expression levels of brain aromatase (cyp19a1b), gonadotropin-releasing hormones (gnrh1, gnrh2, gnrh3), kisspeptins (kiss1, kiss2) and estrogen receptors (esr1, esr2a, esr2b, gpera, gperb). Growth and behavior of larvae as evidenced by locomotor activity and anxiety-like behaviors were measured 8 d after EE2 treatment and a depuration period of 20 d. Exposure to 0.5 nM EE2 induced a significant increase in cyp19a1b expression levels, while upregulation of gnrh2, kiss1, and cyp19a1b expression was noted after 8 d at 50 nM EE2. Standard length at the end of the exposure phase was significantly lower in larvae exposed to 50 nM EE2 than in control; however, this effect was no longer observed after the depuration phase. The upregulation of gnrh2, kiss1, and cyp19a1b expression levels was found in conjunction with elevation in locomotor activity and anxiety-like behaviors in larvae. Behavioral alterations were still detected at the end of the depuration phase. Evidence indicates that the long-lasting effects of EE2 on behavior might impact normal development and subsequent fitness of exposed fish.

Accounting for transgenerational effects of toxicant exposure in population models alters the predicted long-term population status

Acute environmental stressors such as short-term exposure to pollutants can have lasting effects on organisms, potentially impacting future generations. Parental exposure to toxicants can result in changes to the epigenome (e.g., DNA methylation) that are passed down to subsequent, unexposed generations. However, it is difficult to gauge the cumulative population-scale impacts of epigenetic effects from laboratory experiments alone. Here, we developed a size- and age-structured delay-coordinate population model to evaluate the long-term consequences of epigenetic modifications on population sustainability. The model emulated changes in growth, mortality, and fecundity in the F0, F1, and F2 generations observed in experiments in which larval Menidia beryllina were exposed to environmentally relevant concentrations of bifenthrin (Bif), ethinylestradiol (EE2), levonorgestrel (LV), or trenbolone (TB) in the parent generation (F0) and reared in clean water up to the F2 generation. Our analysis suggests potentially dramatic population-level effects of repeated, chronic exposures of early-life stage fish that are not captured by models not accounting for those effects. Simulated exposures led to substantial declines in population abundance (LV and Bif) or near-extinction (EE2 and TB) with the exact trajectory and timeline of population decline dependent on the combination of F0, F1, and F2 effects produced by each compound. Even acute one-time exposures of each compound led to declines and recovery over multiple years due to lagged epigenetic effects. These results demonstrate the potential for environmentally relevant concentrations of commonly used compounds to impact the population dynamics and sustainability of an ecologically relevant species and model organism.

Seasonal variation in oestrogenic potency and biological effects of wastewater treatment works effluents assessed using ERE-GFP transgenic zebrafish embryo-larvae

Effluents from wastewater treatment works (WwTW) exhibit both temporal and spatial variation in oestrogenicity, however few studies have attempted to quantify how this variation affects biological responses in fish. Here we used an oestrogen-responsive green fluorescent protein (ERE-GFP) transgenic zebrafish (Danio rerio) to quantify oestrogenic activity and health effects for exposure to three different WwTW effluents. Endpoints measured included survival/hatching rate, GFP induction (measured in target tissues or gfp mRNA induction in whole embryos) and vtg mRNA induction in whole embryos. Exposure to one of the study effluents (at 100%), resulted in some mortality, and exposure to all three effluents (at 50% and 100%) caused decreases in hatching rates. Higher levels of vtg mRNA corresponded with higher levels of steroidal oestrogens in the different effluents, with lowest-observed-effect concentrations (LOECs) between 31 ng/L and 39 ng/L oestradiol equivalents (EEQs). Tissue patterns of GFP expression for all three WwTWs effluents reflected the known targets for steroidal oestrogens and for some other oestrogenic chemicals likely present in those effluents (i.e. nonylphenol or bisphenolic compounds). GFP induction was similarly responsive to vtg mRNA induction (a well-established biomarker for oestrogen exposure). We thus demonstrate the ERE-GFP transgenic zebrafish as an effective model for monitoring the oestrogenic potency and health effects for exposure to complex mixtures of chemicals contained within WwTW effluents.

Identification of active and inactive agonists/antagonists of estrogen receptor based on Tox21 10K compound library: Binomial analysis and structure alert

Endocrine disrupting chemicals can mimic, block, or interfere with hormones in organisms and subsequently affect their development and reproduction, which has raised significant public concern over the past several decades. To investigate (quantitative) structure-activity relationship, 8280 compounds were compiled from the Tox21 10K compound library. The results show that 50% activity concentrations of agonists are poorly related to that of antagonists because many compounds have considerably different activity concentrations between the agonists and antagonists. Analysis on the chemical classes based on mode of action (MOA) reveals that estrogen receptor (ER) is not the main target site in the acute toxicity to aquatic organisms. Binomial analysis of active and inactive ER agonists/antagonists reveals that ER activity of compounds is dominated by octanol/water partition coefficient and excess molar refraction. The binomial equation developed from the two descriptors can classify well active and inactive ER chemicals with an overall prediction accuracy of 73%. The classification equation developed from the molecular descriptors indicates that estrogens react with the receptor through hydrophobic and π-n electron interactions. At the same time, molecular ionization, polarity, and hydrogen bonding ability can also affect the chemical ER activity. A decision tree developed from chemical structures and their applications reveals that many hormones, proton pump inhibitors, PAHs, progestin, insecticides, fungicides, steroid and chemotherapy medications are active ER agonists/antagonists. On the other hand, many monocyclic/nonaromatic chain compounds and herbicides are inactive ER compounds. The decision tree and binomial equation developed here are valuable tools to predict active and inactive ER compounds.

Health Effects and Life Stage Sensitivities in Zebrafish Exposed to an Estrogenic Wastewater Treatment Works Effluent

A wide range of health effects in fish have been reported for exposure to wastewater treatment work (WwTW) effluents including feminized responses in males. Most of these exposure studies, however, have assessed acute health effects and chronic exposure effects are less well established. Using an Estrogen Responsive Element-Green Fluorescent Protein (ERE-GFP)-Casper transgenic zebrafish, we investigated chronic health effects and life stage sensitivities for exposure to an estrogenic WwTW effluent and the synthetic estrogen 17α-ethinylestradiol (EE2). Exposure to the WwTW effluent (at full strength;100%) and to 10 ng/L (nominal) EE2 delayed testis maturation in male fish but accelerated ovary development in females. Exposure to 50% and 100% effluent, and to 10 ng/L EE2, also resulted in skewed sex ratios in favor of females. Differing patterns of green fluorescent protein (GFP) expression, in terms of target tissues and developmental life stages occurred in the ERE-GFP- zebrafish chronically exposed to 100% effluent and reflected the estrogenic content of the effluent. gfp and vitellogenin (vtg) mRNA induction were positively correlated with measured levels of steroidal estrogens in the effluent throughout the study. Our findings illustrate the importance of a fish's developmental stage for estrogen exposure effects and demonstrate the utility of the ERE-GFP zebrafish for integrative health analysis for exposure to estrogenic chemical mixtures.

Parental exposure to polystyrene microplastics at environmentally relevant concentrations has negligible transgenerational effects on zebrafish (Danio rerio)

Waterborne exposure to highly persistent microplastic pollutants is a major concern for aquatic species worldwide. There are still gaps in knowledge on microplastics' potential transgenerational effects on offspring generation. Using zebrafish, this study investigated the survival and early development of offspring through a 21-day continuous parental treatment with polystyrene microplastics. The results showed that continuous waterborne exposure to high concentrations (>100 μg/L) of polystyrene microplastics (1 μm) for 21 days resulted in notable microplastic accumulation in adult fish intestines. Exposure at microplastic concentrations greater than 100 μg/L also induced significant changes in steroidogenic mRNA expression in zebrafish gonads. However, no significant changes in the cumulative number of eggs spawned and fertilization rate were observed at any parental exposure concentrations when compared to the control. Early development of derived offspring, in terms of hatching rate, body length, malformation rate and mortality rate, did not significantly differ from that of the control. This study showed that transgenerational effects of parental exposure to polystyrene microplastics in zebrafish might be negligible or recoverable. This study provided new results and insights on the transgenerational effects of microplastics on a freshwater fish species and can help to understand impacts of microplastics on freshwater ecosystems.

17α-ethynylestradiol prevents the natural male-to-female sex change in gilthead seabream (Sparus aurata L.)

Exposure to 17α-ethynylestradiol (EE2, 5 μg/g food) impairs some reproductive events in the protandrous gilthead seabream and a short recovery period does not allow full recovery. In this study, spermiating seabream males in the second reproductive cycle (RC) were fed a diet containing 5 or 2.5 μg EE2/g food for 28 days and then a commercial diet without EE2 for the remaining RC. Individuals were sampled at the end of the EE2 treatment and then at the end of the RC and at the beginning of the third RC, 146 and 333 days after the cessation of treatment, respectively. Increased hepatic transcript levels of the gene coding for vitellogenin (vtg) and plasma levels of Vtg indicated both concentrations of EE2 caused endocrine disruption. Modifications in the histological organization of the testis, germ cell proliferation, plasma levels of the sex steroids and pituitary expression levels of the genes coding for the gonadotropin β-subunits, fshβ and lhβ were detected. The plasma levels of Vtg and most of the reproductive parameters were restored 146 days after treatments. However, although 50% of the control fish underwent sex reversal as expected at the third RC, male-to female sex change was prevented by both EE2 concentrations.

Multigenerational and Transgenerational Effects of Environmentally Relevant Concentrations of Endocrine Disruptors in an Estuarine Fish Model

Many pollutants cause endocrine disruption in aquatic organisms. While studies of the direct effects of toxicants on exposed organisms are commonplace, little is known about the potential for toxicant exposures in a parental (F0) generation to affect unexposed F1 or F2 generations (multigenerational and transgenerational effects, respectively), particularly in estuarine fishes. To investigate this possibility, we exposed inland silversides (Menidia beryllina) to environmentally relevant (low ng/L) concentrations of ethinylestradiol, bifenthrin, trenbolone, and levonorgestrel from 8 hpf to 21 dph. We then measured development, immune response, reproduction, gene expression, and DNA methylation for two subsequent generations following the exposure. Larval exposure (F0) to each compound resulted in negative effects in the F0 and F1 generations, and for ethinylestradiol and levonorgestrel, the F2 also. The specific endpoints that were responsive to exposure in each generation varied, but included increased incidence of larval deformities, reduced larval growth and survival, impaired immune function, skewed sex ratios, ovarian atresia, reduced egg production, and altered gene expression. Additionally, exposed fish exhibited differences in DNA methylation in selected genes, across all three generations, indicating epigenetic transfer of effects. These findings suggest that assessments across multiple generations are key to determining the full magnitude of adverse effects from contaminant exposure in early life.

Transcriptome analysis of testis reveals the effects of developmental exposure to bisphenol a or 17α-ethinylestradiol in medaka (Oryzias latipes)

Endocrine disrupting chemicals (EDCs) can induce abnormalities in organisms via alteration of molecular pathways and subsequent disruption of endocrine functions. Bisphenol A (BPA) and 17α-ethinylestradiol (EE2) are ubiquitous EDCs in the environment. Many aquatic organisms, including fish, are often exposed to varying concentrations of BPA and EE2 throughout their lifespan. Both BPA and EE2 can activate estrogenic signaling pathways and cause adverse effects on reproduction via alteration of pathways associated with steroidogenesis. However, transcriptional pathways that are affected by chronic exposure to these two ubiquitous environmental estrogens during embryonic, larval, and juvenile stages are not clearly understood. In the present study, we examined transcriptional alterations in the testis of medaka fish (Oryzias latipes) chronically exposed to a low concentration of BPA or EE2. Medaka were exposed to BPA (10 μg/L) or EE2 (0.01 μg/L) from 8 h post-fertilization (as embryos) to adulthood 50 days post fertilization (dpf), and transcriptional alterations in the testis were examined by RNA sequencing (RNA-seq). Transcriptomic profiling revealed 651 differentially expressed genes (DEGs) between BPA-exposed and control testes, while 1475 DEGs were found between EE2-exposed and control testes. Gene ontology (GO) analysis showed a significant enrichment of "intracellular receptor signaling pathway", "response to steroid hormone" and "hormone-mediated signaling pathway" in the BPA-induced DEGs, and of "cilium organization", "microtubule-based process" and "organelle assembly" in the EE2-induced DEGs. Pathway analysis showed significant enrichment of "integrin signaling pathway" in both treatment groups, and of "cadherin signaling pathway", "Alzheimer disease-presenilin pathway" in EE2-induced DEGs. Single nucleotide polymorphism (SNP) and insertion-deletion (Indel) analysis found no significant differences in mutation rates with either BPA or EE2 treatments. Taken together, global gene expression differences in testes of medaka during early stages of gametogenesis were responsive to chronic BPA and EE2 exposure.

Exposure of zebrafish to elevated temperature induces sex ratio shifts and alterations in the testicular epigenome of unexposed offspring

Accumulating evidence shows that environmental changes can affect population sex ratios through epigenetic regulation of gene expression in species where sex depends on both genetic and environmental cues. Sometimes, altered sex ratios persist in the next generation even when the environmental cue is no longer present (a multigenerational effect). However, evidence of transgenerational effects (i.e., beyond the first non-exposed generation), which tend to be paternally transmitted, is scarce and a matter of debate. Here, we used the AB strain of zebrafish, where sex depends on both genetic and environmental influences, to study possible multi- (to the F₁) and transgenerational (to the F₂) effects of elevated temperature during the critical period of sex differentiation. From eight initial different families, five were selected in order to capture sufficient variation between the sex ratio of the control group (28 °C) and the group exposed to elevated (35 °C) temperature only at the parental (P) generation. Results showed a consistent increase in the proportion of males in the P generation in all five families as a result of heat treatment. Sex ratios were then determined in the F₁ and F₂ offspring derived from both above groups, which were all raised at 28 °C. A persisting male-skewed sex ratio in the 35°C-derived, unexposed offspring of the F₁ generation was observed in three families, denoting family-dependent multigenerational effects. However, no transgenerational effects were observed in the F₂ generation of any family. DNA methylation was also assessed in the testis of P, F₁ and F₂ males derived from exposed and non-exposed fathers and grandfathers. DNA methylation was significantly decreased only in the testis of the 35°C-derived males in the F₁ generation but not of the F₂ generation and, surprisingly, neither in the 35°C-exposed males of the P generation. Taken together, our results show great interfamily variation, not only in sex ratio response to elevated temperature, but also on its multigenerational effects, denoting a strong influence of genetics. Alterations in the testicular epigenome in F₁ males calls for attention to possible, previously unnoticed, effects of temperature in the unexposed offspring of heat-exposed parents in a global warming scenario.

Environmental estrogens and progestins disturb testis and brood pouch development with modifying transcriptomes in male-pregnancy lined seahorse Hippocampus erectus

Exposure to environmental estrogens and progestins has contributed to adverse effects on the reproduction of many aquatic wildlife species. However, few reports have paid attention to fish species with specialized reproductive strategies, such as male-pregnancy seahorses. In this study, the potential effects on the behavior, gonad and brood pouch development, and transcriptomic profiles of lined seahorse Hippocampus erectus exposed to environmentally relevant concentrations of 17α-ethynyl estradiol (EE2, 5 ng/L, 50 ng/L, 10 ng/L, 100 ng/L) or progesterone (P4) for 60 days were examined. Both EE2 and P4 significantly inhibited male brood pouch development by disrupting the extracellular matrix and basement membrane pathways. In addition, both EE2 and P4 impaired the expression of genes associated with spermatogenesis in the testis, and even caused male feminization. We suggest that seahorses be regarded as a sensitive indicator for evaluating the potential effects of endocrine disrupting chemical (EDC) pollution on aquatic biotic communities.

Experimental Approaches for Characterizing the Endocrine-Disrupting Effects of Environmental Chemicals in Fish

Increasing industrial and agricultural activities have led to a disturbing increase of pollutant discharges into the environment. Most of these pollutants can induce short-term, sustained or delayed impacts on developmental, physiological, and behavioral processes that are often regulated by the endocrine system in vertebrates, including fish, thus they are termed endocrine-disrupting chemicals (EDCs). Physiological impacts resulting from the exposure of these vertebrates to EDCs include abnormalities in growth and reproductive development, as many of the prevalent chemicals are capable of binding the receptors to sex steroid hormones. The approaches employed to investigate the action and impact of EDCs is largely dependent on the specific life history and habitat of each species, and the type of chemical that organisms are exposed to. Aquatic vertebrates, such as fish, are among the first organisms to be affected by waterborne EDCs, an attribute that has justified their wide-spread use as sentinel species. Many fish species are exposed to these chemicals in the wild, for either short or prolonged periods as larvae, adults, or both, thus, studies are typically designed to focus on either acute or chronic exposure at distinct developmental stages. The aim of this review is to provide an overview of the approaches and experimental methods commonly used to characterize the effects of some of the environmentally prevalent and emerging EDCs, including 17 α-ethinylestradiol, nonylphenol, BPA, phthalates, and arsenic; and the pervasive and potential carriers of EDCs, microplastics, on reproduction and growth. In vivo and in vitro studies are designed and employed to elucidate the direct effects of EDCs at the organismal and cellular levels, respectively. In silico approaches, on the other hand, comprise computational methods that have been more recently applied with the potential to replace extensive in vitro screening of EDCs. These approaches are discussed in light of model species, age and duration of EDC exposure.

Current evidence for a role of epigenetic mechanisms in response to ionizing radiation in an ecotoxicological context

The issue of potential long-term or hereditary effects for both humans and wildlife exposed to low doses (or dose rates) of ionising radiation is a major concern. Chronic exposure to ionising radiation, defined as an exposure over a large fraction of the organism's lifespan or even over several generations, can possibly have consequences in the progeny. Recent work has begun to show that epigenetics plays an important role in adaptation of organisms challenged to environmental stimulae. Changes to so-called epigenetic marks such as histone modifications, DNA methylation and non-coding RNAs result in altered transcriptomes and proteomes, without directly changing the DNA sequence. Moreover, some of these environmentally-induced epigenetic changes tend to persist over generations, and thus, epigenetic modifications are regarded as the conduits for environmental influence on the genome. Here, we review the current knowledge of possible involvement of epigenetics in the cascade of responses resulting from environmental exposure to ionising radiation. In addition, from a comparison of lab and field obtained data, we investigate evidence on radiation-induced changes in the epigenome and in particular the total or locus specific levels of DNA methylation. The challenges for future research and possible use of changes as an early warning (biomarker) of radiosensitivity and individual exposure is discussed. Such a biomarker could be used to detect and better understand the mechanisms of toxic action and inter/intra-species susceptibility to radiation within an environmental risk assessment and management context.

Impact of Long-Term Exposure to 17α-Ethinylestradiol in the Live-Bearing Fish Heterandria formosa

17α-ethinylestradiol (EE2) is a potent synthetic estrogen that is routinely detected in aquatic ecosystems and exhibits estrogenic activity. Acute and chronic toxicity have been described for oviparous and ovoviviparous fish species; however, no information is available on the impacts of EE2 on viviparous, matrotrophic fish despite their ecological importance. The present study investigated the consequences of long-term EE2 exposure in the least killifish (Heterandria formosa). Effects on growth, time-to-sexual maturity, fecundity, and offspring survival were examined in an 8-month, life-cycle experiment. Starting as 0-6-day-old fish, least killifish were continuously exposed to EE2 at nominal concentrations of 0, 5, or 25 ng/L (measured concentrations averaged 0, 4.3, and 21.5 ng/L respectively). In the F0 generation, EE2-exposure did not affect survival but resulted in increased time-to-sexual maturity and a sex-dependent effect on size; female standard length was reduced while male standard length was increased. This caused the ordinarily larger females and smaller males to become more similar in size. Condition factor was reduced for both sexes. Fecundity was reduced by 50% and 75% at 5 and 25 ng/L EE2-exposure respectively. Continued EE2-exposure in the F1 generation resulted in significantly reduced survival. These results suggest that despite their matrotrophic development, these fish experience delayed development and reduced reproductive success from EE2-exposure and that effects appear to intensify in the second generation.

Direct and indirect parental exposure to endocrine disruptors and elevated temperature influences gene expression across generations in a euryhaline model fish

Aquatic organisms inhabiting polluted waterways face numerous adverse effects, including physiological disruption by endocrine disrupting compounds (EDCs). Little is known about how the temperatures associated with global climate change may influence the response of organisms exposed to EDCs, and the effects that these combined stressors may have on molecular endpoints such as gene expression. We exposed Menidia beryllina (inland silversides) to environmentally relevant concentrations (1 ng/L) of two estrogenic EDCs (bifenthrin and 17α-ethinylestradiol; EE2) at 22 °C and 28 °C. We conducted this experiment over multiple generations to better understand the potential effects to chronically exposed populations in the wild. We exposed adult parental fish (F0) for 14 days prior to spawning of the next generation. F1 larvae were then exposed from fertilization until 21 days post hatch (dph) before being transferred to clean water tanks. F1 larvae were reared to adulthood, then spawned in clean water to test for further effects of parental exposure on offspring (F2 generation). Gene expression was quantified by performing qPCR on F0 and F1 gonads, as well as F1 and F2 larvae. We did not detect any significant differences in the expression of genes measured in the parental or F1 adult gonads. We found that the 28 °C EE2 treatment significantly decreased the expression of nearly all genes measured in the F1 larvae. This pattern was transferred to the F2 generation for expression of the follicle-stimulating hormone receptor (FSHR) gene. Expression of 17β-hydroxysteroid dehydrogenase (17β-HSD) and G protein-coupled receptor 30 (GPR30) revealed changes not measured in the previous generation. Effects of the bifenthrin treatments were not observed until the F2 generation, which were exposed to the chemicals indirectly as germ cells. Our results indicate that effects of EDCs and their interactions with abiotic factors, may not be adequately represented by singular generation testing. These findings will contribute to the determination of the risk of EDC contamination to organisms inhabiting contaminated waterways under changing temperature regimes.

Critical review: Grand challenges in assessing the adverse effects of contaminants of emerging concern on aquatic food webs

Much progress has been made in the past few decades in understanding the sources, transport, fate, and biological effects of contaminants of emerging concern (CECs) in aquatic ecosystems. Despite these advancements, significant obstacles still prevent comprehensive assessments of the environmental risks associated with the presence of CECs. Many of these obstacles center around the extrapolation of effects of single chemicals observed in the laboratory or effects found in individual organisms or species in the field to impacts of multiple stressors on aquatic food webs. In the present review, we identify 5 challenges that must be addressed to promote studies of CECs from singular exposure events to multispecies aquatic food web interactions. There needs to be: 1) more detailed information on the complexity of mixtures of CECs in the aquatic environment, 2) a greater understanding of the sublethal effects of CECs on a wide range of aquatic organisms, 3) an ascertaining of the biological consequences of variable duration CEC exposures within and across generations in aquatic species, 4) a linkage of multiple stressors with CEC exposure in aquatic systems, and 5) a documenting of the trophic consequences of CEC exposure across aquatic food webs. We examine the current literature to show how these challenges can be addressed to fill knowledge gaps. Environ Toxicol Chem 2019;38:46-60. © 2018 SETAC.

Application of BiOX Photocatalysts in Remediation of Persistent Organic Pollutants

Bismuth oxyhalides have recently gained attention for their promise as photocatalysts. Due to their layered structure, these materials present fascinating and highly desirable physicochemical properties including visible light photocatalytic capability and improved charge separation. While bismuth oxyhalides have been rigorously evaluated for the photocatalytic degradation of dyes and many synthesis strategies have been employed to enhance this property, relatively little work has been done to test them against pharmaceuticals and pesticides. These persistent organic pollutants are identified as emerging concerns by the EPA and effective strategies must be developed to combat them. Here, we review recent work directed at characterizing the nature of the interactions between bismuth oxyhalides and persistent organic pollutants using techniques including LC-MS/MS for the determination of photocatalytic degradation intermediates and radical scavenging to determine active species during photocatalytic degradation. The reported investigations indicate that the high activity of bismuth oxyhalides for the breakdown of persistent organic pollutants from water can be largely attributed to the strong oxidizing power of electron holes in the valence band. Unlike conventional catalysts like TiO2, these catalysts can also function in ambient solar conditions. This suggests a much wider potential use for these materials as green catalysts for industrial photocatalytic transformation, particularly in flow chemistry applications.

Emerging threats and persistent conservation challenges for freshwater biodiversity

In the 12 years since Dudgeon et al. (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth's surface, these ecosystems host at least 9.5% of the Earth's described animal species. Furthermore, using the World Wide Fund for Nature's Living Planet Index, freshwater population declines (83% between 1970 and 2014) continue to outpace contemporaneous declines in marine or terrestrial systems. The Anthropocene has brought multiple new and varied threats that disproportionately impact freshwater systems. We document 12 emerging threats to freshwater biodiversity that are either entirely new since 2006 or have since intensified: (i) changing climates; (ii) e-commerce and invasions; (iii) infectious diseases; (iv) harmful algal blooms; (v) expanding hydropower; (vi) emerging contaminants; (vii) engineered nanomaterials; (viii) microplastic pollution; (ix) light and noise; (x) freshwater salinisation; (xi) declining calcium; and (xii) cumulative stressors. Effects are evidenced for amphibians, fishes, invertebrates, microbes, plants, turtles and waterbirds, with potential for ecosystem-level changes through bottom-up and top-down processes. In our highly uncertain future, the net effects of these threats raise serious concerns for freshwater ecosystems. However, we also highlight opportunities for conservation gains as a result of novel management tools (e.g. environmental flows, environmental DNA) and specific conservation-oriented actions (e.g. dam removal, habitat protection policies, managed relocation of species) that have been met with varying levels of success. Moving forward, we advocate hybrid approaches that manage fresh waters as crucial ecosystems for human life support as well as essential hotspots of biodiversity and ecological function. Efforts to reverse global trends in freshwater degradation now depend on bridging an immense gap between the aspirations of conservation biologists and the accelerating rate of species endangerment.

The impact of propranolol, 17α-ethinylestradiol, and gemfibrozil on early life stages of marine organisms: effects and risk assessment

Pharmaceuticals are ubiquitously detected in the marine environment at the ng-μg/L range. Given their biological activity, these compounds are known to induce detrimental effects on biota at relatively low exposure levels; however, whether they affect early life stages of marine species is still unclear. In this study, a set of bioassays was performed to assess the effects of propranolol (PROP), 17-α ethinylestradiol (EE2), and gemfibrozil (GEM) on gamete fertilization and embryonic development of mussels (Mytilus galloprovincialis) and sea urchins (Paracentrotus lividus), and on the survival of seabream (Sparus aurata) larvae. Treatments of PROP (500, 5000, 50,000 ng/L), EE2 (5, 50, 500 ng/L), and GEM (50, 500, 5000 ng/L) were selected to encompass levels comparable or superior to environmental concentrations. Obtained data were tested for dose-response curve fitting and the lowest EC₁₀/LC₁₀ used to calculate risk quotients (RQs) based on the MEC/PNEC. No alteration was induced by PROP on the mussel gamete fertilization, while inhibitory effects were observed at environmental levels of EE2 (500 ng/L) and GEM (5000 ng/L). Fertilization was significantly reduced in sea urchin at all PROP and EE2 dosages. The 48-h exposure to all pharmaceuticals induced the onset of morphological abnormalities in either mussel or sea urchin embryos. Alterations were generally observed at environmentally relevant dosages, except for PROP in mussels, in which alterations occurred only at 50,000 ng/L. A decreased survival of seabream larvae was recorded after 96-h exposure to PROP (all treatments), EE2 (50-500 ng/L), and GEM (500 ng/L). A median RQ > 1 was obtained for all pharmaceuticals, assigning a high risk to their occurrence in marine environments. Overall, results showed that current levels of contamination by pharmaceuticals can impact early stages of marine species, which represent critical junctures in the resilience of coastal ecosystems.

Exposure to ZnO nanoparticles alters neuronal and vascular development in zebrafish: Acute and transgenerational effects mitigated with dissolved organic matter

Exposure to ZnO-nanoparticles (NPs) in embryonic zebrafish reduces hatching rates which can be mitigated with dissolved organic material (DOM). Although hatching rate can be a reliable indicator of toxicity and DOM mitigation potential, a fish that has been exposed to ZnO-NPs or any other toxicant may also exhibit other abnormal phenotypes not readily detected by the unaided eye. In this study, we moved beyond hatching rate analysis to investigate the consequences of ZnO-NPs exposure on the nervous and vascular systems in developing zebrafish. Zebrafish exposed to ZnO-NPs (1-100 ppm) exhibited an array of cellular phenotypes including: abnormal secondary motoneuron (SMN) axonal projections, abnormal dorsal root ganglion development and abnormal blood vessel development. Dissolved Zn (<10 kDa) exposure also caused abnormal SMN axonal projections, but to a lesser extent than ZnO-NPs. The ZnO-NPs-induced abnormal phenotypes were reversed in embryos concurrently exposed with various types of DOM. In these acute mitigation exposure experiments, humic acid and carbohydrate, along with natural organic matter obtained from the Suwannee River in Georgia and Milwaukee River in Wisconsin, were the best mitigators of ZnO-NPs-induced motoneuron toxicity at 96 h post fertilization. Further experiments were performed to determine if the ZnO-NPs-induced, abnormal axonal phenotypes and the DOM mitigated axonal phenotypes could persist across generations. Abnormal SMN axon phenotypes caused by ZnO-NPs-exposure were detected in F1 and F2 generations. These are fish that have not been directly exposed to ZnO-NPs. Fish mitigated with DOM during the acute exposure (F0 generation) had a reduction in abnormal motoneuron axon errors in larvae of subsequent generations. Therefore, ZnO-NPs exposure results in neurotoxicity in developing zebrafish which can persist from one generation to the next. Mitigation with DOM can reverse the abnormal phenotypes in an acute embryonic exposure context, as well as across generations, resulting in healthy fish.

Effects of low, subchronic exposure of 2,4-Dichlorophenoxyacetic acid (2,4-D) and commercial 2,4-D formulations on early life stages of fathead minnows (Pimephales promelas)

Aquatic herbicides are commonly used to control a wide variety of algae and plants, but they also have the potential to contaminate and affect nontarget organisms. However, the impacts of low-level 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide exposure on larval fish are not well understood. We conducted a series of experiments to determine the effects of low concentrations (0.05, 0.50, and 2.00 ppm) of 2 commercial 2,4-D amine salt herbicide formulations (Weedestroy® AM40 [WAM40] and DMA® 4 IVM [DMA4]) and pure 2,4-D on the development and survival of fathead minnows (Pimephales promelas) at various life cycle stages. Larval survival (30 d post hatch [dph]) was decreased following exposure of eggs and larvae to pure 2,4-D (0.50 ppm; p ≤ 0.001), as well as to WAM40 (0.50 and 2.00 ppm; p ≤ 0.001, p ≤ 0.001) and DMA4 (0.50 and 2.00 ppm; p ≤ 0.001, p ≤ 0.001). The results also narrowed the critical window of exposure for effects on survival to the period between fertilization and 14 dph. Development was not negatively altered by any of the compounds tested, although the commercial formulations increased larval total length and mass at 2.00 ppm. Altogether, the results indicate that the use of 2,4-D herbicides for weed control in aquatic ecosystems at current recommended concentrations (<2 ppm whole lake; <4 ppm spot treatment) could present risks to fathead minnow larval survival. Environ Toxicol Chem 2018;37:2550-2559. © 2018 SETAC.

Embryonic exposure to benzo(a)pyrene inhibits reproductive capability in adult female zebrafish and correlation with DNA methylation

This study was conducted to investigate the effects of embryonic short-term exposure to benzo(a)pyrene (BaP), a model polycyclic aromatic hydrocarbon, on ovarian development and reproductive capability in adult female zebrafish. In 1-year-old fish after embryonic exposure to BaP for 96 h, the gonadosomatic indices and the percentage of mature oocytes were significantly decreased in the 0.5, 5 and 50 nmol/L treatments. The spawned egg number, the fertilization rate and the hatching success were significantly reduced, while the malformation rate of the F1 unexposed larvae were increased. The mRNA levels of follicle-stimulating hormone, luteinizing hormone, ovarian cytochrome P450 aromatase cyp19a1a and cyp19b, estrogen receptor esr1 and esr2, and hepatic vitellogenin vtg1 and vtg2 genes, were down-regulated in adult female zebrafish that were exposed to BaP during embryonic stage. Both 17β-estradiol and testosterone levels were reduced in the ovary of adult females. The methylation levels of the gonadotropin releasing hormone (GnRH) gene gnrh3 were significantly increased in the adult zebrafish brain, and those of the GnRH receptor gene gnrhr3 were elevated both in the larvae exposed to BaP and in the adult brain, which might cause the down-regulation of the mRNA levels of gnrh3 and gnrhr3. This epigenetic change caused by embryonic exposure to BaP might be a reason for physiological changes along the brain-pituitary-gonad axis. These results suggest that short-term exposure in early life should be included and evaluated in any risk assessment of pollutant exposure to the reproductive health of fish.

Evaluation of targeted and untargeted effects-based monitoring tools to assess impacts of contaminants of emerging concern on fish in the South Platte River, CO

Rivers in the arid Western United States face increasing influences from anthropogenic contaminants due to population growth, urbanization, and drought. To better understand and more effectively track the impacts of these contaminants, biologically-based monitoring tools are increasingly being used to complement routine chemical monitoring. This study was initiated to assess the ability of both targeted and untargeted biologically-based monitoring tools to discriminate impacts of two adjacent wastewater treatment plants (WWTPs) on Colorado's South Platte River. A cell-based estrogen assay (in vitro, targeted) determined that water samples collected downstream of the larger of the two WWTPs displayed considerable estrogenic activity in its two separate effluent streams. Hepatic vitellogenin mRNA expression (in vivo, targeted) and NMR-based metabolomic analyses (in vivo, untargeted) from caged male fathead minnows also suggested estrogenic activity downstream of the larger WWTP, but detected significant differences in responses from its two effluent streams. The metabolomic results suggested that these differences were associated with oxidative stress levels. Finally, partial least squares regression was used to explore linkages between the metabolomics responses and the chemical contaminants that were detected at the sites. This analysis, along with univariate statistical approaches, identified significant covariance between the biological endpoints and estrone concentrations, suggesting the importance of this contaminant and recommending increased focus on its presence in the environment. These results underscore the benefits of a combined targeted and untargeted biologically-based monitoring strategy when used alongside contaminant monitoring to more effectively assess ecological impacts of exposures to complex mixtures in surface waters.

Acceptance of new sanitation: The role of end-users' pro-environmental personal norms and risk and benefit perceptions

Current sanitation systems are inherently limited in their ability to address the new challenges for (waste)water management that arise from the rising demand to restore resource cycles. These challenges include removal of micropollutants, water (re)use, and nutrient recovery. New opportunities to address these challenges arise from new sanitation, a system innovation that combines elements of source separation, local treatment and reuse, and less use of water. New sanitation is applied, but not yet widespread, in several residential areas in Europe. Implementation is hindered by the lack of insight into the general public's willingness to engage in new sanitation, and the resulting uncertainty about this among decision makers and other stakeholders in wastewater management. Using value-belief-norm theory as a conceptual lens, this paper addresses the individual motivations (pro-environmental personal norms) and personal drivers (benefits) and barriers (risks) for acceptance of new sanitation by the Dutch general public. The results of an online survey (N = 338) indicated that both pro-environmental personal norms and risk and benefit perceptions predict consumers' willingness to accept new sanitation. More specifically, they showed that consumer acceptance is driven by perceived risks relating to the housing market and the need to change behavior, but also by environmental benefits. Overall, new sanitation was favorably evaluated by respondents: 64% indicated that they would likely use new sanitation if they were owner-occupiers. The results of this explorative study are discussed in light of the development of novel sanitation systems that are sensitive to perceptions of end-users and other key stakeholders.

Warmed Winter Water Temperatures Alter Reproduction in Two Fish Species

We examined the spawning success of Fathead Minnows (Pimephales promelas) and Johnny Darters (Etheostoma nigrum) exposed to elevated winter water temperatures typical of streams characterized by anthropogenic thermal inputs. When Fathead Minnows were exposed to temperature treatments of 12, 16, or 20 °C during the winter, spawning occurred at 16 and 20 °C but not 12 °C. Eggs were deposited over 9 weeks before winter spawning ceased. Fathead Minnows from the three winter temperature treatments were then exposed to a simulated spring transition. Spawning occurred at all three temperature treatments during the spring, but fish from the 16° and 20 °C treatment had delayed egg production indicating a latent effect of warm winter temperatures on spring spawning. mRNA analysis of the egg yolk protein vitellogenin showed elevated expression in female Fathead Minnows at 16 and 20 °C during winter spawning that decreased after winter spawning ceased, whereas Fathead Minnows at 12 °C maintained comparatively low expression during winter. Johnny Darters were exposed to 4 °C to represent winter temperatures in the absence of thermal inputs, and 12, 16, and 20 °C to represent varying degrees of winter thermal pollution. Johnny Darters spawned during winter at 12, 16, and 20 °C but not at 4 °C. Johnny Darters at 4 °C subsequently spawned following a simulated spring period while those at 12, 16, and 20 °C did not. Our results indicate elevated winter water temperatures common in effluent-dominated streams can promote out-of-season spawning and that vitellogenin expression is a useful indicator of spawning readiness for fish exposed to elevated winter temperatures.

(Anti-)estrogenic and (anti-)androgenic effects in wastewater during advanced treatment: comparison of three in vitro bioassays

Endocrine-disrupting chemicals are mainly discharged into the environment by wastewater treatment plants (WWTPs) and are known to induce adverse effects in aquatic life. Advanced treatment with ozone successfully removes such organic micropollutants, but an increase of estrogenic effects after the ozonation of hospital wastewater was observed in previous studies. In order to investigate this effect, estrogenic and androgenic as well as anti-estrogenic and anti-androgenic activities were observed during treatment of hospital wastewater using three different effect-based reporter gene bioassays. Despite different matrix influences, sensitivities, and test-specific properties, all assays used obtained comparable results. Estrogenic and androgenic activities were mainly reduced during the biological treatment and further removed during ozonation and sand filtration, resulting in non-detectable agonistic activities in the final effluent. An increased estrogenic activity after ozonation could not be observed in this study. Antagonistic effects were removed in the biological treatment by up to 50 % without further reduction in the advanced treatment. Due to the presence of antagonistic substances within the wastewater, masking effects were probable. Therefore, this study showed the relevance of antagonistic activities at hospital WWTPs and illustrates the need for a better understanding about antagonistic effects.

What happens with organic micropollutants during UV disinfection in WWTPs? A global perspective from laboratory to full-scale

The phototransformation of 18 organic micropollutants (OMPs) commonly detected in wastewater treatment plant (WWTP) effluents was examined attempting to explain their fate during UV disinfection in WWTPs. For this purpose, a lab-scale UV reactor (lamp emitting at 254nm) was used to study the influence of the operational conditions (UV dose, temperature and water matrix) on OMPs abatement and disinfection efficiency. Chemical properties of OMPs and the quality of treated effluent were identified as key factors affecting the phototransformation rate of these compounds. Sampling campaigns were carried out at the inlet and outlet of UV systems of three WWTPs, and the results evidenced that only the most photosensitive compounds, such as sulfamethoxazole and diclofenac, are eliminated. Therefore, despite UV treatment is an effective technology to phototransform OMPs, the UV doses typically applied for disinfection (10-50mJ/cm²) are not sufficient to remove them. Consequently, small modifications (increase of UV dose, use of catalysts) should be applied in WWTPs to enhance the abatement of OMPs in UV systems.

Exposure to wastewater effluent affects fish behaviour and tissue-specific uptake of pharmaceuticals

Pharmaceutical active compounds (PhACs) are increasingly being reported in wastewater effluents and surface waters around the world. The presence of these products, designed to modulate human physiology and behaviour, has created concern over whether PhACs similarly affect aquatic organisms. Though laboratory studies are beginning to address the effects of individual PhACs on fish behaviour, few studies have assessed the effects of exposure to complex, realistic wastewater effluents on fish behaviour. In this study, we exposed a wild, invasive fish species-the round goby (Neogobius melanostomus)-to treated wastewater effluent (0%, 50% or 100% effluent dilutions) for 28days. We then determined the impact of exposure on fish aggression, an important behaviour for territory acquisition and defense. We found that exposure to 100% wastewater effluent reduced the number of aggressive acts that round goby performed. We complimented our behavioural assay with measures of pharmaceutical uptake in fish tissues. We detected 11 of 93 pharmaceutical compounds that we tested for in round goby tissues, and we found that concentration was greatest in the brain followed by plasma, then gonads, then liver, and muscle. Fish exposed to 50% and 100% effluent had higher tissue concentrations of pharmaceuticals and concentrated a greater number of pharmaceutical compounds compare to control fish exposed to no (0%) effluent. Exposed fish also showed increased ethoxyresorufin-O-deethylase (EROD) activity in liver tissue, suggesting that fish were exposed to planar halogenated/polycyclic aromatic hydrocarbons (PHHs/PAHs) in the wastewater effluent. Our findings suggest that fish in effluent-dominated systems may have altered behaviours and greater tissue concentration of PhACs. Moreover, our results underscore the importance of characterizing exposure to multiple pollutants, and support using behaviour as a sensitive tool for assessing animal responses to complex contaminant mixtures, like wastewater effluent.

Tools to minimize interlaboratory variability in vitellogenin gene expression monitoring programs

The egg yolk precursor protein vitellogenin is widely used as a biomarker of estrogen exposure in male fish. However, standardized methodology is lacking and little is known regarding the reproducibility of results among laboratories using different equipment, reagents, protocols, and data analysis programs. To address this data gap we tested the reproducibility across laboratories to evaluate vitellogenin gene (vtg) expression and assessed the value of using a freely available software data analysis program. Samples collected from studies of male fathead minnows (Pimephales promelas) exposed to 17α-ethinylestradiol (EE2) and minnows exposed to processed wastewater effluent were evaluated for vtg expression in 4 laboratories. Our results indicate reasonable consistency among laboratories if the free software for expression analysis LinRegPCR is used, with 3 of 4 laboratories detecting vtg in fish exposed to 5 ng/L EE2 (n = 5). All 4 laboratories detected significantly increased vtg levels in 15 male fish exposed to wastewater effluent compared with 15 male fish held in a control stream. Finally, we were able to determine that the source of high interlaboratory variability from complementary deoxyribonucleic acid (cDNA) to quantitative polymerase chain reaction (qPCR) analyses was the expression analysis software unique to each real-time qPCR machine. We successfully eliminated the interlaboratory variability by reanalyzing raw fluorescence data with independent freeware, which yielded cycle thresholds and polymerase chain reaction (PCR) efficiencies that calculated results independently of proprietary software. Our results suggest that laboratories engaged in monitoring programs should validate their PCR protocols and analyze their gene expression data following the guidelines established in the present study for all gene expression biomarkers. Environ Toxicol Chem 2017;36:3102-3107. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Combined effects of increased temperature and endocrine disrupting pollutants on sex determination, survival, and development across generations

Understanding the combined effects of anthropogenic impacts such as climate change and pollution on aquatic ecosystems is critical. However, little is known about how predicted temperature increases may affect the activity of endocrine disrupting compounds (EDCs), particularly in species with plasticity in sex determination. We investigated the effects of a concomitant increase in temperature and exposure to estrogenic EDCs on reproduction and development in an estuarine model organism (Menidia beryllina) across multiple generations. Parents (P) were exposed to environmental levels of the estrogenic insecticide bifenthrin or ethinylestradiol (EE2) at 22 °C and 28 °C for 14 days prior to the initiation of spawning trials. Embryos in the F1 generation were exposed to EDCs until 21 days post hatch (dph), reared to adulthood in clean water at elevated temperatures, and spawned. F1 sex ratios were significantly influenced by elevated temperature and EDCs, potentially altering adaptive development. We also observed fewer viable offspring and increased developmental deformities in the F1 and F2 generations, with a greater impact on F2 juveniles. These findings enhance our understanding of responses to EDCs in the context of climate change and may demonstrate heritable effects. Our study represents the first multigenerational assessment of elevated temperatures in combination with environmentally relevant concentrations of commonly detected endocrine disruptors in a model vertebrate species.

Combined effects of increased temperature and endocrine disrupting pollutants on sex determination, survival, and development across generations

Understanding the combined effects of anthropogenic impacts such as climate change and pollution on aquatic ecosystems is critical. However, little is known about how predicted temperature increases may affect the activity of endocrine disrupting compounds (EDCs), particularly in species with plasticity in sex determination. We investigated the effects of a concomitant increase in temperature and exposure to estrogenic EDCs on reproduction and development in an estuarine model organism (Menidia beryllina) across multiple generations. Parents (P) were exposed to environmental levels of the estrogenic insecticide bifenthrin or ethinylestradiol (EE2) at 22 °C and 28 °C for 14 days prior to the initiation of spawning trials. Embryos in the F1 generation were exposed to EDCs until 21 days post hatch (dph), reared to adulthood in clean water at elevated temperatures, and spawned. F1 sex ratios were significantly influenced by elevated temperature and EDCs, potentially altering adaptive development. We also observed fewer viable offspring and increased developmental deformities in the F1 and F2 generations, with a greater impact on F2 juveniles. These findings enhance our understanding of responses to EDCs in the context of climate change and may demonstrate heritable effects. Our study represents the first multigenerational assessment of elevated temperatures in combination with environmentally relevant concentrations of commonly detected endocrine disruptors in a model vertebrate species.

Thermal modulation of anthropogenic estrogen exposure on a freshwater fish at two life stages

Human-mediated environmental change can induce changes in the expression of complex behaviors within individuals and alter the outcomes of interactions between individuals. Although the independent effects of numerous stressors on aquatic biota are well documented (e.g., exposure to environmental contaminants), fewer studies have examined how natural variation in the ambient environment modulates these effects. In this study, we exposed reproductively mature and larval fathead minnows (Pimephales promelas) to three environmentally relevant concentrations (14, 22, and 65ng/L) of a common environmental estrogen, estrone (E1), at four water temperatures (15, 18, 21, and 24°C) reflecting natural spring and summer variation. We then conducted a series of behavioral experiments to assess the independent and interactive effects of temperature and estrogen exposure on intra- and interspecific interactions in three contexts with important fitness consequences; reproduction, foraging, and predator evasion. Our data demonstrated significant independent effects of temperature and/or estrogen exposure on the physiology, survival, and behavior of larval and adult fish. We also found evidence suggesting that thermal regime can modulate the effects of exposure on larval survival and predator-prey interactions, even within a relatively narrow range of seasonally fluctuating temperatures. These findings improve our understanding of the outcomes of interactions between anthropogenic stressors and natural abiotic environmental factors, and suggest that such interactions can have ecological and evolutionary implications for freshwater populations and communities.

Characterisation of the transcriptome of male and female wild-type guppy brains with RNA-Seq and consequences of exposure to the pharmaceutical pollutant, 17α-ethinyl estradiol

Waterways are increasingly being contaminated by chemical compounds that can disrupt the endocrinology of organisms. One such compound is 17α-ethinyl estradiol (EE2), a synthetic estrogen used in the contraceptive pill. Despite considerable research interest in the effects of EE2 on reproduction and gene expression, surprisingly, only a few studies have capitalised on technologies, such as next-generation sequencing (NGS), to uncover the molecular pathways related to EE2 exposure. Accordingly, using high-throughput sequencing technologies, the aim of our study was to explore the effects of EE2 on brain transcriptome in wild-type male and female guppy (Poecilia reticulata). We conducted two sets of experiments, where fish were exposed to EE2 (measured concentrations: 8ng/L and 38ng/L) in a flow-through system for 21days. The effects on the brain transcriptome on both males and females were assessed using Illumina sequencing (MiSeq and HiSeq) platform followed by bioinformatics analysis (edgeR, DESeq2). Here, we report that exposure to EE2 caused both up- and downregulation of specific transcript abundances, and affected transcript abundance in a sex-specific manner. Specifically, we found 773 transcripts, of which 60 were male-specific, 61 female-specific and 285 treatment-specific. EE2 affected expression of 165 transcripts in males, with 88 downregulated and 77 upregulated, while in females, 120 transcripts were affected with 62 downregulated and 58 upregulated. Finally, RT-qPCR validation demonstrated that expression of transcripts related to transposable elements, neuroserpin and heat shock protein were significantly affected by EE2-exposure. Our study is the first to report brain transcriptome libraries for guppies exposed to EE2. Not only does our study provide a valuable resource, it offers insights into the mechanisms underlying the feminizing effects on the brains of organisms exposed to environmentally realistic concentrations of EE2.

Reduction of Intersex in a Wild Fish Population in Response to Major Municipal Wastewater Treatment Plant Upgrades

Intersex in fish downstream of municipal wastewater treatment plants (MWWTPs) is a global concern. Consistent high rates of intersex in male rainbow darter (Etheostoma caeruleum) have been reported for several years in the Grand River, in southern Ontario, Canada, in close proximity to two MWWTPs. The larger MWWTP (Kitchener) recently underwent upgrades that included the conversion from a carbonaceous activated sludge to nitrifying activated sludge treatment process. This created a unique opportunity to assess whether upgrades designed to improve effluent quality could also remediate the intersex previously observed in wild fish. Multiple years (2007-2012) of intersex data on male rainbow darter collected before the upgrades at sites associated with the MWWTP outfall were compared with intersex data collected in postupgrade years (2013-2015). These upgrades resulted in a reduction from 70 to 100% intersex incidence (preupgrade) to <10% in postupgrade years. Although the cause of intersex remains unknown, indicators of effluent quality including nutrients, pharmaceuticals, and estrogenicity improved in the effluent after the upgrades. This study demonstrated that investment in MWWTP upgrades improved effluent quality and was associated with an immediate change in biological responses in the receiving environment. This is an important finding considering the tremendous cost of wastewater infrastructure.

Delayed impacts of developmental exposure to 17-α-ethinylestradiol in the self-fertilizing fish Kryptolebias marmoratus

17-α-ethinylestradiol (EE2) is one of the most potent endocrine disrupting compounds found in the aquatic environments, and is known to strongly alter fish reproduction and fitness. While the effects of direct exposure to EE2 are well studied in adults, there is an increasing need to assess the impacts of exposure during early life stages. Sensitivity to pollutants during this critical window can potentially affect the phenotype later in life or in subsequent generations. This study investigated phenotypic outcome of early-life exposure to 17-α-ethinylestradiol during development and in adults of the mangrove rivulus, Kryptolebias marmoratus. Being one of the only two known self-fertilizing hermaphroditic vertebrates, this fish makes it possible to work with genetically identical individuals. Therefore, using rivulus makes it possible to examine, explicitly, the phenotypic effects of environmental variance while eliminating the effects of genetic variance. Genetically identical rivulus were exposed for the first 28days post hatching (dph) to 0, 4 or 120ng/L of EE2, and then were reared in uncontaminated water until 168dph. Growth, egg laying and steroid hormone levels (estradiol, cortisol, 11-ketotestosterone, testosterone) were measured throughout development. Exposed fish showed a reduction in standard length directly after exposure (28dph), which was more pronounced in the 120ng/L group. This was followed by compensatory growth when reared in clean water: all fish recovered a similar size as controls by 91dph. There was no difference in the age at maturity and the proportions of mature, non-mature and male individuals at 168dph. At 4ng/L, fish layed significantly fewer eggs than controls, while, surprisingly, reproduction was not affected at 120ng/L. Despite a decrease in fecundity at 4ng/L, there were no changes in hormones levels at the lower concentration. In addition, there were no significant differences among treatments immediately after exposure. However, 120ng/L exposed fish exhibited significantly higher levels of testosterone at 91 and 168dph and 11-ketotestosterone at 168dph, up to 140days after exposure. These results indicate that early-life exposure to EE2 had both immediate and delayed impacts on the adult's phenotype. While fish growth was impaired during exposure, compensatory growth, reduced fecundity and modification of the endocrine status were observed after exposure ceased.

Practices of pharmaceutical waste generation and discarding in households across Portugal

This work is the first nationwide study in Portugal on pharmaceutical waste generated at households, exploring people's attitudes and risk perception. The waste audit was carried out from September to November 2014, targeting pharmaceutical products kept by a sample of families (n = 244). This campaign was an assignment of VALORMED, the non-profit association that manages waste and packaging from expired and unused pharmaceutical products collected by the pharmacies. On average, each household kept at home 1097 g of pharmaceutical products, of which 20% were in use, 72% were not in use, and 8% were mostly expired products ready to discard. Face-to-face interviews with householders showed that 69% of the respondents claimed returning pharmaceutical waste to the local pharmacy. However, this figure is overrated, probably owing to a possible 'good answer' effect. The barriers identified to proper disposal were mainly established routines and lack of close disposal points. This study also provides an insight into the Portuguese awareness and daily practices concerning pharmaceutical waste, which is the cornerstone of any future strategy to reduce the release of active pharmaceutical ingredients into ecosystems.

Estimating the effects of 17α-ethinylestradiol on stochastic population growth rate of fathead minnows: a population synthesis of empirically derived vital rates

Urban freshwater streams in arid climates are wastewater effluent dominated ecosystems particularly impacted by bioactive chemicals including steroid estrogens that disrupt vertebrate reproduction. However, more understanding of the population and ecological consequences of exposure to wastewater effluent is needed. We used empirically derived vital rate estimates from a mesocosm study to develop a stochastic stage-structured population model and evaluated the effect of 17α-ethinylestradiol (EE2), the estrogen in human contraceptive pills, on fathead minnow Pimephales promelas stochastic population growth rate. Tested EE2 concentrations ranged from 3.2 to 10.9 ng L(-1) and produced stochastic population growth rates (λ S ) below 1 at the lowest concentration, indicating potential for population decline. Declines in λ S compared to controls were evident in treatments that were lethal to adult males despite statistically insignificant effects on egg production and juvenile recruitment. In fact, results indicated that λ S was most sensitive to the survival of juveniles and female egg production. More broadly, our results document that population model results may differ even when empirically derived estimates of vital rates are similar among experimental treatments, and demonstrate how population models integrate and project the effects of stressors throughout the life cycle. Thus, stochastic population models can more effectively evaluate the ecological consequences of experimentally derived vital rates.

Phthalate pollution in an Amazonian rainforest

Phthalates are ubiquitous contaminants and endocrine-disrupting chemicals that can become trapped in the cuticles of insects, including ants which were recognized as good bioindicators for such pollution. Because phthalates have been noted in developed countries and because they also have been found in the Arctic, a region isolated from direct anthropogenic influence, we hypothesized that they are widespread. So, we looked for their presence on the cuticle of ants gathered from isolated areas of the Amazonian rainforest and along an anthropogenic gradient of pollution (rainforest vs. road sides vs. cities in French Guiana). Phthalate pollution (mainly di(2-ethylhexyl) phthalate (DEHP)) was higher on ants gathered in cities and along road sides than on those collected in the pristine rainforest, indicating that it follows a human-mediated gradient of disturbance related to the use of plastics and many other products that contain phthalates in urban zones. Their presence varied with the ant species; the cuticle of Solenopsis saevissima traps higher amount of phthalates than that of compared species. However, the presence of phthalates in isolated areas of pristine rainforests suggests that they are associated both with atmospheric particles and in gaseous form and are transported over long distances by wind, resulting in a worldwide diffusion. These findings suggest that there is no such thing as a "pristine" zone.