Effect-based tools for monitoring and predicting the ecotoxicological effects of chemicals in the aquatic environment

A macrophysiology approach to watershed science and management

Freshwaters are among the most imperiled ecosystems on the planet such that much effort is expended on environmental monitoring to support the management of these systems. Many traditional monitoring efforts focus on abiotic characterization of water quantity or quality and/or indices of biotic integrity that focus on higher scale population or community level metrics such as abundance or diversity. However, these indicators may take time to manifest in degraded systems and delay the identification and restoration of these systems. Physiological indicators manifest rapidly and portend oncoming changes in populations that can hasten restoration and facilitate preventative medicine for degraded habitats. Therefore, assessing freshwater ecosystem integrity using physiological indicators of health is a promising tool to improve freshwater monitoring and restoration. Here, we discuss the value of using comparative, longitudinal physiological data collected at a broad spatial (i.e. watershed) scale (i.e. macrophysiology) as a tool for monitoring aquatic ecosystem health within and among local watersheds to develop timely and effective management plans. There are emerging tools and techniques available for rapid, cost-effective, and non-lethal physiological sampling and we discuss how these can be integrated into management using fish as sentinel indicators in freshwater. Although many examples of this approach are relatively recent, we foresee increasing use of macrophysiology in monitoring, and advocate for the development of more standard tools for consistent and reliable assessment.

Impact of Suspended Solids on the Use of LuminoTox to Detect Toxicity of Micropollutants

There is an increasing need for tools to monitor toxicity of contaminants of emerging concern (CECs) in wastewater. The purpose of this work was to assess interferences in the presence of total solids (TS) and total suspended solids (TSS) in the LuminoTox at concentrations typical of those found in municipal secondary effluent (SE) and to evaluate a simple sample enrichment method for increased CEC sensitivity. 4 or 10 µg/L atrazine in different TS concentrations and in corresponding filtrates (TSS removed) exhibited equivalent toxicities. Because the only difference between these two fractions is the TSS, this result demonstrates that, generally, this fraction does not induce toxicity nor interfere with the bioassay. At constant medium-low TS, the LuminoTox was able to detect the presence of 4 µg/L of atrazine but could not distinguish the change in atrazine concentration between 4 and 6 µg/L. No inhibition was observed in the presence of a mix of 14 CECs each at 0.23 µg/L. However, upon sample enrichment by lyophilization (50×), an inhibition of 81 ± 3% was observed. The enriched SE alone (not spiked with CECs) led to an inhibition of 49 ± 1%, indicating the detection of the CEC contribution to toxicity after sample preconcentration. The LuminoTox is a promising tool for monitoring SE; however, if the intent is to detect CECs, enrichment method optimization is required.

Single and combined effects of microplastics and mercury on juveniles of the European seabass (Dicentrarchus labrax): Changes in behavioural responses and reduction of swimming velocity and resistance time

Microplastics and mercury are environmental pollutants of great concern. The main goal of the present study was to investigate the effects of these pollutants, both individually and in binary mixtures, on the swimming performance of juvenile European seabass, Dicentrarchus labrax. Microplastics alone, mercury alone and all the mixtures caused significant reduction of the swimming velocity and resistance time of fish. Moreover, changes in behavioural responses including lethargic and erratic swimming behaviour were observed. These results highlight that fish behavioural responses can be used as sensitive endpoint to establish the effects of contamination by microplastics and also emphasizes the need to assess the combined effects of microplastics and other environmental contaminants, with special attention to the effects on behavioural responses in fish and other aquatic species.

Differential tolerance to nickel between Dreissena polymorpha and Dreissena rostriformis bugensis populations

Differential tolerance to stress is partly responsible for the heterogeneity of biomarker responses between populations of a sentinel species. Although currently used for freshwater biomonitoring, studies concerning inter-populational variability in tolerance to contaminants for the zebra mussel (Dreissena polymorpha) are scarce. Moreover, this well-known invader is currently replaced by another, the quagga mussel (Dreissena rostriformis bugensis). To evaluate the differential tolerance between dreissenids, several populations of both species were exposed to a high concentration of nickel. A LT₅₀ (time when 50% of individuals were dead) was established for each population. Biomarker responses and internal nickel concentration were also measured, to link tolerance with physiological status. Results evidenced that D. polymorpha populations are more heterogeneous and more tolerant than D. r. bugensis ones. For D. polymorpha populations only, LT₅₀ values were positively correlated with the nickel contamination in situ, with higher anti-oxidative defences and a higher Integrated Biomarker Response value in the field. Such findings may be explained by local adaptation and invasion dynamic within each species. The significance of this differential tolerance when using biomarker responses for biomonitoring purposes is thus discussed.

Ecotoxicological effects of binary mixtures of siduron and Cd on mRNA expression in the earthworm Eisenia fetida

This study aimed to investigate the eco-toxicological responses of earthworm (Eisenia fetida) exposed to combined siduron (herbicide) and cadmium (Cd). Eisenia fetida gene expressions including metallothionein (MT) and heat shock protein70 (Hsp70) were analyzed using real-time Polymerase Chain Reaction after individual and combined siduron (0.90, 1.80, 3.60 and 7.20μgcm^-2) and Cd (0.225, 0.45, 0.90 and 1.80μgcm^-2) sublethal exposures. Where, the nature of the toxicological interactions between siduron and Cd in inducing or suppressing MT and Hsp70 expression was determined by applying the Combination index (CI)-isobologram model. The results revealed significant variations in MT and weak changes in Hsp70 expression when the earthworms were exposed to individual Cd. The individual siduron exposure exhibited a significant down-regulation (p<0.01) in MT during all treatments and in Hsp70 expression only at 7.20μgcm^-2 concentration; while the mixtures of siduron and Cd exposures resulted a significant down regulation (p<0.05) in both MT and Hsp70 expressions. Moreover, the combined siduron and Cd exposure revealed nearly additive effect (CI=1) at the lower effect levels and significant synergistic effect (CI<1) at the higher effect levels for both MT and Hsp70 expression. The synergistic effects of combined siduron and Cd suggest that there might be a potential risk connected to the co-occurrence of these chemicals in the environment.

Transcriptomic responses of the endangered freshwater mussel Margaritifera margaritifera to trace metal contamination in the Dronne River, France

The freshwater pearl mussel Margaritifera margaritifera is one of the most threatened freshwater bivalves worldwide. In this study, we aimed (i) to study the processes by which water quality might affect freshwater mussels in situ and (ii) to provide insights into the ecotoxicological significance of water pollution to natural populations in order to provide necessary information to enhance conservation strategies. M. margaritifera specimens were sampled in two close sites located upstream or downstream from an illegal dumping site. The renal transcriptome of these animals was assembled and gene transcription determined by RNA-seq. Correlations between transcription levels of each single transcript and the bioaccumulation of nine trace metals, age (estimated by sclerochronology), and condition index were determined in order to identify genes likely to respond to a specific factor. Amongst the studied metals, Cr, Zn, Cd, and Ni were the main factors correlated with transcription levels, with effects on translation, apoptosis, immune response, response to stimulus, and transport pathways. However, the main factor explaining changes in gene transcription appeared to be the age of individuals with a negative correlation with the transcription of retrotransposon-related genes. To investigate this effect further, mussels were classified into three age classes. In young, middle-aged and old animals, transcription levels were mainly explained by Cu, Zn and age, respectively. This suggests differences in the molecular responses of this species to metals during its lifetime that must be better assessed in future ecotoxicology studies.

European demonstration program on the effect-based and chemical identification and monitoring of organic pollutants in European surface waters

Growing concern about the adverse environmental and human health effects of a wide range of micropollutants requires the development of novel tools and approaches to enable holistic monitoring of their occurrence, fate and effects in the aquatic environment. A European-wide demonstration program (EDP) for effect-based monitoring of micropollutants in surface waters was carried out within the Marie Curie Initial Training Network EDA-EMERGE. The main objectives of the EDP were to apply a simplified protocol for effect-directed analysis, to link biological effects to target compounds and to estimate their risk to aquatic biota. Onsite large volume solid phase extraction of 50 L of surface water was performed at 18 sampling sites in four European river basins. Extracts were subjected to effect-based analysis (toxicity to algae, fish embryo toxicity, neurotoxicity, (anti-)estrogenicity, (anti-)androgenicity, glucocorticoid activity and thyroid activity), to target analysis (151 organic micropollutants) and to nontarget screening. The most pronounced effects were estrogenicity, toxicity to algae and fish embryo toxicity. In most bioassays, major portions of the observed effects could not be explained by target compounds, especially in case of androgenicity, glucocorticoid activity and fish embryo toxicity. Estrone and nonylphenoxyacetic acid were identified as the strongest contributors to estrogenicity, while herbicides, with a minor contribution from other micropollutants, were linked to the observed toxicity to algae. Fipronil and nonylphenol were partially responsible for the fish embryo toxicity. Within the EDP, 21 target compounds were prioritized on the basis of their frequency and extent of exceedance of predicted no effect concentrations. The EDP priority list included 6 compounds, which are already addressed by European legislation, and 15 micropollutants that may be important for future monitoring of surface waters. The study presents a novel simplified protocol for effect-based monitoring and draws a comprehensive picture of the surface water status across Europe.

Sensitivity of the LuminoTox tool to monitor contaminants of emerging concern in municipal secondary wastewater effluent

Contaminants of emerging concern (CECs) are generally poorly removed during conventional wastewater treatment. There is a need for rapid, sensitive and inexpensive methods to monitor the quality of treated wastewater effluent. The purpose of this study was to assess the applicability of the LuminoTox as a tool to monitor municipal secondary effluent (SE) and to determine its sensitivity to the presence of CECs. The effect of exposure method on a 14 CECs mix was explored; 20min in the dark or 30min under light were both recommended as they were sensitive to the detection of CECs in wastewater while providing a short run time. Stabilized aqueous photosynthetic systems (SAPS) detected the 14 CECs mix in the wastewater matrices when they were present at a concentration in the 6μg/L to 50μg/L range. Interference on the biosensors were examined in a range of wastewater characteristics commonly observed in SE and, for most cases, biosensors were not inhibited which suggests that, in most cases, wastewater characteristics would not cause toxic interferences. SAPS detected CECs in SE with different modes of action with the degree of sensitivity of individual CECs developed from experimental and literature values as follows: inhibitors of the plastoquinone binding site within photosystem II>direct or indirect inhibitors of photosynthesis acting on binding sites other than that of the Q_B. SAPS were assessed for their ability to detect residual CECs in SE without sample preparation, however, the effluent examined exhibited minimal inhibition for SAPS II (7±1%) and no inhibition for SAPS I. These results highlight the need for the development of a sample pre-concentration method to increase the biosensor sensitivity towards native CECs. This would allow the LuminoTox to be an effective tool for monitoring wastewater quality with the intent of residual CECs detection.

Differential gene expression of Australian Cricotopus draysoni (Diptera: Chironomidae) populations reveals seasonal association in detoxification gene regulation

Understanding the molecular mechanisms of organismal response to human-derived ecosystem change is recognised as a critical tool in monitoring and managing impacts, especially in freshwater systems. Fundamental to this approach is to determine the genes involved in responding to ecosystem change and detect modifications to their expression and activity in natural populations. Potential targets for this approach include well-known detoxification genes that are upregulated in response to stress. Here, we tested whether expression of such genes varied in association with differences in ecosystem health and could be detected in the field. We sampled populations of the freshwater midge, Cricotopus draysoni, from two geographically proximate sites in southeast Queensland, Australia, which differed in their ecosystem health, at multiple time points. We assessed transcriptome-level differential gene expression and predicted greatest differential expression between sites, associated with organismal responses to local physico-chemical factors. In contrast, we observed a clear and dramatic difference in gene expression – including of known detoxification genes – between time points, specifically between periods at the start and end of the austral summer rainfall when in-stream water levels are most different. These data suggest that these waterways experience greatest pollution load when water levels are high following rainfall events.

Bioaccumulation, distribution and elimination of chlordecone in the giant freshwater prawn Macrobrachium rosenbergii: Field and laboratory studies

Chlordecone is a persistent organochlorine pesticide that has been widely used in Guadeloupe (French West Indies) to control the banana weevil Cosmopolites sordidus from 1972 to 1993. A few years after its introduction, widespread contamination of soils, rivers, wild animals and aquatic organisms was reported. Although high chlordecone concentrations have been reported in several crustacean species, its uptake, internal distribution, and elimination in aquatic species have never been described. This study aimed at investigating the accumulation and tissue distribution of chlordecone in the giant freshwater prawn Macrobrachium rosenbergii, using both laboratory (30 days exposure) and field (8 months exposure) approaches. In addition, depuration in chlordecone-free water was studied. Results showed that chlordecone bioconcentration in prawns was dose-dependent and time-dependent. Moreover, females appeared to be less contaminated than males after 5 and 7 months of exposure, probably due to successive spawning leading in the elimination of chlordecone through the eggs. Chlordecone distribution in tissues of exposed prawns showed that cephalothorax organs, mainly represented by the hepatopancreas, was the most contaminated. Results also showed that chlordecone was accumulated in cuticle, up to levels of 40% of the chlordecone body burden, which could be considered as a depuration mechanism since chlordecone is eliminated with the exuviae during successive moults. Finally, this study underlined the similarity of results obtained in laboratory and field approaches, which highlights their complementarities in the chlordecone behaviour understanding in M. rosenbergii.

Assessing the relevance of a multiplexed methodology for proteomic biomarker measurement in the invertebrate species Gammarus fossarum: A physiological and ecotoxicological study

Recently, a protein sequence database was built specifically for the sentinel non-model species Gammarus fossarum using a proteogenomics approach. A quantitative multiplexed targeted proteomics assay (using Selected Reaction Monitoring mass spectrometry) was then developed for a fast and simultaneous quantification of dozens of biomarker peptides specific of this freshwater sentinel crustacean species. In order to assess the relevance of this breakthrough methodology in ecotoxicology, the response patterns of a panel of 26 peptides reporting for 20 proteins from the Gammarus fossarum proteome with putative key functional roles (homeostasis, osmoregulation, nutrition, reproduction, molting,…) were recorded through male and female reproductive cycles and after exposure to environmental concentrations of cadmium and lead in laboratory-controlled conditions. Based on these results, we validated the implication of annotated vtg-like peptides in the oogenesis process, and the implication of Na⁺/K⁺ ATPase proteins in the molt cycle of organisms. Upon metal (cadmium and lead) contamination, peptides belonging to proteins annotated as involved in antioxidant and detoxification functions, immunity and molting were significantly down-regulated. Overall, this multiplex assay allowed gaining relevant insights upon disruption of different main functions in the sentinel species Gammarus fossarum. This breakthrough methodology in ecotoxicology offers a valid and high throughput alternative to currently used protocols, paving the way for future practical applications of proteogenomics-derived protein biomarkers in chemical risk assessment and environmental monitoring.

Novel N-Arylaminophosphonates Bearing a Pyrrole Moiety and Their Ecotoxicological Properties

A wide range of biological activities of aminophosphonates predisposes them to find applications as anticancer, antiviral, antimicrobial, antifungal, or herbicidal agents. Despite a number of positive aspects of the use of aminophosphonates, their applications may cause a risk to the environment, which is well exemplified by the case of glyphosate. Therefore, scientists see a pressing need to rate ecotoxicity of aminophosphonates. Nowadays, it is recommended to use comprehensive tools to carry out appropriate and effective risk assessments of toxic substances. For these purposes, tests based on the acute toxicity of the luminescent bacteria Aliivibrio fischeri, as well as the measurement of sub-chronic toxicity of the crustacean Heterocypris incongruens seem to be the most convenient. A series of five diphenyl N-arylamino(pyrrole-2-yl)methylphosphonates was synthesized and preliminary evaluation of their ecotoxicological properties was performed. In order to carry out such investigations, we applied the two biotests mentioned above. Results showed that the N-(4-nitrophenyl) derivative was the most toxic for bacteria in comparison to other tested compounds. As for crustaceans, N-phenyl and N-naphthyl derivatives were found to be the most harmful, simultaneously being relatively harmless for bacteria. Such a phenomenon are discussed in correlation with the literature, while its reason is discussed with respect to the aspect of structure of the tested compounds.

Metal contamination in harbours impacts life-history traits and metallothionein levels in snails

Harbours with limited water exchange are hotspots of contaminant accumulation. Antifouling paints (AF) contribute to this accumulation by leaching biocides that may affect non-target species. In several leisure boat harbours and reference areas in the Baltic Sea, chronic exposure effects were evaluated using caging experiments with the snail Theodoxus fluviatilis. We analysed variations in ecologically relevant endpoints (mortality, growth and reproduction) in concert with variation in metallothionein-like proteins (MTLP) levels. The latter is a biomarker of exposure to metals, such as copper (Cu) and zinc (Zn), which are used in AF paints as active ingredient and stabilizer, respectively. In addition, environmental samples (water, sediment) were analysed for metal (Cu and Zn) and nutrient (total phosphorous and nitrogen) concentrations. All life-history endpoints were negatively affected by the exposure, with higher mortality, reduced growth and lower fecundity in the harbours compared to the reference sites. Metal concentrations were the key explanatory variables for all observed adverse effects, suggesting that metal-driven toxicity, which is likely to stem from AF paints, is a source of anthropogenic stress for biota in the harbours.

Acute toxic effect of sewage effluent on the early life phase of an estuarine crab Scylla serrata

The biological quality of secondary treated sewage effluent was evaluated using a toolbox approach, which combined a larval developmental bioassay and measurement of fecal indicator organisms. The zoea developmental toxicity of Scylla serrata from stage I to stage II was determined by exposing to a range of secondary treated sewage concentrations. Results indicated that the relative progress of zoea stage I to zoea stage II negatively correlated with increasing sewage concentrations. Data was analyzed statistically to determine lethal, median lethal, sublethal, low observed effect, and no observed effect concentrations. Water samples collected along the Buckingham canal discharge zone were also analyzed for its toxicity to the larval development. Fecal indicator organisms chosen to determine the water quality were E. coli, enterococci, C. perfrigens, and F+ coliphages. Concentrations of these fecal markers were determined in the raw influent, primary treated effluent, secondary treated effluent, and in four discharge zone sites. Data showed that this biological toolbox is helpful for providing baseline information on the effectiveness of the wastewater treatment and environmental health of the discharge zone.

Survival, reproduction, growth, and parasite resistance of aquatic organisms exposed on-site to wastewater treated by advanced treatment processes

Advanced wastewater treatment technologies are generally known to be an effective tool for reducing micropollutant discharge into the aquatic environment. Nevertheless, some processes such as ozonation result in stable transformation products with often unknown toxicity. In the present study, whole effluents originating from nine different steps of advanced treatment combinations were compared for their aquatic toxicity. Assessed endpoints were survival, growth and reproduction of Lumbriculus variegatus, Daphnia magna and Lemna minor chronically exposed in on-site flow-through tests based on standard guidelines. The treatment combinations were activated sludge treatment followed by ozonation with subsequent filtration by granular activated carbon or biofilters and membrane bioreactor treatment of raw wastewater followed by ozonation. Additionally, the impact of treated wastewater on the immune response of invertebrates was investigated by challenging D. magna with a bacterial endoparasite. Conventionally treated wastewater reduced reproduction of L. variegatus by up to 46%, but did not affect D. magna and L. minor with regard to survival, growth, reproduction and parasite resistance. Instead, parasite susceptibility was significantly reduced in D. magna exposed to conventionally treated as well as ozonated wastewater in comparison to D. magna exposed to the medium control. None of the three test organisms provided clear evidence that wastewater ozonation leads to increased aquatic toxicity. Rather than to the presence of toxic transformation products, the affected performance of L. variegatus could be linked to elevated concentrations of ammonium and nitrite that likely resulted from treatment failures.

The effects of fipronil and the photodegradation product fipronil desulfinyl on growth and gene expression in juvenile blue crabs, Callinectes sapidus, at different salinities

Endocrine disrupting compounds (EDCs) are now widely established to be present in the environment at concentrations capable of affecting wild organisms. Although many studies have been conducted in fish, less is known about effects in invertebrates such as decapod crustaceans. Decapods are exposed to low concentrations of EDCs that may cause infertility, decreased growth, and developmental abnormalities. The objective herein was to evaluate effects of fipronil and its photodegradation product fipronil desulfinyl. Fipronil desulfinyl was detected in the eggs of the decapod Callinectes sapidus sampled off the coast of South Carolina. As such, to examine specific effects on C. sapidus exposed in early life, we exposed laboratory-reared juveniles to fipronil and fipronil desulfinyl for 96h at three nominal concentrations (0.01, 0.1, 0.5μg/l) and two different salinities (10, 30ppt). The size of individual crabs (weight, carapace width) and the expression of several genes critical to growth and reproduction were evaluated. Exposure to fipronil and fipronil desulfinyl resulted in significant size increases in all treatments compared to controls. Levels of expression for vitellogenin (Vtg), an egg yolk precursor, and the ecdysone receptor (EcR), which binds to ecdysteroids that control molting, were inversely correlated with increasing fipronil and fipronil desulfinyl concentrations. Effects on overall growth and on the expression of EcR and Vtg differ depending on the exposure salinity. The solubility of fipronil is demonstrated to decrease considerably at higher salinities. This suggests that fipronil and its photodegradation products may be more bioavailable to benthic organisms as salinity increases, as more chemical would partition to tissues. Our findings suggest that endocrine disruption is occurring through alterations to gene expression in C. sapidus populations exposed to environmental levels of fipronil, and that effects may be dependent upon the salinity at which exposure occurs.

Prior knowledge-based approach for associating contaminants with biological effects: A case study in the St. Croix River basin, MN, WI, USA

Evaluating potential adverse effects of complex chemical mixtures in the environment is challenging. One way to address that challenge is through more integrated analysis of chemical monitoring and biological effects data. In the present study, water samples from five locations near two municipal wastewater treatment plants in the St. Croix River basin, on the border of MN and WI, USA, were analyzed for 127 organic contaminants. Known chemical-gene interactions were used to develop site-specific knowledge assembly models (KAMs) and formulate hypotheses concerning possible biological effects associated with chemicals detected in water samples from each location. Additionally, hepatic gene expression data were collected for fathead minnows (Pimephales promelas) exposed in situ, for 12 d, at each location. Expression data from oligonucleotide microarrays were analyzed to identify functional annotation terms enriched among the differentially-expressed probes. The general nature of many of the terms made hypothesis formulation on the basis of the transcriptome-level response alone difficult. However, integrated analysis of the transcriptome data in the context of the site-specific KAMs allowed for evaluation of the likelihood of specific chemicals contributing to observed biological responses. Thirteen chemicals (atrazine, carbamazepine, metformin, thiabendazole, diazepam, cholesterol, p-cresol, phenytoin, omeprazole, ethyromycin, 17β-estradiol, cimetidine, and estrone), for which there was statistically significant concordance between occurrence at a site and expected biological response as represented in the KAM, were identified. While not definitive, the approach provides a line of evidence for evaluating potential cause-effect relationships between components of a complex mixture of contaminants and biological effects data, which can inform subsequent monitoring and investigation.

Assessing the environmental/human risk of potential genotoxicants in water samples from lacustrine ecosystems: The case of lakes in Western Greece

Lakes, representing major freshwater resources, play a crucial role for both humans and ecosystems. Based on the increasing international interest in the contamination of water resources by genotoxic compounds, the present study aimed to evaluate the genotoxic potential of surface water samples collected from the five (5) lakes (Amvrakia, Lysimachia, Ozeros, Trichonida, Kastraki) located in Aitoloakarnania regional unit (Western Greece). The genotoxic potential of surface water samples was evaluated by employing the Cytokinesis Block MicroNucleus (CBMN) assay in cultured human lymphocytes. In the former assay, lymphocytes were treated with 1, 2 and 5% (v/v) of surface water from each lake. Statistically significant differences (1.7 to 3.3 fold increase in MN frequencies vs. the control) were seen at the dose of 5% (v/v) in all studied lakes. At the dose of 2% (v/v) statistically significant differences (1.7 to 2.6 fold increase in MN frequencies vs. the control) were observed in all studied lakes except Trichonida lake. Finally, at the dose of 1% (v/v) statistically significant differences (2.3 and 2.5 fold increase in MN frequencies vs. the control) were observed in the Ozeros and Lysimachia lakes. The evaluation of the potential genotoxic effects and the analysis of the physicochemical parameters of lakes' surface water samples is a first step in our effort to evaluate the water quality, in terms of the presence and environmental/human risk of genotoxicants in the studied lake ecosystems. The present study showed for the first time the presence of genotoxic substances in surface waters of the studied lakes.

Advances in understanding the mechanisms of mercury toxicity in wild golden grey mullet (Liza aurata) by 1H NMR-based metabolomics

Mercury (Hg) is recognized as a dangerous contaminant due to its bioaccumulation and biomagnification within trophic levels, leading to serious health risks to aquatic biota. Therefore, there is an urgent need to unravel the mechanisms underlying the toxicity of Hg. To this aim, a metabolomics approach based on protonic nuclear magnetic resonance (¹H NMR), coupled with chemometrics, was performed on the gills of wild golden grey mullets L. aurata living in an Hg-polluted area in Ria de Aveiro (Portugal). Gills were selected as target organ due to their direct and continuous interaction with the surrounding environment. As a consequence of accumulated inorganic Hg and methylmercury, severe changes in the gill metabolome were observed, indicating a compromised health status of mullets. Numerous metabolites, i.e. amino acids, osmolytes, carbohydrates, and nucleotides, were identified as potential biomarkers of Hg toxicity in fish gills. Specifically, decrease of taurine and glycerophosphocholine, along with increased creatine level, suggested Hg interference with the ion-osmoregulatory processes. The rise of lactate indicated anaerobic metabolism enhancement. Moreover, the increased levels of amino acids suggested the occurrence of protein catabolism, further supported by the augmented alanine, involved in nitrogenous waste excretion. Increased level of isobutyrate, a marker of anoxia, was suggestive of onset of hypoxic stress at the Hg contaminated site. Moreover, the concomitant reduction in glycerophosphocholine and phosphocholine reflected the occurrence of membrane repair processes. Finally, perturbation in antioxidant defence system was revealed by the depletion in glutathione and its constituent amino acids. All these data were also compared to the differential Hg-induced metabolic responses previously observed in liver of the same mullets (Brandão et al., 2015). Overall, the environmental metabolomics approach demonstrated its effectiveness in the evaluation of Hg toxicity mechanisms in wild fish under realistic environmental conditions, uncovering tissue-specificities regarding Hg toxic effects namely in gills and liver.

Miniature circulatory systems: A new exposure system for ecotoxicological effect assessments in riverine organisms

Long-term effect assessments in ecotoxicological investigations are important, yet there is a lack of suitable exposure systems for these experiments that can be used for riverine species. A cost-efficient miniature circulatory system was developed that was evaluated for its applicability in long-term exposures in 2 stream-dwelling species: brown trout (Salmo trutta) and an amphipod (Gammarus roeseli). In an egg-to-fry exposure of S. trutta, the toxicity of 2 reverse osmosis concentrates was investigated as examples. Control hatching rate of yolk sac fry was 75 ± 7% and thus complies with the Organisation for Economic Co-operation and Development validity criterion (≥66%). The reverse osmosis concentrates did not impair the hatching rate in any tested concentration. In G. roeseli, mortality rates remained below 20% during a 21-d cultivation, fulfilling the common validity criterion in ecotoxicological testing. Mortality was significantly lower when the species was fed with conditioned alder leaves instead of an artificial shrimp food. Finally, a toxicity test on G. roeseli using copper as the test substance revealed median lethal concentration (LC50) values of 156 μg/L after 96 h and 99 μg/L after 264 h, which is in line with literature findings using other accepted exposure units. In conclusion, the miniature circulatory system provides a novel and cost-efficient exposure system for long-term investigations on riverine species that may also be applicable for other species of fishes and macroinvertebrates. Environ Toxicol Chem 2016;35:2827-2833. © 2016 SETAC.

Vitellogenin and vitellogenin receptor gene expression and 20-hydroxyecdysone concentration in Macrobrachium rosenbergii exposed to chlordecone

Chlordecone is a persistent organochlorine pesticide widely used in Guadeloupe (French West Indies) to control the banana weevil Cosmopolites sordidus. Although it was previously highlighted that chlordecone may affect the reproduction and growth of vertebrate species, little information is available on the chlordecone effects in invertebrates. The present study investigated the effects of chlordecone on a hormone and a protein having key roles in reproduction and growth of the decapod crustacean Macrobrachium rosenbergii, by measuring the 20-hydroxyecdysone concentration, vitellogenin, and vitellogenin receptor gene expression, as well as the bioconcentration of chlordecone in exposed prawns. First, the results revealed that chlordecone was accumulated in M. rosenbergii. Then, it was found that Vg and VgR gene expression were increased in male and female M. rosenbergii exposed to chlordecone for 90 and 240 days, while the 20-hydroxyecdysone concentrations were decreased. This work suggests that chlordecone accumulates in prawn tissues and could affect key molecules involved in the reproduction and the growth of the invertebrate M. rosenbergii. However, many questions remain unresolved regarding the impacts of chlordecone on growth and reproduction and the signaling pathways responsible for these effects, as well as the potential role of confounding factors present in in situ studies.

Linking field-based metabolomics and chemical analyses to prioritize contaminants of emerging concern in the Great Lakes basin

The ability to focus on the most biologically relevant contaminants affecting aquatic ecosystems can be challenging because toxicity-assessment programs have not kept pace with the growing number of contaminants requiring testing. Because it has proven effective at assessing the biological impacts of potentially toxic contaminants, profiling of endogenous metabolites (metabolomics) may help screen out contaminants with a lower likelihood of eliciting biological impacts, thereby prioritizing the most biologically important contaminants. The authors present results from a study that utilized cage-deployed fathead minnows (Pimephales promelas) at 18 sites across the Great Lakes basin. They measured water temperature and contaminant concentrations in water samples (132 contaminants targeted, 86 detected) and used ¹ H-nuclear magnetic resonance spectroscopy to measure endogenous metabolites in polar extracts of livers. They used partial least-squares regression to compare relative abundances of endogenous metabolites with contaminant concentrations and temperature. The results indicated that profiles of endogenous polar metabolites covaried with at most 49 contaminants. The authors identified up to 52% of detected contaminants as not significantly covarying with changes in endogenous metabolites, suggesting they likely were not eliciting measurable impacts at these sites. This represents a first step in screening for the biological relevance of detected contaminants by shortening lists of contaminants potentially affecting these sites. Such information may allow risk assessors to prioritize contaminants and focus toxicity testing on the most biologically relevant contaminants. Environ Toxicol Chem 2016;35:2493-2502. Published 2016 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.

Micropollutants in European rivers: A mode of action survey to support the development of effect-based tools for water monitoring

Environmental quality monitoring of water resources is challenged with providing the basis for safeguarding the environment against adverse biological effects from exposure to anthropogenic chemicals originating from diffuse and point sources. Although current regulatory efforts focus on monitoring and assessing a few legacy chemicals, many more anthropogenic chemicals are and will become detected in aquatic resources as a result of progress in analytical techniques. Assessing this type of exposure information based on available standard approaches from prospective risk assessment for single chemicals inevitably leads to indication of risk in most surface water bodies. As an alternative to generic assessment approaches, effect-based monitoring approaches are suggested. This offers the advantage of reducing uncertainties of effect extrapolation and additionally accounts for mixture effects. To become a credible complement to chemical monitoring information, however, a better understanding of the capabilities and gaps of available effect-based tools is needed. The authors therefore undertook to 1) compile organic contaminants detected in freshwater monitoring studies, 2) provide a synopsis of the mode of action knowledge available for the detected compounds, 3) perform a hazard ranking to identify priority mixtures, and 4) reflect on the challenges to make bioassays fit for effect-based monitoring. The present Focus article shows that chemical occurrence in European freshwaters seems to be highly variable in composition and relative abundancies. Further, although the present mode of action knowledge remains limited, the authors already see the need for batteries of effect-based tools if a more comprehensive coverage of prevailing effect qualities for mixtures is to be targeted. Finally, they suggest a list of organic compounds that could serve as a reference list for effect-based tool validation studies. Environ Toxicol Chem 2016;35:1887-1899. © 2016 SETAC.

Toxic effects of cisplatin cytostatic drug in mussel Mytilus galloprovincialis

Antineoplastic drugs used in chemotherapy were detected in aquatic environment: despite the very low concentrations (ng L(-1) to ug L(-1)), due to their potent mechanism of action they could have adverse effects on non-target aquatic organisms particularly under chronic exposure. Cisplatin (CDDP) is one of the most effective anticancer drug currently in use but information on its ecotoxicological effects is very limited. In this study, Mytilus galloprovincialis was used to investigate the toxic effects related to CDDP exposure. Mussels were exposed to cisplatin (100 ng L(-1)) for 14 days: antioxidant (superoxide dismutase, catalase, total and selenium-dependent glutathione peroxidase) and phase II (glutathione-S-transferase) enzymes activities, oxidative damage (lipid peroxidation), genotoxicity (DNA damage) and neurotoxicity (acetylcholinesterase) was evaluated. Results indicate that CDDP at tested concentration induce changes in the antioxidant capacity, oxidative stress in target organs (digestive gland and gills) as well as DNA damage in mussel hemocytes and neurotoxicity representing a risk for non-target organisms.

Synthesis, Spectral Characterization of Several Novel Pyrene-Derived Aminophosphonates and Their Ecotoxicological Evaluation Using Heterocypris incongruens and Vibrio fisheri Tests

Four diphenyl pyrene-derived aminophosphonates were synthesized. Attempts were made to synthesize diphenyl N-(R)-α-methylbenzylamino(pyren-1-yl)methylphosphonate (3e) in order to obtain the chiral aminophosphonate bearing a pyrene moiety. Because these attempts failed, dimethyl and dibenzyl N-(R)-α-methylbenzyl substituted aminophosphonates 4 and 5 were synthesized and the predominant diastereoisomer of dimethyl aminophosphonate 4 was isolated. The resolution of the diastereomeric mixture of 5 failed. Aminophosphonates 3a–d and the predominant diastereoisomer of 4 were investigated in terms of their ecotoxicity using tests performed on the ostracode Heterocypris incongruens and the fluorescent bacterium Vibrio fisheri. The tests confirmed the moderate-to-high ecotoxicity of aminophosphonates 3a–d and 4, but no evident correlation between the structure and toxicity has been found.

Heavy metals bioaccumulation in selected tissues of red swamp crayfish: An easy tool for monitoring environmental contamination levels

In this paper we explored the heavy metal bioaccumulation (Cd, Cu, Pb and Zn) in Procambarus clarkii, a crayfish recently suggested as a potential bioindicator for metals pollution in freshwater systems. The present study is focused on crayfishes populations caught in a heavily polluted industrial and in a reference sites (Central Italy), though the results are generalized with a thorough analysis of literature metadata. In agreement with the literature, the hepatopancreas (Hep, detoxification tissues) of the red swamp crayfish showed a higher concentration of heavy metals in comparison to the abdominal muscle (AbM, not detoxification tissues) in the sites under scrutiny. Hep/AbM concentration ratio was dependent on the specific metal investigated and on its sediment contamination level. Specifically we found that Hep/AbM ratio decreases as follows: Cd (11.7)>Cu (5.5)>Pb (3.6)>Zn (1.0) and Pb (4.34)>Cd (3.66)>Zn (1.69)>Cu (0.87) for the industrial and reference sites, respectively. The analysis of our bioaccumulation data as well as of literature metadata allowed to elaborate a specific contamination index (Toxic Contamination Index, TCI), dependent only on the bioaccumulation data of hepatopancreas and abdominal muscle. In the industrial site, TCI expressed values much higher than the unit for Cd and Cu, confirming that these metals were the main contaminants; in contrast for lower levels of heavy metals, as those observed in the reference site for Cu, Zn and Pb, the index provided values below unit. TCI is proposed as a useful and easy tool to assess the toxicity level of contaminated sites by heavy metals in the environmental management.

Establishing mussel behavior as a biomarker in ecotoxicology

Most freshwater mussel species of the Unionoida are endangered, presenting a conservation issue as they are keystone species providing essential services for aquatic ecosystems. As filter feeders with limited mobility, mussels are highly susceptible to water pollution. Despite their exposure risk, mussels are underrepresented in standard ecotoxicological methods. This study aimed to demonstrate that mussel behavioral response to a chemical stressor is a suitable biomarker for the advancement of ecotoxicology methods that aids mussel conservation. Modern software and Hall sensor technology enabled mussel filtration behavior to be monitored real-time at very high resolution. With this technology, we present our method using Anodonta anatina and record their response to de-icing salt pollution. The experiment involved an environmentally relevant 'pulse-exposure' design simulating three subsequent inflow events. Three sublethal endpoints were investigated, Filtration Activity, Transition Frequency (number of changes from opened to closed, or vice versa) and Avoidance Behavior. The mussels presented a high variation in filtration behavior, behaving asynchronously. At environmentally relevant de-icing salt exposure scenarios, A. anatina behavior patterns were significantly affected. Treated mussels' Filtration Activity decreased during periods of very high and long de-icing salt exposure (p<0.001), however, increased during short de-icing salt exposure. Treated mussels' Transition Frequency increased during periods of very high and long de-icing salt exposure (p<0.001), which mirrored the Avoidance Behavior endpoint observed only by mussels under chemical stress. Characteristics of Avoidance Behavior were tighter shell closures with repeated and irregular shell movements which was significantly different to their undisturbed resting behavior (p<0.001). Additionally, we found that mussels were sensitive to a chemical stressor even when the mussel's valves were closed. Due to the effects of de-icing salt pollution on freshwater mussel behavior, we suggest better management practices for de-icing salt use be implemented. Our experimental method demonstrated that, with the application of current technologies, mussel behavioral response to a chemical stressor can be measured. The tested sublethal endpoints are suitable for mussel ecotoxicology studies. Avoidance Behavior proved to be a potentially suitable endpoint for calculating mussel behavior effect concentration. Therefore we recommend adult mussel behavior as a suitable biomarker for future ecotoxicological research. This method could be applied to other bivalve species and for physical and environmental stressors, such as particulate matter and temperature.

Chronic exposures to low and high concentrations of ibuprofen elicit different gene response patterns in a euryhaline fish

Ibuprofen is one of the most commonly detected pharmaceuticals in wastewater effluent; however, the effects of ibuprofen on aquatic organisms are poorly understood. This study presents the transcriptome-wide response of the inland silverside, Menidia beryllina, to chronic exposure to ibuprofen. At the lowest exposure concentration (0.0115 mg/L), we detected a downregulation of many genes involved in skeletal development, aerobic respiration, and immune function. At the highest exposure concentration (1.15 mg/L), we detected increased expression of regulatory genes in the arachidonic acid metabolism pathway and several immune genes involved in an inflammatory response. Additionally, there was differential expression of genes involved in oxidative stress responses and a downregulation of genes involved in osmoregulation. This study provides useful information for monitoring the effects of this common wastewater effluent contaminant in the environment and for the generation of biomarkers of exposure to ibuprofen that may be transferable to other fish species.

A comparison of the sublethal and lethal toxicity of four pesticides in Hyalella azteca and Chironomus dilutus

Laboratory toxicity testing is the primary tool used for surface water environmental risk assessment; however, there are critical information gaps regarding the sublethal effects of pesticides. In 10-day exposures, we assessed the lethal and sublethal (motility and growth) toxicities of four commonly used pesticides, bifenthrin, permethrin, cyfluthrin, and chlorpyrifos, on two freshwater invertebrates, Chironomus dilutus and Hyalella azteca. Pyrethroids were more toxic than the organophosphate chlorpyrifos in both species. Bifenthrin was most toxic to H. azteca survival and growth. Cyfluthrin was most toxic to C. dilutus. However, cyfluthrin had the greatest effect on motility on both H. azteca and C. dilutus. The evaluated concentrations of chlorpyrifos did not affect C. dilutus motility or growth, but significantly impacted H. azteca growth. Motility served as the most sensitive endpoint in assessing sublethal effects at low concentrations for both species, while growth was a good indicator of toxicity for all four pesticides for H. azteca. The integration of sublethal endpoints in ambient water monitoring and pesticide regulation efforts could improve identification of low-level pesticide concentrations that may eventually cause negative effects on food webs and community structure in aquatic environments.

Assessment of water pollution in the Brazilian Pampa biome by means of stress biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii (Anura: Hylidae)

The Brazilian Pampa biome is currently under constant threat due to increase of agriculture and improper management of urban effluents. Studies with a focus on the assessment of impacts caused by human activities in this biome are scarce. In the present study, we measured stress-related biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii, an endemic species to the Pampa biome, and tested its suitability as a bioindicator for the assessment of potential aquatic contamination in selected ponds (S1 and S2) nearby agricultural areas in comparison to a reference site. A significant decrease in acetylcholinesterase activity was observed in S2 when compared to S1 and reference. The levels of total-hydroperoxides were increased in S2 site. In parallel, increased activity of the antioxidant enzymes catalase, superoxide dismutase and glutathione S-transferase were observed in S2 when compared to S1 and reference. Further studies are necessary in order to correlate the changes observed here with different chemical stressors in water, as well as to elucidate mechanisms of toxicity induced by pesticides in amphibian species endemic to the Pampa biome. Nevertheless, our study validates Phyllomedusa iheringii as a valuable bioindicator in environmental studies.

Natural Marine and Synthetic Xenobiotics Get on Nematode's Nerves: Neuro-Stimulating and Neurotoxic Findings in Caenorhabditis elegans

Marine algae release a plethora of organic halogenated compounds, many of them with unknown ecological impact if environmentally realistic concentrations are applied. One major compound is dibromoacetic acid (DBAA) which was tested for neurotoxicity in the invertebrate model organism Caenorhabditis elegans (C. elegans). This natural compound was compared with the widespread synthetic xenobiotic tetrabromobisphenol-A (TBBP-A) found in marine sediments and mussels. We found a neuro-stimulating effect for DBAA; this is contradictory to existing toxicological reports of mammals that applied comparatively high dosages. For TBBP-A, we found a hormetic concentration-effect relationship. As chemicals rarely occur isolated in the environment, a combination of both organobromines was also examined. Surprisingly, the presence of DBAA increased the toxicity of TBBP-A. Our results demonstrated that organohalogens have the potential to affect single organisms especially by altering the neurological processes, even with promoting effects on exposed organisms.

The use of growth and behavioral endpoints to assess the effects of pesticide mixtures upon aquatic organisms

Aquatic communities are often subject to complex contaminant mixtures, usually at sublethal concentrations, that can cause long-term detrimental effects. Chemicals within mixtures can effectively interact, resulting in synergism, antagonism or additivity. We investigated the tertiary mixture effects of two pyrethroids, lambda-cyhalothrin and permethrin, and the organophosphate chlorpyrifos, evaluating sublethal endpoints; immobility and growth, on Chironomus dilutus in 10-day exposures. We utilized a toxic units (TU) approach, based on median lethal concentrations (LC50) for each compound. The concepts of independent action and concentration addition were used to compare predicted mixture toxicity to observed mixture toxicity. Increased immobility resulted from mixture concentrations ≥1 TU (7.45 ng/L lambda-cyhalothrin × 24.90 ng/L permethrin × 129.70 ng/L chlorpyrifos), and single pesticides concentrations ≥0.25 TU (5.50 ng/L lambda-cyhalothrin, 24.23 ng/L permethrin, 90.92 ng/L chlorpyrifos, respectively). Growth was inhibited by pesticide mixtures ≥0.125 TU (1.04 ng/L lambda-cyhalothrin × 3.15 ng/L permethrin × 15.47 ng/L chlorpyrifos), and singly by lambda-cyhalothrin ≥0.25 TU (5.50 ng/L), and permethrin ≥0.167 TU (18.21 ng/L). The no observed effect concentrations (NOEC) for immobility and growth, for both mixture and single-pyrethroid exposure, were up to 8.0 and 12.0 times respectively lower than the corresponding NOEC for survival. The median effective concentrations (EC50) for growth (mixture and single-pyrethroid exposure) were up to 7.0 times lower than the respective LC50. This study reinforces that the integration of sublethal endpoints in monitoring efforts is powerful in discerning toxic effects that would otherwise be missed by solely utilizing traditional toxicity assessments.

Sources, occurrence and predicted aquatic impact of legacy and contemporary pesticides in streams

We couple current findings of pesticides in surface and groundwater to the history of pesticide usage, focusing on the potential contribution of legacy pesticides to the predicted ecotoxicological impact on benthic macroinvertebrates in headwater streams. Results suggest that groundwater, in addition to precipitation and surface runoff, is an important source of pesticides (particularly legacy herbicides) entering surface water. In addition to current-use active ingredients, legacy pesticides, metabolites and impurities are important for explaining the estimated total toxicity attributable to pesticides. Sediment-bound insecticides were identified as the primary source for predicted ecotoxicity. Our results support recent studies indicating that highly sorbing chemicals contribute and even drive impacts on aquatic ecosystems. They further indicate that groundwater contaminated by legacy and contemporary pesticides may impact adjoining streams. Stream observations of soluble and sediment-bound pesticides are valuable for understanding the long-term fate of pesticides in aquifers, and should be included in stream monitoring programs.

In vitro bioassays to screen for endocrine active pharmaceuticals in surface and waste waters

In the context of the European Water Framework Directive (WFD) it is fully recognized that pharmaceuticals can represent a relevant issue for the achievement of the good chemical and ecological status of European surface water bodies. The recent European Directive on the review of priority substances in surface water bodies has included three pharmaceuticals of widespread use (diclofenac, 17α-ethinylestradiol (EE2), 17β-estradiol (E2)) in the European monitoring list, the so-called watch list. Endocrine active pharmaceuticals such as EE2 and E2 (also occurring as natural hormone) can cause adverse effects on aquatic ecosystems at very low levels. However, monitoring of these pharmaceuticals within the watch list mechanism of the WFD and national monitoring programs can be difficult because of detection problems of most routine analytical methods. With proposed annual average Environmental Quality Standards (AA-EQS) of 0.035 ng/L and 0.4 ng/L, respectively, the estrogenic pharmaceutical EE2 and the natural hormone E2 are among those substances. Sensitive in vitro bioassays could reduce the current detection problems by measuring the estrogenic activity of environmental samples. In a short review article the application of this approach to screen and assess the risks of endocrine active pharmaceuticals with a focus on estrogenic pharmaceuticals in environmental waters is discussed.

Sublethal effects of the beta-blocker sotalol at environmentally relevant concentrations on the New Zealand mudsnail Potamopyrgus antipodarum

Monitoring sublethal effects of pharmaceuticals on nontarget species in aquatic environments has become an important topic in ecotoxicology, yet few studies have been conducted concerning the effects of beta-blockers on aquatic organisms. The present study investigated the effects of the beta-blocker sotalol (SOT) at 3 environmentally relevant concentrations on life-history traits of the New Zealand mudsnail Potamopyrgus antipodarum. Based on the pharmacodynamic properties of SOT, the authors hypothesized reduced numbers of embryos in the brood pouches, decelerated growth of adult snails, and smaller size of neonates, but no effect on mortality rates of adults. Contrary to the hypothesis, the total number of embryos was significantly higher after 56 d of exposure at nominal concentrations of 0.05 µg/L and 1.0 µg/L by 107% and 73%, respectively. No differences in embryo numbers were observed at earlier time-points. Therefore, the mode of action seems to be an extension of the reproductive period rather than an increase of the embryo production. Furthermore, our results indicate a hormetic dose-response relationship, because no effects were observed at the highest test-concentration (6.5 µg/L). Mortality, growth of adult snails, and neonate sizes were not affected by the beta-blocker. Given the strong influence on reproduction, the effects of sublethal concentrations of SOT and other beta-blockers deserve better consideration in ecotoxicological risk assessment.

The environmental quality of Doñana surrounding areas affects the immune transcriptional profile of inhabitant crayfish Procambarus clarkii

This study aimed to identify differentially expressed genes in Procambarus clarkii crayfish collected from locations of different environmental qualities in the Doñana National Park surrounding areas. The pollution sustained by the crayfish was confirmed by their hepatopancreatic metal concentration. We generated forward and reverse libraries by suppression subtractive hybridization (SSH) to analyze the transcriptional profiles of crayfish from moderately and highly polluted zones in comparison with the control site within the Doñana Biological Reserve. Forty-three differentially expressed genes were detected, and most of them were identified as genes involved in a variety of biological functions, particularly in the innate immune response. To verify the SSH results and assess interindividual variability nine transcripts (ALP, AST, BTF3, CHIT, CTS, ferritin, HC, HC2, and SPINK4) were selected for absolute quantification by real-time qRT-PCR. The qRT-PCR data revealed substantial differences in the absolute amounts of the nine transcripts and confirmed their up- or down-regulation in the polluted sites. Additionally, a positive and significant linear correlation was found between the hepatopancreatic copper concentration and the levels of the transcripts encoding hemocyanins. Finally, the transcriptomic study was complemented with a detailed analysis of SNP profiles of the selected transcripts that revealed point mutations that might underlie adaptive response to environmental stress in P. clarkii. Overall, this work provides novel insights into the molecular pathways that could mediate the response to environmental pollutants in P. clarkii emphasizing the central role of the immune function and thus, should clearly benefit further immunotoxicological research in this organism.

An inexpensive, temporally integrated system for monitoring occurrence and biological effects of aquatic contaminants in the field

Assessment of potential risks of complex contaminant mixtures in the environment requires integrated chemical and biological approaches. In support of the US Great Lakes Restoration Initiative, the US Environmental Protection Agency lab in Duluth, MN, is developing these types of methods for assessing possible risks of aquatic contaminants in near-shore Great Lakes (USA) sites. One component involves an exposure system for caged fathead minnow (Pimephales promelas) adults suitable for the wide range of habitat and deployment situations encountered in and around the Great Lakes. To complement the fish exposure system, the authors developed an automated device for collection of composite water samples that could be simultaneously deployed with the cages and reflect a temporally integrated exposure of the animals. The present study describes methodological details of the design, construction, and deployment of a flexible yet comparatively inexpensive (<600 USD) caged-fish/autosampler system. The utility and performance of the system were demonstrated with data collected from deployments at several Great Lakes sites. For example, over 3 field seasons, only 2 of 130 deployed cages were lost, and approximately 99% of successfully deployed adult fish were recovered after exposures of 4 d or longer. A number of molecular, biochemical, and apical endpoints were successfully measured in recovered animals, changes in which reflected known characteristics of the study sites (e.g., upregulation of hepatic genes involved in xenobiotic metabolism in fish held in the vicinity of wastewater treatment plants). The automated composite samplers proved robust with regard to successful water collection (>95% of deployed units in the latest field season), and low within- and among-unit variations were found relative to programmed collection volumes. Overall, the test system has excellent potential for integrated chemical-biological monitoring of contaminants in a variety of field settings.

Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes

In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River area of concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abnormalities were documented and preserved for microscopic analyses, as were five to eight representative pieces of liver tissue. A piece of dorsal muscle was preserved for stable isotope analyses and otoliths removed for age determination. The incidence of raised skin lesions (mucoid plaques) was high (31 %), however, microscopically only 4.5 % of the white suckers had neoplasia (papillomas). The remaining lesions were epidermal hyperplasia. Superior Bay had the lowest percentage of skin/lip lesions (10 %), while St. Louis Bay had the highest (44 %). St. Louis Bay also had the highest incidence of skin neoplasms (12 %). No hepatocellular neoplasms were documented, however bile duct tumors were observed in 4.5 % of the suckers. Foci of cellular alteration were observed in fish from all sites except the upper AOC. Stable isotope data indicated that most of the suckers relied on the St. Louis River AOC for the majority (>75 %) of their diet, indicating they were resident within the AOC and not in Lake Superior. The amount of diet obtained from the upper estuary was a significant predictor of skin lesion incidence. Hence, habitat use within the AOC appears to be an important risk factor for skin and possibly, liver lesions.

Ethinyl estradiol and other human pharmaceutical estrogens in the aquatic environment: a review of recent risk assessment data

Interest in pharmaceuticals in the environment has increased substantially in recent years. Several studies in particular have assessed human and ecological risks from human pharmaceutical estrogens, such as 17α-ethinyl estradiol (EE2). Regulatory action also has increased, with the USA and other countries developing rules to address estrogens and other pharmaceuticals in the environment. Accordingly, the Center for Drug Evaluation and Research at the US Food and Drug Administration has conducted a review and analysis of current data on the long-term ecological exposure and effects of EE2 and other estrogens. The results indicate that mean-flow long-term predicted environmental concentrations (PECs) of EE2 in approximately 99% or more of US surface water segments downstream of wastewater treatment plants are lower than a predicted no-effect concentration (PNEC) for aquatic chronic toxicity of 0.1 ng/L. Exceedances are expected to be primarily in localized, effluent-dominated water segments. The median mean-flow PEC is more than two orders of magnitude lower than this PNEC. Similar results exist for other pharmaceutical estrogens. Data also suggest that the contribution of EE2 more broadly to total estrogenic load in the environment from all sources (including other human pharmaceutical estrogens, endogenous estrogens, natural environmental estrogens, and industrial chemicals), while highly uncertain and variable, appears to be relatively low overall. Additional data and a more comprehensive approach for data collection and analysis for estrogenic substances in the environment, especially in effluent-dominated water segments in sensitive environments, would more fully characterize the risks.

Transcriptomic effects-based monitoring for endocrine active chemicals: assessing relative contribution of treated wastewater to downstream pollution

The present study investigated whether a combination of targeted analytical chemistry information with unsupervised, data-rich biological methodology (i.e., transcriptomics) could be utilized to evaluate relative contributions of wastewater treatment plant (WWTP) effluents to biological effects. The effects of WWTP effluents on fish exposed to ambient, receiving waters were studied at three locations with distinct WWTP and watershed characteristics. At each location, 4 d exposures of male fathead minnows to the WWTP effluent and upstream and downstream ambient waters were conducted. Transcriptomic analyses were performed on livers using 15,000 feature microarrays, followed by a canonical pathway and gene set enrichment analyses. Enrichment of gene sets indicative of teleost brain-pituitary-gonadal-hepatic (BPGH) axis function indicated that WWTPs serve as an important source of endocrine active chemicals (EACs) that affect the BPGH axis (e.g., cholesterol and steroid metabolism were altered). The results indicated that transcriptomics may even pinpoint pertinent adverse outcomes (i.e., liver vacuolization) and groups of chemicals that preselected chemical analytes may miss. Transcriptomic Effects-Based monitoring was capable of distinguishing sites, and it reflected chemical pollution gradients, thus holding promise for assessment of relative contributions of point sources to pollution and the efficacy of pollution remediation.

Transcriptomic profiling permits the identification of pollutant sources and effects in ambient water samples

Contaminant exposure is one possible contributor to population declines of endangered fish species in the Sacramento-San Joaquin Estuary, California, including the endangered delta smelt (Hypomesus transpacificus). Herein we investigated transcriptional responses in larval delta smelt resulting from exposure to water samples collected at the Department of Water Resources Field Station at Hood, a site of concern, situated upstream of known delta smelt habitat and spawning sites and downstream of the Sacramento Regional Wastewater Treatment Plant (SRWTP). Microarray assessments indicate impacts on energy metabolism, DNA repair mechanisms and RNA processing, the immune system, development and muscle function. Transcription responses of fish exposed to water samples from Hood were compared with exposures to 9% effluent samples from SRWTP, water from the Sacramento River at Garcia Bend (SRGB), upstream of the effluent discharge, and SRGB water spiked with 2mg/L total ammonium (9% effluent equivalent). Results indicate that transcriptomic profiles from Hood are similar to 9% SRWTP effluent and ammonium spiked SRGB water, but significantly different from SRGB. SRGB samples however were also significantly different from laboratory controls, suggesting that SRWTP effluent is not solely responsible for the responses determined at Hood, that ammonium exposure likely enhances the effect of multiple-contaminant exposures, and that the observed mortality at Hood is due to the combination of both effluent discharge and contaminants arising from upstream of the tested sites.

Development of a decision support system to manage contamination in marine ecosystems

In recent years, contamination and its interaction with climate-change variables have been recognized as critical stressors in coastal areas, emphasizing the need for a standardized framework encompassing chemical and biological data into risk indices to support decision-making. We therefore developed an innovative, expert decision support system (Exp-DSS) for the management of contamination in marine coastal ecosystems. The Exp-DSS has two main applications: (i) to determine environmental risk and biological vulnerability in contaminated sites; and (ii) to support the management of waters and sediments by assessing the risk due to the exposure of biota to these matrices. The Exp-DSS evaluates chemical data, both as single compounds and as total toxic pressure of the mixture, to compare concentrations to effect-based thresholds (TELs and PELs). Sites are then placed into three categories of contamination: uncontaminated, mildly contaminated, and highly contaminated. In highly contaminated sites, effects on high-level ecotoxicological endpoints (i.e. survival and reproduction) are used to determine risk at the organism-population level, while ecological parameters (i.e. alterations in community structure and ecosystem functions) are considered for assessing effects on biodiversity. Changes in sublethal biomarkers are utilized to assess the stress level of the organisms in mildly contaminated sites. In Triad studies, chemical concentrations, ecotoxicological high-level effects, and ecological data are combined to determine the level of environmental risk in highly contaminated sites; chemical concentration and ecotoxicological sublethal effects are evaluated to determine biological vulnerability in mildly contaminated sites. The Exp-DSS was applied to data from the literature about sediment quality in estuarine areas of Spain, and ranked risks related to exposure to contaminated sediments from high risk (Huelva estuary) to mild risk (Guadalquivir estuary and Bay of Cadiz). A spreadsheet-based version of the Exp-DSS is available at the MEECE and DiSIT web sites (www.meece.eu and www.disit.unipmn.it).

Cross-species sensitivity to a novel androgen receptor agonist of potential environmental concern, spironolactone

Spironolactone is a pharmaceutical that in humans is used to treat conditions like hirsutism, various dermatologic afflictions, and female-pattern hair loss through antagonism of the androgen receptor. Although not routinely monitored in the environment, spironolactone has been detected downstream of a pharmaceutical manufacturer, indicating a potential for exposure of aquatic species. Furthermore, spironolactone has been reported to cause masculinization of female western mosquitofish, a response indicative of androgen receptor activation. Predictive methods to identify homologous proteins to the human and western mosquitofish androgen receptor suggest that vertebrates would be more susceptible to adverse effects mediated by chemicals like spironolactone that target the androgen receptor compared with invertebrate species that lack a relevant homolog. In addition, an adverse outcome pathway previously developed for activation of the androgen receptor suggests that androgen mimics can lead to reproductive toxicity in fish. To assess this, 21-d reproduction studies were conducted with 2 fish species, fathead minnow and Japanese medaka, and the invertebrate Daphnia magna. Spironolactone significantly reduced the fecundity of medaka and fathead minnows at 50 μg/L, whereas daphnia reproduction was not affected by concentrations as large as 500 μg/L. Phenotypic masculinization of females of both fish species was observed at 5 μg/L as evidenced by formation of tubercles in fathead minnows and papillary processes in Japanese medaka. Effects in fish occurred at concentrations below those reported in the environment. These results demonstrate how a priori knowledge of an adverse outcome pathway and the conservation of a key molecular target across vertebrates can be utilized to identify potential chemicals of concern in terms of monitoring and highlight potentially sensitive species and endpoints for testing.