Prokaryotic, Microeukaryotic, and Fungal Composition in a Long-Term Polychlorinated Biphenyl-Contaminated Brownfield.

Polychlorinated biphenyls (PCBs) are recognized as persistent organic pollutants and accumulate in organisms, soils, waters, and sediments, causing major health and ecological perturbations. Literature reported PCB bio-transformation by fungi and bacteria in vitro, but data about the in situ impact of those compounds on microbial communities remained scarce while being useful to guide biotransformation assays. The present work investigated for the first time microbial diversity from the three-domains-of-life in a long-term contaminated brownfield (a former factory land). Soil samples were ranked according to their PCB concentrations, and a significant increase in abundance was shown according to increased concentrations. Microbial communities structure showed a segregation from the least to the most PCB-polluted samples. Among the identified microorganisms, Bacteria belonging to Gammaproteobacteria class, as well as Fungi affiliated to Saccharomycetes class or Pleurotaceae family, including some species known to transform some PCBs were abundantly retrieved in the highly polluted soil samples.

Health indicators and contaminant levels of a critically endangered species in the Gironde estuary, the European sturgeon.

The European sturgeon, Acipenser sturio, is a highly endangered species that almost disappeared in the last decades. Thanks to yearly restocking of the population, this species is still found in the Gironde estuary (France), where juveniles grow during several years before leaving to the ocean. The aims of this study were to evaluate the pressure exerted on these fish by known organic and inorganic contaminants during their stay at the Gironde estuary, and to get information on the fish's health in this context. Monthly captures over the year 2014 provided 87 fish from the cohorts 2012 and 2013 mainly, and from cohorts 2008, 2009, and 2011, all fish born in hatchery. We report the very first analyses of contaminant levels and of biological markers measured in the blood of these fish. Low inorganic contamination was found, composed of seven metals mainly Zn (< 5 µg mL-1), Fe (< 1.5 µg mL-1), Cu (< 0.8 µg mL-1), Se (< 0.8 µg mL-1), As (< 0.25 µg mL-1), Co (< 0.14 µg mL-1), and Mn (< 0.03 µg mL-1). Concerning persistent organic contaminants, the sum of seven PCBs varied from 1 to 10 ng g-1 plasma, that of eight OCPs from 0.1 to 1 ng g-1, and that of eight PBDEs from 10 to 100 pg g-1. Higher levels of contaminants were measured during spring as compared to summer. The sex steroid hormone plasma levels (estradiol, testosterone, and 11-ketotestosterone) were quite low, which was predictable for juveniles. The transcription of reproduction-involved genes (EstR, AR, LHR, sox9) in blood cells was demonstrated for the first time. Some of them were correlated with organic contaminant levels PCBs and OCPs. Other gene transcriptions (sodCu and bax) were correlated with PCBs and OCPs. However, the DNA damage level measured here as comet tail DNA and micronuclei ratio in red blood cells were in the very low range of the values commonly obtained in fish from pristine areas. The data presented here can serve as a reference base for future monitoring of this population of sturgeons.

A Bayesian framework for estimating parameters of a generic toxicokinetic model for the bioaccumulation of organic chemicals by benthic invertebrates: Proof of concept with PCB153 and two freshwater species.

Toxicokinetic (TK) models are relevant and widely used to predict chemical concentrations in biological organisms. The importance of dietary uptake for aquatic invertebrates has been increasingly assessed in recent years. However, the model parameters are estimated on limited specific laboratory data sets that are bounded by several uncertainties. The aim of this study was to implement a Bayesian framework for simultaneously estimating the parameters of a generic TK model for benthic invertebrate species from all data collected. We illustrate our approach on the bioaccumulation of PCB153 by two species with different life traits and therefore exposure routes: Chironomus riparius larvae exposed to spiked sediment for 7 days and Gammarus fossarum exposed to spiked sediment and/or leaves for 7 days and then transferred to a clean media for 7 more days. The TK models assuming first-order kinetics were fitted to the data using Bayesian inference. The median model predictions and their 95% credibility intervals showed that the model fit the data well. From a methodological point of view, this paper illustrates that simultaneously estimating all model parameters from all available data by Bayesian inference, while considering the correlation between parameters and different types of data, is a real added value for TK modeling. Moreover, we demonstrated the ability of a generic TK model considering uptake and elimination routes as modules to add according to the availability of the data measured. From an ecotoxicological point of view, we show differences in PCB153 bioaccumulation between chironomids and gammarids, explained by the different life traits of these two organisms.

From Antarctica to the subtropics: Contrasted geographical concentrations of selenium, mercury, and persistent organic pollutants in skua chicks (Catharacta spp.).

Seabirds integrate bioaccumulative contaminants via food intake and have revealed geographical trends of contamination in a variety of ecosystems. Pre-fledging seabird chicks are particularly interesting as bioindicators of chemical contamination, because concentrations in their tissues reflect primarily dietary sources from the local environment. Here we measured 14 trace elements and 18 persistent organic pollutants (POPs) in blood of chicks of skuas that breed in four sites encompassing a large latitudinal range within the southern Indian Ocean, from Antarctica (Adélie Land, south polar skua Catharacta maccormicki), through subantarctic areas (Crozet and Kerguelen Islands, brown skua C. lonnbergi), to the subtropics (Amsterdam Island, C. lonnbergi). Stables isotopes of carbon (δ13C, feeding habitat) and nitrogen (δ15N, trophic position) were also measured to control for the influence of feeding habits on contaminant burdens. Concentrations of mercury (Hg) and selenium (Se) were very high at all the four sites, with Amsterdam birds having the highest concentrations ever reported in chicks worldwide (4.0 ± 0.8 and 646 ± 123 µg g-1 dry weight, respectively). Blood Hg concentrations showed a clear latitudinal pattern, increasing from chicks in Antarctica to chicks in the subantarctic and subtropical islands. Interestingly, blood Se concentrations showed similar between-population differences to Hg, suggesting its involvement in protective mechanisms against Hg toxicity. Chicks' POPs pattern was largely dominated by organochlorine pesticides, in particular DDT metabolites and hexachlorobenzene (HCB). Skua chicks from subantarctic islands presented high concentrations and diversity of POPs. By contrast, chicks from the Antarctic site overall had the lowest concentrations and diversity of both metallic and organic contaminants, with the exception of HCB and arsenic. Skua populations from these sites, being naturally exposed to different quantities of contaminants, are potentially good models for testing toxic effects in developing chicks in the wild.

Wide range of metallic and organic contaminants in various tissues of the Antarctic prion, a planktonophagous seabird from the Southern Ocean.

Trace elements (n=14) and persistent organic pollutants (POPs, n=30) were measured in blood, liver, kidney, muscle and feathers of 10 Antarctic prions (Pachyptila desolata) from Kerguelen Islands, southern Indian Ocean, in order to assess their concentrations, tissue distribution, and inter-tissue and inter-contaminant relationships. Liver, kidney and feathers presented the highest burdens of arsenic, cadmium and mercury, respectively. Concentrations of cadmium, copper, iron, and zinc correlated in liver and muscle, suggesting that uptake and pathways of metabolism and storage were similar for these elements. The major POPs were 4,4'-DDE, mirex, PCB-153 and PCB-138. The concentrations and tissue distribution patterns of environmental contaminants were overall in accordance with previous results in other seabirds. Conversely, some Antarctic prions showed surprisingly high concentrations of BDE-209. This compound has been rarely observed in seabirds before, and its presence in Antarctic prions could be due to the species feeding habits or to the ingestion of plastic debris. Overall, the study shows that relatively lower trophic level seabirds (zooplankton-eaters) breeding in the remote southern Indian Ocean are exposed to a wide range of environmental contaminants, in particular cadmium, selenium and some emerging-POPs, which merits further toxicological investigations.

The mussel caging approach in assessing biological effects of wastewater treatment plant discharges in the Gulf of Finland (Baltic Sea).

Biological effects of wastewater treatment plant (WWTP) effluents were investigated in Baltic mussels (Mytilus trossulus) caged for one month 800m and 1100m from the WWTP discharge site and at a reference site 4km away. Significant antioxidant, genotoxic and lysosomal responses were observed close to the point of the WWTP discharge. Passive samplers (POCIS) attached to the cages indicated markedly higher water concentrations of various pharmaceuticals at the two most impacted sites. Modeling the dispersal of a hypothetical passive tracer compound from the WWTP discharge site revealed differing frequencies and timing of the exposure periods at different caging sites. The study demonstrated for the first time the effectiveness of the mussel caging approach in combination with passive samplers and the application of passive tracer modeling to examine the true exposure patterns at point source sites such as WWTP pipe discharges in the Baltic Sea.

Transcriptome profile analysis reveals specific signatures of pollutants in Atlantic eels.

Identifying specific effects of contaminants in a multi-stress field context remain a challenge in ecotoxicology. In this context, "omics" technologies, by allowing the simultaneous measurement of numerous biological endpoints, could help unravel the in situ toxicity of contaminants. In this study, wild Atlantic eels were sampled in 8 sites presenting a broad contamination gradient in France and Canada. The global hepatic transcriptome of animals was determined by RNA-Seq. In parallel, the contamination level of fish to 8 metals and 25 organic pollutants was determined. Factor analysis for multiple testing was used to identify genes that are most likely to be related to a single factor. Among the variables analyzed, arsenic (As), cadmium (Cd), lindane (γ-HCH) and the hepato-somatic index (HSI) were found to be the main factors affecting eel's transcriptome. Genes associated with As exposure were involved in the mechanisms that have been described during As vasculotoxicity in mammals. Genes correlated with Cd were involved in cell cycle and energy metabolism. For γ-HCH, genes were involved in lipolysis and cell growth. Genes associated with HSI were involved in protein, lipid and iron metabolisms. Our study proposes specific gene signatures of pollutants and their impacts in fish exposed to multi-stress conditions.

Wandering albatrosses document latitudinal variations in the transfer of persistent organic pollutants and mercury to Southern Ocean predators.

Top marine predators are effective tools to monitor bioaccumulative contaminants in remote oceanic environments. Here, we used the wide-ranging wandering albatross Diomedea exulans to investigate potential geographical variations of contaminant transfer to predators in the Southern Ocean. Blood concentrations of 19 persistent organic pollutants and 14 trace elements were measured in a large number of individuals (N = 180) of known age, sex and breeding status from the subantarctic Crozet Islands. Wandering albatrosses were exposed to a wide range of contaminants, with notably high blood mercury concentrations. Contaminant burden was markedly influenced by latitudinal foraging habitats (inferred from blood δ(13)C values), with individuals feeding in warmer subtropical waters having lower concentrations of pesticides, but higher concentrations of mercury, than those feeding in colder subantarctic waters. Sexual differences in contaminant burden seemed to be driven by gender specialization in feeding habitats, rather than physiological characteristics, with females foraging further north than males. Other individual traits, such as adult age and reproductive status, had little effect on blood contaminant concentrations. Our study provides further evidence of the critical role of global distillation on organic contaminant exposure to Southern Ocean avian predators. In addition, we document an unexpected high transfer of mercury to predators in subtropical waters, which merits further investigation.

Abnormal ovarian DNA methylation programming during gonad maturation in wild contaminated fish.

There is increasing evidence that pollutants may cause diseases via epigenetic modifications. Epigenetic mechanisms such as DNA methylation participate in the regulation of gene transcription. Surprisingly, epigenetics research is still limited in ecotoxicology. In this study, we investigated whether chronic exposure to contaminants experienced by wild female fish (Anguilla anguilla) throughout their juvenile phase can affect the DNA methylation status of their oocytes during gonad maturation. Thus, fish were sampled in two locations presenting a low or a high contamination level. Then, fish were transferred to the laboratory and artificially matured. Before hormonal treatment, the DNA methylation levels of the genes encoding for the aromatase and the receptor of the follicle stimulating hormone were higher in contaminated fish than in fish from the clean site. For the hormone receptor, this hypermethylation was positively correlated with the contamination level of fish and was associated with a decrease in its transcription level. In addition, whereas gonad growth was associated with an increase in DNA methylation in fish from the clean site, no changes were observed in contaminated fish in response to hormonal treatment. Finally, a higher gonad growth was observed in fish from the reference site in comparison to contaminated fish.

Pollution biomonitoring in the Bizerte lagoon (Tunisia), using combined chemical and biomarker analyses in grass goby, Zosterisessor ophiocephalus (Teleostei, Gobiidae).

In this study, biological responses and contaminant levels in biological tissues were investigated in grass goby fish specimens (Zosterisessor ophiocephalus) collected from five stations in a moderately polluted ecosystem, namely the Bizerte lagoon on the north coast of Tunisia. The following biomarkers were measured: muscular acetylcholinesterase (AChE), hepatic ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), catalase (CAT), lipoperoxidation (TBARS), condition factor (CF), and hepatosomatic index (HSI). These measurements were taken in parallel with the content of Organochlorine pesticides (OCPs), Polychlorinated biphenyls (PCBs), Polycyclic aromatic hydrocarbons (PAHs) and trace metals (As, Cr, Cu, Mn, Pb, V, Zn, Ag, Cd, Co and Ni) in muscle tissue. Total PAH concentrations ranged from 20.09 ± 0.68 to 105.77 ± 42.58 ng g(-1) dw, PCB from 33.19 ± 6.25 to 126.28 ± 7.37 ng g(-1) dw, OCP from 11.26 ± 1.62 to 19.17 ± 2.06 ng g(-1) dw, and metals from 107.83 ± 1.83 to 187.21 ± 2.00 mg/kg dw. The highest levels of pollutants and biomarkers were observed at station S1, located in the Bizerte channel. Elevated EROD, GST and CAT activities, as well as TBARS levels in liver were positively correlated with tissue contaminant levels at station S1. Significant negative correlations were also found between hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane (DDTs) body burden with AChE activity in muscle at station S2. The integration of biological responses and contaminant tissue content indicated that certain areas of the Bizerte lagoon, notably station S1, are significantly impacted by various human activities, which likely represent a threat for aquatic wildlife. On the basis of these results, and due to its ecological characteristics, the grass goby appears a suitable indicator species for pollution biomonitoring in coastal marine areas along the Mediterranean Sea.

Biliary PAH metabolites, EROD activity and DNA damage in dab (Limanda limanda) from Seine Estuary (France).

The Seine Estuary is well known to be widely contaminated by organic pollutants and especially by polycyclic aromatic hydrocarbons (PAHs). Fish are known to metabolize PAHs, leading to different toxic effects at both cellular and sub-cellular levels. In this work, we studied the relationships between the 7-ethoxyresorufin-O-deethylase (EROD) activity in the liver, the level of DNA strand breaks in blood cells and the concentration of PAH metabolites in the bile of the sentinel flatfish species Limanda limanda. Muscle and liver samples were analysed for parent PAH levels. Female and male dabs of two size classes (juveniles and adults) were collected by trawling in two sites with different degrees of pollution during March and September 2005 and 2006. Significant effects of sex, age, site and season were demonstrated on EROD activity and the level of strand breaks. Parent PAH concentrations in dabs did not allow discriminating of the two sampling sites. However, for PAH metabolites, significant differences were observed with sites and seasons. Dabs collected at the mouth of the estuary appeared to be the most impacted when looking at the results obtained with the three selected markers. The significant correlations observed between the level of PAH metabolites and the level of DNA lesions showed the importance of a combined analysis of chemical and biochemical markers to correctly assess the contribution of chemical contamination to the toxic effects measured in situ in fish.

A new spiked sediment assay using embryos of the Japanese medaka specifically designed for a reliable toxicity assessment of hydrophobic chemicals.

Despite their low water solubility, hydrophobic pollutants are widespread in the aquatic environment and could represent a threat for living organisms. EU regulations on chemicals require accurate and reliable data on chemical toxicity. Current normalised fish toxicity assays, in particular those advocated by OECD guidelines, do not allow reliable toxicity assessment of hydrophobic compounds due to their low water solubility. In order to accurately evaluate the toxicity of this kind of compounds, a new spiked sediment assay using embryos of the Japanese medaka was developed. It consists of directly exposing fertilised eggs, during their entire embryonic development, onto the reference sediment spiked with the test compound. A large set of lethal or sublethal effects in embryos and newly hatched larvae, including non-invasive endpoints is analysed in order to maximise the sensitivity of the test. The approach was validated using four model pollutants with different modes of action: DMBA, PCB126, PCB153 and 4-nonylphenol (NP). All compounds, except PCB153, induced a dose-dependent increase in toxic effects. In fact, lethal effects only occurred at the highest tested concentration. In contrast, sub-lethal effects including skeletal deformations, cardiac activity modulation, body length reduction and hatching delay were observed at low to moderate concentrations of DMBA and PCB126. NP induced subtle effects in embryos, altering cardiac activity and hatching success but only at high concentrations. Although a few more improvements would make it a fully standardised assay, this spiked sediment assay using medaka embryos proves to be sensitive enough to measure hydrophobic chemical toxicity using an environmentally realistic mode of exposure.

A model for estimating the potential biomagnification of chemicals in a generic food web: preliminary development.

GOAL, SCOPE AND BACKGROUND: Bioaccumulation and biomagnification of organic pollutants have been increasingly assessed and modeled during the last years. Due to the complexity of these processes and the large variability of food webs, setting generic assessments for these parameters is really difficult. Equilibrium models, based on a compound's lipophylicity, are the main tool in regulatory proposals, such as for identifying Persistent, Bioaccumulative and Toxic Substances (PBTs), although a refinement has been claimed by the scientific community. Toxicokinetic studies offer an alternative for these estimations, where biomagnification is modeled as a succession of bioaccumulation processes, each one regulated by toxicokinetic parameters. METHODS: A review of kinetic models covering species belonging to different trophic levels and with different ecological behavior has been conducted. The results were employed for setting a conceptual model for estimating the biomagnification potential in a generic food web, which was mathematically implemented through system dynamic models developed under data sheet software. Crystal Ball was then employed for allowing Monte Carlo based probabilistic calculations. Bioaccumulation laboratory assays have been performed to estimate toxicokinetic parameters in mussels (Mytilus edulis) with two PAHs (chrysene and benzo[a]pyrene). The contamination was delivered via food. The exposure period lasted more than one month followed then by a depuration phase. The contaminant content was determined on an individual basis on five replicates. RESULTS AND DISCUSSION: . The reviewed information suggested the development of a tiered conceptual biomagnification model, starting with a simplified food chain which can be refined to more realistic and complex models in successive levels. CONCLUSIONS: The mathematical implementation of the conceptual model offers tools for estimating the potential for bioaccumulation and biomagnification of chemicals under very different conditions. The versatility of the model can be used for both comparative estimations and for validating the model. RECOMMENDATIONS AND PERSPECTIVES: Since bioaccumulation and biomagnification processes are crucial elements for a proper risk assessment of chemicals, their estimation by mathematical models has been widely tested. However, inregulatory assessments, too simplistic models are still being used quite often. The biomagnification model presented in this study should be amore accurate alternative to these models. In comparison to other previously published biomagnification models, the present one covers the time variation of bioaccumulation using just a few toxicokinetic parameters.

Characterization of toxic effects of sediment-associated organic pollutants using the lambda transgenic medaka.

A novel sediment-contact assay using embryos of the transgenic medaka was developed to fully characterize the toxic effects induced by exposure to a mixture of organic pollutants in sediments. Embryos of the lambda transgenic medaka were exposed for 10 days to a clean reference sediment spiked with either the solvent alone, benzo[a]pyrene (B[a]P), or three concentrations (0.3x, 1x, and 2x) of an organic extract (OE) of sediments from the Seine estuary. The 1 x OE-spiked sediment contained concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls similar to those in field-collected sediment. Exposure to this sediment, but not to the B[a]P-spiked sediment, significantly increased embryo-larval mortality and prevalence of spinal deformities. Mutant frequency at the cII mutation target gene in the liver of 10-week-old medaka was significantly increased following exposure to either B[a]P or the three doses of OE. The predominant OE-induced liver mutations were G:C to T:A transversions, consistent with PAHs being the major contributors to the mutation induction. Liver and gonadal tumors were observed in 35-week-old medaka exposed to either B[a]P (1/25) or to the 1 x OE (1/24). The benefits of medaka as a fish model for toxicological assessment and the benefits of the cII mutation assay for mutation detection combine to provide comprehensive assessment of a wide range of genotoxic and nongenotoxic effects of aquatic pollutants.

Biomonitoring in a clean and a multi-contaminated estuary based on biomarkers and chemical analyses in the endobenthic worm Nereis diversicolor.

Relationships between biochemical and physiological biomarkers (acetylcholinesterase [AChE], catalase, and glutathione S-transferase [GST] activities, thiobarbituric acid reactive substances, glycogen, lipids and proteins) and accumulated concentrations of contaminants (polychlorinated biphenyls [PCBs], polycyclic aromatic hydrocarbons and metals) were examined in the keystone species Nereis diversicolor. The chemical analyses of worms and sediments allowed the designation of the Seine estuary and the Authie estuary as a polluted and relatively clean site respectively. Worms from the Seine estuary exhibited higher GST and lower AChE activities. Generally, larger worms had higher concentrations of energy reserves. Principal component analyses clearly highlighted intersite differences: in the first plan, GST activities and chemical concentrations were inversely related to concentrations of energy reserves; in the second one, PCB concentrations and AChE activity were inversely related. Depleted levels of energy reserves could be a consequence of combating toxicants and might predict effects at higher levels of biological organization. The use of GST and AChE activities and energy reserve concentrations as biomarkers is validated in the field in this keystone species.