Comparison of produced water toxicity to Arctic and temperate species.

Produced water is the main discharge stream from oil and gas production. For offshore activities this water is usually discharged to the marine environment. Produced water contains traces of hydrocarbons such as polycyclic aromatic hydrocarbons as well as alkylphenols, which are relatively resistant to biodegradation and have been reported to cause adverse effects to marine organisms in laboratory studies. For management of produced water, risk-based tools have been developed using toxicity data for mainly non-Arctic species. Reliable risk assessment approaches for Arctic environments are requested to manage potential impacts of produced water associated with increased oil and gas activities in Arctic regions. In order to assess the applicability of existing risk tools for Arctic areas, basic knowledge on the sensitivity of Arctic species has to be developed. In the present study, acute and chronic toxicity of artificial produced water for 6 Arctic and 6 temperate species was experimentally tested and evaluated. The hazardous concentrations affecting 5% and 50% of the species were calculated from species sensitivity distribution curves. Hazardous concentrations were compared to elucidate whether temperate toxicity data used in risk assessment are sufficiently representative for Arctic species. From the study it can be concluded that hazardous concentration derived from individual species' toxicity data of temperate and Arctic species are comparable. However, the manner in which Arctic and non-Arctic populations and communities respond to exposure levels above established thresholds remains to be investigated. Hence, responses at higher levels of biological organization should be studied to reveal potential differences in sensitivities to produced water between Arctic and non-Arctic ecosystems.

In vivo effects of environmental concentrations of produced water on the reproductive function of polar cod (Boreogadus saida).

Offshore oil and gas drilling processes generate operational discharges such as produced water (PW), a complex mixture of seawater with polycyclic aromatic hydrocarbons (PAH) and alkylphenols (AP). Some of these compounds may interact with the endocrine system of marine organisms and alter reproductive functions. In this study, polar cod were exposed for up to 28 d to a mixture of PAH, alkylated PAH, and AP simulating the composition of North Sea PW, at low and high concentrations (1:2000 and 1:1000 dilution of the original concentrate, respectively). Potential adverse effects of PW on polar cod physiology were investigated through biomarkers of biotransformation (hepatic ethoxyresorufin O-deethylase [EROD] activity and bile PAH metabolites), endocrine disruption (plasma vitellogenin [VTG] levels and sex steroid concentrations), and gonad histology. Plasma sexual steroid levels in fish were not markedly affected by PW exposure, while higher plasma VTG concentrations were measured in females exposed to the high PW treatment for 7 and 28 d. In males exposed to the higher PW concentration, inhibition of spermatogenesis was observed after 28 d in addition to increase of melano-macrophage occurrence in testis. Females exposed to the high PW treatment for 21 d showed a significant increase of atresia incidence. Finally, a significant decrease in oocyte number was observed in high PW exposed female ovaries after 28 d of exposure.

Ligula intestinalis infection is associated with alterations of both brain and gonad aromatase expression in roach (Rutilus rutilus).

The tapeworm Ligula intestinalis commonly infests roach (Rutilus rutilus) and is responsible for the inhibition of gonad development. In order to better understand the effect of the plerocercoid on fish physiology, and to discriminate parasitization effects from those of endocrine-disrupting compounds (EDC), Cyp19b and Cyp19a aromatase expression was investigated by real-time quantitative polymerase chain reaction (PCR) in brain and gonads of ligulosed roach, caught from a reference site. Data were compared to reproductive and endocrine endpoints previously reported in a larger cohort study (including the sampled population of the present one), such as gonadosomatic index, Fulton index, gonadal histology, plasma sex steroid levels and brain aromatase activity. A decrease in Cyp19b expression in the brain of infected fish was demonstrated, in agreement with the reduction of aromatase activity previously described. In contrast, Cyp19a expression in the gonads appeared to be enhanced in ligulosed fish, in accordance with the presence of immature but differentiated sexual tissues. Together these results show that: (1) L. intestinalis infestation results in an alteration of aromatase expression which, in particular, may have profound effects on the fish brain; and (2) L. intestinalis infection must be considered as a major confounding factor in ecotoxicological studies using aromatase expression as an EDC biomarker. Moreover, the concordance between activity and expression--investigated for the first time in the same population--gives a functional relevance to the transcript aromatase dosage in the brain. Finally, quantitative PCR was confirmed as a sensitive approach, enabling aromatase status to be defined in the poorly developed gonads of ligulosed individuals.

Endocrine effects of the tapeworm Ligula intestinalis in its teleost host, the roach ( Rutilus rutilus).

The effects of parasite infection by the cestode Ligula intestinalis on the reproductive function and endocrine system of wild roach Rutilus rutilus were evaluated. Gonad maturation, plasma vitellogenin, plasma steroid concentrations (i.e. progesterone, 11-keto-testosterone and 17-beta-estradiol) and brain aromatase activity were investigated in relation with parasitization. A low prevalence (8%) of ligulosed roach and a moderate impact of parasitization (mean parasitization index of 8.8%) were found in the studied population. Inhibition of gonad maturation generally resulted from infestation but 5% of the ligulosed roach nevertheless reached maturity. Main sex steroid plasma content was depleted in both genders. Male 11-keto-testosterone, female 17-beta-estradiol and progesterone plasma concentrations of both genders were, respectively, 27, 5 and 3 times lower in ligulosed fish when compared to their non-infected counterparts. Progesterone levels were negatively correlated with the parasitization index in females. Brain aromatase activity of infected roach was reduced to 50% of that of the non-infected fish. These results demonstrate significant negative effects on the reproductive function of wild roach infected by the tapeworm L. intestinalis collected from a site with low contamination.

Effects of dispersed oil exposure on biomarker responses and growth in juvenile wolfish Anarhichas denticulatus.

This study evaluated the sensitivity of the wolfish Anarhichas denticulatus exposed to crude oil, comparing the effects of mechanically dispersed versus chemically dispersed oil using sub-lethal endpoints. To test the toxicity of this controversial technique, two experiments involving exposure of the organisms for 48 h were conducted. The first experiment assessed the effects of oil exposure on biomarker responses. The second experiment monitored the growth of juveniles over 5 weeks after exposure. Overall, this study demonstrated that polycyclic aromatic hydrocarbon (PAH) biliary metabolites, ethoxyresorufin-O-deethylase (EROD), and acetylcholinesterase (AChE) are appropriate biomarkers to assess exposure of A. denticulatus. Growth rate, both in length and weight, was significantly higher in control compared to oil exposure treatments. The lack of differences between chemically and mechanically dispersed oils in biomarker response and growth suggests that dispersant application is no more toxic than the natural oil dispersion. The results indicate the potential for population-level effects resulting from exposure to oil.

In vitro and in vivo studies of the endocrine disrupting potency of cadmium in roach (Rutilus rutilus) liver.

Cadmium has been reported to exert estrogenic, antiestrogenic or both effects in vertebrate species. To elucidate the endocrine disrupting action of CdCl2, ex vivo and in vivo experiments were performed in roach (Rutilus rutilus). Roach liver explants were exposed to a range of CdCl2 concentrations alone (0.1-50µM) or with an effective concentration (100nM) of 17ß-estradiol (E2). In addition, juvenile roach were intraperitoneally injected with CdCl2 (0.1-2.5mg/kg) with or without 1mg E2/kg. Subsequent analysis evaluated the effect of CdCl2 on vitellogenin (VTG) synthesis both at the mRNA and protein level, on estrogen receptors (erα and erß1) and on androgen receptor (ar) mRNA expression. Ex vivo and in vivo experiments indicated that CdCl2 is strongly anti-estrogenic as, when co-exposed to E2, CdCl2 significantly inhibited VTG production as well as vtg and erα mRNA expressions. Moreover, CdCl2 compromised the E2-mediated induction of the ar mRNA expression in vivo.

Evidence of altered fertility in female roach (Rutilus rutilus) from the River Seine (France).

A large variety of anthropogenic chemicals present in the aquatic environment have been shown to be able to alter the endocrine system of exposed organisms, potentially impacting their reproductive function. The aim of this study was to assess the effects of environmental pollution on the reproductive system of wild female roach (Rutilus rutilus) from the Seine River (Normandy, France). A suite of biomarkers of endocrine disruption including gonado-somatic index, plasmatic vitellogenin, gonadal aromatase activity and histological parameters (oocyte diameter and gonad maturation) were studied. Female fish from the polluted sites showed a number of reproductive alterations, including inhibited gonad maturation, reduced oocyte growth, reduced levels of plasmatic vitellogenin and 3-fold lower gonadal aromatase activity than females collected in the reference site. Overall, these results highlight the presence of endocrine disruption in female roach from the Seine River.

Toxicity data for modeling impacts of oil components in an Arctic ecosystem.

Ecological impact assessment modeling systems are valuable support tools for managing impacts from commercial activities on marine habitats and species. The inclusion of toxic effects modeling in these systems is predicated on the availability and quality of ecotoxicology data. Here we report on a data gathering exercise to obtain toxic effects data on oil compounds for a selection of cold-water marine species of fish and plankton associated with the Barents Sea ecosystem. Effects data were collated from historical and contemporary literature resources for the endpoints mortality, development, growth, bioaccumulation and reproduction. Evaluating the utility and applicability of these data for modeling, we find that data coverage is limited to a sub-set of the required endpoints. There is a need for new experimental studies for zooplankton focused on the endpoints development and bioaccumulation and for larvae and juvenile fish focused on growth and development.