•We exposed walleye embryos to naphthenic acid faction components (NAFCs).•NAFCs were derived from fresh oil sands process-affected water.•Newly hatched embryos were assessed for changes in ...expression of fourteen genes.•NAFC exposure was associated with increased cyp1a1, and decreased gpx1b and rps40.•Toxicity to walleye embryos may be linked to cytochrome P450 and oxidative stress.
Naphthenic acid fraction components (NAFCs) are constituents of oil sands process-affected water (OSPW), which is generated as a result of unconventional oil production via surface mining in the Athabasca oil sands region. NAFCs are often considered to be major drivers of OSPW toxicity to various taxa, including fishes. However, the molecular targets of these complex mixtures are not fully elucidated. Here we examined the effects in walleye (Sander vitreus) embryos after exposure to NAFCs extracted from fresh OSPW. Eleutheroembryos (exposed to 0, 4.2 or 8.3mg/L NAFCs from 1day post-fertilization to hatch) were subsampled, measured for growth and deformities, and molecular responses were assessed via real-time polymerase chain reaction (PCR). Fourteen genes were evaluated, with a focus on the aryl-hydrocarbon receptor (AhR) − cytochrome P450 pathway (arnt, cyp1a1), the oxidative stress axis (cat, gst, sod, gpx1b), apoptosis (e.g. casp3, bax and p53), growth factor signaling (e.g. insulin-like growth factors igf1, igf1b, and igf1bp), and tissue differentiation (vim). NAFC exposure was associated with an increase in the expression of cyp1a1, and a decrease in gpx1b and ribosomal protein rps40. These results indicate that NAFC effects on walleye early-life stages may be mediated through oxidative stress via pathways that include AhR.
Unconventional oil production in Alberta's oil sands generates oil sands process-affected water (OSPW), which contains toxic constituents such as naphthenic acid fraction components (NAFCs). There ...have been few studies examining effects of NAFC exposure over long periods of early-life stage development in fish. Here we examined the effects of NAFCs extracted from OSPW to embryo-larval fathead minnow, exposed for 21 days. We compared the sensitivity of fathead minnow to walleye reared to 7 days post-hatch (18–20 days total). EC50s for hatch success, including deformities, and total survival were lower for walleye (10–11 mg/L) than fathead minnow (22–25 mg/L), with little post-hatch mortality observed in either species. NAFC exposure affected larval growth at concentrations below the EC50 in fathead minnow (total mass IC10 14–17 mg/L). These data contribute to an understanding of the developmental stages targeted by oil sands NAFCs, as well as their toxicity in a greater range of relevant taxa.
•NAFCs from OSPW were more toxic to walleye embryos than fathead minnow.•Little or no dose response in mortality was observed after hatch in either species.•Fathead minnow larval growth was a more sensitive endpoint than hatch success.•Chronic, large-volume early-life stage tests (21 days) improve estimates of NAFC toxicity.
Walleye embryos exposed to naphthenic acid fraction components were more sensitive than fathead minnow; embryos were more sensitive than larvae and exposure reduced larval growth.
The extraction of surface mined bitumen from oil sands deposits in northern Alberta, Canada produces large quantities of liquid tailings waste, termed oil sands process-affected water (OSPW), which ...are stored in large tailings ponds. OSPW-derived chemicals from several tailings ponds migrating past containment structures and through groundwater systems pose a concern for surface water contamination. The present study investigated the toxicity of groundwater from near-field sites adjacent to a tailings pond with OPSW influence and far-field sites with only natural oil sands bitumen influence. The acute toxicity of unfractionated groundwater and isolated organic fractions was assessed using a suite of aquatic organisms (Pimephales promelas, Oryzias latipes, Daphnia magna, Hyalella azteca, Lampsilis spp., Ceriodaphnia dubia, Hexagenia spp., and Vibrio fischeri). Assessment of unfractionated groundwater demonstrated toxicity towards all invertebrates in at least one far-field sample, with both near-field and far-field samples with bitumen influence toxic towards P. promelas, while no toxicity was observed for O. latipes. When assessing the unfractionated groundwater and isolated organic fractions from near-field and far-field groundwater sites, P. promelas and H. azteca were the most sensitive to organic components, while D. magna and L. cardium were most sensitive to the inorganic components. Groundwater containing appreciable amounts of dissolved organics exhibited similar toxicities to sensitive species regardless of an OSPW or natural bitumen source. The lack of a clear distinction in relative acute toxicities between near-field and far-field samples indicates that the water-soluble chemicals associated with bitumen are acutely toxic to several aquatic organisms. This result, combined with the similarities in chemical profiles between bitumen-influenced groundwater originating from OSPW and/or natural sources, suggests that the industrial bitumen extraction processes corresponding to the tailings pond in this study are not contributing unique toxic substances to groundwater, relative to natural bitumen compounds present in groundwater flow systems.
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•A novel method for extraction and fractionation of dissolved organics was applied to bitumen-influenced groundwater samples•Groundwater with influence from natural bitumen or OSPW chemicals is acutely toxic•Least and most polar organic fractions were toxic, demonstrating multiple chemical classes cause bitumen organic toxicity•Hyalella azteca and Fathead Minnow were most sensitive to bitumen organic mixtures•Freshwater mussels and Daphnia magna were most sensitive to bitumen inorganics
The present study examines the effects of exposure to oil sands on the early life stages (ELS) off fathead minnows (Pimephales promelas). Sediments within and outside natural oil sand deposits were ...collected from sites along the Athabasca River (AB, Canada). The ELS toxicity tests were conducted with control water, natural oil sands, reference sediments, and oil‐refining wastewater pond sediments. Eggs and larvae were exposed to 0.05 to 25.0 g sediment/L and observed for mortality, hatching, malformations, growth, and cytochrome P4501A induction as measured by immunohistochemistry. Natural bitumen and wastewater pond sediments caused significant hatching alterations and exposure‐related increases in ELS mortality, malformations, and reduced size. Larval deformities included edemas, hemorrhages, and spinal malformations. Exposure to reference sediments and controls showed negligible embryo mortality and malformations and excellent larval survival. Sediment analyses using gas chromatography–mass spectrometry revealed high concentrations of alkyl‐substituted polyaromatic hydrocarbons (PAHs) compared to unsubstituted PAHs in natural oil sands (220–360 μg/g) and oil‐mining wastewater pond sediments (1,300 μg/g). The ELS sediment toxicity tests are rapid and sensitive bioassays that are useful in the assessment of petroleum toxicity to aquatic organisms.
Oil sands development in the lower Athabasca River watershed has raised considerable public and scientific concerns regarding perceived effects on environmental health. To address this issue for ...tributaries and the mainstem of the Athabasca River in the Athabasca Oil Sands Region, the Water Component of the Joint Oil Sands Monitoring (JOSM) plan produced monitoring assessments for seven integrated themes: atmospheric deposition, tributary water quality, river mainstem water quality, groundwater quality and quantity, water quality and quantity modelling, benthic invertebrate condition, and fish health. Our review integrates and synthesizes the large and diverse datasets assembled in the seven JOSM theme assessments to (i) evaluate possible environmental effects based on known sources and candidate proximal causes and (ii) determine the importance of cause-and-effect pathways related to contaminant, sediment, and nutrient inputs. Although JOSM research identified ecological effects that appear to be associated with contaminant exposure, the source of this exposure is confounded by co-location of, and inability to differentiate between, oil sands operations (principally released by atmospheric emission) and inputs from the natural bitumen outcrops (e.g., erosional material transported by surface and groundwater flows). Nutrient enrichment from treated municipal sewage effluent was the dominant ecological effect observed for the mainstem Athabasca River, associated with increased fish size and changes in invertebrate assemblages, likely because this pollution source is discharged directly into the river. If the direct release of treated oil sands process water occurs in the future, then the potential ecological impact of these direct industry releases will need to be evaluated carefully. The ecological causal assessment method proved to be a useful tool for better understanding how stressor sources relate to ecological effects through candidate proximate causes. Factors that confound our ability to assess the ecological effects of oil sands development focus on our inability to adequately differentiate between contaminants supplied from natural and anthropogenic contaminant sources. Our causal synthesis identifies options for changes in future monitoring to better anticipate and detect degradation in the ecosystem health of the lower Athabasca River and its tributaries.
This study builds upon the work of a multiagency consortium tasked with determining cost-effective solutions for the effects of pulp mill effluents on fish reproduction. A laboratory fathead minnow ...egg production test and chemical characterization tools were used to benchmark 81 effluents from 20 mills across Canada, representing the major pulping, bleaching, and effluent treatment technologies. For Kraft and mechanical pulp mills, effluents containing less than 20 mg/L BOD
were found to have the greatest probability of having no effects. Organic loading, expressed as the total detected solvent-extractable components by gas chromatography/mass spectrometry (GC/MS), also correlated with decreased egg laying. Exceptions were found for specific Kraft, mechanical, and sulfite mills, suggesting yet unidentified causative agents are involved. Recycled fiber mill effluents, tested for the first time, were found to have little potential for reproductive effects despite large variations in BOD
and GC/MS profiles. Effluent treatment systems across all production types were generally efficient, achieving a combined 82-98% BOD
removal. Further reductions of final effluent organic loadings toward the target of less than 20 mg/L are recommended and can be realized through biotreatment optimization, the reduction of organic losses associated with production upsets and selecting best available technologies that reduce organic loadings to biotreatment.
In Brazil, there are no unified and effective environmental monitoring models for bodies of water. Thus, several methodologies are used that result in information that is often difficult to compare, ...especially for stakeholders involved in regional water management. Studies in some countries such as Australia, Chile, the USA, and Sweden use the monitoring model implemented in Canada that was developed in the early 1990s. This model was designed to evaluate whether the current environmental regulations are sufficiently protective for pulp and paper effluents and for metal mining effluents. In this study, the Canadian Environmental Effects Monitoring methodologies were applied to three different Brazilian river basins, with the goal of constructing a framework for monitoring environmental effects. Pilot studies were carried out in the estuarine regions of the Benevente, Jucu, and Santa Maria da Vitória river basins, which are important rivers in the state of Espírito Santo. Evaluations included fish health, bioaccumulation studies, benthic invertebrate survey, and physical-chemical analyses of water and sediment. The quality of the environments was evaluated by means of seasonal samplings and comparisons between discharge, upstream, and downstream areas. This study made it possible to identify appropriate fish species to be used in environmental effects monitoring and the environmental quality of the rivers themselves as well as knowledge and policy gaps to implement such monitoring programs in Brazil. The study raises questions about the adequacy of Brazilian environmental legislation concerning tidal rivers.
Aquaculture research has indicated that fish embryo hatching success and larval survival can sometimes be predicted by embryo characteristics, such as blastomere cleavage patterns. An analogous ...strategy of individual assessment of spawned eggs could also be used to improve the quality of toxicity tests using early life-stages of fish where control-group survival determines experimental validity. Here we explored whether a simple method of assessing fathead minnow eggs and embryos for abnormalities could predict hatch success, and larval size at hatch, as indicators of embryo larval quality. Embryos were classified according to both their developmental stage and the presence of any abnormalities: uneven blastomere cleavage, atypical embryo size or shape, and the presence of inclusions in the yolk. Clutch size and fertilization rate did not predict embryo larval quality. Fewer abnormalities in embryos with ≤32 cells correlated with longer larvae at hatch. Normal embryos were more likely to hatch successfully than abnormal embryos of the same clutch, but because abnormality rates were generally low, much of the variation in hatch success could not be attributed to visible embryo malformations. Blastomere symmetry may be a useful selection criterion in embryos <3 h postfertilization. Where toxicant exposures early in embryonic development are not required or possible, hatch success could be increased by using older embryos that have survived gastrulation. Purposeful selection of embryos with at least two blastomeres, blastomere symmetry, and few inclusions can improve control survival and improve the quality of any generated (sub)lethality data. In our laboratory, application of the egg-selection criteria significantly improved control group hatch success increasing it from a mean of 84.4 to 94.2 %.
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