Detailed Poster Abstract Schedule

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Tuesday, October 3, 2017

Author / Presenter: Leilan Baxter
Affiliation: NovaTox
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Thiamethoxam is a neonicotinoid insecticide used extensively in agriculture across Canada and around the world. It has been detected in surface waters (typically in the ng/L range) next to areas of use, raising questions about possible non-target effects. To better characterize the risk thiamethoxam might pose to freshwater organisms, a series of laboratory and mesocosm studies have been conducted. We report the results of laboratory toxicity testing (acute and chronic) conducted under good laboratory practices (GLP) for over 30 freshwater species (insects, molluscs, crustaceans, algae, macrophytes, and fish). As expected for this compound, fish and primary producers were insensitive, with acute median effect concentrations (LC50 / EC50) observed to be ? 80 mg/L in all cases. Tested molluscs, worms, and rotifers were similarly insensitive (EC50 ? 100 mg/L). In general, insects were the most sensitive group, with most acute EC50 values <1 mg/L. In addition, an outdoor mesocosm study was conducted examining the response of zooplankton, insects, and phytoplankton up to 93 days following a single treatment with thiamethoxam. The No Observed Ecologically Adverse Effect was 100 µg/L and the NOEC community was 30 µg/L. Finally, in order to address the uncertainty of effects associated with possible chronic exposures, a 35-d outdoor mesocosm study with a formulated product was conducted with the mayfly Cloeon dipterum. This species was particularly sensitive to thiamethoxam under chronic exposure conditions in laboratory studies. Significant reductions in both larval abundance and adult emergence were observed at 10.0 and 3.0 ?g/L within 6 to 14 days of exposure, respectively, with transient effects at 1.0 ?g/L. Exposure to 0.1 and 0.3 ?g/L had no statistically significant effect on larval mayfly abundance or adult emergence at any point in the study. These findings support a 35-d NOEC of 0.3 ?g/L for Cloeon dipterum under chronic exposure conditions. Overall, these data will reduce uncertainty in ecological risk assessments of thiamethoxam.

Author / Presenter: Hiba Ben Othman
Affiliation: University of Ottawa
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Information on the effects of chronic, ecologically relevant concentrations of current-use aquatic herbicides on non-target biota is lacking. We determined the effects of the aquatic herbicide diquat on natural phytoplankton communities in outdoor mesocosms (300 L) that included macrophytes as well as amphipods and tadpoles. The experimental design consisted of a control and five treatments (five replicates each) with applications ranging from 6.4 to 100% of the commercial diquat formulation Reward® label rate, which corresponded to concentrations of 74 to 1153 µg/L. Biota were exposed to a single application of diquat for six weeks. Macrophytes were negatively affected across all concentrations within a couple of days and this was followed by a rapid rise in phytoplankton biomass that was proportional to diquat treatment. Both pigment and microscopic analyses showed similar trends in biomass. Phytoplankton communities were dominated by chlorophytes across all treatments. Species diversity was negatively affected by diquat leading to dominance of Chlorella or Scenedesmus spp. depending on the treatment.

Author / Presenter: Markus Brinkmann
Affiliation: University of Saskatchewan
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitously distributed environmental pollutants that mainly originate from petrogenic and pyrogenic sources such as combustion of fossil fuels and other organic material. Various PAHs, including benzo[a]pyrene (BaP), have been demonstrated to cause a wide range of effects in exposed wildlife, including alterations of immune responses, impaired development and reproduction, as well as mutagenesis and carcinogenesis. Most studies to date, however, have used comparably high exposure concentrations, dietary routes of exposure or intraperitoneal injection to administer BaP, and knowledge of low-dose effects at concentrations around water solubility (approx. 4 µg/L) is generally limited. This route of exposure, however, must be considered highly relevant in light of the distribution of PAHs even into remote aquatic systems. To bridge this knowledge gap, early-life stages of the fathead minnow (Pimephales promelas) will be exposed to waterborne BaP as a model compound to characterize toxicity pathways that drive the sensitivity of early life-stage fish to PAHs. Molecular responses at the whole transcriptome, proteome and metabolome level will be investigated at the swim-up stage, and quantitatively correlated with effects on apical (growth, survival, development), histopathological, and biochemical endpoints 28 d post-hatch. The data generated within this experiment will help to better understand the relevance of aqueous exposure to BaP specifically, and PAHs in general, and provide important insights into the relevance of molecular responses in early-life stages as early-warning biomarkers for apical outcomes in juvenile and/or adult fish. This study is part of the EcoToxChip project (@ecotoxchip).

Author / Presenter: Markus Brinkmann
Affiliation: University of Saskatchewan
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Uptake and effects of ionizable organic chemicals in fish can significantly differ as a function of ambient pH. These differences are driven by the rate of passive diffusion of the uncharged species across the gill epithelium, which is considerably greater than that of charged species. Consequently, the flux of chemicals will peak at different pH values depending on their acid dissociation constants. Here, we propose a rapid in vitro screening method to assess the pH-dependent uptake of ionizable organic chemicals, specifically weak acids, at the fish gill. To this end, the permanent rainbow trout gill cell line RTgill-W1 was grown in transwell tissue culture inserts for two to three weeks, and allowed to establish tight monolayers as characterized by stable transepithelial electrical resistance (TEER). After acclimatization to the reduced complexity exposure medium L15/ex at pH 6.0, 7.4, or 8.5, the permeation of chemicals from apical to basal transwell chambers was determined during a 24-h exposure period by means of liquid chromatography with high resolution mass spectrometry (LC-HRMS). The neutral red retention assay was conducted prior to exposures to exclude interference of cytotoxicity with the measurements. The assay was then used to investigate individual model chemicals (chlorophenols, carboxylic acids) and a technical mixture (nonylphenol) that had been previously shown to cause pH-dependent toxicity. To explore the applicability domain of the assay, we chose to investigate the pH-dependent permeation of chemicals present in acidic, neutral, and basic fractions, as well as reconstituted total extracts of oil sands process-affected water (OSPW). The acute toxicity of OSPWs has been shown to be mostly associated with the acidic fraction, specifically naphthenic acids. We observed a substantial pH-dependency of the cytotoxicity and permeability of weak acids, as well as the acidic fraction and reconstituted total extract of OSPW. We conclude that our in vitro assay can be used to screen for pH-dependent uptake and toxicity of ionizable organic chemicals in fish. It is intended to validate the test for application to prediction of pH-dependent uptake and effects in vivo. Thus, it may be a highly valuable tool for in vitro-in vivo extrapolation, and prioritization of chemicals in non-target chemical screenings.

Author / Presenter: Paula Cypas Antunes
Affiliation: AquaTox Testing & Consulting Inc.
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Biological monitoring pursuant to the Metal Mining Effluent Regulations (MMER) showed effects on a benthic invertebrate community in a creek receiving discharges from a combination of municipal, urban, and industrial sources – including treated mine effluent from two facilities. The biological effects observed included an absence of members of the sub-phylum Crustacea. This was consistent with sub-lethal toxicity tests showing reproductive impairment in Ceriodaphnia dubia exposed to the treated mining effluents. To understand the potential for the mining effluent constituents to contribute to the observed effects, a two-part Investigation of Cause (IOC) study was carried out using C. dubia as a surrogate test species. In Part 1, regulated metals were screened based on toxicity and corresponding chemistry data. Based on this assessment, Cu and Ni were put forward as metals of potential concern for effluent discharged from the Waste Water Treatment Plant (Effluent #1) and Ni was put forward for effluent discharged from the Waste Water Treatment System (Effluent #2), while As, Pb, and Zn were eliminated. In Part 2 of the IOC study, toxicity tests with C. dubia (combined with chemical analyses) were conducted on final effluent samples collected over a 1 year period (9 samples for Effluent #1 and 11 samples for Effluent #2). The results of this testing showed consistent reproductive impairment (i.e., calculated IC25s ranging from 15.2% to 74.9% (v/v) and from 1.1 to >100% (v/v) for Effluent #1 and #2, respectively) and comparatively few occurrences of acute lethality. Application of the Toxic Unit (TU) model to the data subsequently showed that all of the total dissolved Ni TUs were higher than the TU IC25s for Effluent #1, thus indicating that levels of Ni were high enough to have caused toxicity. When assessed from a bioavailability perspective (i.e., TUs calculated based on the summed activities of bioavailable Ni species), calculated TUs and TU IC25s diverged even less – with the exception of 2 samples where the bioavailable Ni TUs were much higher than the TU IC25s. Copper was ruled out in Phase 2 of the IOC as dissolved concentrations were well below toxicity threshold values (thus rendering Cu TU values negligible relative to those calculated for Ni). For all Effluent #2 samples, total dissolved Ni TU values similarly indicated that levels of Ni were high enough to cause toxicity and TUs calculated as a function of bioavailable Ni again brought the TUs and TU IC25s closer together. However, for 5 of the samples, the bioavailable Ni TUs remained much higher than the TU IC25. To address the uncertainty prompted by the few samples where TU values were well above the IC25s, correlation analysis was performed to understand water quality impacts on Ni toxicity. This analysis showed that IC25s increased as a function of increasing concentrations of dissolved organic carbon (DOC) for both effluents – a correlation which explained the cases where the Ni TUs and measured IC25s diverged, as the higher DOC in these samples would have offered a protective effect against Ni toxicity. The collective results obtained support a conclusion that Ni was the principal toxicant responsible for the observed impairment to C. dubia reproduction for both Effluent #1 and #2. This study highlights the importance of lab testing as an investigative tool to understanding field effects and building science-based burden of evidence linkages.

Author / Presenter: Julie Dumont
Affiliation: Environment and Climate Change Canada
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

The New Substances Notification Regulations (NSNR) of the Canadian Environmental Protection Act (CEPA) requires the notification of substances new to Canada with prescribed information. These substances are assessed to determine whether they are potentially “toxic,” in order for appropriate control measures to be implemented to mitigate risk to human health and/or the environment. Some substances meet criteria that allows them to be notified as “reduced regulatory requirements” (RRR) polymers. One criterion relates to polymer stability. Polymers that “substantially” degrade, decompose or “depolymerize” do not meet the description of a RRR polymer. An interpretation is that “substantial” be judged against both the degree of degradation, and the influence of the transformation products in risk assessment. Canada’s draft policy regarding that interpretation and its implementation will be explored.

Author / Presenter: Jonathan Fischer-Rush
Affiliation: University of New Brunswick Saint John
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Salmon aquaculture has been present in New Brunswick for over 40 years and is one of the largest industries in the province. However, there have been concerns about the industry’s environmental impacts, because of the release of wastes from the cages. Past studies of such impacts have focused on soft sediment and little is known about impacts on other habitat types. For this reason, we aim to determine if aquaculture-derived nutrients and metals are being incorporated into the nearby benthic community in rocky habitats. Zinc is a micronutrient in salmon feed and is available to nearby organisms through excess feed and feces in the sediments. Meanwhile, copper from antifouling paint leaches into the water, binds to organic material and is also deposited in the sediments. The new organic food source and metal contaminants can be consumed and impact the biology of marine benthic species. We hypothesize that internal metal content as well as the use of aquaculture-derived nutrients will change between species located near and away from pen sites and be feeding type specific. To test this, cages filled with cobble, known as bio-collectors, were placed at paired sites near (<200 m) and away (800-1000 m) from each of 8 aquaculture sites (n=7 per site) in the Bay of Fundy from July to October 2016. Bio-collectors were colonized by a suite of invertebrates and fishes. Three species were analysed for metals and stable isotopes to assess the use of aquaculture wastes: a filter feeder ascidian, Ciona intestinalis, a scavenging fish, Pholis gunnellus, and a predatory fish, Myoxocephalus scorpius. Using dried muscle tissue or whole body samples, we measured concentrations of copper and zinc as well as C, N and S isotopes to evaluate differences between individuals from near and away sites within a species, identify differences between species and compare isotope signatures of each species to that of the salmon feed. While our isotope results are pending, the metal data showed no significant difference between near and away locations for each species. However, there was a difference in the concentration of metals between species. P. gunnellus had copper levels between 1.35 and 1.93 µg/g, while M. scorpius levels ranged between 2.1 and 4.5 ?g/g and C. intestinalis had higher copper values of 5.0 and 17.7 µg/g. Moreover, P. gunnellus, M. scorpius and C. intestinalis had zinc levels between 0.25 and 0.6, 0.4 to 0.6, and 4.53 and 15.9 ?g/g, respectively. Overall, there is little evidence from this study to support that aquaculture-derived metals are being incorporated by benthic species in rocky habitats near pen sites.

Author / Presenter: Jonathan Ford
Affiliation: Wilfrid Laurier University
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Canadian Water Quality guidelines (WQG) are developed from acute and chronic toxicity data, usually done using standard toxicity testing methods. Within the data sets used for deriving WQG, northern species are rarely represented and this represents a gap in our understanding as well as a concern. There is potential that metabolic rate (MR) could be used as an indicator in determining metal toxicity, due to its role in delaying toxicity. The objective of my research will be to determine if metabolic rates can be used as an indicator in determining toxic stress. MR, measured as the rate of oxygen consumption (MO2), will be measured for rainbow trout and fathead minnows. Environmentally relevant concentrations of copper, including the LC50 and LC20 will be used to observe differences in MR during metal exposure between species. Lastly, similar tests will be done using northern caught slimy sculpin (Cottus cognatus) to determine if similar changes are seen. Preliminary results from one trial with added Cu (100 µg/L), control MO2 ranged from 9.75 to 11.75 µmol/g/h (5 cycles, 11.05 ± 0.99 µmol/g/h, mean ± s.d.). When Cu was introduced, the MO2 increased by 45% (3 cycles, approx. 1 h, 15.99 ± 0.88 µmol/g/h, mean ± s.d.). Subsequently, MO2 decreased to 12.13 ± 0.36 µmol (mean ± s.d.). This study will be helpful in determining if water quality guidelines are relevant in the protection of northern species.

Author / Presenter: Jamie Foss
Affiliation: PerkinElmer
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Cannabis, being consumed for both medicinal and recreation purposes in the legalized states of the United States, requires testing for pesticides, since chronic exposure to pesticides can lead to considerable health risks. The State of Oregon has issued regulatory limits for 60 pesticides residues in cannabis flower and edibles. We studied the 60 pesticides spiked in cannabis flower extracts using LC-MS/MS. Pesticides were simultaneously analyzed in both positive and negative mode using electrospray ionization. We were able to detect all the pesticides using this methodology, well below the action limits specified by Oregon. Ground cannabis flower (1 gm) was hydrated with water (5 mL), spiked with pesticide and surrogate standards, followed by the addition of acetonitrile (5 mL). To this mixture, QuEChERS salts (3 gms of MgSO4 and 0.75 gms of sodium acetate) were added, vortexed for 0.5 h and centrifuged at 7000 rpm (5 min). The supernatant was analyze! d directly or furthered cleaned up using dispersive SPE (dSPE containing 150 mg MgSO4, 50 mg PSA, 50 mg C18). Negative controls with no pesticide spikes were taken through the extraction process. The samples were then diluted and injected on column for chromatographic separation followed by detection in multiple monitoring mode (MRM) using the PerkinElmer QSight 210TM mass spectrometer. The pesticides were analyzed using a triple quadrupole mass spectrometer fitted with a hot coaxial flow electrospray ionization source combined with a heated laminar flow interface. The overall sensitivity for most of the pesticides, including those that are normally analyzed by gas chromatography (GC), was between 1-100 ppb, well within the regulatory limits set by the State of Oregon.

Author / Presenter: Melanie Gallant
Affiliation: University of Saskatchewan
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Recent large-scale disease driven population declines have highlighted the need to understand mechanisms of immunotoxicity in amphibians. In vitro assays represent an ideal method for studying the molecular basis of contaminant-induced immunotoxicity. Using the Xenopus A6 cell line, derived from kidney epithelial cells, we are developing an in vitro approach to screen chemicals for their potential to impair the innate immune response in amphibians. Lipopolysaccharide (LPS), a major component of bacterial outer membranes, was used as an immune challenge. Xenopus A6 cells exposed to 1 and 10 µg/ml LPS for 3 and 6 h induced expression of immune-related genes (tumor necrosis factor ? (TNF?), interleukin -1 ? (IL-1?), colony stimulating factor-1 (CSF-1)), indicating the capacity to mount an inflammatory response. Exposure to benzo[a]pyrene (50 ? 3200 ng/ml), a model immunotoxicant, resulted in a dose-dependent increase in the expression of cytochrome P450 1A1 (CYP1A1) but no change in aryl hydrocarbon receptor (AhR) after a 3 h exposure. Results from these assays will be used to design contaminant/pathogen co-exposures to determine if exposure to B[a]P impacts the ability of the cells to respond to an LPS challenge. This in vitro model system will allow us to examine the mechanism of immunotoxicity in amphibians for a variety of environmental contaminants of concern.

Author / Presenter: Derek Green
Affiliation: University of Saskatchewan
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Selenium (Se) is a nonmetal atomic element and essential trace nutrient for all domains of life. However, excess consumption of or exposure to various chemical species of Se can have detrimental effects on organisms that may ultimately lead to death of the individual or extirpation of populations. The most environmentally relevant form of Se is the organic form, selenomethionine (SeM). Selenomethionine is generated by primary producers and subsequently bioaccumulates in aquatic food webs, ultimately causing severe teratogenic effects in oviparous animals (ex. fish, birds) as SeM is incorporated into and maternally transferred by the egg yolk protein, vitellogenin. As anthropogenic activities can cause Se influx to the aquatic environment, it is critically important to determine the toxic mechanisms of and species-specific sensitivities to SeM in order to protect vulnerable populations. This research will use microinjected SeM as an analogue for maternally transferred SeM in four commercially and culturally relevant Canadian fish species: fathead minnows (Pimephales promelas), white sucker (Catostomus commersonii), rainbow trout (Oncorhynchus mykiss), and endangered white sturgeon (Acipenser transmontanus). Biochemical and apical endpoint analyses will be used to determine the relative developmental sensitivities of these species to SeM and to construct adverse outcome pathways (AOPs) for SeM exposure in each species under study. These AOPs will identify the molecular initiating event (MIE) of SeM toxicity as it pertains to downstream deleterious effects on apical endpoints (survival, length, weight, condition, reproductive output, somatic indices, etc.). Omic (genomic, proteomic, transcriptomic, and metabolomic) analyses, biomolecular assays (glutathione:glutathione disulfide ratio, and thiobarbituric acid reactive substances, superoxide dismutase activity, and catalase activity assays), energetic (triglyceride and glycogen) concentrations of muscle and liver, and histological analyses will be used to help identify the MIE of SeM toxicity in these species. The data acquired and AOPs constructed in this research will subsequently aid in the of regulation of Se in the environment, and aid in the risk assessment of SeM exposure to these fish as well as novel species sharing similar biomolecular characteristics, all while minimizing loss of animal life.

Author / Presenter: Che Lu
Affiliation: University of Waterloo
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

In the tributaries and mainstem of the Athabasca River in the oil sands region, inputs of bitumen-derived constituents from natural oil sands as well as potential contaminants associated with mining activities will affect water quality, thus raising concerns of cumulative impacts on aquatic organisms. Erosion of bitumen ore by ice and water leads to the partitioning of constituents into air, water and sediment as a function of the physical and chemical properties of the constituents and the surrounding environment. The partitioning of bitumen-derived constituents influences the exposure to and effects of constituents on aquatic organisms. There is a need to better understand the environmental impacts associated with bitumen-derived constituents as a function of erosional processes in order to address the issue of potential cumulative impacts. The objective of this study was to isolate the dissolved and particulate fractions of bitumen ore mixed with water and evaluate the toxicity of the individual and combined fractions on the survival of Hyalella azteca. Two bitumen ore samples were evaluated; 1) bitumen ore collected from a McMurray Formation exposure in the MacKay River valley and 2) bitumen ore collected from an open pit mine and stored at the InnoTech Sample Bank. Bitumen ore was mechanical mixed for 24 h in water to simulate erosion, and then filtered to separate the dissolved and particulate fractions. Toxicity tests were conducted using a 96-h H. azteca survival test at bitumen concentrations of 0-2.5 dry wt g/L for four different treatments: bitumen ore (unmixed), bitumen ore (mixed), dissolved fraction and particulate fraction. The results for both bitumen ore samples indicate significantly higher toxicity for all treatments that contain particulates relative to the dissolved fraction. Water chemistry analyses of metals and polycyclic aromatic compounds (PAC) were used to estimate threshold concentrations. Threshold concentrations were compared with available data on environmental concentrations of metals and PACs in suspended sediments collected from the Athabasca River. The findings of this study are important to establishing a comprehensive environmental monitoring program and developing an effective watershed management strategy in the oil sand region.

Author / Presenter: Blue Markwart
Affiliation: Toxicology Centre, University of Saskatchewan
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Markwart B.(1), Liber K.(1,2), Hecker M.(2), Janz D.(3), Raes K.(1), Doig L.E.(1) 1. Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3 2. School of Environment and Sustainability, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8 3. Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4 In freshwater ecosystems, bioconcentration and biotransformation of inorganic selenium occurs primarily in phytoplankton and periphyton, and associated biofilms. This process is the most important step towards the introduction of organic selenium compounds into local food chains. There is a large body of evidence to suggest that selenium enrichment functions can vary by up to 5 orders of magnitude for different species of planktonic algae and that biotransformation processes can differ among taxa. Similarly, previous work has shown that many bacterial genera are also capable of biotransforming and accumulating selenium using different strategies. Currently, the influence of freshwater periphyton community composition on the accumulation and subsequent food-chain transfer of selenium compounds is poorly understood. The aim of this research is to collect different periphyton community assemblages in order to address the primary question asked of this project: Does community composition matter when estimating selenium accumulation in periphyton-dominated biofilms? Field-sampled periphyton from five different lakes was exposed to aqueous selenite or selenate at concentrations of 5 or 25 µg Se/L for a period of 8 days. Selenium enrichment functions varied by up to 20-fold among the different field-collected periphyton communities and displayed saturation kinetics at environmentally relevant selenium oxyanion concentrations. The results of this work will aid in more reliable modelling of selenium transport through Northern freshwater food-webs. This will enable regulators and industry to more accurately predict the effects of selenium transfer to higher order consumers, such as fish and waterfowl.

Author / Presenter: Carolyn Martinko
Affiliation: Environment and Climate Change Canada, Biological Assessment and Standardization Section
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

The surface soil ecosystem is largely dependent on the health of its soil microbial community. At Environment and Climate Change Canada, soil microbial health is being assessed by amending a soil with a priority substance and looking for effects using a suite of microbial tests. These include organic matter (OM) decomposition, community-level physiological profiling (CLPP), and heterotrophic plate count (HPC). Currently, we are studying the impact of two rare earth elements, samarium (Sm) and praseodymium (Pr), on the soil microbial community. In individual experiments, our test substances have been added to sandy loam soil as SmCl3 or PrCl3 at different test concentrations. The soluble salt forms were used due to the high solubility of these compounds. Five concentrations were tested for both substances: 853, 1493, 2612, 4571, and 8000 mg/kg dry weight soil. A calcium chloride control was also used in each experiment to check for the possible influence of the chloride ion on our test results. Since the purpose of this research is to measure whether there are differences in soil microbial health between reference soil and the same soil spiked with SmCl3 or PrCl3, it is important to quantify the influence of the chloride component. OM decomposition, CLPP, and HPC results displayed greatly decreased microbial activity, diversity, and biomass, respectively, at the highest tested concentration of both substances compared to the reference soil. However, we suspect that chloride ions are acting as a confounding variable and may be contributing in part to the increase in toxicity to soil microorganisms at higher test concentrations of SmCl3 and PrCl3. This suspected chloride effect will be addressed in planned additional experiments.

Author / Presenter: Bruce Pauli
Affiliation: Environment and Climate Change Canada
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Several laboratory, mesocosm and field studies have evaluated the effects of glyphosate-based herbicides on frog development. However, little is known about the possible effects of glyphosate-based herbicides on frog gonadal differentiation in animals undergoing natural development in the wild. We used whole wetland manipulations to determine if exposure to an agriculturally relevant application of Roundup WeatherMax®, a herbicide formulation containing the potassium salt of glyphosate and an undisclosed surfactant, influences gonadal development of wood frog tadpoles (Lithobates sylvaticus) under natural conditions. Experimental wetlands were divided in half with an impermeable curtain so that each wetland contained a treatment and a control side. Tadpoles were placed inside in situ enclosures in each wetland half and exposed to two pulses of Roundup WeatherMax® at the predicted maximum environmental concentration (PMEC, 2.89 mg acid equivalent (a.e.)/L). Results showed that under an environmental realistic scenario, exposure to Roundup WeatherMax® does not influence gonadal differentiation in L. sylvaticus tadpoles. We conclude that detected differences on sex ratios and gonadal differentiation at the molecular level, studied by measuring mRNA levels of cyp19a1a, foxl2, cyp17 and star, are more likely due to intrinsic differences between the wetlands and the wetland sides than to exposure to Roundup WeatherMax®.

Author / Presenter: hui peng
Affiliation: University of Toronto
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

More than 2,000 natural brominated compounds were identified in our recent studies, while their biological functions in bacteria remain elusive. The present study focused on a well-known natural brominated compound, 6-OH-BDE-47, which was occasionally found to exhibit strong antibacterial potency. To identify the antibacterial mechanism of 6-OH-BDE-47, we developed a systematic and unbiased chemical proteomics assay (Target Identification by Ligand Stabilization, TILS) for target identification based on monitoring ligand-induced thermal stabilization. The TILS method was validated by identifying both known and unexpected proteins bound by diverse compounds (anticancer drugs, antibiotics). We then applied TILS to identify the bacterial target of 6-OH-BDE-47 as enoyl-acyl carrier protein reductase (FabI). Using affinity pull-down and in vitro enzymatic assays, we confirmed the potent antibacterial activity of 6-OH-BDE-47 occurs via direct binding and inhibition of FabI. Conversely, overexpression of FabI rescued the growth inhibition of Escherichia coli by 6-OH-BDE-47, validating it as the primary in vivo target. Further investigation of 18 analogues of OH-BDEs found that only natural OH-BDEs exhibited strong antibacterial potencies, and was significantly correlated with their binding affinities to FabI protein. This study uncovered the specific antibacterial activities of natural OH-BDEs, which was found to be mediated by FabI proteins. Further studies are ongoing to investigate the potential role of OH-BDEs as a novel defense strategy of marine microorganisms.

Author / Presenter: Kathleen Racher
Affiliation: Giant Mine Oversight Board
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

The Giant Mine operated within the vicinity of the Yellowknife, Northwest Territories from 1947 to 1999 when the mine owners declared bankruptcy. During the life of the gold mine, approximately 237,000 tonnes of highly toxic arsenic trioxide (As2O3) dust was generated as a by-product of the milling process and this dust is currently stored in 14 mined out chambers in the underground of the mine. The current plan for remediation of the site, as undertaken by the federal government, is to freeze the As2O3 in situ using a series of thermosyphons and freeze pipes. During the environmental assessment of the remediation project, local people accepted that freezing the dust was currently the best option for remediation but considered it to be only a temporary solution as it requires care and maintenance in perpetuity. Due to these concerns, the Giant Mine Oversight Board (GMOB) was formed in 2015 with a mandate to both oversee the government?s remediation efforts but also to develop and manage a research program for a permanent solution to the As2O3. There are several aspects of this research program that differentiates it from other types of remediation research. For example, a permanent solution will involve research into a number of different methods from remote mining methods to chemical or biological transformation of the As2O3. As well, since the arsenic chambers, once frozen, are deemed stable for at least 100 years, the research program for a permanent solution has a timeline on the order of decades. This poster will present the unique characteristics of this contaminated site and the research program including GMOB?s efforts to find innovative ways to run the program through academic or industrial partnerships.

Author / Presenter: Katherine Raes
Affiliation: University of Saskatchewan
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

The mobilization and contamination of selenium (Se) into environmental systems is of significant global concern. A variety of natural and anthropogenic sources and site-specific differences in biogeochemistry are the source for different forms and concentrations of Se in aquatic environments (eg. selenate [SeO4?²] and selenite [SeO3?²]). These inorganic forms of Se are efficiently assimilated, biotransformed, and bioaccumulated by aquatic microorganisms into organoselenium compounds, which are transferred to higher trophic levels via dietary pathways. The present study aims to quantify the trophic transfer factors of selenomethionine to a primary consumer through the biotransformation of inorganic oxyanion Se forms (selenate and selenite) by field-collected communities of microorganisms. Biofilm samplers were placed in the epilimnetic zone of uncontaminated lakes in northern Saskatchewan and allowed to accumulate natural communities of periphytic microorganisms representative of these lake habitats. DNA samples were collected from each biofilm sample for microscopic and metagenomic characterization of the biofilm communities. Samples were exposed in the laboratory to aqueous concentrations of selenite and selenate respectively, at concentrations of 0, 5 and 25 µg Se/L, and uptake and biotransformation by the biofilm to selenomethionine was quantified. The amphipod Hyalella azteca, a primary consumer characteristic of Canadian freshwater ecosystems, grazed on the Se-spiked biofilm communities with the intent to determine trophic transfer efficiencies as a function of microorganism community structure. This research will serve to assist in improving environmental risk assessment strategies for the release of Se into aquatic environments.

Author / Presenter: Joseph Salerno
Affiliation: University of Guelph
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Freshwater mussels play an integral role in aquatic ecosystems by assisting in nutrient cycling, energy transfer, habitat structure, and water quality. Populations of freshwater mussels can significantly impact water quality by filtering particulate material from the water column which can lower nutrient levels. When investigating the potential risks that waterborne contaminants pose to freshwater mussels it is important to assess ecologically relevant sub-lethal endpoints since these organisms will most likely be exposed to low concentrations of contaminants in aquatic systems. This study examined how to optimize our current method of quantifying the filtering capacity (clearance rate: CR), of mussels after exposure to contaminants in toxicity tests. CR was defined as the amount of algal cells that an individual mussel can remove from the overlying water by filtration and was determined using spectrophotometric absorbance and direct microscopic examination. Optimization of the method included consideration of the following factors: concentration of algae mixture at test initiation, duration of clearance rate assay, and statistical power. Experimental vessels were set up with juvenile (ten, approx. 6 months old) and adult (one, approx. 2.5 years old) Lampsilis siliquoidea. The optimized adult clearance rate assay was required to run for 48 hours with 2.70e7 cells/mL of algae added at test initiation and a minimum of six replicates per treatment to detect a 10% effect. The optimized juvenile clearance rate assay was required to run for 48 hours with 1.77e7 cells/mL of algae added at test initiation and a minimum of four replicates per treatment to detect a 25% effect. After a reference toxicant exposure to sodium chloride, LC50s from the optimized CR assay were compared to established mussel toxicity endpoints: survival and burial (ability of mussels to bury in clean sand). CR by direct microscopic examination was less sensitive in adults and slightly more sensitive in juveniles compared to the less labour intensive endpoints of survival and burial. No significant differences were detected between the LC50 values determined from the three endpoints.

Author / Presenter: Rick Scroggins
Affiliation: Ecotoxicology and Wildlife Health Division
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Standardized biological test methods published by Environment and Climate Change Canada (ECCC) require the performance of routine reference toxicant tests to assess the sensitivity of the test organism population over time. Over the past two decades, many standardized toxicity test methods have shifted from short-term lethality endpoints to longer-term sub-lethal endpoints such as reproduction, growth and development. In contrast, the endpoints and duration of reference toxicant tests has often remained unchanged, relying on short-term LC50 values. To address this incongruence and increase the relevance of reference tests, ECCC has decided to introduce the option of conducting reference toxicant testing using a single concentration reference toxicant ? in essence, a positive control. The option for using a positive control would implemented by adding a treatment with each definitive test, and would be run the same as a negative control (i.e., same replication, organism requirement, test vessels, etc.) except exposed to a single concentration of a known toxicant. The endpoint for a positive control would be consistent with the endpoints derived from definitive tests (e.g., weight, growth, etc.), but would involve a target effect level (e.g., 40%), pre-defined within a suitable effect range (e.g., >30 to <50% effect) by the laboratory. The application of a positive control will be described with two examples. First, we will outline the steps to be followed for incorporating a positive control in a new ECCC soil test method, the 28 day reproductive inhibition test with the oribatid mite, Oppia nitens. Second, we will review how data from a recent inter-laboratory study with leopard frogs (Lithobates pipiens) can support the selection and utility of a positive control.

Author / Presenter: Lana Shaya
Affiliation: McMaster University
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Cytochrome P450s (CYPs) are a large family of enzymes that are critical for xenobiotic and endogenous compound metabolism. The CYP3 family is extensively studied in mammals for their incredible ability to metabolize many, structurally unrelated, exogenous compounds. In mammals, CYP3 genes appears in one subfamily (A) and these are responsible for the metabolism of over 50% of pharmaceuticals. Interestingly, CYP3s in fish include four subfamilies (A, B, C, D) with function that is poorly studied but commonly thought to be similar to mammalian CYP3A. In fact, mammalian and fish CYP3As may be functionally different and appear to be regulated by different pathways. Differences in expression and regulation likely exist between the fish CYP3 subfamilies as well. Duplication of piscine CYP3 subfamilies have been hypothesized to produce genes with new functions and regulated by unique receptor pathways. This study focuses on the novel CYP3C genes in zebrafish, an important model species. Zebrafish have four CYP3C genes, CYP3C1, CYP3C2, CYP3C3 and CYP3C4, and these genes are expressed in detoxification organs including intestine and liver. In this study, zebrafish were exposed to 17?-estradiol (0.001-10?M; E2) and ?-naphathoflavone (0.001-1?M; ?NF), prototypical ligands of the estrogen receptor (ER) and the aryl hydrocarbon receptor (AhR), respectively, to determine if these receptor pathways are involved in CYP3C gene regulation. Exposure to ?NF resulted in the dose-dependant up-regulation of all CYP3Cs genes in the intestine but not in the liver. CYP3C gene expression was induced in the ovary. CYP3C induction was not observed in female intestine, ovary and testis after E2 exposure but all genes were induced in the male intestine. Finally, CYP3Cs were induced in the female liver but was down-regulated in the male liver with E2. Overall, CYP3Cs were not highly inducible by ?NF or E2 and most genes were induced between 2-4 fold over control. Yet, this data suggests that the AhR and ER may play a role in the regulation of CYP3Cs that is gender and tissue specific. The goal of this study is to provide insight on an important family of detoxification enzymes and potentially contribute to further characterizing the capacity of the commonly used model organism, the zebrafish, for metabolizing xenobiotic compounds.

Author / Presenter: Sam Sherman
Affiliation: Wilfrid Laurier University
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Potential impacts of metals in saltwater (SW) environments are significant. Globally, the largest anthropogenic releases of metals are from fossil fuel, predominantly coal and oil, combustion, mining and smelting. The binding of metal by ligands is assumed to reduce the bioavailability of metal to the biotic ligand (organism), thereby reducing toxicity in the system and this relationship can be predicted using the biotic ligand model (BLM). However, the effects of nickel (Ni) in saltwater ecosystems has not received as much research attention as freshwater (FW) ecosystems. Thus, there is a pressing need to obtain experimental data and to test models of Ni binding in order to predict, mitigate, and manage potential Ni pollution and toxic impacts. My study predicts that model ligands will reduce short term toxicity (EC50) to purple sea urchins (S. purpuratus) and that this toxicity will vary depending on the binding affinity (logKf) of the ligand. It is hypothesized that the EC50 of metal free ion (Ni2+) will be similar between model ligands if toxicity is explained by [Ni2+]. It is also hypothesized that the binding affinity of the biotic ligand can be determined using known binding affinity constants. Defined solutions of artificial seawater (ASW) containing different model ligands (i.e. ethylenediaminetetraacetic acid (EDTA), glutamic acid (GA), tryptophan (TRY), histidine (HD), and citric acid (CA)) were used for Ni toxicity and speciation tests. Total dissolved Ni concentration [NiD] of the treatments has been measured using the Graphite Furnace Atomic Absorption Spectrometer (GFAAS) and [Ni2+] has been predicted using Visual Minteq 3.1. The dose-response curves were expressed both as % abnormal development of the sea urchin embryo by [NiD] and [Ni2+] and corresponding EC50 values were determined. In the same defined solutions, Ion Exchange Technique (IET) coupled with GFAAS were performed to determine [Ni2+] and compared against Visual Minteq results in order to evaluate the feasibility and applicability of the IET method. The methods developed with model compounds can be applied to natural samples in order to determine the binding affinity and protectivity of dissolved organic matter (DOM) and Ni EC50 values. The results showed that: 1. protection of the biotic ligand occurred when model ligands were added; 2. protection increased with increased Ni binding affinity; 3. consistent with the BLM, Ni toxicity can be explained by [Ni2+]; 3. IET-GFAA is a suitable technique for determining [Ni2+] in sea water. The results of this research contribute to the development of biotic ligand-based prediction models for estimating the impacts of Ni in marine water. Funding was provided by Natural Sciences and Engineering Research Council of Canada (NSERC), VALE and NiPERA (Nickel Producers Environmental Research Association).

Author / Presenter: Ryan Stevenson
Affiliation: Hatfield Consultants
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

The target lipid model (TLM) is a relatively novel approach applicable to predicting the combined toxicity of polycyclic aromatic hydrocarbon (PAH) mixtures to aquatic organisms. It applies the critical body residue principle which proposes that once absorbed into an organism the combined toxicity exerted by multiple individual PAH compounds will be additive, with a mode of action involving non-polar narcosis. Combining the TLM with equilibrium partitioning allows individual PAH concentrations in sediment to be converted to a toxic unit; the toxic units can be summed for all PAHs in the sediment to estimate the overall toxic potential of the PAH mixture. This toxic units approach is potentially-useful as a tool for screening the toxic potential of naturally-occurring and anthropogenic PAH mixtures in aquatic sediments of the Athabasca Oil Sands Region. While the method has shown promise based on validation with data sets in the United States, the wealth of co-occurring sediment PAH and ecotoxicity data (500+ synoptic chemistry and toxicity measurements) collected since 1997 through the Regional Aquatics Monitoring Program (RAMP) and Joint Oil Sands Monitoring (JOSM) program provides an opportunity for further validation of the method, specific to conditions present in the Athabasca System. In this poster, we compare chemistry-derived toxicity predictions to corresponding laboratory-observed sediment toxicity for standard midge, oligochaete and amphipod test species. We test the prediction accuracy of two versions of the TLM (available in the literature and US EPA guidance) as well as differing equilibrium partitioning assumptions (partitioning to organic carbon vs. free-phase hydrocarbons). By examining the similarities and differences between predicted and observed toxicity it is possible to evaluate the utility of the toxic units method as a screening tool for PAH mixtures in sediments of the Athabasca system, and better understand the factors that may influence sediment toxicity in the field.

Author / Presenter: Katrina Sullivan
Affiliation: Environment and Climate Change Canada
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Under the Chemicals Management Plan (CMP), the Government of Canada is assessing and managing, where appropriate, the ecological and human health risks of substances. Building on previous work under the CMP (over 2700 substances addressed from 2006 to 2015), 1550 substances have been identified as priorities for assessment over the subsequent five years (2016-2020). Examples of the 1550 substances include a group of quaternary ammonium compounds (QACs). This poster provides a description of the QAC group, an overview of the available data, and preliminary assessment approaches for these compounds under CMP. Activities on characterizing these substances, which are representative of a wide range of QACs, may be used to inform a broader evaluation of QACs in the future.

Author / Presenter: Laura Taylor
Affiliation: University of Prince Edward Island
Student: Yes

Session: Tuesday Poster Session
Date: Monday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Aquaculture, agriculture, and the American lobster (Homarus americanus) fisheries are three economically important industries in the Atlantic regions of Canada and the United States and have great potential to interact within the marine ecosystem. A common practice in aquaculture and agriculture industries is the use of pesticides. These pesticides have the potential to interact with non-target organisms, such as the American lobster, through runoff, spray drift, and dispersal. In recent decades, lobster landings have declined in the Northumberland Strait, a body of water with surrounding agricultural industries, and recruitment of larvae has decreased in areas of the Bay of Fundy, containing nearshore salmon farms. Larval stages of H. americanus are vulnerable to both hydrophilic and hydrophobic pesticides since early larval stages reside in the pelagic zone before settling to the benthic zone. Both of the organophosphates Salmosan® (an aquaculture pesticide with the active ingredient azamethiphos) and chlorpyrifos (an agricultural pesticide) target arthropodic pest insects and have been shown to affect the survival of some larval decapod crustaceans. Azamethiphos has been shown to impact the growth and survival of H. americanus yet no data exists on the impacts of chlorpyrifos to this species. Using 3- and 48- hour acute exposures of Salmosan® and chlorpyrifos respectively, median lethal concentrations were established for stage IV American lobster. During sublethal exposures, the growth parameters intermoult period, moult inhibition, and specific growth rate were found to be significantly affected when compared to the control treatment. RNA sequencing was carried out using Illumina Hiseq technology and subsequent confirmation of the expression of genes of interest was performed via RT-qPCR. In the current study, it was determined that both organophosphates affected expression of genes encoding for stress responses and xenobiotic metabolism. Chlorpyrifos exposures additionally affected expression of hypoxia response and axonal growth related genes while azamethiphos exposure corresponded to changes in expression of genes related to oxidative stress and immunity.

Author / Presenter: LESLY TEJEDA-BENITEZ
Affiliation: UNIVERSITY OF CARTAGENA
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Pesticides are a group of compounds utilized for crop protection in agriculture, domestic application, and disease control, among others. However, their continuous application and release to aquatic environments has lead their presence in sediments, becoming a matter of concern due to their capacity of bioaccumulation and persistence. Some pesticides have been considered toxic at different levels: endocrine disrupters, cancerigen, neurotoxicant, among others. In Colombia, a country with a vast agricultural activity, the use of pesticides is generalized in many processes, including illegal crops eradication. The Magdalena River, the most important waterway in Colombia, and the main source of drinking water and fish, is sink of runoff from agriculture, and the presence of pesticides in its sediments is unknown. In this study, sediment samples were collected in 20 sites of the Magdalena River, and analyzed for 40 pesticides among organophosphorus, chlorinated, uracil, triazines, chloroacetamides, and thiocarbamates. Methanolic leachate of each sample was obtained by centrifugation-filtration, and used exposing Caenorhabditis elegans in L4 larval stage for 24 h to evaluate survival, locomotion, growth, fertility, egg-production, reproduction, and changes in the expression of stress response related genes. The most abundant pesticides in the Magdalena River sediments were atrazine (0.76 ± 0.99 ng/g), bromacil (0.74 ± 0.52 ng/g), 4,4´DDE (0.66 ± 1.38 ng/g), and chlorpyrifos (0.45 ± 0.64 ng/g). The highest concentration of these pesticides were found in samples taken in towns located in agricultural areas where oil palm growth is very intensive, and the use of pesticides is poorly controlled. All samples presented DDT/(DDE+DDD)<1, indicating historical contributions of DDT. The most of the samples showed DDD/DDE ratio < 1, suggesting aerobic conditions. Effects in survival, growth, and locomotion were observed in the samples related to industrial, gold mining and petrochemical activities. Changes in gene expression were evident for cyp-34A9, especially in the sampling site located near an oil refinery, and at the seaport, in Barranquilla City. Nematode fertility, egg-production and brood size were inhibited up to 22, 33, and 37%, respectively. There was strong and negative correlation between fertility, egg production, and brood size and the concentration of some pesticides such as dichlorvos, mevinphos, metachlor, trans-chlordane, cis-chlordane, DDE, endosulphan sulfate, famphur, and chlorpyrifos. In addition, dichlorvos correlated with the expression of gst-1 and cyp-34A9; molinate was associated with the expression of hsp-16.2. The concentration of etotrophs was related to survival. The ?,?BHC content was associated with locomotion. The presence of bromacil corresponded to survival and with expression of sod-1, cyp-34A9, and gpx-6. Fenthion and parathion were correlated to survival and locomotion. Chlorpyrifos correlated to the expression of hsp-16.2, gst-1, and cyp-34A9. Coumpafos had strong associations with hsp-16.2, gst-1 and gpx-6. In conclusion, the presence of pesticides such as chlordane, DDT-related compounds, and chlorpyrifos, among others in Magdalena River sediments is associated with survival, locomotion, reproductive toxicity, and the expression of stress response related genes on the biological model C. elegans.

Author / Presenter: LESLY TEJEDA-BENITEZ
Affiliation: UNIVERSITY OF CARTAGENA
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Nickel is a transition metal widely distributed in the environment, with several industrial applications. However, its toxicity mechanisms have been poorly studied. To assess the toxicity of nickel sales, the wild type C. elegans strain Bristol N2 was used in bioassays through different toxicity endpoints such as lethality, locomotion, growth and fertility. GFP transgene integrated with the mtl-1, sod-4 and gpx-6 genes were used to assess changes in gene expression. Escherichia coli OP50 was used as food in K agar prepared with KCl, NaCl, agar, peptone, cholesterol, CaCl2 and MgSO4. The larval age synchronized nematodes L4 and L1 were exposed to concentrations of 0.1, 1.0, 10, 100 and 1000 ?M of three nickel salts: NiCl2.6H2O, NiSO4.6H2O and Ni (NO3) 2.6H2O, respectively; and also, to mixtures of these. Medium K (52 mM NaCl and 32 mM KCl in ultrafiltered water) was used as the control and as dilution water for the preparation of the solutions. Four replicates were performed for the treatment and each experiment was done in triplicate. For the evaluation of survival, larval stage nematodes L4 were exposed for 24 h to solutions of the nickel salts. Approximately 10 ± 1 worms were used for treatment. The number of live and dead worms was then counted by visual inspection using a dissecting microscope. In order to evaluate changes in locomotion, the frequency of body curves was measured, for which the nematodes previously exposed 24 h were transferred to a K agar plate and recorded for the number of body curvatures in 20 s. Each curve of the body was counted as a change in the direction of the posterior bulb of the pharynx along the Y axis, assuming that the nematode moved along the X axis. Approximately 30 nematodes were examined per treatment. Developmental assessment was performed by measuring body length in L1-age larvae after 48 h of exposure to nickel salt solutions. E. coli OP50 was inoculated as a food source. Body length was measured by analyzing a photograph recorded by a dissecting microscope and using ImageJ software. Approximately 30 nematodes were examined per treatment. To evaluate reproduction, the size of the rearing was measured. L4 larval nematodes were previously exposed for 24 h to solutions of nickel salt. Each nematode was individually fixed on K agar plates seeded with E. coli OP50 and the number of offspring was counted in all steps after 72 h. Approximately 10 nematodes were examined per treatment. Changes in gene expression were assessed using transgenic GFP reporter strains containing mtl-1, sod-4 and gpx-6 genes. Equal aliquots of nematodes at all larval stages were plated onto non-fluorescent, 96-well U-bottom black microplates with the nickel salt solutions. The plates were incubated at 15 °C and fluorescence was recorded after 24 h using a Perkin-Elmer Victor 1420 multi-level plate reader at 485/525 nm as excitation / emission wavelengths, respectively. The K medium was used as control. Normality and homogeneity of variance were verified using the Kolmogorov-Smirnov and Bartlett tests, respectively. Significant differences were determined between the means with ANOVA. The Dunnett test was applied to compare each sample with the control. The results obtained show that the survival was dose dependent, with nickel chloride being the most toxic salt. At 1000 ?M, all salts caused the mortality of all exposed animals. Regarding the effects on locomotion, the basic motions were inhibited up to 66, 54 and 39% for 100 ?M of nickel chloride, nitrate and sulfate, respectively. In turn, body length decreased by 15.5, 19.4 and 20.1% to 100 ?M of nickel chloride, nitrate and sulfate, respectively. On the other hand, brood size was dose dependent, with 86, 84 and 80% inhibition of exposure to 100 ?M of nickel chloride, sulfate and nitrate, respectively, related to the control. Changes in gene expression showed that mtl-2 was overexpressed 2.9-fold than the control for 100 ?M of nickel sulfate. The stress response genes sod-4 and gpx-6 were overexpressed 3-fold and 3.7-fold control of nickel chloride and nickel nitrate, respectively. In conclusion, these results verify that the toxicity of nickel depends on the type of salt and the concentration of the exposure, which affects the behavior of locomotion, reproduction, growth and increased the expression of stress response related genes.

Author / Presenter: Pascal Tuarze
Affiliation: Stantec Consulting Ltd.
Student: No

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

The risk adverse effects on birds in marine and freshwater environments after an oil spill (namely, loss of feather insulation leading to decreased thermoregulatory capacity and subsequent hypothermia and mortality) can be expressed as the product of the probability of encountering a spill and the volume/thickness of that spill. This paradigm is the basis of the seminal resource for assessing the effects of spilled oil on wildlife: the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Type A Natural Resource Damage Assessment Model for Coastal and Marine Environments (NRDAM/CME). In that report, a deterministic threshold volume of 350 ml is considered a lethal dose, which translates to a threshold thickness of 10 ìm for spills with diameters larger than 230 m. Some stakeholders in the risk assessment process consider oiling to be more like a non-threshold event, with even the smallest amounts of oil related to large enough changes in metabolism to bring about mortality. What is absent from the risk assessment practice is a dynamic model for predicting thermoregulatory responses in seabirds after an oiling event. Here we present 1) data (obtained through a literature search) about key variables related to avian metabolic responses to oiling (e.g., ambient temperature (both air and water), body condition, feather structure, insulative capacity, oil type); 2) what is known about the avian oiling dose-metabolic relationship under different conditions; 3) an illustrative conceptual map of the biotic and abiotic interactions related to this relationship; and 4) results of preliminary modelling (based on points 1-3) from a collaborative effort to establish a Physiologically Based Oiling Model (PBOM) for quantifying thermoregulatory responses in seabirds after oiling. From this exercise we provide our interpretations on how to make scientifically justified risk characterizations for birds interacting with spilled oil.

Author / Presenter: Justin Vanslingerland
Affiliation: University of Guelph
Student: Yes

Session: Tuesday Poster Session
Date: Tuesday 03 October 2017
Time: 8:00 – 19:00
Location:

Abstract:

Mining activity in Canada’s subarctic region has increased significantly in recent years. Potential impacts that resource extraction might have on the ecological integrity of aquatic systems in this sensitive region, however, is poorly understood. In this study, we monitored the health of several fish species as part of a baseline study for an open pit gold mine located near Rankin Inlet, Nunavut. The mine is in advanced exploration and construction phase with operations commencing in 2019. Lake Whitefish (Coregonus clupeaformis), Arctic Grayling (Thymallus arcticus), Lake Trout (Salvelinus namaycush), and 3 and 9 spine sticklebacks (Gasterosteus aculeatus & Pungitius pungitius) were sampled from six lakes Fish between 2014 and 2016 within the current zone of exploratory activities (road building and camp construction, infrastructure development, exploration, drilling, blasting and stripping the natural cover off the land) and/or eventual impact zone once full mining operations commence (where additional impacts such as lake dewatering, blasting, water retention dykes, ore processing, and effluent discharge into tailing impoundment areas are expected). Fish measurements included total weight and length, liver and gonad weight, sex, age (otolith and weight-length frequency), gut contents, and muscle tissue for stable isotope analysis. Gut contents indicate clear resource partitioning among fish species in these small lakes with lake trout predominantly eating small fish (including sticklebacks), grayling relying on amphipods, snails and some Trichoptera and whitefish exhibiting a more generalist invertebrate diet. In sticklebacks, we also noted a high incidence (~30%) of parasitism for both the 3 and 9 spine sticklebacks. Our goal is to compare pre-and-post incidences of parasitism as a basis for evaluating stress in these ecosystems. Characterizing the fish communities in these lakes will help to develop a strong baseline against which potential post-mining operation impacts can be compared.