Chemical Exposure and Effects in West Coast Pacific Salmon

Lead Graduate Students: Bonnie Lo, Michael McKay, Kurt Guo

With widespread urbanization and industrialization increasing demand for natural resources, environmental pollution is expected to increase and the contributions of chemical pollution to wildlife declines is of grave concern.  Indeed, contaminants are considered one of the planet’s greatest threats to natural ecosystems.  To investigate and better understand the significance of contaminants on aquatic ecosystems we use early life stage salmonids as a sentinel freshwater species. Our aim is to investigate low-level, environmentally relevant contaminant effects in salmonid species, which are ecologically significant and an important food source for many Indigenous and non-Indigenous communities.  To date, ongoing studies in the Fraser River, one of the most productive salmon rivers in the world, are revealing a diverse array of chemicals downstream of human activities, yet the ecological and human health impacts are largely unknown.  Our lab-based experiments on neonicotinoids, tire degradation products and metals are revealing sub-lethal effects in salmonids at low levels not previously reported using traditional toxicity testing measures in aquatic wildlife.  We propose that more sensitive, sub-lethal measures using advances in molecular biology (i.e. omics technologies) combined with conventional health measures in aquatic species will advance aquatic toxicity testing regimes. Ultimately, the goal is to predict contaminant concentrations that can be translated to population-level effects prior to salmonid declines and other ecological and human health impacts.

Past Graduate Students: Debbra Reeves, Sarah Calbick, Ginny Leung

Microplastics in Yukon Region Waters

Lead graduate student: Sruthee Govindaraj

Microplastics (MP), defined as any plastic polymer particles <5000 µm, are quickly becoming one of the most ubiquitous forms of anthropogenic pollution due to their detection in almost every natural system on the planet. To better to understand the extent of microplastics (MP) contamination in the Yukon Territory’s surface water, food web and the main sources of MPs in the Yukon environment, we propose a comparative study of a pristine water body and water body with known sewage effluent inputs. Thus, the main objective of this research is: to compare water, air and fish gastrointestinal tract MP concentrations at a pristine lake in the Yukon and in the Yukon River upstream and downstream of sewage effluent to determine if sewage effluent or urban-adjacent sites have a higher prevalence of MPs, and the extent of atmospheric deposition and uptake of MPs within the food web. Based on the findings of this Yukon-based field study and the scientific literature surrounding MP prevalence in the environment and its toxicity, we aim to estimate the risk MPs pose to aquatic life and humans in the Yukon region.

Contaminants of Concern at the Alaksen National Wildlife Area

Lead graduate students: Michael Horton, Jeff Lam

The Alaksen NWA is located on Westham Island in the Municipality of Delta, 40 km south of Vancouver, in the Fraser River estuary. In total, the site comprises 586 ha of the protected area managed for migratory birds; 300 ha of this site is Alaksen NWA, and the remaining area is the adjacent George C. Reifel Migratory Bird Sanctuary. Land tenure for the area is divided between the federal government (approx. 53%) and the provincial government (approx. 47%). This area has been officially protected under the Canada Wildlife Act since 1973, and in 1987 the site was designated a Wetland of International Significance under the Ramsar Convention, the 9th designated Canadian Ramsar site. However, the surrounding fields are leased to farmers and used for agriculture. Therefore, examining the prevalence of contaminants from adjacent agricultural areas to estimate the risks they pose to wildlife by conducting an ecological risk assessment is warranted and is described below.

Subchronic Impacts of Copper and a Copper, Cadmium, and Zinc Mixture on the Liver and Gill Proteomes of Developing Rainbow Trout (Oncorhynchus mykiss)

Lead Graduate Student: Michael McKay

Metal pollution is a global issue caused by anthropogenic activities, most notably associated with urbanization and industry, especially metal mining. The molecular mechanisms underlying the whole organism and tissue-level adverse effects (survival, growth, development, reproduction, and tissue pathology) are not well characterized for Cu, Cd, and Zn, yet these common metal pollutants pose an increased risk as co-contaminants in fish. The objective of the present study was to examine the impacts of Cu and a Cu mixture containing Cd and Zn on the liver and gill proteomes during early growth and development of rainbow trout (Oncorhynchus mykiss). To achieve this, rainbow trout were exposed for 31 days from eyed embryos through the swim-up fry life stage to waterborne treatments of Cu only (31, 47, 70, and 104 μg/L) and a mixture of Cu (31, 47, 70, and 104 μg/L), Cd (4.1, 6.2, 9.3, and 14  μg/L), and Zn (385, 578, 867, and 1300 μg/L). Label-free LC-MS/MS was employed to evaluate differences in liver and gill protein expression (n = 8 individual tissue samples per treatment) and to identify biological pathways and processes associated with sub-chronic metal toxicity. A total of 45 liver proteins and 25 gill proteins were differentially expressed (10% FDR) in metal-exposed rainbow trout relative to unexposed controls. The patterns of protein expression and pathways associated with metal exposure were generally tissue- and treatment-specific. Overall, this study provides insights into tissue-specific molecular modes of action and identifies novel candidate biomarkers of metal exposure in an early life stage salmonid.

Salamander Sensitivity to Environmental Contaminants

Lead graduate student: blake danis

Currently, no standardized toxicity tests to assess the adverse effects of environmental contaminants on salamanders exist in Canadian regulatory regimes. To determine if salamanders are more or less sensitive to environmental contaminants commonly found in the environment, a model, native salamander (Ambystoma gracile) has been reared in the laboratory and acute and chronic toxicity testing protocols have been optimized.  Several experiments have been conducted whereby salamanders were exposed to metals and pesticides during critical early embryonic and post-embryonic developmental stages.  This research entails characterizing base-line or normal molecular and physiological states and how these change and lead to adverse effects at the whole organism level when faced with toxicant exposure.  

Toxicity of Oil Sands Process-Affected Water in Early Life Stage Wood frogs (Lithobates sylvaticus)

Lead graduate student: Katelyn Stenner

Oil sands process-affected water (OSPW) is produced by the Canadian oil sands industry during the bitumen extraction processes and is currently stored in large tailings ponds on-site. OSPW is comprised of a mixture of various organic and inorganic constituents. Naphthenic acids (NAs) are a complex mixture carboxylic acids and are suggested to be one of the primary contributors of the toxicity of OSPW1. However, the composition and toxicity of OSPW is known to vary and is influenced by its age (i.e., degree of oxidation), source, and location within tailings ponds1. Moreover, quantifying and comparing the toxicity of OSPW has been difficult to describe in the literature to date.

Biomimetic extraction via solid-phase microextraction (BE-SPME) has recently been developed as a possible cost-effective screening tool for hazard assessment of the bioavailable organic components in OSPW2. BE-SPME has the potential to determine the effectiveness of OSPW remediation efforts and to reduce toxicity of OSPW and reduce animal use. As part of a multi-year study, this experiment aims to assist in the evaluation and calibration of biomimetic extraction via solid-phase microextraction (BE-SPME) analytical technique.

To date there is a paucity of studies report sublethal and chronic toxic effects of OSPW in native aquatic wildlife. In particular, no study to date has investigated the effects of OSPW on wood frogs from embyronic stages to metamorphosis. Therefore, the objectives of this study were to: (1) explore the potential lethal and sub-lethal effects of OSPW on wood frogs by conducting a controlled laboratory embryo to metamorphosis 90 day chronic toxicity test; and, (2) use these wood frog data to calibrate BE-SPME analytical techniques for use in OSPW treatment wetlands and surrounding surface waters in the Canadain oil sands region.

Enumeration Potential of Environmental DNA for Pacific Salmon Stock Assessments

Lead Research Associate: Geoffrey Y. Su

The field of environmental DNA has advanced over the past decade, with multiple approaches available for a variety of sampling media and species. While using eDNA for the purpose of simply detecting species is becoming a routine process, the utility of eDNA to estimate species abundance is not well understood. Here, we quantify salmon environmental DNA upstream of a fish counting fence along with river velocity, and together, use these values to determine the correlation between the number of salmon passing by the fish fence daily with daily eDNA rates in water before, during and after the salmon spawning season for 4 Pacific salmonids (Chinook, sockeye, coho and pink). Throughout the spawning season approximately 182,000 salmon were counted passing through the fence, of which >98% of which were pink salmon.  Pink salmonexhibited strong correlation between human counts (effect size = 0.65, SE = 0.040; ) to eDNA rates in the present study, and also exhibited day-to day-variation and a unimodal profile rising and falling with human fish counts. However, the salmon species observed in much lower numbers exhibited a much weaker correlation with eDNA levels higher during the pre-migratory period than during the migratory period for sockeye, coho and Chinook. Thus, for salmon spawning runs with less than ~1000 adults and daily counts less than ~100, the juvenile and/or prior seasons eDNA signal appears to be indistinguishable from the adult spawning eDNA signal in our river system. However, for the large pink salmon run, eDNA rates appeared to reflect a local signal of salmon in space and time, essentially tracking these fish within days of passing through the eDNA sampling site.