Slave River and Delta, Northwest Territories, Canada

Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers where winter is the dominant season. A Geomorphic Response Unit (GRU) approach was used to select hydraulically-diverse sampling sites across a northern test-case system, the Slave River and Delta, NT, Canada. Our data demonstrate that whether contaminated or not, under-ice bed sediment can represent a "worst case" scenario in terms of trace element concentrations and exposure to sediment-associated organisms in northern fluvial systems.

Project outputs include:

Doig  L.E., Carr M.K., Meissner A.G.N., Jardine T.D., Jones P.D., Bharadwaj L., Lindenschmidt K-E. 2017. Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment. Environmental Toxicology and Chemistry. DOI: 10.1002/etc.3886

Baldwin C., Bradford L., Carr M.K.,   Doig  L.E., Jardine T.D., Jones P.D., Bharadwaj L., Lindenschmidt K-E. 2017. Ecological patterns of fish distribution in the Slave River Delta region, Northwest Territories, Canada, as relayed by Traditional Knowledge and Western science. International Journal of Water Resources Development: http://dx.doi.org/10.1080/07900627.2017.1298516

Carr M.K., Jardine T.D.,   Doig  L.E., Jones P.D., Bharadwaj L., Tendler B., Chételat J., Cott P., Lindenschmidt K-E. 2017. Stable sulfur isotopes identify habitat-specific 
foraging and mercury exposure in a highly mobile fish community. Science of the Total Environment. http://dx.doi.org/10.1016/j.scitotenv.2017.02.013

The Slave Watershed Environmental Effects Program

University of Saskatchewan SWEEP team members include Drs. Paul Jones, Lalita Bharadwaj, Karl-Erich Lindenschmidt, and Tim Jardine. Funding for this project was provided by the   Canadian Water Network.

The Slave Watershed Environmental Effects Program (SWEEP) was created to help answer questions posed by the   Slave River and Delta Partnership (SRDP): Are the fish and wildlife safe to eat? Is the water safe to drink? Is the ecosystem healthy? Local and Aboriginal communities had noticed changes in the Slave River and Delta, NT, Canada and wanted to work with scientists and government agencies to create and implement a cumulative effects monitoring framework that brought together traditional environmental knowledge (TEK) and Western Science (WS). SWEEP will provide insights on how upstream developments and climate change affect both river resources and the lifestyles of the people who depend on those resources.

TEK and WS indicators were identified using a “two-eyed seeing” approach and included 41 different indicators of water quantity and quality, ice safety, fish and wildlife health, lifestyle changes and community ethics. A framework was developed to guide environmental monitoring programs with communities undergoing environmental changes. Many indicators in the monitoring program were measured by trained community members. The monitoring program results were blended in a Bayesian Belief Network (BBN) model, which was designed to balance TEK and WS indicators.

Project outputs include:

Mantyka-Pringle C.S., Jardine T.D., Bradford L., Bharadwaj L., Kythreotis A.P., Fresque-Baxter J., Kelly E., Somers G.,   Doig  L.E., Jones P.D., Lindenschmidt K-E., the Slave River and Delta Partnership. 2017. Bridging science and traditional knowledge to assess cumulative impacts of stressors on ecosystem health. Environment International 102, 125–137: http://dx.doi.org/10.1016/j.envint.2017.02.008

A video compilation of personal perspectives held by Elders and local people about the changes they witnessed in the Slave River and Delta across their lifetime.

A major source of uncertainty in predicting selenium (Se) distribution in aquatic food webs lies in the enrichment factor (EF), the ratio of Se bioconcentration in primary producers and microorganisms relative to the concentration of Se in the surrounding water. It has been well demonstrated that EFs can vary dramatically among individual algal taxa, but data are lacking regarding the influence of periphyton community composition on EFs for a given geochemical form of Se. Therefore, the goal of this study was to determine if the periphyton assemblage composition influences the uptake of waterborne Se (as selenite) and subsequent Se transfer to a model macroinvertebrate primary consumer. The bacterial and algal members of the periphyton community were characterized by targeted metagenomic analyses to assess differences among the different biofilms and possible taxonomic associations with either Se accumulation in biofilm or a grazing freshwater snail (Stagnicola elodes).

Project outputs include:

Friesen V., Doig L.E., Markwart B.E., Haakensen M., Tissier E., Liber K. 2017. Genetic characterization of periphyton communities associated with selenium bioconcentration and trophic transfer in a simple food chain. Environmental Science & Technology, DOI: 10.1021/acs.est.7b01001

The South Saskatchewan River was dammed in 1967 to form Lake Diefenbaker. In addition to providing water for recreation, aquaculture, hydroelectric power generation, crop irrigation and potash mining, Lake Diefenbaker indirectly supplies potable water to more than 45% of Saskatchewan's population. Although a source of good quality water, algal blooms in Lake Diefenbaker are periodically noted by area residents and these anecdotal observations suggested that the frequency and severity of algal blooms was increasing. Unfortunately, environmental data were too limited to assess any such trends.  In addition, good long-term water quality monitoring data (beginning in the mid 1990s) were only available for one arm of the reservoir. Given that Lake Diefenbaker is long, narrow and spatially variable, there was uncertainty regarding how well these data characterized water quality trends across the broader reservoir. Paleolimnological techniques (sediment core analyses) were therefore used to reconstruct both spatial and temporal environmental trends in Lake Diefenbaker. The various physicochemical and biological lines of investigation included:

• Particle size distribution (changes to sand, silt and clay content)
• Stable isotopes (C, N and S)
• Total organic carbon, total nitrogen
• Fecal sterols
• Particulate reactive silica
• Total phosphorus and phosphorus geochemistry
• Subfossil remains of algae (pigments, diatom frustules)
• Subfossil remains of benthic invertebrates (chironomid [midge] larvae)
• DNA preserved in the sediment profile (paleometagenomics)

This research was funded through the Global Institute for Water Security.

Project outputs include:

Doig, L.E., North R.L., Hudson J.J., Hewlett C., K.-E. Lindenschmidt and K. Liber. 2016. Phosphorus release from sediments in a river-valley reservoir in the northern Great Plains of North America. Hydrobiologia DOI 10.1007/s10750-016-2977-2

Lucas, B.T., Liber, K., Doig, L.E. 2015. Spatial and temporal trends in reservoir physicochemistry and phosphorus speciation within Lake Diefenbaker, a Great Plains reservoir, as inferred from depositional sediments. Journal of Great Lakes Research 41(Suppl. 2), 67‒80.

Lucas, B.T., Liber, K., Doig, L.E. 2015. Reconstructing diatom and chironomid assemblages to infer environmental spatiotemporal trends within Lake Diefenbaker, a narrow river valley reservoir on the Canadian Prairies. Journal of Great Lakes Research 41(Suppl. 2), 45‒55.

Tse, T.J., Doig, L.E., Leavitt, P.R., Quiñones-Rivera, Z.J., Codling, G., Lucas, B.T., Liber, K., Giesy, J.P., Wheater, H., Jones, P.D. 2015. Long-term spatial trends in sedimentary algal pigments in a narrow river-valley reservoir, Lake Diefenbaker. Journal of Great Lakes Research 41(Suppl. 2), 56‒66.

North, R.L., Davies, J-M., Doig, L.E., Lindenschmidt K-E., Hudson J.J. 2015. Lake Diefenbaker: The prairie jewel. Journal of Great Lakes Research 41(Suppl. 2), 1‒7.

North, R.L., Johansson, J., Vandergucht, D., Doig, L.E., Liber, K., Lindenschmidt, E., Baulch, H., Hudson, J.J., 2015. Evidence for internal phosphorus loading in a large prairie reservoir (Lake Diefenbaker). Journal of Great Lakes Research. Journal of Great Lakes Research 41(Suppl. 2), 91‒99.

Maavara, T., Hood, J.L.A., North, R.L., Doig, L.E., Parsons, C.T, Johansson, J., Liber, K., Hudson, J.J., Lucas, B.T., Vandergucht, D.M., Van Cappellen, P. 2015. Reactive silicon dynamics in a large prairie reservoir (Lake Diefenbaker, Saskatchewan). Journal of Great Lakes Research. Journal of Great Lakes Research 41(Suppl. 2), 100‒109.

As a result of long-term mining and smelting activities (ore processing commenced in 1930), the sediments of Ross Lake (Flin Flon, Manitoba, Canada) are highly contaminated with trace metals. Over a similar period, Ross Lake also received municipal effluent from the surrounding community. Although the yearly contaminant loads to this small northern lake were historically substantial, little information is available regarding the associated ecological impacts. An investigation was therefore undertaken to reconstruct the ecotoxicological history of Ross Lake. Cores of sediment were extracted in the summer of 2009 from the southern basin of Ross Lake. These cores were analyzed for various physicochemical and radiometric variables and sub-fossil diatom, chironomid, chaoborid, and cladoceran remains. Overall, improvements to the management of both metallurgical and municipal effluent are reflected in the physicochemical sediment record; nevertheless, the ecology of Ross Lake remains impaired and shows minimal signs of returning to a pre-industrial state.

Project outputs include:

Doig, L.E., Schiffer S.T., Liber K.  Reconstructing the ecological impacts of eight decades of mining, metallurgical, and municipal activities on a small boreal lake in northern Canada. Integrated Environmental Assessment and Management  11, 490–501.

Tse, T.J., Codling, G., Jones, P.D., Thoms, K., Liber, K., Giesy, J.P., Wheater, H., Doig, L.E. 2014. Reconstructing long-term trends in municipal sewage discharge into a small lake in northern Manitoba, Canada. Chemosphere 103, 299–305.

Elemental selenium (Se) is generally considered to be biologically inert due to its insolubility. It is also a common form of Se in sediment near uranium milling and mining operations in northern Saskatchewan, Canada. Nano-sized particles of many materials exhibit different properties compared with their bulk phases, in some cases posing health and ecological risks. We investigated the bioavailability and toxicity of Se nanoparticles (SeNPs) by 10-day waterborne and dietary exposures to larvae of Chironomus dilutus, a common benthic invertebrate. For comparison, larvae were also exposed to waterborne selenite and to dietary selenomethionine as selenized algae. Larval Se accumulation was evaluated using graphite furnace atomic absorption spectroscopy or inductively coupled plasma mass spectroscopy for total Se and X-ray absorption spectroscopy for Se chemical speciation. Nanoparticulate Se was bioavailable, at high concentrations inhibiting larval growth in both waterborne and dietary exposures; larvae predominantly accumulated selenomethionine-like species regardless of uptake route or Se form. Overall, our findings suggest little risk of direct SeNP toxicity to benthic invertebrates in Se-contaminated sediments in northern Saskatchewan. Nevertheless, elemental Se in sediments may be biologically available and may contribute to the risk of Se toxicity to egg-laying vertebrates (fish and piscivorous birds), directly or indirectly in Se-contaminated aquatic systems. Therefore, it may be necessary to include elemental Se as a source of potential exposure in ecological risk assessments.

This work was performed in collaboration with Drs. Mercedes Gallego-Gallegos and Ingrid Pickering (Canada Research Chair in Molecular Environmental Science).

Project outputs include:

Gallego-Gallegos M., Doig L.E., Tse J.J., Pickering I.J., Liber K. 2013. Bioavailability, toxicity and biotransformation of selenium in midge (Chironomus dilutus) larvae exposed via water or diet to elemental selenium particles, selenite or selenized algae. Environmental Science and Technology 47:584-92.

Information archived in lake sediments can shed light on the environmental effects of long-term mining, municipal, and agricultural activities. However, observed changes to physical or biological proxies need to be interpreted against the backdrop of natural long-term environmental cycles (which may not be very cyclical), the natural aging of lakes (i.e., lake ontogeny), and changes to climate (natural and man-made). Briefly, we have extracted a core of sediment from a small boreal lake and are currently analyzing physicochemical variables, environmental DNA (eDNA), pollen and invertebrate remains to infer climate-land-water interactions over the past 8.4 thousand years. In additional to inferring past trends, this research will shed light on the likely response of the Boreal forest and associated water resources to future changes in regional climate.