Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Geography & Environmental Studies

Faculty/School

Faculty of Arts

First Advisor

Brent Wolfe

Advisor Role

Professor

Second Advisor

Roland Hall

Advisor Role

Professor

Third Advisor

Jason Venkiteswaran

Advisor Role

Assistant Professor

Abstract

Arctic and subarctic environments are being adversely influenced by human-caused climate change across our entire planet. Canada’s northern freshwater ecosystems are influenced by a variety of environmental stressors and are particularly sensitive to climate change, since small shifts in climate have the potential to substantially alter their hydrological, limnological, and biogeochemical conditions. Some other indirect effects on northern freshwater landscapes are the expansion of vegetation as well as changes in wildlife and waterfowl populations and distribution. It is, therefore, critical to understand the observed and predicted influences of climate change and other environmental stressors on these northern freshwater environments dominant in arctic and subarctic landscapes, since they are considered productive northern “oases” and provide important habitat for wildlife and natural resources for indigenous communities.

Concerns have been increasing regarding climate change, rapidly changing lake levels, and the associated effects on aquatic ecological integrity within two of Canada’s northern lake-rich national parks, Vuntut National Park (VNP), Yukon Territory, and Wapusk National Park (WNP), Manitoba. To address these issues, Park-led monitoring programs have been established to track status and trends of lake hydrological conditions using water isotopes, yet there remains a need to translate these data into a format that can be used by Parks Canada for their reporting requirements. Here, a novel water isotope-based lake hydrological monitoring program is applied that directly encompasses Parks Canada’s long-term monitoring protocols and provides a sensitive way to detect hydrological change. Lake category (VNP - ‘snowmelt-dominated’, ‘rainfall-dominated’, or intermediate and WNP - coastal fen, interior peat plateau, or boreal spruce forest) and season-specific (spring, summer, fall) water isotope-based hydrological thresholds were used to establish the condition (‘good’, ‘fair’, ‘poor’) of Parks Canada’s hydrological ‘Ecological Integrity Measure’ for lakes within these two northern parks. Variability in the condition of VNP monitoring lakes exists between lake category (‘rainfall-dominated’, ‘snowmelt-dominated’, intermediate) as well as by season (spring, fall) from 2007 to 2015. However, rainfall-dominated lakes show the most variability in lake condition, spanning from lakes that fall entirely within the ‘good’ condition to lakes that are almost entirely in ‘fair’ to ‘poor’ conditions. In WNP, variability in lake condition exists between lake category (coastal fen, boreal spruce forest, interior peat plateau) and season (spring, summer, fall) from 2010 to 2013. However, during the spring and summer of 2014 and the entire ice-free season of 2015, these lakes improved to ‘fair’ or ‘good’ conditions, reflecting an increase in the precipitation/evaporation ratio. This research and monitoring-program development has bridged the gap between research science and Parks Canada monitoring by providing protocols and technical support to establish an effective long-term lake hydrological monitoring program for sensitive northern freshwater environments.

During the past ~40 years, WNP has experienced a rapid increase in Lesser Snow Goose (LSG) population and a corresponding expansion in the LSG-disturbed geographic region. This has raised concerns about environmental effects of their activities on WNP’s aquatic ecosystems. Previous studies have found that using standard limnological measurements (e.g., specific conductivity) combined with carbon isotope variables (δ13CDIC, δ13CPHYTOPOM, Δ13CDIC-PHYTOPOM) is informative and effectively captures differences in limnological and carbon behaviour in LSG-disturbed ponds compared to unaffected ponds. This research compiles mid-summer limnological and carbon isotope data from 45 lakes during 2015 and 2016, which span a LSG disturbance gradient (undisturbed, actively-disturbed, severely-disturbed) across a portion of WNP. In 2015, higher mid-summer values of specific conductivity, pH, TP, TKN, DIC, DOC, and δ13CPHYTOPOM paired with lower mid-summer values of δ13CDIC and Δ13CDIC-PHYTOPOM values were characteristic of severely-disturbed ponds when compared to undisturbed and actively-disturbed ponds. Results from 2016 indicate a clear LSG disturbance gradient with increasing values of specific conductivity, pH, TP, TKN, DIC, DOC, and δ13CPHYTOPOM paired with decreasing values of δ13CDIC and Δ13CDIC-PHYTOPOM, as LSG disturbance increased from undisturbed to actively-disturbed to severely-disturbed ponds. Reduced sensitivity to LSG disturbance during 2015 can be attributed to substantial rainfall that occurred during the month of July prior to and during sampling. These limnological trends can be explained by an array of processes including chemically-enhanced CO2 invasion, elevated catchment runoff of nutrients, carbon and ions, as well as enhanced aquatic productivity, which increasingly influenced the nutrient and carbon balance of ponds along a LSG disturbance gradient. A numerical synthesis of the data identified established (by La Perouse Bay), active (the landscape to the north and northwest of Thompson Point), and emerging (the inland area in the southern portion of the study region) areas of LSG disturbance. Continued monitoring of LSG disturbance within WNP is critical to understand how freshwater environments in WNP will respond to historical, active, and new LSG disturbance. The analyses and interpretations presented in this research will serve as a useful tool for Parks Canada staff to monitor aquatic ecosystem trends and status as LSG population and migration patterns continue to evolve.

Monitoring and anticipating lake hydrological and limnological change is challenging in the north due to its remoteness and the sensitivity of shallow lakes and ponds to multiple environmental stressors. Often, due to the lack of alignment and effective communication of research priorities between southern researchers and northern agencies, the short duration of funding, as well as the high turnover rates of staff and graduate students, the science and training necessary to create the foundations for agency-led monitoring is not always feasible. However, by means of substantial efforts to augment relations with Parks Canada staff, a long-term lake monitoring program within Wapusk National Park (the ‘Hydroecology Monitoring Program’) was successfully established in 2015. These efforts included instilling the significance of our research to Park’s staff and the local community of Churchill, providing the necessary training and knowledge transfer, as well as offering ongoing assistance and guidance. This monitoring program has been developed in a format that aligns with Parks Canada’s mandate, can be utilized for their reporting requirements, and is designed to focus on two major threats to aquatic ecosystems: 1) Pond Water Dynamics/Lake Hydrology monitoring and 2) Goose Aquatic Impact monitoring. Several key contributions transformed this research science into action and application. These include operationalizing agency-led monitoring (e.g., creation of training schematics and standard operating procedures), communicating monitoring results with science practitioners (e.g., scientific reports and open-access data), and communicating research with the general public (e.g., news articles, public presentations, and the Expedition Churchill interactive platform). In summary, research presented here is a contribution to the new research paradigm in northern Canada, where collaborative, interdisciplinary, and community-driven research reflects northern priorities and leads to action.

Convocation Year

2019

Convocation Season

Fall

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