Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Biology

Program Name/Specialization

Integrative Biology

Faculty/School

Faculty of Science

First Advisor

Derek Gray

Advisor Role

Supervisor

Abstract

The Canadian Arctic has been warming at an unprecedented rate, causing significant changes to the environment. At the same time, continued development in the north has increased the demand for gravel extraction used to construct and maintain infrastructure such as highways. The development of roadways and gradual loss of permafrost in Canada’s north has led to changes in water quality, including increased calcium, conductivity, and nutrients. In addition, gravel extraction has led to the formation of artificial gravel pit lakes. Research has yet to determine how physical and chemical changes associated with development and permafrost thaw might impact zooplankton, and no studies have been conducted to examine the water quality of the region’s gravel pit lakes, or the diversity of biota living within them.

To examine how water quality and invertebrate communities differed between natural and gravel pit lakes, I collected baseline water chemistry data, bathymetry, and zooplankton samples from 15 natural and 6 gravel pit lakes along the Dempster Highway between Fort McPherson and Inuvik. In comparison to natural lakes, gravel pit lakes were deeper, clearer, and significantly lower in nutrients. Despite these differences, pelagic zooplankton did not differ significantly between lake types, suggesting that gravel pit lakes offer quality habitat for local invertebrate species.

To examine how zooplankton respond to water quality changes caused by permafrost thaw, I surveyed additional lakes between Inuvik and Tuktoyaktuk, increasing the size of my dataset to 37 lakes. I then used my dataset to develop models used to predict how changes in water quality could affect zooplankton. My models showed that zooplankton abundance, evenness and diversity were related to conductivity, turbidity, calcium, and nutrient levels, and that water quality changes could lead to a significant increase in zooplankton abundance (1.6-3.6-fold) but decreases in evenness (1.1-1.4-fold) and diversity (1.2-1.7-fold). The magnitude of these changes raises concerns about cascading effects potentially influencing other members of the food web, such as fish.

Taken together, my results suggest that while some stressors may have unexpected positive benefits for northern biodiversity (creation of gravel pit lakes), others may negatively influence diversity in small Arctic lakes (permafrost thaw).

Convocation Year

2019

Convocation Season

Fall

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