Assessing landscape influences on the base of the aquatic food web across the North Saskatchewan River basin

  • Author / Creator
    Lightbown, Jillian N
  • Anthropogenic activities are forcing a shift in landscape types and climate regimes with concomitant effects on runoff draining into regional rivers and downstream water quality. Stream microbial communities at the base of aquatic food webs play an important role in overall ecosystem health, yet there has been limited work integrating the effects of landscape type and water quality on their community structure. Here we investigate these relationships across the North Saskatchewan River basin, an expansive watershed in Alberta (Canada), spanning forested, industrial, urban, and agricultural landscapes, and the primary drinking water source for a major city and 65 other communities. Over summer 2020 and 2021, samples for 48 water chemistry parameters (e.g., nutrients, ions, metals, oxygen isotopes), organic carbon character, and microbial community composition were collected from 78 tributaries across the North Saskatchewan River basin land use and land cover gradient. We found significant differences in water chemistry with lower nutrient and ion concentrations in alpine and forested regions compared to agricultural lands and city centers. Organic matter character across the basin was largely driven by differences in allochthonous input, where composition across the varying landscapes aligned with the changing soil type across the basin. Microbial community structure was also distinct across the basin, with the alpine sites containing the highest number of unique species (10,521) and the urban and agricultural sites being the most similar. Additionally, a universal core community was present across all sites (6-98%), composing the lowest relative abundance in the alpine sites, and the highest in the foothills which we propose to be a product of soil inoculation, as foothills sites have both the presence of well-developed soils, rolling topography, and high precipitation that would facilitate these inoculation events. Our findings highlight the importance of landscape influences in determining water chemistry, organic matter, and microbial community composition across the North Saskatchewan River basin. These results imply a shift in stream microbial communities as landscape types and climate regimes shift, with a possible decrease in microbial diversity as landscapes become more connected to the terrestrial environment.

  • Subjects / Keywords
  • Graduation date
    Spring 2024
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.