Open Collections

Klasios, Natasha

University of British Columbia

Plastic pollution has emerged as a widespread environmental issue, and microplastics, defined as plastic particles < 5 mm in size, have been found to contaminate aquatic ecosystems globally. Microplastics are a diverse suite of contaminants with variable physicochemical characteristics, which can affect their fate and effects. Microplastics have demonstrated potential to adversely affect organisms that encounter them, but some studies have not found significant effects on organisms. To improve our understanding of the true ecological impacts of microplastics, this dissertation collected data on the quantities and types of microplastics in temperate freshwater lakes in British Columbia and then used these data to inform the experimental designs of two studies which investigated the impacts of microplastics on a whole zooplankton community and on individual zooplankton. I investigated possible indirect effects of microplastic pollution in the community exposure experiment, and in the individual exposure experiment, temperature was incorporated as an additional stressor, as freshwater environments face multiple stressors simultaneously. Additionally, previous research has demonstrated the toxicity of certain contaminants can worsen with increasing temperature. By using data collected in the field to inform our experimental designs, my experiments were environmentally relevant and representative of exposure scenarios occurring in nature. Polyester fibers, likely from textiles, were found to be widespread across lakes, irrespective of the lakes’ proximity to urbanization. Due to their ubiquity, I used polyester fibers in my experiments. In the 12-week exposure experiment conducted in large, outdoor mesocosms, I found naturally occurring zooplankton communities were not affected in composition or abundance by the microplastics at environmentally relevant concentrations. In the individual zooplankton experiment, I found warmer temperatures did exacerbate the adverse effects observed, predominantly decreased survival, but this was only observed at the highest tested concentration. This work highlights the importance of incorporating environmental relevance into experiments, as my findings contrast with previous studies which utilized unrealistic or unrepresentative microplastic exposure scenarios. By incorporating realistic exposure scenarios with additional stressors, such as temperature, this work advances the field’s understanding of the true hazards of microplastic pollution in this era of global change.

Text

2025-04-24

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90750

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/