Microplastics are a global contaminant of concern that present a challenging area of research as they are both a solid plastic and contain a suite of chemical additives. Recent reviews have identified substantial gaps regarding the effects of microplastics on freshwater aquatic food webs, which include a lack of experimentation on higher levels of biological organization (e.g. community- and ecosystem-level). In addition to microplastics, many freshwater systems in Canada are under stress from surrounding land use. These stressors and disturbances result in the taxonomic and functional homogenization of biological communities, which may have a synergistic effect with microplastic pollution. Phytoplankton are an essential component of freshwater ecosystems and are sensitive to environmental perturbations. As such, stressors such as nutrient addition can alter the composition of freshwater phytoplankton communities. Courtney's research will test the response of diverse phytoplankton communities and simplified phytoplankton communities to better understand how biotic complexity modulates the effects of microplastics in freshwater aquatic ecosystems.