Plastic pollution is one of the biggest environmental challenges of the modern era, and nanoplastics – plastic particles smaller than 1 µm – are becoming an increasingly prevalent pollutant in aquatic ecosystems. The goal of the proposed project is to investigate the effects of nanoplastics on marine microalgae, photosynthetic microorganisms key to primary production that form the foundation of the marine food chain, at an elevated temperature that simulates the conditions of climate change. Experiments will involve exposing the widespread marine green microalga Dunaliella tertiolecta Butcher (Chlorophyceae) to polystyrene nanoplastics (50 nm in size) under controlled laboratory conditions, with temperature manipulation to simulate global warming conditions. The response of the microalga D. tertiolecta to the combined impact of nanoplastics and elevated temperature will be thoroughly investigated by studying the effects on growth dynamics, nanostructure, nanomechanics, photosynthesis and parameters related to oxidative stress. The results of this research will provide new knowledge about the synergistic effects of nanoplastics and climate change on microalgae in aquatic ecosystems and will contribute to the understanding of the ecological consequences of nanoplastics.