Marine microalgae are essential primary producers, yet their single-cell responses to environmental stressors like salinity fluctuations remain poorly understood. This project, a collaboration between the Ruđer Bošković Institute and the Toulouse Biotechnology Institute, utilizes complementary biophysical approaches—electrochemical characterization and atomic force microscopy—to analyze microalgal bio-interfaces at the nanoscale. We hypothesize that salinity stress triggers adaptive changes in surface properties, significantly impacting cell adhesion and flocculation behavior. By investigating morphological, physiological, and extracellular modifications, this research aims to reveal fundamental adaptation strategies, providing critical insights for marine ecology, biotechnology, and optimized industrial microalgal harvesting.