Photosystem-Driven Resilience of Green Microalga <i>Tetraselmis chuii</i> toward Acute Nonylphenol Stress

) ratio, to protect photosynthetic core complexes. This response is accompanied by a substantial metabolic shift from heme to chlorophyll biosynthesis, enhanced production of high-energy carriers (NADPH and ATP), and increased carbon fixation to support repair processes. Multiple interconnected photoprotective strategies are employed against reactive oxygen species, including chlorophyll breakdown, coordinated upregulation of carotenoid and α-tocopherol, and photosystem II subunit S (PsbS)-dependent nonphotochemical quenching. The understanding of microalgal resilience under chemical stress provides critical implications for assessing aquatic ecosystem health, guiding microalgae-based bioremediation, and informing global risk assessments of emerging contaminants.