Biogeochemical functions of Chlorella in coastal systems: ecological relevance, application prospects, and research gaps

Coastal ecosystems are among the most productive and socioeconomically valuable environments worldwide and play a critical role in supporting sustainable fisheries, conserving biodiversity, stabilizing shorelines, and regulating nutrient balance. However, anthropogenic activities—including urban expansion, agricultural runoff, aquaculture discharge, industrial effluents, and the release of emerging contaminants—are continuously reshaping nutrient regimes and chemical conditions in coastal zones, resulting in ecological consequences such as eutrophication, bottom-water hypoxia, contaminant accumulation, and community restructuring. Chlorella, a genus of unicellular green microalgae widely distributed in coastal and other aquatic environments, has attracted sustained attention from both academia and industry owing to its high photosynthetic efficiency, broad-spectrum nutrient assimilation capacity, pollutant tolerance and transformation potential, and well-established applications in human health, food processing, and biofuel production. Beyond its industrial value, it also plays fundamental ecological roles in coastal and other aquatic ecosystems. However, with the intensification of urban expansion, industrial emissions, and the input of emerging contaminants, anthropogenic disturbances pose potential threats to its physiological traits and ecological functions. Based on this background, this review systematically synthesizes the core biological characteristics and environmental adaptation mechanisms of Chlorella, examines its regulatory roles in coastal biogeochemical cycles, and elucidates the mechanistic pathways through which anthropogenic disturbances affect its ecological functions. It further proposes integrated strategies for coastal ecological restoration and sustainable management based on Chlorella, aiming to provide both theoretical foundations and practical guidance for the protection and sustainable development of coastal ecosystems.