Low Temperature Reduces Byssus Adhesion of Highly Invasive Golden Mussels: Influencing Mechanisms and Antifouling...

Byssus adhesion-based biofouling by invasive mussels poses threats to freshwater ecosystems and underwater facilities. Among existing antifouling strategies, high-temperature treatment, though effective, is limited by high energy consumption and potential surface damage. Low-temperature treatment offers a promising alternative, but its mechanisms remain poorly understood. Here, we used the invasive golden mussel (Limnoperna fortunei) as a model species to investigate the mechanisms by which low temperatures (15°C and 5°C) affect byssus adhesion. Our results showed low-temperature exposures significantly reduced adhesion rates, primarily by limiting byssus production and decreasing byssus breaking force. Staining analysis observed foot gland atrophy and thickened collagen, suggesting disrupted byssal protein secretion. Additionally, reduced levels of tyrosinase and polyphenol oxidase further suggested the decreased byssus structural integrity due to disrupted byssal protein cross-linking. Individual and integrated transcriptomic and metabolomic analyses confirmed downregulations of genes/pathways for byssal protein synthesis (such as Foot protein 15, Putative foot protein-2, and the Phenylalanine, tyrosine, and tryptophan biosynthesis pathway) and upregulations of metabolites (pretyrosine and genipin) linked to protein cross-linking disruption, which collectively restricted byssal protein synthesis, precursor availability, and cross-linking processes. Notably, integrated transcriptomic and metabolomic analyses also revealed that low-temperature exposures activated survival-prioritized responses, including antioxidant, cellular stress response, immune regulation, and anti-apoptosis, reallocating energy from byssus production to stress responses and contributing to the reduced byssus adhesion. These findings advance low-temperature treatment as a strategy for controlling freshwater mussel biofouling and provide a foundation for developing targeted, environmentally sustainable antifouling approaches.