Zn ions and Fe plaque jointly alleviate Cu toxicity in Sargassum patens C. Agardh

Excessive Cu is toxic to Sargassum patens. Understanding the biological control mechanism behind Cu uptake, including the effect of competitive behavior with other metals, such as Zn, is beneficial for expanding our knowledge of species-specific metal uptake behavior. In this study, we cultured a macroalgal species, S. patens, and exposed it to Cu and Zn to evaluate the metal uptake behavior and biological response of S. patens. Exposure to Cu and Zn under different culture conditions not only affected the uptake behavior of each metal but also influenced S. patens growth. At low concentrations, neither metal significantly affected algal growth, whereas high concentrations of Cu negatively affected the photosynthetic activity and growth rate of S. patens. The presence of Zn at equally high concentrations was observed to increase the tolerance of S. patens to Cu exposure. Fe plaque also played a role in modulating Cu exposure; its absence increased Cu accumulation and suppressed Zn accumulation, subsequently decreasing the ability of Zn to alleviate Cu toxicity, which in turn increased algal stress.