Effects of increased CO2 and temperature on the physiological characteristics of the golden tide blooming macroalgae Sargassum horneri in the Yellow Sea, China.

The golden tide, caused by the brown algae Sargassum horneri, exerts severe influences on the Pyropia aquaculture of Jiangsu coast, China. To study the outbreak of the golden tide in response to increasing greenhouse gas emissions, S. horneri was cultured under four conditions: ambient condition (10 °C, 400 µatm), elevated temperature condition (14 °C, 400 µatm), elevated CO2 level (10 °C, 1000 µatm), and potential greenhouse condition (14 °C, 1000 µatm). The growth, photosynthetic performances, and inorganic carbon affinity of S. horneri were studied. The results showed that elevated temperature exerted a more pronounced positive influence on S. horneri growth, photosynthesis, and carbon assimilation than CO2 enrichment. The growth of S. horneri was significantly improved by moderately elevated temperatures, especially under concurrently elevated CO2 levels. This suggests that the greenhouse effect will benefit growth and carbon sequestration of S. horneri, which may enhance the frequency and scale of golden tides.