Abstract:A series of experiments were conducted to investigate the effects of nutrient supplement on nitrogen uptake and growth of macroalgae,including Gracilaria asiatica, G. chouae, Grateloupia filicina,Sargassum thunbergii, and S.pallidum. It was found that nitrate absorption of these macroalgae was obvious within certain temperature range.With the rise of temperature, the nitrite uptake rate demonstrated an increasing trend.At 15℃, G.asiatica and G.chouae exhibited a maximal uptake rate of 0.507±0.136 μmol/g•h and 0.448±0.095μmol/g•h, respectively. At 20℃, G.filicina and S.thunbergii exhibited a maximal uptake rate of 0.614±0.033μmol/g•h and 0.289±0.019μmol/g•h. At 25℃, S.pallidum exhibited a maximal uptake rate of 0.748 ±0.015μmol/g•h. These findings indicated that S. pallidum is more efficient than the other species in removing nitrogen. Temperature had a significant impact on macroalgae growth, and at 20℃,the highest growth rate in wet weight occurred in most macroalgae, especially G.chouae, reaching 4.79±0.45%/d.
