Abstract: In order to investigate the nutrient uptake ability of macroalga and to screen efficient biofilter to remedy coastal eutrophication, this paper studied the effects of three levels temperature and light intensity and their interactions on the nitrate uptake kinetics of nitrogen starved and replete Ulva lactuca. Under nitrogen repletion, the maximum nitrate uptake rate of U. lactuca increased with increasing light intensity. At 30 ℃, the maximum uptake rate increased with increasing light intensity, but the V_max/K_m value reached the highest at medium light intensity. The optimal temperature for the nitrate uptake by U. lactuca was 20 ℃, and the nitrate uptake rate was much higher under nitrogen starved condition than under nitrogen replete condition. The nitrate uptake rate of U. lactuca was similar at 10 ℃ and 20 ℃. At 30 ℃, U. lactuca had the highest maximum uptake rate at medium light intensity. The increase of light intensity enhanced the nitrate uptake at 10 ℃ and 20 ℃, but had less effect at 30 ℃. Nitrogen starved U. lactuca had a higher nitrate uptake rate than nitrogen replete U. lactuca. Even under nitrogen replete condition, U. lactuca could still take nitrate from the ambient environment.

Key words: RS and GIS, Landscape pattern analysis, Landscape indices, FRAGSTATS