Experiments with Lamnaria japonica were conducted in Meidao Bay and Pier Bay,Qingdao,China,Nitrogen-starved plants were fertilized intermittently with 7.1 mM NH4-N solution for 1 hour at 3 day intervals, after which chlorophyll a, fucoxanthin, chlorophyll c and B-carotene contents were analyzed. Photosynthetic and growth rates of plants and nitrogen content of seawater were determined. Photosynthetic and growth rates of the nitrogen-enriched plants were higher than those of the controls, and their contents of chlorophyll a, fucoxanthin, chlorophyll c and B-carotene were 1.65,0.67,0.33 and 0.06 mg . dm-2 respectively, or 2.46,2.03,1.86 and 1.81 times those of the controls. The ratio of fiicoxanthin to chlorophyll a in nitrogen-enriched plants was lower than that of the controls. Normal growth rate of the plants (2 cm.day-1 in length)were reached when the chlorophyll a content exceeded 0.1 mg.g-1 fresh wt., indicating that chlorophyll a content can serve as an indicator of normal growth.Experimental resul Experiments with Lamnaria japonica were conducted in Meidao Bay and Pier Bay, Qingdao, China, Nitrogen-starved plants were fertilized intermittently with 7.1 mM NH4-N solution for 1 hour at 3 day intervals, after which chlorophyll a, fucoxanthin, chlorophyll c and B Photosynthetic and growth rates of the nitrogen-enriched plants were higher than those of the controls, and their contents of chlorophyll a, fucoxanthin, chlorophyll c and B-carotene were 1.65, 0.67, 0.33 and 0.06 mg. Dm-2 respectively, or 2.46, 2.03, 1.86 and 1.81 times those of the controls. The ratio of fiicoxanthin to chlorophyll a in nitrogen- enriched plants was lower than that of the controls. Normal growth rate of the plants (2 cm.day-1 in length) were reached when the chlorophyll a content exceeded 0.1 mg.g-1 fresh wt., indicates that chlorophyll a content can serve as an indicator of normal growth. Experimental resul