Abstract：Effects of levels of nitrogen and phosphorus and their combination on uptake of nitrogen and phosphorus by sea weed Ulva pertusa and Grateloupia ramosissima were studied. The results showed that there was increase in the uptake of nitrogen and phosphorus by the sea weed with increase in N and P concentration in the media within the suitable concentrations. The uptake of NO_3-N by these two species was affected by the interactions between NO and NH; the interactions between NO and P affected the uptake of nitrogen and phosphorus by U. pertusa and the uptake of NH_4-N by Grateloupia ramosissima; the interactions between NH and P affected the uptake of phosphorus by U. pertusa. The uptake of nitrogen and phosphorus by the sea weed changed with the sea weed body weight,without significant difference.
