Abstract:The distribution and composition of dissolved nutrients in Zhangzi Island maricultural areas were discussed based on the data collected in March,May,July and October,2005．The results showed that because of large current velocity,the horizontal distribution of nitrogen and phosphorous were symmetrical and there were no obvious stratification between surface and bottom water(except in July).The nutrient level of DIN and PO3-4 in the surveyed areas belong to oligothrophic state.Nutrient limitations were assessed according to the ratio of Nitrogen/Phosphorus(N/P) and the concentration threshold,results showed that the limiting nutrients may change with seasons.There was high potential for phosphorous limitation of the photosynthesis of phytoplankton in July and nitrogen limitation in March and May.Though this survey revealed that there was little effect or impact of mariculture on the environment,the nutrients structure had change somewhat.For example, in March, May and July, DIN were the major component of ammonia the bottom water,and the relatively low concentrations of chlorophyll usually found at the extensive bottom culture areas may all reflect the activity of mariculture,which needs further study in the future.
