This finding demonstrates that aquaculture and the flow of sewage into the bay introduced a potential eutrophication risk into this coastal ecosystem. The low nutrient loading and the absence of significant differences in the DIP concentration that we found in the water column across the study sites at high tide are most likely due to the high water circulation and the rapid nutrient uptake by submerged macrophytes. The concentrations of nutrient in the water column were generally higher at low tide than at high tide, which suggests that an instantaneous measurement of the nutrient concentrations
in seawater may lead to an inaccurate judgment of the nutrient loading status.