Abstract: Seaweed aquaculture is a cost-efficient and environmental-friendly way for marine eutrophication bioremediation. However, water flow is often a limit factor to seaweed growth. The results showed that for Sargassum fusiforme, the maximum of specific growth rate was (4.34 ± 0.11) %·d^-1 at a water exchange rate of 200 vol·d^-1, but for Ulva pertusa, the maximum would reach (6.31 ± 1.42) %·d^-1 or (8.00 ± 0.79) %·d^-1 at a water exchange rate of 100 vol·d^-1 and the medium or high nutrient concentration respectively. The growth rates of both species depended on application scenarios, and U. pertusa was more tolerant to highly eutrophic environment. The concentrations of all the compounds in U. pertusa also differed significantly between the scenarios, while only the soluble protein in S. fusiforme showed significant change. Enhanced water flow changed the growth of U. pertusa and soluble carbohydrate of S. fusiforme significantly. Land-based experiment indicated that the specific growth rate of S. fusiforme increased by 80% and 14% at medium and high water exchange velocities, while 41.3% and 33.3% for U.pertusa respectively, comparing with that of low water exchange velocity.

Key words: water flow, seaweed, pigment, growth rate, nitrogen rich compound