A numerical study of the Ulva prolifera biomass during the green tides in China - toward a cleaner Porphyra mariculture

The green tides caused by Ulva prolifera have become a recurrent phenomenon in Yellow Sea, China. Investigating the factors governing the biomass of green tides is important for developing management strategies. In this study, an U. prolifera growth model was combined with a hydrodynamic model. This biophysical model can reasonably reproduce the spatiotemporal variation of the green tides in 2012. Among three zones (northern, central, and southern-zones) of Porphyra mariculture region, the northern and central zones were more important in controlling the bloom intensity, and the central zone was the key area in controlling the amount of biomass landed on beaches. Due to the limitation of temperature and nutrients, an earlier or postponed facility recycling might effectively reduce the magnitude of green tides in 2012. This study provides useful information for mitigation of green tides and management of Porphyra mariculture.