An investigation of the space distribution of Ulva microscopic propagules and ship-based experiment of mitigation using modified clay

Previous studies suggested that the removal of Ulva microscopic propagules (UMP) from cradle water might restrict the formation and expansion of green tides in the Yellow Sea, China. In this study, the distribution characteristics of UMP in the southern Yellow Sea was investigated, and then a flocculation experiment of UMP using modified clay (MC) was conducted at a selected station of the research cruise. The results indicated that the distribution of green algae thalli is one of the main factors that directly influence UMP distribution. UMP density was strongly negatively correlated with the distance between the sampling station and the centre of the area containing floating Ulva (r = − 0.618***, n = 83). > 80% of the UMP was removed from the water column after MC application at a concentration of 0.1 g/L, and MC applied at a concentration of 0.5 g/L reduced the germination rate to 0.3%.