| Abstract: | We present results on the effect of modified clay on cyst formation of Scrippsiella trochoidea in harmful algal bloom(HAB).Modified clay(in concentration of 0,0.1,0.5,and 1.0 g/L) were added to cultures,and observations were made on cysts of 5.trochoidea under controlled laboratory conditions.Results indicate that the removal rate of algal cells reached 97.7%at the clay concentration of 1.0 g/L.The cyst formation rate increased from 4.6%to 24.6%when the concentration of clay was increased from 0to 1.0 g/L.Two cyst metamorphs were observed:spinal calcareous cysts and smooth noncalcareous ones.The proportion of the spinal cysts decreased from 76.9%to 24.1%when clay concentration increased from0 to 1.0 g/L.In addition,modified clay affected cyst germination.The germination rate decreased with the increases in the clay concentrations.Non-calcareous cysts had a lower germination rate with a longer germination time.We conclude that modified clay could depress algal cell multiplication and promote formation of temporal cysts of 5.trochoidea,which may help in controlling HAB outbreaks. |
