Preliminary studies on density changes of Gracilarla tenuistipitata var. liui used for the purification of shrimp effluent

Under laboratory conditions, shrimp aquaculture effluent was treated with six densities of Gracilarla tenuistipitata var. liui (0，10，20，25，30 and 35 gL-1） respectively for comparing the efficiency of the degradation of NH4+，NO2-，NO3-，PO43- in 24 h. The obtained results showed that all of the five densities used had obvious positive effects on the degradation of NH4+ and PO43-（P0.05）. The optimal density of Gracilarla tenuistipitata var.liui for degradation was 30 gL-1, which can result in 69.69% and 92.62% of relative rates of degradation for NH4+ and PO43-，respectively.