Abstract:

In order to reduce the risks and to enhance the crab yields. We threw the seaweed Gracilaria tenuistipitata into the crab pond with a semi-closed culture mode in the late cultivation period, and combined the parameters of the environmental factors and the crab yields and survival rate to check the improvement effects on water quality from the ecological aspect. It was shown that the levels of dissolved oxygen (DO) and pH had been significantly higher than those of the control pond since the tenth day and the twentieth day respectively (P<0.05), the salinity had been significantly lower than the control since the twentieth day (P<0.05), the level of ammonia-N and nitrite-N had been lower than the control from the tenth day, and the level of phosphate-P and chemical oxygen demand (COD) was always higher than the control during the whole period owe to high starting levels of the former. But on the fortieth day the difference between the phosphate-P levels of the two ponds decreased. Moreover, the crab yields and survival rate was respectively 14.30 kg and 2.23% higher than the control, as well as those of the other cultured animals. It was indicated that the seaweed G. tenuistipitata improved the water quality in the crab pond with a semi-closed culture mode, reduced the probability of environmental factors degradation and increased the crab yields and survival rate, which enable controlling and deducing crab disease outbreak being feasible. So, this culture mode may be popularized in Niutianyang Culture Zone.