Performance of shrimp recirculating aquaculture system with copper polluted water

The disease outbreaks, environmental degradation and poor management practice are the major problems to the shrimp aquaculture industry in recent years. With the developing of engineering, aeration and the high quality of artificial feeds, shrimp culture in a recirculating aquaculture system (RAS) becomes an environmentally and economically sustainable method to solve those problems. But the copper pollution has been a big problem in the coasts of China as a result of the developing of industry, and the shrimp cultures also use copper sulfate frequently to eradicate algae during Litopenaeus vannamei culturing. An experiment was conducted for intensive culture of shrimp (L. vannamei) in RAS for a period of three months to concentrate on the performance of the biofilter and the food safety under the copper polluted water (0.3 mg/L). The results indicated that there was no significant difference in the removal rate on COD, NH4-N and NO2-N and the number of heterotrophic bacteria, ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in the biofilm as the Cu2+ concentration decreased to (0.089±0.012) mg/L at the harvest. No significant difference was found between treatments concerning the feed conversion ratio (FCR), the mortality rate and the yield. The accumulated concentration of Cu2+ in the shrimp at last was (29.36±4.06) mg/kg and (42.91±6.10) mg/kg in the control and treated RAS respectively, but it was in the range of national security standards of the green food and pollution-free agriculture products. The study suggests that the RAS can work well and supply safety food shrimp under 0.3 mg/L copper pollution in three month culturing period.