Environmental factors of rearing water and growth performance of shrimp (Penaeus vannamei) in a microalgal monoculture system

Abstract

Microalgal ecological regulation technology uses beneficial planktonic microalgae in water their physiological and ecological characteristics, and then to regulate and optimize the water ecological environment. To identify high-quality algal strains suitable for microalgal ecological regulation technology and analyse the ecological regulation mechanism of microalgae in shrimp culture, Nannochloropsis oculata and Thalassiosira sp. preliminarily were used as the research objects. A 60-day feeding trial was conducted to evaluate the effects of N. oculata and Thalassiosira sp. monocultures on the growth performance (survival rate, yield, food coefficient, and specific growth rate) of shrimp and the physicochemical factors (DO, pH, NO2−-N, NO3−-N, NH4+-N, PO43−-P, COD and EI) and biotic factors (content of Vibrio Spp., Vibrio parahaemolyticus and bacteria) of the rearing water. The results showed that different microalgae had significant effects on the growth performance of shrimp and the environmental factors of rearing water. On the one hand, among the groups, the Thalassiosira sp. group (TG) had the highest survival rate, SGR and yield. On the other hand, similar to the nitrogen and phosphorus contents, the eutrophication index was significantly lower in the N. oculata group (NG) and TG than in control group (CG). Furthermore, of the groups, TG had the lowest Vibrio parahaemolyticus content. In summary, the Thalassiosira sp. monoculture in the rearing water absorbed nitrogen and phosphorus, reduced eutrophication, regulated the water environment, inhibited the growth of V. parahaemolyticus and increased the survival and yield of shrimp. This research provides an important theoretical basis and a representative demonstration for constructing a more efficient monoculture technology for microalgae and a new model for ecologically friendly and healthy shrimp cultivation and management.