Effect of microalgae with semicontinuous harvesting on water quality and zootechnical performance of white shrimp reared in the zero water exchange system

• Three marine feed microalgae were co-cultured with shrimp in no water exchange system.
• Microalgae co-cultured with shrimp achieved water quality control.
• Microalgae co-cultured with shrimp reduced Vibrio in water and shrimp stomach and intestines.
• Microalgae co-cultured with shrimp had positive effects on shrimp productive performance.

Microalgae cannot only provide nutrients for aquatic animals but also be useful in wastewater treatment in aquaculture. Up to now, little is known on the potential biological and economic benefits of microalgae application in intensive culture mode of shrimp. To evaluate the effects of 3 marine feed microalgae in Litopenaeus vannamei culture, a 84-day experiment was performed in this study, and water quality, Vibrio counts in water and shrimp, and shrimp growth performance in cement tanks seeded with Platymonas helgolandica (T1), Chlorella vulgaris (T2) and Chaetoceros mulleri (T3) at 0.02 mg Chl-a l−1, respectively, were compared with that in tanks without microalgae (Control). At 06:00 DO in all treatment tanks was significantly higher than that in control tanks (p < 0.05). Whereas DO at 18:00 in treatment tanks was significantly higher than that in control tanks (p < 0.05). The TAN concentration was significantly higher (p < 0.05) in the control than that in the treatments. At day 42, day 56, day 70 and day 84, the NO2-N concentration mean values were significantly higher (p < 0.05) in the control, followed by T1, T2 and T3. At the end of the experiment, Water pH in the control (7.4) was significantly lower than that in the treatments (8.44, 8.53 and 8.45 respectively) (p < 0.05). Significantly lower Vibrio counts were generally observed in the treatment tanks (p < 0.05), and the counts of presumptive Vibrio in shrimp stomach and intestines were significantly higher in the control compared to that in the treatments (p < 0.05). The highest final average weight (18.04 g) was observed in T1, which was significantly higher than that in the control (p < 0.05). T1 had the highest shrimp yield (4.41 kg m−3) at harvest, and the difference was significant (p < 0.05). T1 tended to have the highest average weight gain (1.5 g week−1) and lowest feed conversion ratio. The shrimp survival was significantly higher in T1, T2 and T3 (81.50%, 79.44% and 77.69%, respectively) than in the control (p < 0.05). The present study showed that all three microalgae in no water exchange system had positive effects on water quality and shrimp productive performance. Therefore, all three species are suitable as biofilter in situ in shrimp culture system, suggesting that microalgae have a promising potential for shrimp culture with no water exchange. Further research is needed to demonstrate the harvest and the potential applications of the microalgae.