The Effects of Predominantly Chemoautotrophic Versus Heterotrophic Biofloc Systems on Nitrifying Bacteria, Planktonic Microorganisms, and Growth of Penaeus vannamei, and Oreochromis niloticus in an Integrated Multitrophic Culture

The aim of this study was to evaluate the effect of predominantly chemoautotrophic and heterotrophic biofloc systems on ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and planktonic microorganisms in an integrated Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. Shrimp and tilapia were stocked at a density of 400 shrimp m−2 and 45 fish m−3, respectively. The trial consisted of two biofloc treatments, with three replicates each: chemoautotrophic and heterotrophic. The identification and quantification of the planktonic microorganisms (ciliates, flagellates, microalgae, and total bacteria) and nitrifying bacteria were carried out through direct counting and fluorescence in situ hybridization, respectively. At the end of the trial, heterotrophic treatment had resulted in higher total abundance of bacteria. The relative abundance of AOB and NOB in relation to the total abundance was less than 0.1% for both treatments. The system was dominated by flagellates in both treatment groups. The abundance of microalgae and ciliates was higher with chemoautotrophic treatment. After 43 days, the shrimp weights were higher in the chemoautotrophic group, while the final weights of the tilapia were not significantly different between the two treatments. The type of biofloc system (Chemoautotrophic vs. Heterotrophic) did not significantly alter the establishment of AOB and NOB in a Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. The two treatments proved to be equally efficient for maintaining good water quality, but the chemoautotrophic treatment resulted in better shrimp growth. Thus, our study demonstrated that chemoautotrophic biofloc is a promising approach in integrated multitrophic aquaculture.