A new integrated multi-trophic aquaculture system consisting of Styela clava, microalgae, and Stichopus japonicus

Abstract

The possibility of the integrated multi-trophic aquaculture (IMTA) model consisting of Styela clava, microalgae, and Stichopus japonicus was examined in this research, in which microalgae could remove dissolvable nutrients produced by S. clava and S. japonicus to maintain the dissolvable nutrients at a lower level, and provide sufficient dissolved oxygen in the water body through photosynthesis at the same time. S. clava helped accumulate organic matter in the sediments, and the content of total organic carbon (TOC) in the sediments was significantly higher in the groups of S. clava than that in the control without ascidian. S. japonicus were able to effectively remove the particulate organic carbon and nitrogen from the sediments, and hence an obvious decrease in TOC and total nitrogen on the surface sediments. It was also found that the reproduction of bacteria on the surface sediments attributed to the biological interference of S. japonicus. It is concluded from our experiments that the IMTA system of microalgae–S. clava–S. japonicus does not have organic matter accumulated in the sediments, or the dissolved organic matter polluted, which indicates that this IMTA model is not only an aquaculture system, but also a system purifying N and P in the water body.