Comparative study of water environment variation in the industrial aquaculture system of sea cucumber Apostichopus japonicus

Abstract

This study investigated the microbial community, water quality, bacterial densities and growth performance in the industrial aquaculture system of sea cucumber Apostichopus japonicus without water exchange. Six treatments were set including, C (control treatment without sea cucumber culturing), S (small individual treatment), B (big individual treatment), Sd (small individual treatment with high density), Ss (small individual treatment adding carbohydrate source) and Sb (small individual treatment adding effective microorganisms). A total of 27916–32236 optimized reads and 564–742 operational taxonomic units (OTUs) were obtained from each samples. The phylum Proteobacteria, Actinobacteria, Bacteroidetes and Cyanobacteria predominated, representing 69.01–97.21% of the bacterial communities in the water samples. Cluster analysis and principal component analysis (PCA) showed that higher similarity was observed among S, Sd, Ss and Sb. The densities of TB and Vibrio in Ss were significantly higher than those in the other culture treatments after the 7th day. The concentrations of NH4-N, NO2-N, NO3-N and PO4-P in Ss and Sb were relatively lower than the other treatments. Conclusively, no deterioration was found in the water environment parameters during the 21-day culture period without water exchange, indicating that low-level water exchange protocol may be applied to the industrial aquaculture system. Based on the effects of different operations on culture system, industrial aquaculture is proved to be a viable way to rear sea cucumber.