The effects of different diets on growth, feeding preference, and intestinal microbiota of juvenile sea cucumber Holothuria leucospilota

Abstract

Finding an efficient and cost-effective feed is of great significance for the aquaculture and restocking of sea cucumber Holothuria leucospilota. In this study, the performance of juvenile H. leucospilota which were fed with commercial formulated feed (P), was compared with those fed by six different types of algal powders Sargassum sp. (S), Ulva sp. (U), and Laminaria japonica (L)—either solely or in a 1:1 combination (S + U, S + L, U + L). Over a 56-day experiment, we found that the mixed diet of Sargassum sp. and Ulva sp. (S + U) resulted in the highest specific growth rate (4.82 ± 0.34 % d⁻¹), which was comparable to that of the commercial formulated feed (P) (4.30 ± 0.20 % d⁻¹). Isotopic mixing model analysis revealed that H. leucospilota exhibits a preferential assimilation order of Sargassum sp., Ulva sp., and L. japonica when fed mixed diets. Additionally, the intestinal microbiota of sea cucumbers had been influenced by diets, with mixed algal diets improving microbial composition. In the S + U group, which exhibited the fastest growth, the relative abundances of Pseudoruegeria, Labrenzia, Cyanobium PCC-6307, and Megasphaera at the genus level were significantly higher than those in other groups. The results of this study demonstrate that the diet mixed with Sargassum sp. and Ulva sp. is most suitable for juvenile H. leucospilota.