Temporal dynamics of bacterial communities in the water and sediments of sea cucumber (Apostichopus japonicus) culture ponds

Abstract

Bacteria communities in the aquaculture environment have been shown to greatly influence the growth of culture species. The sea cucumber (Apostichopus japonicus) is one of the most important aquaculture species in China, with numerous economic benefits. The growth and physiological characteristics of A. japonicus exhibit remarkable seasonal variation. However, current knowledge regarding the bacterial communities in A. japonicus culture ponds and their potential roles in the regulation of A. japonicus growth and physiology remain unclear. In the present study, Illumina sequencing based on the bacterial 16S rRNA gene was used to investigate the variations in bacterial communities in the surface water and sediment of A. japonicus culture ponds for a period of 1 year. The sediments exhibited a higher diversity of bacterial communities, and a higher abundance of microorganisms involved in sulfur metabolism; however, the surface water had a higher abundance of bacterial species associated with the degradation of organic matter. Furthermore, the bacterial communities in the water column showed a “3 + 1” monthly pattern and those in the sediments exhibited a seasonal succession. The higher abundances of bacteria associated with organic pollution degradation and functions associated with bio-active compound secretion were detected in water samples collected in April, August, and December. In contrast, bacteria that are considered to be food sources for A. japonicus were more abundant in pond sediments in autumn and spring. Finally, correlation analysis demonstrated that water temperature negatively regulated the sulfur cycling efficiency of bacterial communities in sediments of A. japonicus culture ponds. This study provides an important theoretical basis for the micro-ecological regulation of pond-cultured A. japonicus.