THE DYNAMICS OF BACTERIOPLANKTON COMMUNITIES ASSOCIATED WITH MACROBRACHIUM ROSENBERGII ACROSS WHOLE LARVAL DEVELOPMENT: SUCCESSIONAL PROCESSES, ENVIRONMENTAL DRIVERS, AND DEVELOPMENTAL BIOMARKERS

A suitable micro-ecological condition is of great significance to the Macrobrachium rosenbergii larval development and health, however, the fine-scale temporal dynamics and assembly mechanisms of bacterioplankton of prawn larval nursery are unexplored. We investigated dynamic succession, environmental drivers, biomarkers and co-occurrence networks of bacterial communities across whole developmental cycle in 3 commercial prawn nurseries, using a high-frequency sampling strategy and bacterial 16S rRNA amplicon sequencing. The bacterial α-diversity showed a U-shaped pattern across the developmental cycle. The bacterial community’s similarity followed a time-decay pattern, with community turnover rate of 0.011. Bacteroidetes, Actinobacteria, Alphaproteobacteria, and Gammaproteobacteria were the dominant phyla, and their relative abundance varied dramatically with prawn larval development. For example, the relative abundance of actinobacterial Microbacteriaceae and Cryomorphaceae (Bacteroidetes) significantly increased with prawn larval development (P<0.05), while that of two members of phyla Bacteroidetes, Flavobacteriaceae and Crocinitomicaceae decreased. pH is the most important environmental driver for the variations of bacterial diversity and composition. By using random forest analysis, we identified 12 biomarker taxa associated with prawn larval development. Specifically, Burkholderiaceae and Cyclobacteriaceae as the indicative taxa were detected in early (1—2d) and median stage (8—10d), respectively. While Saprospiraceae and Mycobacteriaceae accumulated in mid-late stages (16—21d). Bacterial co-occurrence patterns (mostly positive correlations) weakened and negative interactions accumulated with larval development. These findings reveal notable succession patterns and community assembly dynamics of bacterioplankton across whole prawn larval development, and will provide novel insights into microbiome management practices and prevent disease in prawn nursery.