Table_3_Differences in environmental microbial community responses under rice-crab co-culture and crab monoculture models under cyanobacterial bloom.DOCX

Cyanobacterial blooms (CBs) present significant challenges to Chinese mitten crab (CMC) culture, posing hazards to the aquatic microbial ecology. However, the current focus on the microbial ecological changes within the CMC culture system under the influence of CBs is somewhat insufficient. There’s an urgent need to analyze the microbial ecosystem of the CMC culture system under CBs. This study employed 16S rRNA gene amplicon sequencing to investigate the dynamics of the environmental microbial community in both the rice-crab co-culture (RC) and crab monoculture (CM) models. The results revealed that cyanobacteria reached high levels in the CM water in July, while they began to increase in the RC water in August. Notably, OTU147 (uncultured bacterium g_Planktothrix NIVA-CYA 15), identified as the dominant taxon associated with CBs, showed a significant linear relationship with TP, NO2−-N, and the N:P ratio. TP, TN, NO2−-N, and CODMn had a more pronounced impact on the structure of bacterial communities and cyanobacterial taxa in the water. The bacterial community structure involved in carbon metabolism displayed temporal succession in the water. The co-occurrence network of the bacterial community primarily consisted of Chloroflexi, Proteobacteria, and Firnicutes in the sediment, and Actinobacteria, Proteobacteria, Chloroflexi, and Bacteroidota in the water. In contrast, the co-occurrence network included different peripheral species in the sediment and water. Keystone species were predominantly represented by OTU22 (uncultured actinobacterium g_ hgcI clade) and OTU12 (uncultured Opitutae bacterium g_ norank) in the RC water, and by OTU25 (uncultured bacterium g_ Limnohabitans) in the CM water. TP, TN, NO2−-N, and CODMn were identified as the primary environmental factors influencing these keystone taxa within the culture water. In conclusion, this study on the microbial ecology of the CMC culture system under the influence of CBs provides valuable insights that can be instrumental in subsequent management efforts.

蓝藻水华（Cyanobacterial blooms, CBs）对中华绒螯蟹（Chinese mitten crab, CMC）养殖造成了显著挑战，同时对水生微生物生态系统构成威胁。然而，当前针对蓝藻水华影响下中华绒螯蟹养殖系统内微生物生态变化的研究仍存在不足，亟需剖析蓝藻水华胁迫下中华绒螯蟹养殖系统的微生物生态系统。本研究采用16S rRNA基因扩增子测序技术，探究了水稻-蟹综合种养（rice-crab co-culture, RC）与中华绒螯蟹单养（crab monoculture, CM）两种模式下养殖水体环境微生物群落的动态变化。结果显示，7月时单养模式水体中的蓝藻密度达到较高水平，而综合种养模式水体中的蓝藻则于8月才开始增殖。值得注意的是，操作分类单元(Operational Taxonomic Unit, OTU)147（未培养的Planktothrix属细菌NIVA-CYA 15）作为与蓝藻水华相关的优势类群，与总磷（TP）、亚硝酸盐氮（NO2−-N）及氮磷比（N:P）呈现显著线性相关关系。总磷、总氮（TN）、亚硝酸盐氮及高锰酸盐指数（CODMn）对水体中细菌群落结构与蓝藻类群的影响更为显著。参与碳代谢过程的细菌群落结构在水体中呈现出时间演替特征。细菌群落的共现网络在沉积物中主要以绿弯菌门（Chloroflexi）、变形菌门（Proteobacteria）以及厚壁菌门（Firmicutes）为主，而水体中的共现网络则以放线菌门（Actinobacteria）、变形菌门、绿弯菌门以及拟杆菌门（Bacteroidota）为主。与之相对，沉积物与水体中共现网络的外围类群存在差异。综合种养模式水体中的关键类群主要为OTU22（未培养的hgcI clade放线菌）与OTU12（未培养的Opitutae纲norank属细菌），单养模式水体中的关键类群则为OTU25（未培养的Limnohabitans属细菌）。总磷、总氮、亚硝酸盐氮及高锰酸盐指数被确定为影响养殖水体中上述关键类群的主要环境因子。综上，本研究针对蓝藻水华胁迫下中华绒螯蟹养殖系统的微生物生态学分析，可为后续养殖管理工作提供重要的理论参考与科学依据。