人类活动强度对锦江浮游细菌群落结构的影响

Effects of anthropogenic intensity on bacterioplankton community structure in Jinjiang River

为分析人类活动强度对锦江浮游细菌群落结构的影响机制,本研究于2021年1月(枯水期)和7月(丰水期)在锦江21个采样点采集表层水样,基于高通量测序技术研究浮游细菌群落特征,运用网络分析等方法阐明浮游细菌群落的交互作用,并探讨人类活动强度对其结构及构建过程的影响.结果表明:(1)枯/丰水期第一优势浮游细菌门均为变形菌门(Proteobacteria,53.08%/37.84%),其次是放线菌门(Actinobacteriota,30.89%/32.05%)和拟杆菌门(Bacteroidota,9.41%/13.94%);(2)与枯水期相比,丰水期浮游细菌群落的距离衰减效应更强,且其群落结构的季节变化大于人类活动强度影响下的空间变化,平均最近邻体指数(ENN_MN)和农田是影响河流细菌群落的最主要因子,而该群落构建过程主要由不同水化学指标驱动;(3)Proteobacteria和Patescibacteria是浮游细菌群落交互作用的关键物种,低干扰强度下浮游细菌群落交互网络的稳定性优于其他干扰强度,林地和温度(T)分别是影响枯/丰水期网络稳定性的主要环境因子.(4)人类活动强度变化可通过调节确定性和随机性过程平衡来影响浮游细菌群落构建,随着强度增加,确定性过程对浮游细菌群落构建的相对重要性不断增强,且人类活动强度每增加10%,将使浮游细菌群落交互网络的稳定性在枯/丰水期分别减少约6.38%和6.06%.以上结果为研究人类活动影响下河流生态系统监测和保护提供了理论基础.

To examine the mechanism underlying the effects of anthropogenic intensity on bacterioplankton communities,surfacewater samples were collected in 21 sampling sites in the Jinjiang River in January(dry season)and July(wet season),2021,and high-throughput sequencing technology was used to determine the characteristics of the bacterioplankton communities. Statistical methods including Network analysis were used to explore the assembly processes and co-occurrence relationships in the bacterioplankton communities under different human activity intensity. Results showed that:(1) the dominant phylum was Proteobacteria(53.08%/37.84%),followed by Actinobacteriota(30.89%/32.05%)and Bacteroidota(9.41%/13.94%)in both the dry and wet season.(2) Bacterioplankton communities had a stronger distance-decay relationship during the wet season compared to the dry season,and the variations of the community compositions between the seasons were greater than the spatial variation influenced by human activity intensity. Mean euclidean nearest neighbor index and farmland were the main factors that influenced the bacterioplankton community composition. The assembly processe of bacterioplankton was mainly driven by hydrochemical indicators.(3) Proteobacteria and Patescibacteria were the keystone species involved in the bacterioplankton interaction under different human activity intensity and the stability of bacterioplankton community interactions under low-anthropogenic intensity was higher than that under other anthropogenic intensities.(4) Human activity intensity influenced bacterioplankton community assembly via a regulation of the deterministic-stochastic balance,and the relative importance of deterministic processes to the construction of bacterioplankton communities increased with increasing human activity intensity. A 10% increase in human activity intensity would reduce the stability of the bacterioplankton community interaction network by approximately 6.38% and 6.06% during the dry/abundant water period,respectively.The above results can provide a theoretical basis for the study on environmental monitoring and classified management of aquatic ecosystems in rivers under the influence of human activity.