摘要
沿海电厂产生的温排水已造成了较严重的环境问题,如生物病害和赤潮暴发频率增加。现有研究多关注温排水增温对浮游动、植物多样性的影响,而缺乏在物质能量循环过程起核心纽带作用的微生物对增温的响应和反馈。考虑到生态系统对增温的反馈取决于浮游植物的初级生产力和微生物异养呼吸之间的平衡,利用Illumina测序技术结合水体理化性质研究了象山港电厂温排水增温梯度下浮游细菌的空间分布特征。温排水预期的海水增温显著地增加了水体中硝氮(P=0.041,单因素方差分析)、化学需氧量(P<0.001)、油污(P=0.004)和余氯(P=0.003)的浓度;但降低了溶解氧(P=0.034)和叶绿素a(P=0.045)的含量。此外,相似性分析发现温排水增温显著地(r=0.338;P=0.042)改变了浮游细菌群落结构,空间分布遵循空间距离-群落相似性衰减(r=-0.582;P=0.026)模型,周转速率为0.0013。细菌多样性主要受水体溶解氧、化学需要量和叶绿素a的影响,分别控制了34.6%、20.1%和10.0%的多样性变异。冗余分析(RDA)群落变异主要受环境因子(包括温度、油污、溶解氧和叶绿素a)的影响,一共解释了55.6%的群落变异;增温仅解释了4.8%的群落变异。因此,浮游细菌群落结构主要受环境因子的影响,这种各因子对群落变异相对贡献比例的特征与增温主要通过改变水质和浮游植物特征,以间接作用影响细菌群落组成的观念一致。此外,细菌多样性和群落组成受不同环境因子的驱动。相比而言,空间距离只控制了较小比例的群落变异(7.1%)。此外,筛选到11个细菌科,这些科的相对丰度与增温幅度显著相关,变化特征与各科已知的生态功能相吻合,如海洋螺菌科(Oceanospirillaceae)中有些菌株能够降解石油污染物,其相对丰度在高油污浓度站点增加(油污浓度与增温幅度正相关,r=0.558;P=0.030);嗜温的弧菌科相对丰度与增温幅度正相关。综上,研究结果初步明确了浮游细菌群落对电厂温排水增温的响应特征,并筛选到敏感的细菌科来指示和预测增温对生态功能的潜在影响。
The thermal discharge of coastal power plants has resulted in serious environmental problems, such as the increasing frequency of disease in marine biota and red tides at a global scale. For this reason, previous studies have largely focused on the effects of thermal discharge on the diversity of zooplankton and phytoplankton species, whereas the study of the response and feedback of ecologically important planktonic microorganisms to thermal discharge is lacking. The ecosystem feedback response to elevated seawater temperature is dependent on the balance between primary production and heterotopic bacterial respiration. Therefore, we integrated Illumina sequencing technique and geochemical variables of seawater to investigate the spatial pattern of bacterioplankton communities, and identify the key factors shaping the pattern along a thermal gradient caused by the discharge from a power plant at Xiangshan Bay, Ningbo. Elevated temperature was significantly related to increased nitrate concentration (NO-3, P= 0.041, one-way analysis of variance), chemical oxygen demand (COD, P 〈 0.001), oil (P= 0.004), and residual chlorine (CI-, P 〈 0.003), whereas the levels of dissolved oxygen (DO, P=0.03g) and chlorophyll a (Chl a, P= 0.045) significantly decreased along the temperature gradient. In addition, an analysis of similarity (ANOSIM) revealed that thermal discharge significantly ( r = 0.338, P = 0.042) altered the structure of bacterioplankton communities, whereas the spatial distribution of the bacterioplankton communities followed a distance-similarity decay relationship in that the similarity between the bacterioplankton communities linearly decreased ( r = -0.582, P = 0.026) with increasing geographic distances, with a tumover rate of 0.0013. Multivariate regression tree showed that bacterial diversity was primarily affected by the levels of DO, COD, and seawater temperature, which respectively constrained 34,6%, 20.1%, and 10.0% of variation in bacterial diversity. A redundancy analysis (RDA) revealed that the environmental variables (including seawater temperature, oil, DO, and Chl a) explained 55.6% of the variation in the bacterioplankton communities. Thus, it appeared that the diversity and structure of bacterial communities were shaped by different factors. Notably, the direct effect of temperature only explained 4.8% of the variation. This is consistent with the premise that temperature increases have a moderate direct impact on bacterial community structure; however, water temperature indirectly affects water properties and causes a shift in the phytoplankton communities. By contrast, a smaller proportion of the community variation (7.1% ) was constrained by geographic distance. In particular, we screened 11 bacterial families, whose relative abundances were significantly associated with the discharge-induced temperature gradient. For a given bacterial family, the pattern of enrichment or decline was consistent with its known function. For example, bacterial species affiliated with Oceanospirillaceae have the ability to degrade and utilize petroleum hydrocarbons, whose relative abundance increased at higher oil content sites ( seawater oil contents linearly increased along the temperature gradient, r= 0.555; P = 0.050) ; whereas the relative abundance of the thermophilic Vibrionaceae species was positively associated with seawater temperature. Collectively, these results provide essential information on how the bacterioplankton community responds to thermal discharge, and identified sensitive bacterial families, which could be used to evaluate and predict the effects of thermal discharge on ecosystem function.
出处
《生态学报》
CAS
CSCD
北大核心
2016年第20期6574-6582,共9页
Acta Ecologica Sinica
基金
浙江省自然科学基金项目(LY15D060002)
宁波市自然科学基金项目(2015A610246)
浙江省重中之重学科开放基金项目(XKZSC1421)
关键词
温排水
浮游细菌群落结构
空间分布
指示细菌科
thermal discharge
bacterioplankton community structure
spatial distribution
bacterial bio-indicator family