作为“地球第三极”, 青藏高原的平均海拔超过4,000 m, 拥有独特的高原高寒气候: 高寒、缺氧、日照时间长、辐射强、降水少(陈海生等, 2022; 杨清等, 2022)。位于青藏高原南部的雅鲁藏布江是青藏高原最主要的高寒水系, 该流域海拔高、地表物理性质复杂, 栖居于此的生物在全球气候变化中具有自身特殊的演化规律(Jiang et al, 2013; 李正飞等, 2022), 且有着明显的地理区系特点(李正飞等, 2022)。目前, 有关雅鲁藏布江浮游植物的研究主要集中在群落结构(马宝珊等, 2015)和基于完整性指数进行水质评价(李晓东等, 2023)等方面, 但针对浮游植物群落构建的研究仍然匮乏。本研究以雅鲁藏布江中上游自然水域为主体, 基于生态位理论(确定性过程)和中性理论(随机性过程), 通过时间和空间两个维度分析了浮游植物群落的物种组成、分布格局和构建模式, 并对浮游植物群落与环境因子进行相关性分析, 以揭示该流域浮游植物群落构建机制以及驱动浮游植物群落构建过程的影响因子, 以期为后续雅鲁藏布江浮游植物研究及青藏高原水环境保护提供数据支撑和参考。
1 材料与方法
1.1 研究区域
雅鲁藏布江是中国最长的高原河流, 发源于西藏西南部的杰马央宗冰川, 源头海拔5,590 m。雅鲁藏布江上游为高原, 宽山谷地貌, 海拔约4,500- 4,800 m; 中游河段为宽谷和窄谷相间的高山河谷地貌, 海拔约3,500-4,400 m, 地形地貌多样且复杂, 流域内水文状况和低海拔地区的河流存在很大区别(李海东等, 2013; 马宝珊等, 2015; Li et al, 2021), 如水源补给和降水状况等。雅鲁藏布江的水源补给以大气降水为主, 同时包括冰川融雪和地下水补给, 不同河段的补给来源所占比例有所差别(王欣等, 2016)。雅鲁藏布江中上游年降水量150-300 mm左右, 且集中在7-8月, 干湿季分明, 干季几乎无降水, 降水由东向西逐渐减少(刘善思, 2022; 刘心庭等, 2023)。
图1
图1
雅鲁藏布江中上游样点分布示意图。N1-N32为样点名称。YJA、YJB、YJC指3个海拔梯度, 其海拔分别为3,497-3,945 m、4,008-4,508 m和4,546-4,846 m。
Fig. 1
Distribution of sample sites in the middle and upper reaches of the Yarlung Zangbo River. The sample names are called N1-N32. YJA, YJB, YJC are three altitude gradients with 3,497-3,945 m, 4,008-4,508 m and 4,546-4,846 m, respectively.
1.2 样品采集
本次研究的采样时间为2019年8月(夏季)、11月(秋季)和2020年5月(春季)。根据《淡水浮游生物研究方法》(章宗涉和黄祥飞, 1991)中规定的方法进行浮游植物的采集和鉴定。定性样品用25# (孔径64 μm)浮游生物网在水下0-0.5 m处作“∞”型过滤, 在现场用4%甲醛固定保存后在室内利用LEICA DM500研究型光学显微镜鉴定物种。定量样品在0-0.5 m深度处采集1 L混合水样, 随后立即用鲁哥氏试剂固定, 样品带回实验室沉淀48 h后浓缩至50 mL, 移取0.1 mL浓缩匀液至0.1 mL计数框, 在10 × 40倍显微镜下全片计数, 每个样品计数2-3次(平行3次, 差异不超过15%)。浮游植物的鉴定参考迟若文(1990)、中国科学院青藏高原综合科学考察队(1992)、朱蕙忠和陈嘉佑(2000)以及胡鸿钧和魏印心(2016)。
1.3 水体理化因子的测定
现场使用HI98195高精度便携式多参数综合水质测试仪(HANNA, 意大利)测定水体酸碱度(pH)、总溶解固体(TDS)、盐度(Salt)及水温(WT), 使用HI98193微电脑溶解氧测定仪(HANNA, 意大利)测定溶解氧(DO); 使用HI98703微电脑多量程浊度测定仪(HANNA, 意大利)测定浊度(TUR); 利用FP-111直读式流速仪测定水流速度(V), 上述指标均分别进行3个平行检测。利用全球定位系统(Explorist500, 美国麦哲伦公司)记录样点经度、纬度和海拔(ALT)高度。
1.4 数据处理与分析
利用ArcGIS 10.8绘制采样地点图。利用Excel 2016软件计算浮游藻类丰度, 采用主坐标分析(principal coordinate analysis, PCoA)与相似性分析(analysis of similarities, ANOSIM)识别浮游植物群落时空分布的差异性。在计算浮游植物的群落距离(Bray-Curtis)前, 先对数据进行Hellinger转化, 该分析通过R 4.2.1的vegan包实现; 利用R 4.2.1中的vegan包计算不同时空浮游植物群落的α多样性(Simpson多样性指数、Pielou均匀度指数、物种丰富度指数), 并采用单因素方差分析(ANOVA)比较不同时空浮游植物α多样性的差异。通过中性模型(neutral community model, NCM) (Sloan et al, 2006)以及标准化随机率(normalized stochasticity ratio, NST) (Ning et al, 2019)评估确定性过程和随机性过程在浮游植物群落构建中的相对重要性。原则上标准化随机率数值范围在0-1之间, 但在实际应用过程中会出现 > 1的情况, 并采用校正随机率(modified stochsticity ratio, MST)的方法解决。MST值 < 0.5, 表明确定性过程占主导作用; MST值 > 0.5, 则表明随机性过程占主导作用(王吉毅等, 2022)。
通过浮游植物群落距离衰减模式(distance- decay patterns)对地理距离(基于Bray-Curtis距离)和环境距离(基于Euclidean距离)之间的关系进行讨论, 探究环境异质性(环境距离)和扩散限制(地理距离)对浮游植物群落构建过程的影响(Nekola & White, 1999; Hanson et al, 2012)。利用Mantel检验(Spearman相关系数)计算浮游植物各季节丰度和环境因子距离之间的相关性。Mantel检验使用软件R 4.2.1中的vegan包完成。在计算浮游植物的群落距离(Bray-Curtis)前, 先对数据进行Hellinger转化, 各环境因子(除pH以外)经过log(x + 1)转化; 共现网络构建利用R 4.2.1中的psyc包进行Spearman相关性分析, 选择具有相关性(|R| > 0.6, P < 0.05)的节点代入分析, 利用Gephi (V0.9.7)软件进行计算与可视化处理。本文除以上所述的绘图均在R 4.2.1和Origin 2021软件中完成。
2 结果
2.1 浮游植物群落结构与α多样性的时空动态变化
雅鲁藏布江中上游3个季节共鉴定出浮游植物452种, 隶属于8门11纲24目44科121属, 以硅藻门为主, 共有342种(79.66%); 其次为蓝藻门和绿藻门, 各50种(11.06%) (图2c)。从季节上看, 春季共鉴定浮游植物188种, 隶属4门6纲14目26科48属; 夏季共鉴定浮游植物181种, 隶属于4门6纲17目30科30属; 秋季共鉴定浮游植物204种, 隶属于8门10纲19目27科85属。物种数为秋季 > 春季 > 夏季; 物种丰度为夏季 > 春季 > 秋季(图2a)。从空间上看, YJA共鉴定浮游植物224种; YJB共鉴定浮游植物246种; YJC共鉴定浮游植物246种。物种数排序为YJC = YJB > YJA; 物种丰度排序为YJB > YJC > YJA (图2b)。
图2
图2
雅鲁藏布江中上游浮游植物群落结构特征。(a)各季节浮游植物群落丰度变化; (b)各海拔浮游植物群落丰度变化; (c) 3个季节不同浮游植物类群的相对丰度和物种数的空间分布。YJA、YJB、YJC见
Fig. 2
Phytoplankton community structure in the upper and middle reaches of the Yarlung Zangbo River. (a) Variation of phytoplankton abundance in different seasons; (b) Variation of phytoplankton abundance at different elevations; (c) Spatial distribution of the relative proportion of abundance and species number of different groups of phytoplankton communities in three seasons. YJA, YJB, YJC see
利用Simpson多样性指数、Pielou均匀度指数和物种丰富度指数3个参数来衡量雅鲁藏布江不同时空下浮游植物群落的α多样性(图3)。通过方差分析检验发现, 这3个参数在时空变化上存在显著差异(P < 0.05)。Simpson指数在季节上表现为春季(0.89) > 秋季(0.77) > 夏季(0.56); 海拔上表现为YJA (0.91) > YJB (0.89) > YJC (0.87)。Pielou指数在季节上表现为春季(0.83) > 秋季(0.76) > 夏季(0.69); 海拔上表现为YJA (0.76) > YJB (0.73) > YJC (0.69)。物种丰富度指数在季节上表现为春季(21.41) > 夏季(20.66) > 秋季(15.88); 海拔上表现为YJA (53.67) > YJC (50.00) > YJB (49.38)。
图3
图3
雅鲁藏布江中上游浮游植物群落的α多样性。S: 春季; SU: 夏季; A: 秋季; TOTAL: 总流域。YJA、YJB、YJC见
Fig. 3
Phytoplankton community α-diversity in the upper and middle reaches of the Yarlung Zangbo River. S, Spring; SU, Summer; A, Autumn; TOTAL, The total watershed. YJA, YJB, YJC see
2.2 浮游植物群落β多样性及距离衰减
基于Bray-Curtis距离的主坐标分析结果表明, 雅鲁藏布江中上游浮游植物群落在时空分布上存在差异性。时间上, 主坐标的第一轴能解释雅鲁藏布江中上游浮游植物群落5.49%的变化, 第二轴能解释7.56%的变化; 空间上主坐标的第一轴能解释雅鲁藏布江中上游浮游植物群落21.53%的变化, 第二轴能解释27.89%的变化。相似性分析结果表明, 雅鲁藏布江中上游浮游植物群落在不同季节(R =0.546, P < 0.01)和海拔(R = 0.343, P < 0.01)间存在时空分布差异性(图4)。
图4
图4
基于雅鲁藏布江中上游浮游植物群落Bray-Curtis相似性的主坐标分析(PCoA)。(a)不同季节浮游植物群落的主坐标分析(PCoA); (b)不同海拔浮游植物群落主坐标分析(PCoA)。YJA、YJB、YJC见
Fig. 4
Principal coordinate analysis (PCoA) of phytoplankton community based on Bray-Curtis similarity in the upper and middle reaches of the Yarlung Zangbo River. (a) PCoA of the phytoplankton community in different seasons; (b) PCoA of the phytoplankton community at different altitudes. YJA, YJB, YJC see
基于Bray-Curtis距离的回归分析结果表明, 除春季以外, 不同时空的浮游植物群落均存在地理衰减, 但仅夏季(Adjusted R2 = 0.027, P < 0.001)与YJB (Adjusted R2 = 0.068, P < 0.05)的浮游植物群落有显著性(图5)。基于Euclidean距离的线性分析结果表明, 不同时空浮游植物群落相似性均随环境距离的增加而呈现显著衰减效应(P < 0.001) (图5)。不同季节衰减趋势为春季(Adjusted R2 = 0.287) > 夏季(Adjusted R2 = 0.044) > 秋季(Adjusted R2 = 0.042); 不同海拔衰减趋势为YJC (Adjusted R2 = 0.352) > YJA (Adjusted R2 = 0.305) > YJB (Adjusted R2 = 0.146)。总体上, 环境距离衰减趋势大于地理距离衰减趋势。
图5
图5
雅鲁藏布江中上游浮游植物群落距离衰减分析。a-c、g-i分别为春季、夏季、秋季、YJA、YJB和YJC浮游植物群落地理距离衰减; d-f、j-l分别为春季、夏季、秋季、YJA、YJB和YJC浮游植物群落环境距离衰减。YJA、YJB、YJC见
Fig. 5
Distance decay analysis of phytoplankton community in the upper and middle reaches of the Yarlung Zangbo River. a-c, g-i, The geographic distance attenuation of phytoplankton in spring, summer, autumn, YJA, YJB, and YJC, respectively; d-f, j-l, The environmental distance decay change of phytoplankton community in spring, summer, autumn, YJA, YJB, and YJC, respectively. YJA, YJB, YJC see
2.3 浮游植物群落共现网络分析
共现网络分析结果显示, 夏季与秋季浮游植物群落网络中边的数量高于春季; YJC与YJB浮游植物群落网络中边的数量高于YJA。不同季节与海拔梯度间浮游植物种间连接以正相关边为主, 表明浮游植物群落间协同作用强于竞争作用。此外, 6个网络的模块化系数为0.765-0.853, 表明共现网络具有模块化结构; 其平均路径长度为3.302-6.981。季节上, 图密度为夏季(0.042) > 春季(0.037) > 秋季(0.033), 表明浮游植物群落间互作关系在夏季较为复杂、秋季较为简单; 海拔上, 图密度为YJC (0.085) > YJA (0.082) > YJB (0.078), 说明浮游植物群落间互作关系在YJC较为复杂、YJB较为简单(图6, 表1)。
图6
图6
雅鲁藏布江中上游浮游植物群落共现网络。a-c分别为春季、夏季、秋季浮游植物群落; d-f分别为YJA、YJB、YJC浮游植物群落。YJA、YJB、YJC见
Fig. 6
Phytoplankton community co-occurrence network in the upper and middle reaches of the Yarlung Zangbo River. a-c, Spring, summer, and autumn phytoplankton communities, respectively; d-f, YJA, YJB, YJC phytoplankton communities, respectively. YJA, YJB, YJC see
表1
浮游植物群落共现网络的拓扑结构特征。YJA、YJB、YJC见
Table 1
| 网络拓扑指标 Network topological indicators | 春季 Spring | 夏季 Summer | 秋季 Autumn | YJA | YJB | YJC |
|---|---|---|---|---|---|---|
| 节点数 Number of nodes | 188 | 181 | 204 | 224 | 246 | 246 |
| 边数 Edges | 642 | 686 | 687 | 2,050 | 2,365 | 2,558 |
| 连接部件 Connected component | 45 | 40 | 43 | 1 | 3 | 1 |
| 网络直径 Network diameter | 15 | 18 | 12 | 9 | 8 | 11 |
| 平均度 Average degree | 6.830 | 7.580 | 6.735 | 18.304 | 19.228 | 20.797 |
| 模块化系数 Modularity coefficient | 0.820 | 0.829 | 0.806 | 0.850 | 0.765 | 0.853 |
| 图密度 Density of figure | 0.037 | 0.042 | 0.033 | 0.082 | 0.078 | 0.085 |
| 平均聚类系数 Mean clustering coefficient | 0.854 | 0.847 | 0.792 | 0.841 | 0.750 | 0.841 |
| 平均路径长度 Mean path length | 6.147 | 6.981 | 5.332 | 3.953 | 3.302 | 3.851 |
| 正相关比例 Positive correlation (%) | 100 | 100 | 100 | 99.375 | 99.493 | 97.757 |
| 负相关比例 Negative correlation (%) | 0 | 0 | 0 | 0.625 | 0.507 | 2.243 |
2.4 浮游植物的群落构建机制
中性模型(NCM)和标准化随机率综合分析结果如图7(a-f)所示, 在时间上, 中性群落模型的整体拟合优度(R2)表现为春季(R2 = 0.835) > 夏季(R2 = 0.613) > 秋季(R2 = 0.264), 表明浮游植物群落的解释率随季节逐渐降低, 即随机性过程的重要性在群落中逐渐减少; 并且, 春季到秋季的浮游植物群落的迁移率Nm分别是3、2、1, 说明浮游植物群落的扩散程度随着季节变化逐渐下降。在空间上, YJB (R2 = 0.616)浮游植物群落的解释率最高, 其次是YJA (R2 = 0.539), YJC (R2 = 0.257)最低; 并且, YJA的迁移率(Nm = 10)高于YJB (Nm = 8)与YJC (Nm = 6), 说明浮游植物群落在YJA的物种扩散高于YJB与YJC。表明随机性过程在不同空间下都对浮游植物群落的形成起到一定作用。
图7
图7
雅鲁藏布江中上游浮游植物群落中性模型(a-f)和校正随机率(MST) (g-i)。频率高于模型预测值的物种显示为黄色; 频率较低的物种显示为红色; 预测范围内的物种显示为绿色; 蓝色虚线表示模型预测的95%置信区间。R2为中性群落模型的整体拟合优度, Nm是元群落规模(N)与迁移率(m)的乘积, 量化了对群落之间扩散的估计。a-c分别为春季、夏季、秋季浮游植物群落; d-f分别为YJA、YJB、YJC浮游植物群落; (g) 3个季节浮游植物群落MST; (h) 3个海拔梯度浮游植物群落MST; (i)校正随机率在不同季节和海拔梯度上的变化。S: 春季; SU: 夏季; A: 秋季。YJA、YJB、YJC见
Fig. 7
Neutral model of phytoplankton community (a-f) and modified stochasticity ratio (MST) (g-j). Species whose frequency is higher than predicted by the model are shown in yellow; Less frequent species are shown in red; Species within the predicted range are shown in green; The blue dashed line represents the 95% confidence interval for the model's prediction. R² is the overall goodness of fit of the neutral community model, and Nm is the product of meta-community size (N) and mobility (m), quantifying the estimate of diffusion between community assembly. a-c, Spring, summer, and autumn phytoplankton communities, respectively; d-f, YJA, YJB, YJC phytoplankton communities, respectively; (g) Three seasonal phytoplankton communities MST; (h) Three altitudinal gradient phytoplankton communities MST; (i) Modified stochasticity ratio in different seasons and altitude gradients. S, Spring; SU, Summer; A, Autumn. YJA, YJB, YJC see
使用校正随机率量化确定性过程和随机性过程在浮游植物群落构建中的相对重要性。如图7(g-i)所示, 校正随机率和中性群落模型结果相似。在时间上, 春季和夏季浮游植物群落的校正随机率数值分布均高于50%阈值线, 且春季大于夏季, 表明在春季、夏季的浮游植物群落中, 随机性过程占主导。秋季浮游植物群落的校正随机率数值分布低于50%阈值线, 这表示秋季浮游植物群落的确定性过程占主导。在空间上, YJB浮游植物群落的校正随机率数值分布高于50%阈值线, 而YJA与YJC的校正随机率数值分布低于50%阈值线, 这说明YJA与YJC浮游植物群落均受确定性选择影响更大, 且YJA受到的确定性影响更大。
2.5 浮游植物群落与环境因子的相关性
利用Mantel检验探究雅鲁藏布江中上游浮游植物群落与环境因子间的相关性结果如图8所示, 在时间上, 春季浮游植物群落与pH、总溶解性固体、盐度极显著相关(P < 0.01), 与海拔显著相关(P < 0.05); 夏季浮游植物群落与水流速度极显著相关(P < 0.01), 与pH、总溶解性固体、盐度、溶解氧显著相关(P < 0.05); 秋季浮游植物与pH、总溶解性固体、盐度极显著相关(P < 0.01), 与浊度显著相关(P < 0.05)。空间上, YJA浮游植物群落与总溶解性固体与盐度极显著性相关(P < 0.01), 与溶解氧、浊度与水流速度显著相关(P < 0.05); YJB浮游植物群落与水流速度极显著相关(P < 0.01); YJC浮游植物与pH极显著相关(P < 0.01), 与总溶解性固体、盐度与水流速度显著相关(P < 0.05)。在所测定的水环境因子中, 总溶解性固体、盐度和水流速度是影响浮游植物群落构建的主要因子, 对浮游植物的分布均具有限制作用。
图8
图8
雅鲁藏布江中上游浮游植物群落与环境因子相关性分析。TDS: 总溶解固体; WT: 水温; DO: 溶解氧; TUR: 浊度; V: 水流速度; ALT: 海拔; Salt: 盐度。YJA、YJB、YJC见
Fig. 8
Correlation analysis between phytoplankton communities and environmental factors. TDS, Total dissolved solid, WT, Water temperature; DO, Dissolved oxygen; TUR: Turbidity; WS, Waterflow speed; ALT, Altitude; Salt, Salinity. YJA, YJB, YJC see
3 讨论
3.1 浮游植物群落的时空分布格局及其多样性
浮游植物群落结构特征的变化与水环境、水文、水生物等因素密切相关。季节更替与海拔梯度变化往往伴随着流域内水文条件的改变, 浮游植物群落会通过调节生态适应性来维持其生态系统的动态平衡。本研究结果显示, 硅藻为雅鲁藏布江中上游的主要藻类, 其次是蓝藻和绿藻。这与雅鲁藏布江谢通门江段(马宝珊等, 2015)和支流尼洋河(裴国凤, 2012)的调查结果相似。不同时空的浮游植物群落丰度不同, 夏季浮游植物的丰度最高, 这可能与夏季水体有机物大量增加有关(杨清等, 2022)。在空间上, YJC和YJB的绿藻丰度比YJA大, 这可能与绿藻门是耐低温的嗜冷生物有关, 它们能够忍受长时间的不活跃状态, 并在有利的条件下恢复生长(Novakovskay et al, 2022)。
浮游植物群落的α多样性在不同时空下有显著差异(P < 0.05) (图3)。不同时空下, 浮游植物群落的Pielou均匀度指数均高于0.6, 说明雅鲁藏布江中上游浮游植物群落分布较均匀。春季和秋季浮游植物群落的Simpson指数和Pielou均匀度指数均大于夏季, 这与张春霞等(2022)在丹江口水库的研究结果不同。可能的原因是, 雅鲁藏布江夏季河流稳定性差, 给浮游植物提供的资源和空间相对较小, 种间和种内竞争加剧, 物种多样性随之受影响(李晓东等, 2023), Mantel分析也说明, 夏季的浮游植物群落与水流速度显著相关(图8b)。夏季与春季的物种丰富度指数高于秋季, 这可能与秋季的水流量小, 浮游植物生长、迁移等受到的环境干扰更大有关。不同海拔梯度上, YJA的Simpson指数、Pielou均匀度指数和物种丰富度指数均大于YJB和YJC。可能的原因是, 随着海拔的增加使得主要通过水流扩散的浮游植物的迁移受到阻碍, 均匀度下降。且极端的环境让大部分浮游植物难以生存和定居, 故而YJB和YJC的浮游植物物种多样性和丰富度也下降(李正飞等, 2022)。
本研究结果显示雅鲁藏布江中上游浮游植物的时间与空间分布表现出明显的区域性差异, 表明不同季节与海拔梯度的浮游植物群落结构具有显著差异(图4)。在地理距离中(图5), 除春季外, 不同时空的浮游植物群落存在地理衰减, 这与浙江省不同季节水域微生物群落相似性皆呈现显著地理衰减的研究结果不同(Wang et al, 2020), 春季浮游植物群落不存在地理衰减可能是由于春季的物种相似性高且物种迁移和扩散能力较强, 物种均匀度也更高, 这与中性模型的研究结果相同, 春季的迁移率较夏、秋大。在环境距离中(图5), 不同时空浮游植物群落的相似度皆呈现显著衰减趋势, 也说明了不同时空下环境异质性的增加。这与在长江中硅藻的研究结果相似(Wang et al, 2019), 即环境距离在限制浮游藻类的组成和分布方面都发挥了重要作用, 进而使得环境异质性可能是导致浮游藻类生态位分化的重要原因之一。此结果也说明雅鲁藏布江中上游浮游藻类的分布受扩散限制和环境选择共同影响。
3.2 浮游植物群落与环境因子的关系
根据Mantel分析的结果(图8), 季节上, 浮游植物群落皆与pH、总溶解性固体和盐度相关。碱性环境对浮游植物光合作用有利, 在碱性水体中浮游植物具有较高的初级生产力(陈康等, 2022)。雅鲁藏布江中上游流域pH平均值在8以上, 呈碱性, 有利于光合作用; 总溶解性固体对浮游植物群落影响显著, 这也许与雅鲁藏布江中上游的生态环境和人类活动有关, 如农业施肥、放牧活动和生活污水的大量排放等均会增加水体中溶解的无机物和有机物, 从而导致电导率以及河流中营养物质浓度增加, 对该流域生物群落(如鱼类、浮游植物、底栖动物等)的生长发育造成显著影响(Walker & Pan, 2006; He et al, 2015; 白海锋等, 2021; Han et al, 2021)。在大量研究中(Sun & Wang, 2017; 卜亚谦等, 2019; 侯朝伟等, 2020), 盐度是影响浮游生物空间分化的主要因素之一, 在一定程度上影响藻类细胞的渗透压、漂浮性、营养盐吸收、色素含量及光合放氧等, 过高或过低的盐度均会对藻细胞造成伤害, 使浮游藻类无法生存(高兵兵, 2012; 钟佳丽等, 2019); 溶解氧是水生生物生存的必要条件之一, 能够有效表征水体受到生物作用的影响程度, 溶解氧含量可通过浮游植物的光合作用释放氧气得到增加; 当溶解氧含量较低、水体氧气不足时, 浮游植物的生长会受到抑制(杨清等, 2022)。此外, 海拔、水流速度、浊度也是影响浮游植物群落的因素之一。水流速度是影响藻类生长的关键动力学因子, 水体扰动能够使得底泥悬浮, 促进营养盐的释放(李正飞等, 2022)。浊度与总溶解性固体相似, 浊度降低, 透明度上升, 促进浮游植物得到充足阳光生长繁殖。空间上, 溶解氧、总溶解性固体、盐度、浊度和水流速度是影响YJA浮游植物群落的主要环境因子; 水流速度是影响YJB浮游植物群落的主要因素; pH、总溶解性固体、盐度和水流速度是影响YJC浮游植物群落的主要环境因子。
3.3 浮游植物群落的构建过程
生态过程包括确定性过程和随机性过程, 可以同时影响微生物群落的构建, 确定性过程和随机性过程之间的平衡会影响群落中物种的聚集(Lei et al, 2021)。中性模型和标准化随机率广泛应用于生态过程的分析, 是一种量化确定性过程和随机性过程在群落构建中相对重要性的有效方法。
在季节上, 春季、夏季和秋季的模型整体拟合度(R2)与校正随机率值从春季到秋季逐渐减弱, 扩散略有减弱, 说明浮游植物群落的构建过程已从生态随机性逐渐转变为确定性。夏季和春季(MST值 > 50%)以随机性过程为主, 这可能与较大的降水量导致河流流量增加有关。降雨将微生物从周围环境系统(如土壤、沉积物和流域)冲刷到河流中, 使得浮游植物的物种扩散在夏季和春季高于秋季, 增加了夏季和春季的随机性过程, 这与锦江浮游细菌群落构建的结果相似(吴波波等, 2022)。在太湖流域浮游细菌群落构建中也显示(Zhang et al,2022), 扩散事件(随机性过程)在降水量大时更容易发生。秋季水量小, 河流连通性下降, 浮游植物的迁移率也小, 从而促进了生境异质性和群落异质性, 使得环境梯度导致的确定性过程对浮游植物群落产生了重要作用。从另一个角度来看, 春季的R2值和MST都大于夏季, 即春季的随机性过程(扩散过程)大于夏季, 这可能与春夏两季浮游植物群落的生态位宽度有关, 生态位宽度较宽的浮游植物群落受环境变化的影响较小。当它们通过水流波动被动扩散到新的栖息地时, 可能更容易定居, 通过均匀扩散使群落更加相似。
在空间上, 浮游植物群落的中性模型拟合度R2均达到0.2以上, 这说明中性过程在各海拔梯度的浮游植物群落的构建中均起到一定作用。随着海拔的增加, 物种扩散逐渐减弱, 这可能与随着海拔的升高水温等环境因子的变化限制了浮游植物群落的扩散有关。校正随机率的结果表明, 随机性在YJB (MST > 50%)浮游植物群落里占主导作用, 确定性在YJA和YJC (MST < 50%)浮游植物群落里占主导作用。这说明, 从YJA (3,497-3,945 m)、YJB (4,008-4,508 m)到YJC (4,546-4,846 m), 海拔不断升高, 浮游植物群落的确定性过程呈现增强、减小后增强的现象。这可能与不同海拔梯度流域的环境压力有关。确定性过程受环境压力的影响较大, 随着海拔梯度的变化, 浮游植物面临的环境压力也发生变化, 加上具体生境的影响, 导致确定性过程在群落构建中的占比发生变化; 当受到的环境压力较低时, 浮游植物群落可以自由繁殖生长, 从而导致群落构建中的随机性过程占主导地位(吴波波等, 2022)。YJB的环境距离衰减趋势较低也说明YJB的环境异质性较低, 这可能导致浮游植物群落的栖息地偏好降低, 从而随机性过程高于确定性过程。而YJA和YJC的环境异质性较大, 从而导致确定性过程主导了群落的构建。
但中性模型并没有100%地解释浮游植物群落的变化, 表明浮游植物群落的其他构建过程与机制同时存在, 导致了非随机分布的产生, 这些机制包括环境选择和物种间的相互作用等。因此, 利用共现网络分析作进一步补充。
3.4 浮游植物群落的共现网络分析
为了对浮游植物群落构建机制中环境因子和空间因子所无法解释的部分做补充, 利用共现网络分析了浮游植物群落物种间相互关系及其对塑造群落结构的重要意义。网络结构可以反映群落的复杂性和稳定性(郭馨等, 2022)。在复杂的生态环境中, 物种间的竞争关系随着环境的变化而波动, 导致不同时空浮游植物群落的变化。共现网络的节点、平均聚类系数、平均路径长度、平均度和模块等网络属性均表现出时空变化。这些网络属性可表示物种间复杂性、传递效率、能量和信息的效率以及对网络外部环境的敏感性(Hunt & Ward, 2015; Chen et al, 2021)。本研究发现, 在时空维度上, 模块化系数均大于0.4, 物种之间的互作关系均以协作关系为主。这说明, 群落间“小世界”或“小生境”现象明显(Deng et al, 2012)。且在极端生境中, 物种间的互作关系以协作为主(Deng et al, 2012)。浮游植物不同门之间有着密切的相关性, 生态位相近或重叠的种类同时出现于同一模块中, 不同模块的种类生态位差别较大, 几乎每个模块均由两种或两种以上的浮游植物门共同构成(郭馨等, 2022)。这说明不同门的浮游植物群落生态位有重叠, 有相异, 在同一环境中形成物种共存, 维持了群落结构的稳定性。在季节上, 春季和夏季的平均聚类系数、平均度、图密度和平均路径长度高于秋季, 说明春、夏两季的网络更为复杂和稳定, 连接更为紧密, 应对环境干扰的反应更为迅速。这可能是由于夏季、春季光照较强, 浮游植物大量繁殖, 优势门类的连通性更高, 使得春夏两季的网络更加复杂。在空间上, YJC的平均度、图密度、网络直径、平均聚类系数高于YJB和YJA, 说明YJC网络的连接度更为紧密, 稳定性更高, 抗干扰能力最强, 对环境变化敏感。其原因可能是YJC的环境更极端, 浮游藻类的联结更紧密, 使得YJC的网络更加复杂。
综上, 环境异质性、扩散限制和物种间相互作用共同影响了雅鲁藏布江中上游浮游植物群落的构建, 其中, 确定性过程(环境选择)主导了其构建过程。但是除了上述因素, 在浮游植物群落的构建上仍有许多无法解释的因素。一些可能的解释是, 其他重要的环境因子变量未包括在内, 如本研究没有考虑该区域营养效应、放牧等因素对浮游植物群落的影响。
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PMID:22580365
[本文引用: 1]
Recently, microbiologists have established the existence of biogeographic patterns among a wide range of microorganisms. The focus of the field is now shifting to identifying the mechanisms that shape these patterns. Here, we propose that four processes - selection, drift, dispersal and mutation - create and maintain microbial biogeographic patterns on inseparable ecological and evolutionary scales. We consider how the interplay of these processes affects one biogeographic pattern, the distance-decay relationship, and review evidence from the published literature for the processes driving this pattern in microorganisms. Given the limitations of inferring processes from biogeographic patterns, we suggest that studies should focus on directly testing the underlying processes.
Altitudinal pattern of stream periphyton biomass in tributaries of the Lancang-Mekong River: An indicator of anthropogenic impact?
Mechanisms of community organization and spatiotemporal patterns of soil microbial communities
土壤微生物群落构建理论与时空演变特征
Spatial niche of dominant zooplankton species in Yantai offshore waters
烟台近海浮游动物优势种空间生态位研究
A network-based approach to disturbance transmission through microbial interactions
DOI:10.3389/fmicb.2015.01182
PMID:26579091
[本文引用: 1]
Microbes numerically dominate aquatic ecosystems and play key roles in the biogeochemistry and the health of these environments. Due to their short generations times and high diversity, microbial communities are among the first responders to environmental changes, including natural and anthropogenic disturbances such as storms, pollutant releases, and upwelling. These disturbances affect members of the microbial communities both directly and indirectly through interactions with impacted community members. Thus, interactions can influence disturbance propagation through the microbial community by either expanding the range of organisms affected or buffering the influence of disturbance. For example, interactions may expand the number of disturbance-affected taxa by favoring a competitor or buffer the impacts of disturbance when a potentially disturbance-responsive clade's growth is limited by an essential microbial partner. Here, we discuss the potential to use inferred ecological association networks to examine how disturbances propagate through microbial communities focusing on a case study of a coastal community's response to a storm. This approach will offer greater insight into how disturbances can produce community-wide impacts on aquatic environments following transient changes in environmental parameters.
Longitudinal patterns of macroinvertebrate communities in relation to environmental factors in a Tibetan-Plateau River system
DOI:10.1016/j.quaint.2013.02.034 URL [本文引用: 1]
The daily effect is more important than the diurnal effect when shaping photosynthetic picoeukaryotes (PPEs) communities in Lake Taihu at a small temporal scale
Community structure and diversity distribution pattern of sandy plants in the middle and upper reaches of the Yarlung Zangbo River
DOI:10.5814/j.issn.1674-764x.2021.01.002
[本文引用: 1]
The Yarlung Zangbo River Basin is an important populated area in Tibet, and its plant community structure and diversity pattern have attracted the attention of many scholars. In this paper, the distribution pattern of plant diversity and the environmental factors impacting it in the middle and upper reaches of the Yarlung Zangbo River are revealed and discussed through sample surveys and climate and habitat data. The results show that the plant communities in the study area can be divided into seven types according to the dominant species: Artemisia minor + Stipa purpurea, Artemisia wellbyi + Festuca ovina, Potentilla fruticosa + Orinus thoroldii, Trikeraia hookeri + Artemisia frigida, Kobresia pygmaea, Sophora moorcroftiana + Artemisia hedinii, and Sophora moorcroftiana + Pennisetum centrasiaticum. Plant diversity decreases with decreasing longitude, increasing latitude, and increasing altitude; and the diversity distribution pattern in the study area has distinct zonal characteristics. Water and heat are the main factors which affect the distribution of vegetation types. The explanation rates of water and heat for the plant diversity distribution pattern were 19.3% and 5.7%, respectively, while the spatial variation explained by these two factors together was 60.8%. Therefore, the coupling effect is obvious.
The coupling relationship between variations of NDVI and change of aeolian sandy land in the Yarlung Zangbo River basin of Tibet, China
雅鲁藏布江流域NDVI变化与风沙化土地演变的耦合关系
Response of river ecosystem health status to water environmental factors in the middle reaches of Yarlung Zangbo River
DOI:10.13227/j.hjkx.202211063 [本文引用: 2]
雅鲁藏布江中游河流生态系统健康状态对水环境因子的响应
DOI:10.13227/j.hjkx.202211063 [本文引用: 2]
Species diversity and driving factors of benthic macroinvertebrate assemblages in the middle and lower reaches of the Yarlung Zangbo River
DOI:10.17520/biods.2021431
[本文引用: 4]
<p id="p00005"><strong>Aims:</strong> The Yarlung Zangbo River basin supports rich and unique biological resources, which makes it a global biodiversity hotspot. However, surveys on benthic macroinvertebrates in this river basin are far from sufficient. To fill this gap, this study focused on the middle and lower reaches of the Yarlung Zangbo River, where macroinvertebrates were sampled from the main stream and tributaries in autumn (October 2015) and spring (March 2016). <br><strong>Methods:</strong> One-way ANOVA was used to examine the differences of abundance, biomass and ecological indices between the main stream and tributaries. Canonical analysis of principal coordinates (CAP) was adopted to test if community structures varied among different site groups. Canonical correspondence analysis (CCA) was Applied to identify the key environmental factors that significantly influence the community structure of macroinvertebrates during each season. <br><strong>Results:</strong> A total of 270 species were identified, belonging to 5 phyla 8 classes 20 orders and 92 families. The community included 246 aquatic insects, 14 oligochaetes, 4 mollusks and 6 others. The average density was 939.1 ind./m<sup>2</sup>, and the average biomass was 5.44 g/m<sup>2</sup>. 184 and 214 macroinvertebrate species were collected in spring and autumn, respectively. The dominant species were aquatic insects that preferred clean and cold water, including <i>Baetis </i>sp., <i>Baetiella </i>sp., <i>Simulium </i>sp., <i>Micropsetra</i> sp. and <i>Brachycentrus </i>sp. The community structure, density and diversity indices exhibited significant temporal and spatial variation, and the diversity in tributaries was significantly higher than that of the main stream. CCA analysis indicated that environmental factors including altitude, velocity, river width and substrate types were key factors structuring the benthic community in the Yarlung Zangbo River. <br><strong>Conclusion:</strong> The variation in community structure and diversity pattern were mainly derived from the variable climate types and geological barriers in the Grand Canyon area. This study can provide important basis and reference for macroinvertebrate diversity assessments and environmental monitoring in the Yarlung Zangbo River basin.</p>
雅鲁藏布江中下游底栖动物物种多样性及其影响因素
DOI:10.17520/biods.2021431
[本文引用: 4]
雅鲁藏布江流域维系着丰富而独特的生物资源, 是全球生物多样性研究的热点区域。然而, 该流域底栖动物多样性的调查却极不充分。本文于2015年10月和2016年3月对雅鲁藏布江干流(朗县至墨脱段)和主要支流的底栖动物进行了调查, 并采用单因素方差分析(one-way ANOVA)和典范对应分析(canonical correspondence analysis)等对群落多样性格局进行解析。共采集到底栖动物270种, 隶属于5门8纲20目92科, 包括昆虫纲246种, 寡毛纲14种, 腹足纲4种, 其他动物6种。春季和秋季分别采集到底栖动物184种和214种, 优势种均以喜清洁和冷水的水生昆虫为主, 包括四节蜉属一种(Baetis sp.)、花翅蜉属一种(Baetiella sp.)、蚋属一种(Simulium sp.)、小突摇蚊属一种(Micropsetra sp.)和短石蛾属一种(Brachycentrus sp.)等。全流域平均密度为939.1 ind./m<sup>2</sup>,sp.)等。平均生物量为5.44 g/m<sup>2</sup>。底栖动物的物种组成、密度和多样性在季节和区域之间存在一定差异, 支流的多样性显著高于干流。典范对应分析显示, 海拔、流速、河宽和底质类型等环境因子是影响雅鲁藏布江流域底栖动物群落结构的关键环境因素, 而大峡谷地区多变的气候类型和地理阻隔是造成群落变化的根本原因。本研究可为雅鲁藏布江流域底栖动物多样性评估和环境监测提供重要的基础和参考。
The diversity of autumn birds in the upper and middle reaches of the Yarlung Zangbo River
雅鲁藏布江中上游流域秋季鸟类多样性
Rare earth elements in the upper reaches of Yarlung Zangbo River
雅鲁藏布江上游干支流河水稀土元素地球化学特征研究
Biogeographic patterns and assembly mechanisms of bacterial communities differ between habitat generalists and specialists across elevational gradients
DOI:10.3389/fmicb.2019.00169
PMID:30804920
[本文引用: 1]
A core issue in microbial ecology is the need to elucidate the ecological processes and underlying mechanisms involved in microbial community assembly. However, the extent to which these mechanisms differ in importance based on traits of taxa with different niche breadth is poorly understood. Here, we used high-throughput sequencing to examine the relative importance of environmental selection and stochastic processes in shaping soil bacterial sub-communities with different niche breadth (including habitat generalists, specialists and other taxa) across elevational gradients on the subalpine slope of Mount Wutai, Northern China. Our findings suggested that the composition of soil bacterial communities differed significantly different among elevational gradients. According to the niche breadth index, 10.9% of OTUs were defined as habitat generalists (B-value >8.7) and 10.0% of OTUs were defined as habitat specialists (B-value <1.5). Generalists and specialists differed distinctly in diversity and biogeographic patterns across elevational gradients. Environmental selection (deterministic processes) and spatial factors (stochastic processes) seemed to determine the assembly and biogeography of habitat generalists. However, for specialists, deterministic processes strongly influenced the distribution, while stochastic processes were not at play. Environmental drivers for generalists and specialists differed, as did their importance. Elevation, total nitrogen and pH were the main factors determining habitat generalists, and soil water content, nitrate nitrogen and pH had the strongest impacts on specialists. Moreover, variation partitioning analysis revealed that environmental selection had a much greater impact on both generalists (17.7% of pure variance was explained) and specialists (3.6%) than spatial factors. However, generalists had a much stronger response to spatial factors (2.3%) than specialists (0.3%). More importantly, null models of β-diversity suggested that specialists deviated significantly from non-neutral assembly mechanisms (relative null deviation= 0.64-0.74) relative to generalists (0.16-0.65) (< 0.05). These results indicate that generalists and specialists are governed by different assembly mechanisms and present distinct biogeographical patterns. The large proportion of unexplained variation in specialists (93.3%) implies that very complex assembly mechanisms exist in the assembly of specialists across elevational gradients on the subalpine slope of Mount Wutai. It is essential to understand the microbial community assembly at a more refined level, and to expand the current understanding of microbial ecological mechanisms.
Resource status and seasonal variation of plankton in the Xaitongmoin Reach of the Yarlung Zangbo River
雅鲁藏布江谢通门江段浮游生物资源现状及其季节动态
The distance decay of similarity in biogeography and ecology
DOI:10.1046/j.1365-2699.1999.00305.x URL [本文引用: 1]
A general framework for quantitatively assessing ecological stochasticity
Distribution of algae and cyanobacteria of biological soil crusts along the elevation gradient in mountain plant communities at the Northern Urals (Russian European Northeast)
DOI:10.1007/s11629-021-6952-7 [本文引用: 1]
Phytoplankton in the Mitika Wetland, Tibet, China. 1. Spatio-temporal niche of dominant species
DOI:10.18307/2021.0616 URL [本文引用: 2]
西藏麦地卡湿地的浮游植物. 1. 优势种的时空生态位
Variations of phytoplankton biodiversity in different streams of Niyang River
尼洋河不同河段浮游植物群落多样性差异研究
Quantifying the roles of immigration and chance in shaping prokaryote community structure
Naturally occurring populations of bacteria and archaea are vital to life on the earth and are of enormous practical significance in medicine, engineering and agriculture. However, the rules governing the formation of such communities are still poorly understood, and there is a need for a usable mathematical description of this process. Typically, microbial community structure is thought to be shaped mainly by deterministic factors such as competition and niche differentiation. Here we show, for a wide range of prokaryotic communities, that the relative abundance and frequency with which different taxa are observed in samples can be explained by a neutral community model (NCM). The NCM, which is a stochastic, birth-death immigration process, does not explicitly represent the deterministic factors and therefore cannot be a complete or literal description of community assembly. However, its success suggests that chance and immigration are important forces in shaping the patterns seen in prokaryotic communities.
Latitudinal distribution of zooplankton communities in the Western Pacific along 160° E during summer 2014
DOI:10.1016/j.jmarsys.2017.01.011 URL [本文引用: 1]
Using diatom assemblages to assess urban stream conditions
DOI:10.1007/s10750-005-1613-3 URL [本文引用: 1]
Molecular biogeography of planktonic and benthic diatoms in the Yangtze River
DOI:10.1186/s40168-019-0771-x
PMID:31806016
[本文引用: 1]
Diatoms are of great significance to primary productivity in oceans, yet little is known about their biogeographic distribution in oligotrophic rivers.With the help of metabarcoding analysis of 279 samples from the Yangtze River, we provided the first integral biogeographic pattern of planktonic and benthic diatoms over a 6030 km continuum along the world's third largest river. Our study revealed spatial dissimilarity of diatoms under varying landforms, including plateau, mountain, foothill, basin, foothill-mountain, and plain regions, from the river source to the estuary. Environmental drivers of diatom communities were interpreted in terms of photosynthetically active radiation, temperature, channel slope and nutrients, and human interference. Typical benthic diatoms, such as Pinnularia, Paralia, and Aulacoseira, experienced considerable reduction in relative abundance downstream of the Three Gorges Dam and the Xiluodu Dam, two of the world's largest dams.Our study revealed that benthic diatoms are of particular significance in characterizing motile guild in riverine environments, which provides insights into diatom biogeography and biogeochemical cycles in large river ecosystems.
Vertical distribution characteristics and influencing factors of phytoplankton community structure in Qiandao Lake
千岛湖浮游植物群落结构的垂向分布特征及其影响因素
Community assembly of bacteria and archaea in coastal waters governed by contrasting mechanisms: A seasonal perspective
DOI:10.1111/mec.v29.19 URL [本文引用: 1]
Analysis on characteristics and variation trend of annual runoff of mainstream of Yarlung Tsangpo River
雅鲁藏布江干流年径流变化趋势及特性分析
Spring phytoplankton community structure and niche analysis of dominant species in Chishui River
赤水河春季浮游植物群落结构变化及其优势种生态位分析
Effects of anthropogenic intensity on bacterioplankton community structure in Jinjiang River
人类活动强度对锦江浮游细菌群落结构的影响
Spatial and temporal distribution patterns and driving mechanisms of ciliate communities in the midstream and downstream reaches of the Lhasa River
DOI:10.17520/biods.2022012
[本文引用: 3]
<p id="p00010"><strong>Aims:</strong> As a high-altitude water area, the Lhasa River’s aquatic ecosystem has a high research value due to its special environmental conditions. In recent years, studies on the high-altitude water area have gradually increased, but there are few studies on the community structure of ciliates in the Lhasa River. We conducted this study to explore the composition pattern, spatial and temporal diversity pattern, and maintenance mechanism of ciliate communities in the midstream and downstream reaches of the Lhasa River. <br> <strong>Methods:</strong> Seventeen samples were collected from the middle and lower reaches of the Lhasa River in May 2015 and August 2015, and October 2016. In-vivo observation, Rugo’s iodine solution fixation staining, and Wilbert’s protein silver method were utilized for species identification. The spatial and temporal differences of community structure were analyzed by the Shannon diversity index, Margalef index, and richness. The interactions between ciliate groups were analyzed through co-occurrence network. The effects of physical and chemical factors on ciliate community structures were investigated using redundancy analysis (RDA). <br> <strong>Results:</strong> There was no significant difference in the Shannon index between seasons and river segments. The richness and Margalef index were significantly different among the reaches. The correlation between nodes in the midstream and downstream of the co-occurrence network is primarily positive. Dissolved oxygen (DO), total nitrogen (TN), total phosphorus (TP), and total dissolved salt (TDS) are the key factors affecting ciliate community structures. <br> <strong>Conclusion:</strong> The ciliate community structures in the midstream and downstream of the Lhasa River exhibited no significant seasonal differences but significant spatial differences. At the class level, the interaction between ciliates was dominated by synergy, and there were complex interactions among different groups. On the whole, the interaction between ciliates was more complex in spring and simpler in summer. The community structures of ciliates in the midstream and downstream of the Lhasa River was influenced by several environmental factors.</p>
拉萨河中下游纤毛虫群落时空分布模式及其驱动机制
DOI:10.17520/biods.2022012
[本文引用: 3]
为了探究拉萨河中下游纤毛虫群落的组成模式、时空多样性格局及其维持机制, 本文于2015年5月和8月以及2016年10月在拉萨河中下游17个样点进行采样, 采用活体观察、鲁哥氏碘液固定染色以及Wilbert蛋白银法相结合的物种鉴定方法, 对纤毛虫群落结构进行了研究。通过Shannon多样性指数、Margalef丰富度指数、物种数分析群落结构时空上的差异性; 通过共现网络分析纤毛虫类群之间的相互作用; 通过冗余分析(redundancy analysis, RDA)探讨水体理化因子对纤毛虫群落结构的影响。结果表明, Shannon多样性指数在季节和河段间没有显著性差异; Margalef丰富度指数、物种数在河段间存在极显著性差异; 中游和下游河段共现网络节点间的相关关系均以正相关为主; 溶解氧(DO)、总氮(TN)、总磷(TP)、总溶解盐(TDS)是影响纤毛虫群落结构的关键因子。综上所述, 拉萨河中下游纤毛虫群落结构在季节间没有显著差异, 在空间上具有显著差异; 纤毛虫在纲级水平上类群间的相互作用以协同作用为主导, 不同类群间存在复杂的相互作用, 整体上互作关系在春季较为复杂、夏季较为简单; 影响拉萨河中下游纤毛虫群落结构是多个环境因子共同作用的结果。
Biogeography of spring phytoplankton community in the coastal waters of northern Zhejiang
春季浙北海域浮游植物群落的空间分布
Community structure variations and driving factors of eukaryotes phytoplankton in Danjiangkou Reservoir in summer and winter
丹江口水库夏冬季真核浮游植物群落结构变化及其驱动因素
Similar geographic patterns but distinct assembly processes of abundant and rare bacterioplankton communities in river networks of the Taihu Basin
DOI:10.1016/j.watres.2022.118057 URL [本文引用: 1]
Effects of different hypersalinity models on the photo-physiological performances and related gene expression in Ulva prolifera
不同模式高盐胁迫对浒苔光合生理及相关基因表达的影响
DOI:10.3969/j.issn.1001-909X.2019.02.008
[本文引用: 1]
为探讨高盐及盐度变化对浒苔光合生理的影响以及浒苔在面临高盐胁迫时表现出的耐盐性,本文选取浒苔(Ulva prolifera)为供试材料,设置3个盐度变化处理组:对照组(CK)始终保持盐度25;处理组1(T1)经过盐度30适应3 d后增加到盐度35;处理组2(T2)长期处于盐度35,研究高盐及盐度变化对浒苔生长、光合色素含量、暗呼吸速率和光合放氧速率以及核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)和钙调蛋白(CaM)的基因表达量水平的影响。结果表明:与对照组相比,高盐会抑制浒苔的相对生长速率和光合生理,T1、T2处理组均显著抑制浒苔的生长以及净光合作用速率,且T2处理组的抑制作用更强。高盐处理对浒苔光合色素的含量及其比值、暗呼吸速率的影响不显著,但随着藻体的成熟,浒苔光合色素的含量显著降低,并且暗呼吸速率显著增加。高盐也同时影响了rbcL和cam的基因表达水平,比较0、3和6 d三个取样点结果,T1盐度递增组的基因表达量高于T2长期高盐组,盐度逐步提高有利于增加浒苔对高盐度的适应能力。这一结果有助于解释浒苔在形成绿潮草垫以及退潮干出期间对盐度提高的适应。
Stochastic community assembly: Does it matter in microbial ecologyv
