Spatial differences in dissolved silicon utilization in Lake Baikal, Siberia: Examining the impact of high diatom biomass events and eutrophication
Spatial differences in dissolved silicon utilization in Lake Baikal, Siberia: Examining the impact of high diatom biomass events and eutrophication
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DOI：
10.1002/lno.10792
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发表时间：
2018-07
影响因子：
4.5
通讯作者：
V. Panizzo;S. Roberts;G. Swann;S. McGowan;A. Mackay;E. Vologina;V. Pashley;M. Horstwood
中科院分区：
文献类型：
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作者：
V. Panizzo;S. Roberts;G. Swann;S. McGowan;A. Mackay;E. Vologina;V. Pashley;M. Horstwood
最近的研究强调了西伯利亚贝加尔湖如何应对气候变化（例如冰盖持续时间）、营养负荷和污染的直接和间接影响，表现为浮游植物/浮游动物种群、群落结构和季节演替的变化。在这里，我们结合并比较了叶绿素 a（藻类总生物量的估计）、类胡萝卜素色素（藻类生物标记）和湖水硅同位素地球化学 (δ30SiDSi) 的分析，以区分贝加尔湖溶解硅 (DSi) 吸收的空间模式。 2013 年 8 月，沿 0-180 m 的深度梯度对贝加尔湖三个流域（南、中、北）总共 15 个地点进行了采样。在透光区 DSi 浓度和 δ30SiDSi 成分的垂直剖面之间发现了强而显着的相关性（r = -0.81，p < 0.001），尽管这些在中央盆地无光区最强（r = -0.98，p < 0.001）。数据反驳了微微蓝细菌吸收 DSi 的假设。藻类生物量分布和高表面 δ30SiDSi 成分表明南部盆地生产力更高，而北部盆地更贫营养。 δ30SiDSi 特征在中央盆地地点的深度（20 m）处最高，表明深部叶绿素最大值处的 DSi 利用率更高（10-40%）。 DSi 限制发生在中上层盆地，可能反映了硅藻生物量高的水华事件（Aulacoseira baicalensis）。与此同时，在受水文限制较多的马洛莫尔浅海地区（中央盆地），δ30SiDSi 成分和微微蓝细菌（玉米黄质）浓度较高，分别表明“Aulacoseira 开花年”和夏季持续养分供应的遗留问题（例如，局部富营养化）。
Recent research has highlighted how Lake Baikal, Siberia, has responded to the direct and indirect effects of climate change (e.g., ice‐cover duration), nutrient loading, and pollution, manifesting as changes in phytoplankton/zooplankton populations, community structure, and seasonal succession. Here, we combine and compare analyses of chlorophyll a (an estimate of total algal biomass), carotenoid pigments (biomarkers of algal groups), and lake water silicon isotope geochemistry (δ30SiDSi) to differentiate spatial patterns in dissolved silicon (DSi) uptake at Lake Baikal. A total of 15 sites across the three basins (south, central, and north) of Lake Baikal were sampled in August 2013 along a depth gradient of 0–180 m. Strong, significant correlations were found between vertical profiles of photic zone DSi concentrations and δ30SiDSi compositions (r = −0.81, p < 0.001), although these are strongest in the central basin aphotic zone (r = −0.98, p < 0.001). Data refute the hypothesis of DSi uptake by picocyanobacteria. Algal biomass profiles and high surface δ30SiDSi compositions suggest greater productivity in the south basin and more oligotrophic conditions in the north basin. δ30SiDSi signatures are highest at depth (20 m) in central basin sites, indicating greater (10–40%) DSi utilization at deep chlorophyll maxima. DSi limitation occurs in the pelagic central basin, probably reflecting a high diatom biomass bloom event (Aulacoseira baicalensis). Meanwhile in the more hydrologically restricted, shallow Maloe More region (central basin), both high δ30SiDSi compositions and picocyanobacteria (zeaxanthin) concentrations, respectively point to the legacy of an “Aulacoseira bloom year” and continuous nutrient supply in summer months (e.g., localized eutrophication).