A whole‐lake experiment confirms a small centric diatom species as an indicator of changing lake thermal structure
A whole‐lake experiment confirms a small centric diatom species as an indicator of changing lake thermal structure
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全湖实验证实了一种小的中心硅藻物种是改变湖泊热结构的指标
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发表时间：
2016
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通讯作者：
N. Anderson
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作者：
J. Saros;R. Northington;Dennis S. Anderson;N. Anderson
在北半球的许多湖泊中，古矿物学记录显示，在过去的一个世纪里，小型中心硅藻--星状双胞藻的相对丰度发生了变化，这种广泛的变化被归因于气候变化。具体地说，小规模实验和目前的空间分布模式表明，当湖泊混合深度较浅时，这种物种更多，但缺乏在整个湖泊尺度上对这一假设的直接测试。我们在一个偏远的北极湖泊进行了全湖混合操作，夏季通常有相对较浅的热层化和大量的狼毒种群。我们采用了“事前-事后-控制-影响”的设计，使用了一个实验湖和一个控制湖。2013年夏天，在没有对两个湖泊进行控制的情况下，对两个湖泊的湖热结构和硅藻种群进行了监测，并在2014年夏天再次对实验湖泊进行了监测，当时实验湖泊被操纵，以实现更深的混合深度。在2014年的深层混合操作期间，狼毒的丰度下降，而在对照湖中，在同一时间段内，星藻的丰度增加。在两个湖泊中发现的其他四种硅藻分类群在两年中都没有观察到相同的模式。我们的结果证实了使用星形藻作为改变湖泊热结构的指标，并表明这一工具在湖泊沉积物记录中的广泛应用将更好地洞察湖泊生态系统对气候的响应的长期变异性。
In many lakes across the Northern Hemisphere, paleolimnological records have revealed that the relative abundances of the small centric diatom, Discostella stelligera, changed over the past century, with these widespread shifts attributed to climate change. Specifically, small‐scale experiments and current spatial distribution patterns suggested that this species is more abundant when lake mixing depths are shallower, but a direct test of this hypothesis at the whole‐lake scale was lacking. We conducted a whole‐lake mixing manipulation in a remote arctic lake that normally has relatively shallow thermal stratification and abundant D. stelligera populations during the summer. We employed a “Before‐After‐Control‐Impact” design using an experimental lake and a control lake. Lake thermal structure and diatom populations were monitored in both lakes in summer 2013 without manipulating either lake, and again in summer 2014 when the experimental lake was manipulated to achieve deeper mixing depths. The abundance of D. stelligera declined during the manipulated period of deeper mixing in 2014, while it increased during the same time frame in the control lake. The same pattern was not observed for the four other diatom taxa found in both lakes in both years. Our results confirm the use of D. stelligera as an indicator of changing lake thermal structure, and suggest that the broader application of this tool to lake sediment records will yield greater insight into longer‐term variability in the response of lake ecosystems to climate.