Phytoplankton response to the summer 2015 heat wave - a case study from prealpine Lake Mondsee, Austria
Phytoplankton response to the summer 2015 heat wave - a case study from prealpine Lake Mondsee, Austria
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DOI：
10.1080/20442041.2017.1294352
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发表时间：
2017-01-01
期刊：
影响因子：
3.1
通讯作者：
Weisse, Thomas
中科院分区：
文献类型：
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作者：
Bergkemper, Victoria;Weisse, Thomas
奥地利蒙得西前高山湖深处的浮游植物对热浪的反应总体上是次要的，尽管温度对湖最深处的浮游植物群落有显著影响。我们没有检测到营养物质的显著影响。利用光学显微镜(Utermohl技术)、FlowCAM和声学流式细胞术(AFC)3种互补光学方法，我们发现湖底浮游植物的水平变化相对较小，而浮游植物群落组成在湖中心站0-20m水层的整合发生了显著变化。这些变化主要是由于热浪期间冬凌草的峰值从11m垂直移动到16m造成的。从6月底到7月初，该地区连续6天测量到气温达到或超过30摄氏度，这是2015年夏季记录的3次热浪中的第一次；近岸表层水温超过27摄氏度。在热浪期间，我们在蒙得西湖的9个站进行了4次采样，分析了温度、营养水平、电导率、pH和浮游植物群落。除了报道水温升高对深层层状湖泊中藻类组合的影响外，我们还讨论了不同光学方法识别和计数浮游植物的利弊。对于未来类似于本研究的实地活动，我们建议使用光学显微镜来评估大型或稀有物种，如Ceratium hirundinella，以及AFC、FlowCAM或类似的半自动设备，用于丰富的中小型物种。
Phytoplankton response to a heat wave in deep prealpine Lake Mondsee, Austria, was minor overall, although temperature significantly affected the epilimnetic phytoplankton assemblage at the deepest site of the lake. We detected no significant effect of nutrients. Using 3 complementary optical methods-light microscopy (Utermohl technique), FlowCAM, and acoustic flow cytometry (AFC)-we found relatively low horizontal variation in the epilimnion but significant changes in phytoplankton community composition integrated over the 0-20 m water layer at the central station of the lake. These changes were mainly caused by a vertical shift in the Planktothrix rubescens peak from 11 to 16 m during the heat wave. Air temperatures reaching or exceeding 30 degrees C were measured in the area during 6 consecutive days at the end of June to the beginning of July, the first of 3 heat waves recorded during summer 2015; in-shore surface water temperature exceeded 27 degrees C. We sampled 9 stations across Lake Mondsee on 4 occasions during the heat wave and analysed temperature, nutrient levels, conductivity, pH, and the phytoplankton community. In addition to reporting the implications of increasing water temperatures for the algal assemblage in a deep stratified lake, we discuss the pros and cons of the different optical methods for phytoplankton identification and counting. For future field campaigns similar to the present study, we recommend using light microscopy to assess large or rare species, such as Ceratium hirundinella, and AFC, FlowCAM, or similar semi-automated devices for abundant small-to medium-sized species.