Comparing effects of oligotrophication and upstream hydropower dams on plankton and productivity in perialpine lakes
Comparing effects of oligotrophication and upstream hydropower dams on plankton and productivity in perialpine lakes
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DOI：
10.1029/2007wr005868
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发表时间：
2007-12
影响因子：
5.4
通讯作者：
D. Finger;M. Schmid;A. Wüest
中科院分区：
文献类型：
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作者：
D. Finger;M. Schmid;A. Wüest
近几十年来，由于高效的污水处理和上游水电运行改变了水的浑浊度，许多高山周边湖泊受到了少营养化的影响。这种同时发生的环境变化常常引起公众对观察到的生产率下降的实际原因的辩论。我们以布里恩茨湖（瑞士）为例，通过建模和数据解释相结合的方法来评估这两种变化的影响。布里恩茨湖是一个典型的贫营养近高山湖泊，位于几个水电站水库的下游。在不同养分负荷和不同颗粒输入动力学条件下，建立了物理k - i格式和生物地球化学平流-扩散-反应模型。模拟结果与1999年至2004年收集的长期生物数据进行了比较。分析表明，营养供应的增加增加了藻类的营养价值，刺激了浮游动物的生长，而浮游植物的生长受到自上而下的控制。年综合生产力仅受浑浊度变化的轻微影响，因为磷限制普遍存在。模拟结果表明，上游水电运行导致冬季浊度增加，导致春季生产高峰延迟。因此，整个营养循环被季节性地推迟，给下游湖泊的浮游动物和鱼类造成了额外的压力。
In recent decades, many perialpine lakes have been affected by oligotrophication due to efficient sewage treatment and by altered water turbidity due to upstream hydropower operations. Such simultaneous environmental changes often lead to public debate on the actual causes of observed productivity reductions. We evaluate the effects of those two changes by a combined approach of modeling and data interpretation for a case study on Lake Brienz (Switzerland), a typical oligotrophic perialpine lake, located downstream of several hydropower reservoirs. A physical k‐ɛ scheme and a biogeochemical advection‐diffusion‐reaction model were implemented and applied for several hypothetical scenarios with different nutrient loads and different particle input dynamics. The simulation results are compared to long‐term biotic data collected from 1999 to 2004. The analysis shows that enhanced nutrient supply increases the nutritious value of algae, stimulating zooplankton growth, while phytoplankton growth is limited by stronger top‐down control. Annually integrated productivity is only slightly influenced by altered turbidity, as phosphorous limitation prevails. Simulations indicate that the spring production peak is delayed because of increased turbidity in winter caused by upstream hydropower operation. As a consequence, the entire nutrient cycle is seasonally delayed, creating an additional stress for zooplankton and fish in the downstream lake.