Interannual fluctuations in primary production: Direct physical effects and the trohic cascade at Castle Lake, California
Interannual fluctuations in primary production: Direct physical effects and the trohic cascade at Castle Lake, California
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初级生产的年际波动：加利福尼亚州城堡湖的直接物理效应和灾难性级联
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
C. Goldman
中科院分区：
文献类型：
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作者：
A. Jassby;T. Powell;C. Goldman
直接的物理效应和级联的营养相互作用共同决定了加利福尼亚州卡斯尔湖初级生产力的季节模式的年际变化。用主成分分析方法研究了L-L 986夏季生产力的深度-时间分布。发现了两种特征模式，共同解释了年际变化的60%-70%。第一种模式对应于在6月和7月的低潮期形成的深生产力极大值。第一种模式的变异性是由于春季冰层破裂和水力冲刷时间的年复一年变化对浮游植物种群的直接影响。在厄尔尼诺-南方涛动现象期间，与长期平均相比，第一种模式是异常强或弱的。第二个特征模式对应于8月和9月出现的混合层生产力最大值。第二种模式的变异性来自较高水平的营养相互作用：虹鲑鱼以夏末的玫瑰色水蚤种群为食，而后者又以混合层藻类群落为食。此外，虹鱼种群数量的一些变化是由于来自人类的垂钓压力年复一年的差异造成的。这些结果表明，生态系统属性(初级生产力)的年际变异性如何通过食物网的顶部和底部同时作用的力来控制。
Direct physical effects and cascading trophic interactions operate together to determine interannual variability in the seasonal pattern .of primary productivity at Castle Lake, California. Principal component analysis was used to investigate the depth-time distributions of productivity for summers 196 l-l 986. Two characteristic patterns were found, together accounting for 60-70% of the year-to-year variability. The first pattern corresponds to the deep productivity maximum that forms in the hypolimnion in June and July. Variability in this first pattern arises from the direct effects on phytoplankton populations of year-to-year changes in timing of ice breakup and hydraulic flushing in spring. The first pattern is unusually strong or weak, compared to the longterm average, during the phenomenon of El Niiio-Southern Oscillation. A second characteristic pattern corresponds to the mixed-layer productivity maximum that develops in August and September. Variability in this second pattern arises from trophic interactions at higher levels: rainbow trout feed on late-summer Daphnia rosea populations, which in turn graze on the mixed-layer algal community. In addition, some of the variability in the rainbow trout population arises from yearto-year differences in angling pressure from humans. These results demonstrate how interannual variability in an ecosystem property (primary productivity) can be controlled by forces acting simultaneously through the top and the base of the food web.