Spatial and Temporal Variability in the Ecosystem Metabolism of a High-elevation Lake: Integrating Benthic and Pelagic Habitats
Spatial and Temporal Variability in the Ecosystem Metabolism of a High-elevation Lake: Integrating Benthic and Pelagic Habitats
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DOI：
10.1007/s10021-011-9471-5
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发表时间：
2011-11-01
期刊：
影响因子：
3.7
通讯作者：
MacIntyre, Sally
中科院分区：
文献类型：
--
作者：
Sadro, Steven;Melack, John M.;MacIntyre, Sally
我们的特点是空间和时间的变化，净生态系统生产力（NEP），社区呼吸（CR），和总初级生产力（GPP）在无冰的季节，在贫营养高海拔湖泊使用高频率测量溶解氧。我们结合使用的自由水和孵化室的测量比较浮游和底栖栖息地，并估计其相对贡献全湖代谢。尽管短暂的优势异养融雪后，无论是自由水和孵化室的测量证实了在整个无冰季节的所有栖息地的表层自养。与此相反，底栖生物孵化室显示，底栖生物是一贯的异养。虽然温度是最强的季节性驱动器的底栖代谢，浮游细菌密度和有机质质量指数解释了最多变的中上层代谢。在底栖生物代谢的驱动下，沿岸的自由水GPP和CR的测量值是远洋生境的两倍。然而，覆盖在沿岸的底栖生物的水柱初级生产率足够高，以克服净底栖异养，和季节平均NEP在沿岸的栖息地仍然是积极的，并没有显着不同的远洋栖息地。底栖动物的代谢率平均约占整个湖泊代谢的25%。中上层代谢测量受沿岸的率约一半的时间，与平流和水柱稳定性的函数之间的隔离程度。这些结果强调了在物理动力学背景下表征代谢的空间和时间变异的重要性，并对贫营养湖泊中底栖代谢必然大于浮游代谢的概念提出了挑战。
We characterized spatial and temporal variability in net ecosystem production (NEP), community respiration (CR), and gross primary production (GPP) over an ice-free season in an oligotrophic high-elevation lake using high-frequency measurements of dissolved oxygen. We combined the use of free-water and incubation chamber measurements to compare pelagic and benthic habitats and estimate their relative contributions to whole-lake metabolism. Despite a brief period of predominant heterotrophy after snowmelt, both free-water and incubation chamber measurements confirmed autotrophy of the epilimnion in all habitats throughout the ice-free season. In contrast, benthic incubation chambers showed the benthos to be consistently heterotrophic. Although temperature was the strongest seasonal driver of benthic metabolism, bacterioplankton density and indexes of organic matter quality explained the most variability in pelagic metabolism. Driven largely by benthic metabolism, free-water measurements of GPP and CR were twice as high in littoral than pelagic habitats. However, rates of water column primary production overlying the littoral benthos were high enough to overcome net benthic heterotrophy, and seasonal mean NEP in littoral habitats remained positive and not significantly different from pelagic habitats. Benthic rates averaged about 25% of whole lake metabolism. Pelagic metabolism measurements were affected by littoral rates about half the time, with the degree of isolation between the two a function of advection and water column stability. These results emphasize the importance of characterizing spatial and temporal variability in metabolism within the context of physical dynamics and challenge the notion that benthic metabolism will necessarily be larger than pelagic metabolism in oligotrophic lakes.