Probing whole‐stream metabolism: influence of spatial heterogeneity on rate estimates
Probing whole‐stream metabolism: influence of spatial heterogeneity on rate estimates
复制标题
探索全流代谢：空间异质性对速率估计的影响
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
W. Dodds
中科院分区：
文献类型：
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作者：
Adam C. Siders;D. Larson;Janine Rüegg;W. Dodds
摘要
自50多年前引入该方法以来，一直通过测量流中氧气(O2)浓度来估计全流新陈代谢。然而，测量位置和估计方法对代谢率的影响还没有得到充分的研究。我们研究了氧气探测器的放置位置(即深度，与水深的分离)，方法的差异(1站，2站，面积加权)和覆盖长度如何影响Tallgras草原分水岭全流新陈代谢的估计速度。
由于水流中断，在深水区所作的新陈代谢估计与在死水中所作的估计不同，而由于热分层(暂时性流动中断)，在深水池中所作的估计与地面估计不同。单站呼吸估计值不同于较短的两站范围范围估计值(约2000万米)，但更类似于较大的两站范围范围估计值(约100百万米)。相反，1站总初级生产力最类似于上游立即发生的短2站河段，而较长的2站河段长度变得不那么相似。考虑最长距离尺度的不同估算方法(1站、2站、面积加权)不会导致不同的代谢率。
暖天期间水池温度分层的暂时现象使水池底部与地表水分离，这可能不仅影响水池估计，也影响下游水池的估计(即白天水池底部呼吸产生的氧气赤字在混合过程中突然向下游移动)。
由于小尺度异质性对群落呼吸的影响，氧探头的放置位置很重要，并根据生境类型和到达长度(即规模)来影响速率估计。范围长度的选择对于研究来说可能是关键的，这取决于局部异质性是重要的还是应该平均。
我们的结论是，直观地使用至少是溪流宽度10倍的水平线和河段可能适合于全流新陈代谢估计，尽管在放置探头时需要仔细考虑所需的准确河段长度和潜在的溪流特定特征，如分层水池。我们鼓励其他研究报告氧气探测器在溪流中的放置特征，并考虑当地栖息地异质性的潜在混杂因素。
Summary
Whole-stream metabolism has been estimated by measuring in-stream oxygen (O2) concentrations since the method was introduced over 50 years ago. However, the influence of measurement location and estimation method on metabolism rates is understudied. We examined how the placement of O2 probes (i.e. depth, separation from the thalweg), differences in methodology (1-station, 2-station, area-weighted) and reach lengths influenced estimated rates of whole-stream metabolism in a tallgrass prairie watershed.
Metabolism estimates made in the thalweg differed from estimates made in backwaters due to disconnection in flow, and estimates made in deep pools differed from surface estimates due to thermal stratification (temporary flow disconnection). The 1-station respiration estimates differed from short 2-station reach-scale estimates (c. 20 m) but were more similar to larger 2-station reach-scale estimates (c. 100 m). In contrast, the 1-station gross primary production was most similar to the short 2-station reaches occurring immediately upstream and became less similar at longer 2-station reach lengths. The different estimation methodologies (1-station, 2-station, area-weighted) accounting for the longest reach scale did not result in different metabolism rates.
The temporary phenomena of thermal stratification of stream pools during a warm day, which disconnected pool bottoms from the surface waters, likely affected not only the pool estimates but also estimates made in the downstream thalweg (i.e. an O2 deficit accrued from respiration during the day in the bottom of the pool abruptly moved downstream during mixing).
Oxygen probe placement mattered and affected rate estimates according to habitat type and reach length (i.e. scale) due to the influence of small-scale heterogeneity on community respiration. Selection of reach length can be critical for studies depending on whether local heterogeneity is of interest or should be averaged.
We conclude that the intuitive use of thalwegs and reaches that are at least 10 times the stream width are likely appropriate for whole-stream metabolism estimates, although the exact reach length necessary and potential stream-specific characteristics, such as stratified pools, need to be carefully considered in probe placement. We encourage other studies to report the placement characteristics of O2 probes in streams as well as consider the potential confounding factor of local habitat heterogeneity.
影响因子：
2.7
作者：
Demars, Benoit O. L.;Thompson, Joshua;Manson, J. Russell
通讯作者：
Manson, J. Russell